[buzzlulu]

Gorgeous!!
Anyone doing commissioned builds on these - in the States?

 

[paradoxper]

Some CFA2 love...

IMG_5859 (1)

IMG_5858

IMG_5856

IMG_5867

Great build @johnwillmclean. Your builds have always aesthetically influenced mine from the HV to the T2. Thanks.

 

[johnwillmclean]

Thanks guys!

For some context before the one liner sound impression below, the GRLVs are set up for +/-30v, when I bench tested everything I settled for 180mA current which got quite hot, now with everything cased up months later it’s only just warm and the current has dropped to around ~140mA, so I’m dialling it all up to 200mA, the ambient temp now is a lot colder so that must be what's happening.

So impressions at ~140mA sounded the best I’ve exprienceced with HD800s... I don’t know what 200mA will get me....

 

[Dukei]

Some CFA2 love...

IMG_5859 (1)

IMG_5858

IMG_5856

IMG_5867

That's one way to do your first post. Superclean! How big are those transformers, 120VA each?

 

[johnwillmclean]

thanks!

They’re 100VA each, meant to include these shots, base and rear sides:

IMG_587d6

IMG_5877

 

[paradoxper]

Thanks guys!

For some context before the one liner sound impression below, the GRLVs are set up for +/-30v, when I bench tested everything I settled for 180mA current which got quite hot, now with everything cased up months later it’s only just warm and the current has dropped to around ~140mA, so I’m dialling it all up to 200mA, the ambient temp now is a lot colder so that must be what's happening.

So impressions at ~140mA sounded the best I’ve exprienceced with HD800s... I don’t know what 200mA will get me....

Throw a planar into the mix and let us know what you think.

 

[Benny-x]

What's the difference between that balanced, dual mono CFA2 vs. the CFA3?

 

[RudeWolf]

The quad CFA2 ensemble will only take and output BAL signal. The CFA3 has a completely different input stage and it can be built to use no negative feedback.

 

[Benny-x]

Ok, I reread your opening post. So the CFA3 is a special input stage (ZNF or SuSy) + CFA2 amplification (gain?) stage + GRLV PSU ?

Whereas the CFA2 above is CFA2 amplification stage + GRLV PSU?

Meaning the big (only?) difference is the input stage? And specifically how it can do built in conversion from SE<->BAL with the inputs and the outputs?

I'm not too familiar with the sonic differences of the feedback style, but earlier in this thread other owners reported not much difference.

I'm just trying to get a handle on what's going on.

 

[RudeWolf]

So the CFA3 is a special input stage (ZNF or SuSy) + CFA2 amplification (gain?) stage + GRLV PSU ?

Yes, more or less. CFA3 has a bit stripped down CFA modules, compared to the CFA2.

Meaning the big (only?) difference is the input stage? And specifically how it can do built in conversion from SE<->BAL with the inputs and the outputs?

Pretty much. If you only want SE, I'd prolly go with 2xCFA2. Want only BAL? 4xCFA2 is a legit choice. Want SE/BAL natively and don't need ZF? Get one of the input stages and hook 2xCFA2 per channel.

 

[Benny-x]

Yes, more or less. CFA3 has a bit stripped down CFA modules, compared to the CFA2.

Do you know anywhere that the "bit stripped down" is explained? I'd be aiming for the best sonics via balanced inputs -> balanced outputs. My DAC is best balanced and I've converted most of my headphones to balanced.

The ZNF vs. SuSy input option is interesting, but it's not anything I know about.

 

[Pars]

The output stage of the CFA3 doesn't really look stripped down from the CFA2 to me, but I haven't compared them closely.

On the CFA3 that I worked on, I couldn't tell much if any difference between the SS vs. ZF modes either.

 

[tunes]

So just a quick follow up. listened for a bit last night and figured I should share some more of my non professional broken ear thoughts.

First I had basically given up on SS amps due to 2 main reasons. Treble harshness, and lack of body/thickness to the sound vs what I was hearing using tube amps with good tubes. This always made me think, hey, you love a nice thick warm amp and tubes were my answer to what I wanted. Well then I was bored, and and wanted an SS amp for random use, and I saw the CFA3 come up. Ended up buying a Dynalo MK2 Mini, and thought oh this sounds very nice. Warm, a bit thick, but still had a bit of that treble harshness but I appreciated the sound. so I went and commissioned the CFA3. This came after I chatted with @paradoxper and @RudeWolf. Those 2 just basically planted a seed in my head that I couldnt get out and spent all my money.

The process was fantastic and after the end result I can 100% recommend to anyone that is interested.

First, the idea of a more neutral amp vs the dynalo scared me a bit, but went with it anyways. The treble, to me this is the biggest thing about this amp. It extends and is airy and sounds lovely. But there is no harshness, like my friends and I joke about headphones and amps that "stab" you on those bright bright songs. We use dua lipa as a stab measuring stick. Yes the amp will show you all that brightness, but the harshness isnt there. I dont even know how to explain it, who the hell knew treble on headphones can be loud and extended but without feeling like someone is stabbing you through the ears? For me treble is perfect, i cant really explain it. its airy controlled, extended, detailed, and not harsh. this is actually probably the most amazing part of this amp to me.

Next is the mids. I listen to the mids and im like oh thats pretty good not bad. Why is this surprising? I am coming from a 300b tube amp, which to me is arguably the "mid" king. 300b tubes have that lush romantic mid that all the fans crave and have pushed NOS tube prices into the stratosphere. for me not to feel like I was really wanting more and lacking anything is actually an amazing achievement.

Bass, i was kind of expecting, but there is a heft to the low end that is fantastic. It has great control all the way to the bottom if your headphones can handle it, and loads you with as much details as your headphones can provide. The textured bass out of the cfa3 is great, and probably the best ive heard.

I do need to do some more A B testing with my tube amp and maybe toss in the dynalo mini as well just for a reference point. But atm, the songs have weight and thickness to them, and the signature/SQ is perfect for me. Also has a bit of liquidity that I am sensing that makes it feel a little bit like a tube amp. Overall its just a really incredible amp. But hey who knows, maybe its the honeymoon phase and I will hate it by next week haha.

Oh and I also have speaker taps on my CFA3, and they are driving my Passive Aggressive Speakers (i call them wife speakers) for my computer fantastically. its a 82db sensitivity speaker with recommended 40w rms+ amp to drive them. CFA3 when cranked will make these tiny little things vibrate my desk and sound extremely full. I listen to them on my desk at around 9-10oclock on the cfa3 on low gain.

Oh and just to add, the headphones ive tried is a 4 screw HE6 and zmf verite closed.

How do you like the ZMF Verite closed and have you compared it with the likes of Abyss TC, Susvara and SR1a?

 

[paradoxper]

Seems the third wave of CFA interest is crashing in. Sorry Miroslav. Thanks Kevin.

 

[Dukei]

Seems the third wave of CFA interest is crashing in. Sorry Miroslav. Thanks Kevin.

Haha, swamped this month with the tube input exploration and an Uberamp-RAAL build. Might start a separate thread for that one.