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Buffalo II - Assembly for the Electronically Bewildered.

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Suffolk Tony said:
The BP HD still runs just as hot I'm afraid Martin.
Click to expand...

Mine is running much cooler. I found that both the shunt current and the voltage pots needed significant adjustment after attaching to a load. Per the TPA recommendation, I've got the shunt running a bit over 50mA.

[New placid HD on the website? It looks the same to me. – Never mind, I see it's the mono, not the BP that's been improved.]
 
To me it looks like half a Placid HD BP. It looks narrower and longer compared to the old one. Good for integration with HP BP.
 
Experimenting with the original 2.2nf pp caps for output filter on legato. Polystyrenes are lovely for acoustic and classical, but things were sounding a bit sterile on rock, and stuff needing some balls. Still got styrenes in for the other 4.
 
The caps in this position appear to have a huge influence on the tone of legato. I'm not convinced I particularly like either the polystyrenes I had in, or the wimas - any recommendations on decent 2.2nf caps to try?
 
Hmm....looking at the datasheet in Ron's link, the resonant frequency of the 2.2nF cap would appear around 80mhz. Isn't that the operating frequency of the Sabre chip? - Not sure if that's an issue at all but I would expect that we should steer away from caps that have resonances near that frequency.

Perhaps that's why the Buffalo seems sensitive to seemingly innocuous changed in cap values and types on the Legato?
 
James Evans said:
The caps in this position appear to have a huge influence on the tone of legato. I'm not convinced I particularly like either the polystyrenes I had in, or the wimas - any recommendations on decent 2.2nf caps to try?
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I'm currently listening to an IVY-III with 4 polystyrene caps and much prefer them to the original Wimas in the kit. Perhaps they're a little lean, but the sound is so much cleaner that the choice is a no-brainer for me.

A Legato 3.1 kit is awaiting sufficient time & motivation, and it will receive 8 x 2n2 teflons that arrived recently from the Ukraine. In the meantime, I could try 4 x 2n2 teflons in the IVY-III. I'll see if I can find time & motivation this weekend to give them a go. Honestly, the current TPA kit is sounding so fine that it's hard to get off the couch to make any changes. :)
 
flashgo said:
I'm currently listening to an IVY-III with 4 polystyrene caps and much prefer them to the original Wimas in the kit. Perhaps they're a little lean, but the sound is so much cleaner that the choice is a no-brainer for me.

A Legato 3.1 kit is awaiting sufficient time & motivation, and it will receive 8 x 2n2 teflons that arrived recently from the Ukraine. In the meantime, I could try 4 x 2n2 teflons in the IVY-III. I'll see if I can find time & motivation this weekend to give them a go. Honestly, the current TPA kit is sounding so fine that it's hard to get off the couch to make any changes. :)
Click to expand...

I find audiophilia nervosa sets in much worse with legato than ivy. Ivy just gets on with it, and while I was waiting for legato to be delivered I really had no complaints. Legato brings a certain something though, and it needs to be persevered with. Just hope I manage not to destroy the solder pads on these caps.
 
James Evans said:
I find audiophilia nervosa sets in much worse with legato than ivy.
Click to expand...

I'm feeling the insidious nature of the disease at work. ;) While the TPA DAC is in pretty good shape, I've been struggling with the input signal. This includes TOSLINK vs. USB, various cables, various hardware sources, and various software players. The only satisfactory sound I've found comes from:
  1. HDTracks (or similar) hi-def music files
  2. Songbird FLAC player (other players I tried all made the sound lifeless!?)
  3. USB out of a Mac Mini port via Monster USB cable (maybe better than a generic Hing Wing cable)
  4. TeraDak USB to digital audio converter (Yes! Much cleaner than the TOSLINK off the Mini.)
  5. 75 ohm cable to TPA DAC (haven't played enough to know whether quality/expense makes any difference)
However, I still can't bust the stuttering or drop outs in the USB feed. After powering up the Mac Mini (on any of several different accounts), I get about 45 minutes of uninterrupted quality music, then the dropouts start occasionally and become more frequent with time. Same deal off a MacBookPro running on battery.

I finally got fed up and played a vinyl record. Ahhh, joy.... I feel like I can't go any further with the TPA DAC until I get the input straight, and that's a major hassle because there are so many places where it can go wrong. Maybe I'm just not cut out for digital.
 
I have changed the main cap (1000uF/35V) for one Panasonic FC 2200/25 in Placid ps delivering power for dac pcb and ...

The sound became more edgy, digital, unpleasant. I was waiting few days, hoping that the new cap will "settle down", but nothing has changed, so i soldered again the original cap in place.

Hmmm, interesting. Size matters ?

HD Placid kit arrived few days ago, i hope i can build it before my vacancy.
 
I replaced the 1nF polystyrene caps on my IVY-III with 2n2 Soviet teflons and learned 2 lessons. First, 1nF was rolling off the HFs. 2n2 is much better. Second, teflon rules! The sound is smoother, much cleaner, more open, more dynamic. Everything is right with the world (with the exception of USB). :D I'm also using teflons to bypass the feedback caps in my tweeter amp, and it's much the same experience there.

I could only find the teflon caps in 1600V, so they're kind of big. :eek:
ivy1q.jpg

I ended up fitting them under the board with double length standoffs:
ivy2z.jpg
ivy4.jpg
ivy3i.jpg


Obviously, it's a bit of a lash up. Once I've plowed through the Legato, Tridents, and digital volume control, the whole Buffalo DAC will be rebuilt in a new box, and then the teflons will go off to the sides of the board rather than underneath. I'll need a proper sidecar at that point.
 
Looking good, I'm very tempted with the whole Buffalo thing, but they never ever seem to have any on sale
 
Well it looks like not being able to bag a Buffalo was not such a bad thing the BIII is coming on sale now.
Just watch all you guys go and bag the lot :D
 
flahsgo, thanks for the info re. the Teflon caps ..... just when I thought I'd finished messing withe my Buffalo!

I don't doubt what you're hearing, but a 2.2nF cap will actually roll off high frequencies earlier than the smaller cap, although both are well above the audio band. Just shows how critical cap quality is in this position at least.
 
Sparts, the caps in question are C1-4 in the IVY-III which form low pass filters with the caps anchored to ground. So raising the capacitance should keep more HFs in the signal path. TPA originally spec'd them at 15nF, but IIRC, there was a problem with too much HF getting through and blowing up the next stage. Again IIRC, the recommended value then became 2.2nF. I had some 1nF polystyrenes in previously because that's all I had that was close, and I only had 4 of them. ;)
 
I understand what you are saying about where the caps go and their function, and you are absolutely right, however the larger cap will start the filtering action sooner, providing more filtering overall. The maths is worked out using F = 1 / (2*PI*R*C).

I've not heard about a problem with too much HF getting through, but if that's true, a smaller cap will only make it worse. Do you have a link to where this is reported. Thanks again for sharing your findings.
 
Oops, brain fart: I was thinking numerator rather than denominator. Well, there's definitely more HF, so it's probably not so much the knee as the capacitor itself that contributes to the HF. BTW, bass really rocks with the teflons, so the effects are across the spectrum.

BF#2: There was some discussion back on page 10 of this thread about the cap values, but maybe what I was "remembering" about HF issues was from the short-lived TPA Counterpoint.
 
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