Tekton Double Impacts
In case anyone is curious, Mr. Alexander's patent that is cited in the DI description can be found here. Although after reading its 14 pages I'd have to say that it doesn't provide a great deal more information than what is stated at the Tekton website. Also, for those who may consider how much amplifier power is desirable for use with this speaker, it should be kept in mind that given its 4 ohm nominal impedance the stated sensitivity of 98.82 db/2.83 volts/1 meter is equivalent to 95.82 db/1 watt/1 meter. That follows from the fact that while 2.83 volts into 8 ohms corresponds to 1 watt, 2.83 volts into 4 ohms corresponds to 2 watts. That distinction is particularly relevant in the case of tube amps, which in most cases cannot supply more power into 4 ohms than into 8 ohms. Corelli, best of luck with your purchase. Regards, -- Al |
Specifying speaker sensitivity based on 2.83 volts rather than 1 watt seems to be pretty much the norm these days, among manufacturers and also among reviewers who provide measurements (e.g., John Atkinson in Stereophile, and measurements performed by the National Research Council of Canada that I’ve seen published in conjunction with reviews at SoundStage.com). I wouldn’t consider that to be deceptive, it’s just something to be aware of, especially if tube amps are to be used. Per my earlier comment, basing the spec on 2.83 volts vs. 1 watt makes no difference in the case of an 8 ohm speaker, assuming the 8 ohm spec is realistic, while resulting in a 3 db difference for a 4 ohm speaker. Part of the rationale for using 2.83 volts is presumably the fact that many high quality solid state amps can supply twice as much power into 4 ohms as into 8 ohms, which would compensate for that 3 db. A separate issue, of course, is the accuracy of any such specs. Regarding the Enzo XL, its spec per the website is 96.5 db/1 watt/1 meter, while Stereophile measured 90.6db/2.83 volts/1 meter, with the speaker being accurately rated at 8 ohms. I’ve seen such disparities for quite a few speakers in the past, typically in the area of 2 to 6 db. In some cases the disparity is perhaps accounted for or contributed to by an unstated assumption on the part of the manufacturer of some amount of "room gain." In some cases another contributing factor may be that the manufacturer bases the spec on the speaker’s sensitivity at a specific frequency, which may be somewhat greater than its sensitivity as averaged over a broad range of frequencies (which is what JA and the NRC do). That kind of "specmanship" I **would** consider to be a bit deceptive, in contrast to the 2.83 volt/1 watt issue. Regards, -- Al |
Mac48025 3-6-2017Yes, generally speaking. Although if the impedance stays relatively high at most or all frequencies lack of flatness will be less significant than if it dips down to low values at some frequencies. For example the impedance curve of the Enzo XL that I linked to earlier varies a lot over the frequency range, but never goes much below 6 ohms, which minimizes the significance of that variation. Also, the phase angle of the impedance can be a significant factor in many cases. That is shown as a dotted line in the impedance plots in Stereophile’s measurements, and corresponds to the markings on the axis at the right side of the graph. Very negative phase angles that may occur at various frequencies, especially if they occur at frequencies for which the magnitude of the impedance (the number of ohms) is low, will work in the direction of making the speaker a more challenging load for the amplifier. JA will usually comment on that. For example, in the Enzo XL review he commented that "the Tekton speaker’s impedance magnitude (fig.1, solid trace) remains above 6 ohms at all frequencies, and the electrical phase angle (dotted trace) reaches extreme values only when the magnitude is high. The Enzo XL is therefore well suited for use with low-powered tube amplifiers." The "extreme values" he refers to for the phase angle are in the vicinity of -45 degrees, but occur at frequencies at which the impedance magnitude is around 10 ohms or more. Regards, -- Al |
IMO Ozzy’s concern about how the DI’s impedance may vary over the frequency range is well founded, especially given the practical issues he mentioned that would be involved in auditioning and possibly having to return the speakers. The 4.1 ohm output impedance of his Atma-Sphere M60s is, as far as I can recall, more than twice as high as the output impedance of any other amplifier that has been reported in this thread as having been used with a DI. (For example the LTA MZ2 has a specified output impedance of 2 ohms, and according to a TAS review the Frankenstein, at least in its MkII version, has an output impedance of 1.8 ohms). The Zero autoformers he has can certainly reduce any impedance-related issues he might have pairing the M60 with the DI, and the capabilities of his DEQX might also be able to help with any such issues, but to what degree and with what audible side-effects is obviously difficult or impossible to predict. Best regards, -- Al |
One more reason, Ozzy, is that you would most likely have to move the speakers away from and then back to the listening position in order to perform the DEQX calibrations. And quite possibly you would have to do that multiple times, to fully optimize the calibrations. Certainly doable, of course, but not a trivial task as it is with your much smaller DIY speakers. Best regards, -- Al |
Tom (Mac48025), my congratulations as well for this excellent improvement to an already very fine system. And kudos to Aric for making it possible. Regarding the hum/buzz issue, I don’t know how you have the components physically arranged, but if your MZ2 is in close proximity to the amp or to any of your other components, including its own external power supply, you might try repositioning it to increase the distance between it and everything else in the system. I particularly suggest that because in looking at photos of the MZ2’s innards it appears that its output signal grounds are directly connected to its chassis. Which I’m thinking might result in a small hum/buzz voltage being applied to the input ground of Aric’s amplifier corresponding to whatever small AC-related voltage may be magnetically induced onto the MZ2’s chassis by a nearby component. As you are probably aware, use of a cheater plug as a long term solution results in a small but non-zero safety risk. (Note Aric’s statement above that the cheater plug was suggested "as a test"). In any event, congratulations once again! Best regards, -- Al |
@david_ten @343mps The visible text of the link in 343's post will work, but what is hidden "underneath" the visible text, which is what the browser is directed to when the link is clicked, has two extraneous characters at the end, namely "> After clicking on the link, if those two characters are deleted from what appears in the address bar and "enter" is then hit, the intended image will appear. Regards, -- Al |
Hi Charles,
Your question is of course a logical and very valid one. After thinking about it a little, I believe I can explain how the 1 watt MicroZOTL amp can drive the DI to levels in the vicinity of 100 db at the listening position. Three things need to be considered: Output impedance, current capability, and power capability. I’ll mention first that the amp is rated, somewhat counter-intuitively for a tube amp, to be able to deliver more power into 4 ohms (1 watt) than into a higher impedance (0.5 watts into 14 ohms). And its output impedance is specified as a usefully low 2 ohms. How is that possible with a 6SN7, which like just about any small signal tube operates under relatively high voltage/low current/high impedance conditions? The key to the answer is that the ZOTL amps are not true OTLs in the traditional sense. As I know you’ll recall from discussions in other threads here, between the output tube and the output terminals of the amp is a transformer that operates at RF (not audio) frequencies, as well as some solid state switching devices. That circuit converts the high voltage/low current/high impedance condition under which the tube operates to a much lower voltage/higher current/lower impedance condition, while presumably being efficient enough to not sacrifice a significant amount of power in the process. (For a resistive load power = voltage x current, and when a transformer transforms voltage and current the product of the two cannot increase, since it is a passive device). So that takes care of output impedance and current capability. Regarding the 1 watt power capability of the amp: The speaker is rated to produce an SPL of 98.82 db at 1 meter for an input of 2.83 volts. Let’s call it 99 db. 2.83 volts into 4 ohms corresponds to 2 watts. So the 99 db becomes 96 db for a 1 watt input. Assuming that falls off with increasing distance at a rate of 6 db per doubling of distance, which is typical for non-planar speakers, at a typical listening distance of say 10 or 12 feet the 96 db would be reduced to about 86 db. If both of the speakers that are present are supplied with 1 watt, the overall acoustic power that is radiated into the room would increase by 3 db, relative to the output of a single speaker, but the increase would approach 6 db if the listener is approximately centered. That brings us to 92 db. “Room gain,” i.e., the effects of reflected energy in the room, would conceivably add something like 3 db or so. That brings us to 95 db. And probably another few db would be added as a result of some combination of dynamic headroom, conservatism in the 1 watt spec, and a small amount of clipping that would not be perceivable as such. Voila! Best regards, -- Al |
Treebeard1, regarding your question about output impedance, it was said earlier in the thread that the three pairs of outputs of the MZ2 (left and right preamp outputs, speaker outputs, and headphone outputs) are wired in parallel for each channel, and the same signal is provided to each of the three corresponding connectors. So the output impedance is 2 ohms regardless of whether the MZ2 is used as a preamp, as a 1 watt (into 4 ohms) power amp, or as a headphone amp. And it will have no problem driving your Halo A21. Regards, -- Al |
Mac48025 4-20-2017Thanks, Mac. And I believe I do know the answer. I believe the answer is that it is unpredictable :-) It will depend in part on how the impedances of each of the two versions of the speaker vary over the frequency range, in terms of both the magnitude of the impedance (i.e., the number of ohms), and the phase angle of the impedance (the degree to which the impedance has a capacitive or inductive component, as opposed to being purely resistive). And on how the amplifier reacts to those variations. It will also depend, of course, on whatever intrinsic sonic differences may exist between the two versions of the speaker. BTW, concerning bridging the LTA amps, I infer from various statements at their website that when the amps are used as monoblocks they are not being used in what is usually referred to as a bridged configuration. They are being used with the two channels connected in parallel. What is usually referred to as bridging generally provides much more than a 70% increase in power capability (potentially/theoretically as much as a 4x increase, although most designs fall short of realizing that much of an increase), but is often reported to compromise the sonics of an amplifier relative to the sonic quality the same amplifier provides in stereo mode. Especially if the amp is driving a low impedance speaker. So presumably/hopefully that sonic compromise would not occur with the LTA amps if they are "bridged," although the resulting increase in power capability is not all that great. (A 70% increase in power is about 2.3 db). Best regards, -- Al |
P.S. to my previous post: What I suspect is likely to make a more significant difference in sonics when the LTA amps are "bridged" than the resulting power increase, with the difference most likely being for the better, is the fact that the amp’s output impedance would be cut in half as a result of the channels being paralleled. And that potential benefit can be expected to be greater in degree in the case of the 4 ohm version of the DI than in the case of the 8 ohm version. Higher speaker impedance makes amplifier output impedance less critical, everything else being equal. Best regards, -- Al |
I'm looking for a good, dynamic, warm, speaker that has a real crisp tweeter and big inch woofers, and can play loud... Know of any ?Very few audiophile-oriented speakers can generate 110 to 112 db SPLs at 9.5 feet and be in their comfort zone, if they can do so at all. Especially speakers that are in the price range of the DI. Perhaps some Klipsch models would be suitable candidates, although I don't know if they would meet your other requirements. In any event, thanks for providing the thorough writeup. Regards, -- Al |
Given Nitrobob's preferred listening levels of 108 to 112 db, what would be surprising to me is if his impressions of the speaker did **not** differ considerably from most of the others that have been reported. Not only would I expect the sonic characteristics of the speaker to be significantly different at those levels than at the levels most of us listen at, due to the cabinet-related effects Bill mentioned as well as driver-related effects such as thermal compression and increased non-linearity, but I'd expect our hearing mechanisms to behave differently at those levels than at the levels most of us listen at. Regards, -- Al |
A few years ago one of our members who performs professionally in a classical symphony orchestra posted the following, in this thread. I would emphasize the words "continuous time weighted average" in his post. Recently, there was a post on the ICSOM board that I thought I would share the info from. ICSOM is the International Congress of Symphony and Opera Musicians, which consists of the musicians of the major US and some international orchestras.Regards, -- Al |
Craigl59 12-19-2017Absolutely! As I can attest having sat within 20 or 30 feet of the performer at more than a few classical concerts for solo piano. Which serves to illustrate why I and the poster I quoted both emphasized that the db levels cited in his post are based on a "continuous time weighted average." During many and often most of the milliseconds or even seconds between 95 db notes that may be produced with a piano the instantaneous SPL will be far lower than that. And consequently the "continuous time weighted average" will also be far lower. Best regards, -- Al |
Is the frequency a factor in the spl?I would think so, Stfoth, to some degree. That would seem likely based on the fact that (as you can see in the figure at the upper right of the Wikipedia page on "Equal Loudness Contour") our hearing mechanisms are most sensitive in the area of 3 to 4 kHz or so, while being considerably less sensitive at deep bass frequencies. So it wouldn’t surprise me if an organization such as OSHA has developed standards for maximum SPL exposure which take frequency into account, but if so I have no specific knowledge of them. Best regards, -- Al |
Another method of sending a PM is to click on the member's screen name in one of his or her posts, then click "Details," then "Marketplace Feedback," then "Send Message." BTW, the "Explore" tab David referred to appears on the main Audiogon home page, and on the Buy/Sell part of the site, but not on the Forum part of the site. Regards, -- Al |
Mofojo 5-25-2017If a second set of pre-outs is added the two sets would almost certainly be wired directly together inside the rear panel, as opposed to being driven by separate output stages. Consequently I would expect the results to be no different than using a good quality "hard y-adapter," such as this one from Audioquest, on the single set of outputs. In both cases (two sets of pre-outs or hard-y adapters) those results may or may not be good depending on the output impedance of the pre-outs, the input impedance of the sub, and the input impedance of the power amp. And also, if the output impedance of the pre-outs is high, on the lengths and capacitances of the two sets of cables that are involved. My belief is that the negative comments that are often seen about splitters are often and perhaps usually not due to the splitter itself, but are due to the inability of the component providing the signal to be able to drive the two sets of load impedances and the two sets of cables that are involved, with good results. The unbalanced input impedance of some of the JL subs is 50K, which would be encouraging, while it is only 10K for some other models, which could very possibly be a problem depending on the output impedance of the pre-outs and the input impedance of the particular power amp that would be used. I would suggest that you start by asking LTA what the output impedance of the pre-outs is, at 20 Hz as well as at the mid-range frequencies (such as 1 kHz) at which output impedances are usually specified. If the pre-outs are capacitively coupled the 20 Hz output impedance will probably be much higher than the output impedance at mid-range frequencies, and could result in roll-off of the deep bass content of the signals provided to both the sub and the main power amp. Regards, -- Al |
Willsw 5-26-2017Willsw, thanks, but those measurements (which I presume are from this review of the microZOTL2.0) pertain to the speaker-level outputs, not to the pre-out RCA connectors which were what was discussed in regard to splitting (or, alternatively, adding a second set of connectors). Specs and/or measurements of the output impedance of the pre-outs don’t seem to be available, but I would expect it to be MUCH higher than 2 ohms. Regards, -- Al |
Thanks, Willsw. I missed the statement in the review about the three outputs (RCA, speaker, headphone) being connected in parallel, which of course would not normally be done in a higher powered amp. So, yes, driving a sub and a separate power amp from the RCA jacks via a pair of splitters, or alternatively from a second pair of RCA jacks installed as an option, should work fine. Regards, -- Al |
Chris (Waltersalas), thanks very much for the thoroughness not only of your report, but especially for the thoroughness of the comparisons you have been performing between these two fine speakers. Your opinions always have extremely high credibility in my book, and in this case certainly help to validate the many very positive comments others have provided about the DIs. As well as adding an exclamation point (or three) to the remarkable value the DIs represent at their price point. As Mac said just above, "the good news is that no matter your choice you'll end up with an amazing pair of speakers." In my own case, given that the comparison seems to be a close one, with each speaker having mostly subtle pluses and minuses relative to the other, and given also that my listening room is my living room, appearance would be the overriding consideration (that being equally important to both me and my wife). (I chose the same quartersawn white oak option for my Ulysses as you did, btw). But again, the huge price differential between the two speakers further reinforces the remarkable achievement the DIs represent. Thanks again. Best regards, -- Al |
@milpai A concern I would have regarding the use of your high gain (29 db) and very powerful Parasound A21 with the DI is that you might find yourself having to set the volume control on your TVC very close to the bottom of its range, given the very high sensitivity of the DI. It appears that the TVC provides volume increments of 2 db, and a maximum attenuation of 54 db. **If** the published sensitivity specs for your Quad 21l speakers (88 db/2.83 volts/1 meter/6 ohms) are accurate, with the DI you would probably be using settings that are about 5 increments below the ones you use now. If those specs are optimistic, as is sometimes the case, figure on 6 or 7 increments below the settings you use now. Best regards, -- Al |
@milpai Sounds good re your volume control! As you realize, in contrast to many resistive-based controls a TVC will do well at low volume settings. The main concern, and I suspect the only concern, would be running out of range when you may want to listen at particularly low levels, and it sounds like that wouldn't happen with your system even with the very high sensitivity of the DI. Regarding your other question, no, I'm sufficiently happy with my Daedalus Ulysses that I don't envision trying any other speakers in the foreseeable future. See my post in this thread dated 6-10-2017. But I find it interesting to follow and occasionally contribute to the thread. And of course the comparison Chris (Waltersalas) is performing and reporting on between the DI and the Ulysses is especially interesting, as he uses or has used the same speakers, amplifier, phono stage, and phono cartridge as I do. Best regards, -- Al |
Vitop, absolutely do not connect the outputs of two power amps together, or to multiple binding posts on speakers that would in turn connect them together, even if both amps are never on at the same time. See the following threads, and the other threads and links provided therein. As you’ll see, possible approaches include speaker-level switching devices, and use of a single amp for the front left and right speakers in conjunction with the "home theatre bypass" function that is provided in many preamps and integrated amps. https://forum.audiogon.com/discussions/is-this-dangerous https://forum.audiogon.com/discussions/two-amps-to-one-speaker Regards, -- Al |
Bullitt5094 6-25-2017Very true. Also, even with an XLR cable it would be highly preferable to choose a cable having low capacitance per unit length (e.g., no more than around 25 or 30 pf per foot, and preferably less), and to drive the cable with a component having low output impedance (e.g., no more than two or three hundred ohms or so, and preferably less). However, given the several fine suggestions that have been made of suitably priced amps that provide only RCA inputs, I would seriously consider using one of those amps in conjunction with a Jensen transformer that would accept an XLR input and provide an output that would be connected to the amp with a short length of RCA cable. That may very possibly even work better than an XLR to XLR connection, because there is a substantial body of anecdotal evidence indicating that the sonic quality of the XLR input circuits of many modestly priced amps is inferior to the sonic quality of their RCA inputs. A suitable transformer would be the Jensen model PI2-XR if a stereo amp is being used, or a pair of PI-XR if monoblocks are being used. The PI2-XR is available here for $250. (That page shows a PI2-XX, having XLR connectors for both inputs and outputs, but you can specify RCA output connectors after clicking the "purchase" link). Further details can be found at the Jensen site. Good luck. Regards, -- Al |
You are thinking it would be cleaner to input any amp RCA from the Jenson piece?Not necessarily "any," but some and very possibly most, especially in the price range you are considering. Based, as I said, on anecdotal reports that have been provided here and elsewhere. And are you sure the transformer won't degrade the signal?I haven't used Jensen transformers myself, but a number of highly experienced members here who have **very** high quality systems have reported excellent results with them. I tend to lean toward a "less is better", minimalist view of a signal path.Likewise in my case. But there are exceptions to every rule, and I suspect this is one of them. And as you alluded to, the transformer may be simply taking the place of a low quality op amp device that is used in many designs to interface between a balanced input and an unbalanced internal signal path. Best regards, -- Al |
David_Ten 1-21-2018While I don’t profess to having a good understanding of the novel ZOTL output circuit which provides a transformer-like impedance transformation without using an audio transformer, it wouldn’t surprise me if the MZ2 does indeed "change its spots" significantly depending on the components it is being used with, and more specifically on the signal levels it is processing and the load impedance it is driving. For example, if the KT120 amp Tom used had higher gain than his and Charles’ 300B amps the 6SN7 output tube in the MZ2 would have been operating at higher signal levels in the latter cases, conceivably resulting in adverse effects on linearity and distortion. In any event, I suspect that Tom’s last sentence I quoted above pretty much says it all. Also, BTW, an experiment those using the MZ2 as a preamp may wish to consider doing would be to connect a resistor of say 4 or 8 or 16 ohms, rated to handle 2 watts or more, across the MZ2’s speaker terminals for each channel. I would imagine that would result in a significantly different sonic character compared to simply loading the MZ2’s output circuit with the vastly higher input impedance of a power amp, although I wouldn’t want to speculate as to whether the resulting difference would be for the better or for the worse. Best regards, -- Al |
Bullitt, while the description of the Candela states "low output impedance," it also states "output impedance <2Kohm." If the impedance is in fact close to 2000 ohms, that is much higher than I had suggested earlier would be optimal for use with most interconnect cable types at a 50 foot length. If the output impedance is in fact not much less than 2000 ohms, and if the length would be around 50 feet as you indicated earlier, what I would suggest (even if you use a balanced run via a Jensen transformer) would be a cable having capacitance of no more than 15 pf per foot for the 50 foot run, and preferably less. Otherwise perceptible rolloff and/or undesirable phase shifts are likely to occur in the upper treble region. Blue Jeans LC-1 (12.2 pf/foot) meets that criterion in unbalanced form, but as we’ve said earlier an unbalanced run of that length stands a good chance of having other problems. Off the top of my head, however, I don’t recall any balanced cables having similarly low capacitance that sell for similarly modest prices. Good luck. Regards, -- Al |
Audioman58 7-3-2017Actually, there are at least a couple of educated things that can be shared by those who haven’t heard them. One is that their specified sensitivity of 91 db/2.83 volts/1 meter, which for their 4 ohm nominal impedance corresponds to 88 db/1 watt/1 meter, combined with the fact that their impedance descends to 0.6 ohms at 20 kHz, would result in their being vastly less versatile than the DI in terms of amplifier selection. Another thing that can be shared is that they have a list price of $10K, obviously far more than the price of the DI. In any event, good luck with your new speakers. Regards, -- Al |
Mazikrav, the First Watt F3, F7, F1J, and F2J all have input impedances of only 10K, which seems kind of low for use in conjunction with a resistor-based passive preamp such as your Placette. Although the potential downside of that will depend in part on the output impedance characteristics of your source components, which I suspect are favorable in the case of your solid state Oppo, and probably also in the case of your Sound-Smith phono stage. But if you are considering going to a different amp, and envision staying with the Placette, it would be prudent to choose an amp having a much higher input impedance, e.g. 47K or more. Also, fyi, if your Sound-Smith "The Voice" cartridge is the model having a rated output of 2.12 mv, and if you are using one of Sound-Smith’s 43 db phono stages, you don’t have enough overall gain when using that source with the Placette to be able to drive the F3 (or the F7, or many other amps) to their maximum power capability, at least on the vast majority of recordings. Just some points to be aware of as you decide how to proceed. Good luck. Regards, -- Al |
Mazikrav, if the Guy Hammel preamp/buffer stage you referred to is this model, or is something similar in its impedance characteristics, it would certainly provide excellent impedance compatibility with just about any amplifier in existence. As well as with most source components, aside for certain tube-based models. But if it provides just a tiny bit of gain as you mentioned you still would not be able to drive many amps to their maximum power capability when listening to LPs. If you were to go to a significantly more powerful amp than the F3, though, the amp itself would **probably** provide enough additional gain for that to not matter, as it would probably put out enough power anyway. Generally speaking there is a **loose** correlation between the gains of various amplifiers and their maximum power capabilities. The F7 and many of the other higher powered First Watt models may be exceptions to that, however, because a downside of their minimalist signal paths is unusually low gain relative to their power ratings. For example, the F7 has a specified gain of only 14 db, while like most Pass Labs amps the XA30.8 which Kenny mentioned has a gain of 26 db. That means the F7 would require four times as much input voltage as the XA30.8 to provide a given amount of output power. That can be a significant issue in many cases involving the combination of a vinyl source and a passive preamp, or a passive preamp plus a buffer stage providing minimal gain. And the fact that the sensitivity of the Brilliance is about 5 db less than that of the DI just adds to the potential significance of that issue. When you develop a short list of potential amplifier candidates, let us know and this issue can be looked at more specifically. Regards, -- Al |
JCarcopo, when you use the switcher keep in mind that if a tube amp having output transformers is powered up and does not have speakers or equivalent load resistors connected to its outputs damage to the output transformers and/or output tubes can result. Especially if a signal is being provided to its inputs. Presumably the switcher connects its unselected inputs to nothing. Regards, -- Al |
Craigl59 7-8-2017Craig, the Dialogue Premium and Dialogue Premium HP power amps operate in class AB, aside perhaps for when they are putting out low power levels. That can be inferred from the relation between their rated maximum output power capabilities and the specified current ratings of their mains fuses (as indicated in their manuals), assuming a reasonable margin (e.g., 2:1) between the fuse ratings and the actual AC current draw that is anticipated. Given the maximum output power ratings of those amps, their mains fuses would have to have considerably higher current ratings than specified to support pure class A operation. Regards, -- Al |
@mazikrav, thanks for providing the additional info in your latest post. Assuming that the gain provided in the active buffer stage Mr. Hammel provided you with is similar to what is described in the Stereophile review you linked to, your initial statement that it provides little or no gain was correct. "Unity gain" = no gain. So per my earlier comments it can be calculated that when you are listening to LPs you cannot presently drive your F3 amplifier even close to its 10 watt maximum capability (for a 4 ohm load), at least on the vast majority of recordings. And the same would hold true with respect to the 30 watt capability of the F7. Fortunately it sounds like that isn’t a problem given your particular circumstances and listening habits. But I would suggest that if you go to a different amplifier it would be preferable to obtain one having substantially higher gain than the 12.5 and 14 db gains of those amps. Most amps having power capabilities comparable to the F7, or more, would provide that additional gain. As I mentioned, a downside of the design philosophy underlying most of the First Watt amplifiers is low gain. Finally, as added confirmation of all of this note the following comment by John Atkinson in the measurements section of the review you referred to: As specified, the Placette Active Linestage (ALS) offers a maximum gain of unity; ie, the maximum signal level is the same as that of the source components driving it. Owners should make sure, therefore, that their source components offer a sufficiently high signal level to fully drive their amplifiers.Good luck. Regards, -- Al |
Craigl59 7-16-2017I would respectfully but emphatically disagree with the use of the word "required." A more appropriate interpretation, IMO, would be that the specification of "400 watt power handling" provides a rough ballpark indication of the maximum amplifier power capability that is recommended as being reasonable for use with this speaker. Also, as Mac alluded to, for a given amplifier type and topology it can be expected that everything else being equal more amplifier watts = more amplifier $. Therefore for a given amplifier budget paying for watts that will not be utilized would in general mean that a higher percentage of that budget than necessary will go toward watts rather than sound quality. One of the reasons I chose my Daedalus Ulysses speakers, which like the DI have a very benign impedance curve, fairly high sensitivity, and high power handling capability ("recommended power 5 to 300 watts, peak power 600 watts +") is that I wanted the majority of my amplifier dollars to go toward sound quality, rather than watts. And even though I frequently listen to well recorded minimally compressed classical symphonic recordings which reach brief dynamic peaks of close to 105 db at my listening position, I have been very happy with my 70 watt VAC Renaissance amplifier. And perhaps its 30 watt smaller brother would even have been suitable as well, but I wanted to be sure that the margin between necessary power and power capability would be comfortable while not being excessive. Regards, -- Al |
Porscheracer, if you haven’t seen it already I would recommend that you take a look at a post I provided in this thread on 4-16-2017, in which I attempted to explain how the DI/MicroZOTL combo can provide SPLs approaching 100 db at typical listening distances, as has been reported. The post appears about 1/4 of the way down on this page. Now not having ever heard the DI or any of the LTA amps I can’t provide an opinion as to how that combo would sound when asked to do so. And as I alluded to in my previous post, for me an amp/speaker combination that can’t cleanly produce 105 db peaks at my 12 foot listening distance would be a non-starter. But as others have made clear in the preceding posts we have seen numerous reports of great results from that combo here, from highly experienced audiophiles, which leads me to have little doubt that for most listeners on most or all of their recordings the results would be outstanding. Regards, -- Al (Porsche owner) |
Hi Bill (Grannyring), My post attempts to explain how the DI/MicroZOTL combo can produce **peak** volumes approaching 100 db at typical listening distances, as has been reported here. Most listeners, of course, do not listen at average volume levels that are even remotely close to 100 db. And as I’m sure you’ll realize an average level of a more typical 80 db, for example, would require the amp to deliver an average of only 1% of the amount of power it would have to deliver to produce a 100 db peak. So my explanation takes into account the need to produce brief dynamic peaks that are much higher than the average level, for most listeners (not including me, as I said) on most or all of their recordings. Although as I said I can’t offer an opinion as to how the combo would sound in doing so. But in that regard I find the numerous experience-based reports that have been provided here to be compelling, and well within the bounds of plausibility. Best regards, -- Al |
First, kudos to Dave (Dlcockrum) for what IMO is an astute, perceptive, thorough, and exceptionally well written review he provided yesterday of his experience with David_Ten’s excellent system. And likewise with respect to the similarly well written comments provided by Laaudionut. Regarding inline attenuators, for many and probably most applications I would suggest going with the Rothwells rather than the Harrison Labs devices. Based on measurements I recall that one of our members provided here some time ago the resistor values used in the Harrison devices are low enough to be a problem in many systems. Especially if the attenuator is driven from a tube-based component which has coupling capacitors at its outputs. FYI, resistance measurements I’ve taken of 10 db unbalanced Rothwell attenuators that I have show that they consist of a 22K resistor in series between their input and output, and a 10K resistor in shunt between their output and ground. Therefore, depending on the input impedance of the component whose input they are connected to, the component providing the signal to them would see a load impedance in the rough vicinity of 30K or so. The corresponding numbers for the Harrison Labs attenuator are far lower. Re the gain questions that have been discussed, first, it’s probably fair to say that among the countless amplifier models that are available gain and maximum power capability tend to have a **loose** correlation. But many examples can certainly be found of lower powered amps having higher gains than higher powered amps. Charles, it can be calculated from the specified 0.7 volt sensitivity and 8 watt power rating of your Franks that their gain is approximately 21 db when their 8 ohm tap is used to drive an 8 ohm load. IIRC your speakers are nominally 14 ohms, and given the Frank’s output impedance of 1.8 ohms (as stated in a TAS review I’ve seen), their gain from the 8 ohm tap into 14 ohms would be close to a db more than that, or around 22 db. Re the Pass XA60.5, like most Pass amps it has a specified gain of 26 db, which corresponds very closely to what John Atkinson measured in Stereophile’s review of that amp. Correspondingly, it has a specified sensitivity of 1.1 volts for its rated output of 60 watts into 8 ohms. However its maximum power capability into 8 ohms (after transitioning from class A to class AB) is 130 watts per JA’s measurements, which can be calculated to require an input of about 1.6 volts to be reached. Best regards, -- Al |
Lpretiring, if the specs on the 2A3 amp you would be purchasing correspond to those of the 3.5 watt SET amp described in this Triode Lab datasheet (which is indicated as providing 4 ohm output taps), it can be calculated from the 3.5 watt power capability and the 500 mv specified sensitivity that the gain of the amp to the 4 ohm tap is about 17.5 db. The sensitivity of the Electron is spec’d at 95 db/2.83 volts/1 meter, which given its 4 ohm impedance corresponds to 92 db/1 watt/1 meter. So assuming these specs and those on your existing speakers are reasonably accurate (which is not always the case) you would gain about 5.5 db due to the speaker change and lose about 8.5 db due to the amp change, for a net loss in gain of about 3 db. Not a great deal, which on a typical rotary volume control, viewed as the face of a clock, corresponds to less than 1 hour of rotation. Also, while I haven’t looked into the specs of the Truth, the 100K input impedance that is indicated for the amp on the datasheet I linked to should be a fine match for most and probably almost all passive preamps. Good luck as you proceed. Regards, -- Al |
P.S. to my previous post: If the following page corresponds to your Truth preamp, it has an active output stage which in terms of impedance should have no problem driving pretty much anything. http://www.thehornshoppe.com/the_truth_pre_amp.html Good luck. Regards, -- Al |
Hi Charles, IMO a preamp having an active output stage but providing no gain should not be referred to as a passive preamp, but as you know terminology is often applied with varying degrees of looseness. And btw, I would infer from the page I linked to that it probably also has an active input stage. Best regards, -- Al |
Lpretiring, is the Truth that you have what is described on the page I linked to above? If so, its very low output impedance would make any reasonable load impedance (i.e., amplifier input impedance) a non-issue. Impedance compatibility issues, btw, if present may affect tonality, bass response, and other sonic characteristics, but would not affect volume levels to a significant degree. In any event, aside from certain unusual circumstances higher amplifier input impedances are preferable to lower input impedances, so 220K should be fine. I'm not sure what to make of your characterization of the unusual action of the Truth's volume control. But assuming as I said that the specs on everything are reasonably accurate you'll probably find that to achieve a given volume level with the new speakers and amp you would have to set the volume control higher than at present by an amount that with the present equipment would correspond to a small but readily noticeable volume increase. Regarding your more general question about gain, sensitivity, and power, the gains of the preamp and power amp, the sensitivity of the speakers, and the output level of the source component will together determine the position of the volume control at which a desired volume level is reached. Assuming, that is, that the desired volume level is obtainable without exceeding the amp's maximum power capability, or the power handling capability of the speaker. The power capability of the amp together with the sensitivity and other characteristics of the speaker and the room, as well as the listening distance, will determine the maximum listening volume that can be generated without the amplifier starting to clip and distort, as it starts to run out of power. The setting of the volume control at which that maximum volume capability is reached will in turn depend on the gains, sensitivities, and source output level I referred to in the previous paragraph. All that being said, in general the main concern I would have in using a 3.5 watt amp with 92 db/1 watt/1 meter speakers is not having enough power, rather than not having enough gain. For me that combination would be a non-starter (see my two posts in this thread dated 7-17-2017), but depending on listening distance, preferred volume levels, room size, and the dynamic range of the recordings that are listened to I'd expect it would be suitable for many listeners. Good luck. Regards, -- Al |
Hi Bill (Grannyring), I’ve had occasion to examine the waveforms and associated statistics of tracks from about a dozen or so CDs, encompassing pop, rock, and classical music, using a professional audio editing program (Sound Forge). Most did not have a single sample that reached full scale (i.e., the maximum possible digital value). A couple of them did, both being classical works having very wide dynamic range, but even in those cases that only occurred for a handful of brief instants during the course of a lengthy work. While on the rest of the CDs the maximum instantaneous volume of any sample ranged between a fraction of a db below full scale and many db below full scale. And I would expect in cases where the maximum sample value comes close to full scale that the original captures were made with much greater margins, and levels were subsequently boosted during the mastering process with software assuring that the maximum sample value would not reach 0 db. In general, I would expect that with the possible exception of some works having extremely wide dynamic range any reasonably competent recording engineer would make a point of not over-driving (exceeding the maximum possible digital value of) the A/D converter. So I would not expect the issue referred to in the ICC writeup to be much if any concern on the vast majority of recordings. Also, the major contributor to what is referred to as the "loudness wars" is not what is described in the writeup. That term is usually used to refer to dynamic compression that is intentionally applied in the engineering of the recording, to make soft passages louder and loud passages softer. That creates the perception of a louder recording than if dynamics were not compressed, and makes the recording better suited to noisy environments, such as cars, and more attention grabbing in such environments. So the bottom line seems to me to be that **IF** the ICC is implemented such that it does nothing unless samples reach 0 db (full scale) it will make no difference on most recordings, and only an occasional difference on the others. Best regards, -- Al |
Chris (@Waltersalas), regarding your possible purchase of a Lyngdorf, before doing so I suggest that you contact the manufacturer and ask what the input impedances of its balanced and unbalanced analog inputs are. Those numbers appear to be unspecified for the 3400, while the 2170 has no spec for its unbalanced inputs but a very low 10K figure for its balanced input. Which in turn suggests the possibility that its unbalanced input impedance **might** be only 5K, and if so it would most likely not be a good match for your Allnic H1201 phono stage (1.2K nominal output impedance), and perhaps also for your tube-based Lampizator Atlantic DAC (for which output impedance appears to be unspecified). Best regards, -- Al |
Cal3713, I agree with Charles that it seems evident that the 4 ohm DI impedance is a particularly benign one, with relatively little variation over the frequency range compared to most 4 ohm speakers, and little if any in the way of challenging phase angles. However two things can be said with a fair amount of certainty: Running the 8 ohm taps of your Franks into the 4 ohm impedance of that version of the speaker will significantly reduce the power capability of the amp, and will result in some degree of degradation of its distortion performance. And there certainly could be other sonic consequences as well. Personally, I don’t like the idea of introducing a known and likely significant compromise into the configuration of a system, on top of all of the unknown and unpredictable tradeoffs, compromises, and effects that are inevitably present in a system. And in a hobby where many concern themselves with things that are likely to be far less significant, even things like which way a fuse is oriented. Without a strong endorsement of the idea from Mr. Blume I would not even consider it. At least without the opportunity for an **extended** audition, and I would be hesitant to invest the time that would require given my suspicion that the result would stand a good chance of being negative. Best of luck, however you decide to proceed. Best regards, -- Al |
Porscheracer, some people have reported that using Rothwell attenuators has resulted in adverse sonic effects such as a reduction in perceived dynamics. Others have reported excellent results with them. I am in the latter group, having used the unbalanced 10 db version for several years, a few years ago. (My present system configuration doesn't require them). I suspect that a major factor in the disparities among these reports is the impedances of the components they are being used with. The worst case scenario figures to be an output impedance of the component providing the signal to them that is high and also varies significantly as a function of frequency, together with an input impedance of the component they are providing a signal to that is low. Regards, -- Al P.S: David_Ten, thanks for the nice comment. |
