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Headphone tube amp components upgrade

Hello folks!

Im doing some experiments on tube circuits. I have this schiit audio valhalla fully tube headphone amp. I would like to know which kind of upgrade or customization i can make on this. Is it possible to get a cleaner sound or refined sound changing, for exemple, the capacitors for better quality ones? Or maybe the transformadores?

I would like to get the best out this circuit, any tips for upgrade?

Thanks!

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I would only replace old electrolytics as found in a vintage valve amplifier.

However, I'm sure you'll get many suggestions for 'audio grade' replacements!

The quality of the output transformers contributes greatly to the sound of a valve amp. Problem is finding suitable upgrades and, if you do, they will almost certainly be larger than the existing ones which fit neatly on to your circuit board.
 
Actually, the transformers are power transformers. The amp is OTL. The red Wima "box" caps are decent but an upgrade might help. However, anything "better" will be MUCH larger.

The Valhalla is pretty much an optimised design as it stands It's tight chassis confines don't allow much room for bigger and "better" parts.

If there are a lot of hours on this amp you might want to replace the tube set. Getting a well balanced and matched set from someone like Jim McShane might yield a sonic improvement.

What 'phones are you using? Getting a better pair might yield the improved sound you are looking for. It would save spending time and money chasing small improvements in the amp.

Cheers, Steve
 
Im not using as a headphone amp, im using as a color box... Creative coloration for recording. Reamping áudio signals. Then im really experimental on this. I want to try ways to improve and refine audio signal with the warmth of tube circuit.

What do you think would be the First step to upgrade components? Capacitors? I want It sounding warmth but cleaner. I want to refine the sound.

Thanks!
 
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PRR

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> If is possible to change the headphone output into line out.

A headphone out is usually a beefy line out. Just adapt the connection.

Headphones were FOR connecting to "lines", meaning telephone lines. There's been a lot of history but studio line level is telephone line level, and older studio headphones connected to or across studio lines. The newer fad for 32 ohm phones would not suit classic studio lines, but the reverse (phone out driving line) still works OK.

If you had to meet a Pro Spec I would wonder about maximum output. But in a "color box" the point is moot.
 
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On the audiosciencereview.com web site there is a technical review of this amplifier. It is a OTL design with 6H1N (6N1P) driver tubes and 6H6N (6N6P) output tubes. According to the measurements, I believe that if fits your goal perfectly. It is designed to produce a very high second harmonic distortion and it does have a 75 ohm output impedence, so it is more a color box than a standard headphone amp. Replacing the volume control is a common upgrade to get better channel matching, but this amplifier does use an alrealy good Alps RK27 potentiometer. If you want less distortion, a schematic is required. The clipping is higly asymmetric, this means that the resistor values have been selected to bring the tube working point near clipping to get the desired strong tube distortion. It could be possible to change the values and get a better linearity. My OTL headphone amplifier with ECC88 and 6N6P tubes does have little harmonic distortion. It is a simple design, you should be able to trace the schematic from your circuit board pretty easily. Measuring the anode supply voltage would also help.
 
> If is possible to change the headphone output into line out.

A headphone out is usually a beefy line out. Just adapt the connection.

Headphones were FOR connecting to "lines", meaning telephone lines. There's been a lot of history but studio line level is telephone line level, and older studio headphones connected to or across studio lines. The newer fad for 32 ohm phones would not suit classic studio lines, but the reverse (phone out driving line) still works OK.

If you had to meet a Pro Spec I would wonder about maximum output. But in a "color box" the point is moot.

Quite interesting! And yes i made an adapter cable and It Works Very well! Im using It with output volume all way up and sounds Very well. The Second harmonic reaches maximun level with high volume.
 
On the audiosciencereview.com web site there is a technical review of this amplifier. It is a OTL design with 6H1N (6N1P) driver tubes and 6H6N (6N6P) output tubes. According to the measurements, I believe that if fits your goal perfectly. It is designed to produce a very high second harmonic distortion and it does have a 75 ohm output impedence, so it is more a color box than a standard headphone amp. Replacing the volume control is a common upgrade to get better channel matching, but this amplifier does use an alrealy good Alps RK27 potentiometer. If you want less distortion, a schematic is required. The clipping is higly asymmetric, this means that the resistor values have been selected to bring the tube working point near clipping to get the desired strong tube distortion. It could be possible to change the values and get a better linearity. My OTL headphone amplifier with ECC88 and 6N6P tubes does have little harmonic distortion. It is a simple design, you should be able to trace the schematic from your circuit board pretty easily. Measuring the anode supply voltage would also help.

Thanks for all this information, its quite interesting. Im glad this headphone amp can be used as a color box and i love How It sounds, but i fell It can sound Just a bit more refined. Which do you think would be a First step ob this upgrade? Im thinking about change 6N1P for ECC88. What about the electrolytic capacitor? Would it improve sound in any way? Just remembering I dont care to use bigger components, If It give me better sound. Thanks!
 
For "colour" try replacing the Wima box caps with PIO caps. The effect might be quite subtle. Try some 6DJ8 tubes instead of the 6N1Ps.

S.

Thanks Steve!

Im doing some search and yes 6DJ8 seems to be a better tube than 6N1P, probably a good step on sound refinement.

About capacitors, should I look for exact same specs, changing Brand only for PIO as u suggest? Any tip to get right values on this circuit or the only way is removing the capacitor and measure It? Thanks!
 
One thing I noticed doing some measures was that when signal come back from valhalla It comes with some sub noise. Some 20hz hum that oscilates. Its low level not quite hearble but i supose It might cause some changes in the low end. Could It be some eletrical issue, coming from electrical network? Is there something I can try to filter that hum out? Thanks
 
Wima caps usually have the capacitance and voltage printed on the side.

Sounds like you will be using this in some sort of recording situation i.e. lots of components connected together. There's a reason pro gear runs balanced, the elimination of hum looks and other interference. The solution: transformer$.
 
Wima caps usually have the capacitance and voltage printed on the side.

Sounds like you will be using this in some sort of recording situation i.e. lots of components connected together. There's a reason pro gear runs balanced, the elimination of hum looks and other interference. The solution: transformer$.

Which Transformers do u suggest me? And How expensive we até talking about? Thanks
 
I Just Saw the audiosciencereview.com Review and measures, and I see Valhalla is a bad circuit, really noisy and weird.

Well... I need a good tube coloring for audio recording but I need it to be as clean as possible. Can you guys suggest me some DIY project that I can get a clean tube sound?

I'm a newbie in electronics, but I can learn fast. Is there some (not so difficult) project I should check? Or should I bother trying some upgrades in Valhalla?

Thanks!
 
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Well if you want tube sound, noisy and weird is where you start. But seriously, what do you consider "tube sound?" Some years ago I remember someone selling a mike preamp, or some sort of intermediate box using a tube, a 12AX7 IIRC. It had a control that would allow the user to crank up the "tube sound." Likely this control cranked up the even order harmonic distortion. This can probably be simulated now with digital effects. Start with the recording effects software sellers. Many of these have emulated the effects of classic analogue effects boxes.
This forum is, in theory at least, about using tubes not for "tube sound" but just good sound using tubes. A headphone amp is probably not the best place to start looking for "tube sound."

Cheers, Steve