[L0rdGwyn]

I’ve found Obbligatos (Obbligati?) to offer most of the benefits of PIO in a smaller (and more affordable) package.

Seen here as output coupling caps in my NOS DAC (modded Teradak Chameleon):

Looking forward to trying them out! Should have them Monday or Tuesday.

 

[whirlwind]

Polished up my Auteur today and conditioned the leather, been a while since I tuned it up. I'm back in the headphone saddle, baby! Honestly been a while since I've listened on 'phones, been wrapped up in speaker world for a while.



I decided I did not like the Auricap XO in this amplifier, they have been temporarily swapped back to the Solen Fast-CAP MKP from the prototype. I found they were imparting a harshness/sibilance to the upper midrange and treble. They'll get another chance, I picked up some other caps to try out, going to have a shootout between Obbligato Gold, ClarityCap CSA, Auricap XO, and the Solens when they are all in house.

So please tell about the sound with the Auteur....wood is killer on that headphone!

 

[L0rdGwyn]

So please tell about the sound with the Auteur....wood is killer on that headphone!

Of course!

So, with the globe RCA 841, this is not a "tubey" amplifier due to the low distortion (although that can be tuned with the shouldered Hytron 841). The sound is very clean, without the warmth that you might expect with a tube amplifier. What it maintains from the tubes is excellent transparency and dynamics. The thing that stands out most to me is the low end, it is very well-defined and hits hard! Really great with bass-driven music like rock and EDM, pairs well with the Auteur which has a very nice low-end extension for a dynamic headphone. Would love to pair it with the Verite at some point, we'll see how the sound changes with the cap rolling

 

[Tjj226 Angel]

Are these caps for output coupling? What are the chances you could direct couple instead?

I just want to take a second and say that anything and everything can be directly coupled to anything else. As long as you are willing to deal with the offset voltage both positive and negative, then anything is possible.

Just remember that with a single ended amplifier, you will almost always have some sort of capacitor in your audio path. In a direct coupled amplifier, the last power supply capacitor is in the audio path.

So you have to be semi judicious about what you do and how you do it. All that glitters is not gold and what not.

 

[Xcalibur255]

@L0rdGwyn

I was a little surprised to see you preferring the Solen to the Auricap. With this new discovery the Auricap might vindicate itself now. There's nothing "wrong" with the Solens but I've heard/owned several amps that use them (still have one of them) and while they are very good at not doing anything "bad" to the music in terms of adding sibilance or bite they also make the music feel kind of dead and lifeless IMO. Stuff like this is always a very tricky balancing act.

Then again the way you're describing the sound of the amp right now maybe the Solen has the right synergy for this particular design.

 

[whirlwind]

Of course!

So, with the globe RCA 841, this is not a "tubey" amplifier due to the low distortion (although that can be tuned with the shouldered Hytron 841). The sound is very clean, without the warmth that you might expect with a tube amplifier. What it maintains from the tubes is excellent transparency and dynamics. The thing that stands out most to me is the low end, it is very well-defined and hits hard! Really great with bass-driven music like rock and EDM, pairs well with the Auteur which has a very nice low-end extension for a dynamic headphone. Would love to pair it with the Verite at some point, we'll see how the sound changes with the cap rolling

Thanks for this...sounds like the bass goes low and slams really well.. I like when the music has some weight and meat on the bones....sounds great.

 

[CJG888]

I‘m also not a great fan of Solens. Like Ansars (do they still make them?), they work and are better than RS Film caps. However, one of the first things I did with my Opera Consonance Cyber 20 was a „solenectomy“ followed by a transplant of a couple of Audio Note copper foils...

 

[L0rdGwyn]

@L0rdGwyn

I was a little surprised to see you preferring the Solen to the Auricap. With this new discovery the Auricap might vindicate itself now. There's nothing "wrong" with the Solens but I've heard/owned several amps that use them (still have one of them) and while they are very good at not doing anything "bad" to the music in terms of adding sibilance or bite they also make the music feel kind of dead and lifeless IMO. Stuff like this is always a very tricky balancing act.

Then again the way you're describing the sound of the amp right now maybe the Solen has the right synergy for this particular design.

I suspect the major issue with the sibilance was actually the Cree FET, swapping it out for the AOT1N60 had a more significant impact than the cap swap. Entirely possible the Auricaps had some negative synergy with the Cree and will fare better with the new chip. I don't expect the Solens will make the final cut, but while they don't add anything, they also don't add anything, if you know what I mean. I'll be very curious to see how the Auricaps sound with the A&O FET. Once I have my swatch of caps in house, I will A-B them with alligator clips and declare a winner, going to just leave the Solens in for now because frankly, I'm tired of going back inside the amp lol.

I‘m also not a great fan of Solens. Like Ansars (do they still make them?), they work and are better than RS Film caps. However, one of the first things I did with my Opera Consonance Cyber 20 was a „solenectomy“ followed by a transplant of a couple of Audio Note copper foils...

The options for compact 6.8uF 600V films are pretty limited. The Solens, Auricaps, Claritycap CSA, and Obbligato Gold will all fit in the dedicated space. Not sure if Ansars are still available, if anyone finds others that fit in roughly a 40mm x 56mm space, I am all ears

 

[CJG888]

I just had a look: Cricklewood Electronics still sell Ansars (limited range of values though- probably old stock).

 

[bcowen]

So turns out both changes I made between the prototype and the final version of the 841 amplifier were failures

As I mentioned, I was hearing a certain sibilance and "bite" to the upper midrange that became somewhat fatiguing. First I swapped the Auricap XO back to the Solens, which was an improvement, but something was still "off" compared to what I had heard in the prototype. Did I miss this sibilance then? The only other major change I made was swapping the source follower FET from the Alpha & Omega AOTN160 to the fancy SiC Cree C2M1000170D. So what the heck, let's swap it back and see what happens.

Bingo.

The venerable AOTN160 fixed the sibilance, increased the soundstage, and improved the dynamics. So, guess the SiC FET isn't the bee's knees after all. Could be application specific as I did not notice any of these issues when messing around with the Cree chip in my 801A prototype.

So looks like I'll have to roll some different FETs in addition to the output caps, but happy with the AOTN160 for now, the sound kick's ass once again. Maybe I can throw together some sort of modular source follower board to make A-Bing FETs easier

Don't think I ever showed the frequency response of this amplifier.

So it's like 1dB down at 20 Hz? Sure hope you can fix that. And I'm ignoring the ~0.3db droop at 20k because at my age I can't hear above 6k anyway. I'm pretty sure the frequency of my wife's voice is 6.1 kHz.

Honestly that's pretty damn impressive. I mean like way awesome, dude. Congrats! I'm just mad at you for even suggesting FET rolling. Like I need another rabbit hole, and I can already see @Zachik foaming at the mouth which is not a pleasant envisioning.

 

[bcowen]

I’ve found Obbligatos (Obbligati?) to offer most of the benefits of PIO in a smaller (and more affordable) package.

Seen here as output coupling caps in my NOS DAC (modded Teradak Chameleon):

Those look very nicely made (from what I can see). I've never tried them, but thanks for the rec!

 

[L0rdGwyn]

So it's like 1dB down at 20 Hz? Sure hope you can fix that. And I'm ignoring the ~0.3db droop at 20k because at my age I can't hear above 6k anyway. I'm pretty sure the frequency of my wife's voice is 6.1 kHz.

Honestly that's pretty damn impressive. I mean like way awesome, dude. Congrats! I'm just mad at you for even suggesting FET rolling. Like I need another rabbit hole, and I can already see @Zachik foaming at the mouth which is not a pleasant envisioning.

That's 0.5dB at 20Hz, thank you very much! Who knows when I'll get to messin' around with the FETs, the AOT1N60 is hard to beat, maybe I'll just kick back and enjoy the music for once after I roll a bunch of caps of course.

 

[Zachik]

I can already see @Zachik foaming at the mouth which is not a pleasant envisioning.

The heart wants what the heart wants...

 

[Paladin79]

I am nearly finished with my latest Incubus build in Lacewood. I do have some wiring to finish tomorrow morn then I will begin testing before it goes out as a loaner. I never have been a fan of metal cabinets so I use hardwoods. This one is lacewood with rainbow poplar splines and it will have a tiger maple bottom plate.

 

[L0rdGwyn]

Giving the shouldered Hytron 841 a listen this morning. These have a second harmonic dominant distortion profile in this amplifier at higher levels than the globe RCA 841, offers a bit of a different flavor, slightly more warm sounding, always nice to have options



Working on getting my hands on a pair of globe General Electric 841, we'll see how they stack up against the others.