Valve pre-amp.......

[ecca]

Patience Boyng.
Firstly a massive thank you to Piet for enabling all of this.
The first plane that was built wasn't Concorde.....
I have entire faith in this valve unit, today I tried it at the North Notts Club having modified it from the very first trials at the Hankies and although it sounded like a bathroom reverb - I was happy enough.
It has great flexibility and power, the 2 independent valve pre-amps make this so.
The arrangement I now have is one of valve pre-amp - echo unit - post echo valve amp but the unit I've built is capable of changing this arrangement internally, without soldering, to one of valve pre-amp - valve-pre amp 2 - echo unit.
It's also capable of sending the guitar signal straight through, no pre-amp, and 'valving' the signal to and from the echo unit, and much more.
These things I evaluate.
Rest assured that I'm happy with this to the point where I've ordered the master PCBs that I've designed to facilitate the echo daughterboard, to generate the HT and heater voltages, I've also ordered engraved nameplate labels and aluminium enclosures.
When I'm happiest I'll put up sound files.
Piet, you are a diamond.
Watch this space.

[dave robinson]

I'd be happy to help you with the demos Ecca, after all I won't be doing too much else the next six months . . . . . . . .

[ecca]

I was rather hoping you'd say that Dave. Let me 'mess around' with it a little more and you can have it to play with.
Yours sincerely,
'Gravy Stain Thacker.'

[ecca]

Right , I've had a last play around with it today, nothing fundamental, just re-arranging the order of pre-amps to see if there was any improvement but I have to say that the original arrangement was the best.
Valve pre-amp/ echo module/ valve post-amp.
The engraved front nameplates, the aluminium enclosures and the PCBs from China are all en-route so I'll be rolling soon.

[ecca]

Here's the finished Valve etap .
I know, I know, the colours are a bit loud but I'm more practical than artistic.
They're clear to see and it's obvious which one does what.
I've sold 2 and they're £195 each + P&P.
The sound is great, I've been taking the prototype to the Hankies club for weeks and it works fine.
There are 2 level controls, input and output, 2 separate valve preamps.
I've stuck with the thumbwheel because the other types are for PCB mounting and are too weedy for me.
The power supply is 12 volts AC, a suitable one from Maplin is Order Code: L54BR
Whaddya think ?
Ecca

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[Nick Allan]

Fantastic - can't wait !

Thanks Ecca,

All the best,

Nick

[ecca]

A good power supply is one from Maplin
http://www.maplin.co.uk/ac-ac-fixed-voltage-high-current-power-supplies-240

This is a list, don't get the 24 volt one, get the 12 volt ,Order Code: L54BR

[AlanMcKillop]

Looking good, I'll give you a call later.

[rogera]

Ecca I'm curious - if the power supply is 12 volts ac, is there a step up transformer to provide sufficient voltage for the valve anodes?

[ecca]

Yes Roger, the HT is around 210VDC.
I chose a low voltage to be safer.