speaker out - line out circuit question

[ioaudio]

from an old dual vinyl player :

what would i have to do to change the 5 Ohm speaker out to a 4dbU line out?

i would like to use this circuit as a summing amp with unbalanced inputs.

lowering the current for the single ended stage? (any use for the existing output transformator)

or changing the output stage completly ?
i could use two sowter 3603, i have laying around.
http://www.sowter.co.uk/specs/3603.htm

sorry for my little understanding...
thanks for any suggestions!

 

[PRR]

Man, what a lot of EQ circuits for a 2-tube plattenspieler.

> use this circuit as a summing amp with unbalanced inputs.

Yeah, you could do that....

> what would i have to do

The output transformer will deliver +14dBu at unknown frequency response/distortion. +14 is not enough headroom for good speech/music at "+4" nominal level. If you relax your output spec a few dB, and slam feedback around it, you might do OK.

Otherwise you are looking for something like 5K or 10K to 150Ω at 40mA, which is a fairly unusual winding.... you find these by stripping perfectly good ProAudio line amps, and it makes no sense to cut-up a good line-amp for parts to modify a consumer record player into a line-amp.

Also I would assume that all electrolytics are old and have gone bad.

Also I bet you'll want to re-wire the heaters balanced and twisted.

So all that is left is a scrap of metal with power transformer, choke, and two sockets.

It might be a killer low-Z headphone amp.

 

[ioaudio]

thanks a lot for making things so clear!

i did in fact use it as a (very loud) headphone amp, a little noisy, but replacing the electrolytics and rewire the heating like suggested might help here. maybe you have some advice for canceling the eq completely for this application?

for use as a summing amp i recently found this circuit using the ecl 86,its a (transformerless)hifi preamp (german site)

http://www.jogis-roehrenbude.de/Verstaerker/ECL86-VV.htm

 

[ioaudio]

ok, i thought about it. i dont want to build crap, i´m going for a g9.
maybe i can use the power supply.