"Pre-amps 101"

[StereoNut]

If you haven't already read my mention of it under my NYAL Moscode 600 thread, I will preface this new topic with my goal here.

I want to explore the possibilities of which pre-amps will sound the best with my NYAL Moscode 600 amp once it returns from the one and only Mr. George Kaye.  I am leaning towards Tubes, but haven't eliminated SS completely.  At the same time, I don't want something with dozens of glowing glass bottles for the upkeep factor or anything that uses some exotic $$$ megabuck hard to find tubes for the sanity factor.

I haven't clicked the "post" button yet and I can already hear the outcries from the forum balcony...  I know what the saying is about opinions being like @ssholes... and needing to listen to new equipment in MY system to truly evaluate it.  I know... I know!!!  The problem is that I need an education on pre-amps in general, before I even start to contemplate which ones I should try to audition.

Essentially, what are the differences, benefits and/or drawbacks of Passive vs. Active, Zero Feedback vs. with feedback, etc... and what else needs to be considered in matching a Pre-amp to an amp and the rest of one's system???

Hopefully, a few of you will post your thoughts here and I can officially consider class in session for "Pre-amps 101".  All I ask is to keep the technical stuff in easy to understand form for the "techno-challenged" like me!

So, enlighten me... please.

Thanks!

[BobM]

You do need to make sure that the output impedance of the preamp works properly against the input impedance of the amp.

According to the general guidelines, your new preamp should have an output impedance 1/10 or less of the load (or the amp's stated input impedance). So if the amp's input impedance is 100K ohms (which is generally where they land), then the preamp's output impedance should be 10K ohms or less (which is easy to find).

I know my amp (DNA 500) has a rather low input impedance of 10K ohms, so I needed a preamp with a rather low output impedance (most tube preamps are pretty high) and I found a good one with only 220 ohms output.

As for tubed vs passive vs solid state ...
- My preferance is that you need tubes somewhere in the chain, so with a SS amp you would want a tubed preamp, but with a tube amp you have more choices
- Passive preamps are beautifully transparent, but may not (generally) be as dynamic as a unit with gain. That transparency is addictive though and you will be hard pressed to find a regular preamp with gain that is as transparent.
- SS will generally have a lower noise floor than tubed units (blacker background).
- Tubed units will generally have more bloom than SS
- Don't worry overly much about feedback. That's just a designers choice at lowering noise floor specs and if done properly should not be a negative thing.

[StereoNut]

Thanks, Bob!  

Of course, nothing can be easy with me... my NYAL Moscode 600 is a hybrid, so where would that fit in this audio jig-saw puzzle?

Here are some tidbits of info. that may help you.

  "In 1984 New York Audio Laboratories was the first company to introduce the first hybrid tube/fet tube amplifiers and preamps, and we called them Moscodes; a name that was a combination of Mosfets and cascodes. Cascodes is the name of the configuration of tubes we used for gain stages.

...the importance of active regulation in tube circuits is decades old: All of the Moscode amplifiers featured completely independent and regulated power supplies for the tube front end. The Moscode 600 was quite special because it used tube regulated power supplies, for the front end of each channel featuring the same regulator tube used in the Futterman circuit. Not only were the Moscode amplifiers the first hybrid tube/fet amplifiers, this was the first time that tube regulation was used on a tube/mosfet amplifier. Again….This should remind you that I have been singing my "tube regulating tubes" song for at least twenty years now…because this creates an elixir of harmonic ecstasy."

The whole (?) story by Dr. Harvey "Gizmo" Rosenberg that I took the above quotes from is here:
http://www.meta-gizmo.net/tri/nyal/moscode.html

[topround]

Bill,
You were(are) a Naim person correct?
That would mean you drank the Naim coolaide for a while.
No offense, Naim makes very nice gear, but companies like Naim and Linn and others of course try to get you to buy all their gear. Sort of hypnotize you and make you forget the rest of the audiophile crazy world.

Sticking carrotts in front of you with endless expensive upgrades.  I understand it well, and by the way it is brilliant marketing genius, which can also yeild great results at times.
But in the end you really have overpaid for a power supply that should have originally been incorporated into the original design. But those scotts are very ingenius fellows.

So that makes you new to the next level of audio insanity....synergy
It is elusive and can get expensive, but sometimes you can get lucky!

If you become like us , who do not believe you have to have every component designed by the same fellow, you will find you have to find a good match between the various compnents.
Unfortunately you will have to find out what works best with your gear. Moscode 600 ...not many users of that design these days, so a body of knowledge would be hard to find.

You are looking for a full function pre with phono....a bit difficult.

I think a separate phono is the way to go, but I take phono very serious,for  others it is just another source, and not their prime source, like me.

Most full function phonos have a compromised phono section, so if you do not use phono a lot get a killer line stage and work your way up the fono food chain. Great fono can be  expensive.

For full function you might try
Quicksilver
CAT
Rogue
Rowland(SS)

I mentioned the TRL Dude and the First Sound pre before, these are more money and non phono, but they would be the heart of your system and your preamp search would be over unless you have 30K plus to spend on a pre, at that point the Ypsilon pres are the best I have heard to date, they just smoke everything

[StereoNut]

Bill,
You were(are) a Naim person correct?
That would mean you drank the Naim coolaide for a while.
No offense, Naim makes very nice gear, but companies like Naim and Linn and others of course try to get you to buy all their gear. Sort of hypnotize you and make you forget the rest of the audiophile crazy world...

Yes, Mike... I am the "Naim guy".  I have finally decided to move on from my Naim gear and re-configure my system.  I am trying to accomplish things with a somewhat systematic approach, replacing gear one piece at a time.  And, yes I agree with you.  The one single most important word in audio system building is synergy.

The "foundation" of my system will be my three (3) latest acquisitions: a pair of 2012 Mod. Von Schweikert VR-4 Gen.III speakers that I just had upgraded earlier this year, my NYAL Moscode 600 amp (once I get it back from being freshened up by George Kaye) and an original version Eastern Electric Minimax DAC.  Somewhere along the line I may (?) look into a better CD transport, but my old Cambridge Audio D-500SE CD player with the EE DAC is sounding really nice on the digital side via a Black Cat Veloce BNC <>BNC cable.  Same for my Linn LP12/RB300/Adikt combo for analog... it's fine, for now.

With all that being said, a new (most likely used) Pre-amp is what I feel my next priority should be.  Which is why I started this thread in the first place.  My Naim pre-amp & Power supply sounds pretty good with the Moscode 600, but I feel there's a lot more music to be had with a better pre.

The only reason I've been leaning towards a pre with a phono stage is to try to keep things simple.  It would eliminate the need for another power cord and set of I/C's for an outboard phono and I felt it would be the more economical approach overall.

I appreciate everyone's recommendations here, but also realize I need to learn more about the differences in the types of Pre-amps out there to be better prepared to narrow the choices down a bit and focus on what pre's will have the best chance of having good synergy with my Moscode amp and the rest of my system in general.

The quest continues... actually, it's just beginning!

[DaveC]

Do you have a computer w/DAC? If so, hook up your DAC right to the amp and lower the volume using the music server software. Do you have enough gain going direct from DAC to amp?

Probably yes, in which case adding a preamp with gain would be pointless. You can still get an active preamp with no gain, but most digital sources have very low output impedance and should be capable of driving a passive pre.

My Aikido preamp with 20 dB gain drives my SET amp with an input sensitivity around 20V RMS, about 20x the input sensitivity of most amps these days... IMO most amps have way too much gain. If the amp has that much gain, might as well make it an integrated... 

[topround]

I guess you should get a  feel for your amp when you get it back. listen , burn it in and be honest with yourself, try to find the things you like and dislike about it. I have bought geaR  I thought I loved only to be honest with myself later on and sell it.

I wish I could help you, at your budget it is difficult to get everything, and of course buy used, no one pays full retail for anything these days...really.

The Dude goes for about under 3K used as well as the First sound, they are on my short list for a preamp for myself, I actually heard the Dude in my system and was shocked.

As a reflection of todays econimic situation used gear is not selling very well and new gear hardly at all, so sometimes great deals can be had if you hold out or play hard ball, people are holding on to their cash, or converting it to metals,(Ilike silver) so offers are far and few between making it a good time to buy something used, people are willing to be beat up a bit, the alternative is no offfers and no cash.
Good Luck you may get a good deal on something

[BobM]

There's a few goodies on Audiogon right now that might float your boat...but how do you know they will work with the Moscode? If you can get them lowballed it might be worth a chance, but you may have to wait 6 months or so to resell if not.

Herron VTSP 1A ($1350)
http://app.audiogon.com/listings/tube-herron-vtsp-1a-166-as-new-original-owner-2012-11-04-preamplifiers-14051-swormville-ny

Presenmce Audio ($1480)
http://app.audiogon.com/listings/tube-presence-audio-line-stage-1-tube-pre-see-photo-2012-11-04-preamplifiers-ontario

a few different Audio research pre's in at your price point

Modwright SWL9 ($1295)
http://app.audiogon.com/listings/tube-modwright-swl-9-0-signature-edition-silver-2012-11-02-preamplifiers-94602-oakland-ca

[StereoNut]

I guess you should get a  feel for your amp when you get it back. listen , burn it in and be honest with yourself, try to find the things you like and dislike about it. I have bought geaR  I thought I loved only to be honest with myself later on and sell it.

I wish I could help you, at your budget it is difficult to get everything, and of course buy used, no one pays full retail for anything these days...really.

The Dude goes for about under 3K used as well as the First sound, they are on my short list for a preamp for myself, I actually heard the Dude in my system and was shocked.

As a reflection of todays econimic situation used gear is not selling very well and new gear hardly at all, so sometimes great deals can be had if you hold out or play hard ball, people are holding on to their cash, or converting it to metals,(Ilike silver) so offers are far and few between making it a good time to buy something used, people are willing to be beat up a bit, the alternative is no offfers and no cash.
Good Luck you may get a good deal on something

I gotta tell you that you're making a lot of sense here, Mike - which is great.  The only chance any of us have in fighting "nervosa" is holding fast to common sense as best we can.  I can't promise I won't do something stupid and buy a pre to try before my amp comes back, but waiting (as you recommended) is what I really need to do.

As far as budget goes, your Dude & First Sound suggestions scared me off by looking at their MSRP's. BIG $$$ there.  I didn't realize their re-sale #'s are as "reasonable" (under 3K) as you say.  Is it a lot more than my $1000.00 > $1200.00 budget, YES - but they're not impossible #'s.  (If I could save for my Von Schweikert upgrade, I can save for a pre!)

So, I will do my best to be patient (yeah right... when was the last time anyone seriously used audiophile and patient in the same sentence! ) and wait for my amp to come back.

Thanks for your comments & suggestions!

[StereoNut]

Dave

Thanks for the suggestion, but I don't have any sort of computer audio set up.  (I'm honestly not ready to make that leap right now.) Hopefully, I will be able to sift through all of the ideas here and start to narrow my choices down.

Time will tell!

[StereoNut]

There's a few goodies on Audiogon right now that might float your boat...but how do you know they will work with the Moscode? If you can get them lowballed it might be worth a chance, but you may have to wait 6 months or so to resell if not...

That is the bottom line, Bob... unless you're working with a retailer (for new equipment) that offers in-home auditions of his display items, none of us normally have the luxury of "try before you buy".  Audio Advisor is the only other choice I can think of (30 day? in-home) but again you're talking about spending NEW gear dollars. 

I'm hoping that once I get my Moscode amp back, I can bother all of my fellow Syndrome members for as many pre-amps that I can borrow for an audition in my system.  Does it mean I get to listen to every pre-amp on the planet?  Of course not, but it's better than buying completely "blind".  The hardest part will be being patient.

There goes that word again... patience!

[richidoo]

Hi Bill, fun stuff for you.

According to this thread:
http://www.diyaudio.com/forums/tubes-valves/220403-moscode-600-tube-recommendations.html

Your amp has a lot of tubes in it already. 6922s are very tasty, can be chosen to sweeten things nicely, if that is what you want. So you don't necessarily need to add more up front. I'm not a big fan of 6FQ7 follower, but I think there are subs for that, I used 12AU7 for that, you have to ask George what will work if you want to swap that.

Because your amp has tube input stage, it will have very high input impedance 100k+, so virtually any preamp source impedance will work OK. Some of the best sounding tube preamps have higherish output impedance (>600ohms,) but others in that category are very very low. Manley Jumbo Shrimp is only 50 ohms, so it can drive any amplifier with ease. I think there is one of those on Agon now. It is a warm but very nice sounding preamp, good features, good USA build, great service, great resale. The jumbo is clearer sounding than the original Shrimp.

If you want more transparency then you can use 9 pin tubes, if you want to sex it up with some phat 2nd and 3rd order harmonic distortion then look for octal (8pin) gain tube like 6SN7 family. 6H30 is a modern (1970s) Russian 9 pin tube made famous by BAT and Audio Research, it has excellent technical specs, sometimes called the "Supertube" but it depends on the circuit. In Moscode 402 amps I like 6922 better, but 6H30 sounds awesome in newer generation AR preamps like Ref 3 and later. Those are complex circuits so there is a lot more than the tube in play with AR.

I have always loved the octal sound, especially a 6922 gain with 6SN7 follower even better. Cary uses that combination to great effect, and they made a few mid priced preamps.

If I were in the market for preamp I would buy a deHavilland UltraVerve with remote. Member Clearsound in NY is selling a demo unit. Maybe you can audition that. I don't know if it has low output impedance, I might tend to doubt it.

When it comes to preamps, the best sounding units tend to cost more. SURPRISE!!! I hunted for a $1000 tube preamp once, and settled on EE Minimax. My Tutay modded unit sounded very good, very powerful and low distortion (20V into 600ohms!) but it made some EMI hum due to the small chassis size and it was a little thin sounding for my system at the time. I was craving 6SN7. Since then I have heard a lot more $1k tube preamps and have not been impressed.

I agree with Mike, an internal phono stage will compromise the phono stage and even the line stage to keep price down. If you do get a tube preamp, pick one that has a passion for excellent musical sound quality, not features or price.

Kara Chafee on feedback:
"Q: What is the story with zero feedback?
A: The Aries 845 amplifier uses no feedback loop or "negative feedback" at all.  This is probably the most difficult way to design an amplifier, because the amp has to sound good just the way it is. Feedback was traditionally used to lower distortion and improve the tone of an amplifier-for example if you remove the feedback from most audio amplifiers, they sound "yelly" or have a tunnel kind of tone. With a carefully designed triode amplifier you spend endless hours matching and understanding the strengths and weaknesses of each component in the amplifier, until it sounds balanced and natural without adding feedback.  The benefit then is that the amplifier sounds more open, immediate, dynamic and natural. Feedback tends to homogenize the sound."
http://www.dehavillandhifi.com/Q&Akara_chaffee.htm

Nelson Pass on feedback: http://www.firstwatt.com/pdf/art_dist_fdbk.pdf

If the amplifier is designed to have low distortion and low impedance without feedback, then it will sound better without it. Negative feedback screws up the math, even a couple dB. But there are other kinds of correction that don't screw up the math, witness HCat, Spectron, paX, etc.

Line level tubes are usually linear enough to be relatively easy to design simple circuits without feedback and still sound good. A few dB of feedback around a stage might help it sound even better, or worse. All solid state preamps have a LOT of feedback, except maybe the diy stuff from Pass. An opamp has 100dB of feedback, even more than a Bryston power amp! You can hear it easily, even though it is .00001% THD, the infamous LM4562, the music killer. Preferred by test bench audio designers and reviewers and spec worshippers everywhere.

[rollo]

Bill the preamp is a very important decision. The heart of the system.
   Wether passive or active the impedance of such is key. The amp if 100K input is very versitale in accepting most all preamps. the output impedance should be a minimum of 10 times the inpur impedance of the amp used.
   Now a passive pre may be the ticket but there are requirements to use such. First the CDP or DAC must have a output voltage of 2V minimum. The input sensitivity of the Amp must be below 1 volt. Makes a nice match then with volume and gestaht. I would try a Slageformer or another trannie based passive.
    As far as a phono/pre vs linestage. I would consider a linestage only with separate phonostage. Just more options for the future upgrade path with cart and TT.  Besides the Linn you have just loves its own Linn phonostage.
   Which way to go is dependant on what you are trying to achieve sonically. Do you want a neutral pre ? Warm ? bright ?Dark ?
    One needs to determine that first to narrow the chase. So budget first then character then try away.
   On my shortlist is the Gary Dodd  [ battery powered]preamp, Dude, Response Audio, Miracle Audio, CAT. For SS Klyne, Rowland, Parasound [J.Curl design]. For passives, Slagle, Bent Promithius.
    The reason for the sepate phono is the ability to match your CDP and TT with the linestage. Killing to birds with one stone. A phono/pre may limit the TT and or CDP.
 Hope that helps.


charles
      
    

[DaveC]

When it comes to preamps, the best sounding units tend to cost more. SURPRISE!!! I hunted for a $1000 tube preamp once, and settled on EE Minimax. My Tutay modded unit sounded very good, very powerful and low distortion (20V into 600ohms!) but it made some EMI hum due to the small chassis size and it was a little thin sounding for my system at the time. I was craving 6SN7. Since then I have heard a lot more $1k tube preamps and have not been impressed.

Yup, this is also why I recommended looking into how much gain you NEED. If you don't need the gain, why spend the money on a voltage amplifier? A good preamp, meaning one that won't sound worse than the amp by itsself will cost a lot of money.

You should ask Moscode what the input sensitivity of your amplifier is. If it takes under 2V RMS to reach full power, then I'd recommend looking for a passive preamp, which BTW isn't going to be cheap either, but at least with a passive you can afford a good volume control and switches, which are a lot of the cost of a good active preamp anyway.  

I spent about $1k just in parts to build my preamp... there's no way you're going to get a complete unit for $1k-ish that's not going to suck unless you find a used deal somewhere.

[StereoNut]

Rich, Rollo & Dave

Thanks for your collective posts.  It's great to have a wealth of knowledge "on tap" here (Pete's ears just perked up!  "Tap, what's on tap... where? ) at AN.  I will ask George Kaye the specs on the 600 in relation to matching pre-amps to it and continue to read and learn from all of you.  That's what makes having a forum like this soooooo valuable.

Kudos to everyone who has contributed to this topic.  It is a big help to me.  Keep those "cards and letters" comin'!

Bill