[Gojira]

Could anyone let me know how to find the .05% resistors and special 5uF caps for the Gilmore V2 amp? I can't seem to find any at Digikey, Mouser, or MCM.

Also, where is the volume pot in the amplifier section V2 schematic. I can't find it, but I assume it must have one. There's definitely no symbol for one in the schematic though. Could it be a fixed volume

?

In addition, I see what looks like a full wave rectifier worth of diodes after the transformers but they are not very specified, just "100v/2A". Any suggestions? on actual parts? (INx00x or whatever)

I apologize if these questions have been asked before but I couldn't find them if they were.

Edit: I found the Pana E1475-ND metallized poly caps at Digikey. At $2.72 ea or $2.33 ea. for 10 they'll be some of the more expensive caps I've bought, but they seem ok. I noticed that they x-ref with some Wimas. I wonder how close they are. What's so bad about polyester?

 

[Arzela]

Hi, I inquired about the caps some time ago.
This was in February I think. The caps were
not available then. Illinois Cap required
a minimum order of 50 pieces at 8 bucks a piece
with a six week lead time.

Perhaps one of thier distributors has them now. Check out thier web page.

The web page is www.illinoiscapacitor.com

The part number is 505phc850k

The pot should go between the inputs and source.

Oh...Mouser sells .05% 10 k resistors

http://www.mouser.com/index.cfm?hand...oductid=300359

 

[Gojira]

Thanks for the quick reply Arzela (this place is great). I'm looking at the page now. Wow! Metallized Polypropylene! How exotic. I don't think I've ever seen that before. 800V seems a bit excessive though. Can't we just get 5 or 10 people together for a min order? With more than 6000 members at Head-fi, it doesn't seem like it should be too difficult to get like 10 people together. Or even 5 would be cool with me. Although the Digikey Panasonics are only $2.33 each. Do you think the difference would be noticeable?

Also, what about the resistors. Did you come up with any good sources for those. Never heard of 22.8k .05% resistors. Pretty weird. 22.6k I can find. 0.1% I can find. But not 22.8k.

Would a 100k pot work for a volume control? I'd like to try using one of those fake Alps (Cixi Zhenwei) pots.

I assume that the inputs (where the actual miniplug or dual rca jacks would wire to) is labeled "-I" and "+I" (and ground). I don't want to sound too stupid here, but the "I" stands for "Input" I assume. Believe it or not this will not be my first electronic project

I just usually have easier to read schematics. Actually the schematic itself looks pretty simple (at least the amp section). Probably deceptive though. Also it's been awhile.

I can't quite follow the section where the transformers meet the rectifier diodes, but I think I'll be able to figure it out.

I'm going to build a Jung multiloop amp first, but I want to order all the parts at once.

I have a pretty good system for making my own PC boards (one of those toner transfer systems), but maybe this kind of project would be better wired up on perf (as much as I hate the sloppiness of that). My previous experience has always been with very compact, very low current circuits without any need for a ground plane or thick conductors or anything. I'd be a bit concerned about the thickness of the copper traces vs jumper wire. Did you ever finalize a PCB layout? That's always a bit of a PITA. Maybe I should just use yours instead of doing my own

.

Do you have a good source for epoxy PCB with a nice thick copper cladding?

Edit: This is like a chat. Thanks for the answer on the resistors.

 

[Arzela]

Hi,

Quote:

Thanks for the quick reply Arzela (this place is great). I'm looking at the page now. Wow! Metallized Polypropylene! How exotic. I don't think I've ever seen that before. 800V seems a bit excessive though. Can't we just get 5 or 10 people together for a min order? With more than 6000 members at Head-fi, it doesn't seem like it should be too difficult to get like 10 people together. Or even 5 would be cool with me. Although the Digikey Panasonics are only $2.33 each. Do you think the difference would be noticeable?

I tried to get a group order going
earlier. I think I had five people interested. I can bump the post, or repost a new one
and see how things go.

I've not succesfully had caps that work
in this position. The IC's are the original specified
cap, and thier inductance is far lower
than any cap i've seen. Thier slew rate is far greater
than any cap I've seen. SO I think
they are the way to go....

on the other hand the Pans. might be adequate (I've yet to try them)

Quote:

Pretty weird. 22.6k I can find. 0.1% I can find. But not 22.8k.

I use the 22.6k. These work fine, but give an output
voltage of 22.32 V. I guess a trimmer pot
could be used....
i bought all my res. (rn60C dales, mostly .1%) from Mouser
A lot of these were not exact: 3.32k for 3.3K, 499 for 500, 511 for 510, 24.9 for 25, 4.99k for 5k.

Quote:

Would a 100k pot work for a volume control? I'd like to try using one of those fake Alps (Cixi Zhenwei) pots.

I would guess 100k is all right. I use a 50k Alps Black Beuty, it sounds great. What
does Antness use in the V2?



Quote:

Did you ever finalize a PCB layout? That's always a bit of a PITA. Maybe I should just use yours instead of doing my own

Yes, my boards come in Friday. I'll
let you know how they turn out.

I also have a layout for the power supply, I could post this if you like..

With regards to the PCB boards:
The Digi-key Injectorall Electronics boards are nice and not
too expensive..
1 oz copper I think, but it's available in 2oz (and double sided 4oz)
Part number PC7-ND 6x9, 1 oz. $9.30
Part number PC11-ND 6x9, 2oz. $9.95
PC81-ND. Doublesided 4oz, 6x9. $15.11


Quote:

I assume that the inputs (where the actual miniplug or dual rca jacks would wire to) is labeled "-I" and "+I" (and ground). ... the "I" stands for "Input" I assume.

Almost, I+ is for input. I- ties in
to 1k and 10k resistors (see the schematic for
the servo).



Sorry for all the edits. Last one!

 

[Gojira]

I tried to get a group order going
earlier. I think I had five people interested. I can bump the post, or repost a new one
and see how things go.

Sounds good to me.

I've not succesfully had caps that work
in this position.

What do you mean? What position?

on the other hand the Pans. might be adequate (I've yet to try them)

Did you just leave out the caps? What have you tried?

I would guess 100k is all right. I use a 50k Alps Black Beuty, it sounds great.

Did you find a good source for the Black Beauty?

Yes, my boards come in Friday. I'll
let you know how they turn out.

Are you etching them yourself? What's your method?
Are you going with double or single sided?

I also have a layout for the power supply, I could post this if you like..

That would be great.

I was just looking over the servo schematic and I realized that I just don't understand it completely or how it integrates into the main schematic. Although most of the parts and connections are well specified in Gilmore's document, some of it does seem slightly vague, just enough so that you have to understand the circuit design itself to put the pieces together.

It looks like those two "DC adjust" points in the main schematic connect to a 15k resistor, which then connects to the output pin of an Analog Devices OP27 opamp. I'd like to redraw the schematic to integrate the servo schematic into the main one. As it is I think I understand it but I'm not sure. Perhaps I could redraw the schematic integrated with the servo circuit and post it to see if I've got it right.

Do you know of any good software for drawing schematics?

 

[Arzela]

Quote:

What do you mean? What position?

The 5 uf caps in the power supply.
Sorry for the ambiguity.

Quote:

Did you just leave out the caps? What have you tried?

I've left the 5 uf caps out for
the momment. I've tried
Axon/Solen and some other caps
I found locally. Others have
reported problems with Wima...

The Axon works nicely for the 5uf
caps tied to +- 24 v. The caps
tied to +- 16v is what gives
me trouble (overheating, oscillation).
I'll try the Panasonics here and report.


Check out this thread for suggestions on taming this problem with bypass caps:
http://www4.head-fi.org/forums/showt...ower+capacitor

Quote:

Did you find a good source for the Black Beauty?

www.percyaudio.com

I've had very good repsonse time
with Mr. Percy. They are a bit pricy, $35, but they are nice pots. He sells
them in detented and non-detented versions.

Quote:

Are you etching them yourself? What's your method?

I had them professionally made by pcb123.com. Here's the layout:

http://www4.head-fi.org/forums/showt...lmore+balanced

Here's a link to the power supply
layout:

Power layout

This layout uses the parts specified for the Headamp v1 (In particular: Talema tranny DigiKey TE70074, Bridge rectifier: Digikey KEL01,
trimmer Bourns 3299 (?) Mouser652-3299Y-1-203). I put in extra room around the voltage regulators and 548's for bigger heatsinks.

Note that two wires must be mounted above board to connect the V+ and V- supply pins
of the opa548's.

There are pads for the 5uf caps tied to the 24 volt rails. I did not provide
pads for the other 5 uf caps, but these could easily be drawn in.

One sided.

Board size: 7.575 x 4.448 inches.

If you have trouble printing this out correctly, let me know...

You should also search for posts by Boyelroy, he has some nice layouts for the power supply.


I like your idea for the schematic. Sorry, but I've never used a schematic drawing program. Your observation about
the 7.5k's tying to a 15 k is correct, though.


EDIT: My power layout is now in black and white.