Audiolab 8000a Speaker Protection

[alfajerry]

Does anyone know if a total electronics novice could adjust/disable the 8000a's speaker protection system?
Years ago Audiolab told me it could be adjusted at the factory so it is possible.
Thanks for any help.

 

[pinkmouse]

What are you trying to achieve?

 

[richie00boy]

The VI limiting circuit is disable-able, but I have to ask why you want to do it. If you feel it's encroaching on your listening it's probably time to buy a more powerful amp. The protection is there for a reason.

 

[sreten]

Hi,

Yes a relative novice can adjust the trip limits in an Audiolab 8000A.

The procedure is outlined in the service manual but it is fiddly, I can't
remember the exact details, I think a set of resistor values is needed.

The trip limits should only be adjusted because the load is low impedance.

/sreten.

 

[mikeks]

Hi,

Yes a relative novice can adjust the trip limits in an Audiolab 8000A.

The procedure is outlined in the service manual but it is fiddly, I can't
remember the exact details, I think a set of resistor values is needed.

The trip limits should only be adjusted because the load is low impedance.

/sreten.

Hi Sreten...you wouldn't happen to have a copy of that service manual, would you?

 

[sreten]

Hi,

I do, somewhere at home, I'll have a look for it tonight.

/sreten.

 

[anatech]

Hi Sreten,

you wouldn't happen to have a copy of that service manual, would you?

I'd be interested also if it's not too much trouble. I've repaired a few with a schematic only.

I'm still uneasy about messing with the protection circuit. You never want to disable it completely. That is asking for trouble.

-Chris

 

[alfajerry]

I't s because it doesn't go as loud as it should before it cuts the power.
When I spoke to Audiolab several years ago and described the other equipment and the listening environment, they said straight away that it must be set too low, but I couldn't afford to have them change it.
If anyone has a guide to doing this I'd appreciate a copy.
Thanks.

 

[sreten]

Hi,

please tell me the serial number of the 8000A.
For the correct models the procedure is straightforward,
I was confusing it with resetting the bias.

The procedure prevents the mute relay operating on
high level bass transients into low impedance loads.

/sreten.

 

[alfajerry]

Thanks for your interest 'Sreten'

S/N: 207B76250

Jerry

 

[sreten]

Hi,

I have schematics for serial numbers 87........ and 89.............

/sreten.

 

[sreten]

the mods only work for 87...... , 89........ already has the diodes fitted.

The resistors are towards the back of the power amp board.

/sreten.

 

[mikeks]

hi sreten...

Would appreciate a .pdf copy of that manual..

cheers!

 

[sreten]

hi sreten...

Would appreciate a .pdf copy of that manual..

cheers!

Hi,

I have a photocopied paper version,
quality of some of the A3 diagrams is poor.

At work we are considering implementing our own PBX, one of its
facilities eventually will be FAX to PDF conversion, so we will at some
point in the future we will be able to use a scanner to generate PDF.

Which is fine for the A4 pages, still stuck with the poor quality A3s.

/sreten.

 

[mikeks]

Hi,

I have a photocopied paper version,
quality of some of the A3 diagrams is poor.

At work we are considering implementing our own PBX, one of its
facilities eventually will be FAX to PDF conversion, so we will at some
point in the future we will be able to use a scanner to generate PDF.

Which is fine for the A4 pages, still stuck with the poor quality A3s.

/sreten.

all you need is pdf995, freely available here:

www.pdf995.com

 

[richie00boy]

Or even just scan the pages in as PNG files (which are generally smaller and better quality than PDF anyway).

But I suspect sreten's problem is that he doesn't even have a scanner.

 

[mikeks]

or...scan to .png, and then 'print' to pdf995..

 

[richie00boy]

LOL why can't you convert to PDF if you want? PNG is smaller to email

 

[mikeks]

Hi,

I have a photocopied paper version,
quality of some of the A3 diagrams is poor.

At work we are considering implementing our own PBX, one of its
facilities eventually will be FAX to PDF conversion, so we will at some
point in the future we will be able to use a scanner to generate PDF.

Which is fine for the A4 pages, still stuck with the poor quality A3s.

/sreten.

sreten, can you post a complete schematic of Audiolab's SOA protection circuit?

 

[sreten]

sreten, can you post a complete schematic of Audiolab's SOA protection circuit?

Hi,

You pretty much have all the info.
(Unless there is some temperature sensing I've missed)

There is no SOA apart from the output current tripping the relay.
(As far as I can tell)

R501/2 and R503/4 are connected to the output pair current
sensing resistors R493/4 2.2R double resistor packages.

/sreten.