Any reason not to put preamp filter caps on main board?

[yankeerob]

That's the point.
That's why they buy "Tweed Champs" filled with digital effects and PC CPUs wrapped in tolex labeled "Valvetronix", thinking they bought "Brian May's amp".
I do not like to give away good ideas for free to monster commercial makers, but the "cap vault" over the chassis is an excellent place to hide the hard disk, he he.

I'm not a fan of any of the above either I'm just saying there are virtues of both types of capacitor and as long as you've got the right design - either can be applied to a great audio device. Its more a case - as you well know - of how good your earthing scheme is anyway...

[JoeM]

I definitely second this. A dog house on top of the chassis is probably the single worst place for supply decoupling capacitors.
Here's how I do it when in the mood for PTP assembly, this system makes it easy to design a PCB later with almost identical component/wiring topology:

Nice! Did you have to cannabilize a Tek 545 for the ceramic strips? Silver content solder too?

[Alex/Tubewonder]

Nice! Did you have to cannabilize a Tek 545 for the ceramic strips? Silver content solder too?

You're kidding me, aren't you? Cannibalize a 545? Never. Strips are currently manufactured by Hescon Electronics GmbH in Germany. Really expensive (7 Euro/pc) but worth the price and the 4 blue Cambion teflon terminals weren't cheap either.

[JoeM]

You're kidding me, aren't you? Cannibalize a 545? Never. Strips are currently manufactured by Hescon Electronics GmbH in Germany. Really expensive (7 Euro/pc) but worth the price and the 4 blue Cambion teflon terminals weren't cheap either.

Excellent :~

[Russ]

Alex/tubewonder,

Very nice layout & wiring, but I noticed the ground busses seem to connected to the chassis in 2 places - ie at each end.
If what I see is correct, doesn't this form a loop, which in ground circuits, should be avoided?
Maybe better to connect the busses at a single point and then connect from that point to the chassis.

Russ

[Alex/Tubewonder]

Alex/tubewonder,

Very nice layout & wiring, but I noticed the ground busses seem to connected to the chassis in 2 places - ie at each end.
If what I see is correct, doesn't this form a loop, which in ground circuits, should be avoided?
Maybe better to connect the busses at a single point and then connect from that point to the chassis.

Russ

Russ, no ground loops. Ground and HV bus blue support terminals are isolated from the chassis. These withstand 5kV.You need to stick your head into the speaker cab to hear a faint hum residue burried in some white noise.

[loudthud]

Really excellent work Alex/Tubewonder!!

Originally Posted by JoeM
Nice! Did you have to cannabilize a Tek 545 for the ceramic strips? Silver content solder too?

To continue the Tektronix theme, you would have to sandblast the amp with walnut shell dust to remove the soldering flux. That's what they used at Tek before the widespread use of freon. Back on topic, those Tek 500 series scopes used a lot of multi-section can caps, a real pain if you want to get one of those things going again. There are those that obsess over those old scopes as much as we do over tube guitar amps

My preference is to have the filter caps on the main component board close to where they are needed.

[JoeM]

...To continue the Tektronix theme, you would have to sandblast the amp with walnut shell dust to remove the soldering flux. That's what they used at Tek before the widespread use of freon. Back on topic, those Tek 500 series scopes used a lot of multi-section can caps, a real pain if you want to get one of those things going again. There are those that obsess over those old scopes as much as we do over tube guitar amps

Very interesting.

Yeah, there's Tek Scope group on Yahoo, and they do obsess over these. One retired Tek engineer has a collection of over 500 Tek Instruments. Very helpful guy though if you need help getting one running again.

[guitarmike2107]

Alex, what is that clear tubing you have used for the insulation and where did you get it, some of that might be handle for a build I am doing now. I have been stripping insualtion off wire but if I can buy it that would be better.

thanks

Mike

[Alex/Tubewonder]

Alex, what is that clear tubing you have used for the insulation and where did you get it, some of that might be handle for a build I am doing now. I have been stripping insualtion off wire but if I can buy it that would be better.

thanks

Mike

Got it from Elfa, they'll ship to anywhere in EU. It's PTFE insulating sleeve/tube, all major suppliers of electronic components and cabling materials should have this stuff.

[yankeerob]

You're kidding me, aren't you? Cannibalize a 545? Never. Strips are currently manufactured by Hescon Electronics GmbH in Germany. Really expensive (7 Euro/pc) but worth the price and the 4 blue Cambion teflon terminals weren't cheap either.

Why is it things like that are so expensive... is it because they know guys like us NEED clever stuff like that... Wondering if you'd divulge the source (if it's a distributor you get them from) of such items... vey interesting stuff indeed

[Alex/Tubewonder]

Why is it things like that are so expensive... is it because they know guys like us NEED clever stuff like that... Wondering if you'd divulge the source (if it's a distributor you get them from) of such items... vey interesting stuff indeed

I bought ceramic strips directly from manufacturer in Germany: HESCON eletronics GmbH
IIRC they have a minimum order value of 50 Euro. No on-line shop, you need to email and ask for quote on items from the catalogue.
Cambion terminals are manufactured in UK and are available from Farnell/Newark.

[Gregg]

I personally design all of amps with the entire power supply at the power transformer end which - as good design would have it - is furthest away from the input.

+1
I always use radial caps.

Got it from Elfa, they'll ship to anywhere in EU

Probably the most expensive online shop in EU.

[überfuzz]

I replaced filter caps on an amp that had these caps on the main board. They were not stuck and they were over sized, very much so, so I had to unmount the whole board to get them out. I remember thinking why so big and if only the filter caps had been on a separate board.

Not a problem caused by the design it self, but an other design would have eased the unmounting... I guess.

[yankeerob]

That's my point entirely...

To say you should do it either way is moot... as long as you use good caps it won't matter how long your PS wires are (within reason of course) as long as you use good wire and use your beenie when it comes to lead dress...

I'm just finishing up a recap on a SF Bassman 100... nice amp... shame about the lead dress!!! But I've shaped it pretty good, new bias and screen gid stoppers, those carbon comps had to go... I know that was what was available at the time but geez... right on an inverted tube base... it'd been hacked about a bit but not too bad... All new F&T 105° electrolytics (had the original Mallory's... yikes!!)

Any road - my amps are built with tech's in mind - that way they'll be around for as long as possible - most amp mftr's don't care about that anymore!!