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Old 30th April 2012, 01:17 AM   #81
kevinkr is offline kevinkr  United States
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Widerangesound, those amps look great, and having worked on various Leak Amps I expect they sound similar and just as good!
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Old 20th June 2012, 03:39 PM   #82
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Hi Guys!
First time post, not an expert but know a little bit about this amp.
I had a pair and wish I had kept them - they were superb. I replaced all the caps with new (an easy job - it's all hard wired) and the resistors with equivalent 2W types to keep thermal noise down. I found a great improvement in the sound quality by removing the feedback resistor bypass capacitor - these things really sang! I didn't experience and problems with oscillation as a result but that was just my experience and I am no expert. I sold them to a friend to bring him into the valve community and he has enjoyed them ever since!
Very Best to All,
Graham (aka That Radio Thing)
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Old 20th October 2012, 07:46 PM   #83
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Hi Graham

Nice tip on removing the feedback cap, thanks.
Is it the MA-12's you had ?

I just caught up on the thread, having started to look at mine again.
Issues with the chassis' resolved...
...simply need a bigger chassis / s.

Has anyone tried dropping in a few motor-run caps, here & there ?

Any good tips from peoples, on any aspect of refurbing MA-12's / Mullards, most welcome...
...the refurb. cometh !!!

Cheers.

Si.

Nice builds Wide Range Sound...
...coooool !

Leaks are great Kevin...
...especialy with gravy !

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Old 20th October 2012, 09:07 PM   #84
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Talking MA-12 Schematic...again...+ PICS !!!!

Hi Vacuum heads !

( there's no air, in there ! )

Just thought I'd bung the schematic up again, as it was a few pages back.

4mm test-points near the valves...?

Mmmm...?


Si.

Slightly concerned that if I add regulated heater supplies, the transformer might be a bit pushed.
When they were last 'fired-up' it did get rather warm.
Maybe a small extra transformer for the 'teeny-toob' driver heaters could be good ?

Mmmmmmmm..............?

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Old 8th October 2014, 01:56 PM   #85
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*ahem* Noob here!

I have a full MA12 instruction manual (including a full sheet schematic I think)

I'll need to scan it - only if there is enough interest!

However, I'm looking for a replacement output transformers for my MA12 pair (and TBH the mains tx too) Any ideas if there is an "off the shelf" - the OP tx is marked as as a RADFORD and not a mullard.

Now, back to reading...

CR
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