50 Watt amplifier

[John Caswell]

Hi all,
I am beginning to like this thread!
Very nice amp Richard but if I brought that amp home death would follow swiftly.
My ladywife vented her spleen at a manufacturer at one Hi Fi show, when looking at the chrome and gold chassis she commented "Are to try to keep wifey at home polishing dust and finger marks off of it because he (me) won't do it"
WAF is very important I agree, as are aesthetics, but not at the cost of construction/performance. Perhaps I was lucky in wife choice (She would say so I hope)
It is also noticeable that the Matamp eschews what I stated earlier about cores at right angles and top mount txs. It could have been even neater if the smoothing caps had been fixed from under the chassis. Why gold plate the capacitor clips, I think that is aesthetics gone mad.
Also 'Drop-ins are popular as they only need one end cap" agreed "the wires are safely enclosed" but in fully shrouded uprights they are even more so.
I am not nit picking for the sake of it but to get people to think what they want and how they want it, and then we will see what comes out of all this

John

BTW. I commented on Loctal valves, Electronically a 12AX7 = 6SL7 = 7F7 and 12AU7 = 6SN7 = 7N7 according to my Sylvania book. Loctal valves are very underrated in my book so can be cheap.

[davebms]

John

BTW. I commented on Loctal valves, Electronically a 12AX7 = 6SL7 = 7F7 and 12AU7 = 6SN7 = 7N7 according to my Sylvania book. Loctal valves are very underrated in my book so can be cheap.[/quote]

hello all .. re loctal valves, i think it in MJ book, that the loctals are THE valve, the others were to make things smaller,(that my be b rozenblit)
re chassis i have worked on an amp with a deeper- top/bottom, that seemed to have more room to fit bits in. cage, that for sum is a must have ! or at least riv nuts so that a home made can be fitted

[John Caswell]

Hi Dave,
Yes MJ apparently loves them and they have many advantages, they were just around at the wrong time 'cos B9A based valves were coming in, and just like Nuvistors were at the advent of transistors. And of course people now swear by c3g and c3m (Loctals)

John

[Richard]

Going back to the 9 pin to octal converters John, all,

I checked mine yesterday and found the holes/tabs of the 9 pin sockets clash with the edges of the octal holes making a simple converter plate a bit tricky. I saw the tube town ones but then came across these which show how to overcome the problem neatly using countersunk screws.

I may use a 7 pin in mine as well and happily they will fit without problem on a plain piece of metal to convert the octal as they're smaller.

[John Caswell]

Hi Richard et al
Just looked at my Tube Town convertors an they appear to be the wrong size.
A B9A base requires a cutout of 3/4" dia with fixing centres of 1 1/8" so as you say Richard the fctrs will clash with the edges of a correct cutout of 1 1/8" for an octal base.
Yes, using a slightly thicker metal for the convertor would enable you to csk the B9A fixing screws. They of course could also be spaced away from the chassis by one M4 nut thickness which would allow the B9A M3 fixing screw heads clearance and also provide a bit of ventilation. This is probably the way I would go, but a good point raised!
As you say B7G aren't such a problem as the cutout is 5/8" dia and fctrs are 7/8".
Classic Parkinsons law X advantages = 2X disadvantages

John

[Baggy Trousers]

.

Originally Posted by Matthew Snell

"but frankly for a design first shown in Wireless World April 1957 I am seriously impressed."


Upright, surface mounted transformers and pierced metal cover anyone?

I'll report further when I've a better idea how viable this project might be.

Lovely project John, and thank you.

Matthew

Well, in my view, you could do a lot worse than copy the big Avantic - you're well on the way already.

And don't be so disparaging about Daimlers. After all, they were Britain's first sports car. Anyway, a Daimler KT88 would beat an MG KT66 . . . . .

[bob orbell]

Originally Posted by Baggy Trousers

.

Well, in my view, you could do a lot worse than copy the big Avantic - you're well on the way already.

And don't be so disparaging about Daimlers. After all, they were Britain's first sports car. Anyway, a Daimler KT88 would beat an MG KT66 . . . . .

Reading a past post of yours Baggo, do you remember that man who designed the Daimler V8 engine? long live Triumph twins, I love them. BOB vibrating back to happyness.

[John Caswell]

Hi all,
I do not want this thread to drift off subject, so can we please not get involved in Daimlers and Triumph twins.
If you want to write about those then use the "Coffee bar"

John

[Matthew Snell]

Well...

At a reasonable guess this amp could be produced as a kit for maybe £1600. That's for a pair of monoblocks, valve rectified - and not in a massively "shiny" spec. It would still look good - standard World Designs front panel, black powder coated chassis etc. - but (wanting to keep the price down) black transformer cover / mounts - and surface mounted!

XL components might push this up by £100 - £150 or more - but I'd want to launch a "standard" version first. Chromed transformer cover / mounts would have a big impact on the bottom line - but could readily be offered on a bespoke basis.

It's obvious that everyone wants something slightly different to everyone else! Can't be helped. The amp, though, is lovely and would complement the kit range very nicely. And (breadboarding aside) it could be seen as a bit of a bargain too.

Nothing set in stone - and some feedback would be appreciated... Anyone interested? Or know of someone who might be? I would need a good few "intentions to order" to move the project forward.

(And I think Daimlers are fantastic cars - just as I think the KT88 is a fantastic amp - I was just trying to put across some kind of Jilly Gooldenism. But let's not annoy John by talking about cars again! Or motorbikes! In this thread, anyway.)

Thanks - and let us know what you think.

Matthew

[bob orbell]

I think that price is very resonable for what seems a very good amp. the black transformer tops should be a nice touch too, after all, valves should not be to close to shiny things I read in Morgan Jones book. Sorry to John for taking the thread of track, can the posts in question be moved to the Coffee bar? or are we all forgiven . I for one will keep my WD KT88, but may be one day, who knows. BOB