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Old 27th March 2014, 08:24 PM   #1
B00B00 is offline B00B00  Canada
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Default Armaco TTHF or Calrad AP 15 What to do What to do?...

So I had a little time this afternoon and was listening and comparing the merits of a SS Cambridge Azur A540a v2 vs an Armaco TTHF (which is the same as a Calrad ap-15)

There isn't a lot of information on the net about these. In a nutshell: Dual monoblocs, made in Japan I believe... Integrated amp built in 1961, push-pull configuration and has a single 12AX7, two 6BM8s and a 6CA4 rectifier.
Click the image to open in full size.

The Cambridge is more precise, it images better (both in width and depth) has more air between the instruments. Cleaner (you can hear further into the recording) However it is thinner and even though it has 60 wpc you'd swear it was less powerful than the 15wpc Armacos...

The Armacos feel like they go an octave lower... even though they hum a bit and the bass is a little wooly, the sound is *liquid*... It feels like a warm blanket or the voice of an old friend. A fuller, rounder sound, an electric guitar sounds like it should and the amplifier has more attack. Notes come forth with authority. For a 53 year old amplifier, it acquits itself remarkably well. Actually, it has no business sounding this good.

Fully restored, I'm thinking it could be magical. The electrolytics inside are a good 35-40 years past their prime...

The Armacos are wonderful. That being said, I'm not ready to give up the air, the detail and the imaging of the Cambridge; on some recordings it sounds really good, the Armacos seem to be less recording dependant.

Time to look at restoring the Armaco I think....

OR...

Have it modified to SE topology?

Something else?

I have 97 db efficient speakers so I don't need a lot of grunt and don't mind giving up a few watts for some magic... That being said the Armaco TTHFs drove them with more authority than a Sophia Baby Electric I had for a bit.

I have a little experience with circuits and know enough that I shouldn't be rooting around there without someone more experienced looking over my shoulder. I have a few (experienced) friends that could help me out. So replacing a few caps would be a possibility but more than that... I'm not so sure.

I want to keep these as I like what I hear but want more detail, imaging and air (at present the top end definitely feels rolled off as well)

As far as I know, they weren't anything *super-special* so I wouldn't mind modifying the chassis in order to see those lovely valves... Right now, they are hidden behind sheetmetal.

I don't really want to restore them, only to decide... meh that wasn't what I was looking for exactly.(But I guess that's part of the game.)

There was a gentleman I might consider sending them to (I think in the NE US who builds and modifies tube amps that comes highly recommended. I stumbled upon his web page but now can't for the life of me remember his name. That's what you get for staying up late at night and reading) There was a written piece about how his mentor had bought a bunch of parts out of a basement and had tried a whole bunch of topologies and figured out what worked and what didn't. The gentleman in question had Dynaco st70's, a hammond organ amp that he had modified and many other curiosities and wonderful amplifiers on his website (purple background I think). Anyone know who I'm talking about?

Apart from that, any suggestions?

Thank you,
-andre-
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