Yes I saw these, but they are and look too new, like they are fakes, then you have one guy trying to sell much older used pulled ones for a fortune.
Want to keep things simple if I can, plus there's this thing Jocko Homo once told me that dc servo's are not a good thing, try not to use them if possible.
Cheers George
Not sure why you're so afraid, but anyway, these look old as dirt:
Ad BUF03AJ Can 8 Analog Buffer Voltage Follower | eBay
Notice how the leads are cruddy.
These also look like they've been lying in a box in someone's shed for 20 years:
http://www.ebay.com/itm/1-Pieces-BU...112?pt=LH_DefaultDomain_0&hash=item1c1db5b1e8
You can always ask the seller if they are genuine AD, NOS, etc.
Ad BUF03AJ Can 8 Analog Buffer Voltage Follower | eBay
Notice how the leads are cruddy.
These also look like they've been lying in a box in someone's shed for 20 years:
http://www.ebay.com/itm/1-Pieces-BU...112?pt=LH_DefaultDomain_0&hash=item1c1db5b1e8
You can always ask the seller if they are genuine AD, NOS, etc.
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Got 2 from from here via Torchwood421 he's kindly going to post them to me at least I know they will be originals. Fingers crossed these will be even better than the Ad844's own buffer.
The LME49610/49600 have got the specs, but to get rid of the 60mV of DC without dc servo I have no knowledge how to do, maybe another offset nuller that abraxilito did for the PCM1704 for me would work here to? But it's getting complicated.
http://www.diyaudio.com/forums/atta...-v-pcm1702-20dc-20offset-20null-20circuit.jpg
Cheers George
The LME49610/49600 have got the specs, but to get rid of the 60mV of DC without dc servo I have no knowledge how to do, maybe another offset nuller that abraxilito did for the PCM1704 for me would work here to? But it's getting complicated.
http://www.diyaudio.com/forums/atta...-v-pcm1702-20dc-20offset-20null-20circuit.jpg
Cheers George
The reason why I would like to try the BUF03's, is that the internal buffer of the AD844 in open loop mode has got a question on it.
As good as it sounds, and it is very good, when I load it down with 100ohm it's output has droped by half, this indicates to me that in open loop mode it's output impedance is not as the specs say 15ohms, but it is really 100ohm output impedance.
This is not a great concern, but with the halving of the signal with the 100ohm load there is also quite a bit of xover distortion (probably the internal 80mA short circuit protection being applied) as well seen on the scope, not that in pratice it will ever see 100ohm load, this is the questionable part for me, and why I would like to give the BUF03 a go.
Cheers George
As good as it sounds, and it is very good, when I load it down with 100ohm it's output has droped by half, this indicates to me that in open loop mode it's output impedance is not as the specs say 15ohms, but it is really 100ohm output impedance.
This is not a great concern, but with the halving of the signal with the 100ohm load there is also quite a bit of xover distortion (probably the internal 80mA short circuit protection being applied) as well seen on the scope, not that in pratice it will ever see 100ohm load, this is the questionable part for me, and why I would like to give the BUF03 a go.
Cheers George
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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
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
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Hi George, Please let us know how it turns out... I hope to get the 844's in the next week or so. Going SOIC 16. I think that could be easier to stack.
Yeah, in audio we rarely see lower than 10K, so that should not be a problem. No 50 Ohm video drive.
The only think that concerns is DC stability without the use of feedback, but it should be OK, just null the final output, but there will be a small offset on Pin 5 of AD844.
Cheers, Joe
That's already been addressed in previous posts courtesy of abraxilito's dc offset nulling circuit for the PCM1704k, which holds steady at .1mV on pin 5 TZ of the AD844
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.
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.... 
George, all of those are good dielectric types. The ceramic should be an NP0/C0G type dielectric only.
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
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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Polystyrene caps
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.
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.
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
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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