Why does my JCM 900 4500 HGDR HUM

bassistbobby · 10-05-2009, 03:43 AM

I have a JCM 900 4500 HGDR that is quiet as a mouse until I turn on my (or any) overdrive/distortion pedal. Then it makes a 60 cycle hum sound that is quite distracting. No other effects make it hum just overdrive and/or distortion pedals. I love the way those devices make my amp sound save for the hum. It has the same result no matter if the device is in my loop or before the amp. It also doesn't matter if other pedals are included or what power source I use. I need an explanation and or solution. Thanks

Jesstaa · 10-05-2009, 04:20 AM

Well it's not your amps fault. It's the pedals, some pedals do that.

bassistbobby · 10-05-2009, 06:35 AM

Thank you for your responce I very much appriciate any feedback I can get on this problem. I was hoping to get some help with this. If it is just the devices I'm using then what Overdrive pedals don't hum when used with Marshall amps? I looked at the YouTube Pro Guitar Shop demo of these pedals I've tried with my Marshall and none of them start to hum when the pedal is switched on in the demos. Right now I'm using a MI Audio Tube Zone pedal but have also used the Line 6 Uber Metal and the Boss Metal Zone and got the same hum. Isn't there at least a way to eliminate or reduce the hum? It's a little hard for me to just accept that MI Audio is selling a device that hums to a irratating level when used with tube amps. Does anyone know how to contact MI Audio? Thank you. Robert

PaoloJM · 10-05-2009, 06:41 AM

Quote:

Originally Posted by bassistbobby

Thank you for your responce I very much appriciate any feedback I can get on this problem. I was hoping to get some help with this. If it is just the devices I'm using then what Overdrive pedals don't hum when used with Marshall amps? I looked at the YouTube Pro Guitar Shop demo of these pedals I've tried with my Marshall and none of them start to hum when the pedal is switched on in the demos. Right now I'm using a MI Audio Tube Zone pedal but have also used the Line 6 Uber Metal and the Boss Metal Zone and got the same hum. Isn't there at least a way to eliminate or reduce the hum? It's a little hard for me to just accept that MI Audio is selling a device that hums to a irratating level when used with tube amps. Does anyone know how to contact MI Audio? Thank you. Robert

Are you using a battery or wall wart?

Jesstaa · 10-05-2009, 06:41 AM

A noise gate can help, I think the IC decimator or whatever is the best, but idk, I never use pedals, don't need them.

bassistbobby · 10-05-2009, 06:51 AM

Don't gates and filters lose some of the signal? I was hoping to eliminate the problem at it's source. I use a power supply and have tried several to see if that's causing it and they all sound the same. Would a battery instead help?

PaoloJM · 10-05-2009, 07:22 AM

Quote:

Originally Posted by bassistbobby

Don't gates and filters lose some of the signal? I was hoping to eliminate the problem at it's source. I use a power supply and have tried several to see if that's causing it and they all sound the same. Would a battery instead help?

Trying a battery would eliminate the power supply as a noise suspect, or not.

LesPaulopolis · 10-05-2009, 01:22 PM

Does it still hum when you're muting all the strings?

Frankie · 10-05-2009, 01:45 PM

Is the pedal on 10? If so, you're probably beat. I'm pretty sure all overdrive pedals hum when cranked.

bassistbobby · 10-06-2009, 04:59 AM

Sorry about the slow update I had too sleep and work. I tried replacing the dead battery and it didn't help. I tried using only battery power (new Duracell) and not a transformer, no improvement. I do not have it on 10. In fact I usually only have it on around 4. I e-mail MI Audio and they have been great so far. Fast response and they have asked me for photos of my pedals circuit board. I just sent those and will update as soon as something happens. If interested, check back in 24 hours for an update. Big THANK YOU to everybody.

TPR · 10-06-2009, 08:04 AM

Good to hear MI is on the job. By the way, it sounds like you've at least narrowed it down to the pedal itself, but have you tried that pedal with another amp to see if you still get the hum?

bassistbobby · 10-07-2009, 12:39 AM

OK here is what MI Audio said after seeing my circuit board.

what you can do is the following:

1) there is a wire coming from the 9V jack to the PCB right between the tone pot and the volume pot. The wire is labelled “+9V” on the PCB. Desolder that wire from the PCB.

2) Next, solder one end of a 100Ohm/1Watt resistor into the PCB where the wire went.

3) Solder the other end of that resistor (the floating end) to the 9V wire from the jack.

In other words, you’re soldering a 100Ohm resistor in series with the power supply like which will improve filtering.

Then he went on to say...

Please note though, that this only applies to some of the V3 Tube Zones. Most Tube Zones already have this fix in there.

I (bassistbobby) will post my results here once I've tried this fix. I am very encouraged by this suggestion from the manufacturer of my pedal. I'm also going to try the pedal with my Fender Ultimate Chorus following TPR's advice. The only trouble with that though is it could be only something that happens with tube amps and I only have the JCM 900 4500 HGDR.

bassistbobby · 10-09-2009, 07:55 PM

Well well well my friends what a difference. THIS really worked. How cool is that. I asked if they have any more cool mods that will improve my pedal? I'll let you know if I get any more from MI Audio. THANK YOU! Robert in Renton, Washington (state).

10-05-2009, 03:43 AM	#1 (permalink)
bassistbobby Junior Member Join Date: Sep 2008 Posts: 9	Why does my JCM 900 4500 HGDR HUM I have a JCM 900 4500 HGDR that is quiet as a mouse until I turn on my (or any) overdrive/distortion pedal. Then it makes a 60 cycle hum sound that is quite distracting. No other effects make it hum just overdrive and/or distortion pedals. I love the way those devices make my amp sound save for the hum. It has the same result no matter if the device is in my loop or before the amp. It also doesn't matter if other pedals are included or what power source I use. I need an explanation and or solution. Thanks

10-05-2009, 04:20 AM	#2 (permalink)
Jesstaa Senior Member Join Date: Apr 2009 Location: Gippsland, Vic, Australia. Posts: 1,063	Re: Why does my JCM 900 4500 HGDR HUM Well it's not your amps fault. It's the pedals, some pedals do that. __________________ GEAR LIST Marshall JCM900 4100 (6L6) (1995) Marshall Valvestate 1965A cab (????) Cort VX-2V (2008) H&S 7 String (Years are over rated) TUBES/SPEAKERS Power: Groove Tube 6L6GCB Phase Inverter: Chinese 12AX7A Pre: V1 - N.O.S Mullard ECC83. V2 Chinese 12AX7A Speakers: Celestion G10L-35 Marshall forever My tube amp & Real Music appreciation forum

10-05-2009, 06:35 AM	#3 (permalink)
bassistbobby Junior Member Join Date: Sep 2008 Posts: 9	Re: Why does my JCM 900 4500 HGDR HUM Thank you for your responce I very much appriciate any feedback I can get on this problem. I was hoping to get some help with this. If it is just the devices I'm using then what Overdrive pedals don't hum when used with Marshall amps? I looked at the YouTube Pro Guitar Shop demo of these pedals I've tried with my Marshall and none of them start to hum when the pedal is switched on in the demos. Right now I'm using a MI Audio Tube Zone pedal but have also used the Line 6 Uber Metal and the Boss Metal Zone and got the same hum. Isn't there at least a way to eliminate or reduce the hum? It's a little hard for me to just accept that MI Audio is selling a device that hums to a irratating level when used with tube amps. Does anyone know how to contact MI Audio? Thank you. Robert

10-05-2009, 06:41 AM	#5 (permalink)
Jesstaa Senior Member Join Date: Apr 2009 Location: Gippsland, Vic, Australia. Posts: 1,063	Re: Why does my JCM 900 4500 HGDR HUM A noise gate can help, I think the IC decimator or whatever is the best, but idk, I never use pedals, don't need them. __________________ GEAR LIST Marshall JCM900 4100 (6L6) (1995) Marshall Valvestate 1965A cab (????) Cort VX-2V (2008) H&S 7 String (Years are over rated) TUBES/SPEAKERS Power: Groove Tube 6L6GCB Phase Inverter: Chinese 12AX7A Pre: V1 - N.O.S Mullard ECC83. V2 Chinese 12AX7A Speakers: Celestion G10L-35 Marshall forever My tube amp & Real Music appreciation forum

10-05-2009, 06:51 AM	#6 (permalink)
bassistbobby Junior Member Join Date: Sep 2008 Posts: 9	Re: Why does my JCM 900 4500 HGDR HUM Don't gates and filters lose some of the signal? I was hoping to eliminate the problem at it's source. I use a power supply and have tried several to see if that's causing it and they all sound the same. Would a battery instead help?

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10-05-2009, 01:22 PM	#8 (permalink)
LesPaulopolis Senior Member Join Date: Jan 2009 Location: Minneapolis Posts: 426	Re: Why does my JCM 900 4500 HGDR HUM Does it still hum when you're muting all the strings? __________________ '68 RI LP Custom '93 Anniversary 6100 (6L6s) '90 JCM900 4100 (EL-34s) In Loop: TU-2 > CH-5 > DD-5 > Boss RC-20XL

10-05-2009, 01:45 PM	#9 (permalink)
Frankie Senior Member Join Date: Sep 2007 Location: Clearwater, FL Posts: 365	Re: Why does my JCM 900 4500 HGDR HUM Is the pedal on 10? If so, you're probably beat. I'm pretty sure all overdrive pedals hum when cranked. __________________ w w w . c o w b o y m a f i a . n e t Myspace.com \| YouTube \| Facebook

10-06-2009, 04:59 AM	#10 (permalink)
bassistbobby Junior Member Join Date: Sep 2008 Posts: 9	Re: Why does my JCM 900 4500 HGDR HUM Sorry about the slow update I had too sleep and work. I tried replacing the dead battery and it didn't help. I tried using only battery power (new Duracell) and not a transformer, no improvement. I do not have it on 10. In fact I usually only have it on around 4. I e-mail MI Audio and they have been great so far. Fast response and they have asked me for photos of my pedals circuit board. I just sent those and will update as soon as something happens. If interested, check back in 24 hours for an update. Big THANK YOU to everybody.

10-06-2009, 08:04 AM	#11 (permalink)
TPR Senior Member Join Date: Sep 2009 Posts: 161	Re: Why does my JCM 900 4500 HGDR HUM Good to hear MI is on the job. By the way, it sounds like you've at least narrowed it down to the pedal itself, but have you tried that pedal with another amp to see if you still get the hum? __________________ '91 JCM 900 Head w/ EL34s '68 Bassman Head- Blackfaced Hand Built 2x12 Classic 30 Gibson LP Studio w/ PAFs Epi LP Standard w/ G 57s The usual assortment of pedals and stuff

10-07-2009, 12:39 AM	#12 (permalink)
bassistbobby Junior Member Join Date: Sep 2008 Posts: 9	Re: Why does my JCM 900 4500 HGDR HUM OK here is what MI Audio said after seeing my circuit board. what you can do is the following: 1) there is a wire coming from the 9V jack to the PCB right between the tone pot and the volume pot. The wire is labelled “+9V” on the PCB. Desolder that wire from the PCB. 2) Next, solder one end of a 100Ohm/1Watt resistor into the PCB where the wire went. 3) Solder the other end of that resistor (the floating end) to the 9V wire from the jack. In other words, you’re soldering a 100Ohm resistor in series with the power supply like which will improve filtering. Then he went on to say... Please note though, that this only applies to some of the V3 Tube Zones. Most Tube Zones already have this fix in there. I (bassistbobby) will post my results here once I've tried this fix. I am very encouraged by this suggestion from the manufacturer of my pedal. I'm also going to try the pedal with my Fender Ultimate Chorus following TPR's advice. The only trouble with that though is it could be only something that happens with tube amps and I only have the JCM 900 4500 HGDR.

10-09-2009, 07:55 PM	#13 (permalink)
bassistbobby Junior Member Join Date: Sep 2008 Posts: 9	Re: Why does my JCM 900 4500 HGDR HUM Well well well my friends what a difference. THIS really worked. How cool is that. I asked if they have any more cool mods that will improve my pedal? I'll let you know if I get any more from MI Audio. THANK YOU! Robert in Renton, Washington (state).

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