Suggestions on Balanced Line Stage - parts?

[lgreen]

Hello, I am starting my 1st project in about 15 years, a preamp.

I was thinking of building the Pass "Balanced Line Stage" and making my own PCB to boot (using eagle pcb).

I have looked extensively though this forum and seen a lot of nice examples. My question is where do I get the parts and what parts do you all reccommend? I have looked throughout the web, digikey, etc... so kind of know where to get parts. The question is which parts?

To think about getting started, I need to figure out the major parts that I probably won't want to change which are:

1. AC transformer (I want a toroid)
2. gain transistors (IRF 610 or something else? are these current?)
3. volume control POT (balanced) what R values work well?
4. Selector switch
5. Balance control POT (I may want one)?
6. PS diodes, rectifiers, etc..

So this may be a bit of an unfair post, I don't want you all to design this thing for me, but if you found a great part for this project, can you share the link on how to get it?

- thanks

 

[moe29]

Hey lgreen,

I purchased the parts as listed in the article from
Digi-Key. The IRF610's are fine. I used the bridge rectifiers from
the parts list. Transformers from Avel-Lindberg, Plitron,
Victoria Magnetics, etc. seem to be used a lot on the forum.

The Volume Control issue seems to be just that! I went with the
pots from the parts list once again. It's a little tricky adjusting
the volume (2 mono pots for each channel) but it's not that bad.
I still haven't put my baby in a finished chasis yet, mostly
because i'm still trying to finalize the layout. It's such a versitle
pre-amp, and i'd like to keep all options (P1-5) in the final box.

have fun

m.

 

[grataku]

Do you plan to use the preamp se or bal?

You probably should buy all the parts and then make the pcb.
Things get really HOT, especially the 750 ohms resistors which you have no way of cooling, and the mosfets, especially the regulator. You may have to design around the caps since audiophile grade caps can be rather large.
I ended up using thick film resistors to220 from digikey and I mounted them o heatsink. They could be ohmite I am not sure, they only have that one kind. You could use MILLS MRA-5.
One thing I would recommend if using reg. resistors is NOT to push them in all the way agaist the PCB but to let them 'breathe'.
Admittedly, I have developed a 'fixation' for non inductive ww resistors over the regular metal film but IMHO the latter are too weak for this application.

You may want to split the PS into a real dual mono, dual rectifier with nice schottky or soft recovery diodes (see other threads).

I use a pair of dual black beauty 10k pots, they are dented so finding the balance is not a big deal. If you want to go with the ultimate in input selection and volume control I have I word for you: APOX!

 

[Dane]

I purchased my Semiconductors from DigiKey, and the Dale metal film resistors from Mouser.
For volume control I will be using the APOX kit.
The Toroid transformer from Avel Lindberg is on the way,
and I just soldered in some MSR860 diodes from Newark for the rectifers in the dual power supplies.
Since I'm building the P1.7, and since it has 16 10uF film coupling capacitors,
I am going to start with Panasonic and get the thing working!