Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: labb on September 29, 2011, 08:41:19 am
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Do different types and or brand of caps used as coupling caps have any effect on noise in an amp? ie: Mallory 150's vrs. Orange drop.
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some will say no,I say yes. There is a real difference between types like 715p orange drops and say mallory 150's.
Then there are paper in oils,metal polyester etc.etc.
I would not venture to say that any one brand is better than another but they are definitely different.
Some amps like one brand more than others but that is pretty subjective too.
I do like the difference in tone when you get those awful sounding(to my ears) mylar caps out of a blues jr. and use orange drops.
There are quality differences between capacitors for sure,but it blurs a bit when you start entering the 'audiophile' territory.
They make some pretty lofty claims when you get coupling caps that cost in the neighborhood of 35.00 and up for EACH one.
I have built a couple of 5E3's using Auricaps at about 6.00 a pop and they do sound pretty damn nice,but better than others?Maybe,maybe not.
Not many people want to spring for a set of "premium" coupling caps so we likely won't find out any time soon.
Maybe on my next 36 watt build I'll pop a set of the real expensive ones in and see what it sounds like.I'm not holding my breath with anticipation.
Go to 'Allessandro high end products' and have a look at his caps. :huh:
Some look like old military NOS to me rather than new production.I don't think I'm going to part with 50.00 each to find out if they are better!!
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I like Orange Drops: not just for the stability and sound, but because they really make a hand-made board look NICE! :think1:
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Mallory's look better. :l2:
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Do different types and or brand of caps used as coupling caps have any effect on noise in an amp? ie: Mallory 150's vrs. Orange drop.
Some caps may be slightly microphonic, some can pick hum (reversing them usually cures the problem). But there's strictly no subjective difference between properly used caps of similar construction.
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Mallory's look better.
Not the white ones. :icon_biggrin:
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Thanks for the replys. I ask because I just finished a 5B3 build that has a higher noise level when cranked than I care for. It is the second that I have built and the first one is quieter than this one. The components (caps, resistors, pots, transformers and Power tubes) are the same. The layout is the same. Only difference is that I used 6SL7's(new production) for V1 and V2 instead of the 6SC7's(NOS) as in the original. I am going to start tinkering with it to see if I can lower the noise level and my feeble mind got to thinking about changing the coupling caps from Mallory 150's to Orange Drops just to see if I could tell any difference. I will change the anode resistors from 1/2 watt carbon compt's to 1 watt carbon film. That should help some. Any suggestions would be appreciated.
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Mallory's look better. :l2:
:worthy1: The yellow ones. The ones we cant get anymore
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I will change the anode resistors from 1/2 watt carbon compt's to 1 watt carbon film.
Or even 2 watt. Or metal film. Big Rs are less noisy.
BTW 6SL7s - or all dual triodes in octal guise - don't use balanced heaters and can be somewhat picky when it comes to the 6V3 supply and the overall lead dress: you can pick hum very easily.
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Thanks FYL. Not much hum in this amp untill I max out the #2 input vol. pot. Mostly what I would call white noise after you get past 5. More so on the #2 channel. The layout follows Fenders with the exception that I did not run any of the wires under the board. Everything is on top and about 5/8 inch above the board components. Sig. and all are crossed at right angles. Heater wiring is in phase, tight twist with a drill and tucked under the lip of the chassis. I thought about using zip cord for the heater wiring running it over the tubes but stayed with what I know. I ran shielded cable to the grid of V2 from the vol. pot.
FYI, the Mallory 150 caps on the inputs to V1 were both microphonic with the pots maxed. I just changed them out to Sprague Polyester OD's (4PS S50). The OD's are not microphonic.
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Only difference is that I used 6SL7's(new production) for V1 and V2 instead of the 6SC7's(NOS) as in the original.
Did you try swapping tubes between the 2 amps, and seeing if the noise stayed with the tubes?
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HBP--Have not tried swapping tubes between the two amps. Would have to rewire to do it. The pin-outs are different..I have swapped around three different 6SL7's and can not tell much difference..I think you are probably correct in pointing to the tubes..If I can find a set of the 6SC7's for a good price I am going to buy them and give it a try...I do not have the other amp at this time. A player has it and my spare 6SC7's and he is out of town for a while.
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FYI, the Mallory 150 caps on the inputs to V1 were both microphonic with the pots maxed. I just changed them out to Sprague Polyester OD's (4PS S50). The OD's are not microphonic.
Different construction. The 150s are fitted with epoxy endcaps and a printed plastic wrapper around the body. The PS series are fully dipped in epoxy - more rigid construction.