Copper time again

[tubehunter]

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/IMG_5966cropped.jpg

[brian2957]

Looks fantastic , work of art .

[Alex_UK]

A pair of monoblocs, Duncan? (You little tease! ;))

[valves]

If only I could build something like this.

Is it possible for a novice?

Carl.

[realysm42]

I don't know what they are, but they are very pretty I don't know what they ares.

[StanleyB]

Rectifier diode valve, single valve driver stage, push pull valve output stage. Transformer output.

[realysm42]

Oh, I see that now!

[Roy S]

round things go in the round holes, rectangular things go in the rectangular holes, square things (I'm bored now - did I pass?)

[tubehunter]

yes, all correct

The transformers came today, the house smells of baked varnish:)

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/IMG_5969.jpg

[Rare Bird]

Who did the metalwork Duncan if you don't mind me asking?

[tubehunter]

Hi Andre,

I do all my own.

I'm lucky as I have access to engineering workshops while at work.
1000mm X 600mm 14 gauge copper sheet from Merseyside Metals at around £95.

Still tough going, coping saw and files.:(

[Rare Bird]

It's the metal folding i was intrested in but if you have access to engineering shop you'll probably have metal former

[Jonboy]

Those will match my (your) dac very well Duncan ;):)

[Alex_UK]

Ooh - Jon - "suits you Sir"? Are you the lucky owner? :drool: (The drool was for the amps, by the way, not you! ;))

[tubehunter]

These I'll be keeping for this for a while;)

just to show some scale...

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/IMG_5978.jpg

I'm waiting on a pair of replacement mains transformers, the original order had a misshap and were cooked too long.
The one fitted was marginal the other was a right off.

[Ali Tait]

EL84 amp Duncan?

[tubehunter]

Yes,
I really like the EL84.

[Jonboy]

Yes,
I really like the EL84.

Me two, so musical and bereft of coloration

[Ali Tait]

Yes, it's a nice little valve.

[Ali Tait]

What circuit are you using Duncan?

[tubehunter]

Hi Ali,


There are four possibles uptil now:

Morgan Jones 'Bevois Valley'

Gary Devon 'Kel84'

Gingertube 'Baby Huey'

Mullards '5-10'

I really like the concertina phase splitter of the first two.
The Baby Huey I find interesting but haven't heard.
The Mullard is a classic but I'll need to add another socket, no problem.
Then the Leak designs are a possibility.

Prehaps a vote might be in order...

[Ali Tait]

This is supposed to be good if you can live with the limited power -

http://home.comcast.net/~jafix/SakumaEL84.html

Sakuma San's EL84 driving EL84.

I've also read good things about the Simple EL84 -

http://diyparadise.com/simpleel84.html

[howlindawg]

Ultra neat DIY. I love it!

[tubehunter]

Interesting Ali I've not seen those circuits.

But the output transformers are push pull with 20% and 43% taps for ultralinear modes. Not suitable for single ended use.

I'm drawn to this circuit, fully class A.
http://diyaudioprojects.com/Tubes/EL84-Push-Pull-Tube-Amp/

Yes howlindawg, I designed the chassis to have the smallest form to keep wiring short.

[anthonyTD]

hi Duncan,
yes, that circuit should work well with the current source in place,otherwise not realy, and only in class A [of sorts]
And as stated, it allows the minimum of valves, parts etc for a good little push-pull design.
Anthony,TD...

[tubehunter]

Yes it was the constant current source that attracted me.

As I'm building new amps I thought I might as well go for a phono/pre as well.:)


http://i514.photobucket.com/albums/t350/halx00/el84%20monos/IMG_5981.jpg

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/IMG_5980.jpg

[anthonyTD]

Nice...
but then i am biased,:eyebrows: copper being my favourite out of all metals.
Very nicely done.:)
Anthony,TD.

[Ali Tait]

Yes indeed, Lovely job Duncan.

[DSJR]

They are absolutely gorgeous, a credit to you and I hope the new owner will cherish them once completed...

A little copper phono stage would be well worth having (Stop Dave, STOP!!!!!!!!!!!!!!! :lol:)

[tubehunter]

Thanks for all the good vibes.
Replacement mains transformers arrived today and made some good progress .

Could be finished by Christmas:)


Organised choas

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/IMG_5982.jpg

[Jonboy]

Keep the pics coming Duncan, looking really good :)

[howlindawg]

Duncan,

What are you using to prevent the copper from tarnishing?

[tubehunter]

I don't finish the copper.
I like when it darkens down abit to be honest, if you like the polished look it's the brasso and a cloth every now and again.

Well 8 hours later and I have the power supply sorted and heaters wired.
The tagboards are ready so not long now.

My eyesight isn't what it used to be.:(

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/IMG_5983.jpg

[Reid Malenfant]

Nice work, & coming together at a real rate of knots to :D

[tubehunter]

Well I've finished them off.

Sound really nice, the valve amps I've had before have all been stereo amps with a single shared power supply. I knew going to mono blocks would open up soundstage and doesn't it just.:)

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/IMG_5989.jpg

Now to finish the Phono/Pre.

[Jonboy]

you certainly don't hang about, what circuit did you decide on in the end Duncan ?

[tubehunter]

These are settling down nicely. Fantastic 3d sound with such delicacy then slam, I've got to recommend the Vvt transformers great job.:thumbsup:

The circuit I ended up with was an assortment of the Kel84 front end (only because I have plenty of ECF80 valves and I do like that phase splitter) with Mullard ouput stage but with lower loading to achieve lower distortion.

The power supply is mainly Mullard but I've used a good sized choke where they don't, and the second pair of capacitors are of larger values. I used PSU Designer II here, great piece of software.

I used AC heaters throughout and the amps are very quite, so no solid state in there at all.

I like them a lot so I'm going to build another pair next month to use upstairs on the PC.
Or I could bi-amp or go active....:eek:

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/IMG_5994.jpg

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/IMG_5997.jpg

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/IMG_5995.jpg

[tubehunter]

Prodesktop render of the next amp.

Can't decide on the layout, it's a dual mono amp with only the mains lead shared.

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/valveamplayoutdaylight.jpg

or this

http://i514.photobucket.com/albums/t350/halx00/el84%20monos/valveamplayout2.jpg

[Ali Tait]

I prefer the top one.

[Butuz]

Sorry to not read entire thread. Where do you get the copper chassis from?

Cheers

Butuz

[bobbasrah]

I prefer the top one.

:lol: