Apogee SA400 Power Amp

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   Hi all,

I have an old Apogee SA400 power amplifier and need to track down a service manual.  I remember being told in the past that these amps were made by Crest and are similar to the CA series but the layout looks very different and there are no PCB markings to help.

The amplifier came from Alpha Audio (now defunct), the London based hire company that was connected to comedian Jim Davidson I believe.

Any thoughts or pointers would be great.

Many thanks.

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NevilleT Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 04 May 2022 Location: Southampton Status: Offline Points: 10	Post Options Post Reply Quote NevilleT Report Post Thanks(0) Quote Reply Topic: Apogee SA400 Power Amp Posted: 21 July 2022 at 4:04pm
	Hi all, I have an old Apogee SA400 power amplifier and need to track down a service manual. I remember being told in the past that these amps were made by Crest and are similar to the CA series but the layout looks very different and there are no PCB markings to help. The amplifier came from Alpha Audio (now defunct), the London based hire company that was connected to comedian Jim Davidson I believe. Any thoughts or pointers would be great. Many thanks.

service dept Steve Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 30 January 2010 Location: S.W.London Status: Offline Points: 2034	Post Options Post Reply Quote service dept Steve Report Post Thanks(0) Quote Reply Posted: 21 July 2022 at 6:29pm
	I inherited all the manuals from Alpha Audio, I will have a look and see if I have the manual. They were based on the P series Crest amplifiers with a new front panel and a limiter/control board. It depends what you are hoping to find in the manual, iirc they were tricky controllers to set up, requiring particular loads and frequencies for calibration but there wasn't any mention of the amps because, as has been pointed out, they were largely standard crest amps, usually p4800.
	We are not "They", We are "The others"http://www.servicedept.co.uk -

NevilleT Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 04 May 2022 Location: Southampton Status: Offline Points: 10	Post Options Post Reply Quote NevilleT Report Post Thanks(0) Quote Reply Posted: 21 July 2022 at 7:01pm
	Thanks Steve, that's brilliant. I love the amplifier pictures on your site. The dust!! Thanks again, Neville

service dept Steve Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 30 January 2010 Location: S.W.London Status: Offline Points: 2034	Post Options Post Reply Quote service dept Steve Report Post Thanks(0) Quote Reply Posted: 22 July 2022 at 9:11am
	As anticipated there are no amplifier data in these manuals. The SA400 appears to be a two channel amp based on the Crest P4800 with a replacement front panel that included a set of indicator lights and washable foam filters. There is one circuit board behind the panel with the controller on it. It isn't much more than a limiter and a bit of shaping. That brings the question again, What are you hoping to find in the manual, what level are you at? For example is the amplifier belching smoke or is the HF rolling off slightly too slowly?
	We are not "They", We are "The others"http://www.servicedept.co.uk -

NevilleT Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 04 May 2022 Location: Southampton Status: Offline Points: 10	Post Options Post Reply Quote NevilleT Report Post Thanks(0) Quote Reply Posted: 22 July 2022 at 11:03am
	Hi Steve, I have o/p on both channels at peak levels of 426.5 W per Ch befor clipping. But measured at the speaker o/p on one channel I have a DC offset of 11.3V (unloaded). I notice a trimmer pot on the daughter board of one of the amp modules, but the one with the offset is mounted flipped upside down so the pot is not accessable without pulling the module. I thought I'd try and get the SM to find out the proper test points for the measuring the offset and where to adjust rather than just blunder on..

service dept Steve Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 30 January 2010 Location: S.W.London Status: Offline Points: 2034	Post Options Post Reply Quote service dept Steve Report Post Thanks(0) Quote Reply Posted: 22 July 2022 at 12:47pm
	11v3 at the output is obviously a fault condition, I'm surprised the protect circuit doesn't engage at that sort of voltage, You might have a double failure. The trim pot won't help as that is the bias adjust not an offset adjustment, you will need to locate and clear the fault on the module before proceeding. The apogee manuals don't cover the amplifiers, you'll need to use a crest P4800 manual. Assuming of course that your needs don't exceed your skills.
	We are not "They", We are "The others"http://www.servicedept.co.uk -