[cobaltmute]

So my Pimeta parts are on the way and I have everything I need, except of course the buffers as no-one has the BUF634P in stock. Digikey is saying mid October before arrival and Mouser is saying mid April 2009 for delivery times.

I've read that some of the alternatives are AD811AN and OPA551PA. From what I've been able to read and put together I could put any "high" current output op-amp in the position so long as on the op-amp pin 1 is not used and I tie pins 2 and 6 together.

What am I trading off by going with one of the alternatives versus holding off for the BUF634P? I tend to like a laid-back detailed type of sound and am unsure whether the buffer or op-amp will have more of an effect

And I've read that you can stack the 634s for better performance. How much of a difference does that actually make? Can you do that if you use alternative op-amps?

Any feedback would be much appreciated.

 

[Pars]

The search function is your friend, so use it.

This thread discusses Pimeta buffers a couple of years ago.

More recent threads show a new National part which if not an exact copy of a BUF634, is damn close and has the same pinout, etc. There are a couple of other parts which can be used as well, which supposedly sound better than the 634. Opamps cannot be stacked like the 634s can as they individually need their feedback resistors. Then of course their are discrete buffers such as Sijosae's, Mono's version of that (recommended), etc.

I personally don't care for the BUF634s that much so I would search out an alternative.

 

[cobaltmute]

I had found (and forgot) the thread you listed with the National buffers in it. The only problem with those is one is not in an 8 pin package and the LMH6321 is a SOIC package and not in stock at quick check. I would prefer to have DIP for flexibility and ease of soldering.

Discrete would be nice, but I'm concerned about the space as I'm trying to build my Pimeta like the tomb ones pictured here.

 

[Pars]

You will have a hard time finding anything in DIP-8 packages as the rest of the world is going to SMD. The LMH could be put on BrownDog adapters to plug into a DIP-8 socket. The Pimeta board also has SOIC pads on the backside, but I would use the browndogs personally.

The Pimeta I built with my son is setup identically to the ones you referenced by tomb, with discrete buffers (Mono) on home etched PCBs. Fits fine. It will even fit with a single to dual DIP-8 adapter (2 single opamps to a dual pinout). I have (had) DIP-8 buf634s when I built this, and compared the discretes to stacked 634s. Discrete won.

 

[MrMajestic2]

Schuro has them in stock in their ebay shop as well as the webshop:
Buffer, High Speed, ICs BUF634P, DIP-8, Burr Brown TI - eBay (item 310063059919 end time Jul-29-08 12:00:00 PDT)

Schuro - Elektronik, Lautsprecherbau, High End-Audiotechnik

I ask them this week about it, so I hope they are not lying

 

[MrMajestic2]

Oops, double post

 

[cobaltmute]

Thanks MrMajestic. I'm in Canada so shipping would hurt.

I can get the BUF634U in Canada in stock, so I could use that with Brown Dog adapters if I wanted to

I'm thinking I'm going to try the Monofied Sijosae buffer. I've just to somehow get the PCB drawing scaled to the right size so I can toner trace it.

 

[Pars]

I probably have a pdf of this at work, I'll check tomorrow. You could try PM'ing mono and see if he has a file as well.

 

[MrMajestic2]

Quote:

Originally Posted by cobaltmute /img/forum/go_quote.gif Thanks MrMajestic. I'm in Canada so shipping would hurt. I can get the BUF634U in Canada in stock, so I could use that with Brown Dog adapters if I wanted to I'm thinking I'm going to try the Monofied Sijosae buffer. I've just to somehow get the PCB drawing scaled to the right size so I can toner trace it.

Yeah, the shipping is quite expensive for just a few chips.