PSU3 and Phono3 build

[FreddieT]

Well the Pre3 has been up & running for a month now and after a couple of tweaks I have settled for now on the ECC83 for the gain stages and the 5751for the CF. I have swapped the gain stage valves a couple of times and been superficially impressed with the 5751s top end but keep returning to the ECC83 for an all round performance with better bass.

These are just bog standard Edicron branded valves and I was wondering if others might have a better top and whilst keeping the mid and lower registers of the Edicrons?

Boy is this stuff addictive!

F

[bob orbell]

So glad it's working good, GROOVE TUBE 12AX7-M if you can find two, think you may just like them. BOB

[Richard]

Hi Freddie, I'm assuming you mean Phono? If so the EI ECC83 are also my favourites of that type and I think you'll go a long way to better them.
It's certainly addictive and other ideas are fit cathode bypass caps to the first stage and, if you have version 3S, adjust the trimmer caps to better suit 5751s. As you say these may be a tad brighter if this is not done. My favourites are 5751 with bypass caps.

[bikerhifinut]

I have made a CF buffer stage using an ECC82.
I find it has good drive into the WD88VA and also works great into my old Leak Stereo20.
I am going to tidy up the wiring on it with a view to having it in my system as a permanent fixture.
Built in a hammond case from maplin, looks ok and someone with better DIY skills than me could make it look really neat.
I use my standard homebrew psu, valve rectified, regulated DC heaters. 275V Ht.

I don't know what HT you get from the WD PSU3.

I have fancied a fiddle with the 6922/ECC88 as a CF and the design on this thread looks about right to me. Exactly the same topology as my ECC82/12AU7 one, just different resistor values.



I'll try to post some pics if i can reduce the file size

Finally, I would say that my home made CF pre has no real sonic footprint, this is a good thing in my book, i don't want any extra "colour" in the sound.

Andy

[bikerhifinut]

Some pix of the homebrew.
I know its a bit of a mess, but it works.
I'm going to tart it up and putthe components on a board.
I havent used boutique parts, just ordinary carbon film resistors and the coffin jobs because that was the only ones I could lay hands on with enough powerhandling.
Caps are EVOX polyprops. ).47uF, cos thats what I had in the box!
Andy.

[bikerhifinut]

last one

[bob orbell]

Hi Andy, the WD psu3 gives 250volts under load. Your little pre looks fine and as long as you like it, that is all that matters, a bit of work now to clean up the layout should make it look very good and Im shure it will please you, by the way, what is that thing sticking out the top. BOB

[pre65]

Originally Posted by bob orbell

by the way, what is that thing sticking out the top. BOB

Phallus thermionicus.

[bob orbell]

I like that comment Philip.

[FreddieT]

Hi Richard & Bob,

Thanks for the tips

You are quiet correct I did mean the Phono3! Bob seems to favour a variant of the 12AX7 that has rocking horse dropping qualities at the moment if my short trawl on the net is anything to go by.

When you talk about EI I assume that you are referring to the Edicrons I already have. All sounds well as it is but I'm always on the look out for more.

As for cathode by pass caps in the first stage - this would give more AC gain I think and I started with 5751s to keep gain down a little to help reduce the volume control angular compression when driving my K5881. Might be worth a try with the 5751s back in place, however - any suggestions for values?

F.