820R on V1 pin 2 reduce hum?
Moderators: pompeiisneaks, Colossal
820R on V1 pin 2 reduce hum?
Will an 820R resistor on V1 pin 2 reduce the amount of 50 or 60 cycle hum I am experiencing with my new TW Express build? I've read several posts where people liked the tonal qualities better (such as the "Ingrid Mod" thread) but was curious if it would help there, as I tried it out tonight and am experiencing a "fair" amount of hum coming from the amp when it's at about 4 on the volume control. Tone was good but I was thinking about adding it anyway to "smooth and round it". I also noticed this Express is VERY unforgiving with guitars that are not grounded as well as others I have. So, would that help or is it unrelated? Sorry I'm too new at this to know. Any comments are appreciated.
https://www.facebook.com/trialbyfirerocks
Be sure your tinfoil hat has a good low impedance ground.
Be sure your tinfoil hat has a good low impedance ground.
Re: 820R on V1 pin 2 reduce hum?
A small value resistor there will help keep the amp stable.
I use one there. I think Ken recommended this to Glen K for his original.
That may have been on a Liverpool, but they share the same pre-amp design.
820 to 2k2 here is the norm.
It may help with hum - V1 is very touchy in an Express.
Very, very touchy.
Good Luck.
Bob
I use one there. I think Ken recommended this to Glen K for his original.
That may have been on a Liverpool, but they share the same pre-amp design.
820 to 2k2 here is the norm.
It may help with hum - V1 is very touchy in an Express.
Very, very touchy.
Good Luck.
Bob
Why Aye Man
Re: 820R on V1 pin 2 reduce hum?
Thanks Bob....yes this amp gives touchy a whole new meaning on V1 I really love the tone I can get with a (very) long plate 1950's GE but that position is so receptive to microphonics that I went to a Russian short plate for last night's jam session just to try to cut that down. I noticed the "Unnamed" (real) wreck has what looks like a 1.2 K on it in the same spot, so thought maybe it would help in both issues -- thanks again. I'll try it tonight.
https://www.facebook.com/trialbyfirerocks
Be sure your tinfoil hat has a good low impedance ground.
Be sure your tinfoil hat has a good low impedance ground.
Re: 820R on V1 pin 2 reduce hum?
Other initial thoughts about the hum issue were: put in a socket at V1 with a shield over it (saw that in some real wrecks also) or go to chopsticking the heater leads. But I was pretty careful with lead dress putting it together and sure is easier to try the resistor than swap out a socket 
https://www.facebook.com/trialbyfirerocks
Be sure your tinfoil hat has a good low impedance ground.
Be sure your tinfoil hat has a good low impedance ground.
Re: 820R on V1 pin 2 reduce hum?
Are you sure the hum is coming for the first stage, I assume you've pulled the first tube out and the amp goes dead quiet?
Are you going to do the whole mod where you use shielded cable from the volume control with the shield attached to the plate?
Are you going to do the whole mod where you use shielded cable from the volume control with the shield attached to the plate?
Yours Sincerely
Mark Abbott
Mark Abbott
-
martin manning
- Posts: 14308
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: 820R on V1 pin 2 reduce hum?
The input grid resistor (unless it's very large) and tube shield are only going to affect ultrasonic frequencies. I guess that's hum to some creatures, but not the place for you to look. What frequency is the hum? If you can match it with a guitar, then it's 120Hz ripple-related. If you need a bass, then it's 60Hz, more likely from filament wiring or a grounding issue with the PT primary.
Re: 820R on V1 pin 2 reduce hum?
Thank you gentlemen...that gives me more to investigate....and some ways to do it. What sparked the question was that last night I tried my strat through the thing and its got a set of Lindy Fralin's in it. WOW was it noisy, but not as noisy as the next guitar I tried, which was my Telecaster with humbuckers in split-coil mode. It might even just be ALL the guitar's fault. But its fairly easy to do what Mark said and pull v1 to see "if" it is or is not coming from there. I'm going to try a power conditioner too to see if it makes any difference. Mind you it isn't so loud that I can't play on it....just seems to me like I should be able to get it "whisper" quiet as that will greatly help when I go to try and record with it. Thanks Mark and Martin!
https://www.facebook.com/trialbyfirerocks
Be sure your tinfoil hat has a good low impedance ground.
Be sure your tinfoil hat has a good low impedance ground.
Re: 820R on V1 pin 2 reduce hum?
Mark, I already used a good grade of shielded wire from the volume pot to that pin (got some from Hoffman before I started). And shield is attached only to one end.
https://www.facebook.com/trialbyfirerocks
Be sure your tinfoil hat has a good low impedance ground.
Be sure your tinfoil hat has a good low impedance ground.
-
martin manning
- Posts: 14308
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: 820R on V1 pin 2 reduce hum?
whisper-quiet Trainwreck = oxymoron
Re: 820R on V1 pin 2 reduce hum?
Heheh! OK Martin, I was wondering about that too.
https://www.facebook.com/trialbyfirerocks
Be sure your tinfoil hat has a good low impedance ground.
Be sure your tinfoil hat has a good low impedance ground.
-
geetarpicker
- Posts: 918
- Joined: Sat Mar 12, 2005 8:08 pm
- Location: Nashville, TN
- Contact:
Re: 820R on V1 pin 2 reduce hum?
Typically with a Trainwreck (and most amps in general) if you turn up the amp, and turn your guitar off, you are then specifically hearing just the noise of the amp. Then as you dial up your guitar you will hear how quiet, or not your pickups are.
Most any single coils will be noisy with any high gain amp, however with my Fralins in my strat I've also been using the Suhr hum cancelling back plate which works quite well. Still, not quite humbucker quiet but well worth the investment IMHO. Also simply orienting your guitar in one direction or another can help quite a bit to null out the hum, not really practical on stage perhaps but quite workable in the studio.
A related note on the Fralins. The Suhr cancelling back plate works as designed with 3 all standard wind pickups, not the reverse wind pickup the Fralins use in the middle position. Typically with the Suhr plate you replace your middle pickup (if it's a reverse wind) with a standard wind. That said I found the natural hum canceling properties of the reverse middle plus bridge or neck pickup (positions 2 and 4) are still better than what the Suhr plate can do. So on my strat I left the standard wind middle pickup, and came up with a wiring scheme where my Suhr back plate only kicks in for the bridge or neck alone positions 1 and 5, but is bypassed on positions 2 and 4 which are naturally hum canceling with the middle reverse would pickup. Then I have the best of both worlds... with one exception, being my middle pickup alone is noisy as a normal single coil, but that is my least used pickup selection anyway on a strat, so I compromise that to get the lowest noise possible on the other 4 positions. In the end my most quiet positions are 2 and 4, but my bridge pickup or neck pickup alone 1 and 5 are quite improved by the Suhr plate, then my middle pickup is just noisy. I just plan on a little body English and positioning if I use the middle pickup at high gain and/or not worry about it.
Also any light dimmers in the house will cause noise, same for fluorescents, and typically it is air born radiated noise an AC line suppressors won't do much to fight it. IF you must have a light dimmer full up is typically lower emitted noise than dimmed which tends to be much worse. So dimmer wise either go full up or off. That said, I've seen some dimmers where they have a full bypass for full up and those are great if you must have dimmers. Then you can bypass them full up to jam....
Most any single coils will be noisy with any high gain amp, however with my Fralins in my strat I've also been using the Suhr hum cancelling back plate which works quite well. Still, not quite humbucker quiet but well worth the investment IMHO. Also simply orienting your guitar in one direction or another can help quite a bit to null out the hum, not really practical on stage perhaps but quite workable in the studio.
A related note on the Fralins. The Suhr cancelling back plate works as designed with 3 all standard wind pickups, not the reverse wind pickup the Fralins use in the middle position. Typically with the Suhr plate you replace your middle pickup (if it's a reverse wind) with a standard wind. That said I found the natural hum canceling properties of the reverse middle plus bridge or neck pickup (positions 2 and 4) are still better than what the Suhr plate can do. So on my strat I left the standard wind middle pickup, and came up with a wiring scheme where my Suhr back plate only kicks in for the bridge or neck alone positions 1 and 5, but is bypassed on positions 2 and 4 which are naturally hum canceling with the middle reverse would pickup. Then I have the best of both worlds... with one exception, being my middle pickup alone is noisy as a normal single coil, but that is my least used pickup selection anyway on a strat, so I compromise that to get the lowest noise possible on the other 4 positions. In the end my most quiet positions are 2 and 4, but my bridge pickup or neck pickup alone 1 and 5 are quite improved by the Suhr plate, then my middle pickup is just noisy. I just plan on a little body English and positioning if I use the middle pickup at high gain and/or not worry about it.
Also any light dimmers in the house will cause noise, same for fluorescents, and typically it is air born radiated noise an AC line suppressors won't do much to fight it. IF you must have a light dimmer full up is typically lower emitted noise than dimmed which tends to be much worse. So dimmer wise either go full up or off. That said, I've seen some dimmers where they have a full bypass for full up and those are great if you must have dimmers. Then you can bypass them full up to jam....
Last edited by geetarpicker on Sun Feb 16, 2014 9:48 am, edited 5 times in total.
Re: 820R on V1 pin 2 reduce hum?
I also recommend that you know your power source, how many volts are coming out of the wall and is it clean. I get earth noises and my place is relatively new.
Yours Sincerely
Mark Abbott
Mark Abbott
Re: 820R on V1 pin 2 reduce hum?
Thanks Glen and Mark.
Glen, I think that's probably exactly what I need to do, I have read about those plates under single coils. Last night (at the amps first gig even) I turned it all the way up and with no line from my guitar plugged in it was REAL quiet even in a pretty noisy club. I think I just need to shore up the guitars. For last night I used a tone-sucking isolation transformer box and my noise gate - and I always run a conditioner / test with a test plug 'cause clubs have notorious wiring problems. And I use decent cables...not a big fan of monster cable but they are pretty durable so far and I got them cheap. What, me worry?
Mark, I am at 121 volts here and though the house is old it's quite steady between 120 and 122. One of my power conditioners has the bonus of a digital readout. I went ahead and put in the resistor to try it.
Yes I have florescent in the home practice room....and I know they contribute. But what REALLY gives me grief is the dimmer packs the lights use at the gigs! When dimmed as you know, they are nothing but a great big noise making load. Unfortunately we don't own them.
Glen, I think that's probably exactly what I need to do, I have read about those plates under single coils. Last night (at the amps first gig even) I turned it all the way up and with no line from my guitar plugged in it was REAL quiet even in a pretty noisy club. I think I just need to shore up the guitars. For last night I used a tone-sucking isolation transformer box and my noise gate - and I always run a conditioner / test with a test plug 'cause clubs have notorious wiring problems. And I use decent cables...not a big fan of monster cable but they are pretty durable so far and I got them cheap. What, me worry?
Mark, I am at 121 volts here and though the house is old it's quite steady between 120 and 122. One of my power conditioners has the bonus of a digital readout. I went ahead and put in the resistor to try it.
Yes I have florescent in the home practice room....and I know they contribute. But what REALLY gives me grief is the dimmer packs the lights use at the gigs! When dimmed as you know, they are nothing but a great big noise making load. Unfortunately we don't own them.
https://www.facebook.com/trialbyfirerocks
Be sure your tinfoil hat has a good low impedance ground.
Be sure your tinfoil hat has a good low impedance ground.
Re: 820R on V1 pin 2 reduce hum?
It may be "cheating", but I bought a bunch of NOS Mil-Std 5751's, and swap them one by one into the V1 position on Wreck-style amps until I find the quietest one.
Re: 820R on V1 pin 2 reduce hum?
Ken Moon wrote:It may be "cheating", but I bought a bunch of NOS Mil-Std 5751's, and swap them one by one into the V1 position on Wreck-style amps until I find the quietest one.
Do the same thing with 12AX7,then once you find it, put that in V2. Now go back and try the ones for V1. It makes a difference to find a good tube for V2 first, for whatever tube you want to try for V1.
I have a bunch of those 5 star 5751 and JAN tubes. It seems no matter what tube of any kind, you can weed through them and find good and not so good. I had a amp the other day using 6SL7GT tubes. I found one brown base one that I wish all were like.