Stereo valve amplifier

[learner pianist]

Hello to all,
I am looking for info. on building a stereo valve amp. I have noted that various kits are available-but all seem very expensive. Is there any info on circuit diagrams, build details, parts lists, etc. I last built an amp in about 1958, and I wish for a winter project. Any info on parts suppliers? Also, what about valves-are these still available. All advice gratefully accepted.
Thanks in advance.
learner pianist

[Aerodyne]

Hello and welcome to the forum
I' presently working on a stereo amp using 6V6s in push-pull, based on modified vMullard circuitry. I'd recommend you start with Mullard or one of the classic designs - GEC, for example. As long as you don't want silly amounts of power output, the requisite valves shouldn't break the bank.
I personally would never build one of the modern kits. Far more fun and satisfaction on building from the ground up. A matter of choice, really. Any valve amplifier is going to be expensive, much of the cost being the transformers. As for suppliers, search the internet. For wound components, look up VVT. For other parts, try Bitsbox, ESR, even Maplin for some odds and ends. Ebay has valves but often at a premium. You should shop around - try Sequoia, Chelmer, Watford etc.
Others will offer other alternatives, I feel sure. Good luck.
-Tony

[Peter.N.]

I would agree with Tony, build a good old fashioned amplifier, very simple and basic but work well. I used to build amps in the '50s usually using a couple 6V6's, EL33's or when I got a bit better off, KT66's, using 6SN7's or similar as drivers/phase splitters, I could probably draw you a circuit off the top of my head - but mind you, that's about all I can remember.

Peter

[G8HQP Dave]

All the parts you need are still available. These days the hardest to find can be the chassis.

I would recommend one of the Mullard designs: 3-3 or 5-10. Google will help you.

[Skywave]

Ah, yes - the chassis! Don't forget the good old D-I-Y stand-by of a square steel cake tin or a deep rectangular oven-baking tray.

Al. / Skywave.

[percival007]

I can't agree more with what has been suggested above.

I myself started with the Mullard 3-3
http://www.r-type.org/static/3-3.htm

and am extremely pleased with it. That is actually something of an understatement really, it is now my current Amplifier, used every day and i never cease to be amazed at the quality of those ''3 Watts''! Deceptively loud with relatively 'ordinary' speakers.

The valves used (EF86, EL84 and EZ80) are very easily found and the EF86 and EL84 are still being manufactured. I am uncertain about the EZ80 but its slightly bigger brother, the EZ81 is. Just be aware that it has slightly different characteristics, but with the right transformer (especially regarding the Heaters) can be used instead of the EZ80 without any re-wiring.

This Amp:-
http://www.r-type.org/static/2-3.htm
is even easier to make and only uses one valve per channel but beware, the ECL86 i don't think is made these days so would have to be sourced second hand.

As has been said above, for Transformers VVT are excellent. I have no affiliation with the company other than being a very satisfied customer. Thier customer service i found to be second to none. I needed a 'modification' to one of thier 'off the shelf' versions (a second Heater supply at 5Volts rather than the 6.3Volts as specified on thier site) and this was accomodated without any problems, some of my emails being answered on a Sunday!

For chassis' or boxes i have used HiFi2000
http://www.hifi2000.it/default.asp?Langid=1
I think they are very reasonable for what you actually get. Of course as has been already said, an upturned biscuit tin will work equally well and will look the part with a coat of paint and will be considerably cheaper!

Besides the link to the 3-3 i have given, do search this Forum for the 3-3, there are plenty of others on here who have built one and there is a wealth of friendly advice and information to be had from people on here.

Best of luck,

James.

[Trevor]

look up lola
this is an amplifier i presented to the forum earlier she is easy to build and low cost for a valve unit
regards trevor

[Mike Phelan]

Another vote from me for the 3-3. Its simplicity belies its performance.

It was the first stereo system I made in the 1960s and used it for a long while.

the ECL86 i don't think is made these days

or use the PCL86 (10 NOS for 16 quid on ebay), very cheap, needs a different heater voltage, a small torroidal transformer could easily supply two in series or parallel.

[Aerodyne]

In the early days I built one of the Mullard 7 watt stereo designs, using ECL82s. I was pleased with its performance and when I found the ECL86 version - uprated of course, watts wise - I semi-considered building one until I realised the cost of ECL86 valves. I think that the Mullard designs provide a good basis for building on - modifying to suit your own preferences and needs regarding tone control, input sensitivity etc. and I'm very pleased that others agree with me regarding the quality of those designs.
-Tony

[trickie_dickie]

How about this.....http://electra-print.com/el84psapp.php

Obviously , you could use different make of transformers.

[gulfstream]

Hello.

This is a nice sounding, cheap and easy to build SE amp with
available pcb, lots of info and modification/upgrades.
6T9 tube deliver nice sound for the bucks you pay for it.
I did build two of them for my friends.

http://diyaudioprojects.com/Tubes/6T9-Tube-Amp-Kit/

Good Luck!
von vulpes

[Billy T]

Originally Posted by percival007

The valves used (EF86, EL84 and EZ80) are very easily found and the EF86 and EL84 are still being manufactured. I am uncertain about the EZ80 but its slightly bigger brother, the EZ81 is. Just be aware that it has slightly different characteristics, but with the right transformer (especially regarding the Heaters) can be used instead of the EZ80 without any re-wiring.

The only parameter you need to worry about is the filament current capacity of your power transformer. The EZ81 needs an additional 400mA, which might push a marginally-specced power tranny into overload. Most transformers of quality manufacture would stand that without trouble though.

Cheers

Billy

[Biggles]

With regards to larger chassis construction I have seen three aluminium boxes bolted together with a top sheet added to cover the joins used succesfully. The three seperate units can also provide extra screening between say the psu and audio stages. I use off the shelf (Maplin) aluminium boxes approx 12"x6"x2" for smaller project chassis although they are a little bit awkward because everything has to be built into the lid of the box. I'm not sure if Maplin still sell mains and output transformers too.
Alan.

[Herald1360]

Wouldn't it be easier to use the base like a chassis then drop it into the top now used as a bottom cover?

Or with a bit of flat sheet and enterprise, you get two chassis for the price of one......

[murphyv310]

I Know it was referred to a few posts back but I would put my money on the Mullard 3-3 amp.
It's a beautiful little amp, with superb audio quality and with efficient speakers more than adequate volume.

[Biggles]

I dare say it could be Herald, but the finished product doesn't look as neat, due to the design of the folds. In reality it's not a problem being upside down, as when the box is finally put together it gains a lot more strength.
Alan.

[Sideband]

I'll also put in a vote for the 3-3. Built a couple over 40 years ago and they were superb. Ended up being the main source of general entertainment throughout the 70's and it was passed on to friends later when I replaced it with a couple of 5-10's


SB

[davep49]

For the complete mullard amplifier book try this (broadband connection only!):

http://www.vvttransformers.co.uk/drb...b12919_dhn.htm

[bluepilot]

Kits may seem expensive but I suspect only because you are buying all the components at the same time. If you buy everything separately then the individual items may seem cheap, but by the time you add them all up plus the postage then it can well end up expensive. I discovered Ebay article 170591573314 which seemed to be reasonably priced to me considering it includes everything. Of course you may prefer to bend and drill the chassis yourself, but winter won't last for ever