I have one of these on my shelf.
::: Aspen Amplifiers :::
Not using it since I went to tube power amps but it did what you are asking for when I was running SS power amps.
A bit pricey though.
It uses relay source selection, then SS buffer ahead of the volume pot, and then a tube output stage.
Without giving away too much of Hugh's IP, each channel runs a ECC189 triode as a cathode follower at about 10mA idle. The second half of the the twin triode runs as a cathode follower "drone" with an inverted input signal, as a result there is zero net signal current from the high voltage (approx +140V) power rail.
Note the ECC189 (6ES8) is a VARIABLE Mu tube (variable mu version of ECC88/6DJ8).
Cheers,
Ian
::: Aspen Amplifiers :::
Not using it since I went to tube power amps but it did what you are asking for when I was running SS power amps.
A bit pricey though.
It uses relay source selection, then SS buffer ahead of the volume pot, and then a tube output stage.
Without giving away too much of Hugh's IP, each channel runs a ECC189 triode as a cathode follower at about 10mA idle. The second half of the the twin triode runs as a cathode follower "drone" with an inverted input signal, as a result there is zero net signal current from the high voltage (approx +140V) power rail.
Note the ECC189 (6ES8) is a VARIABLE Mu tube (variable mu version of ECC88/6DJ8).
Cheers,
Ian
"Tubey overdrive" is not the same as "Tubey sound". You can add specific tube saturation, but you can never add absence of specific to typical solid state amps dynamic distortions.
I can add such "tube sound" without tubes, just 3 solid state diodes in feedback lop of an opamp. It is easy. But nobody can add transparency of decaying sounds and reverberation, when you hear the wind in the church where it was recorded.
The "Foreplay" does sound good, but it introduces what can easily be excessive voltage gain. IME, the "Foreplay" works well in combination with low gain phono preamps, including the inexpensive, battery powered, "Little Rat" bought from Radio Shack.
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I take it that this is implied when folk familiar with SS amps proceed to ask for advice on how to obtain tighter stronger bass from their tubes.
As the o p you should know there is only one reason I do not have tube amps. I do not have room in my setup at all. If I could get a great sounding powerful tube amp that was only 3 in wide, and maybe 15 inches long, and was balanced monoblocks for about $800 for the tip. And that's for both of them. Then I would own tube amplifiers.
Space and $ work against you. Acquire a nice tube DAC and pair it with the 12B4 line stage. To get even more "tube flavor", acquire a turntable and tubed phono preamp.
Many a good sounding system employs tube equipment in the small signal roles and SS equipment for power amplification.
I built an Elekit TU-8600S 300B last Christmas. It clearly sounds different from all my other amps. It has a kind of clarity, detail, and holographic-ness (whatever the right word is) that is very unique. I also measured the harmonic distortion profile, and was surprised by how high the distortions are but yet it sounds so nice and "clean" (in fact very clean).
Then I came across to this PKHarmonic plugin. I entered the harmonic profile from my measurement, and played some music on my cheap $60 class D Chinese desktop amp with cheap Onkyo speakers taken from my old surround sound system. I was really surprised by how similar it sounds compared to my system with 300B amp. It doesn't have the same FR, imaging...etc. but it does have the same quality of clarity, detail...etc. that I cannot quite describe. There is a bypass button that I could do A/B comparisons, and the difference was real.
I'm now pretty convinced that there is no magic in tubes. It is just the harmonic profile at play. Good sound (and "clean sound") does not need low distortions.
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>>no magic in tubes. It is just the harmonic profile at play
Exactly. I've realized that I prefer my music playback with a fair amount of 2nd order distortion, but without any limiting or bass compression. A little bit of enhanced spatialization from "room effect" modeling is nice too. It's enlightening to see exactly what effects in our reproduction chains are giving our brains the pleasure from music that we all seek. And it's great to not have to constantly replace hardware to do it.
Exactly. I've realized that I prefer my music playback with a fair amount of 2nd order distortion, but without any limiting or bass compression. A little bit of enhanced spatialization from "room effect" modeling is nice too. It's enlightening to see exactly what effects in our reproduction chains are giving our brains the pleasure from music that we all seek. And it's great to not have to constantly replace hardware to do it.
>>We also have different preferences when it comes to the distortion we call music. It would be interesting to have a knob that goes both ways. Could you remove the tube sound from audio recorded in the days >>when vacuum tubes were dominant? Would it sound "better" to everyone?
I doubt it. I think part of the "magic of tubes" is that their euphonic distortions might sound good in themselves, but are also masking other objectionable distortions that exist at every point in the signal chain. Adding tube sauce to a modern high-fidelity recording might make it sound "better," but having it baked into a mediocre recording made with 70 year-old equipment and techniques may just be what is making it listenable at all.
Not to say that analog equipment hasn't been refined to a very high level of performance, it certainly has. But it took at least a few decades for that to happen, and to get recordings on the level of, say, Dark Side of the Moon. And you could say the same for solid state or digital, too.
I doubt it. I think part of the "magic of tubes" is that their euphonic distortions might sound good in themselves, but are also masking other objectionable distortions that exist at every point in the signal chain. Adding tube sauce to a modern high-fidelity recording might make it sound "better," but having it baked into a mediocre recording made with 70 year-old equipment and techniques may just be what is making it listenable at all.
Not to say that analog equipment hasn't been refined to a very high level of performance, it certainly has. But it took at least a few decades for that to happen, and to get recordings on the level of, say, Dark Side of the Moon. And you could say the same for solid state or digital, too.
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The problem is, you can't have harmonic distortion without intermodulation distortion, which isn't pleasing.
Personnally I never owned any vinyl but started in the sixties with tape recorders. Over a long weekend I recorded about 15 LP at friends, things like Mahavishnu Orchestra, Billy Cobham etc., it was the age of jazz rock. For the next time this was my music pool I listened to day and night. Many weeks later I visited the same friends again, listened to their TT and found the sound boring being mine superior.
Searching the reason for that mystic sound improvement I inspected my tape recorder Revox A77 and discovered a wiring error in my setup that mixed some playback output back to the input during recording - resulting in some fast decaying echos! Meanwhiule I had got totally accustomed to that sound and so the original without these echos was inferior to me.
This is one of my personal experiences that lets my laugh at all these subjective sound debates
Searching the reason for that mystic sound improvement I inspected my tape recorder Revox A77 and discovered a wiring error in my setup that mixed some playback output back to the input during recording - resulting in some fast decaying echos! Meanwhiule I had got totally accustomed to that sound and so the original without these echos was inferior to me.
This is one of my personal experiences that lets my laugh at all these subjective sound debates
So, referring to post # 109 the recipe is to add 1% 2nd harmonic, 0.3% 3rd harmonic and you get tube sound.
The main question is, the dependence of the level of such harmonics on the signal level.