• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Problem with the SWR Marcus Miller pre-amp

U

Uncle_Buck

Mar 20, 2007
5
0
#1
I bought an SWR Marcus Miller pre-amp a few weeks ago and, while the tone is great, it has a particular problem and I wondered if anyone else has experienced the same issue.

Basically, when any mains powered (9v adapter style) or battery powered effects are plugged into the effects loop it makes a dreadful hum. I've had my effects board checked out and there are no problems there, I have several other amps and it works with them no problem. I went through every possible configuration to make sure it wasn't a cable or connection of any kind.

The unit has been sent back to SWR/Fender and they don't appear to be able to fix the problem but they now know it exists.

Has anyone else seen this issue?

Cheers

Mike G. :confused:
 
#3
It has been my experience that using an effects loop for pedals always results in crazy noise.

Do you get that same noise with a rack effect (that doesn't have long cables)? Do these same fx sound find plugged in directly (as in Bass > FX > preamp)?
 
#5
Uncle_Buck said:
I bought an SWR Marcus Miller pre-amp a few weeks ago and, while the tone is great, it has a particular problem and I wondered if anyone else has experienced the same issue.

Basically, when any mains powered (9v adapter style) or battery powered effects are plugged into the effects loop it makes a dreadful hum. I've had my effects board checked out and there are no problems there, I have several other amps and it works with them no problem. I went through every possible configuration to make sure it wasn't a cable or connection of any kind.

The unit has been sent back to SWR/Fender and they don't appear to be able to fix the problem but they now know it exists.

Has anyone else seen this issue?

Cheers

Mike G. :confused:
Click to expand...

a VERY common problem; there is nothing wrong, aside from an odd number of grounded appliances. You need to clip the ground (shielding) on the sending end of the cord coming OUT of the SEND of the effects loop - open up the phone plug, clip the shielding, close the plug. That should take care of it. You can also lift the ground on the power plug (wall wart), but that can cause other, potentially dangerous, issues, so do the first way first.

Effects boxes in the front end of an amp are for people who don't know any better...effects loops are for effects...ALL effects...period...rack-mount or otherwise...use it. A ground loop can happen even with $10,000.00 Eventide rackmount units.

Good articles for those ignorant on the use of effects loops; Go here:

[Invalid or Expired Link Removed]

download the owners manual; read the addendum...all of them...read them many times if you have to (I did)...it is PACKED with great information on running balanced, unbalanced, and pseudo balanced rigs. It gets quite technical at times, and I wasn't being facietious about reading it several or even many times; for most of us mortals, it will take that many times to fully understand it all. Fabulous, well-written, highly informative stuff, and essential knowledge, ESPECIALLY if you are still plugging your effects pedals into the front-end preamp of an amp that's got an effects loop...!?

:rollno:

Why do you think they put them there?

RickenBoogie said:
Most stomp-box type effects pedals are designed to go in the front of the amp, (main inst. input), and NOT the effects loop. Try using them as intended, see if your problem goes away.
Click to expand...

No they're NOT...

Cheers,
Cameron
 
#6
Bassflute said:
..effects loops are for effects...ALL effects...period...rack-mount or otherwise...use it.
Click to expand...

No they're not. Many effects pedals work much better at instrument level, not consumer or pro line level. The vast majority of stomp boxes perform best between instrument and amplifier. If you don't believe this then look up the nominal voltage specs for FX sends.

In fact if it were not for effects loops also acting as handy preamp outs and power amp ins, I would suggest abolishing them entirely now that rackmount effects have long fallen out of favour.

Alex
 
#8
Bassflute, sorry, but you are misinformed. As stated above, stomp boxes, (the vast majority), are instrument level devices. Effects loops in amps are line level. Intended to be used with line level rack effects. Stomp boxes, (most of them) should be put in front of the amp, NOT in the loop.
 
#9
DI don't use effects any more, but I always got a much better sound out of my chorus pedal running it through the loop as opposed to in front of the amp. I guess this really doesn't help the OP though. :D
 
#10
As others have stated there is nothing wrong with your Preamp. You have a Ground Loop.

Also you need to consider when connecting pedals to your gear the greater number of pedals you have the worse your sound degrades including hum (especially if they are powered by a wall wart but not limited to) as well as other noises. Also remember do not judge the quality of your fancy Preamp with a 5 dollar pedal hooked to it. If your tone sounds like 5 bucks, it's the pedal. :eek::)

Congrats on the SWR M2 Preamp IMO the best Bass Pre out there.
 
#12
RickenBoogie said:
Bassflute, sorry, but you are misinformed. As stated above, stomp boxes, (the vast majority), are instrument level devices. Effects loops in amps are line level. Intended to be used with line level rack effects. Stomp boxes, (most of them) should be put in front of the amp, NOT in the loop.
Click to expand...

Last time this subject came up, a gentleman from EBS came on and stated MOST pedals these days split the difference between line and instrument level so they can be used at the front or in an effects loop. He also stated that they recommend putting them in the effects loop, as they will run optimally there - in the front of the amp, they will be noisy and 'weaker', I believe was the term he used. Also, you're putting everything BEFORE the tone controls, which is not great usually, except in the case of distortion boxes if they don't have their own tone controls.

alexclaber said:
No they're not. Many effects pedals work much better at instrument level, not consumer or pro line level. The vast majority of stomp boxes perform best between instrument and amplifier. If you don't believe this then look up the nominal voltage specs for FX sends.

In fact if it were not for effects loops also acting as handy preamp outs and power amp ins, I would suggest abolishing them entirely now that rackmount effects have long fallen out of favour.

Alex
Click to expand...

So you advocate preamping all the noise pedals generate, as well as putting all your effects BEFORE the tone controls and onboard compressor if your amp has one...and the abolishment of effects loops...AND you're a bass equipment manufacturer?

:(

:scowl:

:confused:

:eyebrow:

:rollno:

I certainly won't be buying any of your gear anytime soon...that's simply astonishing...breathtakingly ignorant...

Eric Moesle said:
True, most pedals are designed for INSTRUMENT level input and not LINE level as with an effects send.

While there are certainly some pedals that can function within an effects loop on line level, most sound better - and are less noisy - using the input voltages they were designed for.
Click to expand...

No, they can operate quite comfortably in both realms; how much difference is there these days between line level and what an active bass puts out...? Not much. The 18 volt Bartolini systems that I've used for 15 years or more can put out MORE than line level. Manufacturers have to take this into account, and especially BASS effects manufacturers - modern basses can have HUGE output.

Just because the average 15-year-old metalhead daisy-chains a bunch of effects into the front end of an amp doesn't mean it's the optimal way of doing it. Manufacturers make allowances for people doing that. It doesn't mean it's good.

jjk2007 said:
DI don't use effects any more, but I always got a much better sound out of my chorus pedal running it through the loop as opposed to in front of the amp. I guess this really doesn't help the OP though. :D
Click to expand...

+1,000

Red Planet said:
As others have stated there is nothing wrong with your Preamp. You have a Ground Loop.

Also you need to consider when connecting pedals to your gear the greater number of pedals you have the worse your sound degrades including hum (especially if they are powered by a wall wart but not limited to) as well as other noises. Also remember do not judge the quality of your fancy Preamp with a 5 dollar pedal hooked to it. If your tone sounds like 5 bucks, it's the pedal. :eek::)

Congrats on the SWR M2 Preamp IMO the best Bass Pre out there.
Click to expand...

Some good common sense there...

Eliminate effects loops....:rollno:

Unbelievable...that's THE most ignorant thing I've heard around here in ages...

I'm outta here...read the Aphex manual, and try "learnin' sumpthin"...

Cheers,
Cameron
 
#13
I think it's pretty clear that some pedals do better in front and some do better in the loop. This is why people do it both ways, not because they are all idiots.

It's no call for ridiculous forum warrior posing either way so knock it off.
 
#14
Yep. Stomp boxes are all over the map in terms of output and headroom, and also in their input capabilities. Some don't gracefully deal with much more input than a hot passive instrument can provide, others can deal with consumer line levels. Impedance design at either end may be suspect... I've seen a few preamps or channel strip units that give variable or switched control of level - but maybe only a couple that have both input and output matching controls.

There's a reason a lot of people don't have good luck using preamp loops, and it's not just because of ground loops.
 
#15
Bassflute said:
So you advocate preamping all the noise pedals generate, as well as putting all your effects BEFORE the tone controls and onboard compressor if your amp has one...and the abolishment of effects loops...AND you're a bass equipment manufacturer?
Click to expand...

Bassflute said:
I certainly won't be buying any of your gear anytime soon...that's simply astonishing...breathtakingly ignorant...
Click to expand...

Bassflute said:
Some good common sense there...

Eliminate effects loops....

Unbelievable...that's THE most ignorant thing I've heard around here in ages...

I'm outta here...read the Aphex manual, and try "learnin' sumpthin"...

Cheers,
Cameron
Click to expand...

:eyebrow:

You seem to have a few issues that need to be dealt with. Is there anything we can do Cameron?

We are here to help. :)


buh-bye.
 
#16
Bassflute said:
So you advocate preamping all the noise pedals generate, as well as putting all your effects BEFORE the tone controls and onboard compressor if your amp has one...and the abolishment of effects loops...AND you're a bass equipment manufacturer?

...I certainly won't be buying any of your gear anytime soon...that's simply astonishing...breathtakingly ignorant...
Click to expand...

I advocate doing what is best for your specific effects. The fact of the matter is that most pedals continue to work best in front of an amp at instrument level. There will be exceptions but that is the way it is, due to input and output impedances and maximum input and output voltages and noise thresholds. Although that Aphex manual is useful for that product it is not actually relevant to 99% of stompboxes which work on completely different impedances and nominal voltages. Sorry.

Alex
 
#18
alexclaber said:
Although that Aphex manual is useful for that product it is not actually relevant to 99% of stompboxes which work on completely different impedances and nominal voltages. Sorry.

Alex
Click to expand...

You obviously haven't read it. For someone advocating the abolition of effects loops, you should.

Cameron
 
#19
I must agree there are a lot of reasons one wants an FX loop. Most any good equipment should have at least one and really most should give us the series/parallel option.

On the SWR M2 Preamp I occasionally would hook up an old Art Multiverb III which is noisy as all get out, the extremely nice loop in the M2 made it quiet. Though the MVIII has level for input and output which allowed for good gain matching.
 

Latest posts

Top Bottom
Back