Firebottle OTL valve amp - pics

[Firebottle]

I know you all love pictures of kit, so I've taken some of my amp.

I built it from scratch (not a kit) in 2000, probably about 30 years since building previous amplifiers with valves, ECL86s if I recall.
It is a Bruce Rozenblit circuit from his first book 'Audio reality'. I have made a couple of minor mods to his circuitry to reduce supply rail hum and incorporate a pre-amp stage.

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle/P1020878.jpg

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle/P1020879.jpg

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle/P1020880.jpg

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle/P1020881.jpg

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle/P1020882.jpg

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle/P1020883.jpg

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle/P1020884.jpg

:cool: Alan

[loo]

Hi Alan, you have some skill there . Is that the worlds smallest valve OTL?
Do you do commission work?
If your looking for a new project I urge you to hunt down the circuit for the Graaf GM20 OTL
I am sure it will interest you,
Merry Christmas regards loo
Ps love the amp name reminds me of my Jerry Anderson faves

[Firebottle]

Hi Paul,
Thanks for the kind comments. Don't know about the smallest OTL, it was a suitable case that housed some sort of test gear, I forget what.

I don't do commission work unfortunately but may re-think after I have completed my latest OTL, when I have found out if it is as good as I'm hoping.

I have built an OTL with a multi output mains transformer and experimented with a balanced configuration along the lines of the GM20. Interesting circuit but very little is new in valve technology :scratch:. I completed it as push-pull in the end and sold it in 2001.

Happy new year to you and everyone on here,
Cheers, Alan

[HighFidelityGuy]

Nice one Alan, that looks superb! I bet it took a long time to work out the component layout in that case. There's not much spare room. :D

I got Bruce's latest book for Christmas as I fancy building an OTL at some point. He has some interesting designs.

What amp are you building next?

[Wakefield Turntables]

:stalks: that is a PROPER amp! It looks so "designed" for the job its untrue. You sure dont have much space under the hood, I'd love to have a listen to it.

[Firebottle]

Thanks Dave & Andrew.

The component layout sort of fell into place, successfully fortunately. The toroidal choke that is bolted onto the back panel is a later modification that removes the hum that was present from the negative output rail.

Bruce's designs are good, this amp is his original 25W design. If you want to build an OTL try Bruce's 'Son of Beast' 15W jobby. It's reasonably simple and has had a very good report on this forum. There are a couple of improvements that can be made to it in my opinion, I'll go into detail if you wish.

The amp I'm building now is on this thread, to my own circuit design:
http://theartofsound.net/forum/showthread.php?t=20955

It is even simpler than the 'Son of Beast' and has no overall feedback, I know that some tube aficionados are keen on no feedback and I'm hoping that it will have an even more 'open' sound; watch the thread above and I will confirm (or not:scratch:).

If anyone is in the vicinity you are all most welcome to call in and listen.
I'll even break out the beer:cool:

Cheers, Alan

[walpurgis]

I like that, clever job!