[bOTL]

Hi,

I recently acquired a DAC and amp for Stax headphones built by a local amp/dac builder. The sound is a quantum leap over everything I have ever owned before with Stax L700 headphones .
However, when I opened them up i noticed that the caps used are no-name and I wonder if there are sonic gains to be made by upgrading them?

The DAC uses a dual mono AKM AK4497EQ chip and Russian tubes 6Н16Б for buffer.


Here is the output stage


The amp is a OTL with 6Н17Б and 6S4A tubes.


These seem to be the interstage coupling caps


And these the final coupling caps


Any recommendations, where to start?

[Tyson]

No images are showing up for me.

[srb]

No images are showing up for me.

Nor for me.

I always check that photos display and links function properly either in Preview or immediately after posting.

[bOTL]

Strange. Maybe because I'm a new member It doesnt allow me to add pictures.

[bOTL]

Let me try to repost pictures (now i downloaded them and uploaded instead of linking).

The DAC uses a dual mono AKM AK4497EQ chip and Russian tubes 6Н16Б for buffer.


Here is the DAC output stage


The amp is a OTL with 6Н17Б and 6S4A tubes.



here is what seems to be the interstage coupling cap


And here the coupling cap

[bOTL]

Ok, so i checked, all yellow ones are coupling caps. Will there be any audible improvement with changing them to say Audyn Cap True Silver which at 25x60mm (1x2.3inch) is probably max i can fit in there. 
Or is Roger A. Modjeski correct in saying that there is no difference since there is virtually no current going through them and no voltage drop across them? https://www.audiocircle.com/index.php?topic=126885.0

If there is a difference, which relatively small form factor 630v+ coupling caps would you recommend that would outperform Audyn Cap True Silver?

[Early B.]

Cap changes can make a huge improvement. However, in your case, I wouldn't do it. Good sounding caps are often costly and quite a bit larger than the original ones. Your money will be better spent elsewhere. 

[bOTL]

Thanks Early B. Thats what i've read as well that upgrading caps can result in improvements, but is this the case in Coupling Cap duties as well? Currently there are the cheap chineese MKP coupling caps, will there be audible improvements by changing them for something better? I dont mind spending few hundred usd on better caps if this actually improves the sound, but does it?

What other components could yield improvements? My Alps27 pot is also shot, will changing it to something better (RK50 or CP2500) result in aubible improvements?

[Early B.]

I dont mind spending few hundred usd on better caps if this actually improves the sound, but does it?

A few hundred USD will allow you to upgrade to a better sounding amp or DAC.

[rollo]

  There is a site that reviews caps. www.humblehomemadehifi/cap.com


charles

[Mike B.]

I bought some of those Audiophiler caps off ebay. They are not a good sounding cap IMO. I think pulling them and replacing them with a better one would be worthwhile.

[randytsuch]

For tube gear, there are LETHAL voltages present.
Not sure if there is a bleeder resistor, that will dissipate the high voltage after you turn off the DAC/AMP.

You need to be able to check to make sure the high voltage is gone before attempting to do anything.

Randy

[Freo-1]

I'm partial to Mundorf caps, especially for coupling duty.  I've tried other brands, but always wind up going back to Mundorf.  Their Silver/Gold caps are among the best sounding I've come across, and they hold up.   

[Tyson]

The thing I've found with Caps - if there's signal going through it, then you ought to use something made of copper.  I've tried copper caps from Audyn, Jupiter and Miflex.  IMO the Miflex caps the best of the lot and are also the cheapest.

And if you think about it, it makes sense.  You wouldn't make an interconnect or speaker wire out of aluminum or tin, would you?  If not, then why would you use signal caps with tin or aluminum?  Copper all the way baby!

[randytsuch]

The thing I've found with Caps - if there's signal going through it, then you ought to use something made of copper.  I've tried copper caps from Audyn, Jupiter and Miflex.  IMO the Miflex caps the best of the lot and are also the cheapest.

And if you think about it, it makes sense.  You wouldn't make an interconnect or speaker wire out of aluminum or tin, would you?  If not, then why would you use signal caps with tin or aluminum?  Copper all the way baby!

Did you use the KPCU (copper oil) or the KFPM (copper poly) caps?

Randy

[Tyson]

Did you use the KPCU (copper oil) or the KFPM (copper poly) caps?

Randy

Copper Oil, KPCU.  I get then from Jeff at Sonic Craft.

[Freo-1]

Not a fan of Jupiter caps.  I had a set installed in a a pair of DIY amps that use 6BL7/6883B tubes.  Although they were rated for temperature/voltage being used in the amp, they none the less melted over time, and did not sound all that good to begin with.  They sounded closed in, and never opened up.  Wound up replacing the Jupiter caps with Mundof Silver/Gold caps, and the amps had a remarkable transformation in performance.   No issues with heat or voltage with the Mundorfs, and the amps sound fantastic. 


BTW, the 12 volt version of the 6146B i(6883B/8552) is a well kept secret.  As an output tube, it is one of the best sounding, most reliable, and reasonably priced output tube options for DIY options available.  The tube has 35 watt plate dissipation, rugged, readily available NOS at a reasonable price, and sounds better than the current production 6550's, and most of the current production KT88's as well.   As long as one pays attention to the screen voltages, a 100 watts from a pair is achievable. 

[genjamon]

I just read the review of the Miflex on Humble Homemade Hifi.  Tyson, what did you think of that review's comparison with the Jupiter?  What are your thoughts on the Jupiter comparison relative to HHH?  I have Jupiter's as output caps in my preamp, but have had reliability issues with them and have been curious to try another brand if I can find one that's as good as the Jupiters for equal or lesser cost.  Don't think Duelunds would fit physically or in the pocketbook.

[OzarkTom]

Dueland Alexanders might fit. But the ones I used took over 500 hours to break in. And those are expensive.

[Tyson]

I just read the review of the Miflex on Humble Homemade Hifi.  Tyson, what did you think of that review's comparison with the Jupiter?  What are your thoughts on the Jupiter comparison relative to HHH?  I have Jupiter's as output caps in my preamp, but have had reliability issues with them and have been curious to try another brand if I can find one that's as good as the Jupiters for equal or lesser cost.  Don't think Duelunds would fit physically or in the pocketbook.

They are at least as good as the Jupiters, maybe better.  Remember that Humble Homemade Hifi is using them at the speaker level and I'm using them in my tube amps. 

BTW, I've also had issues with the Jupiters 'melting'.  It doesn't affect reliability in my setup but it's weird to see it the first few times.  The Miflex seem to be more robust re: resistance to heat.