[MisterX]

Quote:

Originally Posted by Glassman 1) remove R12 (original PPA v1.0 artwork) and put 100pF polypropylene cap there instead (this position is re-marked as C14 on my modified artwork) 2) short leads of C14 with R14 using solder bridge from underside of the board

http://www6.head-fi.org/forums/showp...&postcount=568

Nuff said?

 

[__redruM]

Got it, thanks. So my version is correct.

Do I need to protect the bottom of the buffer? There seems to be plenty of places for it touch on the sockets.

Edit: I went ahead and put some electrical tape on the bottoms, and I'm up and running!

Cool LEDs!

 

[bg4533]

Covering the bottom of the buffer isn't necessary, but is probably a good idea. If you cut your soldering very close to the board it shouldn't contact the sockets. Either way the soldering should be cut down so the buffers fit securely in the sockets.

 

[bas]

Well, I was searching the thread for schematics... I was really quite pleased with myself for 'discovering' the "Search this thread" facility.

Quote:

Originally Posted by morsel Not publishing schematics of the Glassman buffer gives the impression that it is a commercial, proprietary product, or has something to hide. This secrecy is not in the spirit of the PPA project or the DIY community. Someone could examine his buffer and figure out the schematic if they were so inclined, but it would be far better if Glassman posted the schematic instead of teasing the community with vague claims. Is this DIY, or is this a commercial product?

Oh well. I'm not looking for a buffer specially for the PPA. So I don't care about the pcb's nifty design; surely though, the PCB+kit must be very nice for PPA owners. Cheers, Ben

 

[__redruM]

Quote:

Originally Posted by bg4533 Covering the bottom of the buffer isn't necessary, but is probably a good idea. If you cut your soldering very close to the board it shouldn't contact the sockets. Either way the soldering should be cut down so the buffers fit securely in the sockets.

I did have issues without the "Cover." The amp wouldn't power up without them. I think they cause a short between V+ and V-. Luckily nothing burnt up. I had to cut, file, and cover the bottom.

 

[BrokenEnglish]

while fiddling around with the rail capacitance of my ppa 1.0b i also began bypassing c4 and c5 with small ceramics and fkps. the sound was quite nice until i decided to try this also with c2. after some strange experiences with my ongoing moddings of the wna rails i developed some sort of aversion to polyester caps for rail bypassing. so i decided to solder out those big 4,7µf wima mks caps in c2 and replace them with 0,082µf wima fkp (+0,022µf from the bottom side): this brought the mids back to stage again.. very nice!
maybe that's related to the way tangent recommends to use relatively small caps at c2 with the v2 (s. assembly guide) ?

 

[ppl]

Quote:

Originally Posted by BrokenEnglish while fiddling around with the rail capacitance of my ppa 1.0b i also began bypassing c4 and c5 with small ceramics and fkps. the sound was quite nice until i decided to try this also with c2. after some strange experiences with my ongoing moddings of the wna rails i developed some sort of aversion to polyester caps for rail bypassing. so i decided to solder out those big 4,7µf wima mks caps in c2 and replace them with 0,082µf wima fkp (+0,022µf from the bottom side): this brought the mids back to stage again.. very nice! maybe that's related to the way tangent recommends to use relatively small caps at c2 with the v2 (s. assembly guide) ?

i have allways like the different value cap idea as talked about prior and Tangent did not see any reason not to go that way. I belive as stated above the combo of large and small film caps are better than just one value for all C2's. I also recomend that the smaller film caps be placed so as to be between the buffer channels so thats alternate small cap big cap then small again this leaves 3 large value caps i use 0.56uF/160V Box polypropylene Film ether BC or wima MKP-10 and 0.02uF/160 Volt Wima Box MKP-4 type

 

[boodi]

sorry , I'm so noob I quite feel intrusive posting a question here....
I'm interested to know what's the current status of the ppav2 that is - what's the current best sounding setup for it .

also :
I have a ppa v1.1b and i'd like to know if overall improvement are marginals or not .
I'm very pleased with my ppa v1.1b , now running on 627/637 and probably trying some 8065 in the near future.

 

[picklgreen]

Has anyone tried different types of transistors in their buffers? Acording to the designer of the buffers for the Millet Hybrid amp, the transistors used in the glassman buffers are "slim sound, a little on the bright side. cheap and easy to source.) I have ordered some different transistors and will note my findings.

I plan to try:

MJE243/MJE253
2SC 2238 y/2SA 968 y
2SC 3422 y/2SA 1359 y

there are a couple other BD series that will work also such as the BD135-16/BD126-16 and the BD 137-16/BD 138-16.

 

[dvbjunky]

Newb question:

Can I use this buffer without any modification in other devices? I want to use it with a Digital Volume pot....input/output buffering.

 

[TzeYang]

You might want to be careful with the pot value. Since the input is BJT, it means that the input bias could be quite high, and you'll get some high dc offset when the pot is at maximum resistance.

 

[mwallace573]

Talk about a thread resurrection.

Thanks for bringing this thread back to the light, as I have a particularly burning question regarding the Glassman DB; namely where the hell can you get a set of them these days?

 

[TzeYang]

You cant.

I believe he does not produce them anymore.

Anyway, you can get almost the same thing out of Perander's QRV-05. In fact, both are extremely similar. The only difference is that Perander's buffer will have lower output transistor junction capacitance and while Glassman's buffer will have higher power output due to bigger device.

 

[mwallace573]

Quote:

Originally Posted by TzeYang /img/forum/go_quote.gif You cant. I believe he does not produce them anymore. Anyway, you can get almost the same thing out of Perander's QRV-05. In fact, both are extremely similar. The only difference is that Perander's buffer will have lower output transistor junction capacitance and while Glassman's buffer will have higher power output due to bigger device.

Interesting. The only threads I've seen that talk about the QRV-05 are in regards to Pimetas. Would these work or be made to work in an older PPA?

 

[TzeYang]

You'll have to hot wire them though. You cant use it as a direct drop in.