Hi RM, may be possible to have the schematic of cairn 4808 ? My version has only one large toroidal transformer
Thanks. Best regards
ernesto.paris@aol.com
Hi there,
it's my first post here on diyaudio forum, so hello for everyone!
@RM could You please send service manual for Cairn Mea (North Face version on my e-mail address charles.enak@gmail.com?
Mea utilizes same fets as 4808A. Unfortunately i had to replace them with new version IRFP150/9140N (burned out), because IRFP150/9140 are no longer available. It,s working, but now I'm not sure about quiescent current.
Thanks in advance!
CE
I don’t have service manuals. They never made any. I have only schematics. But no NF. I do however have original fets. Used ones. The idle current was always very low because they originally didn’t have Vbe transistors so most of them suffered thermal runaway if played a bit loud. In the second and third year they introduced these.
I still have empty cabinets of the Classe A and the accompanying preamp. Gorgeous cabinets, rotten innards. The preamp as delivered new to us had over 30 wires on the bottom layer. The power amp could go from 30 to 90 degrees heat sink temp in the matter of hours depending on level. Also because no Vbe to sense the temp.
R
I still have empty cabinets of the Classe A and the accompanying preamp. Gorgeous cabinets, rotten innards. The preamp as delivered new to us had over 30 wires on the bottom layer. The power amp could go from 30 to 90 degrees heat sink temp in the matter of hours depending on level. Also because no Vbe to sense the temp.
R
I see... Thats pity.
Maybe You want to sell those original fets You mentioned?
If they are matched, then I may be interested 🙂
I matched my IRFP150/9140N(PbF) fets using Mr. Pass method described in this article: https://www.firstwatt.com/pdf/art_matching.pdf
Everything is working pretty good with quiescent current adjusted to ~150mA (~71mV around emitter 0R47 resistors), but I'm not sure if that was exactly factory setting of bias.
Heatsink runs about 56 Celsius degrees, fets runs about 61 Celsius degrees, and 150mA is pretty stable for normal and louder listening.
Mea utilizes two pairs of IRFP150/9140 - maybe there were similar builts, integrated amps maybe, and maybe quiescent current be the same for those amps?
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The only way to get a good reliability is a complete re-design of the present circuit - the retention of the original condition does not lead to a permanent operation in the right manner.
With the existing heatsink size, it is not possible to operate with the intended supply-voltage.
This means, a new transformer with at most half the value of voltage is necessary in any case.
check out this URL:
https://www.abeltronics.co.uk/repair.php?ID=cairn
Which developer was working here at those days ?
And what happens in this company in the meantime ?
This are the owner's at those days:
Gilles Bélot/Benoît Rabozzi
http://web.archive.org/web/20040205021215/http://www.cairn-ezo.com/index_va.html
https://vn.linkedin.com/in/benoit-rabozzi-9173212
https://www.techradar.com/reviews/audio-visual/hi-fi-and-audio/amplifiers/cairn-fog-3-212719/review
https://hifi.nl/recensie/1547/Cairn-Aria.html
maybe on this closed french forum are additional information
https://web.archive.org/web/2015071...4810-gain-47-compte-rendu-d-ecoute-t8606.html
https://web.archive.org/web/20080310190522/http://forum.icairn.fr/
email-address: icairn@icairn.com
With the existing heatsink size, it is not possible to operate with the intended supply-voltage.
This means, a new transformer with at most half the value of voltage is necessary in any case.
check out this URL:
https://www.abeltronics.co.uk/repair.php?ID=cairn
Which developer was working here at those days ?
And what happens in this company in the meantime ?
This are the owner's at those days:
Gilles Bélot/Benoît Rabozzi
http://web.archive.org/web/20040205021215/http://www.cairn-ezo.com/index_va.html
https://vn.linkedin.com/in/benoit-rabozzi-9173212
https://www.techradar.com/reviews/audio-visual/hi-fi-and-audio/amplifiers/cairn-fog-3-212719/review
https://hifi.nl/recensie/1547/Cairn-Aria.html
maybe on this closed french forum are additional information
https://web.archive.org/web/2015071...4810-gain-47-compte-rendu-d-ecoute-t8606.html
https://web.archive.org/web/20080310190522/http://forum.icairn.fr/
email-address: icairn@icairn.com
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What do you mean by re-design the present circuit? I was talking about Mea Monoblocks, not K5 amp, and not Classe A construction but the NF ones, and IMO they are a very good construction:
As i said above - 56C on heatsink with 150mA quiescent current. IRFP150/9140N (5-th generation) got a little bit different specs as IRFP150/9140 (3-th generation). Probably 3-th are better for audio use (lower RDSon), but they are no longer available on stock (mouser , digikey etc.), so i used the N version, and with success I think. But still I'm not sure that 150mA.
@RM maybe You have schematic for 4810 dual mono? That construction looks be pretty similar to Mea Monoblocks.
Sorry for my poor english, I'm trying not to use google translator 🙂
CE
I met Gilles on two separate occasions. A very gentle and polite man. Was he the designer? I couldn’t say.
I don’t have 4810 data. Must have come after our involvement. We had a total of 19 different products, all defective. That were left sitting in a local warehouse for six months without any action from Cairn. They couldn’t afford to pay the VAT to take them back for repair.
We took the pallets back, I modified and repaired the amps, the rest went to the scrap yard.
I have maybe 20-30 output devices. I need to retain a few, but will PM you with a offer when I’m home again.
The amp you posted picture of I have never seen before. At one time we also had YBA, the experience almost mimicked Cairn. Kora and Artec the same. You can safely assume I’m a bit weary of French electronics, Dassault Mirage notwithstanding.
R
I don’t have 4810 data. Must have come after our involvement. We had a total of 19 different products, all defective. That were left sitting in a local warehouse for six months without any action from Cairn. They couldn’t afford to pay the VAT to take them back for repair.
We took the pallets back, I modified and repaired the amps, the rest went to the scrap yard.
I have maybe 20-30 output devices. I need to retain a few, but will PM you with a offer when I’m home again.
The amp you posted picture of I have never seen before. At one time we also had YBA, the experience almost mimicked Cairn. Kora and Artec the same. You can safely assume I’m a bit weary of French electronics, Dassault Mirage notwithstanding.
R
I don't know what happened at the time but some amps from the Triangle brand (Nemo previously) clearly had the same schematics as the Atoll amps.
Cairn disappeared without a trace and Gilles Bélot returned to his job as a teacher.
I don't know anything more except that many people have found themselves with broken devices and without a solution because they "gone to the grave" without leaving any technical documents.
Indeed, they had made strange technical choices, even "beginner" choices, a bit like in the first Atoll.
I have a Rotel RTC-970 and I lost it's remote(Model RR 970). The unit now is stuck in Pro-Logic mode, and the only mode selection is only possible on the RR 970 Remote controller.
I really like this unit, but being able to switch to stereo mode is important for me as I can't use it as a stereo pre-Amplifier without it.
So is there any way around this problem? At least converting it somehow to stereo mode. Replacement remotes .i could not afford remort price shipment to pakistan
I really like this unit, but being able to switch to stereo mode is important for me as I can't use it as a stereo pre-Amplifier without it.
So is there any way around this problem? At least converting it somehow to stereo mode. Replacement remotes .i could not afford remort price shipment to pakistan
😉 Ha ha once bitten twice shy. However excellent French made electronic parts exist. The French audio electronics are best avoided (in general) but I am glad Le Maison de l'Audiophile existed. Hiraga-san....
Psst! Micromega....
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Hello.
Please send me the circuit diagram of the Cairn 4808 amplifier.
Version with one transformer 330VA-sec.2x30V 5.5A.
I'm having some problems with the repair, unfortunately I can't find a schematic anywhere.
My address:
andrzej5430@gmail.com
Sorry for my English, I'm using a translator.
Regards
Andrew