A tube buffer that gives tube sound.

[BarrryBarrry]

Hi people!
I'm getting slowly my way in audioland. Had some upgrades an finally got that sound I like (for now). Setup is a Tv, optical, Nuprime dac-9, Nuprime AMG STA, RU connected copper cables, B&W 683 S2, old Rel quake sub and a big diy acoustic panel on the sealing.
I would like to experiment with the sound and I'm interested in adding a tube buffer in de system. I read that it can compliment a class D amp. There are some chifi cheap options that you can add between the dac and amp. My question is, how could I get a tube buffer that makes a big (as possible) difference to the sound and I can put on and off easy and preferable I would like to be able to have some tone control.
What I would prefer to achieve les harsh sound, warmer voices and air. Budget under €200,-
Thank you

 

[Saponetto]

Hi and welcome.
Hmmm... before starting to compile the rigs list, better to have well clear what are your effective requirements.
As far as I can understand, a good approach could be a Schiit Freya, in order to be able to experiment a lot and get a better focus.

 

[BarrryBarrry]

Hi and welcome.
Hmmm... before starting to compile the rigs list, better to have well clear what are your effective requirements.
As far as I can understand, a good approach could be a Schiit Freya, in order to be able to experiment a lot and get a better focus.

The Shiit Freya is not available in The Netherlands and I forget to add my budget, under €200.

 

[DVDdoug]

There is no "one tube sound". A tube can simply amplify cleanly and sound just like any good solid state amp, or it can distort. If it distorts it will be different from another tube amp.

You'd have to listen to see if you like the distortion from a particular amp.

A buffer isn't supposed to sound like anything... Normally a buffer has high input impedance and low output impedance with no gain (a gain of 1.0) but tubes are not the best thing for low output impedance. A tube buffer or preamp is less likely to have a "sound" than a tube power amp, which has an output transformer that can also (sometimes) distort the sound.

Tubes tend to soft-clip when overdriven, but it depends on the circuit design. Guitar players usually like tube amps because of the way they distort when driven hard, but again, they usually have their favorite amp to go with their favorite guitar because they all sound different.

I read that it can compliment a class D amp.

A hi-fi amplifier (unlike a guitar amp & cabinet) isn't supposed to have any sound of its own, no matter the "class".

 

[Digby]

Have you tried EQ and/or room correction? That would probably be a better place to start, before trying tubes.

 

[Blumlein 88]

Welcome to ASR.

Most tube sound such as there is comes from tube amps. Tube pre's, DACs whatever can be pretty clean. Lots of those things you read like tube DACs compliment class D are more wishful thinking and bias than anything.

Your speakers have an up and down impedance curve. You could put a .5 ohm power resistor in series with the speaker at your amp output and get frequency response modification like a tube amp often creates.

Not trying to rain on your parade or anything, but lots of this audio wisdom is just old wive's tales.

 

[kemmler3D]

Welcome to ASR!

You may not like this suggestion, but if you want to experiment with tube sound on a budget, quickly and easily?

Software is the answer.

Get one of these (or anything similar): https://www.amazon.com/Lenovo-ThinkCentre-Desktop-i5-6500T-Windows/dp/B07QGLC4FW/

Get one of these: https://www.amazon.com/LEAGY-External-Sound-Card-8-Channel/dp/B07VSHCGWD/

Use EQAPO

And use some of these: https://www.kvraudio.com/plugins/distortion-saturation-plugins ... this developer has some really high quality, fairly subtle distortion plugins for free: https://varietyofsound.wordpress.com/ ... there are hundreds of options out there, many cost nothing.

From there you can find out what kind of distortion profile sounds best to you, and then perhaps buy a hardware unit that does similar things. Or just stick with DSP.

 

[BarrryBarrry]

Have you tried EQ and/or room correction? That would probably be a better place to start, before trying tubes.

I did some correction with acoustic panels because the acoustic was very bad. It made a big difference but I never measured anything. I think good measurement or eq is going to exceed the budget for this moment.

 

[BarrryBarrry]

Welcome to ASR.

Most tube sound such as there is comes from tube amps. Tube pre's, DACs whatever can be pretty clean. Lots of those things you read like tube DACs compliment class D are more wishful thinking and bias than anything.

Your speakers have an up and down impedance curve. You could put a .5 ohm power resistor in series with the speaker at your amp output and get frequency response modification like a tube amp often creates.

Not trying to rain on your parade or anything, but lots of this audio wisdom is just old wive's tales.

Interesting, I'll Google the transistor option.

 

[BarrryBarrry]

Welcome to ASR!

You may not like this suggestion, but if you want to experiment with tube sound on a budget, quickly and easily?

Software is the answer.

Get one of these (or anything similar): https://www.amazon.com/Lenovo-ThinkCentre-Desktop-i5-6500T-Windows/dp/B07QGLC4FW/

Get one of these: https://www.amazon.com/LEAGY-External-Sound-Card-8-Channel/dp/B07VSHCGWD/

Use EQAPO

And use some of these: https://www.kvraudio.com/plugins/distortion-saturation-plugins ... this developer has some really high quality, fairly subtle distortion plugins for free: https://varietyofsound.wordpress.com/ ... there are hundreds of options out there, many cost nothing.

From there you can find out what kind of distortion profile sounds best to you, and then perhaps buy a hardware unit that does similar things. Or just stick with DSP.

Sounds like a great option en much cheaper then mini DSP. I'm probably to noob to invest in this option, I'm afraid I'll don't get this working.

 

[kemmler3D]

Sounds like a great option en much cheaper then mini DSP. I'm probably to noob to invest in this option, I'm afraid I'll don't get this working.

Cool, good luck! I just randomly noticed yet another free tube emulation software: https://www.soundonsound.com/news/fuse-audio-labs-vpre-72

 

[djwalter2000]

Welcome to ASR!

You may not like this suggestion, but if you want to experiment with tube sound on a budget, quickly and easily?

Software is the answer.

Get one of these (or anything similar): https://www.amazon.com/Lenovo-ThinkCentre-Desktop-i5-6500T-Windows/dp/B07QGLC4FW/

Get one of these: https://www.amazon.com/LEAGY-External-Sound-Card-8-Channel/dp/B07VSHCGWD/

Use EQAPO

And use some of these: https://www.kvraudio.com/plugins/distortion-saturation-plugins ... this developer has some really high quality, fairly subtle distortion plugins for free: https://varietyofsound.wordpress.com/ ... there are hundreds of options out there, many cost nothing.

From there you can find out what kind of distortion profile sounds best to you, and then perhaps buy a hardware unit that does similar things. Or just stick with DSP.

I like the approach of experimenting in the digital realm before converting to analog. I've been trying to figure out a way to apply VST plugins to music streaming services (Amazon primarily) while also preserving the native bitrate offered by the service. Plenty of tube emulators, harmonic exciters, etc, offered as VSTs.

While 'exciters' aren't exactly tube emulators, they provide a lot of the same 2nd and 3rd order harmonic goodness. I bought a Berhinger SX3040 V2 and it's been a lot of fun.

Behringer | Product | SX3040

www.behringer.com

 

[levimax]

Plug ins and emulators are not really accurate to what a tube amp sounds like as they can't interact with your speakers like a real tube amp does. @Blumlein 88 gave you good advice, I have tested tube vs SS FR and adding resistance will almost perfectly match the FR. There is a lot of hand waving about distortion and soft clipping and the like about why tube amps sound different but it is unproven and good tube amps don't have audible distortion anyway. FR is much more audible than distortion. A push pull amp like a Dynco ST 70 has about 0.75 ohm resistance ... a zero feedback SET up to 5 Ohms. You can try this for just a few dollars and depending on your speakers you may like it.

 

[Ruhled]

As a frequent tube amp user the dsp suggestion is actually a great one. You can dial in amounts of 2nd and 3rd harmonic you like without all incurring the other possible drawbacks of using tubes like hiss, hum, noise, damping, etc. I'm not saying all equipment suffers from these but many if not most do to some degree.

 

[djwalter2000]

Plug ins and emulators are not really accurate to what a tube amp sounds like as they can't interact with your speakers like a real tube amp does. @Blumlein 88 gave you good advice, I have tested tube vs SS FR and adding resistance will almost perfectly match the FR. There is a lot of hand waving about distortion and soft clipping and the like about why tube amps sound different but it is unproven and good tube amps don't have audible distortion anyway. FR is much more audible than distortion. A push pull amp like a Dynco ST 70 has about 0.75 ohm resistance ... a zero feedback SET up to 5 Ohms. You can try this for just a few dollars and depending on your speakers you may like it.

Interesting. Might be worth a few bucks to try. So how do you calculate the amount of resistance needed at the speaker to emulate the various kinds/wattages of tube amplification? To approximate the FR of a VLT IT-85 integrated what Ohm load is appropriate? And is there any consideration given to the power specs of the SS amp being used when calculating the resistance needed?

I have nothing against throwing a resistor in the mix as an experiment. Just want to do it with some level of purpose and understanding.

 

[Blumlein 88]

Interesting. Might be worth a few bucks to try. So how do you calculate the amount of resistance needed at the speaker to emulate the various kinds/wattages of tube amplification? To approximate the FR of a VLT IT-85 integrated what Ohm load is appropriate? And is there any consideration given to the power specs of the SS amp being used when calculating the resistance needed?

I have nothing against throwing a resistor in the mix as an experiment. Just want to do it with some level of purpose and understanding.

Depends upon which amp you wish to copy. As mentioned some old Dynaco amps are maybe .5 to .75 ohms. SET's are 2-4 ohms if no feedback. The VTL IT-85 according to Stereophile measurement was .85 ohms. The ST-85 was .75 ohms.

In case you didn't know, you need a power resistor. Something that would take 10 or more watts. For instance parts-express has some 1 ohm 10 watt resistors for two bucks each. 1 ohm might be a good level to try and see what you think. You could buy 4, use one for 1 ohm, parallel two for .5 ohm and series two for 2 ohms. That should give you a good experience of what difference it makes. So two per channel or four total.

 

[mhardy6647]

@BarrryBarrry (if they're still here, reading this thread, that is!) what, exactly, do you want to get/accomplish? You're getting a variety of responses pitched at different aspects of (ahem) the tube experience. I am inferring that you're looking for upstream "signal processing", so I'd encourage you to think about a "vacuum tube linestage" (i.e., active line-level preamp). This can be a very simple gizmo. Indeed, simpler is better if the active elements (tubes) are linear ones (triodes) and operated at reasonable operating points. Little or no gain will be needed for line-level inputs, so hum and noise can be fairly minor concerns.

Here's where I am going with this! A simple "linestage" circuit is easily constructed if one knows how to solder (or is willing to learn).
One won't go wrong with one of the simple suggested circuits from an RCA Receiving Tube Manual. Here's one, e.g.

source: pg. 528 of https://www.worldradiohistory.com/B...ooks/RCA-Receiving-Tube-Manual-1963-RC-22.pdf

Voltage source can be a lab-type HV power supply or a home-brew P/S. Obviously, care and understanding of the potentially lethal voltages required are necessary, but I have to think most ASR readers are at least familiar if not conversant with proper safety precautions! This ain't Best Buy's support forum!

If that is more than the OP wishes to tackle, source a good, simple, basic preamp kit sans bells and whistles.
Alternatively, our goofy frat-boy friends at Schiit make a product that is right up the OP's alley:

Schiit Audio: Audio Products Designed and Built in Texas and California

www.schiit.com

This gizmo is a passive source selector and (effectively) passive attenuator with a switch-selectable vacuum tube buffer using a "modern" 6SN7-workalike twin triode octal base tube. Schiit, to their credit, probably builds a buffer that is reasonably properly designed and implemented, unlike the $39 effects boxes made in the far east without with little or no regard to output signal fidelity.

Of course, the audible impact of a buffer, tube or transistor, should be negligible unless the impedance matching it provides provides an improvement between source and amplifier (which it could).

Trigger warning: ASR-philosophy-unfriendly editorial follows. I am 100% not convinced that any DSP games with harmonics will give you a realistic assessment of what the fuss is (i.e., may be) about vis-a-vis using vacuum tubes vs. transistors as active elements in audio circuits. The problem with models is that they tend to be over-simplified (for good, practical reasons). As such, they're useful... until they're not. Here's a case where one may substitute the real thing for the model, so why not?

Sorry, this reply got longer and more convoluted than intended! I've either had too much caffeine this morning -- or not enough.

 

[fpitas]

The problem with models is that they tend to be over-simplified

They don't have that warm glow, either

 

[mhardy6647]

They don't have that warm glow, either

I am now rolling on the floor here.

 

[fpitas]

Also, if you feed a long cable, you might want to slip in a 100 ohm resistor, in series with the cathode output to C4 etc. Followers can get unhappy and oscillate (well, maybe they're still happy) when presented with a capacitive load.