Old 05-31-2020, 05:23 PM   #1
toleolu
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Default Marshall Amp Hiss

Aloha, hope all are well.

I picked this amp up today off Craigslist, sounds great, but as this is my first Marshall, I wasn't sure about this loud hiss when I kick in the second channel.



The Classic and Ultra Reverb knobs don't appear to have much of an effect either. Stuff online says it's usually the preamp tubes, but I went through all that with a Traynor amp I bought a little while back, replacing the the tubes in that didn't fix the reverb.

Thanks
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Old 05-31-2020, 05:43 PM   #2
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I own a dsl40cr and that amp sounds like it needs to go to a tech. They are deadly if you dont know what you are doing. Did you plug a guitar into it?
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Old 05-31-2020, 06:03 PM   #3
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Thanks Coach, yes plugging a guitar in doesn't really seem to affect it.

Still sounds really good though. I have to turn the volume and gain down pretty low because of where I live, then when I do that the hissing goes away. I can crank it up pretty good on the Classic Gain channel and the hissing isn't that bad, it's when I switch to the Ultra Gain channel with it cranked up pretty good, the hissing gets bad.
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Old 06-01-2020, 01:13 PM   #4
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Quote:
Originally Posted by toleolu View Post
Thanks Coach, yes plugging a guitar in doesn't really seem to affect it.

Still sounds really good though. I have to turn the volume and gain down pretty low because of where I live, then when I do that the hissing goes away. I can crank it up pretty good on the Classic Gain channel and the hissing isn't that bad, it's when I switch to the Ultra Gain channel with it cranked up pretty good, the hissing gets bad.
Is the hiss louder than what you're playing? If you can't hear hiss when you play, that's normal. High and ultra gain preamp circuits are hissy. It's usually drowned out by the rest of the band.

Sometimes amps pick up strange hum from bad wiring or radio signals nearby. A power conditioner can help provide continuous, clean power and isolate your amp from stray noise.
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Old 06-01-2020, 01:31 PM   #5
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Tubes? If yes, could be a bad or cheap preamp tube...
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Old 06-01-2020, 01:34 PM   #6
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"That's just how you know it's loud"
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Old 06-01-2020, 01:39 PM   #7
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Once you play for a bit and drill that Marshall 2.5k whistle into your head you won't hear the hiss anymore. (You may also not hear many other things anymore!)

Last edited by serr; 06-01-2020 at 02:07 PM.
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Old 06-01-2020, 01:44 PM   #8
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Sounds like an amp with the gain cranked but that does seem a little loud, preamp tube a worthy suspect to rule out - I think it uses the very common 12AX7 so you could borrow three from another amp to test if you have one lying around since those are plug and play.

I don't suspect extraneous interference since that's thermal noise in the video. Marshal can be known for hiss due to gain - I've seen some chatter on the net of it being the unit itself but with tube amps, swapping out tubes is always step one so might as well get that question out of the way.
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Old 06-01-2020, 03:09 PM   #9
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I have the dsl40cr and the hiss level is low compared to the gain levels. If you crank it up to a insane deafening level there will be a pretty strong hiss floor but if you are just rocking out like normal then this is a pretty low hiss.
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Old 06-01-2020, 03:31 PM   #10
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Quote:
Originally Posted by Coachz View Post
I have the dsl40cr and the hiss level is low compared to the gain levels. If you crank it up to a insane deafening level there will be a pretty strong hiss floor but if you are just rocking out like normal then this is a pretty low hiss.
His settings in the video for that amount of hiss seemed potentially abnormal... Then again it's "ultra gain" which is the mostest gain there is so... I mean I cranked my boogie to max gain and max master output and it was nowhere close to what he had... but I don't have "ultra gain" <-- spoken with reverb and delay.
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Old 06-01-2020, 07:18 PM   #11
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There is a mod to help with that problem, that model has some history with that issue.

I forget what it was, but there's a forum dedicated to Marshall Amps that has a huge thread on that model.

It won't completely fix it, as it is inherent to that particular amp, but will quiet it down considerably for recording. Worked like a charm for mine.

If you need more help finding the fix feel free to p.m. me for details.

Peace
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Old 06-01-2020, 07:33 PM   #12
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Thanks to steveb93

EDIT: Or 63, or whatevs.... sorry....

Last edited by dug dog; 06-01-2020 at 07:34 PM. Reason: EDIT: Or 63, or whatevs.... sorry....
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Old 06-01-2020, 07:38 PM   #13
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Quote:
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Once you play for a bit and drill that Marshall 2.5k whistle into your head you won't hear the hiss anymore. (You may also not hear many other things anymore!)
Large LOLz( sp?)
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Old 06-01-2020, 10:37 PM   #14
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You need a Cock Blocker.


And no, I am not shitting you. You really need a Cock Blocker (or any decent FX loop based gate pedal) for those hi-gain amps.

https://www.gearnews.com/smg-cock-bl...hiss-in-check/
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Old 06-02-2020, 12:15 AM   #15
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Really appreciate all the suggestions.

I've been playing around with it and just using the normal gain the hiss isn't a problem. I'm micing it when I record, the tone is amazing. Hands down the best amp I've ever owned.

I'll check on that mod that Steve mentioned. I had checked on the Marshall forum and saw where it's not that uncommon, and I am basically just sitting right next to it.

I got it for 300 bucks so I think at some point I'll have a tech take a look at it.

Thanks to all.
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Old 06-02-2020, 01:36 AM   #16
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Quote:
Originally Posted by toleolu View Post
it's when I switch to the Ultra Gain channel with it cranked up pretty good, the hissing gets bad.
I've been a professional recording & live session guitarist for 35 years. This is absolutely normal behavior with an amp set on full "ultra" gain.
A distortion pedal on full will also give you the same sound and problem.

If anything, I'd suggest using the best high-quality shielded guitar leads you can afford. At ultra-high gain, any RF interference will be boosted.


Quote:
I'm micing it when I record, the tone is amazing. Hands down the best amp I've ever owned.

You got a great deal. Enjoy!
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Old 06-02-2020, 05:40 AM   #17
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I've been a professional recording & live session guitarist for 35 years. This is absolutely normal behavior with an amp set on full "ultra" gain.
It's not set on full though, gain is maybe 5.5. I'm tempted agree with you but none of my (10 or so) amps hiss like that with the gain half-way up and nothing plugged in. "Ultra" could be telling so I'm not saying that's not it, since I don't have that amp but as a fellow "lifer" using amps professionally since the 80s, I'd get rid of it if it hissed that much assuming...

We aren't hearing a pronounced version due to the phone/auto gain etc. However, hearing the foot switch kick in makes it seem like it really is louder than what normal should be. But then again, "ultra" so who knows. Still though we have to guess a bit with only that video to go by.
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Old 06-02-2020, 09:37 AM   #18
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I'm setting up to shoot a better video, post that once it's done.
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Old 06-02-2020, 11:26 AM   #19
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Hope this is a little better. I could only get to about 6 on the Gain in Ultra Gain before it started clipping and the wife started bitching.



The switch on the back was set to 20 watts, but even switching to 40 watts the hiss remains the same. Doesn't get louder when switched to 40 watts.
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Old 06-02-2020, 11:30 AM   #20
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You have the volume cranked up. I bet if you hit a single note at that setting, you'd blast your face off.

At a normal volume, that hiss will probably seem normal for that particular channel/configuration. It's fine. Higher gain amps have more noise. That channel has more gain stages.

The extra noise (hum) in that new clip: probably from interference of a nearby electrical device.
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Old 06-02-2020, 11:57 AM   #21
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Thanks James and yes, at least here in the man cave, I would never crank it that loud, and yes my acoustics here leave a lot to be desired.

The Classic Gain channel is not a problem, it's just when I switch it to the Ultra Gain mode that I was concerned about. To be honest, I really don't see myself using that mode as I use pedals (distortion, overdrive, compression, etc.) to give me the effects I want.

Still plan on taking it to a tech. The Channel Select button on the front doesn't switch channels, only works via the footswitch, and the Reverb doesn't seem to be working right.
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Old 06-02-2020, 12:56 PM   #22
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I just did your test with no input and cranking up the ultra gain on my Marshall dsl40cr amp and it creates a shit ton of hiss just like your demo did.

If I instead plug in my guitar with my ultra gain values set to 10 oclock both volume and gain and my master volume turned all the way up I can blow myself out of the room and the hiss level is quite low. How is yours with those settings with a guitar plugged in and hitting some power cords?
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Old 06-02-2020, 01:05 PM   #23
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I bet using overdrive pedals into the classic channel will yield a similar level of hiss, if your overall gain/distortion level is similar to using the ultra channel (without a pedal)...testing at the same overall volume level, of course (which you'd have to verify by hitting a note and comparing actual signal volume, not just the settings of the channel volume controls, since each channel may have different output volume at "the same" channel volume control setting).

For those other reasons I'd say it's worth having it checked out. But the hiss is normal. It's possible to lower the hiss by cherry-picking preamp tubes, but it's probably always going to be at that approximate level.
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Old 06-02-2020, 01:12 PM   #24
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Originally Posted by Coachz View Post
If I instead plug in my guitar with my ultra gain values set to 10 oclock both volume and gain and my master volume turned all the way up I can blow myself out of the room and the hiss level is quite low.
When you say Master Volume, is that different from the Volume knob on the Ultra Gain channel?
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Old 06-02-2020, 01:24 PM   #25
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I see that the dsl40c does not have the master volumes as the DSL40cr has so what I would suggest is to plug in your guitar turn up the ultra gain Gain to 10 oclock and the volume to 9 oclock. What is the level of hiss there and when you hit a power chord does it blow you out of the room?
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Old 06-02-2020, 01:35 PM   #26
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Originally Posted by Coachz View Post

If I instead plug in my guitar with my ultra gain values set to 10 oclock both volume and gain and my master volume turned all the way up I can blow myself out of the room and the hiss level is quite low. How is yours with those settings with a guitar plugged in and hitting some power cords?
I tried your settings, Ultra Gain channel, Gain knob at 4 (10 o'clock) and the Volume knob at 10, max.

https://www.dropbox.com/s/nlw7gplz6izj0z4/hiss.wav?dl=0

The first few seconds are no guitar plugged in, then the last is a strat with hot noiseless pickups plugged in. FYI, when I plug my PRS in, I get pretty much the same thing. I did kind of "bump" a few strings while it was cranked like that and oh baby!! If I hit a power chord, I'd be laying out in the yard.

Thanks again to all for the help.
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Old 06-02-2020, 02:41 PM   #27
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How about creating us another file at a volume level that sounds good to you playing some power cords and then stop every so often so we can hear the hiss level in between the power cords
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Old 06-02-2020, 02:55 PM   #28
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Classic Gain channel, clean, Gain at 2 and Volume at 9.

https://www.dropbox.com/s/k5ly8h70h4q0hiz/amp1.wav?dl=0
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Old 06-02-2020, 03:10 PM   #29
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Classic Gain channel, clean, Gain at 2 and Volume at 9.

https://www.dropbox.com/s/k5ly8h70h4q0hiz/amp1.wav?dl=0
Sounds fine. Now how about some power chords with gain on 4
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Old 06-03-2020, 08:45 AM   #30
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Sounds fine. Now how about some power chords with gain on 4
A power chord like the AC chord?

I really appreciate your time helping me with this Coach, great resource having someone with the same gear that I can compare my stuff with.

I recorded some stuff last night, most of the "noise" is my crappy acoustics, so for what I need to do, I think I'm good. Still going to take it to a tech though one of these days.

Taking to my friends house Saturday, gonna really blow it out then.

Stay safe all.
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