Component Placement

[tubehunter]

Hi,
I need abit of advice about component placement on an el84 monobloc valve amp i'm building.
Here is a computerized image i've created which shows the way i think would be ok.



not sure about this flux leakage i've heard about.
I've already built the cases to match the valve dac/pre so can't change the base.



tia

Duncan

[aquapiranha]

Hi Duncan, that looks great! and a bit like the Decware EL84 amp I have at the moment, but with a difference of course being that the decware is stereo. Can I ask, I presume this is your own circuit design? do you have any expected specs? Thanks.

Oh, and what s/ware did you use to make the image????

[tubehunter]

Hi,

Spec:
Class A 15W per amp into an 8ohm load.
Frequency response 17Hz to 30KHz
Input sensitivity 380mV, might change this depending on the preamp.
Simulated in Multisim 9

Description:
This configuation has been used very successfully in other designs, one I built but which had a shared power supply was good but limited its channel separation capability somewhat.

The power supply was designed using PSU Designer II, which is a great piece of software.
Power supply uses a EZ81 rectified with capacitor input then choke.
First stage is the pentode section of a ECF80. This is used for voltage gain.
Second stage, the triode section of the ECF80, is used as a phase splitter in Concertina format.
Then onto the output stage which is the classic push pull using EL84Ms

Parts:
VVT mains transformers
VVT choke
EZ81 rectifier tube JJ
Input capacitors Obbligato PSU Film 47uF 500V
further smoothing Obbligato PSU Film 47uF 500V
then rc voltage drop Obbligato PSU Film 100uF 500V though I might regulate here.
ECF80 Mullard tube
Welwyn 1% resistors throughout
Ampohm paper in oil DC blocking/coupling capacitors
Blackgate electrolytic cathode bypass capacitors
EL84M Russian military output tubes
Custom wound Sowter output transformers with 20% taps

The image was created using PTC ProDesktop2000i, I find this software very easy to use and you can have a design finished very quickly. It also dimensions everything automatically so you have a template to use for cutting the cases.

Duncan

[aquapiranha]

Thanks Duncan. You so obviously know what you are talking about, and haing heard one or two items you have produced can honestly say they sound boody brilliant, no brainers really.

[tubehunter]

Finally got the transformers.

Why is there such a long wait for things in this country?



All I've got to do is cut the case and wire it up!

[Marco]

Looks very naughty, Dunc!

Are you sure you couldn't have over-spec'd it even more?

Looking forward to hearing the results when you bring it round to Ian's

Marco.

[Ian Walker]

WELL GET CRACKIN THEN


....can i light the fireworks?......

[leo]

Looking well smart Duncan!

I remember having to wait what seemed forever for a pair of Sowter output transformers for my KIT88

[John]

Looking really good Duncan if itas good as the DAC/PRE you will have something very special

[Spectral Morn]

Finally got the transformers.

Why is there such a long wait for things in this country?



All I've got to do is cut the case and wire it up!

Wow respect is due. That looks amazing.

When Steve(aquapiranha) visited me recently he was telling me all about the amazing Dac-Pre you made and which Ian Walker got as a replacement for a certain well like Japanese Dac S---. All I can say not having heard one of your designs is double WOW. That is testament indeed to how good you must be at building and designing. I look forward to your write up of this amp when finished.


Regards D S D L