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Old 25th June 2013, 02:37 PM   #471
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Quote:
Originally Posted by georgehifi View Post
Can't wait to get these BUF03's to see if they can topple the already great sounding internal buffer of the AD844, I also puchased a nice ready made pcb on ebay to make it nice and neat.
Ebay Item Number 121130571333

Also here is Walt Jung's take on the BUF03, he only seems to have concerns with distortion in openloop implementation when the load goes down too low, which will never happen in my case.

Cheers George
I'm willing to design a circuit board for a discrete version of this circuit, if you are interested. It won't be free, but I'm willing anyway. Someone needs to model it and pick the parts.
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Old 26th June 2013, 12:46 AM   #472
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That would be nice Dirk, but let's wait till I compare it to the AD844's internal buffer.

Cheers George
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Old 28th June 2013, 02:11 AM   #473
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While waiting for the BUF03 and PCB to get here. I thought I queery the pin 5 TZ h/f filter capacitor to ground type, I am using 470pf. A what do you cap experts think is the better to use
Polystyrene
Polypropylene
Siver Mica
Ceramic
or any others?

Cheers George
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Old 28th June 2013, 02:24 AM   #474
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I favour C0G ceramic myself - bear in mind that the precise point of grounding the cap tends to affect the sound as all grounds have some noise.
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Old 28th June 2013, 02:30 AM   #475
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Quote:
Originally Posted by georgehifi View Post
While waiting for the BUF03 and PCB to get here. I thought I queery the pin 5 TZ h/f filter capacitor to ground type, I am using 470pf. A what do you cap experts think is the better to use
Polystyrene
Polypropylene
Siver Mica
Ceramic
or any others?

Cheers George
I think Polystyrene and PPS sound the best. For RF I'd consider PPS SMT devices. I use those to decouple my 1541 dacs. A natural sound. Ceramics can ring with impulses or dynamics. Never met a ceramic that sounded good. Just an opinion..... Don't forget to heatsink the BUF03. They cook....
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Old 28th June 2013, 02:36 AM   #476
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Quote:
Originally Posted by georgehifi View Post
While waiting for the BUF03 and PCB to get here. I thought I queery the pin 5 TZ h/f filter capacitor to ground type, I am using 470pf. A what do you cap experts think is the better to use
Polystyrene
Polypropylene
Siver Mica
Ceramic
or any others?

Cheers George
George, all of those are good dielectric types. The ceramic should be an NP0/C0G type dielectric only.
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Old 28th June 2013, 02:42 AM   #477
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Yeah got two nice TO-99 heatsinks for them
I'll tell you though, I was listening to it yesterday and it was so impressive, that the BUF03 is going to have it's work cut out trying to beat the AD's internal buffer, as I said before I think no one has heard how good the internal buffer is yet without sacking the i/v stage and stopping any current starvation from happening.

Cheers George
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Last edited by georgehifi; 28th June 2013 at 03:00 AM.
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Old 28th June 2013, 02:52 AM   #478
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So at the moment I'm using 1% nos 470pf mil spec Styro's? Clear slight green tinge barrel body, good solid ends not flimsy and a bit heavier than the standard clear styro's, these should be fine?

Cheers George
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Old 29th June 2013, 05:29 PM   #479
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Default Polystyrene caps

Quote:
Originally Posted by georgehifi View Post
So at the moment I'm using 1% nos 470pf mil spec Styro's? Clear slight green tinge barrel body, good solid ends not flimsy and a bit heavier than the standard clear styro's, these should be fine?

Cheers George
Sounds fine to me. I bough some Siemans capacitors many years ago and they were of heavy construction. Worked perfectly. Polystyrene capacitors are usually tin foil and Polystyrene film. Don't think the green is an issue.
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Old 4th July 2013, 11:54 PM   #480
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Got the BUF-03 yesterday put it in instead of the AD844's own buffer, dc offsets steady at .1 to .2mV after warm up, when cold I get around 5mV, also a mute circuit is needed as it in conjunction with the AD844 gives a hefty 5v switch on and off thump for a second. I have very nice TO-99 cast aluminium heatsinks for them they run HOT, and no they are not oscillating, 15v rails.
The 844's buffer will not drive my Sennheiser HD650 (300ohm) without gross distortion where the BUF-03 does it no trouble, the BUF-03 has far lower output impedance and higher current than the 844's buffer.
On my system proper both are driving a 50kohm total load of the input of my poweramps (bi-amped 100kohm each) I use the digital domain volume on the cdp, it is in the same position for both buffers almost full up.

Listened all night. I am perplexed, the sound is so different and opposite to what I thought would happen, the AD844 is super fast, very dynamic, very detailed, sweet highs, very extended both ends and kicks like a mule in the bass, and has subterranean bass. It can get in your face sometimes with bad cd's
The BUF-03 I thought with it's far low output impedance and far higher current would be even more of the above. But no it does exactly what pure class A poweramps do, things seem mellower/relaxed (almost tube like) it's all there but it's toned down a little like someone has slipped a tube in somewhere, but more so like a good class a/b poweramp which has been biased up almost into full class A.
Both are great to listen to but as to say which is right, I cannot say yet, I need to listen much longer to see if I miss the 844's attitude. One thing though the BUF-03 has got the thumbs up for driving the Sennheiser phones.

Cheers George
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Last edited by georgehifi; 4th July 2013 at 11:56 PM.
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