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Earplug View Drop Down
Old Croc
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Joined: 03 January 2012
Location: Europe
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Points: 7005 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 15 March 2023 at 11:35am
Those old Peaveys are bloody tanks!   LOL

Well worth fixing.   Smile
Earplugs Are For Wimps!
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EmPro View Drop Down
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Joined: 26 June 2020
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Points: 356 		Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 15 March 2023 at 11:37am
I like the're so easy to fix,if you have the parts you need is a 30min job Big smile
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Joined: 26 June 2020
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Points: 356 		Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 15 March 2023 at 10:51pm
How my CS1000X looks like,i love this amplifier Big smile


Edited by EmPro - 15 March 2023 at 10:52pm
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Joined: 06 September 2013
Location: Surrey
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Points: 242 		Post Options Post Options   Thanks (0) Thanks(0)   Quote shaun1264 Quote  Post ReplyReply Direct Link To This Post Posted: 25 March 2023 at 7:36pm
Chance buy on a Crown D75... Pleasant surprise someone changed the mechanical buzzing transformer to  a torriod. Typical cooking PCB from the 320ohm resistor complete with vaporised tracks.  Upgraded R1 910 resistor to a 5watt and relocated to the side of the PCB board.  (sorry no pic), changed the 10v zener diodes for the opamps supply, new caps, put back together, power up, several hundred mV DC offset on both channels!!.  re-examine board and find two more broken tracks.  ... fixed them and power up and now perfect.  Adjusted bias as manual states.  Very low THD. 




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luton_soundman View Drop Down
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Joined: 03 August 2010
Location: Bedfordshire
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Points: 4472 		Post Options Post Options   Thanks (0) Thanks(0)   Quote luton_soundman Quote  Post ReplyReply Direct Link To This Post Posted: 25 March 2023 at 8:24pm
Very nice
Sound Hire/Sales new/used equipment.
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Points: 356 		Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 25 March 2023 at 8:58pm
Hmmm..indeed looks awesome with that torroidal in it,hmmm i think i should do the ,,upgrade" to my D75 as soon as possibile.. didn't explode...yet LOL but i can see hi temp marks on the pcb Confused


Edited by EmPro - 25 March 2023 at 9:01pm
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Points: 356 		Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 25 March 2023 at 9:04pm
However i bought mine without ear racks..and never found ones to buy for it....Confused it looks pretty ugly without them Confused

Edited by EmPro - 25 March 2023 at 9:05pm
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shaun1264 View Drop Down
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Points: 242 		Post Options Post Options   Thanks (0) Thanks(0)   Quote shaun1264 Quote  Post ReplyReply Direct Link To This Post Posted: 25 March 2023 at 10:36pm
Another one of Gerald Stanley's patent topology designs.  Class AB+B.   Very large amounts of negative feedback to get THD down very low.  

A little bit of info here for the technical minded...  When TIM distortion was discovered by Matti Otala back in the 70s he incorrectly blamed too much negative feedback as the cause..   infact, it's actually caused by not enough feedback and slow semiconductors back then. ...slew induced distortion.  This gave Crown a bit of bad rap way back then as people knew Crown used large amounts of negative feedback...  Audiophiles still believe in this myth! Infact Crown amps never had any TIM distortion.  They all measured well.   
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EmPro View Drop Down
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Joined: 26 June 2020
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Points: 356 		Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 25 March 2023 at 10:43pm
Clever design,basicaly on low power the output transistors are off...is working on the drivers,no bias thru outputs...as you rise the volume the power outputs will kick in and take the heavy load further...nice one..and helps a lot with thermal stability.
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shaun1264 View Drop Down
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Points: 242 		Post Options Post Options   Thanks (0) Thanks(0)   Quote shaun1264 Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2023 at 11:43am
Absolutely correct.  pre drivers act as class A, drivers act as class AB and output act as class B.  Driver and pre drivers have good fast speed and outputs lower speed (much more stable and durable) outputs act as boosters.  Crossover notch is literally non existent.  

Idle power much lower too!  
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EmPro View Drop Down
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Points: 356 		Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2023 at 12:00pm
Indeed,my one was faulty,one output transistor shorted and the ch was off,no other faults apart from that,i replaced all 4 outputs just in case with MJ15024....and rock and roll since Big smile,amazing good schematic with proper protection,not even a resistor blown...just one transistor and done...no other faulty parts,impressive,that remainds me of a Crown PowerTech 3....big,strong and heavy brute of an amplifier...right ch was off...left ch working as it should...the first transistor i checked was shorted..pulled off..no more short...i tested the amp both ch working now....i was amazed...however i replaced all 16 outputs with new MJ21194/MJ21195 from OnSemi..just to be extra sure that amplifier will perform flawless,the driver transistors we're strong and matched so no damage taken,the amplifier is runnig strong since repair has been done,i love these designs...

Edited by EmPro - 26 March 2023 at 12:04pm
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Points: 356 		Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2023 at 2:46pm
ASHLY FET-1500M 1988,not sure if the outputs are genuine for this device as i think this model comed with Hitachi's K135 and J50,even the pcb indicates J and K...but however,is working flawless and not really taken care of it....


Edited by EmPro - 05 April 2023 at 2:49pm
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