Randall RH200 amp cut out while palm muting

[metalbeast]

Hey guys,

Saw there was a post back in 2009 about the Randall RH200 cutting out. But no real solutions given.

My RH200 was doing the same thing. When I palm mute power chords, the sound would just stop for a millisecond, then come back on .....someone told me, "Oh. That must be the capacitors going out. How many hours do you have on the amp?" Not knowing how many I had logged, nor those who had it before me, I couldn't accurately answer that.

I went and bought another one, (for about half of what I got the first one! lol), and guess what? Yup. Same thing. I have an MXR-108 10 band eq at the end of my pedal board....as a test, I dropped the sliders on the last two bass freq. and it "sorta" went away.....so this tells me its a frequency issue? I'm running through two 4x12 cabs at 8ohms.

I keep hearing about a "limiter circuit" thing....is there any validation to that? It seems to not make a difference whether it's 4ohms or 8ohms. 460watt 4x12 cab, or 860watt 2x 4x12 cabs @8ohms for each.....no one seems to know what the deal is, and the guys at Randall now, weren't there when the heads were made, and so have no real idea about the issue for this head......HELP!

[joecool85]

Sounds like a noise reduction feature.  Not sure about on your Randall, but on my Vox AD50VT I can adjust the Noise Reduction and if it is up too high it acts exactly like you are describing.  Do you have the manual for it?

[metalbeast]

Hey Joecool85, yeah.......downloaded it from Randall's site....but it doesn't say anything about that. 

The back of the amp has two inputs. One for 4ohms, and one for 8ohms......it does it in both. Whether I daisy chain them together or plug them in separately, (meaning top cab into one input, bottom into the other.)

Seems odd that it would be a frequency issue......it can push 200watts at 8ohms, or 220watts at 4ohms. I thought that 4ohms was easier on the amp.....am I wrong on that?

[joecool85]

Hey Joecool85, yeah.......downloaded it from Randall's site....but it doesn't say anything about that. 

The back of the amp has two inputs. One for 4ohms, and one for 8ohms......it does it in both. Whether I daisy chain them together or plug them in separately, (meaning top cab into one input, bottom into the other.)

Seems odd that it would be a frequency issue......it can push 200watts at 8ohms, or 220watts at 4ohms. I thought that 4ohms was easier on the amp.....am I wrong on that?

4 ohms is actually harder on the amp, the chips will get hotter etc.  That said, as long as it is rated for it that's fine.  None of that has to do with your issue though.  This sounds like a preamp issue to me.

[metalbeast]

Is there any way to check that?? And would it do the same thing on two of the same amps? I saw in a post back in 09 that someone suggested running a volume pedal through the effects loop in the back of the head.? Not sure what good that would do.....I usually run the master at about 2-2 1/2 and the channel to about 2-4. Not much past that.....most of the time it is being mic'd. I'm really stumped on this. The guys at Randall are not much help. 

[J M Fahey]

I won't say that it's poorly designed, because it's not so, but maybe the designers didn't test it with such heavy palm muting as you are using.
It sounds to me that some stage in the preamp is blocking for a few milliseconds when hit with that "sonic hammer".
Are you using some pedal to drive it?
Send somewhat less bass into the Randall.
Does it happen on both channels?
That the problem is inherent to the design is proven by it happening on both, but something you use on both might also be the culprit.
It's not the first time that I heard somebody complain about something similar and it turned to be a weak battery somewhere in his signal chain.
What happens if you lower the Master volume?
Or maybe the speaker doesn't like so much bass.
In a nutshell: personal opinion, it's in the (pre)amp, it's "normal" , you may minimize it by carefully choosing what you feed into it.
A schematic would be the only way to advance further.
Ask them, providing your serial number(s), say your technician needs it (which is true).
Good luck.

[metalbeast]

Hey JM, thanks for tagging on this.

I use the Dragonfly BM-1 Black Metal Pedal, (distortion pedal), through the clean channel only, (the dirty channels leave something to be desired....lol). On the amp itself, we lowered the bass, mid and treble, (down to like 2), due to the MXR 10 band eq at the end of my pedal chain. I use the Pedal Power 2 power supply to power up the pedals..."Batteries?! We no need no stinkin' batteries!" 

At practice last night, (with the eq's on the head turned down to like 2), it did cut out once. for a nanosecond! But not the rest of the night.......we have a song that is heavy palm muting throughout the song, and it didn't do it once during that song. (BTW we are a Black metal/Death metal band.....) So sometimes it does.....sometimes...... :loco

I keep the volume slider on the MXR 10 band eq low......basically cracked and that's about it. Volume on the BM-1 at about 3. Amp Master about 2-2 1/2 and the channel approx 3-4.

Top cab is 8ohms at 400watts. Bottom cab 8ohms at 460watts. Head 200watts at 8ohms, or 220watts at 4ohms. I love the amp. It'll push sound quite a ways! And LOUD as all get out! Great for the venues that don't mic the cabs...

I'll try to hit up Randall for the schematics. I'm pretty sure that most of the guys that worked there when the head was made, (2000), are probably gone. Thanks for the help with this....this has been the first forum to actually lend a hand with this issue. Thanks guys.....any other thoughts on this will be greatly appreciated!  :tu:

[joecool85]

I keep the volume slider on the MXR 10 band eq low......basically cracked and that's about it.

This might be your issue.  Try turning that volume up a bit, turn down the amp's volume as necessary.  Also, make sure your guitar is turned all the way up on volume.

[metalbeast]

Hmmm.....that's an idea....thought that maybe the "effects" volume would be "too" much for it to handel, but, if the amp volume is adjusted accordingly, then it should even out.....we'll know Wednesday at practice.....thanks joecool85!

[joecool85]

Hmmm.....that's an idea....thought that maybe the "effects" volume would be "too" much for it to handel, but, if the amp volume is adjusted accordingly, then it should even out.....we'll know Wednesday at practice.....thanks joecool85!

Let us know.

[metalbeast]

k, so it's Thursday morning, and I have news......I turned the amp master volume down to 1, and the channel to about 2. The slider volume control on the MXR 108 10 band eq we set to just a crack above the "0" or "neutral" mark. WOW! What a difference!! LOUD! VERY LOUD NOW! I asked the drummer if he could hear me ok, and he said I could come up a bit....so the channel volume on the amp went to 3.  master stayed at 1. What a difference! Joecool85, I think you've hit onto something with this...... see, I was told that the volume on the effects pedals are to be low, and crank the amp. In this case, it looks like this is the opposite. Or.......?

Is it because it it an eq, and not an "effects" pedal? Although, to me, it it is still "affecting" the sound.....a little more than confused here, but pleased that there was no results of cutting out. In my mind, end result. I would call it a win. I will do more fiddling around with this on Friday as well......thanks guys!

[joecool85]

k, so it's Thursday morning, and I have news......I turned the amp master volume down to 1, and the channel to about 2. The slider volume control on the MXR 108 10 band eq we set to just a crack above the "0" or "neutral" mark. WOW! What a difference!! LOUD! VERY LOUD NOW! I asked the drummer if he could hear me ok, and he said I could come up a bit....so the channel volume on the amp went to 3.  master stayed at 1. What a difference! Joecool85, I think you've hit onto something with this...... see, I was told that the volume on the effects pedals are to be low, and crank the amp. In this case, it looks like this is the opposite. Or.......?

Is it because it it an eq, and not an "effects" pedal? Although, to me, it it is still "affecting" the sound.....a little more than confused here, but pleased that there was no results of cutting out. In my mind, end result. I would call it a win. I will do more fiddling around with this on Friday as well......thanks guys!

Yeah, sounds like it wasn't the amps fault at all.  It was getting such a low peak to peak voltage signal that it was exhibiting weird behavior.  I normally keep my pedals set at parity.  That means it is the same volume whether the effect is on or whether I'm plugged straight into the amp.  On most pedals I use this is around 1/2 on the volume control - some as low as 1/4, some as high as 3/4.