Matching Solid State Amp w/ Tube Preamp

[DancingSea]

Aloha,

 

Are there impedance or other technical issues to such a pairing?  Or can one freely mix solid state amps w/ tube preamps?

 

Thanks

[mourip]

I think that it ends up being trial and error however I have always found it to be a good combination. I am careful to turn on the preamp first and then wait a minute before turning on the amp and also turn the preamp off last. Some tube preamps can put out some nasty stuff while warming up. I know this for a fact as I once fried the woofers in my speakers by forgetting. Newer and better preamps often have a relay on a timer for their outputs to avoid this

[esldude]

Not quite trial and error. 

 

Some tube preamps have high output impedances.  Some solid state amps have lower input impedances.  You don't want a tube preamp with 1 k ohm output impedance feeding a solid state amp with a 10 k ohm input impedance.  Well it might barely be okay.  A tube preamp with 1 k ohm output impedance feeding a solid state amp with 47 k ohm input impedance should be just fine. 

 

Related tube pre-amps may typically use an output capacitor to couple to the amplifier.  Again keep plenty of impedance in the solid state amp so this doesn't cause a roll off in the bass. 

 

One final area that used to be a problem.  Tube preamps might be asked to deliver 2 volts or so yet be able to output 20 volts or more.  This can lead to running the tube pre-amp at a very low volume setting if it has more gain than is needed.  This doesn't get the best sound from the tube circuit in some designs. 

 

So use a solid state amp with 47 k ohm or higher input impedance.  Use a tube pre with a lower output impedance (not hard to find one with only 300 ohms), and don't get a tube preamp with lots more gain than you need for the power amp.  I would suggest not going over a preamp gain of 12 db in general.  

[GUTB]

There's a couple of factors. There's the common wisdom of pairing preamp output impedance at least 1/10 of the input inedence of the amp -- this shouldn't be a problem most of the time. You don't want the preamp bottlenecking the amp so make sure output topology matches and bandwidth is close. If you are using monoblocks the pre should be true balanced topology (dual mono most of the time) -- the signal is not summed or combined in any manner. If your amp goes out to 150 KHz the pre should go out to at least that much.

 

Now you may ignore some matching for the sake of outright quality gains from super high performance preamps like an Audio Note for example -- the net SQ gain is better than a lesser but balanced pre unit.

[DancingSea]

What part do tube buffers play in this?

[Allan F]

1 hour ago, mourip said:

I think that it ends up being trial and error however I have always found it to be a good combination. I am careful to turn on the preamp first and then wait a minute before turning on the amp and also turn the preamp off last. Some tube preamps can put out some nasty stuff while warming up. I know this for a fact as I once fried the woofers in my speakers by forgetting. Newer and better preamps often have a relay on a timer for their outputs to avoid this

 

It is generally recommended that you turn on an amp last for the reason you state but, for that same reason, it is also recommended that you turn it off first, i.e. before turning off the preamp. IOW, the turn off sequence should be the reverse of the turn on sequence.

[esldude]

1 hour ago, DancingSea said:

What part do tube buffers play in this?

 

Well a tube buffer would have no gain.  Provide some high input impedance and low output impedance.  Might impart a bit of the tube sound.  Though often if well designed they sound about the same as solid state device.  Though if you are wishing for the tube sound maybe that isn't well designed for the purpose.  

 

BTW, it is often assumed tube amps have a good musical sound, and tube preamps in front of solid state amps are a way to get some of this flavoring.  Usually doesn't work out that well.  I prefer the color of tube amps myself (specifically triodes).  Pre-amp circuits are different however in that they don't have transformers, and handle the loads they are connected to so well that some of the more musical aspects of a tube amp never come into play.  Other than using tubes they aren't really the same effect as push pull amps running thru transformers. 

[sandyk]

25 minutes ago, esldude said:

Well a tube buffer would have no gain.  Provide some high input impedance and low output impedance.  Might impart a bit of the tube sound.  Though often if well designed they sound about the same as solid state device.  Though if you are wishing for the tube sound maybe that isn't well designed for the purpose.  

 

 

 I have previously seen numerous member reviews in another mainly Tube type forum ( Musical Fidelity mainly) where the tube buffers were specifically used to impart a tube flavour,  and all of them did to some degree.

Why anyone would use a well designed neutral sounding vacuum tube buffer, with it's higher running costs, warm up delays etc. over a similar performing Solid State Buffer beats me !

If a buffer is used in conjunction with a vacuum tube output stage based DAC, surely a neutral sounding solid state buffer would make more sense, due to it's normally lower output impedance, and ability to correctly drive all types of power amplifiers ?

[mourip]

1 hour ago, Allan F said:

 

It is generally recommended that you turn on an amp last for the reason you state but, for that same reason, it is also recommended that you turn it off first, i.e. before turning off the preamp. IOW, the turn off sequence should be the reverse of the turn on sequence.

 

Yes. I said " and also turn the preamp off last."

 

The reverse would be to turn off the amp first and the preamp last. Sorry if that was not clear enough.

[Allan F]

3 minutes ago, mourip said:

 

The reverse would be to turn off the amp first and the preamp last. Sorry if that did not come across.

 

No. if you turn on the amp last in the turn on sequence, the reverse of that would be to turn it off first in the turn off sequence.

[mourip]

2 hours ago, DancingSea said:

What part do tube buffers play in this?

 

Tube buffers can help with impedance matching without giving too much gain.

 

Some also like the tube "flavor" that is imparted. The flavor part is a matter of personal preference.

[mourip]

11 minutes ago, Allan F said:

 

No. if you turn on the amp last in the turn on sequence, the reverse of that would be to turn it off first in the turn off sequence.

 

That is what I said...

 

Here is a quote from a good company that manufactures David Berning circuits. This would apply to tube preamps without muting circuits.

 

 "...you must turn on the MicroZOTL2 before you turn on your power amp, and turn your power amp off before you turn off the MicroZOTL2. The MicroZOTL2 should therefore be the first thing on and the last thing off."

[Allan F]

12 minutes ago, mourip said:

 

That is what I said...

 

Sorry, my bad. That is what you said. I misread your post and reacted too quickly.

[mourip]

No problem. I do that all the time!

[esldude]

8 minutes ago, mourip said:

 

That is what I said...

 

Here is a quote from a good company that manufactures David Berning circuits. This would apply to tube preamps without muting circuits.

 

 "...you must turn on the MicroZOTL2 before you turn on your power amp, and turn your power amp off before you turn off the MicroZOTL2. The MicroZOTL2 should therefore be the first thing on and the last thing off."

Have not tried the Micro line of products.  But the original Berning preamp was really something.  More than 200 khz bandwith flat.  Used FETs with Tubes. 

 

I seem to recall the amps were something like modern switching amps.  Can't remember if the preamp worked the same way or not (I don't think it did).  

[Mshenay]

Great thread, I'm quite liking it my self though... I always thought it was common knowledge to turn your pre on first and off last? I just remember my step father always doing that back in the day with his old stero 

 

No idea what components he used but it was always the first on is the last off, and everything went on or off in that order... 

[TubeLover]

5 hours ago, esldude said:

Have not tried the Micro line of products.  But the original Berning preamp was really something.  More than 200 khz bandwith flat.  Used FETs with Tubes. 

 

I seem to recall the amps were something like modern switching amps.  Can't remember if the preamp worked the same way or not (I don't think it did).  

The Micro ZOTL MZ2s preamp is an absolute steal. Numerous reviews have shown it besting high end preamps running 10-20 times it's cost. I own one, as do a number of other extremely happy CA members. Might be the single greatest value in high end audio performance.

 

They also come with a free home audition period. 

 

JC

[mourip]

7 hours ago, TubeLover said:

The Micro ZOTL MZ2s preamp is an absolute steal. Numerous reviews have shown it besting high end preamps running 10-20 times it's cost. I own one, as do a number of other extremely happy CA members. Might be the single greatest value in high end audio performance.

 

They also come with a free home audition period. 

 

JC

 

+1. I have been using the Linear Tube Audio MZ2+ with upgraded LPS for a while. It is a great value and for me a winner on an absolute level. Adding NOS tubes brings it up even farther.

 

I am now using LTA's new "Ultralinear" amp. 20 watts from 17JN6 Compactron output tubes. It is basically David Berning's ZH-230 with output tubes that have a different heater voltage and costs way less. This bests my previous Pass Labs SIT2 by quite a bit.

 

Sorry to digress...

[DancingSea]

13 hours ago, TubeLover said:

The Micro ZOTL MZ2s preamp is an absolute steal. Numerous reviews have shown it besting high end preamps running 10-20 times it's cost. I own one, as do a number of other extremely happy CA members. Might be the single greatest value in high end audio performance.

 

They also come with a free home audition period. 

 

JC

 

Is the Micro ZOTL MZ2 used as an actual preamp for a full system, speakers, etc?  Or is it just a headphone amp?

 

Also, is the $700 LPS required to use it?  

 

Thanks.

[firedog]

2 hours ago, DancingSea said:

 

Is the Micro ZOTL MZ2 used as an actual preamp for a full system, speakers, etc?  Or is it just a headphone amp?

 

Also, is the $700 LPS required to use it?  

 

Thanks.

It can be used as a line preamp for a full system. Reviews say it is great in that role. On the web site, it can be ordered with a less expensive PS that doesn't add big bucks to the price. 

[DancingSea]

7 minutes ago, firedog said:

It can be used as a line preamp for a full system. Reviews say it is great in that role. On the web site, it can be ordered with a less expensive PS that doesn't add big bucks to the price. 

 

A friend, and fellow CA member, insists its only for headphone use.  That the speakers used in the Stereophile review are ZuAudio Soul Supremes that are so efficient that they use headphone like power.

 

Will the MZ2 work with regular towers, or only with those of the ZuAudio's ilk?

 

Thanks.

[Chris_B]

49 minutes ago, DancingSea said:

 

A friend, and fellow CA member, insists its only for headphone use.  That the speakers used in the Stereophile review are ZuAudio Soul Supremes that are so efficient that they use headphone like power.

 

Will the MZ2 work with regular towers, or only with those of the ZuAudio's ilk?

 

Thanks.

I use it as a preamp in my 2-channel stereo hooked into 2 solid state mono block amps.  It has a low output impedance so it should match well driving most solid state amps.  Now if you want to use it as an integrated preamp/amp, it does have speaker terminals on the back but they would have to very efficient speakers since it only puts out 1 watt into a 4-ohm load.

 

It is a pretty tremendous preamp and I'm guessing headphone amp.  Very neutral and resolving.  

[DancingSea]

30 minutes ago, Chris_B said:

I use it as a preamp in my 2-channel stereo hooked into 2 solid state mono block amps.  It has a low output impedance so it should match well driving most solid state amps.  Now if you want to use it as an integrated preamp/amp, it does have speaker terminals on the back but they would have to very efficient speakers since it only puts out 1 watt into a 4-ohm load.

 

It is a pretty tremendous preamp and I'm guessing headphone amp.  Very neutral and resolving.  

 

Thanks.  What speakers are you using?

 

Also, does the MZ2 impart a nice tube type sound?

[TubeLover]

Forget anything related to it being a headphone amp (it can do that and well) but it's primary purpose is as an ultra high end preamp at a give away price. It's stunningly good, in my system and many others. Read these reviews by noted reviewers:

 

https://hometheaterreview.com/linear-tube-audio-microzotl20-preamplifierheadphone-amplifier-reviewed/

 

https://parttimeaudiophile.com/2017/02/26/review-linear-tube-audio-microzotl2-0/

 

http://www.theabsolutesound.com/articles/david-berning-microzotl20-personal-amplifier/

 

JC

 

 

 

 

[TubeLover]

6 hours ago, DancingSea said:

 

Thanks.  What speakers are you using?

 

Also, does the MZ2 impart a nice tube type sound?

With good NOS tubes it's brilliant!

 

JC