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Amp Internals 2

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M4trix View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote M4trix Quote  Post ReplyReply Direct Link To This Post Posted: 11 August 2020 at 7:28pm
@Kevin,

do you first inspect the amplifiers for spiders, scorpions before you put your hands in it ? It looks like a
terrarium for such nasty bugs. Ouch Wink
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Post Options Post Options   Thanks (0) Thanks(0)   Quote simonp1100 Quote  Post ReplyReply Direct Link To This Post Posted: 11 August 2020 at 8:11pm
The only irritating bit of these are the hybrid driver circuit, when they go wrong just bin the amplifier. Confused

There was a long time ago an engineer who copied the Citronic hybrid circuit and designed a PCB which was a copy of the original but using surface mount components, don't know if they are still available.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 11 August 2020 at 10:18pm
Quote do you first inspect the amplifiers for spiders, scorpions before you put your hands in it


No poisonous animals of any kind in the UK! Snide political comments aside....

Quote an engineer who copied the Citronic hybrid circuit


A&J Audio

Edited by kedwardsleisure - 11 August 2020 at 10:24pm
Kevin

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbl_man Quote  Post ReplyReply Direct Link To This Post Posted: 12 August 2020 at 9:30am
Is this a Buz mosfet thing? Must have been one of the very last of the UK amps?
Be seeing you.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 12 August 2020 at 2:34pm
no it's bipolar, MJ15003/MJ15004. All working now, though nothing to brag about!

The thick film hybrids were a bit of a fad across the industry a few years ago, I remember the early QSC step drivers and housekeeping modules were like that before they reverted to conventional construction, I've also seen them in AKG radio mics where if you drop the mic, the ceramic tile shatters. Sprint speed controllers had them but they reverted to a standard pcb. Siemens used them in industrial robot controllers. AVO used them in their late-model AVO-8 where they could be calibrated by etching the carbon film resistors 'live' (I think precision SMT resistors are made ina similar way, if you look under a glass you can often see a little slot burned part-way through). I've only seen the Citronic ones in the last generation of uk amps, the PPX Conquest had them and I've had them fail after a blow-up, though you can often repair them.

Edited by kedwardsleisure - 12 August 2020 at 2:34pm
Kevin

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Post Options Post Options   Thanks (0) Thanks(0)   Quote kipman725 Quote  Post ReplyReply Direct Link To This Post Posted: 02 September 2020 at 10:39am
Crown Macrotech MA5002VZ.  Came to me in a bit of a mess so far I have got one channel working (final image).  No idea how the internal cable routing is meant to work to avoid them contacting the fan blades as it had already been messed with when it got to me.  Signal lights are weird in that if there is a high level of distortion (such as broken output) they will light up fully with no signal.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 03 September 2020 at 9:19pm
a mate of mine has cushion covers that match your curtains
Kevin

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rareun Quote  Post ReplyReply Direct Link To This Post Posted: 12 November 2020 at 10:12pm
Sorry, new to this and I think I may have posted this same question 3 times now but is it true that there's only 20 of these? I have 2 of them
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Post Options Post Options   Thanks (0) Thanks(0)   Quote knet94 Quote  Post ReplyReply Direct Link To This Post Posted: 12 November 2020 at 11:51pm
Can't work out what you're referring to.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cravings Quote  Post ReplyReply Direct Link To This Post Posted: 13 November 2020 at 12:01am
yeah.. there's over 200 pages of stuff here.. hit quote rather than reply maybe
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rareun Quote  Post ReplyReply Direct Link To This Post Posted: 13 November 2020 at 2:07am
Originally posted by scott101 scott101 wrote:

OHM's best kept secret, an FL1200 MK2 amplifier. Only 20 were made and out of that, only 12 got out into the wild.


 

















Hi this was the quote I was referring to. Are they really this rare? I have 2 of them
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rareun Quote  Post ReplyReply Direct Link To This Post Posted: 13 November 2020 at 2:08am
MkII that is
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