Building my own valve amp
 

Hi guys,

I am planning on building my own valve amp and need a starting point
viz. books, forums etc. Any tips would be of good help.


I have proved to myself that I can solder well and don't have shakey
hands and did EE in my previous life.


Cheer Max.

Building my own valve amp
 

On 30 Oct 2007 09:15:42 -0700, max graff wrote:

Hi guys,

I am planning on building my own valve amp and need a starting point
viz. books, forums etc. Any tips would be of good help.


I have proved to myself that I can solder well and don't have shakey
hands and did EE in my previous life.

You want to build it or design it?

Building my own valve amp
 

"max graff" wrote in message
oups.com...
Hi guys,

I am planning on building my own valve amp and need a starting point
viz. books, forums etc. Any tips would be of good help.


I have proved to myself that I can solder well and don't have shakey
hands and did EE in my previous life.


Cheer Max.


If you want to build an amp from scratch, I recommend the Mullard Book of
Audio Circuits, which includes the 5-10 and 5-20 amplifiers together with
the 2 valve and 3 valve pre-amps. They have full circuit and constructional
plans, and you can't really go wrong.

The power amps are fine, if a little low-powered for most of today's
loudspeakers, but the pre-amps are rather noisy, and you can do better with
a modern SS design. Having said that, if you know your way round circuits,
you can delete the tone-control stage and have a passive pre-amp with active
RIAA stage. The input sensitivity of the Mullard amps is something like
70mV, so a passive controller will work fine.

If you want more power, the GEC amplifier book has high quality designs up
to 100 watts, and PA style designs up to 1 kW. They don't have full
constructional details like the Mullard book, but are fine for the
experienced constructor who can work out chassis and point-point wiring
layouts.

S.



--
http://audiopages.googlepages.com

Building my own valve amp
 

max graff wrote:
Hi guys,

I am planning on building my own valve amp and need a starting point
viz. books, forums etc. Any tips would be of good help.


I have proved to myself that I can solder well and don't have shakey
hands and did EE in my previous life.


Cheer Max.


Given your previous life, I don't know of a better place to start than
Valve Amplifiers by Morgan Jones, you can find it on Amazon.

Loads of forums, mostly US based though.

--
Nick

Building my own valve amp
 

On Tue, 30 Oct 2007 09:15:42 -0700, max graff wrote:

Hi guys,

I am planning on building my own valve amp and need a starting point
viz. books, forums etc. Any tips would be of good help.


I have proved to myself that I can solder well and don't have shakey
hands and did EE in my previous life.



Read, read, read...

TAKE NOTE OF THE SAFETY ISSUES. HIGH VOLTAGES CAN KILL YOU.

Unless you are building a kit (not a bad place to start) you are going to
have to know how to choose the necessary bits to build it. Even if you
find a design that you like, there is every chance that some of the
components that are specified are either no longer available or only
available in the US, with accompanying high carriage charges. That
results in having to source near equivalents - not easy in some cases.

You have to remember that in a valve amp all the components are
interrelated. You need to have the valves operating in about the right
region of their curves to get anything like what the design says. That
means that you need the right HT (or B+ for the foreigners), the right
output transformer, the right cathode resistor(s) and the right input
voltage swing from the previous stage to start with. Get any of those
wrong and you're off to a poor start. That means that you need to be able
to draw a load line and read data from it - so there's no getting away
from that reading...

Having said all that, you can have a lot of fun designing an amp on the
breadboard; fiddling the bias while watching test tones on a 'scope until
you find a setting that you like. It needs a bit of test gear, but it's
never wasted. You can get a really good insight into how valves and amps
work that way.

Have a clear idea of what you want before you start.

Don't buy *anything* until you are pretty sure that it will all go
together!

Remember that the one item that makes or breaks an amp is/are the output
transformer(s). Use junk and you can never get top quality sound.

Remember that (particularly for a single-ended amp) the output stage is
just a way of modulating the power supply. If the power supply is poor
you get hum, low output, distortion etc. etc. Good quality chokes and
capacitors will repay their cost in sound quality.

My own recommendation would be to build a simple single-ended amp, with
1/2 an ECC88 for the input stage (it looks like a good driver to me) and
an EL34 triode-connected output stage. All those valves are commonly
available and quite cheap. It won't be very sensitive and only low power,
giving about 6W max from a CD player input. That isn't too bad if you
have fairly sensitive speakers. I don't know if that would do for you,
but IMHO it would be a good beginner's amp. It should sound very nice too.
Something a bit like this:
http://www.angela.com/catalog/how-to/SE.EL34.html You can get those
transformers in the UK. I would like to try the ECC88, perhaps with an
LED instead of the cathode resistor/capacitor instead of the 6SL7 though.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info http://mixpix.batcave.net

Building my own valve amp
 

mick wrote:

On Tue, 30 Oct 2007 09:15:42 -0700, max graff wrote:


Hi guys,

I am planning on building my own valve amp and need a starting point
viz. books, forums etc. Any tips would be of good help.


I have proved to myself that I can solder well and don't have shakey
hands and did EE in my previous life.




Read, read, read...

TAKE NOTE OF THE SAFETY ISSUES. HIGH VOLTAGES CAN KILL YOU.

Unless you are building a kit (not a bad place to start) you are going to
have to know how to choose the necessary bits to build it. Even if you
find a design that you like, there is every chance that some of the
components that are specified are either no longer available or only
available in the US, with accompanying high carriage charges. That
results in having to source near equivalents - not easy in some cases.

(extra good, but rather specific stuff given the original question snipped)

Yep, or just read a copy of MJ.

--
Nick

Building my own valve amp
 

"max graff" wrote in message
oups.com...
Hi guys,

I am planning on building my own valve amp and need a starting point
viz. books, forums etc. Any tips would be of good help.

**Just listen to a bunch of amps in your price range. Buy or build the one
you like. Just for yuks, see if you can organise a blind test of the amps.
That orta sort out the dodgy ones. For valve amps, unless you build it
PRECISELY the way you hear it (same valves, same output transformers, etc)
you will be wasting your time.


Trevor Wilson

Building my own valve amp
 

"Trevor Wilson" wrote in message
...

"max graff" wrote in message
oups.com...
Hi guys,

I am planning on building my own valve amp and need a starting point
viz. books, forums etc. Any tips would be of good help.

**Just listen to a bunch of amps in your price range. Buy or build the
one you like. Just for yuks, see if you can organise a blind test of
the amps. That orta sort out the dodgy ones. For valve amps, unless
you build it PRECISELY the way you hear it (same valves, same output
transformers, etc) you will be wasting your time.


More totally stupid *advice* from Trevor...

For a kick-off, how TF do you suggest he goes about organising the
test - ask 'Valve Amps R Us' if he can play with half their stock for a
few hours then, having picked one (real easy), ask them for a circuit
diagram and a parts list for it...??

Building my own valve amp
 

"max graff" wrote in message
oups.com...
Hi guys,

I am planning on building my own valve amp and need a starting point
viz. books, forums etc. Any tips would be of good help.


I have proved to myself that I can solder well and don't have shakey
hands and did EE in my previous life.


You have been recommended to read Morgan Jones - I have a remarkably
*unthumbed* 'Valve amplifiers' and 'Building Valve Amplifiers' here you
can have for about half Amazon prices + a couple of quid towards
postage, if you want them!

:-)

Building my own valve amp
 

Quite a few of us started out by repairing our old Leak Stereo 20s and
the like. It's still a great road into amp building. for a first step
I'd do exactly that - buy a Leak Stereo 20 and upgrade it with modern
componants. It's all point to point wiring and totally accessible.
Plus you have the leak group as backing to talk you through it. Morgan
Jones even has a suggested circuit for it in his Valve Amplifiers,
which you absolutely must buy. (that's an order!!!)

I think to date I've been through about 30 different circuits in my
Leak Stereo 20!!!