good day all I hope all are safe and in good health So I picked up an Adcom GFP-565 should have it in my possession in about 10 days so I'm looking for any info on mods other then the obvious replace the Electrolytics are there any others mods maybe some opamp upgrades or anything else I can do to make this baby really sing Thank You Stay Safe
You have a problem---- according to the company the op-amps are --in-house specialized versions and are hardwired to the circuit board .
I don't see much in the way of complaints about this pre-amp other than "its old " which doesn't amount to a hill of beans,as a matter of fact the phono section has been praised by several audio enthusiasts.
Replacing the electrolytic,s is probably a wise move ,others may advise more work on it but to me its not a bad pre-amp.
gfp565.gif (GIF Image, 3509 × 2480 pixels)
I don't see much in the way of complaints about this pre-amp other than "its old " which doesn't amount to a hill of beans,as a matter of fact the phono section has been praised by several audio enthusiasts.
Replacing the electrolytic,s is probably a wise move ,others may advise more work on it but to me its not a bad pre-amp.
gfp565.gif (GIF Image, 3509 × 2480 pixels)
thanks duncan2 from what I have been reading i'm coming to the same conclusion there are some diyer's installing some sockets and replacing the opamps with some monstrosities of opamps that well not for me I will give it a good listen thought about doing a head to head with my Kenwood Basic C2 and see which sounds better to this set of old ears of mine maybe even write up the results of the head to head seems others are curious of the result anyways TO BE CONTINUED
Gary Galo wrote up an extensive article on the GFP565 in AudioXpress decades ago. I have two GFP565's -- The major issue with the GFP-565 is the power transformer which is a bit under-rated. Mine uses an external supply with a beefier Avemco transformer AND Jung Super-Regulators.
The operational amplifier chips are Linear Tech -- LT1057, the driver chip is an LT1010 -- in mine this was replaced with a composite driver using BUF634. (You can't directly substitute the BUF634 as the pinout differs.) And of course, there is a new and improved BUF634A.
RIAA is +/- 0.1dB from 20Hz to 20kHz.
The operational amplifier chips are Linear Tech -- LT1057, the driver chip is an LT1010 -- in mine this was replaced with a composite driver using BUF634. (You can't directly substitute the BUF634 as the pinout differs.) And of course, there is a new and improved BUF634A.
RIAA is +/- 0.1dB from 20Hz to 20kHz.
The grass is always greener on the other side ---ask D.Self why he uses 5534,s .
quote-
In Jan Didden's "Linear Audio" publication a few issues ago, Doug Self still defends his use of the venerable 5534s and series electrolytic caps in his older preamp/mixer design that many of us see with amazement - who knows, without building the circuit, just how well they actually work in particular situations.
stereo.net.au
quote-
In Jan Didden's "Linear Audio" publication a few issues ago, Doug Self still defends his use of the venerable 5534s and series electrolytic caps in his older preamp/mixer design that many of us see with amazement - who knows, without building the circuit, just how well they actually work in particular situations.
stereo.net.au
That's what I am using (NE5534) in my hotted-up Crown IC-150.
The new issue devices from TI are excellent.