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Topic: evans amp question |
Kevin Rickert
From:
Tennessee, USA
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Posted 8 Jan 2022 8:29 am |
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I have a few evans lvfet500 amps. the one I gig with is an 84 and to my ears is better sounding than my 87 model. Only difference I can tell is that the 84 unlike any other evans I've seen doesn't have the two blue capacitors (I think thats what they are). Just curious what they are and any difference in the amps with them.
Thanks for any input |
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Marty Broussard
From:
Broussard, Louisiana, USA
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Posted 8 Jan 2022 6:31 pm
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Wish I could intelligently contribute, but I am watching. I have 2 other identical amps with the exact difference/question. Hoping someone can unlock the mystery.
_________________
RETIRED
"Technique is really the elimination of the unnecessary..it is a constant effort to avoid any personal impediment or obstacle to achieve the smooth flow of energy and intent" Yehudi Menuhin |
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Eric OHara
From:
Port Kent, NY
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Posted 9 Jan 2022 6:50 am
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Call Scott at Evans. He’ll know for sure. Great guy and super helpful. Eric
_________________
GFI S-10 Ultra (GFI II pickup)
Sho-Bud Super Pro (wood necks) w/BL Pickups
RQ Jones Retrofit
Beard Decophonic 57/ Fishman JD preamp
Goodrich 6122-R
Walrus Slotva Reverb, JHS Thunderbolt, ZVEX fuzz factory
Evans JE-200, RE-150
Peavey Nashville 112, 400
Keal Cases |
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Jim Pitman
From:
Waterbury Ctr. VT 05677 USA
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Posted 11 Jan 2022 2:10 pm
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I now have two older session 400s and right off noticed differences in the tones. My original is a 1976 and the one I just acquired is a 1975 model
I had recapped my original based on the Sarno recession info he posted years ago so I decided to do the same with the more recent acquisition. It did make a difference yet still they weren't exact.
Being an EE, I set up a two channel o-scope and ran my frequency generator into both amps with the same signal while monitoring both amp outputs with the o-scope at the same time. I can dial in frequencies from 50 hz to 5k and watch the two amplitudes to see if they match or not over that range.
They don't necessarily. One can make them match by adjusting the tone controls.
I got real techy and inverted one of the signals and added it to the other. Theoretically one should see a flat line as a result rather than an AC waveform if they are the same. It wasn't.
Some conclusions:
1. The capacitors in the tone control section are 20% devices therefore some adjustment is necessary to make the the response match. Quite a bit in fact - perhaps turning the knobs 30 degrees different from one another.
2. Individual transistors have a gain mismatch (not an issue with op-amps using negative feedback in more recent designs) so checking the the signal amplitudes at the same points can differ.
3. Perhaps the biggest contributor is the speaker. Even same model speakers can vary to a degree. In my case the Peavey BW with the old spider magnet seemed to have a deeper response than the new BW super structure magnet speaker. The vent hole in the spider magnet is 20% bigger than the one in the supper structure. Maybe this is the reason?
4. The human ear is very good at picking up subtleties.
Anyway, that's my experience and I trust the science. I think this is true for most amps regardless of make/model. |
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Marty Broussard
From:
Broussard, Louisiana, USA
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Posted 11 Jan 2022 2:30 pm
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Thank you, Jim. In my case I’m connecting 2 different amps to 2 different cabinets/speakers and one of them sounds better. Your post confirms for me that there must be some tolerance issues that is making the difference b
_________________
RETIRED
"Technique is really the elimination of the unnecessary..it is a constant effort to avoid any personal impediment or obstacle to achieve the smooth flow of energy and intent" Yehudi Menuhin |
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