1950's Ampeg Amplifier

[KingCameron]

625D Schematic

Thanks Teemuk!!
I'll take all of these I can get. I need to understand what Ampeg was doing electrically with as many of their amps at this time, so I can peice together what this mystery amp is. This schematic will help.

I understand that Ampeg had several workshops, with a variety of output at this time, which makes almost every amp custom. I may have to build my own docs for this thing.

Thanks again,
Cameron

[choker]

I apologize for dredging up an ancient thread but I had been searching for info on a very similar amp and I have found some information that I wanted to share with anyone else who could benefit.

Here is the amp that I have:



This amp has 6 - 6SN7; 1 - 6SJ7; 2 - 6V6; 1 - 5Y3
The controls appear to be identical to KingCameron's mystery amp.

I have learned that my amp is a Dolphin 518 D (the "D" stands for "dual channel" --there was also a single channel version) and is a fairly close relative of the Zephyr Duette.

These were only manufactured from 1958 to 1962. Not many were made and have since become pretty rare.

Here is a schematic I have found for the preamp section. The power section was apparently the same used for several models.

[drewl]

Working on a 518D and I stumbled across this thread .

No gain from church 2 6SJ7 preamp, then I noticed pin 6 voltage way higher than plate voltage which was only about 5v.

It seems the person who rebuilt it all nice had a 470 ohm resistor to pin 6 instead of 470k ohm .

Looking at the schematic above confirmed my suspicions, and now it works great.