danvignau-
I was thinking that you own Thiel loudspeakers as well?
I was thinking that you own Thiel loudspeakers as well?
How To Measure "Current" In An Amplifier?
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I've heard lots of times that an amplifier needs lots of "current" to drive a low impedance load.
Is there any measurement on a spec sheet that would measure current?
A high watts per channel amp does not necessarily mean that the amp has high current.
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I've heard lots of times that an amplifier needs lots of "current" to drive a low impedance load.
Is there any measurement on a spec sheet that would measure current?
A high watts per channel amp does not necessarily mean that the amp has high current.
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71 responses Add your response
The reason the MF M6Si can punch above its weight price/performance wise vis-a-vis other apparatus in its class is because its made in MF's own manufacturing facilities in Taiwan, to take advantage of skilled, lower-cost craftsmanship in that country, and efficient logistical connections with countries in the Asia Pac and Australasian regions. I have heard one and it is a stellar performer. |
I made an error and an omission. The Audire Forte and Parlando use 4 26000 mf filter caps per channel. Also, I want to hear about any impedence differences these designs might have. I have run B&W DM 14, 803 Series II and Acoustat electrostatic speakers,plus Peerless and 1259 subs with these amps. Only the 1259 subs did not work, maybe from lack of power; maybe impedence??? |
I can't help but notice that you guys keep mentioning damping factor as if it were an absolute measurement. If you look up on ebay, "Audire Parlando" ( 100, 200, 360 wpc @ 8,4,2 ohms), you will find a brochure for this amp. It lists the damping factor as 1000 @ 20,000 cps, 800 @ 1000 cps, and 500 @ 10 cps. I use a pair of slightly more powerful Audires (125 wpc @ ,8 ohms, 250 @ 4 ohms and 400 @ 2 ohms. It's damping factor is simply listed as 800. The pair of 500 watt transformers and 8 26000 mf filter capacitors per amp are the same, but the Parlando has a lot more output transistors, which lets it coast when my amps are working hard, but never to the point that it feels more than warm to the touch, even when just below the level to trigger the clipping indicators. Given nearly identical designs up to the outputs, at high volumes, the Parlando is smoother. That is why I run two Fortes, to let them coast (Sometimes; The power is cool with good wine, even better with cheap wine or too much scotch.) Any comments on either the three specs and the number of outputs as to current? My guess is that the Parlando could put out a lot more current if it had the transformers to do so.
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One of my older amps has these specs: 150 watts RMS continuous, 8 ohms 300 watts RMS continuous, 4 ohms 475 watts RMS continuous, 2 ohms Bridged mono: 550 watts RMS continuous, 8 ohms 800 watts RMS continuous, 4 ohms 1000 watts RMS continuous, 2 ohms Output Current: 40 amps peak, continuous 90 amps peak, 0.1 ohm, 20 msec, 1 kHz The ability to supply continuous current means a good power section, and the doubling into lower impedances also indicate a 'stiff' power supply. |
Mitch, Like all deeply technical factors in electronics, the question of 'current output' capability gets convoluted real quick. In assuming you're not looking for di/dt ratings (instantaneous current, like at the edge of a square wave), the average current over time would be as Al indicates. Al's approach of seeing what appears like a limiting factor at 2 ohms (potentially current limiting coming into effect) could be the best rule-of-thumb approach. Damping factor used to be used, but it brings in more uncertainties than it answers. The instantaneous current (di/dt) may be an answer to why some amps seem 'quicker' than others, or drive reactive loads better. In our work, we observe the difference between the current on the power rails vs. amplifier output current as a measure of the current drive capability. We do this with 2 high speed current probes and use the math function on the scope to produce a meaningful #. Depending on the amp type, this is a good indication when an amp is starved for current. I feel it would be a fair expectation that amp manufacturers specify current limit values for their designs. Like regulator chips and power supplies. Hypex does call this out on the nCore units we work with for example. I'm sure Bruno had something to do with that. |
Excellent discussion. I like looking at the amplifier bench tests that S-phile performs in their reviews to see if amplifiers live up to their claims. Most do, some do not - and some are truly overachievers. The O-scope does not lie! Since we're talking about current I am always impressed with the Parasound JC1s (which I own) performance and current dumping capabilities. "With continuous drive, the Parasound clipped at 545W into 8 ohms (27.4dBW)—way above the specified 400W. ("Clipping" is defined, as usual, as the power level where the measured THD figure reaches 1%, and is shown in fig.7 as the horizontal magenta line.) With a low-duty-cycle 1kHz toneburst more representative of music, the Halo was a powerhouse. Its clipping power increased by 0.3dB into 8 ohms, reaching 586.5W at 1% THD (27.7dBW, fig.7, black trace), with 1154W available into 4 ohms (27.6dBW, blue), 2255W into 2 ohms (27.5W, green), and no less than 4.2kW into 1 ohm (27.2dBW, magenta). The latter is equivalent to an output current of 64.7A!" 65 Amps is a LOT of juice!! |
Good find, Hal, as the review makes clear that the design of the M6si draws significantly on the design of the M5si, and the relevant specs that are provided for both are not greatly different. The total gain of its line-level and power amplifier sections can be calculated from the specified 270 mv sensitivity for a 150 watt output (presumably into 8 ohms) as being about 42 db. That is somewhat highish, but not unreasonably so, and given also the 91.3 db/2.83 volts/1m sensitivity of your speakers as measured in the Stereophile review (which corresponds to about 88 db/1 watt/1m in the mid-bass and lower mid-range regions where speaker impedance is around 4 ohms) seems consistent with the lowish volume control settings you are using. Especially if you are using digital sources, that typically have higher output levels than an analog phono stage would. Possible indications of too much gain are overloading of circuitry that precedes the volume control in the signal path, which would manifest itself as obvious distortion, and depending on the design of the volume control mechanism the possibilities of excessively coarse resolution of volume adjustments that may occur at low settings, introduction of channel imbalances that would not be present at higher settings, and some degree of sonic degradation. But you would almost certainly have already perceived these kinds of things if they were occurring to any significant degree. As far as power and low impedance drive capability are concerned, I note the following in the M5si review: Rated at 150W/8ohm, the latest in Musical Fidelity’s ’super integrated’ amplifiers achieves 2x165W/8ohm and 2x265W/4ohm with 200W, 355W and 545W possible under dynamic conditions into 8, 4 and 2ohm loads, respectively.... While its output into the lowest 1 ohm loads is protected at 275W or 16.6A ... the M5si still looks capable of grappling with any likely partnering loudspeaker.And I note that for a 2 ohm load the 16.6 amp figure corresponds very closely to the 545 watt maximum dynamic (non-continuous) power capability that is indicated. So while the design falls significantly short of doubling its continuous power capability into 4 ohms relative to 8 ohms, and the considerably higher capability into 2 ohms appears to be limited to intermittent dynamic demands, it seems to me that the compromises that were introduced into the design in the interests of keeping the cost at the desired level were chosen judiciously and intelligently. Especially in the context of an application such as yours where the speakers have a combination of reasonably good sensitivity and the ability to handle copious amounts of power. Best regards, -- Al |
Back to current.... While it has been noted in this thread that Musical Fidelity does not publish 4 ohm stats (at least in the case of their M6si), I note that a very recent review of their M5si (one step down from the 6 but certainly related/comparable) is packed with data about amperage, including into 1 ohm. It behooves me to draw an inference from this review to M6si. Further, if Musical Fidelity or other manufacturers are not disclosing or otherwise providing this type of data, clearly there is some objective means of measurement given that "professional" reviews do state specifics. http://www.analogueseduction.net/user/products/large/M5si%20Hi%20Fi%20News%20April%202016.pdf |
@charles1dad I appreciate that feedback Charles. I suppose too much gain could be the case, however, my previous post indicating 1 watt and approx 90 db is more or less by ear only. I haven't used any kind of metering. And while I believe those numbers to a rough approximation, as I consider it further it may be a bit less db like somewhere in the 80s (and therefore less wattage too). But it is loud. Many times I've referred to the decibel scale (average home 50, vacuum 70, chainsaw 110, pain 130) or even different descreptions like this http://www.noisehelp.com/noise-level-chart.html lead me to believe I'm in the ballpark. And, I would add two things. One, not in all cases does the 9 o'oclock position sound loud. I have ran across some source material where I need to go to 10 or 10:30 just to get what I normally would from 9. Second, the volume control does allow for what I'll loosely categorize as "high precision" around the 9 o'clock range. For instance, if I go from 9 to 9:15 or from 9 to 8:45, the difference is noticeably louder or softer respectively. So without the intention of hijacking this thread, how would "test" or know if they have to much or too little gain? |
@almarg to your point "None of which means, BTW and IMO, that your amp isn’t a fine match for your speakers :-) " Absolutely. I’m going further to say I have found a great match. Stereophile review of the Triton 1 indicates "As tends to be the case with a design using a passive high-pass fi lter with a fairly low corner frequency, the electri-cal phase angle becomes increas-ingly capacitive below that frequency; although the impedance magnitude rapidly increases below 100Hz, miti-gating the effect of that phase angle, there is still a combination of 4.1 ohms and –50° at 100Hz, which will require a good 4 ohm–rated amplifer to drive the speaker to acceptably high levels." In the meantime, despite the fact that Musical Fidelity does not publish a 4 ohm spec for the M6si, casting doubt as indicated previously in this thread as to its ability to drive a low impedance load by virtue of, presumably, high current, I can tell you that under normal listening I can get the Triton’s singing at the amps 9 o’clock volume control position. Basically producing about 1 watt or 90 db at that point. Cranking to 12 o’clock you wouldn’t be able to have a conversation with a person sitting next to you, much like a night club playing outrageously loud. So unless Stereophiles meaning of "high levels" corresponds to the Who’s record breaking concert ear piercing decibel threshold, I can vouch that the M6si > Triton 1 "match" is outstanding if we are speaking in terms of (point of this thread) "driving low impedance to high decibel levels". |
These reviews indicate the Musical Fidelity can do 440 watts into 4 ohms and 800 watts into 2 ohms. I’m not stating that is or is not true, but IF true, would that support the 45 peak-to-peak amperage claim (or the RMS conversion to 15.9)? And, to the point of this thread, that it can "easily" drive a low impedance speaker?'Yes' to the latter, no worries. To the former, 800 watts into 2 ohms is 20 amps. Thats 56.6 amps peak to peak. If that is so, why would they state that 45 amps peak to peak is the spec? |
Hello Al,Hi Charles, Yes, that’s true on all counts. Not surprisingly I found that the zero feedback setting sounds best, although the difference between that setting and the lowest one or two possible feedback values (of five that are provided, in addition to the zero feedback setting) was fairly minor. "Not surprisingly" in part because the impedance of the Daedalus Ulysses has exceptionally little variation over the frequency range. Lou Hinkley hasn’t ever officially published an impedance curve, as far as I am aware, and I haven’t ever seen published measurements of its impedance characteristics, but I recall him commenting in a post elsewhere that the nominal 6 ohm impedance varies within a tolerance of +/- 1 ohm at all frequencies above 100 Hz, and gradually rises to about 10 ohms in the bottom octave. Best regards, -- Al |
Hi Hal, For a resistive load: Power = (Current Squared) x Resistance = (Voltage Squared) / Resistance 15.9 amps into 4 ohms = 1011 watts 15.9 amps into 2 ohms = 506 watts 42 volts RMS (the amp’s maximum output voltage rating) into 4 ohms = 441 watts 42 volts RMS into 2 ohms = 882 watts FWIW my guess is that the 4 ohm and 2 ohm power numbers stated in the review and the dealer writeup you linked to, which roughly correspond to the 42 volt max output rating, were informally provided to those parties by MF (since those numbers do not appear to have been officially published by MF), and I would guess that they do not represent what the amp can do **continuously.** I note also that the dealer writeup includes the word "peak" just after the mention of 800 watts into 2 ohms, which casts some doubt on the meaningfulness of that number. Also, the SoundStage review mistakenly says "MF claims that the M6i can pass 45 amps peak current." What MF claims is 45 amps peak-to-peak, which for a sine wave or other waveform that is symmetrical above and below zero corresponds to 22.5 amps peak. None of which means, BTW and IMO, that your amp isn’t a fine match for your speakers :-) Best regards, -- Al |
Hello Al, Your Daedalus speakers are designed to work well with either tube or SS amplifiers. Your VAC REN 70/70 amplifier provides a choice of several NFB settings and zero feedback. I'm assuming that you have tried the various feedback settings, which one sounds best with the Daedalus Ulysses? Thanks, Charles, |
Gdhal 9-26-16Not sure if it answers Ralph's question, but FWIW it appears that the 220 watt capability of the amp into 8 ohms is voltage limited, not current limited (or thermally limited, for that matter). The manual indicates that the max output voltage at the onset of clipping, across the 20 Hz to 20 kHz frequency range, is 42 volts RMS, which corresponds almost exactly to 220 watts into 8 ohms. Best regards, -- Al |
@almarg and @atmasphere These reviews indicate the Musical Fidelity can do 440 watts into 4 ohms and 800 watts into 2 ohms. I’m not stating that is or is not true, but IF true, would that support the 45 peak-to-peak amperage claim (or the RMS conversion to 15.9)? And, to the point of this thread, that it can "easily" drive a low impedance speaker? http://www.goodsound.com/index.php/component/content/article?id=153:m http://www.stereofil.no/stereo/integrerte-forsterkere/musical-fidelity-m6si |
Very high Damping Factor doesn't make much sense since most of the speaker's impedance is resistive. For 8 ohm speaker it would be about 6 ohms. This resistance limits actual DF to 1.3 In order to prevent amp from making it worse 0.8 ohm output impedance would be fine (10% change). Max current specification may suggest amplifier current limit but it doesn't specify the load impedance and doesn't say what happens with supply voltage. Even amplifier with very weak power supply might be able to deliver high momentary short circuit current. AFAIK speaker impedance usually dips around few hundred hertz (first crossover frequency). Music on the other hand carries the biggest voltage peaks at the lowest frequencies. |
Using the previously posted example (fig.4): http://www.stereophile.com/content/conrad-johnson-lp125m-monoblock-power-amplifier-measurements#xxGh... adds to the confusion. |
Atmasphere, forgive me but I'm still confused:-). Are you saying for instance that: a ss amp rated as 100 Watts into 8 Ohms = 200 Watts into 4 Ohms and 50 Watts into 16 Ohms. and a tube amp rated as 100 Watts into 8 Ohms = 100 Watts into 4 Ohms and 50 Watts into 16 Ohms. and that's why tube amps are more expensive? |
Gdnrbob 9-26-16Hi Bob, No, I didn’t say that. Or at least I didn’t mean that :-) I suspect you are referring to this statement: I’ll mention also that once damping factor gets above say a few tens (in other words, away from tube amp territory) I would not expect much if any correlation between damping factor and performance into low impedances.Tube amps often have damping factors in the single digits (i.e., less than 10), and in some cases even less than 1. The highest damping factor I can recall ever seeing for a tube amp was in the vicinity of 25 or so. While of course solid state amps commonly have damping factors in the hundreds, and sometimes even above 1000 (especially in the case of many class D amps). I read a Wikipedia page explaining it, and it sounded like a high damping factor allowed an amp to control a speaker cone better than a low one.Speakers vary widely in the amount of damping that is optimal, not only in terms of "control" but with respect to the tonal effects resulting from the interaction of their effective output impedance (which is inversely proportional to damping factor, as Erik indicated) with the speaker’s variations of impedance over the frequency range. The majority of speakers are of course designed these days with the expectation that they will be used with solid state amplifiers, and those speakers will perform well with amps having relatively high damping factors. However once the damping factor gets above a few tens (arguably as little as 20, but 50 or 75 so would seem to be a safe ballpark) further increases in damping factor will **in themselves** make little or no difference in terms of both control and tonality. I say that despite beliefs to the contrary that are prevalent among many audiophiles, and claims to the contrary that can be found in a lot of marketing literature. Many other speakers, though, are equally happy or even more happy with tube amps having low damping factors. It depends on the intention of the designer, as Ralph has said in a number of past threads. And some speakers are equally happy with tube and solid state amps, and with high or low damping factors. In those cases the intrinsic sonic character of the particular amp can be determinative of which is most optimal. So how can a high damping factor be bad? 1)It may be a poor match for the particular speaker, the result being too much damping and "control," and/or tonal balances that were not intended by the designer. As Erik indicated, a low damping factor, corresponding to a high output impedance, will result in output voltages from an amp that may vary significantly as a function of a speaker’s impedance variations over the frequency range. However some speakers will sound best when that variation **is** significant, i.e., when the variation of amp output as a function of load impedance variations results in power being held closer to constant than voltage. See Ralph’s paper on that subject. 2)High damping factors (and also very low total harmonic distortion) are accomplished in some designs by means of heavy-handed application of feedback, which can result in objectionable amounts of transient intermodulation distortion (that is not normally specified, and for which measurement standards do not exist), and/or increases in certain harmonic distortion components that are particularly offensive (even though **total** harmonic distortion may be reduced). Hope that clarifies more than it confuses :-) Best regards, -- Al |
Your saying that tube amps halve their power as impedance is doubled? Isn't that what ss amps do?Yes, it is. Maybe the way to look at this is the 8 ohm power. With a tube amp that is 35 watts, it will also be 35 watts into 4 ohms, and if the impedance of the load is double will then be 17 watts. With a solid state amp that makes 35 watts into 8 ohms, its output into 4 ohms might be 70 watts, so 35 watts into 8. This is what I meant about tube amplifier power being more expensive. |
@atmasphere "Regarding your amplifier, the specs don’t add up as presented so there is more to the story. The 45 amp figure seems to refer to output. Converted to RMS as Al did (so it makes more sense) the 15.9amps does not gel with 220 watts. Into 8 ohms at 220 watts the current is 5.24 amps. The 15.9 amp figure makes more sense if the load impedance is slightly less than 3 ohms. At this point the amp would be making a bit over 660 watts. Does that sound right to you? " I agree at face value the numbers don’t add up. I have sent a question to Musical Fidelity, but wouldn’t hold my breath for a response. To your point "IOW you still have to take it home and see how it sounds, even after all the measurements!" Yes, I wholeheartedly agree! This is kind of what I was trying to convey to Erik earlier in this post. What remains so puzzling, amazing and interesting to me after so many years in this hobby and "knowing" so much LESS than so many members in this thread is how after all the reading is said and done, and the actual listening begins, how the ears belie so much of the experience one gathers during the reading of these threads. As the Grateful Dead would say, "if you get confused, listen to the music play". |
OK, but even with that feedback, unlike many ss amps, the vast majority of tube amps can't double down/halve up with varying speaker impedance and the corresponding varying sensitivity, and I would assume therein deviate from linear frequency response and ergo(?) distort timber, no?No. What happens, and this is the part where we see that tube amplifier power is more expensive, is that the amplifier makes its full power into the lower impedances, and makes less than that (for example, 1/2 power into 8 ohms as opposed to 4 ohms) into higher impedances. With a solid state amp, we are used to seeing it double power as impedance is halved. The difference here is that a tube amp is going to make its normal power into the **lowest** impedance, while the transistor amp is going to make its normal power into the **8 ohm** impedance. I can see how this could be really confusing, so the other way to look at it is that in both cases the amplifier has to act like a voltage amplifier, which is to say that it will be constant power into all frequencies presented. Since the tube amp can't double its power as impedance is halved, instead it cuts its power in half as impedance is doubled. Either way you get flat frequency response. The real question is, 'Is flat frequency response important to the human ear?' which is another question entirely and the answer is 'sometimes'. The problem is that the ear converts any form of distortion into some form of tonality. The brain has tipping points where if there is enough distortion it will favor that sort of tonality over actual frequency response (whether flat or not). This is why some amps can sound bright and others not even though on the bench they measure exactly the same frequency response. The brightness can be caused by a tiny amount of higher ordered harmonic distortion or by IMD. This is why speaker/amplifier matching is still a thing, even though speakers are **supposedly** voltage-driven! IOW you still have to take it home and see how it sounds, even after all the measurements! |
@unsound That doubling/halving is exactly dependent on output impedance. :) So, more feedback = less deviation = less aparent output impedance. :) And, that's what you see in the two charts. The tube amp has more frequency dependent variability than the solid state amp. This is the sort of thing you get into when you think about speakers that are more or less tube friendly. :) The higher, and flatter the impedance of the speaker, the flatter the amplifier's output. Best, Erik |
Erik, I wasn't quoting you saying High DF was bad, only referring to Almarg's response that a high DF would wreak havoc on tube amps. Though if you could elaborate why, I would appreciate it. Thanks for your replies, but I am still a bit confused. Ohms, watts, and voltage, I get, but this Damping factor still kind of eludes me. |
@unsound Take a look at the top chart from Stereophile: http://www.stereophile.com/content/conrad-johnson-lp125m-monoblock-power-amplifier-measurements#ETgE... Notice the squiggly black line (called grey in the text)? That’s what happens when an amp with high output impedance drives the varying load a speaker presents. The frequency response of the amplifier goes up where the impedance of the speaker goes up, and down where the speaker impedance goes down. Compare this to an amplifier with very low output impedance: http://www.stereophile.com/content/theta-digital-prometheus-monoblock-power-amplifier-measurements#Z... There is still some variability, but it's MUCH less than +- 1dB. :) Mind you, I make NO claims one amp is better than the other. :) This is a pure specmanship so far. I am not sure given the chance to own either which I would prefer. Best, Erik |
@unsound With very high output impedance the frequency response of the amplifier looks like the speaker impedance. I.e. not flat! :) With very low output impedance the frequency response of the amplifier stays flat. The missing step: Increasing feedback reduces the amplifier output impedance. That and lowering distortion are why most amplifiers have at least some feedback incorporated into the design. |
@unsound Feedback improves DF = lowers output impedance = less variability with output voltage. :) Output impedance can be thought of as a resistor at the outputs of the amplifier. With a perfect amplifier, this resistor is zero, and the voltage at the speaker is always the voltage at the amp. However, amplifiers are not perfect. Batteries are like this too. Looking at a AA battery, you model it as a 1.5V source, but in reality it has a rather large output resistance. So whether your flashlight sees 1V or 1.3V has to do with how much current is drawn and how big that output impedance is. The more old-school your flashlight, the more current, and the more V will be lost in the output impedance. But modern LED bulbs sip current, so most of the batterie's V will appear at the LED terminals. Confused yet? :) Erik |
Damping factor is usually measured as (8 Ohms / output impedance). So an amp with 100 df has an output impedance of 0.08 ohms. 20 has around 0.4 Ohms. The higher the apparent output impedance (i.e. the lower the damping factor) the more the Voltage response will track the speaker impedance chart, instead of reamining flat. By the way, adding feedback essentially improves damping factor. The normal way to improve df without feedback is to use massive banks of parallel output stages. Best, Erik |
Atmasphere, If I may: wouldn't that variable impedance load provide for a less linear frequency response and resulting timber distortion than the steadier impedance load of the Thiel via tube amplification?You may! :) The answer though is 'no'. The variable is how much feedback the amp has, not whether its tube or not. Its not going to take a lot of feedback to get the voltage response needed for flat output on Erik's speaker. My guess in looking at the curves is that about 6 db is all that's needed. Most tube amps with feedback have more than that. |
HELP! I was following this thread, I thought, pretty well. But, Damping factor came into play. I read a Wikipedia page explaining it, and it sounded like a high damping factor allowed an amp to control a speaker cone better than a low one. So, what makes having a high damping factor bad? Sorry if this is something obvious... Bob |
@atmasphere Thanks for the clarification. If you don't mind, I may quote you when I recommend the kit. :) Since I don't build tube amps, I'll defer to your mastery of the subject. By the way, the LM-1 is a free-to-build kit in honor of my hero, Dr. Marshall Leach Jr. All the design docs are online and I make no money at all when someone builds the kit. Best, Erik |
@erik_squires It is NOT tube friendly like the Thiel. Notice the 24 Ohm peak in the bass and 16 Ohm impedance peak where the woofer and tweeter response meet.Actually your speaker looks a lot more tube-friendly than the Thiel. The issue here is 'will the amplifier produce a flat frequency response with the given load?" and if the tube amp has a damping factor of 20 or so, which is easily achieved, the answer in your case is 'yes'. In addition, it will do it with lower distortion and greater power than it will with the Thiel. This is simply because the Thiel requires the use of the 4-ohm tap of the amplifier driving it, and the 4-ohm tap is not as efficient as higher impedance taps, has less bandwidth and greater distortion. Your impedance curves strike me as benign insofar as tubes are concerned. The amps we make are low or zero feedback, but I would give them much better chances at driving your speakers than the Thiels on account of the impedance. Its more important for impedance to be high than it is to be flat. Regarding your amplifier, the specs don't add up as presented so there is more to the story. The 45 amp figure seems to refer to output. Converted to RMS as Al did (so it makes more sense) the 15.9amps does not gel with 220 watts. Into 8 ohms at 220 watts the current is 5.24 amps. The 15.9 amp figure makes more sense if the load impedance is slightly less than 3 ohms. At this point the amp would be making a bit over 660 watts. Does that sound right to you? |
Erik, thanks for the link, interesting, and I really do like your writing style! Much of this is technically over my head. With that said, and playing Devil's advocate: might it be possible that in that links reference to the original cross-over design when coupled with an appropriate amp; that the idea was to strengthen bass response? When one can get measurements like this: http://www.stereophile.com/content/dunlavy-audio-labs-signature-sc-vi-loudspeaker-measurements#k4pSB... does it really matter than it drops to below 3 Ohms? I would think that there are plenty of amps that wouldn't be too bothered by it. |
Erik, MF does include the damping factor in their specs, and I posted it earlier, 180. As you do not care for the overall match between MF and GET, I'll ask your opinion then on what speaker you believe would match to the MF, and what amp you believe would match to the GET. What I can tell you is I do have pretty good hearing, and am a member of an audio club on Long Island so I have the good fortune to listen to quite a few VERY expensive systems (components like Bryston top-of-the line amps, Alta Statement Tower speakers with an MSRP of 200K, Magnepan speakers, many other kinds of amps, etc. Many years ago (without disclosing my age :) ) while Eddie Layton (organist for NY Yankees and musician) was still alive, I would regularly listen to his then top-of-the line McIntosh setup (amp, preamp, speakers, source component, etc. all MAC), which at the time (late 70's early 80's) was valued at over 100K. So after listening to numerous systems throughout my lifetime I can tell you besides the fact that I'm rather pleased with the overall sonic performance of the MF and GET combination, I have yet to hear a better sounding combination of amp and speakers at their combined price point of 8K.. |
