Low end clipping on SL 18 conversion

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JimbpGaff
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Low end clipping on SL 18 conversion

Post by JimbpGaff »

Hi
I have just modded an Ampmaker 18watt lite to a SL 18 and it works fine apart from some clipping when I pluck the low E string hard with a medium to high gain setting.
Sounds great on lower gain settings and it must be in the preamp section as I have installed a passive loop and when I feed in my 800 preamp, it works fine.
Thanks Jim
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Re: Low end clipping on SL 18 conversion

Post by zaphod_phil »

I suspect you need to apply the Paul Ruby mod
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JimbpGaff
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Re: Low end clipping on SL 18 conversion

Post by JimbpGaff »

Thanks for the info Phil, where can I find details of the mod?

Thanks Jim
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Re: Low end clipping on SL 18 conversion

Post by JMPGuitars »

I've included the mod in the new Superlite docs: viewtopic.php?f=25&t=24430

Thanks,
Josh
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JimbpGaff
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Re: Low end clipping on SL 18 conversion

Post by JimbpGaff »

Thanks for all your help chaps.

Do you think I should try the diodes first?

Jim
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Re: Low end clipping on SL 18 conversion

Post by Bieworm »

JimbpGaff wrote:
Wed 04/29/20 4:46 pm
Thanks for all your help chaps.

Do you think I should try the diodes first?

Jim
The diodes won't make any difference.. it's the zeners that do the job. I have 15V ,1.5 Watt zeners in mine. So easy and... man what a difference!
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JimbpGaff
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Re: Low end clipping on SL 18 conversion

Post by JimbpGaff »

I have ordered some .

Any idea why I had the problem in the first place?
Jim
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Re: Low end clipping on SL 18 conversion

Post by Bieworm »

some here understand entirely what's the theory behind this matter... some don't (like me)
from what I can understand it has to do with crossover distortion. I also know that that "great 18 watt sound" is partial due to having a teenieweenie bit of fizz on top of the overdrive. It's the sparkle in the sound, the shine of its soul ;) ... mine was over the top, the sparkle was more like a phaser when the amp was dimed. So performed the PR mod, and it's generally gone back to teenieweenie
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Re: Low end clipping on SL 18 conversion

Post by JMPGuitars »

You can learn more from the source: http://www.paulamps.com/18watterbuzz.html
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Re: Low end clipping on SL 18 conversion

Post by zaphod_phil »

Bieworm wrote:
Thu 04/30/20 4:31 am
from what I can understand it has to do with crossover distortion.
actually, it's blocking distortion. Crossover distortion is trivial by comparison and mainly of interest for hi-fi , rather than guitar amps.
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Re: Low end clipping on SL 18 conversion

Post by Bieworm »

zaphod_phil wrote:
Thu 04/30/20 11:00 am
Bieworm wrote:
Thu 04/30/20 4:31 am
from what I can understand it has to do with crossover distortion.
actually, it's blocking distortion. Crossover distortion is trivial by comparison and mainly of interest for hifi amplifiers, rather than guitar amps.
ZP.. you're not associating me with hifi nerds, are you? Just because I talk the talk, doesn't mean I walk the walk huh ;)
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Re: Low end clipping on SL 18 conversion

Post by JMPGuitars »

Bieworm wrote:
Thu 04/30/20 11:13 am
zaphod_phil wrote:
Thu 04/30/20 11:00 am
Bieworm wrote:
Thu 04/30/20 4:31 am
from what I can understand it has to do with crossover distortion.
actually, it's blocking distortion. Crossover distortion is trivial by comparison and mainly of interest for hifi amplifiers, rather than guitar amps.
ZP.. you're not associating me with hifi nerds, are you? Just because I talk the talk, doesn't mean I walk the walk huh ;)
lol, that's not what that means. HiFi nerds want to eliminate all distortion, but guitar amps would be boring and sterile without the correct types of distortion.
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Re: Low end clipping on SL 18 conversion

Post by Bieworm »

JMPGuitars wrote:
Thu 04/30/20 2:25 pm
Bieworm wrote:
Thu 04/30/20 11:13 am
zaphod_phil wrote:
Thu 04/30/20 11:00 am

actually, it's blocking distortion. Crossover distortion is trivial by comparison and mainly of interest for hifi amplifiers, rather than guitar amps.
ZP.. you're not associating me with hifi nerds, are you? Just because I talk the talk, doesn't mean I walk the walk huh ;)
lol, that's not what that means. HiFi nerds want to eliminate all distortion, but guitar amps would be boring and sterile without the correct types of distortion.
I knew that that's not the purpose of that saying..that's exactly why I used it. :)
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Re: Low end clipping on SL 18 conversion

Post by zaphod_phil »

Bieworm wrote:
Wed 04/29/20 9:35 pm
JimbpGaff wrote:
Wed 04/29/20 4:46 pm
Thanks for all your help chaps.

Do you think I should try the diodes first?

Jim
The diodes won't make any difference.. it's the zeners that do the job. I have 15V ,1.5 Watt zeners in mine. So easy and... man what a difference!
You actually need both for this mod. And yes, it works wonders!
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JimbpGaff
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Re: Low end clipping on SL 18 conversion

Post by JimbpGaff »

Carried out the diodes mod but unfortunaly it is still there.

It must be a issue in the preamp section up to the cap before the phase inverter.
I have fitted a passive loop ( the one from here ) into the amp and when I run my peavey Rockmaster in through there I can crank it and no clipping.
Also when running my guitar into the main input on a lower gain but with a boost in front, it makes it worse.
I am wondering if it may be a bad connection ?

As always, thanks for all your help.
I will et there in the end.

Jim
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