What modern substitutions would you recommend for this amp

The amp works fine Steven, no hums no nothing. Just seems like the bass is a little loose and I only noticed that with it on the D9's in the living room
 
try a different pair of speakers, one with newer woofers or see if your surrounds are a little broken down. Even more important, decrease the bass frequencies selectively with and equalizer and find the range that they work the best in...I suspect that maybe the crossovers need some attention.
 
Steven, both sets of my CV's are run on the WOPL with zero issues, surrounds are fine, crossovers are fine. Some transistors have been subbed in that maybe should not be used in this application and the others are stock from the day the amp was born. It needs a redo, it's 40 years old
 
Talked to a guy in Georgia that knows these amps. RCA-1B05 is the sub
 
Northwinds said:
Talked to a guy in Georgia that knows these amps. RCA-1B05 is the sub
Click to expand...


Ron,

I figured as much.

Phase Linear used the RCA1B05's only for a short period of time as they didn't current share too well.

Someone on this forum might have some they pulled from their Phase amp(s).

Here is a link to RCA Power Devices Data Book: https://archive.org/stream/RcaPowerDevicesDataBook1978#page/n0/mode/2up
The specs for the RCA1B05's are on pages 351, and 352.
Schematics for 100W, 200W and 300W amplifier designs appear on pages: 352-356.


Ed
 
He also explained why there is 4 trim pots on each preamp board. One is bias, one is DC offset, one is a positive limiter, last is a negative limiter

He said the 2200 is a slightly more powerful version of the 1800I and he considers it the best sounding amp of the 3 (and also the rarest) as they were used with Sensurround in theaters to supplement the BGW amplifiers when Sensurround went through 3 different iterations which later passed into history when THX Dolby took over. Like the Clair amp I have, this CV amp is a part of history. I feel lucky to own both
 
ED, I have been corresponding with AK's well regarded technician bhagstrom and he does not see any issues with putting in MJ 24/25s since the feedback circuit is not going to be messed with so there should be no oscillation issues. Also not to worry about the in rush if I up the big cans to 22,000 100V versions so what say you maybe come up and help me make this amp better when you have time in the Spring. I have to think about shielding also just in case of any EMI interference. A higher rated bridge rectifier maybe also

I wish this was just a simple deal of just screwing the new stuff in but I think testing is important to for the best results and that can only benefit your current project of getting info on the older power amps 200wpc and higher
 
If you get bored someday, I'd like to see some nice pics of the outside.
 
Bradrock said:
If you get bored someday, I'd like to see some nice pics of the outside.
Click to expand...

Pardon the dust, it's in the garage and I am not so picky about dusting out there. I have not even cleaned the amp off since I got it LMAO!!!

RmxxzXY.jpg

ssSKd9A.jpg
 
It would look better if I went and cleaned it but as a garage amp it sort of fits right in with the rest of the dusty goodies, it certainly is beefy though :laughing6:
 
Ron,

Here are some pictures of an Cerwin Vega A-2800 mono-block power amplifier I found on the internet.
The amplifier used a total of (16) GM/Delco DTS-411 transistors.

NOTE: Many are already aware that the GM/Delco DTS-411 transistors were also used by Phase Linear (in their 400's and 700 series amplifiers) and stamped XPL909. However, some not be aware that the GM/Delco DTS 411 was introduced in the spring of 1966. Around 1974, it was essentially copied by Fairchild (FT411), Motorola (MJ411), International Rectifier (IR411) and RCA (RCA411). DTS stood for Delco, Transistor, Silicon. Likewise, Delco had DTG series which was Delco, Transistor, Germanium.

I was able to find the Cerwin Vega A-2800 listed once in Audio magazines annual equipment directories. It was in the September 1973 issue on page 17. (NOTE: I have removed all the other manufacturer's on this page in the attached photo).

Rating:
700 wpc RMS at 8 ohm, .08% THD at rated power, 0.1% IM at 1 watt, 5-70kHz Freq Response at 1 watt +/-1dB, S/N ratio 110dB at rated output, Damping factor of 500, 19" x 6-1/2" x 9", 50 pounds, Price $850.00

I would love to see a schematic for this amp.
 

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  • Cerwin Vega A-2800 Front Panel.jpg
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  • Cerwin Vega A-2800 Power Supply Capacitors.jpg
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  • Cerwin Vega Audio magazine September 1973 pg 17.jpg
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FWIW, servicemanuals.net at a few other (no affiliation . . . ) claim to hqve the a-1800 service manual, but not free . . .
 
700 watts in 1973 was a pretty serious amp.

Was it for a movie theater?
 
J!m said:
700 watts in 1973 was a pretty serious amp.

Was it for a movie theater?
Click to expand...

I don't know what the original intent for the Cerwin Vega A-2800 was.

I am curious what the B+ and B- voltage rails were and if the amp was a bridge amp.
 
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