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Amp Internals 2

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djeddie View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote djeddie Quote  Post ReplyReply Direct Link To This Post Posted: 01 August 2020 at 8:55am
Originally posted by jbl_man jbl_man wrote:

What's the line of splodge running down the centre of the heatsink?


I'm glad that was answered sensibly and someone with, let's say, a childish sense of humour didn't suggest Kevin got exited over McGregor internals.

I'll get my coat.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 01 August 2020 at 11:46am
Quote do their amplifiers have a bunch of those silly ZTX transistors


I dont this this one does, that would be the original melksham citronics, ie the original company. This amp is really a McGregor, I think probably made after Skytronic bought the name.
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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 11:02am
Citronic PSX4. I was quite expecting a Skytronic innards and got ready to grimace, but was pleasantly surprised by a real Citronic.






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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 11 August 2020 at 12:24pm
I take your word for it that there is one in there somewhere under that grime! That has seen some service. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote csg Quote  Post ReplyReply Direct Link To This Post Posted: 11 August 2020 at 12:59pm
Those old PSX4’s are almost bombproof. A friend of mine had 4 of those in his hire stock from the mid 90’s until around 2010. I once worked out each had earned over £20K in rental fees!
“The fact is this is about identifying what we do best and finding more ways of doing less of it better”
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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
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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
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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
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