share your experience on sound of hybrid amps

[Bigun]

I've seen some interesting hybrid amps about but very little information on how they sound. I'd like to get a bit of a feel for how different approaches to hybrid amps have on the sound.

By hybrid I don't mean some sand somewhere in amongst the glass (such as a CCS plate load) - but something more substantial such as SS gain stage feeding tube output via OPT, or tube gain stage feeding SS output buffer.

Thanks.

 

[nigelwright7557]

I designed a hybrid with SRPP valve front end and SS back end.
Just sounded like a SS amplifier.

To get the full valve sound you need front end, splitter and output stage then output transformer. All add to the sound.

 

[Bigun]

A simple design from Croft uses a 12AX7 to drive a pair of LATFETs. Open loop. Simple. Should be terrible.

But: Croft Acoustics Phono Integrated integrated amplifier Stephen Mejias comments | Stereophile.com

 

[M Gregg]

To try it,

connect a valve pre to a SS amp, it can sound quite good..
I think the best way is tube pre with SS power.

I have used this quite a few times. Even a valve preamp with SS chip amp sounds quite good!

I have never tried using FETS to drive an output transformer with a valve pre.

I would not use a valve driver stage with SS listened to one and didn't like it.. perhaps it wasn't well designed but it had all the bad side of both SS and tube.

I would keep the tube stage as a line stage and either drive a chip amp or full SS output stage..as with everything YMMV..

If you think about it its not much different to a CD player with tube output driver driving a SS power amp.

It can sound better than a mediocre tube power amp stage and it's cheaper....Bass can be quite good! (no output Tx)

Aside from the HIFI Marshall used a tube stage in the pre and SS output for the overdrive stage on a few amps..I think it was called valvestate.
However the OD is not the same as flat out power overdrive... with volume control with a power brake.

Regards
M. Gregg

 

[M Gregg]

A few years back,

I made a valve preamp, it had 3 guitar channels a marshall, a fender, and a Messa boogie that was switchable/ selectable from a foot switch/front panel switch and fed it into a standard separate tube power amp section with the other channel being HIFI..it was good fun, however I gave it away..(as you do)..

Then regretted it..

It happened after I put switches on my hifi amp for Triode pentode UL..and couldn't make my mind up which guitar amp I liked. So I built the pre with the intention of making a decision and then building a full blown amp..

The only problem was after I built it I liked all the sounds and couldn't give them up.. ..it was one of those mad ideas..Oh it had a valve vibrato section as well..Think I'd have had better things to do..I used to plug that into SS and tube heads.

Regards
M. Gregg

 

[Bigun]

Even a valve preamp with SS chip amp sounds quite good!

Interesting idea, looksy what I found: JLTi MK2

 

[M Gregg]

An Aikido line stage feeding a chip amp can sound good as well!
I tried it with ECC88's.
Of course its lower mains power and less heat.
It will be interesting to see what you do!

I have known people try building a good low power tube amp and use it as a pre to drive a SS power stage..However I have never listened to one.
I would think it would be high distortion but perhaps that's just the way it sounds..I think the idea was to drive some kind of interstage transformer as the OP Tx with power tubes.
Anyway catch you laters..

Regards
M. Gregg

 

[a.wayne]

I do second tooob pre with SS AMPLIFICATION , there is no valve sound with right toobs , like when using toob amplfier , the combinatition with a good pre is just good sonics top to bottom, tooob rolling is highly recommended....

 

[pmillett]

I've designed a few, headphone amps and <20W power amps. My strategy has always been to use a SE tube stage to do the voltage amplification, and the SS stage as a unity gain current amp.

You can make such an amp sound like pretty much anything you want. I've always set up the tube stage to have a modicum of 2nd order distortion - on the order of 0.1-0.2% at 1 watt (power amp) or 1V (headphone amp). The low order harmonics in theory will mask anything that the output stage will create, as long as you have enough headroom to stay well away from clipping.

I built two amps that very closely mimicked a 300B SE amp, both in measurements and listening tests...

Pete

 

[M Gregg]

I built two amps that very closely mimicked a 300B SE amp, both in measurements and listening tests...

Pete

Schematic? Just curious..


Regards
M. Gregg

 

[freddi]

love to see a schematic too - can a certain amount of the emulation be done with a standalone preamp circuit and a common solid state amp?

 

[Bigun]

I think a tube pre-amp and SS power amp is not what I'd call a hybrid, maybe putting them in the same box makes it an integrated amp. So a front end and then a SS output where the SS output has its own complete nfb loop is not really what I meant when I asked for opinions about hybrids - BUT if it is the best way of combining tubes and SS then that is something useful to recognize ?

 

[MrCurwen]

What is the definition of 'hybrid'? I've seen many call designs that have source followers or MOSFET CCSs hybrids.

I tend to think that a hybrid design would be one that has a solid state voltage gain device in it. Thoughts?

 

[Koifarm]

I do not know if this is hybrid enough.

The tube replaces the input opamp from the class D board.

ECC99 srpp pre with Class D 400Watt end.

 

[Koifarm]

Another picture.

The tube makes the class D amp just sound right for me.

Without the tube, this class D amp sounds to sharp for me. With the tube it sounds rounder at the hights.

 

[Koifarm]

Another picture.

 

[Bigun]

Interesting Koifarm, do you have a thread on this with more details ?

 

[Koifarm]

Schematic of the tube part. After that use Hypex UCD with the input opamp bypassed.

 

[Koifarm]

The thread of the build is only in Dutch.
forum.zelfbouwaudio.nl • Toon onderwerp - Retro moderne versterker

 

[famousmockingbird]

Schematic? Just curious..

I think Pete did better than just a schematic



Glowing Hybrid Amp