PRS Custom 20

godwentpunk

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May 16, 2018
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I recently picked up playing this combo again after playing my Marshall JVM combo over the last year. I noticed that the PRS sounded a little thin and boxy (almost solid state like) on the lead channel. For those with this amp, is this typical? or am I in need of new tubes.. I put in a couple different speakers but nothing sounded quite right. I checked the bias and it was set at 28/30 which seems to be typical for this amp, I might push the bias up to 33 but I don't think that will fix the boxy sound. The clean channel sounds much better, but it still sounds like it's holding back. The low end on the amp also feels like it's missing something which might be the root cause of things. I am playing a little louder than bedroom volumes but certainly not band levels.

Or is it just that my ears are now Marshall trained?? but over all of the combos I have, this amp definitely sounds like something might be going on.

Any feedback will be welcomed.

thanks!

joe...
 
I had one, great amp but it’s not a Marshall. Also when in doubt I throw new preamp tubes in, they are relatively cheap and then you’ll know. As for ‘boxy’ it is 20 watts in a small 1x12 cab and won’t thump like a Marshall, but I liked the gain side of the amp, just wasn’t saturated enough for my taste.
 
How far are you turning it up? The master volume on the lead channel needs to be up above 9:00 for that amp to really sound good.
 
It’s awfully easy to tell if it’s the power tubes. Try a new pair.

Preamp tubes last for many years, unlikely they’re your problem, but power tubes will wear out.

When I was a Two-Rock player, I was advised to change power tubes every six months, give or take. Also Squid makes a good point; PRS amps are usually at their best run with the Master as wide open as you can stand, using the gain control old school, as a volume control.

I run my single channel PRS amps with the masters up past noon, usually around 2:00.
 
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Definitely try new tubes, the lead channel of the Custom amps are anything but “boxy,” usually the bass is very sufficient. Also, you can use the depth push/pull on the presence knob for more low end.
 
Plus, it’s hard to really know what someone means when they say “boxy.” These models are known for having a lot of bottom end. Many think too much unless you turn the bass knob way down. I would have guessed it was too much bottom maybe making it a bit to boomy in the bottom, but you say it’s lacking something in the bottom end, compared to Marshalls which are light in the low end.

Turn the bass knob down. Turn the master up a bit. If the amp doesn’t open up, it needs tubes somewhere. IMHO
 
I'm really not running the master very loud at all, maybe that is the problem. I did pull the MID and the PRESENCE pot which helped a little with the bass response on my lead channel... which at the moment, has the bass set to full open. Now, the clean channel does have some better low end since making those 2 setting changes and now I have to on the clean channel turn down the bass.

My issues might as well be from a need to learn more about the tweakingness of the amp because I've noticed turning a knob 10% makes a huge difference in its tone.

I appreciate everyones input!

joe...
 
Joe,

What you're describing sounds pretty normal for that amp, if you're trying to keep it quiet.

It's a tube amp and the fact of the matter is that it loves to be loud. Find or make an opportunity to turn all the knobs on the lead channel to noon and let her rip! This will make your ears ring, but it should be anything but thin and boxy (I did this a few minutes ago and it was glorious). Then start working the knobs to season to taste.
 
Joe,

What you're describing sounds pretty normal for that amp, if you're trying to keep it quiet.

It's a tube amp and the fact of the matter is that it loves to be loud. Find or make an opportunity to turn all the knobs on the lead channel to noon and let her rip! This will make your ears ring, but it should be anything but thin and boxy (I did this a few minutes ago and it was glorious). Then start working the knobs to season to taste.

So I turned things up and give myself a ear-ringing night... but yeah, when played loud, it certainly is not boxey at all. It is still a very tight amp which I link but I think I prefer a more vintage (open) sounding amp.

I have a band practice (hopefully) at the end of the week and I'm going to bring this amp along to see how I like the tone.

joe...
 
So I turned things up and give myself a ear-ringing night... but yeah, when played loud, it certainly is not boxey at all. It is still a very tight amp which I link but I think I prefer a more vintage (open) sounding amp.

I have a band practice (hopefully) at the end of the week and I'm going to bring this amp along to see how I like the tone.

joe...

I'll start the bidding at $500. :D So, if by "more open sounding" you mean less compressed and brighter, open up the master, turn the gain down, and turn the presence up a lot then adjust the treble content with the treble knob. Bass down low. I'm going by what worked on the C50.
 
So, if by "more open sounding" you mean less compressed and brighter, open up the master, turn the gain down, and turn the presence up a lot then adjust the treble content with the treble knob. Bass down low. I'm going by what worked on the C50.

I'll give your suggestion a try this week.

thanks for help me with this.

joe...
 
I have another question. I went to use my amp last night and the solo boost was not working. The light does toggle on the footswitch but I'm not getting any volume difference. I moved the knobs around on the back but that didn't help either. Could this be an issue with the footswitch or the amp? Is there anyway to test the boost by passing the footswitch??
 
I have another question. I went to use my amp last night and the solo boost was not working. The light does toggle on the footswitch but I'm not getting any volume difference. I moved the knobs around on the back but that didn't help either. Could this be an issue with the footswitch or the amp? Is there anyway to test the boost by passing the footswitch??

Two things to try. Unplug the footswitch and then plug it back in. After that, stomp the boost switch multiple times. I mean on,off,on,off over and over. Footswitches are the number one biggest issue that pedal makers have, parts wise. David Barber told me one time that almost every single part failure he had over the years was footswitches. And many times, when they stop working correctly, multiple quick switches will make them work fine again.
 
Two things to try. Unplug the footswitch and then plug it back in. After that, stomp the boost switch multiple times. I mean on,off,on,off over and over. Footswitches are the number one biggest issue that pedal makers have, parts wise. David Barber told me one time that almost every single part failure he had over the years was footswitches. And many times, when they stop working correctly, multiple quick switches will make them work fine again.

Thanks for the heads-up... So I did as you suggested and my boost is working today. I'm not sure why just the boost switch was acting up but I hope it was a one time thing. Is anyone aware of footswitches from a different manufacturer that might work?

joe...
 
I'm late to the thread, but found it interesting. I used to play a JVM 410. Monster of an amp. Loved it, but I thought it had little bass end, even cranked through a 2x12. I also found it to be a little over the top on compression and sometimes a bit "ice-picky". I dumped it because of its weight and I just don't need 100 watts.

Twenty to thirty was more to my liking to match my gigs and I ended up with the PRS custom 20 because it's feature rich for a low wattage amp; channel switching, effects loop, boost, independent eq, stuff you only get in bigger, higher end amps. I got the head and pair it with a DV Mark 2x12 with the neo-dyn speakers - very easy on the back.

I find amp to have plenty of gain but less compressed, more "lose" or "open" than the JVM. It also has almost too much bass. Even at 20 watts when I have this thing at 12 it's very loud, very beefy.

Interesting that different folks can have different perceptions of (nearly) identical pair of amps.

--chuck
 
I find amp to have plenty of gain but less compressed, more "lose" or "open" than the JVM. It also has almost too much bass. Even at 20 watts when I have this thing at 12 it's very loud, very beefy.

Interesting that different folks can have different perceptions of (nearly) identical pair of amps.

--chuck

Cabs, speakers, the room, and where the cab is in relation to the floor and walls make ridiculous difference in how an amp will sound. My Custom 20 combo sounds like a different amp if it's sitting on a stand or another amp, compared to when it's on the floor.
 
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