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Firebottle
29-01-2014, 15:18
This is the starting point of a special project:

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Valve%20amp/P1030725.jpg

:cool: Alan
Gordon Steadman
29-01-2014, 16:36
It looks pretty well er...balanced... on that glass:eyebrows:
Firebottle
09-03-2014, 08:23
The project is now finished and for all you lucky chaps here are some more photos :)

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle%20phono/Sideview.jpg

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle%20phono/Topview.jpg

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle%20phono/Rearview.jpg

It is a fully balanced MC/MM phono preamp, with extra RCA sockets for single ended use.
The power supply is in a separate enclosure with an umbilical connecting cord.

:cool: Alan
Ali Tait
09-03-2014, 09:16
Very nice indeed Alan, can't wait to plug my 401 in!

How's it sounding now with a few hours on it?
Ali Tait
09-03-2014, 09:22
BTW, can you post or email me the final valve line-up?

I'd like to buy some spares in.
Firebottle
09-03-2014, 09:39
It's sounding better than anything else I've built.
I think it has improved with a few hours on but I'm not really trying to follow the improvement in sound.

As far as spares go the valve heaters are current controlled, a design point to prevent surge currents on switch on. The valves should last many thousands of hours as they are operating well within their maximum ratings.

Cheers, alan
Ali Tait
09-03-2014, 10:32
Good to know. Might try some different makes to see how the sound changes. How long did you make the umbilical?
Reffc
09-03-2014, 10:53
Really nice job Alan. How much gain have you used for the MC section?
StuN
09-03-2014, 12:49
Looks great Alan. Do we get to see a picture of the front panel?
Firebottle
09-03-2014, 12:49
The umbilical is nearly 1.2m long.

The measured gain for MM is 37dB and for MC is 62dB at 1Khz.
Firebottle
09-03-2014, 12:51
Stuart, it's nothing much to see, the same as previous builds.
I haven't taken a photo yet as I'm waiting for some labels.
Ali Tait
09-03-2014, 12:58
The umbilical is nearly 1.2m long.

The measured gain for MM is 37dB and for MC is 62dB at 1Khz.

Thanks Alan, plenty long enough.
Barry
09-03-2014, 16:05
Are you able to change the cartridge loading (for both MM and MC) externally, i.e. is it switchable?

If I were to commission you to make one for me, how much would it cost?
Firebottle
09-03-2014, 19:48
PM sent Barry.
£900 with Takman resistors and Mundorf capacitors, £650 with standard components.

Cheers, Alan