18 Watts and Clean tones

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ViperDoc
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18 Watts and Clean tones

Post by ViperDoc »

I wonder what gig-level, clean headroom could sound like in an 18-watt amp. I've come up empty researching a consensus on NFB, the "dookie mod", etc. Also, replacing the 470K PT grid leak resistors with 220K or lower, etc. I understand you can't have everything in one channel, but what is the agreed-upon solution? Blackface? I know it's not 18 watts, but a Fargen DBC has an excellent clean channel using EL34s. Is it possible with EL84s?
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Re: 18 Watts and Clean tones

Post by garakin »

I would probably go after those two areas first to bump head-room before I went anywhere else to make mods. Perhaps wire the NFB on a pot to pull most of it out of the circuit (grit control?). I would make the grid leaks switchable between the stock and lower values.
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Re: 18 Watts and Clean tones

Post by JMPGuitars »

NFB is not what you want, it kills the 18W tone.

There's no reason you shouldn't be able to get enough clean tone from an 18W amp. If you need more volume, that's what the PA is for.

If you need more headroom in general, you can increase the amp's B+ voltage. Typical is 340 to 345, bumping up to around 360 or so what give you a little more headroom.
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Re: 18 Watts and Clean tones

Post by Bieworm »

The classic 18 watt is plenty clean to reasonable level. It annoyed me, so I built a cascade switch to run preamp 2 into preamp 1... just saying
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Re: 18 Watts and Clean tones

Post by ViperDoc »

I like the higher B+ and cascade mod ideas. I just built a Princeton with verb and trem and it sounds awesome if only a bit skinny in the trem dept. I’ve never built a Marshall trem, not sure I’d want it. Thanks for the feedback, even if it’s not negative. Budump ching!
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Re: 18 Watts and Clean tones

Post by ViperDoc »

JMPGuitars wrote:
Sat 09/26/20 3:28 pm
NFB is not what you want, it kills the 18W tone.

There's no reason you shouldn't be able to get enough clean tone from an 18W amp. If you need more volume, that's what the PA is for.

If you need more headroom in general, you can increase the amp's B+ voltage. Typical is 340 to 345, bumping up to around 360 or so what give you a little more headroom.
Thanks. Are you placing the 340-345 straight out of the PT secondary or at the second filter cap node?
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Re: 18 Watts and Clean tones

Post by JMPGuitars »

ViperDoc wrote:
Sat 09/26/20 5:14 pm
Thanks. Are you placing the 340-345 straight out of the PT secondary or at the second filter cap node?
B+ is the converted DC voltage coming from your rectifier to the standby switch to the first filter cap. The second filter cap (typically the second half of a cap can) is not the full B+ voltage.
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Re: 18 Watts and Clean tones

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Right. Thanks!
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Re: 18 Watts and Clean tones

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ViperDoc wrote:
Sat 09/26/20 5:00 pm
I like the higher B+ and cascade mod ideas. I just built a Princeton with verb and trem and it sounds awesome if only a bit skinny in the trem dept. I’ve never built a Marshall trem, not sure I’d want it. Thanks for the feedback, even if it’s not negative. Budump ching!
The 18 watt trem is pretty awesome. I'm very picky on trems and I like the 18 watt trem!!
The best trem IMHO houses in the fender CVR. That one is soooo good that I decided to mod my vibro king's ugly optotrem to that bias vary trem. Most will say that bias vary trem is no good on higher output 6L6 amps because of the bias setting VS trem depth problems... welll BS!!! It works great at any bias setting.
Just saying I am a trem lover 😍😍
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Re: 18 Watts and Clean tones

Post by katopan »

An 18 Watt normal channel gives great sounding clean tones. When I play out it's my ideal amp because it gives clean to edge of distortion at around similar volumes, but a nice volume boost when you turn up for soloing. That's all controlled from the guitar volume knob.

But you need to roll back the guitar rather than set the amp volume knob down at anemic.

It's a harmonic rich clean that sounds great live. But if that doesn't work for you and you're after a different sounding clean tone, then in my mind you're after a different amp rather than mods.
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Re: 18 Watts and Clean tones

Post by ViperDoc »

katopan wrote:
Sun 10/11/20 7:46 pm
An 18 Watt normal channel gives great sounding clean tones. When I play out it's my ideal amp because it gives clean to edge of distortion at around similar volumes, but a nice volume boost when you turn up for soloing. That's all controlled from the guitar volume knob.

But you need to roll back the guitar rather than set the amp volume knob down at anemic.

It's a harmonic rich clean that sounds great live. But if that doesn't work for you and you're after a different sounding clean tone, then in my mind you're after a different amp rather than mods.
Noted. I do like working the guitar volume when I play, it's nice and flexible. I've been shocked by how certain amps don't play along with that. I have a 40-watt Dr. Zed 6V6 Remedy that can't take my guitar volume set below 9, it just dies. I opened it up to study it out and got side-tracked by other projects.

I'm going to work harder on target voltages with my most recent 18W and see how it affects things, particularly with my PI. My amp sounds really good, but I do wonder about how loud I can expect to play clean with a 2xEL84 amp. The two 18-watt Marshall-style amps I've built are the only ones I've ever played, so there's an equal opportunity for accomplishment as there may be for ignorance, I suppose.
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Re: 18 Watts and Clean tones

Post by katopan »

I've gigged my 18 Watt at small bar type venues and it kept up fine clean to overdriven. Of course that's through an efficient speaker. Only when stage volumes got stupid at open blues nights I used to go to was it not enough.
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Re: 18 Watts and Clean tones

Post by colossal »

katopan wrote:
Sun 10/11/20 7:46 pm
An 18 Watt normal channel gives great sounding clean tones. When I play out it's my ideal amp because it gives clean to edge of distortion at around similar volumes, but a nice volume boost when you turn up for soloing. That's all controlled from the guitar volume knob.

But you need to roll back the guitar rather than set the amp volume knob down at anemic.

It's a harmonic rich clean that sounds great live. But if that doesn't work for you and you're after a different sounding clean tone, then in my mind you're after a different amp rather than mods.
Yes, everything about this ^^ They really are fantastic sounding amps and so simple; Volume and Tone (what more do you need?). No knob fiddling. Just set it and forget it. That said, I think whether it works for you depends on your gigging situation and style of music you play. But I find the touch sensitivity, dynamic compression (without being too compressed), and harmonically rich sound is pretty amazing. I think they sound great with a 20W Heritage Greenback or an Alnico Blue.

I have built them with a Normal Channel and cascaded channel and actually prefer the Normal channel. The paralleled triode, single gain stage has a fatness that I keep coming back to. The cascade channel (Zaphod Galactic schematic) is brighter and more cutting. It sounds great, but I really like what the Normal channel does. Also, trying different 12AX7s in both preamp and phase inverter is a good way to change the voice a little.
Bieworm wrote:
Sat 09/26/20 4:26 pm
The classic 18 watt is plenty clean to reasonable level.
I agree. My builds tend to have a fair amount of clean before they start to hit that sweet spot where they thicken up and start to bite when you dig in. It's not a super crispy Fender clean, but a warm, rich clean with a little bit of fur and blur on the edge of the note, without getting in the way. Cathode bias is part of the magic with these amps.
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Re: 18 Watts and Clean tones

Post by ViperDoc »

I agree. My builds tend to have a fair amount of clean before they start to hit that sweet spot where they thicken up and start to bite when you dig in. It's not a super crispy Fender clean, but a warm, rich clean with a little bit of fur and blur on the edge of the note, without getting in the way. Cathode bias is part of the magic with these amps.
That's what I'm after. In looking at other circuits on this site, the EF86 Modern Classic caught my eye. It essentially looks like a "trem lite" amp with an EF86 on the other channel. I understand these pentodes are sensitive. Your thoughts? What I've heard sounds interesting, as far as what I can gather on YouTube.
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Re: 18 Watts and Clean tones

Post by JMPGuitars »

ViperDoc wrote:
Tue 10/13/20 6:39 pm
That's what I'm after. In looking at other circuits on this site, the EF86 Modern Classic caught my eye. It essentially looks like a "trem lite" amp with an EF86 on the other channel. I understand these pentodes are sensitive. Your thoughts? What I've heard sounds interesting, as far as what I can gather on YouTube.
Do you want a tremolo? If so, you should check out the Tremolo TMB. I'm working on recording a demo of mine now, it will be up soon. Bieworm has a good demo of his. The way I designed it, you can get a surprising amount of clean headroom depending on how high output your pickups are (but even still, with higher gain pickups you can roll off the volume slightly).

Regarding EF86, I like them. It's a different flavor, but it's nice. Yes, you need a good quality tube, and build quality will have a huge effect on how good/clean it sounds. I drew the EF86 Modern Classic based on the older style EF86 Lite, but if you want a better overall sound, and more control, I would suggest copying the EF86 channel from the EF86 on my EF86 Xtra docs.

This is a mediocre in-process demo of my Tremolo TMB: https://www.instagram.com/p/CF7i89PHfmr/

This is a mediocre demo of the EF86 Xtra: https://youtu.be/WK7U1Na9sPg

Thanks,
Josh
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Re: 18 Watts and Clean tones

Post by ViperDoc »

Those amps sound great, Josh. The intensity on that tremolo has a nice range. I like the harshness on tap. It’s a lot more stark than my Princeton. How slow can you dial that in?

I’ll tell you, my ideal amp might be a low-gain TMB trem! Like a normal channel with the 3-band tone stack. Onboard trem and verb would not hurt at all. I wonder who has a schematic for something like that...
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Re: 18 Watts and Clean tones

Post by katopan »

My build has a Lite IIb channel and the standard Vox EF86 channel. I love the extra harmonics in the tone of the EF86 channel in an 18 Watt. But there is more gain (unless you change resistor values to knock it down, which is an option) than the normal channel, so it doesn't clean up as well.

My standard set up is to use a passive A/B pedal to switch between channel selections. The Lite IIb channel gets set up for clean to dirty rhythm controlled from the guitar, and the EF86 channel set up for leads. Works great for a good variety of song styles.
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