Tweed Pro Volume Pot & Cap Question

[CaseyJones]

A couple notes:

The Weber pots are "good enough". Just about any pot that takes a direct hit to the knob is going to crackle.

I'd make sure I didn't have a bad coupling cap and DC on the grids. The coupling caps are there to block DC. If you have a really crummy Asian cap (there are good ones and there are bad ones) DC on the pot is going to sound like a bad pot. If the pot isn't super tight to the chassis (bad ground) it will do the same thing. I attach all my pots to a ground buss then I ground that to the preamp star ground.

Your bright cap across that pot is indicated on the Weber layout at 100p. That's on the low side, I use 250p but 330 or 470 are worth a try.

If you order from Apex Junior be sure to ask Steve about his vintage CTS 1 meg audios with push/pull switch on the back. Solder your bright cap across the switch, that way you have two "normal" channels until you pull the knob out. Or use the CTS pots on both channels, use the 100p cap on one channel and a 250p or 330p cap on the other channel. You then have two different bright channels available.

The best was to use the bright channel is with the channels jumpered. Crank up your normal channel to get the body of your tone, then crank up the bright channel to add edge. It's like having an extra set of tone controls before your tone controls. That facilitates a couple other tricks but we'll keep it simple for now.

IMHO that amp is semi-useless without both channels being functional.

[Jammin'John]

I'd make sure I didn't have a bad coupling cap and DC on the grids. The coupling caps are there to block DC. If you have a really crummy Asian cap (there are good ones and there are bad ones) DC on the pot is going to sound like a bad pot.

It's a good cap.

If the pot isn't super tight to the chassis (bad ground) it will do the same thing. I attach all my pots to a ground buss then I ground that to the preamp star ground.

That,I'll have to check.

Your bright cap across that pot is indicated on the Weber layout at 100p. That's on the low side, I use 250p but 330 or 470 are worth a try.

Won't that make the channel brighter ?

If you order from Apex Junior be sure to ask Steve about his vintage CTS 1 meg audios with push/pull switch on the back. Solder your bright cap across the switch, that way you have two "normal" channels until you pull the knob out. Or use the CTS pots on both channels, use the 100p cap on one channel and a 250p or 330p cap on the other channel. You then have two different bright channels available.

Is apex a good place to buy ?

The best was to use the bright channel is with the channels jumpered. Crank up your normal channel to get the body of your tone, then crank up the bright channel to add edge. It's like having an extra set of tone controls before your tone controls. That facilitates a couple other tricks but we'll keep it semi-simple for now.

IMHO that amp is semi-useless without both channels being functional.

True.

JJ

[CaseyJones]

Your bright cap across that pot is indicated on the Weber layout at 100p. That's on the low side, I use 250p but 330 or 470 are worth a try.

Won't that make the channel brighter ?

As far as I'm concerned the 100p makes for a bunch of "tweezed" sounding top end and not much else.

The way I set it up I'd never use the bright channel straight and I'd never use the normal channel straight. The normal channel doesn't have a lot of edge to it and the bright channel doesn't have much bottom end. Jumpered and blended you get both. If you want more big bad bottom you can crank the normal way up. If you want really crisp edge to cut through grab the bright channel. The only difficulty is the more you crank the bright volume the less effect the bright cap has.

That's the old 5F6/JTM45 jumpered channels trick that musicians have been using for, oh, 50 years now. Some of 'em.

If you order from Apex Junior be sure to ask Steve about his vintage CTS 1 meg audios with push/pull switch on the back. Solder your bright cap across the switch, that way you have two "normal" channels until you pull the knob out. Or use the CTS pots on both channels, use the 100p cap on one channel and a 250p or 330p cap on the other channel. You then have two different bright channels available.

Is apex a good place to buy ?

It depends. If you want everything in one stop, no, Apex Junior doesn't sell everything. On the other hand Steve surfs the surplus market and brings us some killer parts at cheap prices. Those Bourns pots? Good stuff! No one else has them. The CTS pots don't show up on his site but he has them, more killer parts there. He has teflon wire, capacitor deals, he has genuine Drake pilot lights every so often.

My take on the market for boutique amp parts... when you see something good buy all of it you can afford. So, if Steve has a good deal on capacitors... stock up! Teflon wire? That's where you get it. Bourns pots? Figure out what you'll need... for instance you can't have too many 1 meg audios... so I'd buy at least 10 of 'em. That way I don't have to walk around wif my thumb up my ass waitin' fer parts next time I need 'em!

[billyz]

I have found the PEC pots at Fry's for 6.95 in a blister pack, They are not labeld PEC, but look at the pot and you can see if it is. I am not fond of anything made in china. I would go for the vintage CTS pots. Again , one of the reasons I prefer the PEC is the taper seems more vintage feeling.

also, as for the brightness, you might want to consider a better sounding power tube. The Shuguang is known to be very bright and edgy sounding.

And to smooth out the highs a little more use a Polystyrene cap instead of ceramic or even silver mica. The originals used a mica cap, but the older dominoes sound a bit better than the newer ones.

[Jammin'John]

have found the PEC pots at Fry's for 6.95 in a blister pack, They are not labeld PEC, but look at the pot and you can see if it is.
Couldn't find it at their site.
http://www.frys.com/

I am not fond of anything made in china. I would go for the vintage CTS pots. Again , one of the reasons I prefer the PEC is the taper seems more vintage feeling.

I bought some chinese Bourns(hope they're good) & those CTS switchable pots.
http://www.apexjr.com/Bourns.htm
also, as for the brightness, you might want to consider a better sounding power tube. The Shuguang is known to be very bright and edgy sounding.

I gotta say that I've NEVER heard them described as bright & edgy.

In my normal channel I have to dime the treble and wish for more.

http://vintagemodern.informe.com/all-ab ... t1627.html

"Shuguang KT66 - The Shuguang is functional art. A great job has been done in nailing the look of the original KT66. This is a huge tube when compared to others used in guitar amps. You are advised to have a careful look at space availability before installing these guys. The specs on this tube are very similar to the 25-watt originals. They draw more heater current than a standard 6L6: 1400 ma. instead of the usual 900. You should be sure that your amp's power transformer has the capacity to handle the extra current draw. Bias these tubes hot for best results. While most tubes we tested were biased at around 60% of their rated plate dissipation, the Shuguangs sound very bright and crystalline in this range. Some may find it too bright. At 75% of rated dissipation, these tubes really provide that feeling of rolling thunder. If you want Country clean, bias them for 60-70%. If you need earlier breakup and a beefier sound then turn up the heat, but keep an eye on your power tranny. "
And to smooth out the highs a little more use a Polystyrene cap instead of ceramic or even silver mica. The originals used a mica cap, but the older dominoes sound a bit better than the newer ones."

I have 'em biased hot & they sound big,full,& warm.

JJ

[Jammin'John]

CaseyJones

"Your bright cap across that pot is indicated on the Weber layout at 100p. That's on the low side, I use 250p but 330 or 470 are worth a try."

So a larger cap will dump some treble ?

JJ

[Jammin'John]

A couple notes:

The Weber pots are "good enough". Just about any pot that takes a direct hit to the knob is going to crackle.

I'd make sure I didn't have a bad coupling cap and DC on the grids. The coupling caps are there to block DC. If you have a really crummy Asian cap (there are good ones and there are bad ones) DC on the pot is going to sound like a bad pot. If the pot isn't super tight to the chassis (bad ground) it will do the same thing. I attach all my pots to a ground buss then I ground that to the preamp star ground.

Your bright cap across that pot is indicated on the Weber layout at 100p. That's on the low side, I use 250p but 330 or 470 are worth a try.

If you order from Apex Junior be sure to ask Steve about his vintage CTS 1 meg audios with push/pull switch on the back. Solder your bright cap across the switch, that way you have two "normal" channels until you pull the knob out. Or use the CTS pots on both channels, use the 100p cap on one channel and a 250p or 330p cap on the other channel. You then have two different bright channels available.

The best was to use the bright channel is with the channels jumpered. Crank up your normal channel to get the body of your tone, then crank up the bright channel to add edge. It's like having an extra set of tone controls before your tone controls. That facilitates a couple other tricks but we'll keep it simple for now.

IMHO that amp is semi-useless without both channels being functional.

Man,I tried 250 & 450 and it was too bright



1

JJ

[billyz]

If 100 pf is too bright then you want to go to 47pf. A larger value passes more frequencies going lower in the spectrum. Also, Did you mention the speaker you are using? The best sound would be an Alnico , and broken in . A new one could be too bright. Actually it all makes a difference. Speakers Tubes, Caps, Guitar , pickups, cabinet, baffle,. I find Metal film resistors and polyprop Orange drops to be bright and even strident.

[Jammin'John]

I wanted to put the pull pot that apex sent me but it is linear taper.
The smallest cap I have is 100p.
It works pretty good now if I bridge the channels and use mostly normal with a little bright channel for some sizzle.
I suppose I could series wire 2x100p's to get 50p.
It's wierd how series & parallel works different for caps.

I don't like alnico's in tweed amps.
They already compress a lot.I like the punch of ceramics.
I am runnin' a custom Weber 15" with a celestion motor and a jensen cone and a 5 pound magnet !
I play tele's.
JJ