New Aleph P1.7 finished last night

[bbakota2000]

Hi guys,
Here is my new Aleph P preamp. Yesterday I received the last parts, and I immediately knew that I'll have a long sleepless night of soldering, cuting, drilling and fixing. So now it's finally done. It's just a test version, because I didn't want to make a mistake like I did with my Aleph 5 (putting it all together and then screwing around with removing hum).
I pluged it in and wonderfull music started to play. The sound is really awesome. It's clear, detailed, tight and firm bass and awesome dinamics. Toroid is 150VA 2x60V, "special" mix of Dale, Riken and Caddock resistors are used, and of course Black Gates as coupling caps. 1000uf caps in PS filtering are black Elnas, and on preamp board they are Panasonics. For the testing purposes I've used 50K Alps blue pot until my balanced stepped attenuators are soldered. All of the signal wires are Cardas (even the PS wires).
But there is a problem with hum while turning the volume up. What could cause this? Any suggestions are welcome before I start desoldering and experimenting.

[bbakota2000]

PS ready to go!

[bbakota2000]

PCB

[kilowattski]

Wow! Very, very nice! I see you decided to use a pot instead of an attenuator and decided to go with a fixed gain resistor. Mine is still a few weeks away. I send the front and back panels out to Frontpanel Express to get the panels engraved. All my boards are built and just awaiting the chassis work. I also see you used Blackgate type "N" capacitors. Good Show and congratulations to you. Job well done!

[bbakota2000]

Thanks for the comments kilowattski, I hope we'll se your Aleph P soon.
I used fixed gain resistor, it's Caddock 820R 0.1%. I've just put a pot for the volume control to see if preamp is working at all. I'm waiting for Dale RN60D resistors to come so I can solder my stepped attenuators and then I hope I'll se the influence of the attenuator.
I still have a lot to do. Anodizing case, stepped attenuators, input selector with relays and I have to make it balanced.

[Anorgan]

You realy know how to make a case! Nice work.
(We realy need to have a meeting of diy-ers here in Croatia )
How much did that trany cost you, and where did you get it? And how do you obtain your "special" resistors?

[bbakota2000]

I wrote "special mix" of resistors because I've put all the leftover Rikens from Aleph 5, some new Dale resistors and two Caddocks.
Why don't we discuss it on audiofil.net forum. I'll open a new thread.

[Super_BQ]

bbakota2000,

Gee those right-angle support brackets on your chassis look very similar to mine!

http://www.geocities.com/super_bq/BLS1.html

What make is your attenuator? I'm in the market for an 8 gang stacked one for 'stepped' ladder instead of series in balanced L/R control.

BQ

[jleaman]

This looks weird no offence.. But the caps that i bought cost me like $200.oo and are way bigger.. Humm wonder what the difrence is.

but any way good job.. : O ) Keep up the good work..

[bbakota2000]

Originally posted by Super_BQ
bbakota2000,

What make is your attenuator? I'm in the market for an 8 gang stacked one for 'stepped' ladder instead of series in balanced L/R control.

BQ

It is an old ITT/Beyshlag attenuator with silver contacts. I got two of them 4 gang/25 position from my friend for free. It was used in an old military equipment and it is pretty damn good. I'll also make ladder balanced. It will be a lot of soldering.

Originally posted by JasonL
This looks weird no offence.. But the caps that i bought cost me like $200.oo and are way bigger.. Humm wonder what the difrence is.

but any way good job.. : O ) Keep up the good work..

You are probably using some "fancy" foil caps. I used Black Gates N type, and everybody who tried them said it's way better than most of the foil caps (not very expensive ones). My guess is; if you're not willing to spend $500 and more for the caps in Aleph P, Black Gate N is the only choice. These Black Gates were something like $5 a piece.