[pddjsteve]

Quote:

Originally Posted by luvdunhill pddjsteve: I just checked out BatchPCB's website, and one you're done with the Eagle files, I'd probably take the lead and try to order a couple from BatchPCB if you could post the Eagle files... seems the design is pretty much worked out to me at least. -Marc

I have been thinking about making some too, thanks to my recent run of horrible luck etching my own (the first were perfect, but accidentally mirrored; the second were on the right side but came out crappy). The latest version of the adapter is about 16mm x 12mm, so with their prices even making just 3 could end up being about $17 plus shipping. I was looking at Olimex and their single side prototype is $26 + $9 shipping for a 160mm x 100mm panel. So theoretically, I could get a whole bunch of them made for $35.

Quote:

Originally Posted by Pars I'd check Digikey under the MillMax pin receptacles and P.C. pins section. I've used some of the right angle ones for some Schottky bridge PCBs I did (pn. ED5058-ND) before and they worked great. You might be able to pull pins from a machined-pin DIP socket and use those also.

I think the easiest and cheapest thing is to remove the pins from a dip8 socket. It isn't too hard - I put the socket upside down on a peice of cardboard, grabbed the pin with a pair of needle nose pliers right where it widens, and pushed down.

I sized the holes on the adapter for the pins in the mill-max low profile socket that was on one of Tangent's parts reccomendation pages. I also have a 64-pin breakaway sip strip made by mill-max, it is the same pins. Mouser part number for the sip strip is 575-113164.



Also, here is an SMD version. I could even make it 2 sided and make it a 2 intersil to 1 buf634 adapter:

Schematic and board files for both the dip and soic versions are here.

 

[applegd]

I use ALPS RK27 in my PIMETA, so there is no room for the discrete diamond buffer board below.

I think if the diamond buffer board above uses SMD parts, it should be able to fit in..

 

[kklee]

Quote:

Originally Posted by applegd I use ALPS RK27 in my PIMETA, so there is no room for the discrete diamond buffer board below.

This Pimeta actually started out with a RK27, but I replaced it with a RK097 to make room for the DB's.

 

[applegd]

Quote:

Originally Posted by tomb I said it. They sounded much better than BUF634's stacked, but it was on a Millett. So, the experience is probably not applicable.

Now I have HA5002(SO8)x2/channel(tiny board push into BUF634 socket directly in my PIMETA) for R and L, for G I still use BUF634x1. The sound improved a lot(to me) especially the treble, bass is tighter too.

If I recall correctly, the HA5002 chip uses diamond buffer design, suppose the IC should provide much better component match between 2 ICs(for R and L respectively). As I am not sure how much improvement discrete diamond buffer can provide over HA5002, so I stick to current HA5002x2/channel as of now. I might upgrade G channal to HA5002x2 later.

 

[tomb]

Quote:

Originally Posted by applegd Now I have HA5002(SO8)x2/channel(tiny board push into BUF634 socket directly in my PIMETA) for R and L, for G I still use BUF634x1. The sound improved a lot(to me) especially the treble, bass is tighter too. If I recall correctly, the HA5002 chip uses diamond buffer design, suppose the IC should provide much better component match between 2 ICs(for R and L respectively). As I am not sure how much improvement discrete diamond buffer can provide over HA5002, so I stick to current HA5002x2/channel as of now. I might upgrade G channal to HA5002x2 later.

That's great news. In the latest posts traded with Amb, he defined the original concern with stacking as a chance that the output stage of one Intersil might drive the other buffer (in a stack) instead of the load. The PPA designers refered to it as "ringing". Because of the configuration, compensating for this tendency would prevent stacking. Maybe that's why it hasn't been tried very often (if at all).

Your experience parallels mine (sorry for the pun), in that stacking the Intersils has no ill effects except improving the sound in every way - noticeably better than stacked BUF634's, as you confirm.

Amb did say we were in "uncharted waters" with this tweak, so maybe we've discovered something heretofore not considered with conventional wisdom. I've received some more Intersils in the meantime and am going to try them on the SOHA and maybe my PIMETA's, too.


P.S. Stacking the Intersils decreases their short-circuit potential, too.

 

[pddjsteve]

Has anyone tried paralleling the LMH6321 yet?

 

[Andrea]

Quote:

Originally Posted by pddjsteve Has anyone tried paralleling the LMH6321 yet?

Why? More than 300 mA of output current (in a Pimeta) would seem pointless to me.

 

[quicksilver96]

And more than the 250 you get from paralleling (stacking) widband buf634s isn't?

This is head-fi

, most of what we do doesn't seem necessary and power inefficiency is the name of the game.

I have some lmh6321s, but the pimeta is currently in pieces while the case gets a refinish. Someone take one for the team!!

 

[pddjsteve]

Why? Why not?

I just figured that since paralleling the other buffers led to improvements in the sound, and the LMH sounds great to me, maybe it could be even better. I've got 3 mounted on browndogs that are going to go in my pimeta, and if I had some more I'd give it a shot. I could solder them right to the board, but I want to roll buffers as well as opamps.

 

[Andrea]

Yes, this is head-fi

, but... with the other two buffers it happens to make sense: the HA-5002 seems to have a sub par performance on low impedances; and the BUF634 not-so-outstanding dynamics & transparency.

If, as they say, the LMH6321 sounds great, has great transparency, and has better low end dynamics than the BUF634... I wouldn't bother with paralleling, I think. I guess I'll have to try the LMH buffers soon

 

[applegd]

Quote:

Originally Posted by Andrea Yes, this is head-fi , but... with the other two buffers it happens to make sense: the HA-5002 seems to have a sub par performance on low impedances; and the BUF634 not-so-outstanding dynamics & transparency.

I am using HD650 with my PIMETA, so HA-5002's sub par performance on low impedances does not bother me.

I am ordering ten more HA5002 to make HA5002x4 for L,R channel, HA5002x2 for G channel.

 

[pddjsteve]

The mouser order finally arrived today, and I'm just about finished debugging my pimeta. I've got LMH6321 in for the buffers, and right now have a 2227/227 for opamps until I get it working. I think all I have to do is get the output jack rewired (accidentally snapped off the left channel wire, grr!) and then it will be done except for casework. Once it gets some burn-in time, I'll play around swapping opamp.

 

[Andrea]

Quote:

Originally Posted by applegd I am using HD650 with my PIMETA, so HA-5002's sub par performance on low impedances does not bother me. I am ordering ten more HA5002 to make HA5002x4 for L,R channel, HA5002x2 for G channel.

It's a Headroom's recent finding, that's why they switched to Diamond buffers for all of their amps. Although "they don't sound nearly as bad as they measure".

And btw, I also really like the (single) HA-5002, on low impedances, too.

 

[applegd]

Now my PIMETA has OPA637(for L/R), OPA627(for G) as Opamp. On buffer side, HA5002x4 for R/L, HA5002x2 for G. I am satisfied with its sounding.

Will try SMD version of discrete damond buffer if I can find it........

 

[tomb]

HA-5002 x4? Wow! Is that stacked?