static from mf101 w/twin reverb amp

[tboned]

I've always put up with a bit of interference/noise from my moogerfoogers, since it's never anything major. My Fender Twin Reverb RI amp will often make a bit of static/ fuzziness/negligible noise, on the level of normal mf noise or less. It picks up an occasional radio frequency, always at quiet and ignorable levels.
After listening to a recording of myself and hearing a muddier tone than the warm one I'm going for, I adjusted the amp and found a great tone, realizing I really prefer having the amp's "BRIGHT" switch activated, which I've never done in five years with this amp.
Then I plugged in the moogs: loud, unacceptable static. A gentle, albeit dominatingly loud hissing or whooshing. After narrowing the source to the mf101 and the bright switch, I'm stumped. The other mfs are all fine. Flip the bright switch off, and the sound is gone. What causes this? Is it possible to use the 101 and the bright setting without this noise?
Solutions? Ideas to try?
Thank you for any help or suggestions.

[asd]

http://www.moogmusic.com/forum/viewtopic.php?t=1314

check out quiet channel's post especially. its a start at least, there might be some older threads in the forum too.

[tboned]

Thanks for your response, asd. I neglected to mention that I suspect that this sound is not radio frequency noise. At any rate, it sounds completely unlike any radio interference I've gotten before. But please do educate me! I also forgot to mention that the noise happens when in bypass or not, it's just a bit louder when not. The drive knob seems to barely affect the noise's volume at all.

I've already searched these forums pretty exhaustively. I've been lurking around for years, but I was thinking this issue seems to be a bit different than the several existing 'mf101 noise issue' posts.

I'm fairly confident I can lay the blame on Fender, and I'll probably start digging into amp sites. However, my uneducated hypothesis is that this is some fluke combination of the 101 and "bright" mode that adds up to static. I'm curious as to what any of you might know about what a "bright" circuit does, exactly, and how it might be interacting with the 101's normal signal. Perhaps that particular electrical path allows some specific wavelength which matches some loud radio static? I don't know what I'm talking about. I figured I was more likely to find Physics/Electricity type wizards around here.

If the sound is radio frequencies, how can I tell/be sure? I hear no faint voices, variations, anything. Just pure, constant hiss (whoosh?). The brass sheets did sound like a cool project, but if it won't solve the problem, it'll have to wait. I'll go do some reading up on shielding... thanks again in advance for any insight or directions to knowledge.

[Dr.T]

Hello there tboned,

the bright switch in a Twin Reverb is based on the most unspectacular circuit: it is nothing more than a small capacitor (120 pF, if I remember correctly) switchable to bridge the "input" and "ouput" connection of the volume control. This lets the high frequencies travel past the control with much less attenuation than the lower frequencies - but the effect is VERY MUCH dependent on how the volume control is set. If the volume is turned up to "10", there wil be no effect, but if your setting is at low volume (which, if your are a reasonable person, will most probably be the case with a Twin ), then the effect can be quite dramatic and will - relatively - emphasise any high frequency noise or ringing from the MF101 quite severly.

Since I have, with the many Fender amps I have owned, customised or rebuilt, never encountered anything pointing to the problem you have, I suspect that the source of te issue may eb the MF101, after all. I have only acquired an MF101 mysefl recently, but have been confronted with the odd noise and ringing coming from the MF101 or caused by it. This is not to take anything away from the MF101 - it is a brillantly sounding and very usable cool device.

Does the noise you get change with the control setting of the MF101? Maybe this could give a clue.

Kind regards and good luck from sunny Southern Bavaria,

T.

[dotlikeimpact]

check your power supplies. try powering the moogers on a different outlet than the twin, if you haven't already. ground issues with music gear are often the culprits behind such infuriating noise.

[eric coleridge]

I've also experience ground hum, interference, and complete non-functionality with my Moogerfoogers in conjunction with other equipment. I've been told that the factory wall transformers are not grounded in the standard way as most other music equipment. I can't be more specific than this because I don't know enough about it, but I'm just reporting from my experience. If anyone can else can comment on this, I'd appreciate it.

[tboned]

check your power supplies. try powering the moogers on a different outlet than the twin, if you haven't already. ground issues with music gear are often the culprits behind such infuriating noise.

From your responses and some other reading, I'm thinking I either need to do that brass plate modification mentioned in asd's linked thread above, or I need to somehow improve the grounding for the wall sockets in my house. I've tried most of the sockets around the house, and the noise is always the same.

I've been told that the factory wall transformers are not grounded in the standard way as most other music equipment.

Just to clarify, by "factory wall transformers", you refer to the wall socket, yes?--(not a power strip or something else?)

How can I figure out if the problem is my wall sockets or my MF101?
If it is the wall socket, how should I rectify it? I read about sending a ground to earth with a stake into soil. Is this a good way to go, or overkill? I don't have a studio so to speak, but I have band practice at my house, so might I want to play it safe with that much equipment running at the same time?

Does the noise you get change with the control setting of the MF101? Maybe this could give a clue.

Maybe slightly higher pitch with higher control setting, but it's pretty much the same. Volume wise , it's definitely the same.

[Dr.T]

It remains difficult to diagnose the problem from afar. If there is so little change with a control change on the 101, I would suggest it's some kind of oscillation problem which could be due to a connection issue or to a power supply problem and further aggrevated by grounding problems. I am not really qualified to give any kind of opinion on the grounding problems you might or might not have in the the U.S. because my experience relates mostly to European power supply systems.

So I'll have to shut up. Nevertheless good luck with the MF-101 and the Twin - they'e both great tools!

Regards,

T.