The future of preamps

@ Swampwalker, Hi, Thankyou, you and Knghifi and a few others here on this thread, these few are gentleman indeed!, Audiogon needs more members like all of you! I am grateful.

Keith- If you want to contact Steve McCormack, you can do it thru this site (user name Stevemcx I believe) or thru his mod company SMcAudio. He's usually very approachable.

@ Knghifi, Wow!, Is steve still with mccormack in virgina?, seems he has his own company, from what I researched, the preamp you referred is something I have never seen before, no gain!, very different from any thing!, Have you had the opportunity to listen to smc preamp?

Audiolabyrinth, I doubt you will have problems with Atma-Sphere MP-1 driving your Krell. Still hesitant, a great alternative is SMC Audio VRE-1C. It's SS and competes with the very best tube pre. Send me PM for more details if interested.

@ Isochronism, Hi Brett, Thankyou for your kind words, Happy new year.

@ mapman, All that happened to the Krell 700cx amp I have was not the amp's fault at all, thats a whole other story by its self, the amp was working when I sent it to krell, just not working correctly, as a matter of fact, It was amazing the amp was working, Krell makes some tough amps!, As far as componets go at this point, The Krell appeared to be the best quality out of all the other poor, over priced equipment I had bad exsperiences with., Happy Listening.

Keith is a good ol' hospitable southern boy filled with passion and exuberance for our hobby. He and I have enjoyed many phone conversations so I attest to my statement. Keith, at some point you have to throw caution to the wind and trust the higher powers here. I am all for your soon to be realized audio success and fulfillment.

@ Mapman, Thankyou for your post, I am glad you can see how I feel, seems like every few steps I have taken to build this system, I have had to take more backwards!, very frustrating!, I am almost back to where I started from in April 2012!, this is the year I hope it works out better, however, At the cost of what I am tring to do, It will take some time for me to finish the system., cheers.

@ charles1dad, Thankyou for your kind words, I look forward to listening to a atmasphere m-1 preamp and the other models down the preamp chain Ralph has, cheers.

THis thread is a good example of why so few people are interested in high end audio, even if they love music and can afford it.

PEople just want their stuff to work and sound good, especially when making a sizable investment. Not be required to have a degree in EE in order to be able to cut through all the noise and be criticized when things go bad for whatever reason.

However hard it may be to figure out what works when things are going as they should, it pales in comparison to understanding why things break or malfunction or do not perform as advertised. All the facts needed to make such determinations are usually not known or apparent. That's why it's called an "accident".

Also why there is no substitute for good customer service, especially in an expensive hobby like this, and why no product can be successful over teh long term without it.

Audiolabyrinth,
You've had some unfortunate experiences with audio components. I wish you the best and hope this time around you have a sucessful outcome. I do hope you're able to hear the Atma-Sphere MP-1, you'll like it I'm certain.
Regards,
Charles,

OK, George and Knghifi- Point taken. I've got nothing to add technically to this discussion so I will retreat to the sidelines and lurk silently.

@ Atmasphere, Hi, I have said numerous times thru-out this thread how I respect you and like your designs, I hope you set the record straight with JWm and others here, they need to re-read some post!, Ralph, I have had alot of bad things happen to me in audio recently I have not disclosed on this thread, I apoligize if I was mis-understood, these mishaps that I have been thru costed thousands of dollars!, I was in no way at fault for what has happened to me, I have had a $6,350.00 tube cd-player blow up with-in 90 days of new, I have had tube products emit DC, I had to totally renew my amp at Krell!, that costed me $3,150.00 dollars!,the amp just came back in october,2013, Its still in the krell box, The good thing however, Is the amp got caps that was not available in 2005, Krell claims it is a better 700cx then when it was first made in 2005 or better than any 700cx amp out there, Krell said that, not me!, Krell claims I have the first and only amp like this, so in the end, I hope you understand why I am so worried about my investments!, nothing personal at all directed to you, and I would never be a person to give you a bad tiime after a sale unless I have litterally the same problems listed on this post!, Highest regards to you Ralph, Thankyou.

@ Georgelofi, Thanks, you hit the nail on the head with your post!, I love tube products!, I am just repeating what the service manager said to me at krell, that does not in no way make me the idiot!!!, I have no idea why JWm would put such a poor comment on this thread!, Very un-gentleman LIKE and un- called for!, I feel that Ralph's pre-amp is one of the best, why would anyone think I said something bad about him or his pre-amp?, I HAVE NOT!, Thankyou Almarg, very good valid point of your post, kinda looks bad for krell to write such things, cheers.

" I Think We're All Bozos On This Bus"
- The Firesign Theater

Swampwalker:
I have to set the record straight for you, not once have I trashed the sound of dc coupled output tube preamp. In fact as active tube preamps go it would sound the most transparent way of doing it, no coupling caps in the signal path on it's output.
Unlike 99% of most tube preamps that have coupling caps or transformers on their outputs to stop any dc from getting to the poweramps.

It's fact that if Audiolabyrinth uses it with a dc coupled poweramp like his Krell, should any fault cause dc on this preamps output, it will take out the Krell and most probably the speakers as well. As the Krell's engineer's have also had the same concerns.

As if a dc coupled tube preamp going faulty the dc offset on it's output is far more deadly than a solid state preamp going dc on it's output.

Audiolabyrinth just wants assurance that this will not happen to his prize Krell and speakers.

Cheers George

So far no one has pointed out the obvious so maybe it does not need saying, but a review of this thread and several others leads one to believe that George is "defending his turf" by talking trash about competitive active pre-amps.

Maybe it's not obvious that George is "defending his turf" so no one has pointed it out. Just 2 designers disagree on principles in building a preamp and is getting personal.

So far no one has pointed out the obvious so maybe it does not need saying, but a review of this thread and several others leads one to believe that George is "defending his turf" by talking trash about competitive active pre-amps. And I say this reluctantly, as an owner of one of his passive Lightspeed Attenuators. The LSA is in the opinion of many on this board (myself included), the biggest bargain in high end audio. However, it's not a replacement for a pre-amp if you have more than one source and it does lose out in SQ, to my ears, to actives at 10-20x the price. I do not have the technical know how to assess his claims vs Ralph's but if Almarg says that the marketing literature in the Krell manual is off the mark, then it is off the mark. He's an EE w no dog in this fight and a demonstrated track record of providing excellent interpretation of complex (to me anyways) technical and mathematical issues.

George, your generosity in making your product available at a bargain price and your intellectual property available to the DIY community is well known and exemplary. Unfortunately, you do not do your product or your reputation a service by trashing competitors. While many of us here know that you are "in the business", that should have been disclosed to the OP at the very least, to allow him to evaluate potential motivations.

This guy is either a troll who likes to talk trash about tube preamps or an absolute idiot. Take your pick. I think we should take votes. This is the most absurd thing I ever heard; Have the manufacture give in writing that his preamp will not sh-t on his tube amp. Maybe I should have my Dentist give me in writing that the new crown he put in my mouth will never fall off, never break, or never have to be redone in my life time. Absolute nonsense. Ralph I would not sell this nut a preamp if he stood on his head and offered you double the retail price. If you do I warned you he will call you every day saying something isn't quite right and he thinks DC is poising his pets.

01-02-14: Charles1dad
Al,
You are the man! At this point I don't know what more "need be said".
Charles,

Nothing more needs to be said, this is all simply a waste of cyberspace. Wc65mustang has this nailed down pretty well.

Al,
You are the man! At this point I don't know what more "need be said".
Charles,

I took a look at the statements in the manual for the Krell 700cx that pertain to DC. As someone having no dog in this fight, I would offer the following comments:

1)The relevant section on page 14 (pdf page 18) begins with the statement that:

The high DC output of tube preamplifiers may exceed the DC protection circuitry of Full Power Balanced amplifiers. Excessive DC level in a signal can damage amplifiers, speakers, or both. The coupling capacitors in Full Power Balanced amplifiers must be engaged when using a tube preamplifier.

Note that the statement does not refer just to tube preamplifiers having DC coupled outputs, it also encompasses the great majority of tube preamps that have coupling capacitors at their outputs. How are those preamps supposed to output "high DC"?

Also, note that when it refers to "the high DC output of tube preamplifiers," it does not make any reference to fault conditions. As if to say that all tube preamps routinely output high levels of DC, when operating normally. Which is nonsense, of course.

2)On page 19 (pdf page 23):

Q. My speakers are rated for 150 Watts. Are the Full Power Balanced 400cx or 700cx models too powerful for them?
A. No. A speaker seldom is damaged from overdriving. More often, damage occurs when an amplifier that lacks sufficient power is asked to handle heavy demand situations such as high playback levels. These amplifiers may have very high 8 Ohm power ratings, but in heavy demand situations they can be driven into clipping (in which DC current goes to speakers due to loss of amplifier power). Clipping can damage speakers.

This reflects a complete misunderstanding of how overdriving an underpowered amplifier can sometimes damage speakers. It has nothing to do with DC. The reason is that a clipped waveform has increased high frequency content relative to the original signal, which can damage tweeters.

All of the above doesn't speak well, to say the least, for the credibility of whoever wrote the statements in the manual cautioning against the use of tube preamps without the amp's coupling capacitors being in place.

3)I have participated extensively in these forums for more than five years, and I cannot recall a single instance in which an amp or speakers were reported as having been damaged by DC emitted by a tube preamp.

4)I second all of the comments by Charles about the credibility Ralph has established via his lengthy track record as a respected designer and manufacturer of very high quality equipment, and that he has further established as a result of his extensive contributions to these forums.

Regards,
-- Al

He's very transparent.
Audiolabyrinth, look at Atma-Sphere's stellar company track record with their products for decades.
Who's more credible Ralph or George in your opinion? Give it some rational thought.
Charles,

Charles1dad, it appears you are correct based on the post just above.

Audiolabyrinth go with your gut on this, as the Krell engineers have voiced their concerns about direct coupled tube output and recommended an input cap on the Krell.

I not the one trying to sell you anything, and I agree I would not like to put a cap on my dc coupled poweramp either to protect it, the best cap is no cap.

Second is why not give assurance if it's not an issue in writing, that it will not blow your Krell and probably your speakers as well, if it goes dc on it's output.

Cheers George

Ralph,
What more can you say to alleviate his concern? If he's not convinced of what you've told him he may never be, despite many years of safe trouble free (of DC issues) user evidence. I think George likes to get under your skin given his post above.
Charles,

You have rights to be cautious Audiolabyrinth about protecting your expensive poweramps, I agree get it in writing.

A tube pre if it's output is capacitor or transformer coupled gives some safeguard to precious large power dc coupled poweramps.

But if a tube pre is direct coupled and you get a bad tube or something goes haywire then your dc coupled power amps are in grave danger, even if the pre has output relays which can switch too late.

If something goes wrong, the dc offset in a direct coupled tube preamp premap can be up to 100 x larger that a transistor pre. Your poweramp may survive a dc coupled transitor pre going bad, but not a dc coupled tube pre.

Audiolabyrinth, George has no idea of what he is talking about here. I don't know of any tube preamp that is capable of doing the things he describes above, and that's after decades of making tube preamps with direct-coupled outputs. IMO he is trolling.

To put it more clearly, if the MP-1 did develop a fault, it could not make any high voltages as George suggests. We've been making the preamp since 1989 and FWIW it does not have a need for protection relays. It was designed to be fail-safe. To go 25 years like that should tell you something.

The preamp uses a patented circuit similar to what is used in our power amps. One of its advantages is that it is so reliable that it does need protection circuitry.

I hope that you understand that in order to stay in business, any manufacturer has to offer products that will not cause headaches down the road :)

I have already said why you will not find any manufacturer that offers 'documentation' regarding DC at their outputs. Put bluntly, the idea is preposterous.

IOW, George is wrong, this is not something you need to worry about. Its simply not an issue.

Another thing,
Consider the multitude of people who are using tube preamps with SS amplifiers and this has occurred for many years quite successfully. I believe your contact at Krell planted a needless bug of worry and anxiety.
Good Luck,
Charles,

Hi Audiolabyrinth,
If you heard the Atma-Sphere MP-1 I believe you'd absolutely love what it would bring to your system, I'd trust Ralph's assurances (he been doing this successfully a long while). But if you're that apprehensive maybe you should forget about using a great tube preamp.
Charles,

You have rights to be cautious Audiolabyrinth about protecting your expensive poweramps, I agree get it in writing.

A tube pre if it's output is capacitor or transformer coupled gives some safeguard to precious large power dc coupled poweramps.

But if a tube pre is direct coupled and you get a bad tube or something goes haywire then your dc coupled power amps are in grave danger, even if the pre has output relays which can switch too late.

If something goes wrong, the dc offset in a direct coupled tube preamp premap can be up to 100 x larger that a transistor pre. Your poweramp may survive a dc coupled transitor pre going bad, but not a dc coupled tube pre.

Cheers George

Wow, you can't make this up folks.

"Thick As A Brick"
Side Two

@ Atmasphere, Hi, I agree with you 100%, However, Do you have in writting that DC will not enter my amp under no circumstances of what problems that may occur with useage over a number of years?, I can attest that most tube preamps will put out DC when their is a major failure of some sort, LOL!, some brands damage other componets with-in a preamplifier when only the tubes run amock!, not saying your products do that, I have read numerous horror stories of this, right here on audiogon!, Keep in mind, I have, and will still be using particular tube products, To elaborate on this matter further, I have personally have had a respected tube product before, that in no way was suppose to emit DC, IT DID!, I used a volt meter, there it was, my amp was shutting off into stand-by all the time!, I believe your products may not do this, its out there thou!, I also wanted to ask you what a audio signal would be on a volt meter, I'm thinking, VOLts!, not DC?, thanks Ralph, Happy new year!

Audiolabyrinth, no preamp manufacturer would get very far if their preamp had DC at its output! Any preamp manufacturer has to deal with the fact that their preamp will be used with a transistor amp that is direct-coupled from input to output.

A DC level at the output can cause all sorts of problems, and not just for transistors. If a tube amplifier has a direct-coupled input (our amps do and many others do as well), a DC level at the input would cause the input circuit to make distortion and could adversely affect gain.

So it is simply something that preamps don't do! That is why I said earlier that Krell was promoting a myth.

Preamps, *all preamps*, do not have DC at their output. It does not matter tube or transistor.

So the Krell person you spoke to who is looking for 'documentation' need look no further than this post. No manufacturer in their right mind would make a preamp that puts out DC. It is literally that simple.

If you have it in writting in your manual or other wise that your preamp will not emit Dc at all, its all good to protect my investment!

Audiolabyrinth, I suggest hiring a team of lawyers to review the manual and getting it in writing. LOL!

I've used tube pre with ss amps for years and never had a problem. These are not your grandfather's tube pre. LOL!

@ Atmasphere, Thankyou for your reply,I will try to give you a phone call after new years to find out the closest place for me to hear your preamps and if you have documentation saying that your preamp will not emit Dc into a amplifier. Happy new year!

The volume control in the MP-1 is a custom-built switch with gold contacts and dual wipers to insure contact performance. It has 4 decks so we can control each phase (inverted or non-inverted) as well as both channels.

@ Atmasphere, Hi, Just got my call back from krell, they said, If you have it in writting in your manual or other wise that your preamp will not emit Dc at all, its all good to protect my investment!, He did want to know what kind of volume control you use, He also said, If its the old school pot volume control, it would not matter since you have dither controls for the gain, He said I should be able to ajust to match the amp, he preffered discrete attenuator volume control, meaning, has digital support, they veard off from the usual pot volume control for better out come of sound, what say you?, thanks Ralph.

@ charles1dad, Hi, I like you as well, you are a gentleman, I am tring to sort all this out and hopefully accomplish a match for my amp, Its sad I have to be concerned with what I do here, being Krell is saying repeativily about tube preamps with my paticular amp.

@ Atmasphere, Hi, I am really interested in your preamp to audition, I called my friend Ray Munchler, the service manager at Krell today, He said he would research your m-1 and give me his thoughts on useing it with my Krell 700cx, I like your circuit you designed!, no coupling caps, no transformers, Like to hear that, I know Krell is bias to solid state, However, Ray is going to give me his honest opinion on the matter, I believe no one knows Krell like krell does, His concerns is DC!, He believes before looking at your m-1, I may have to activate the coupling caps in my amp to use it, I will not do that, this will indeed degrade my sound performance, formost, you have been very nice to me and patient, Thankyou so much, you are a real gentleman here, you have my respect, I will let you know what Ray believes, happy new year.

I'm saying a preamp that has much lower output will play lower levels of volume that I like, most source I use are 2.5 volts output to 5 volts output, you said, times that by 5, thats to much volume, I like to turn the volume control to full setting and still have a little head room to the amps power with no distortions or clipping

If the volume control is working properly in the preamp the fact that it is set high or low will not affect the sound other than the volume itself. So you have no worries in that regard. What works in your favor is your amplifiers have relatively low gain, helpful if your digital sources have high output.

@ Almarg, Hi, I never said that preamp would not work with my amp, I'm saying a preamp that has much lower output will play lower levels of volume that I like, most source I use are 2.5 volts output to 5 volts output, you said, times that by 5, thats to much volume, I like to turn the volume control to full setting and still have a little head room to the amps power with no distortions or clipping, I have understood the both of you fully weeks ago!, I believe I was not understood, I do not want a preamp that cannot use all the volume control, LOl!, I enjoy music at times having a few to drink, maybe forget the volume, turn it up to full on the volume cotrol may propose problems for me, LOl!, I do thank you for all your help, and I have enjoyed talking with you and Ralph, maybe I may call Ralph after the new year, I find the both of you very interesting, Happy new year to the both of you gentleman.

@ Lacee, Great post, I agree with what you said, I to have had extensive exsperience with spectral equipment, I will say this much about spectral, very fast indeed and transparent, I could not find the full sound I enjoy with spectral, still good equipment, just not my tast in reproduction.

@ Grannyring, Damn, you have the the most profound modified Dude preamp I know of, I imagine it sounds wonderful, did you tube roll to?, If so, to what tubes did you use?

AudioL, ya my Dude has some parts I wanted for my tastes including Vishay Z Foil & Shinkoh resistors, Neotech top quality copper wire and 3001 cable for the signal path, extra power supply capacitance......

Nice Dude for sure!

Hi Audiolabyrinth,
Al and Ralph have given you a very "clear and correct" explanation regarding your concerns. Carefully re-read what they both have written.
Charles,

Al, let me remind you of a very fine album by Jethro Tull.
It's called "Thick As A Brick".
Gerald Bostock is alive and well.

Audiolab, I'll try this one more time, and then I'll cease and desist. The 32 volt spec is NOT A PROBLEM FOR YOUR AMP OR FOR ANY OTHER AMP IN THE KNOWN UNIVERSE.

Everything else being equal, the higher that number is the better. That number has NOTHING whatsoever to do with where you will set your volume control, and it has NOTHING whatsoever to do with how much voltage the preamp would be putting out in actual use.

How much voltage the preamp puts out depends on three things: The voltage that is sent into it by the source; its gain (which is a moderate 14 db in this case, for non-phono sources); and where the volume control is set. Again, where the volume control is set has NOTHING to do with the 32 volt number. Again, how much voltage the preamp puts out in actual use has NOTHING to do with the 32 volt number.

Please re-read the numerous posts Ralph and I have both made in this thread about specs on preamp output voltage capability.

Peace. Regards,
-- Al

I reaaly like the way the LSA allows the music to pass thru it without adding much.

I use it for my CD player,and I also run my Steelhead(volume at full)thru it.

I think the quality of the volume control can alter the sound of the system,and if you don't need any extra gain,why muck things up.

I do like the way some preamps can change the sound of a system and add more depth,or tone to the music,and I miss the things that my old CJ preamp used to do,even if those tricks were perhaps the result of distortions or were phase related.

All of audio is an illusion and we never know how close or far off we are from the reality of the original performance.

So in the end, we choose what distortions we want to live with or discard.

I've lived with many fine preamps from Levinson,Blue Circle, AtmaSphere, Conrad Johnson, Audible Illusions, Spectral,Meitner,RGR,Dynaco.

There will always be a future for preamps because of the colours that they can paint.
And that's not a bad thing.

@ Knghifi, Hi, I am interested in Atmas-phere, I have a problem with 32 volts out-put for a 3.58 input sensativity!, You can re-read my 12-26 post to Georgelofi and understand why, other than that, I believe the M-1 is a fine designed product on paper!, It would be nice to match perfectly, cheers, Happy new year.