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Old 28th September 2012, 08:06 PM   #31
shanx is offline shanx  Canada
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Quote:
Anybody ever use a HI-FI output transformer for a guitar amp? What were the results?
Yes Hi Fi audio transformers are possible and have been used in production guitar amps. It will change the sound, so that is totally subjective. That Edcor is quite interesting, for the money. Hammond classic series is a good choice. I trust what Struth had to say about MM, although never dealt with them. I was wondering about Classic Tone series by Magnetic Components..maybe somebody has used them?
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Old 28th September 2012, 08:22 PM   #32
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Do those resistors between the screens do anything, or are they just to isloate the two tubes somewhat and maybe protect the other if one shorts?
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Old 29th September 2012, 12:37 AM   #33
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Quote:
Originally Posted by Struth View Post
Hi Guys
Have fun
Kevin O'Connor
londonpower.com
We need to talk. Your stuff is not cheap, but it would save me a lot of time and trouble. I tried to call but the time difference problem...I'm in California.

Your stuff is more what I had in mind instead of a Mercury Magnetics upgrade power transformer. First stiff, filtered, maybe even regulated supplys. Then add sag as desired where desired. Clean & quiet.

Some of your prices seem reasonable, not for the parts but for the time it saves me and guaranteed performance...other prices less-so.

Lots of decisions now that you make options easy, just still expensive.

I may need to get your books just to figure out exactly how your products work. But at least they seem to make sense from an electronics engineering viewpoint.

Last edited by cyclecamper; 29th September 2012 at 12:51 AM.
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Old 30th September 2012, 03:02 PM   #34
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Baby steps. I went to the steel yard and had them shear a sheet of 1/8" aluminum. So now I have a decent bottom for the amp chassis. I don't understand why guitar amp chassis that mount in a wood cabinet always seem to have one side open facing wood. Bad enough it's not fully shielded, but I'm amazed that UL would allow such high-voltage and high currents in such close proximity to wood; I'd expect them to require an all-metal enclosure. I also drilled 7 small holes to line ups with the end os the tubes, so that air can exit near their tips like the back vents allow. None neat the socket ends, or that would ruin the airflow design. I'll drill larger matching holes in the bottom of the new wooded case, or maybe I'll get two vent covers like on the top of some Vox amps and put them on the bottom.
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Old 30th September 2012, 05:50 PM   #35
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Wow, lots of typos in that post.
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Old 30th September 2012, 06:24 PM   #36
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Quote:
Originally Posted by cyclecamper View Post
I'm amazed that UL would allow such high-voltage and high currents in such close proximity to wood; I'd expect them to require an all-metal enclosure.
We just had a thread about that:
Building power electronics into a wooden cabinet?

Basically, metal is conductive, wood isn't, so wood wins for electrical safety. Metal also conducts heat, so there's no gain from a fire-safety point of view.

But shielding, yeh, that's a concern, and much more so these days than when guitar amps took their classic form.
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Old 1st October 2012, 04:09 PM   #37
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I'll go take a look there.

I had a power resistor get hot enough to unsolder its own leads, and drip hot solder. Seems to me if the bottom had been wood it would smolder quite some time. The fact metal conducts heat doesn't negate the fact it's nearly non-flammable. A metal enclosure can trip a breaker or fuse. Metal grounded by a 3-prong plug in a properly wired outlet beats wood for electrical safety (as long as the outlet really is grounded).
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Old 2nd October 2012, 09:19 AM   #38
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I just read http://www.valvewizard.co.uk/Common_Gain_Stage.pdf
Good reading.
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Old 9th October 2012, 05:28 PM   #39
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Just waiting for the transformer and choke. They build-to-order so apparently it can take a LONG time.

Meanwhile, as several advised, I like the Classic 50 much more now, because I also got an old Fender chassis to rework. That gets its own thread.
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Old 17th October 2012, 07:57 PM   #40
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Still waiting for that output transformer to be made and delivered. Still waiting for the larger reverb tank to be delivered.

Meanwhile, as an alternative to the Mercury Magnetics upgrade power transformer, I've started to consider adapting the replacement power transformer meant for a Peavey Classic 100 head w/ 8 EL84's to use in the Peavey Classic 50 with 4 EL84's. The preamp appears to be identical, and I imagine at most a few resistors might be needed for the transplant. But quite honestly, until I get the new output tranny installed and beef up the filter caps a bit, it doesn't really need a bigger power transformer (except it gets pretty hot when I play bass thru it for extended periods, and now I picked up a better bass amp). If I really need the Peavey Classic 100 power transformer and a bigger output transformer perhaps I should have just kept an eye out for a used Peavey Classic 100 head instead of beefing up the classic 50. But I didn't even know there was such a thing as a Peavey Classic 100. But the sound of the 50 is starting to grow on me, and I find myself using half-power (only 2 EL84's).
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