Making changes to PSU II

[bikerhifinut]

Most of you will know that I rate the Aikido CF highly.
I built mine around the ECC82, not my favourite valve for audio but in a cathode follower i think it has strengths. What I noticed in particular was how brand "agnostic" the aikido CF seems to be. The sound presentation didnt seem to alter between el cheapo Edicrons I have or fancy box plate Mullards and various in between. This I feel is a vindication of John Broskie's Ethos in the Aikido design using an individual valve's non-linearity against itself to bring it back into line. I also felt I got the best result with a regulated PSU.
Now I have a set of parts to build a Pre3 and with the larger WD preamp case that Greg sold me (), I've a notion to build it using 6SN7 valves rather than ECC82. I have a few ideas also to knock the overall gain down without using external negative feedback. The reason is that when we move house in the next month or so, I'll be organising my system so that my monoblocs are behind/beside the speakers and fed from the preamp by a long signal wire. I have a feeling the very low impedance drive from a transformer fed by the grunt from high-ish current valves (ECC82 or variants) will be ideal for this and hopefully i won't need to spend money on fancy low capacitance wire. In fact I have a long term desire to use the balanced output from the transformers into a modded pair of monoblocs. i.e. I won't need to build a push pull amp with a phase splitter, just driver valves to the output valves.
That'll keep me busy for a year or 3!

Andy.

[Greg.]

Originally Posted by bikerhifinut

Now I have a set of parts to build a Pre3 and with the larger WD preamp case that Greg sold me (),

Andy.

It wasn't me who sold it to you but rather, Nigel who masquerades as vinylspinner. I was just there when you made the exchange.

The large or double size pre-amp case you bought was a prototype that Peter Comeau was thinking about using when he was the owner of WD.

It seems there are several WD owners who appreciate the benefits of the John Brosky Aikido cathode follower kit.

Food for thought, me thinks, eh Matthew?

[bob orbell]

Yes, it would be nice if Matthew could do a similar kit, but what I think would be more beneficial, is a regulated PSU, I am playing with HT regulators in my two PSU's at the moment, had a few explosions of the transistors, but when working, the sound is so much more natural, and the voltage is rock steady. My PRE has been modded to a CF with active load and is also very good, I did make a lash up of an Akidio, and a White CF, but the CF with aktive load is winning. BOB

[colin.hepburn]

Hi BOB/All
Interesting regulated PSU what schematic are you trying is this of any use to you I got this from nick of audio talk some years ago see image I may try this my self

[bikerhifinut]

Originally Posted by Greg.

It wasn't me who sold it to you but rather, Nigel who masquerades as vinylspinner. I was just there when you made the exchange.

The large or double size pre-amp case you bought was a prototype that Peter Comeau was thinking about using when he was the owner of WD.

It seems there are several WD owners who appreciate the benefits of the John Brosky Aikido cathode follower kit.

Food for thought, me thinks, eh Matthew?

Sorry Greg, senior moment. Apologies to both you and Nigel. Yes I was aware of the cases pedigree.

A.

[bikerhifinut]

Originally Posted by bob orbell

Yes, it would be nice if Matthew could do a similar kit, but what I think would be more beneficial, is a regulated PSU, I am playing with HT regulators in my two PSU's at the moment, had a few explosions of the transistors, but when working, the sound is so much more natural, and the voltage is rock steady. My PRE has been modded to a CF with active load and is also very good, I did make a lash up of an Akidio, and a White CF, but the CF with aktive load is winning. BOB

There's really not a mega load of difference between the aikido and that active load circuit in the MJ book. Looking at it theres the potential divider off the HT rail coupled to the grid of the load valve so that fluctuations in the Ht voltage are fed to the grid which is meant to compensate. bad description I know but that's sort of how i remember the description.

FWIW I think the regulated PSU has less advantage in this sort of line stage than in say a RIAA preamp. It's handy if like me your mains supply is all over the place and often pushing 255V which is awful high.

A.

[bob orbell]

That looks a very simple reg. Colin, I started off using two MPSA92 transistors, but something was wrong, they kept going bang, so I moved on to LM317 and support circuitry using two NSD 134, it works but looks a mess at the moment. Can you somehow blow that circuit up, as I can see very little, it looks so simple. BOB

[colin.hepburn]

Originally Posted by bob orbell

That looks a very simple reg. Colin, I started off using two MPSA92 transistors, but something was wrong, they kept going bang, so I moved on to LM317 and support circuitry using two NSD 134, it works but looks a mess at the moment. Can you somehow blow that circuit up, as I can see very little, it looks so simple. BOB

Hi BOB
are you using foxit pdf should be the same in adobe pdf
just click visible tag or increases page size to 300%

[pre65]

I hate Adobe PDF reader and much prefer Foxit.(and it's still free)

It downloads OK for me and then expand to fit the screen.

[bob orbell]

Originally Posted by colin.hepburn

Hi BOB/All
Interesting regulated PSU what schematic are you trying is this of any use to you I got this from nick of audio talk some years ago see image I may try this my self

Thank's Colin, I managed to blow it up to a good size, I could not quite see what the two circular devises were, now I can, they are VR tubes, but looking at this, you may just as well use a string of Zener diodes insted of the transistors and VR diodes me thinks, or is this circuit better than say four 52 volt Zeners?. BOB