Anyone familiar with these amps?

SteveG · Aug 31, 2004

Hi,

What a great forum, nice to see there are others out there even more obsessive than I am!

Anyway, I just bought this pair on Ebay. (http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=3284&item=5717990013&rd=1) Not much of a description, and probably at least a little inaccurate. I'm guessing that they are part of the electronics from a tape machine?

Any help with identification/info would be much appreciated.

Cheers

Steve

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PRR · Sep 1, 2004

> I'm guessing that they are part of the electronics from a tape machine?

Yes. A Crown tape machine. Where were you in 1972? I guess you missed that era. (The 1972 Crown was all transistor with RTL logic; these must be older.)

> probably at least a little inaccurate.

They appear to be missing the mike input transformers. (Round black socket rear top left.) Many of these decks were used Line Input Only, proper mike inputs were optional. If there are jumpers in the transformer socket, it may work as a modest-gain UNbalanced mike amp.

On one hand, I think you paid a lot for a fairly uninspired box without a critical piece needed to use it as you intended (mike amp). On the other hand, it is a heck of a box and a monster meter: looks really good in the rack. I have four or six channels of the transistor version; I wonder what they are worth?

Jensen or Sowter can sell you a fine 1:7 or 1:10 mike input transformer, and the connections will be fairly obvious when you open the chassis.

I also don't see any evidence of an output transformer, so it may not be balanced low-Z output.

The Phones jack will only like high impedance phones, possibly 2K which rules out most modern phones.

Expect to have to clean the switches (or just solder around the Source Tape switch to leave it stuck in Source; I don't think the other switches do you any good without the deck).

Crown is certainly still in business. Call them and sweet-talk yourself a manual. Crown had EXCELLENT manuals in those days.

SteveG · Sep 1, 2004

Cheers for the replies.

I've already started to gather together the bits for two LA2A's, so these might well end up as just that, or more likely some great mic pre-amps.

Steve

PRR · Sep 2, 2004

The Crown tape deck those modules came from is probably in this picture:

I've just dredged Crown's website and they mention their tape heritage only in passing, no details nor manuals. Still a fair chance that if you call, and talk nice, they can make a copy of the service manual for nominal fee.

SteveG · Sep 2, 2004

Wow, thats a lot of tape machines!

It occurs to me that not much thought seems to be given to the last stage of amplification (and modulation) in the signal chain before the signal reaches the record head. I guess that's not because the process isn't important to the final sound, but because the devices are usually hidden inside the tape machine, and easilly forgotten about.

I'm looking forward to sketching the circuit diagram when the Crown amps arrive.

Steve