C-Audio Pulse Projects

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   Just wondering if anyone might be interested in some partially or non-working C-Audio Pulses as spares or repair projects?
I have been running Pulse 2x1100's on my own system for years and sound-wise I really like them.  However I am starting to move over to slightly more modern designs for various reasons.  That means it's probably unlikely I will ever get round to finish looking at the ones which are long term residents in my workshop.

I have one 2x1100 very much in bits which needs a complete output stage rebuilt and realistically may be no longer worth the effort and a 2x650 which is essentially working but suffers from a switch on/off thump on the output which I have never managed to track down the cause of.  There is also another 2x1100 on the shelf which I've spotted an issue with the rail commutation where there is a brief oscillation but I can't decide if it's actually a fault with or it's just a design feature I've never paid attention to before!

In addition, I also have a number of fully working 2x1100's which I should consider selling if anyone fancies a couple.

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ceharden Members Profile Send Private Message Find Members Posts Add to Buddy List The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776	Post Options Post Reply Quote ceharden Report Post Thanks(0) Quote Reply Topic: C-Audio Pulse Projects Posted: 30 July 2021 at 12:16am
	Just wondering if anyone might be interested in some partially or non-working C-Audio Pulses as spares or repair projects? I have been running Pulse 2x1100's on my own system for years and sound-wise I really like them. However I am starting to move over to slightly more modern designs for various reasons. That means it's probably unlikely I will ever get round to finish looking at the ones which are long term residents in my workshop. I have one 2x1100 very much in bits which needs a complete output stage rebuilt and realistically may be no longer worth the effort and a 2x650 which is essentially working but suffers from a switch on/off thump on the output which I have never managed to track down the cause of. There is also another 2x1100 on the shelf which I've spotted an issue with the rail commutation where there is a brief oscillation but I can't decide if it's actually a fault with or it's just a design feature I've never paid attention to before! In addition, I also have a number of fully working 2x1100's which I should consider selling if anyone fancies a couple.

Phil B Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 21 November 2004 Location: Melbourne Status: Offline Points: 2328	Post Options Post Reply Quote Phil B Report Post Thanks(0) Quote Reply Posted: 30 July 2021 at 12:30am
	I would love the 2 x 650 for spares but I think the air freight will be more than it's worth !! .p.
	Mostly harmless.... except if catering is shut. Solar Sound System Shennanigans..http://diyhifi.biz/

ceharden Members Profile Send Private Message Find Members Posts Add to Buddy List The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776	Post Options Post Reply Quote ceharden Report Post Thanks(0) Quote Reply Posted: 30 July 2021 at 12:33am
	Shame, even container shipment is expensive at the moment.

M4trix Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 23 June 2009 Location: Croatia Status: Offline Points: 445	Post Options Post Reply Quote M4trix Report Post Thanks(0) Quote Reply Posted: 30 July 2021 at 9:46pm
	Interesting. So far I've only seen Yorkville using TO-3 ( MJ ) devices in their class-H amplifiers. @Ceharden, would you be so kind and tell me the power supply voltages HT/MT ? Cheers. Edit: for the 1100 model please. Edited by M4trix - 30 July 2021 at 10:07pm

ceharden Members Profile Send Private Message Find Members Posts Add to Buddy List The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776	Post Options Post Reply Quote ceharden Report Post Thanks(1) Quote Reply Posted: 30 July 2021 at 11:55pm
	They're approximately 70 and 140V from memory, been a while since I've measured them.

M4trix Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 23 June 2009 Location: Croatia Status: Offline Points: 445	Post Options Post Reply Quote M4trix Report Post Thanks(0) Quote Reply Posted: 31 July 2021 at 12:35am
	Thanks mate. Edited by M4trix - 31 July 2021 at 9:35pm

M4trix Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 23 June 2009 Location: Croatia Status: Offline Points: 445	Post Options Post Reply Quote M4trix Report Post Thanks(0) Quote Reply Posted: 31 July 2021 at 9:31pm
	*bumpinator Edit: Since I have a bunch of NOS MJ15022/23, I was thinking to clone this amplifier for fun. I don't want to waste all these transistors for nothing especially I don't want them discarded. Over 100 matched devices. Those voltages are too high for them so I have to adapt the whole project. Full SMD conversion except power resistors etc. And those silly ZTX transistors... get out of my sight ! Edited by M4trix - 31 July 2021 at 9:35pm

ceharden Members Profile Send Private Message Find Members Posts Add to Buddy List The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776	Post Options Post Reply Quote ceharden Report Post Thanks(0) Quote Reply Posted: 31 July 2021 at 9:39pm
	You could do something along the same lines quite easily, just reducing the supply Voltages. I have often considered doing my own version, incorporating all the known issues, especially in the PSU. Never going to have the time though.

M4trix Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 23 June 2009 Location: Croatia Status: Offline Points: 445	Post Options Post Reply Quote M4trix Report Post Thanks(0) Quote Reply Posted: 31 July 2021 at 11:07pm
	Will come out with the schematic. I'm currently having problems with finding proper transistors. BF422/BF423 are way obsolete. Any suggestions ? Edit: MJE5731A/TIP50 are going out as well. MJE15032/MJE15033 will do the business. Edit 2: Vbe multiplier, TTA006B ( 2SA1837 ) Edit 3: these might replace BF422/423 --> BF722/BF723 or BF720/721 Edited by M4trix - 01 August 2021 at 6:05pm