Interest check for valve phono amp for AoS forumites

[Firebottle]

One of the AoS members asked what I would be doing with the phono preamp that is doing the round robin between members. I offered it for trial just so that folks could try a valve pre, but I was asked if I might consider making some for AoS members.

After giving this some thought I need to test the interest on the forum.
It would only be a 'hobbyist' production run, exclusively for AoS.

Here are the findings so far of the performance (already improved upon):
http://theartofsound.net/forum/showthread.php?t=24413
http://theartofsound.net/forum/showthread.php?t=24485


I am thinking along the lines of a low case with the valves in full view on top:

http://thumbs.ebaystatic.com/pict/1210753830964040_1.jpg

Your thoughts chaps?

:cool:Alan

[Firebottle]

I have finalised the design and constructed the first sample of the phono amp.

It has exceeded expectations as on first listen I was blown away by the scale and clarity of the soundstage.

This first example has been sold, I will leave it to the recipient to reveal himself if he so wishes.

As in accordance with usual forum style here are the images for your delectation:

General view
http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle%20phono/P1030047.jpg

Front panel
http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle%20phono/P1030052.jpg

Rear panel
http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle%20phono/P1030049.jpg

The all important valves
http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle%20phono/P1030050.jpg

and last but not least, the internals
http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle%20phono/P1030053.jpg

I and others shall be doing more listening, and I will be doing further testing and will report in due course,

:cool: Alan

[Ali Tait]

Nice Job!

[Mr Kipling]

Can I ask what resistors you use?

Still looking for modest metal film that doesn't sound glazy. Beyschlag seem reasonable and Audionote used to use them. Don't know if they still do.

[Spur07]

looks grand Alan, looking forward to hearing it. :)

[Firebottle]

Can I ask what resistors you use?

Still looking for modest metal film that doesn't sound glazy. Beyschlag seem reasonable and Audionote used to use them. Don't know if they still do.

I'm using mainly Welwyn with a couple of Vishay thrown in for good measure :rolleyes:

:cool:Alan

[Firebottle]

There has been a bit of activity going on in the background so I thought I would post an update.

The first two preamps have been sent out but have encountered a common problem with the power supply.
When Gordon and I had a good listen to the first sample it sounded great.....to us. In reality the power supply was squealing at a high frequency that was not audible to us old f*rts.

The problem was it was very audible to the two recipients so the preamps have had to be re-fettled.
They are now being made with a 12-15 V DC input so that an external power supply of your choice can be used.

The updated preamps will be with their respective recipients very soon, watch this space.

:cool:Alan

[Macca]

How much are you knocking them out for Alan? I may be in the market for a new phono stage.

[Firebottle]

Hi Martin,

I'm asking £230 plus post and packing. P+P is about £25, it was £21 but I'm packing more securely and it's added to the weight.

Cheers,
Alan

[Macca]

Thanks Alan - that's within my price range :)

[Emmings]

Alan

I too am in the market for a new phono stage and this looks very tempting and would be interested in one in the near future.

Awaiting updates with interest:)

Cheers
Dave

[Mike g]

Looks very good. I assume it's still a MM input stage? I've got a low mc cart but would like to try it 😢

[Firebottle]

Yes it's MM input, here is the spec of the amp:

Regulated High Tension supply.
Surge protected dc heaters.
Passive RIAA equalisation.
Frequency response: ------------------------------ wide ---------------------------------
Supply voltage: 12 – 15 volts DC, 1.7A
DC input: 2.5mm DC socket, centre pin positive.
Input impedance: 47 Kohm, 80 pF.
Gain: 44 dB @ 1KHz.
Output impedance: 600 ohms.

:cool:Alan

[Tarzan]

One of the AoS members asked what I would be doing with the phono preamp that is doing the round robin between members. I offered it for trial just so that folks could try a valve pre, but I was asked if I might consider making some for AoS members.

After giving this some thought I need to test the interest on the forum.
It would only be a 'hobbyist' production run, exclusively for AoS.

Here are the findings so far of the performance (already improved upon):
http://theartofsound.net/forum/showthread.php?t=24413
http://theartofsound.net/forum/showthread.php?t=24485


I am thinking along the lines of a low case with the valves in full view on top:

http://thumbs.ebaystatic.com/pict/1210753830964040_1.jpg

Your thoughts chaps?

:cool:Alan


Yes, will a black front plate be available?

[Firebottle]

Andy, I'm afraid not :(

If you are desperate for a black front you could have it sprayed or anodised, but that would be down to you to achieve.

:cool: Alan

[Gazjam]

Alan,
count me in as interested in one.

Looking for a best bang for buck box to get my Gyro talking to the amp.
This is it.

[Soulman]

I'd like to buy one as well if you're still making them, it may be september as I've got a big holiday to pay for but am happy to wait in line from then onwards....