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How do I check if my Les Paul's overclipping?
by mirflee on 2012-06-10 22:42:59.8330


I'm having that odd harsh problem with the HD when I use it with a Marshall JCM live. I've searched and found out that my guitar could be the problem, giving too much of an output for the HD to run. So, how can I tell if my guitar's overclipping the HD's input?

Also, I've tried the suggestions from MeAmBobbo's HD guide, change the input settings, played around with the cabs, mics, output modes and the 'Presense' knob on the JCM and have come to this conclusion instead.

Looking forward to the replies,



Re: How do I check if my Les Paul's overclipping?
by Rowbi on 2012-06-11 01:20:29.3260

to check it properly, you'd need some special gear.  but a simple way is to hook up a digital multimeter to one end of a guitar cable, and have the other end of the cable connected to your guitar.  set the multimeter to a 'hold' setting while measuring mV.  then play as hard as you usually play with the guitars volume at max.  test this with every pickup combination too.  if the reading on mV goes off the scale just set it to a low volts setting, like 20 volts.

also read the output section here:

for some more ideas on how hot pickup output 'can' be...

but realistically, it's quite hard to discover what an acceptable maximum pickup output voltage should be soe every piece of gear.

this thread may help understand that there's lots of correct and also misleading info out there:

in short the way I'd look at this is do the test I've suggested above on a guitar that's giving you issues, and on another guitar that's not.  compare teh results and a very slight lowering of your pups on your LP may resolve this without really affecting your tone.

another way is to juct check that you're hearing the same thing when you play your POD HD through headphones.  if it's not there when using phones, then it's likely something such as the output level going into your JCM.  are you going into an FX loop return on the JCM?  If it's one with a loop level, is the level set to line (+4v) and then the POD needs setting to line and not amp... I know this sounds odd as you are connecting to an amp, but instrument level (amp) is -10v and is what the guitar input on the front of the amp will expect to see.  you can use this into a loop return on the JCM if you set that return input to instrument level (-10v), but line on the POD and +4v on the JCM would be best.  Marshall aren't that great at telling you that, they often just say on some of their amps 'loop level' and the handbook tells you not much more.  if your POD is set to line output, try the loop level settings on the head, and one will sound good and the other likely wont.  let your ears decide.

hope this helps.


Re: How do I check if my Les Paul's overclipping?
by mirflee on 2012-06-11 01:38:43.0700

Superb! Thanks so much for that very detailed post sir. I'll surely give your suggestions a go.

Yes, I'm bypassing my JCM's preamp and using the modelled amps from the HD thus running it through the FX Return. I've never checked the back end of the JCM for the loop level. Will do now. Anyway, I had the FX Loop mix knob on full for the JCM. Am I doing it wrong?

Re: How do I check if my Les Paul's overclipping?
by Rowbi on 2012-06-11 04:10:50.4310

which JCM do you have?  there's so many different models starting with the JCM800 in the early 80's, through to the JCM2000 TSLs... then in the middle there's a few different types of 800, 900 and 2000, and I have several here with me, and they all have slightly different implementations of FX loop.

Re: How do I check if my Les Paul's overclipping?
by mirflee on 2012-06-11 05:34:14.1860

Hello again,

I don't own the JCM's cause during sessions, I would usually rent a studio down the road. Most of the time, they'd give me a Marshall TSL2000.

Re: How do I check if my Les Paul's overclipping?
by Rowbi on 2012-06-11 07:43:09.5600

ah I see.

here's what I've copied from the TSL100 user manual:


Effects Loop A & Effects Loop B


The TSL supports two effects loops, which can be used in a variety of


Loop A when used on its own, is the master loop for the amp and will

channel switch from clean to overdrive when you change channels,

allowing you to set the individual mix from the front panel Mix controls.

Loop B is the specific loop for using effects on the overdrive channels

(Crunch / Lead) and if used on its own will only provide effects when on

these channels, leaving the clean channel totally dry.

When Loop B is in use Loop A becomes available for use solely on the

Clean channel. This means that you can have two totally different FX

systems, one for clean and one for overdrive.

Each loop has its own ‘loop level’ pushswitch, enabling you to select the

right send and return levels to suit whatever effects system you are using.

With the switch ‘out’, the level within the loop is high (suitable for most

pro rack fx). With the switch ‘in’, the level within the loop is set at a

much lower signal level (suitable more for floor pedals or lesser spec’d

rack units).

Note: The loops are in parallel mode until the mix controls are at 10

when the loop converts to series mode. Also, remember that as the loops

are between the preamp and the power amp, this is NOT the place for

distortion type effects units.


I've highlighted in bold and underlined certain key points. 

i'd use loop A's return, and yes set the mix control on the front to max.  it doesn't matter which channel you use as that's all preamp switching that you wont be using in the Marshall.

line level is used for pro rack FX, so you want the loop A level switch out.

hope this helps


Re: How do I check if my Les Paul's overclipping?
by mirflee on 2012-06-11 22:11:30.9060

Thank you so much for that, really really helpful. Anyway, I'm gonna try it now and will report back if there's any hiccups.

Thanks again!

The information above may not be current, and you should direct questions to the current forum or review the manual.