Build Your Own Clone Message Board

It is currently Thu Mar 28, 2024 11:42 pm

All times are UTC - 6 hours




Post new topic Reply to topic  [ 24 posts ] 
Author Message
 Post subject: Tweed Royal Hum
PostPosted: Sat Sep 14, 2013 5:40 pm 
Offline

Joined: Sat Sep 14, 2013 8:08 am
Posts: 13
Location: UK
Hi chaps,

I’ve built a Tweed Royal which sounds great apart from what l have determined as a very loud mains hum when the Cut Switch is turned off (fully ACW) with or without anything plugged in. SE and PP modes.

I am in the UK and on 240v and wired accordingly.

l have checked over my build too many times to recall and apart from an under the board wiring check, everything looks good.

l’ve looked through the forum and performed the wire probing and heater wire placement, screened input cables and amp back cover (combo 1x12”). All to no effect.

I never thought it was on the input side as when touching input wires it is a totally different pitch and recognisable as audio signal hum.

After researching l found that 240v 50 cycle mains hum as a note, is
'50 Hz is between G (49.04 Hz) and G♯ (51.93 Hz)

This is exactly what l’m experiencing, the note of ‘G’.

As soon as the Cut Switch is turned on(CW), the hum decreases and diminishes as it’s rotated clockwise.

As a newbie, any help would be greatly appreciated! Thank you.

Bob.


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Sep 14, 2013 5:56 pm 
Offline

Joined: Tue Jan 17, 2012 12:43 pm
Posts: 643
Location: Between sjaustin and duvoodooman
BobAcrossThePond wrote:
This is exactly what l’m experiencing, the note of ‘G’.


That's just the built in tuner on this full-featured tweed! :wink:

Seriously, a number of us have asked about the same thing. Mine does it too. I just tend to avoid clicking it off.

_________________
Twisting and tinning is for chumps.


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Sep 14, 2013 6:02 pm 
Offline
User avatar

Joined: Mon Jul 07, 2008 9:26 am
Posts: 1328
Location: UK
mine did it.... (im in the uk) but then i noticed that it went away significantly . it turns out the power supply adaptor i was using was not the best and i had a switched adaptor from another item sharing the power. I changed to a filtered 4 way gang (belkin) and the noise is much much lower.


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sun Sep 15, 2013 10:55 am 
Offline

Joined: Sat Sep 14, 2013 8:08 am
Posts: 13
Location: UK
Hey Guys.

Happened on this after spending another day on it. Has anybody used one of these?...

'Electro Harmonix Hum DeBugger'

Will it only eliminate hum at the input stage or could it resolve the Cut Switch hum?

Cheers.


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sun Sep 15, 2013 11:21 am 
Offline
User avatar

Joined: Mon Jul 07, 2008 9:26 am
Posts: 1328
Location: UK
I'm afraid that's input stage only, it won't solve the power hum.


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Mon Sep 16, 2013 10:09 am 
Offline
Moderator
User avatar

Joined: Wed Apr 26, 2006 5:14 pm
Posts: 8659
Location: Truckee, CA
My amp doesn't have an increased line noise hum when I switch off the cut control. Looking at the wiring diagram, I noticed that the 25µf cap that hangs off the cut control is grounded to the main filter cap area. Out of habit, when I built my amp, I grounded that cap to the pre amp side of things - it is grounded to pin 1 of the second volume control, the same spot where the .0047µf tone cap is grounded to the second volume control. It's purely an empirical observation, but maybe I stumbled onto something. Try it.

_________________
MasterDelayer/Reverbrador/Ampaholic/TopJacker


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Tue Sep 17, 2013 7:10 am 
Offline

Joined: Sat Sep 14, 2013 8:08 am
Posts: 13
Location: UK
BINGO!! YOU'RE THE BOY!! 90% Gone l'd say. THANK YOU.

Could it be a 240v 50 Hz cycle thing only experienced with this voltage? Sounded like the 633 Squadron somewhere up there in them thar hills. Anyway, it worked for me.

l'm not one for giving up, so this really was frustrating as l intend to mic this little gem up at smaller venues.

7 DAYS!

...and hey old chum, is there anything to eliminate a loud 'pop' when switching the tone 'on'... oh ye wizard?
l notice the 470pF cap from my tone pot is different in appearance to photo's. It's blue with WPK-X1, 500-Y1, n47 M on it. Is this an alternative equivalent or could it be this?

What a wonderful place this is and thanks to others for contributing. We all need a little help now and then.

Bob.


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Tue Sep 17, 2013 7:25 am 
Offline
Moderator
User avatar

Joined: Tue Jan 02, 2007 1:24 pm
Posts: 16196
Location: Albany, NY
Morgan wrote:
It's purely an empirical observation, but maybe I stumbled onto something....

Nice "stumble", Morgan! Image And in honor of it:


_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Wed Sep 18, 2013 9:53 am 
Offline
User avatar

Joined: Tue Feb 07, 2012 3:18 pm
Posts: 7321
Location: Nashville, TN
duhvoodooman wrote:
Nice "stumble", Morgan! Image And in honor of it:



Great call Bob (from back across the pond) !!!!!

_________________
powerpopguy wrote:
warm places theory sounds plausible. Occasionally, I wake up and think my snake is missing too, but it turns out it's just a chilly morning. :P


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Feb 13, 2016 12:26 pm 
Offline

Joined: Mon May 10, 2010 12:01 pm
Posts: 25
As I was performing this mod, because I can't leave well enough alone, I managed to pull a lead out of that 25uf capacitor. I stuck it back together and ordered a couple replacements online, but is it at all safe to play the amp while I'm waiting for the new cap to show up? Would it be safer to run with the cut knob turned on or just a bad idea in general?

Basically I want to outdo my downstairs neighbors who's practicing his bass right now.

Davin


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Feb 13, 2016 12:39 pm 
Offline
Moderator
User avatar

Joined: Wed Apr 26, 2006 5:14 pm
Posts: 8659
Location: Truckee, CA
Just remove the 25uf cap. The amp won't have as much gain with the cut control off, but it will be safe to use.

_________________
MasterDelayer/Reverbrador/Ampaholic/TopJacker


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Feb 13, 2016 12:43 pm 
Offline

Joined: Mon May 10, 2010 12:01 pm
Posts: 25
Sweet, thanks. New one will be here tuesday but in the meantime ...

Should I run a wire to ground in place of the capacitor?

Davin


Top
 Profile  
 
 Post subject: Tweed Royal Hum
PostPosted: Sat Feb 13, 2016 12:55 pm 
Offline
Moderator
User avatar

Joined: Wed Apr 26, 2006 5:14 pm
Posts: 8659
Location: Truckee, CA
No - do not run a ground wire there. There is already a resistor setting the bias for that part of the circuit.

_________________
MasterDelayer/Reverbrador/Ampaholic/TopJacker


Top
 Profile  
 
 Post subject: Tweed Royal Hum
PostPosted: Sat Feb 13, 2016 12:57 pm 
Offline
Moderator
User avatar

Joined: Wed Apr 26, 2006 5:14 pm
Posts: 8659
Location: Truckee, CA
Really though, it'll be the same as turning the cut control all the way down without clicking it off. You could jut remove the cap and make sure not to click off the cut control

_________________
MasterDelayer/Reverbrador/Ampaholic/TopJacker


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Feb 13, 2016 12:59 pm 
Offline

Joined: Mon May 10, 2010 12:01 pm
Posts: 25
Thanks, Morgan, for all the advice and tips I dug up on the forums. One last question: what would replacing the cap with a 22uf instead do for the amp. I have one or two of those kicking around rated at 25v.

Davin


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Feb 13, 2016 1:38 pm 
Offline
Moderator
User avatar

Joined: Wed Apr 26, 2006 5:14 pm
Posts: 8659
Location: Truckee, CA
A 22uf would make zero difference. Go ahead and install one.

_________________
MasterDelayer/Reverbrador/Ampaholic/TopJacker


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Feb 13, 2016 1:38 pm 
Offline
Moderator
User avatar

Joined: Wed Apr 26, 2006 5:14 pm
Posts: 8659
Location: Truckee, CA
And you're welcome! :)

_________________
MasterDelayer/Reverbrador/Ampaholic/TopJacker


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Fri Feb 19, 2016 6:17 pm 
Offline

Joined: Mon May 10, 2010 12:01 pm
Posts: 25
Another question. I did the cut capacitor grounding mod and it helped for sure. but what i did notice after firing it up again is that there's a lot more noise in the bright channel if i don't have a chord plugged in. there's the 60hz hum and a loud hiss from about 1.5 on up. is this just a wire dressing issue? i'm going out of town for a week so i won't be poking around in there for a bit, but when i get back i was going to see if i can't eliminate it or at least tame it a bit. it's a little overwhelming, particularly when i want to attenuate the signal with the bright volume control while plugged into the normal channel.

I also just realized they shipped me some shielded cable to use on that one long run from the cut pot to the speaker out pot. that may be on the list of things to do although i expect it'll be a bit of a pain so maybe i'll learn to love the hum.

Davin


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Fri Feb 19, 2016 6:22 pm 
Offline
Moderator
User avatar

Joined: Wed Apr 26, 2006 5:14 pm
Posts: 8659
Location: Truckee, CA
It is probably lead dress. Running shielded cable from the tubes to the center lug on each volume control also helps a lot in these amps. You only ground the shield at the vol pot end.

_________________
MasterDelayer/Reverbrador/Ampaholic/TopJacker


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Fri Feb 19, 2016 7:09 pm 
Offline

Joined: Mon May 10, 2010 12:01 pm
Posts: 25
Strangely, there was zero hum (literally none) when I first fired the amp up. Then the power transformer blew and when I put the new one in the hum showed up. In any case, I'm going to do some poking and prodding in a few weeks. Since I'm usually plugged into the bright channel anyway, and plugging a cable in seems to eliminate that problem almost completely, I'm just going to enjoy the racket for a bit before I go back in there and screw something else up.


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Dec 30, 2017 4:09 pm 
Offline

Joined: Tue Nov 21, 2017 1:53 pm
Posts: 10
Thanks Morgan!

Moving the cap for the cut control as you suggested made a HUGE difference in the noise on my TR too. Very quiet once it was moved. I was a bit disappointed with the amp beforehand.


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Dec 19, 2020 7:43 pm 
Offline

Joined: Tue Jan 17, 2012 12:43 pm
Posts: 643
Location: Between sjaustin and duvoodooman
Morgan wrote:
My amp doesn't have an increased line noise hum when I switch off the cut control. Looking at the wiring diagram, I noticed that the 25µf cap that hangs off the cut control is grounded to the main filter cap area. Out of habit, when I built my amp, I grounded that cap to the pre amp side of things - it is grounded to pin 1 of the second volume control, the same spot where the .0047µf tone cap is grounded to the second volume control. It's purely an empirical observation, but maybe I stumbled onto something. Try it.


Finally got around to this last night and bye golly it did the trick! Thanks Morgan!

_________________
Twisting and tinning is for chumps.


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Dec 19, 2020 8:53 pm 
Offline
Moderator
User avatar

Joined: Tue Jan 02, 2007 1:24 pm
Posts: 16196
Location: Albany, NY
oldlefty wrote:
Morgan wrote:
My amp doesn't have an increased line noise hum when I switch off the cut control. Looking at the wiring diagram, I noticed that the 25µf cap that hangs off the cut control is grounded to the main filter cap area. Out of habit, when I built my amp, I grounded that cap to the pre amp side of things - it is grounded to pin 1 of the second volume control, the same spot where the .0047µf tone cap is grounded to the second volume control. It's purely an empirical observation, but maybe I stumbled onto something. Try it.

Finally got around to this last night and bye golly it did the trick! Thanks Morgan!

Talk about serendipity! Been playing thru my TR quite a bit lately and had noticed a fair bit of audible hum, but I figured it was just the nature of the Tweed circuit. Then I come across Lefty's new post to this old thread this evening. So I fire up the amp and play around with the Cut control a bit, and WHADDAYA KNOW, that's where it's coming from! So I popped the hood, moved that cap ground over to the preamp side where Morgan said to put it, and BAM! 90% of the hum is gone! So thank you Lefty, and thank you Morgan! :mrgreen:

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2


Top
 Profile  
 
 Post subject: Re: Tweed Royal Hum
PostPosted: Sat Dec 19, 2020 9:15 pm 
Offline
Moderator
User avatar

Joined: Wed Apr 26, 2006 5:14 pm
Posts: 8659
Location: Truckee, CA
Merry Christmas boys - the thread that keeps on giving!

_________________
MasterDelayer/Reverbrador/Ampaholic/TopJacker


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 24 posts ] 

All times are UTC - 6 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group