Creek 4330 ...curious power inside

[redrabbit]

I opened up my 4330r integrated amp today, to possibly add a DIY MM phono stage in there.

The pins meant for the add-on phono card state: +25v.
...but my meter is saying those pins are +34.5v
The DC side of the power rectifiers also reads +34.5v
(the main filter caps inside are rated for 35v )

Is this the normal voltage ?....and the phono card should have it's own regulation ?

I don't have a schematic.


=RR=

[redrabbit]

what I found, from the Epos Creek forum

(poster) Mike Creek:

....In all the Creek Phono stages, both internal and external, we use an LM317 adjustable voltage regulator to stabilise the power supply, on-board.....

So, the power at the pins in not strange, the voltage printed on the board is in regards to the regulator on the add-on board.

So if I add a DIY phono-pre circuit in there, I can regulate it to any voltage I choose, bearing in mind the heat dissipated from the regulator if I ratchet it down too much. Best to stay near 24v.

=FB=

[AndrewT]

Hi,
like to try an experiment?
Connect a 2W 4k7 resistor between the + &- 34.5Vdc supplies and read off the voltage under load.

A discrete pre running from +-24Vdc will potentially have a maximum output of 16Vac. This would be an exemplary target for adequate overhead.

[redrabbit]

Originally posted by AndrewT
Hi,
like to try an experiment?
Connect a 2W 4k7 resistor between the + &- 34.5Vdc supplies and read off the voltage under load.

I'm guessing that would give me lower, around 25v or so ??

....but....I think the power amp circuitry is already acting like a load, no? ......am I missing something?

I know from building a CRC power supply, it will measure higher with no load, lower (the target voltage) with a load.

I don't know if this Creek power amp section uses any regulation, other than cap filtering.

(btw, I changed the Creek's stock (6) 3300uf 35v filter caps to (10) 2200uf 50v panasonic FC's) ...(conveniently, there were empty unused holes/pads already on the main board)

=RR=