DK Design VS.1 Reference mkII - Optimization

I found that tube rolling made a big difference, but the choice of tube preference depended on equipment and also personal preference in sound.

Also, I found that leaving it on virtually all the time made a big difference. It takes many hours to warm up. To play it in the morning turn it on in the evening.

Art

I have to agree with Art it sounds much better when left on. Besides tube rolling (I use Mullards)I put ERS cloth around and on top of the transformers which helped flesh-out the midrange and opened the soundstage noticeably. Check out www.Tweekgeek.com for the ERS cloth.

Sbayne, interesting especially considering the didgital metered display which may be a source of rfi interacting with the transformers.
On the inside rear panel, do you think the speaker output wiring proximity to the preamp tubes might cause any interactions?
Also stock power cord or? Mine did not come with the factory ac cord so I am needing to find something synergistic that moves the performance in the right direction.

Jomoinc, ERS cloth on the output wiring may help - I will may try that. The power cord makes a significant difference too. I was using a ZCable Cyclone for awhile which sounded VERY nice which it should since it cost more than the amp. I now use a ZCable black lightning which solidified the bass a little more and took that last bit of edge off the upper mids and lower treble which may have been tube glare in my system. I've also used SignalCables basic power cable on it which was ok but it didn't control the bass as well as the ZCable black lightning.

One tweak that I tried that makes a BIG difference is playing the amp with the cover off. When the cover is on, electromagnetic waves bounce off the metal and back into the amplifiers circuitry. When the cover is off, you will be surprised how much better it sounds.

07-06-06: Audioari1
One tweak that I tried that makes a BIG difference is playing the amp with the cover off. When the cover is on, electromagnetic waves bounce off the metal and back into the amplifiers circuitry. When the cover is off, you will be surprised how much better it sounds.

And you know the difference in sound is attributable to the electromagnetic waves bouncing off the top cover? How do you know this for certain? Could it also be possible that the amp runs cooler with the top off, and therefore the bias is at a different level than when the top is on? Having done bias measurements on my Class A/B solid state amps immediately upon removing the top cover (after the amps had been on for several hours), and then measuring again 45 minutes later when the amps were cooler, I know for certain the bias was different...and the amps sounded different.

Tvad, I am fairly certain that it is not due to the cooling effect because the amp doesn't get very hot in the first place. And it makes logical sense that the electromagnetic bounce effect is at play here. In any case, whatever you want to call it, the DK amplifier sounds substantially better with the top cover off, try it and see for yourself.

Audioari1,
I also have found that the amp sounds better with the cover off.Regards,Bob

And it makes logical sense that the electromagnetic bounce effect is at play here. In any case, whatever you want to call it, the DK amplifier sounds substantially better with the top cover off, try it and see for yourself.
Audioari1 (Threads | Answers)

Honestly, electromagnetic bounce effect sounds like pseudo-science to me, but if the DK sounds better with its top off, then top-off it shall be!

One way to achieve the best sound and still have a cover for your DK is to have one made from Lexan. It is a clear material, so the cover will be see through, but it wont have the electro-magnetic bounce effect like the aluminum cover does. I think that DK really dropped the ball on this detail because really it sounds MUCH better with the cover off.

This may be a dumb question but I believe tubes need biasing (dont know what that means though).

Anyway, do designs like DK and BAT and McIntosh offer a feature where the biasing is done automatically since I'm quite apprehensive of doing this myself. Unless someone here can convince me that it's easy and hassle free.

Thanks

Art, when you say leave the amp on, do you mean on power or on standby?

This is so far, the most polite discussion about DK Design Group products I have ever seen in the forums. This is a nice change for the better.

07-06-06: Audioari1
One way to achieve the best sound and still have a cover for your DK is to have one made from Lexan. It is a clear material, so the cover will be see through, but it wont have the electro-magnetic bounce effect like the aluminum cover does.

Aluminum is non-magnetic, just like Lexan, so there should be no difference in performance between these two materials. Plastic (Lexan) encourages static electricity, so it seems to me the aluminum cover would be the better choice.

Tvad, What is needed is a magnetic cover - that will absorb those electro-magnetic waves and they won't just bounce about in the amp. If you don't believe in electro-magnetic waves or fields just look for the Aurora Borealis. Maybe there is a look alike in the amp that only appears in the dark. ROTFLMAO, but not at you. :-)

Audioari1, can you provide a link to an article discussing electro-magnetic bounce effect?

I have done a search for "electro-magnetic bounce effect" and found nothing. I have found several articles discussing electromagnetic field radiation, and ground bounce, but these are two separate phenomenon, and ground bounce is controlled by the adjusting size of wire traces.

Here's the article

Work in progress....My speakers don't really allow me to turn up the volume much past the 9 o'clock position with out involving the neighbors and I also noticed the lack of heat produced and decided to try something to see if it improved the performance. In the past my MC275 tube amp sounded ok at lower levels but really started performing at the higher volume levels. Anyway I have a sony cd with an adjustable output so I simply dropped the input signal and cranked up the DK to the between the 11 & 1 o'clock positiion to see if hopefully it works a little better. I think I may be on to something.....
Does anyone have any info on what the pots on the preamp board relate to? I remember reading something about the adjustablity of the input...
The meter is not as entertaining but I am thinking at this point that it sounds better.....

Tvad, I am telling you the amp sounds better with the aluminum cover off. In an industry where people use little pebbles, roller blocks, and expensive power cords I find it surprising that you should have difficulty accepting that the aluminum cover degrades the sound of the amp while a Lexan cover does not.

Also, while aluminum is non-magnetic it still will bounce more of the EMI then a Lexan cover will. If you shoot an electron into an aluminum plate the results are very different then if you shoot an electron into a Lexan plate.

Audioari1, I'm not disputing the effects you hear, and I would like to learn more about the electromagnetic bounce effect (EMBE) to which you attribute the difference in sound. There a dozens and dozens of amplifiers, preamplifiers, and CD players that use aluminum cases and covers, and I have never before read about the deleterious effects of aluminum as it exacerbates EMBE. If EMBE is a cause of less-than-ideal sound, and if it's effects are so apparent, it seems to me there would be far fewer components utilizing aluminum cases for improved shielding.

With your help, I'd like to understand this better.

I'm assuming you have read somewhere about the electromagnetic bounce effect, how it bounces more readily off some materials than others, and how it relates to the performance of audio components. Since I'm trying to learn more about physics and audio, any link or reference to an article/study about electromagnetic bounce effect would be appreciated.

Have you ever considered taping a sheet or two of ERS paper (ERS blocks EMI/RFI) to the inside of the cover of the DK and listening for any difference?

I have not tried ERS paper, but one manufacturer that supplies a lexan cover instead of an aluminum one is DartZeel. Their amplifier, as you can see in a lot of literature, is supplied with a clear cover specifically for that reason.

Maybe shoot an email to DartZeel to explain this effect in more detail?

Also, while I believe that almost all components sound better with the aluminum cover off, this effect is especially prevalent in the DK amplifer where the difference is quite dramatic.

07-07-06: Audioari1
I have not tried ERS paper, but one manufacturer that supplies a lexan cover instead of an aluminum one is DartZeel. Their amplifier, as you can see in a lot of literature, is supplied with a clear cover specifically for that reason.

I did some research on the Dartzeel website, and they do use a clear cover, although it is made of glass (according to their white paper).

Interestingly, they do mention the benefits of a glass cover over a metal cover:

And contrary to metal, glass is totally transparent to magnetic fields, thus avoiding the inherent magnetic loop that metal would induce over the power supply transformers. Last but not least, the internal housing is much less polluted my magnetic ghosts

Ironically, the Dartzeel amplifier's case is made of aluminum:

The case of your machine is ezclusively machined from AW-5754-ALMG3 alloy aluminum. offering a remarkably even surface and hardness

Why use a glass top and an aluminum case if aluminum is an issue for reflected EMI? EMI doesn't know about direction...it radiates 360 degrees...not just up. Why not make the case out of ceramics, plastic or carbon fiber? There are a few non-magnetic, non-reactive material.
Since aluminum is non-magnetic, I'd still like to learn how it could induce a magnetic loop.

By removing the cover you will have changed the mechanical mass of the entire chassis.Vibration and it effects on the circuitry will also have been changed. Vibration influences can greatly alter the spectral balance. The amp has been retuned within its own environment. Tom

Tom, Your explanation is as good as any I've seen for the reason this amp sounds best with the top off. Tubes are microphonic to some degree and the less vibrations (from any source) the better. Removing the top would certainly eliminate one potential source of vibrations. I've done this with some CDP's/Dac's and pre-amps.

I just don't understand these electro-magnetic 'waves'comments.

Apparently the amp generates a lot of EMI which must then be disappated in some fashion and taking the top off facilitates that disappation. But if the amp is creating the EMI in the first place, and its harmful to the signal, it seems to me as if the damage is already done.

If the EMI is externally produced it seems that having a non-ferrous case, including top, would be beneficial in keeping it out of the amp. I also don't understand the 'wave' concept, I can understand EM fields of changing intensity, but 'waves' which bounce back and forth off some surfaces but not others? Are you aware of any science which supports this?

Tvad, Audioaril, Tom, anyone - please help me to understand this.

I also don't understand the 'wave' concept, I can understand EM fields of changing intensity, but 'waves' which bounce back and forth off some surfaces but not others? Are you aware of any science which supports this?

Tvad, Audioaril, Tom, anyone - please help me to understand this.
Newbee (System | Threads | Answers)

I sure can't, and that's why I'm not convinced EMI effects are the reason Audioari1 hears benefits with the DK top off. If Tom's vibration theory is correct, then why would the amp sound better with the top off? More vibration causing additional microphonics in the tubes? I have heard some claim that microphonic tubes...just below the threshold of causing ringing and echo...sound more spacious and open, and therefore "better".

Audioari1, in what ways does the DK sound better with the top off. Would you please describe what you hear?

Tvad, I'll take a stab at the vibration/top issue, by way of example. I have a CDP with case vibrations induced by the transformer. These vibrations are sufficient to rattle the tube innards which increases any potential they have to be microphonic. When I take the top off the CDP I'm eliminating one of the surfaces which facilitate the transmission of the vibrations. Often the audible (as well as physical) frequency (pitch if you will) and intensity of the vibration changes - usually lessens. Mass loading can have a similar effect.

If you have the best LN tubes and your unit has a low noise floor you might not actually change anything except reduce the audible transformer hum (not a bad thing at all), but if you have borderline tubes and a highish noise floor these vibrations can induce tube microphonics which can be audible. FWIW, I think there are better ways of getting 'spacious and open' than using microphonic tubes. :-)

I think I misunderstood Tom's point. I thought he was suggesting that removing the top increased vibration due to a less rigid case structure (which is the case in automobiles...coupes being more rigid than convertibles in the same models), when it appears Tom was suggesting that removing the top decreases case vibration. Sheesh, I'm confused.

I don't know whether to remove my Magic Fingers motel bed from my listening room, or to keep it in.

Hey guys my thoughts were that removing the top changed the vibrational pattern and therefore the sound...for the better or for the worse. I am very comfortable with myself knowing that vibration can be given a pattern as well as direction in all things that are in motion, which is everything. Removing the case which is more likely less massive than the main chassis would probably reduce the amount of various resonance points that could be transfered back to the main chassis and electrical components to be reamplified in the mix. Most of you know my previous history and thoughts ..mass loading versus mechanical direct coupling..anyway the case removal altered the vibrational direction and flow..Proper mechanical grounding of all the boards, transformer and power supply caps to the main chassis and all of this direct coupled to a greater mass {the floor of your home} would transfer vibrational energy away from and out of your component..The result would be greater resolution and dynamic scale. So I have experienced.. Tom

07-08-06: Theaudiotweak
Hey guys my thoughts were that removing the top changed the vibrational pattern and therefore the sound...for the better or for the worse.

Indeed.

I dont think vibration is an issue with the DK amp. It is a very massive peace of equipment and there is no vibration to speak of. This brings me back to the EMI issue. The concept is quite simple, some of the EMI bounces off the aluminum cover and goes back into the circuitry, creating a sort of a negative feedback circuit. When a small amount of signal goes back into the circuitry it gets amplified again. This is the reason I believe the amp sounds better with the cover off.

What I hear is that the midrange becomes even more open and organic when the cover is off. There is also a bit more detail and texture in the bass.

If you believe it sounds better with the top off, then that's all that matters in your system.

Electrons vibrate regardless of mass. If there was no motion their would be no sound. Giving that motion focused direction and relief is the key to better sound and greater efficiency. Tom

Tvad, you are absolutely right.

Knowing the real answer to why? may greatly increase the application of the answer. Tom

Sbayne,
I went to the Zcables website and was reading the Black Lightning info and noticed that they "do not advise the 12AWG for amps producing over 200 watts non didgital" I emailed and received a reply from Mark Hampton stating that high current amps may benefit from a larger AWG. "The more complicated answer it that sometimes amount of current is the most important thing for power amps, and sometimes quality of current is."
Do you or anyone else know what the DK provided ac cable AWG was? Anything unique about it? Also other owners...what power cable are you using with this amp to benefit its performance?

I'll lay heavy odds that a 9awg power cord of any brand would be noticeably better on the DK than a 12awg cord.

The DK amp is supplied with a regular computer power cord, such as the one that comes with most Dell PCs. I had several discussions with DK regarding this and they are simply selling the amp and circuitry at the lowest possible price with a cheap power cord and tubes which they believe are user upgradeable. Also, the previous owner, Daniel Khesin, was not a big believer in power cords, although he heavily emphasized upgradingthe tubes.

Also, the previous owner, Daniel Khesin, was not a big believer in power cords, although he heavily emphasized upgradingthe tubes.
Audioari1 (Threads | Answers)

Mr. Khesin's opinion doesn't carry much weight these days.

I have tried several power cords with my VS1MK11.
Guerrilla audio, Signal cable,Supra Lorad 2.5 VirtualDynamics power one. For my ears the VD is the clear winner. When it comes to ic's i haven't tried as many, Mas silver,Zsquared copperheads, VD audition, once again the VD was the the best for me.
I was talking with AGON member that had his VS1MK11 modded by Parts Connexion they change over 85 parts. He said it was huge upgrade from the stock amp!! even at the 1k price.

Jomoinc, yes the Black Lightning is "only" recommended up to 200 watt amps but I would totally agree with Mark that its the quality of the power cable not the AWG that counts.

Sbayne, I was thinking also about the "integrated" issue with both the preamp and the power amp being fed at the same time from the same hose, er... cable.
Hey in relation to the modified VS1MKII I wonder if the Parts Connexion could modify it to separate it up to provide for an external preamp power supply and as long as we're dreaming, how about a separate amp only input! Somebody stop me!!

I mean that I leave power on. Standby helps but it's not enough. I'm guessing, hoping, that the tubes have a low current and will last a long time (change annually?)
Art

If I recall correctly I used the top of the line Audience power cord with the DK. Not sure but I think so.
Art

The Eichman Power cord with Mullard Tubes. Synergistic Alpha Quad Active's at the bottom and Guerrilla Audio Silver for the top end in a bi-wire configuration. The transformation is absolutley amazing. The bass and mid-bass response is now among the best I have ever heard anywhere at any price. Does anyone have a short list of materials that would be considered acoustically and electromagnetically inert and a better choice for the cover?

Brass of course..And then proper mechanical grounding of all the boards, power supply caps, transformers and then the entire chassis. Vibration either self induced or of external influence can be given a positive relief to a higher mass..ground. Tom

Theaudiotweak: Brass? That's a surprise, I would have guessed rubber or wood or maybe glass or plastic. Do you also feel that the metal screen transmits electromechanical vibration and or electromagnetic induction? It seems like the metal screen would be a good electromagnetic sink or do you feel a polyester screen would be preferable?

Theaudiotweak: Brass? That's a surprise, I would have guessed rubber or wood or maybe glass or plastic. Do you also feel that the metal screen transmits electromechanical vibration and or electromagnetic induction? It seems like the metal screen would be a good electromagnetic sink or do you feel a polyester screen would be preferable?

The removal of ferrous materials in and around circuit boards, crossovers and speakers will result in lower distortion and a more musical presentation. Providing vibration direction,focus and relief in my experience results in a much more natural, dynamic, and open sound. Brass is my material of choice in most every instance. Tom

Mullard CV2492 gold pin cryo tubes . Somebody talk to me who has rolled a set of these into the preamp. I presently have a set of Tungsram E88CC/6922 and did not see a substantial change from stock tubes. What cha got there...?

I do most of my serious listening with vinyl and did a phase test with the Shure test recording TTR-110 through the phono and input A and the phase was reversed. I flipped my speaker cables red to black, black to red,to correct this. FYI- I use Silver Sonic Q-10 speaker cable presently connected to full range dipole speakers (Hunt Janni Tombstones-DIY). I am looking for my test CD to check the input I use for CD play (mostly background music as my setup is in my living room......

Hello Malbor,
You mentioned you have a friend that has done the Parts Connexion Upgrade to his DK. I have been considering having this done for quite some time and have never, until now, found someone who can give me their opinion with the outcome. Without being rude, is it possible to pass on my email to your friend? Thanks.

Oh, and just so that you know, I was one of the first to buy the DK (and I don't mean that in an Al Gore/internet kind of way) but was very pleased with its sound right away. And in the early and quiet beginnings of this amp had many conversations with Daniel. And while listening to his enthusiam about using the supplied powercord and interconnects, those items didn't make it a day beyond their break-in with my system. While this is a beautiful amp, it's not a plug and play amp and, as with any personalized audio system and component, will greatly benefit from a thread like this.