More bass from an 18 watter?

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Mark1406
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More bass from an 18 watter?

Post by Mark1406 »

I have used my 18 watter for a long time, but there are occasions when using single coil guitars (Strat) that I think it could use more bass.

I don’t know if the output transformer will allow a bigger bass response, I suspect I would need a transformer with a larger stack. That said I have thought of increasing the caps to the output stage from 0.01uF to 0.022uF or 0.047uF. I suspect I would have to go to 0.1uF to hear a difference and given the output transformer is part of the problem I might not like what I hear.

Amp has the parallel triode mod, the normal channel tone control mod and I reduced the plate resistor on the normal channel as the extra gain sounded a bit muddy, and I liked the sound of the amp with a shared 50K plate resistor (sure it could all be in my head, but I like it.)

Any thoughts?

Regards

Mark
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Bieworm
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Re: More bass from an 18 watter?

Post by Bieworm »

The coupling caps on the PI won’t make a lot of difference for bass..only mud.
You could raise the value on the coupling caps on the first gain stage though… I found going to .022uf in my first 18w build quite good for more bass.
Post a schematic of your build…
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Mark1406
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Re: More bass from an 18 watter?

Post by Mark1406 »

Thanks for the tip. The amp has some of Richie Hall’s mods in it. Other than that it’s stock.
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Mark
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Re: More bass from an 18 watter?

Post by Bieworm »

Mark1406 wrote:
Thu 04/06/23 1:44 am
Thanks for the tip. The amp has some of Richie Hall’s mods in it. Other than that it’s stock.

4A3A331A-3AD6-4905-A4F5-8FA957CC38E8.jpeg

Regards

Mark
that's not the schematic, it's a layout... I can't see the values of the coupling caps on this document...
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Re: More bass from an 18 watter?

Post by JMPGuitars »

Increasing the value of your coupling caps might help, however, it might also cause other issues when overdriving with other guitars.

You can also try increasing the cap value on the tone pot.

I would take a look at the bright/fat switch from the Superlite TMB: files/JMPGuitars_18_Watt_Superlite_TMB_Schematic.pdf

What speaker are you using with this amp?

The OT is probably not your limiting factor here. Chances are, it will handle more bass than the circuit will. Some users have modified their circuits to reduce the bass. Sometimes for tone, sometimes because the distortion gets muddy, etc.

The biggest factor is often the speaker and/or cabinet you're using. Then the V1 cathode cap, and the coupling caps following it, then the tone knob/stack.

If you feel like you don't have enough bass with only one guitar, then it's not the circuit that's lacking; you're trying to increase the bass in the circuit to make up for the guitar. You have to be careful in this situation so that there isn't too much bass with other guitars. That's why I think starting with a bright/fat switch is the best option.

Thanks,
Josh
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Re: More bass from an 18 watter?

Post by Mark1406 »

Thanks for your reply.

I run two speakers in series a Celestion Blue and a Celestion H30.

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Mark
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Re: More bass from an 18 watter?

Post by JMPGuitars »

Mark1406 wrote:
Thu 04/06/23 8:45 am
I run two speakers in series a Celestion Blue and a Celestion H30.
Both of those are on the brighter side, though I personally enjoy the Blue clones with 18W amps. Try the bright/fat mod and see how that works for you.
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Re: More bass from an 18 watter?

Post by Bieworm »

When I built the SL TMB once I had a DPDT switch which switched the extra cathode bypass cap in, and at the same time it switched the coupling cap from .01uf to .022uf. I found the match with .01uf better in the normal position instead of the .022uf. I found the SL overly fat with a .022uf coupling cap… to my taste 😎
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Re: More bass from an 18 watter?

Post by Mark1406 »

JMPGuitars wrote:
Thu 04/06/23 9:44 am
Mark1406 wrote:
Thu 04/06/23 8:45 am
I run two speakers in series a Celestion Blue and a Celestion H30.
Both of those are on the brighter side, though I personally enjoy the Blue clones with 18W amps. Try the bright/fat mod and see how that works for you.
Thanks for your help.

I looked around the site for the bright/fat mod and couldn’t find any thing. I have two other speakers in other amps. I will try the amp with those speakers.

I did play bass through my 18 watter and it didn’t like it at all. I have a Champ with a Mercury Fatstack output transformer that was louder than it.

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Mark
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Re: More bass from an 18 watter?

Post by JMPGuitars »

Mark1406 wrote:
Thu 04/06/23 5:12 pm
I looked around the site for the bright/fat mod and couldn’t find any thing. I have two other speakers in other amps. I will try the amp with those speakers.

I did play bass through my 18 watter and it didn’t like it at all. I have a Champ with a Mercury Fatstack output transformer that was louder than it.

Regards

Mark
I gave you a link to the schematic above:
JMPGuitars wrote:
Thu 04/06/23 8:28 am
I would take a look at the bright/fat switch from the Superlite TMB: files/JMPGuitars_18_Watt_Superlite_TMB_Schematic.pdf
Trying the other speakers is a good idea anyway.

Thanks,
Josh
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Re: More bass from an 18 watter?

Post by Mark1406 »

I will continue to try different speakers, but so far different speakers have different timbre but not more bass response.

I tried increasing one of the 103 caps in the normal channel, it didn’t increase the bass as much the mids. It wasn’t an unpleasant sound.

Thanks again for your assistance.

Regards

Mark
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