The Amp Garage

Yes - I am he

Big thanks on the switches!! Now, anyone have Ideas on the perf board? Well, I didn't chime in on this because you're all in such a hurry to clone Fran :) ... but I'll eventually have new stock of repro perf board (the original stuff is long gone). I reckon it's about a week or two away. See www.am...

Allynmey wrote:Omar CD sent...250 MB of beauty!

Allynmey

OHMYDOG! Best throw some more coal on the burner before making that little lot downloadable

Yes I did one (in a donor test-bed chassis - an old WEM). But I didn't follow the schematic rigorously. I kept the WEM iron, the EZ81 rectifier, and I can't for the life of me remember what I did about that PS resistor :oops: It's on my list of builds to tweak - there were a few issues (where the ga...

I've done one quick-n-dirty semi-clone and that also had very little headroom. Cleaned up very well though. I changed preamp valves to little effect. The plan for my second (a proper Express clone) is to try a dual pot, where the second element sits between the 3rd stage and PI. I reckon I'll have t...

I think I smell a spam-flavoured 'bot

Hope I'm wrong and that I get to apologise to a real person, who's actually interested in amps...

Hey Snapcase - thanks for bumping this thread - I missed Dai's last posting!

Dai - thanks for sharing all of that stuff. Looks like I've got some reading to do

If those are not there and there is no center tap the Winding won't make any voltage. EMF (Voltage) is always a potential, Now I'm the first to admit that I'm 'theory-lite' :) but that's wrong - surely? The potential difference is developed between the two ends of the winding, and the valves' heate...

OIC. Yup, if they're joined together, and not in-line with the heater supply, it's a "sort-of centre tap". Might be connected directly to ground, or elevated above ground (e.g. to power valves' cathode on cathode-bias amps, or some B+ voltage divider on other amps).

A band-aid fix for a slightly out-of-spec PT? Can't see the harm in it - just a tad more heat in the chassis. I've got a PT that gives about 6.9V when used in low power amps.

> most 50 watt marshalls put out around 36 watts and
> most 100 watt put out around 68 watts(before distortion of course)

Really? The official test figures are 115W RMS at the onset of clipping for the 100Wer, with 170W at 10% THD (into 4 ohms).

Interesting point about seemingly random grounding working like a sort of ground plane. I'm not familiar enough with PCBs to understand the role it plays. This is fascinating stuff. I am going to redo one of my simpler amps using as many of the ideas in this paper as possible. It'll change the layou...

Hey Dai - have you built anything using these grounding principles? I've now digested this info, and it's really useful. But it seems to me that 99% of commercial and homebrew amp layouts (well for guitar anyway) do not stick to these principles.

since that page is only in Japanese (and machine translations usually suck!). You can say that again. When I went e-shopping for Tokais on J-guitar I used translation software for the pages. I was alarmed to see "Fell Nun Death" and other weird things everywhere. :shock: I found out later that it w...

Wow Dai - I really appreciate your efforts (and Mr Kimura's). That's definitely one to print-and-keep in the theory file. I've only got about a quarter of the way through it and I'm learning lots.

I can't believe that was a "quick translation"! Thanks for sharing