For me the "Classic" Hybrid amp is that amp who the gain stage or the gain stages are constructed only with tubes and the output stage ( the current stage ) is SS , tubes as is well known ( and as many others mentioned before me ) has the advantage that their sound is rich in even order harmonics , I call it advantage because this give you the chance " to cut and sew " till you optain the sound that you want by playing with the tube schematic , differential , LTP or single ended .... degenerative , local or overall feedback , many ways to reduce or to increase the amount of the even order harmonics that you want .
I've designed some tube preamp class D power amps, everytime with good results.
From clean guitar/bass amps (also with mosfet cathode followers), to multichannel guitar amps, to something more audiophilish.
I would not focus on even order harmonics only, as a good sounding amp has, at least to my ears, a good balance of even and odd harmonics.
From clean guitar/bass amps (also with mosfet cathode followers), to multichannel guitar amps, to something more audiophilish.
I would not focus on even order harmonics only, as a good sounding amp has, at least to my ears, a good balance of even and odd harmonics.
this part "THD was under 0.005%, and was mostly second harmonic" i found quite remarkable.
as an aside, it was fun to be taken back in time by the article's mention of 2E26 -- wow, haven't touched one of those since my tube RF (Class C anode A.M.) days, decades ago.
Moskido
I built a Moskido amp a couple of years ago and since have been upgrading it. It is clearly the best sounding amp I have ever built or bought. It bested an Atma-Sphere M60 I used to own.
For years I thought that the holy grail of amps was parafeed SE amps so I built one with 2A3s and another with 12B4 output tubes.
These sound very nice, but the Moskido has it all - detail, musicality, dynamics, soundstage, effortless flow. With the right recordings the musicians step out of the speakers into the room. At times you can hear the size and shape of the musical instruments. Vocals are so real - zero sibilance.
The diyAudio thread for this was erased for reasons I don't know, but you can see the circuits on the Mad Scientist Audio web site. My Aikido stage uses 6SN7 in the gain stage and 6BX7 in the driver stage configured for push-pull. The output stage uses BUZ900/905 mosfets. I built my own bias and servo feedback boards. Not a project for beginners, but for me, no need to try anything else.
I built a Moskido amp a couple of years ago and since have been upgrading it. It is clearly the best sounding amp I have ever built or bought. It bested an Atma-Sphere M60 I used to own.
For years I thought that the holy grail of amps was parafeed SE amps so I built one with 2A3s and another with 12B4 output tubes.
These sound very nice, but the Moskido has it all - detail, musicality, dynamics, soundstage, effortless flow. With the right recordings the musicians step out of the speakers into the room. At times you can hear the size and shape of the musical instruments. Vocals are so real - zero sibilance.
The diyAudio thread for this was erased for reasons I don't know, but you can see the circuits on the Mad Scientist Audio web site. My Aikido stage uses 6SN7 in the gain stage and 6BX7 in the driver stage configured for push-pull. The output stage uses BUZ900/905 mosfets. I built my own bias and servo feedback boards. Not a project for beginners, but for me, no need to try anything else.
6A3 A2
Bigun, I built the ElectraPrint 6A3 A2 PP monoblock design a few years ago. You may recall commenting on the pics. The design isn't on the ElectraPrint site now days, but will show up on a search.
The design uses a TDA2030 at the front end and an interstage trafo. Got a lot of guff about the chip. The amps sound great to me. The very bottom end doesn't have as much control as I would like. I run with an OPPO 105 and open baffles. Regards, Bill
Bigun, I built the ElectraPrint 6A3 A2 PP monoblock design a few years ago. You may recall commenting on the pics. The design isn't on the ElectraPrint site now days, but will show up on a search.
The design uses a TDA2030 at the front end and an interstage trafo. Got a lot of guff about the chip. The amps sound great to me. The very bottom end doesn't have as much control as I would like. I run with an OPPO 105 and open baffles. Regards, Bill
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Joined 2009
Paid Member
Thanks for the updated input guys. I'm still doodling some hybrid designs of my own (quite likely not original though) and have been encouraged by much of the input in this thread.
keep it coming !
keep it coming !
i've included a relatively vanilla balanced input hybrid option here:
http://www.diyaudio.com/forums/chip...ing-t-network-fb-point-point.html#post4103749
it's at the bottom of the schematic. you can go directly to the schematic here:
https://drive.google.com/file/d/0Bz_iSmmoJEGTemRQV3B0U1haQzQ/view
the hybrid is the schematic the bottom of the page
http://www.diyaudio.com/forums/chip...ing-t-network-fb-point-point.html#post4103749
it's at the bottom of the schematic. you can go directly to the schematic here:
https://drive.google.com/file/d/0Bz_iSmmoJEGTemRQV3B0U1haQzQ/view
the hybrid is the schematic the bottom of the page
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+1
The bipolar DC servo version really rocks. I am running 6sl7/6sn7 aikido to the buz MOSFET stage. I think I am running the MOSFET stage at about +/- 60v. Bias is achieved via the Pass burning amp bias boards. Running about 1.8A per device in a 3U modushop case with heatsinks and it gets pretty hot. One of my favorite power amps so far.
I built two choke loaded hybrid single ended 10W power amps, both source followers.
One with an ECL84 mu stage driving the Sony Vfets and the other one I used Sy's His Masters Noise output section ,driving the SemiSouth power Jfets. Very simple ,not enough gain for NFB, consuming less than 100W. Both sounds very nice.
I using them with powered subs.
One with an ECL84 mu stage driving the Sony Vfets and the other one I used Sy's His Masters Noise output section ,driving the SemiSouth power Jfets. Very simple ,not enough gain for NFB, consuming less than 100W. Both sounds very nice.
I using them with powered subs.
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Gary Pimm (formerly of Tektronix) built a stereo poweramp that has what looks like the front end of a Dynaco ST70, but with a pushpull MOSFET output section in place of the EL34's. I saw the schemo about a decade ago, but it doesn't seem to be on his website. I remember him saying that it dissipated a lot of power at quiescence (The FETS). It sounded top notch to me, but everything else in the system was also top notch. Hard for me to judge if it was better sounding than any other poweramp. I'd bet it would compete well with anything though. Gary is a very sharp audio engineer.
I saw Gary a few months ago at Bud Purvine's house. It was my understanding that he was back at Tektronics and working for them just a week or so ago when I received an E-mail from him...
However, you're certainly correct, Gary is a very sharp guy!
Best Regards,
TerryO
Did you use the pentode section as triode strapped cathode follower going to the sony vfets...would you mind sharing the schema?
Thanks
I twisted everything around and used a PN4393 jfet differential stage cascoded with the small triodes from a pair of 6CS7 dual dissimilar triodes. This drove a pair of source followers ginned up from the big triodes of the 6CS7s, which drove 7591As into output XFMRs from a Fisher 500B receiver.
The results are tabulated n the "Kingfisher" thread in the tubes section.
The results are tabulated n the "Kingfisher" thread in the tubes section.
I have got some very favorable comments using an Alembic F2B into the effects return loop on a few sand amps around here.
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Joined 2009
Paid Member
I just realize this is an old thread...I'm just going to share a little.
My current setup is hybrid. 12ax7 (Chinese tube, 9th gen) DC couple cathod follower preamp with WIMA MKP10 output cap to a TPA3116D2 modded YJ blue board (as in the class-d forum). I also use an LM723 analogue power supply for the YJ board. I really like the sound both at high and low volume. This is by far the most satisfied build I have ever made.
I don't have an all tube amp to compare yet. I always to have an all tube amp. Been thinking about getting Edcor OPT to build one.
Next when the weather gets cooler, I will pull out the JLH as power amp and see what kind of sound I'm getting from this combination.
My current setup is hybrid. 12ax7 (Chinese tube, 9th gen) DC couple cathod follower preamp with WIMA MKP10 output cap to a TPA3116D2 modded YJ blue board (as in the class-d forum). I also use an LM723 analogue power supply for the YJ board. I really like the sound both at high and low volume. This is by far the most satisfied build I have ever made.
I don't have an all tube amp to compare yet. I always to have an all tube amp. Been thinking about getting Edcor OPT to build one.
Next when the weather gets cooler, I will pull out the JLH as power amp and see what kind of sound I'm getting from this combination.
I built this http://home.kpn.nl/verwa255/esl/amp.zip hybrid amplifier in 2003 to directly drive a DIY electrostatic loudspeaker built by my (then) colleague Frank Verwaal. The amplifier was by far the most dangerous DIY circuit I ever made.
It sounded very beautiful and neutral, but also too soft. 2 kV peak output voltage simply wasn't enough. If I were to do it again, I would probably go for a custom wound supply transformer, like Lampie519 uses, and SRPP output stages. That brings some extra complications because the upper valves require their own heater transformers which load the output with their capacitance between the primary and secondary windings, but at least that could solve the hopeless inefficiency of the circuit.
It sounded very beautiful and neutral, but also too soft. 2 kV peak output voltage simply wasn't enough. If I were to do it again, I would probably go for a custom wound supply transformer, like Lampie519 uses, and SRPP output stages. That brings some extra complications because the upper valves require their own heater transformers which load the output with their capacitance between the primary and secondary windings, but at least that could solve the hopeless inefficiency of the circuit.