Croft Iosis Power Amp

[terrybites]

Hi all,

I bought a Croft power amp from Noel Cloney back late last century. It was a demo model and was supplied without original packaging or manual. I bought it for it's sweet sound and am still delighted with it today. I'd like to know more about the amp and got in touch with Glenn Croft directly. He said it was built in tiny quantities and that no documentation remained. It has 'Iosis' inscribed on a plate on the back and a chrome front plate. The valves are set horizontally - twelve small valves set in three rows of four (stacked) and one additional similar sized valve positioned below a much larger valve. You will gather that I am no expert!

I'd love to know more about it - spec, reviews etc. Maybe one of the members has one or knows about it.

With best regards,

Terry

Sent from my iDad

[Diapason]

That sounds pretty interesting. I don't know anything about it myself, but Cybot knows a thing or two about Croft, so he may be able to help?

PS I love this:

Sent from my iDad

[Ciaran]

PS I love this:

Sent from my iDad

Wow! I didn't realise we had cyborg members already!

[cybot]

Hi all,

I bought a Croft power amp from Noel Cloney back late last century. It was a demo model and was supplied without original packaging or manual. I bought it for it's sweet sound and am still delighted with it today. I'd like to know more about the amp and got in touch with Glenn Croft directly. He said it was built in tiny quantities and that no documentation remained. It has 'Iosis' inscribed on a plate on the back and a chrome front plate. The valves are set horizontally - twelve small valves set in three rows of four (stacked) and one additional similar sized valve positioned below a much larger valve. You will gather that I am no expert!

I'd love to know more about it - spec, reviews etc. Maybe one of the members has one or knows about it.

With best regards,

Terry

Sent from my iDad

Lovely to come across another Croft owner/devotee! It's a beautiful looking amp and must have been made around the time of the Epoch/Series 5 amps which I used to own as they had a similar 'look' to yours. All I can add is, if Glenn himself can't give much in the way of the info you're looking for, then I have no chance lol! For what it's worth I've never heard of it. What type of valves are used? Do you have to set the bias manually? Somehow I doubt it with all those valves :) However if I do find something you'll be the first to know.....

Edit: I went through my Croft folder - yes, I'm one if those sad people who collected anything Croft! - and didn't find a mention of the Iosis amp! But it was great to catch up with all the mail, brochures, reviews etc etc. Even a Christmas card from Glenn himself! I was also shocked to discover the price of some of the items! The most expensive item listed was the Mesmeris which had a listed price of £8500.00!!!!!! But then again it was a monobloc pure class A Triode set up. I'm sure they had even more expensive gear but I'm afraid to look! Anyway consider yourself the lucky owner of a one-off :)

[Fran]

Like cybot, I can't tell you anything.

At least you can always send it back to Glenn if you need anything done with it......



Fran

[cybot]

Like cybot, I can't tell you anything.

At least you can always send it back to Glenn if you need anything done with it......



Fran

Exactly :) One of the most honest and dependable people I know....

[terrybites]

Hi fellas and thanks for your interest and info. I just heard back from Glenn as follows...

Hi Terry,
it looks like an upmarket version of the Series 5 with a valve regulated ht supply and C-core output transformers.
The valves will have what they are written on them - the output valves are EL84 and the power supply valves will be 6AS7G [large one] ECC83 and 85A2 - the others I don't know.
The output power will be 25 - 30W/channel.
All the best,
Glenn.

I'm running it through a pair of Sonus Faber Auditor M's and it all sounds mighty fine!

Back in touch soon.

Terry

[cybot]

Hi fellas and thanks for your interest and info. I just heard back from Glenn as follows...

Hi Terry,
it looks like an upmarket version of the Series 5 with a valve regulated ht supply and C-core output transformers.
The valves will have what they are written on them - the output valves are EL84 and the power supply valves will be 6AS7G [large one] ECC83 and 85A2 - the others I don't know.
The output power will be 25 - 30W/channel.
All the best,
Glenn.

I'm running it through a pair of Sonus Faber Auditor M's and it all sounds mighty fine!

Back in touch soon.

Terry

Great stuff! I wasn't too far off :)

[Diapason]

Sounds pretty tasty, and I've always been a fan of those speakers.

[tony]

For croft that is a really very nice looking amp.I am using a borrowed maybe it will remain here series 5 amp. It must be a mkii or mki as it looks completely different to your unit Terry. It is a standard config with all the valves sitting onto. It currently has the cage on it but I always have a laugh when I peer through the cage as it looks like there is about 28 valves in there. Ok that is an overstatement but there is 8 EL84's the big valve and a variety of signal valves. For the size of the chasis it is an incredible number of valves for such a small footprint. It His later designs seemed to go completely away from that type of arrangement as the later ones only have a few signal valves (ECC83 or 82 I think) and are hybrid design.
Sound wise i really like it and I have read conflicting stories on the web about its power output. I believe it is 25w's but some reviews put it at 40w which I doubt. It still has plenty of oomph to drive spendor a6's.