18w Modern Classic Build

[Atomicmod]

Long time lurker; first time poster here...

I recently stumbled into a Mojotone 18w trem kit, thinking I was getting something else. Yes, I ordered from StewMac. So, imagine my total lack of surprise when this amp turned into a complete ****. Rather than waste anymore time screwing around with the ridiculous Mojotone circuit, I’ve decided to scrap my current Mojotone turret board and start over. I’ll be keeping as many parts as possible from the Mojotone kit, but I’ll need to replace the turret board and the majority of the silly carbon comp resistors that were supplied with the kit.

So, my first question for the distinguished folks at 18watt.com:

Any suggestions as to where I can source a pre-made turret board for an 18W Modern Classic build? I just don’t have the time to make one myself, sadly...

Thanks!

[Atomicmod]

I might just have to build the 5E3 that I have sitting here while I wait for the necessary items to continue with my 18 watt aspirations...

[Bieworm]

You'd better take your time for the build. There are standard predrilled turretboards (7×30 holes) available. The modern classic is just a rearrangement of the classic 18 Watt components, for optimal structural reasons...

And take your time for the rest of the build too. Your result will benefit from it...

If you don't have a turret tool I can teach you how to attach them without it

[JMPGuitars]

Turret tools are not expensive, or hard to find. I have a list of what I use here: viewtopic.php?f=25&t=25173

I use the Keystone TL-8 set, with Keystone 1509-4 turrets.

Thanks,
Josh

[Atomicmod]

I went ahead and ordered a pre-drilled board and 100 turrets. Sadly, I have two never used mojotone boards sitting here. I guess there’s probably no way to use those...

[Daviedawg]

Can I stick my head above the parapet and say that I use carbon comps a lot. I like the look and the tone. They are a bit more work but nothing major. I check the values before fitting them, selecting the closest values. Also in my 18 watt build I swapped out three which were noisy, by a process of elimination. I replaced them with other CCs which were less noisy. My few vintage amps are of course all CCs with no real issues other than where they have been abused.

How much they contribute to tone is a matter of debate.....

And just to add (while ducking) that I dislike building with turrets. I much prefer tag boards and strips. Alterations to work in progress are faster and easier. No under board connections. Mostly I dry assemble without a detailed layout since no board build is needed. I wish I could get tag board like is fitted in my Watkins Scout. It has hook shaped tags rather than closed so you can slip on pre-looped component wires for a great neat connection.

Dd

[JMPGuitars]

Can I stick my head above the parapet and say that I use carbon comps a lot. I like the look and the tone. They are a bit more work but nothing major. I check the values before fitting them, selecting the closest values. Also in my 18 watt build I swapped out three which were noisy, by a process of elimination. I replaced them with other CCs which were less noisy. My few vintage amps are of course all CCs with no real issues other than where they have been abused.

How much they contribute to tone is a matter of debate.....

And just to add (while ducking) that I dislike building with turrets. I much prefer tag boards and strips. Alterations to work in progress are faster and easier. No under board connections. Mostly I dry assemble without a detailed layout since no board build is needed. I wish I could get tag board like is fitted in my Watkins Scout. It has hook shaped tags rather than closed so you can slip on pre-looped component wires for a great neat connection.

Dd

A few points.

1. You're not a novice. An advanced tech (such as yourself) can make a noisy situation better. While you're right that the tone is debatable, the noise factor is not. They're inherently noisier. The most obvious point is the 1M to ground from the input jack - those should always be metal film. I do usually use CC for the PI plates, as the benefit there is scientifically measurable and repeatable.

2. Everybody has a preference. Some like tag boards, some like eyelets, some like turrets. I like turrets. Turrets don't require any under-board connections.

3. To your point about them being easier to make changes to work in progress, I completely disagree. If you're using good mechanical connections before soldering, I find it's no easier than turrets (and likely harder) to make changes. Especially since tag boards are typically more flimsy than turrets. I suppose if I didn't have a desoldering gun, I might agree since it's probably easier to clean the old solder off a tag board solder lug than a turret in that situation.

A complex build like this would have been a nightmare without a well thought out board:

_JMP9078.jpg

Instead it's dead quiet and sounds awesome.

Personally I love how solid my turret boards feel with the FR4/G10 boards and Keystone turrets. But to each their own. Nobody's gonna tell you to stop liking your tag boards if that's what floats your boat.

Thanks,
Josh

[Atomicmod]

I never use under board connections - seems like a bad idea, considering that you could potentially have to de-solder everything just to check any of the under-board connections. I’ve had no issue putting those connections on the top side of the turret board, while making sure to keep my runs oriented at right angles with other connections that they cross...

[JMPGuitars]

I never use under board connections - seems like a bad idea, considering that you could potentially have to de-solder everything just to check any of the under-board connections. I’ve had no issue putting those connections on the top side of the turret board, while making sure to keep my runs oriented at right angles with other connections that they cross...

You can check under-board connections with a multimeter. The bigger issue is if they need to be fixed or modified at all.

[Atomicmod]

That was exactly what I was getting at - making changes becomes a lot more involved in that scenario...

[ViperDoc]

A complex build like this would have been a nightmare without a well thought out board:
_JMP9078.jpg

Instead it's dead quiet and sounds awesome.

Got a thread on that amp build? Looks killer!

[JMPGuitars]

A complex build like this would have been a nightmare without a well thought out board:
_JMP9078.jpg

Instead it's dead quiet and sounds awesome.

Got a thread on that amp build? Looks killer!

Haha, thanks! I have not decided whether or not I will be sharing that circuit. Even if I decide to, I probably won't share the reverb part of the circuit (sorry fellas).

Here's a demo: https://www.youtube.com/watch?v=GZPsdjDZd58

That demo has two versions of that circuit. One is 18W no reverb, the other is 36W with reverb.

Thanks,
Josh

[Daviedawg]

No I definitely would not attempt that without a prepared and checked layout for most of it. Nice job Josh.

Dd

[Bieworm]

yesterday my mod classic started to give light popping sounds. Obviously tube related. Then there was suddenly no sound anymore. The PI tube was a goner. White powder inside the bottle. After replacing that tube and checking voltages everything was crisp and fine again.

1. I hope it was a tube flaw
2. It was a JJ 12AX7 S..
3. I put the same type JJ as a replacement

Now let's wait and see...

[JMPGuitars]

yesterday my mod classic started to give light popping sounds. Obviously tube related. Then there was suddenly no sound anymore. The PI tube was a goner. White powder inside the bottle. After replacing that tube and checking voltages everything was crisp and fine again.

1. I hope it was a tube flaw
2. It was a JJ 12AX7 S..
3. I put the same type JJ as a replacement

Now let's wait and see...

I've been avoiding JJs since I had all those troubles with their EL84s. If the top of the tube turns white instead of silver/grey then that usually means the tube is cracked and lost its vacuum seal.

[Bieworm]

yesterday my mod classic started to give light popping sounds. Obviously tube related. Then there was suddenly no sound anymore. The PI tube was a goner. White powder inside the bottle. After replacing that tube and checking voltages everything was crisp and fine again.

1. I hope it was a tube flaw
2. It was a JJ 12AX7 S..
3. I put the same type JJ as a replacement

Now let's wait and see...

I've been avoiding JJs since I had all those troubles with their EL84s. If the top of the tube turns white instead of silver/grey then that usually means the tube is cracked and lost its vacuum seal.

Interesting.. I always loved the JJ for its mellow sound but the quality is less than it used to be. With sovteks you loose finesse, but they sure are sturdy tubes.. always have been very reliable

[JMPGuitars]

Interesting.. I always loved the JJ for its mellow sound but the quality is less than it used to be. With sovteks you loose finesse, but they sure are sturdy tubes.. always have been very reliable

I usually stick with the new production tung-sol and mullard tubes. They sound better than the JJs ever did, and I've never had issues with them.

[Bieworm]

Interesting.. I always loved the JJ for its mellow sound but the quality is less than it used to be. With sovteks you loose finesse, but they sure are sturdy tubes.. always have been very reliable

I usually stick with the new production tung-sol and mullard tubes. They sound better than the JJs ever did, and I've never had issues with them.

I can vouch for that. My TMB tremolo carries those and I'm really really pleased. Compared the classic to the TMB tremolo again today. For me there is no contest.. the TMB is the fav in every way

[colossal]

I can vouch for that. My TMB tremolo carries those and I'm really really pleased. Compared the classic to the TMB tremolo again today. For me there is no contest.. the TMB is the fav in every way

I like the Tung-Sols as well.

FWIW I run mine also on a higher B+ and I like it. It has more headroom that way. In my band I can hardly get any dirt from my classic 18 watt. It's just not happening yet at that volume.
I play my TMB tremolo at practice. Has dirt in abundance...
But I like having a cleaner amp on the side when necessary

Is it the tone of the TMB Trem that you prefer and/or that there is more gain compared to the dual-triode Normal channel? Better suited to your music, guitars, and playing style? Just wondering...

Also, what output transformer did you use in your Classic and what is your EL84 plate voltage?

[Bieworm]

I can vouch for that. My TMB tremolo carries those and I'm really really pleased. Compared the classic to the TMB tremolo again today. For me there is no contest.. the TMB is the fav in every way

I like the Tung-Sols as well.

FWIW I run mine also on a higher B+ and I like it. It has more headroom that way. In my band I can hardly get any dirt from my classic 18 watt. It's just not happening yet at that volume.
I play my TMB tremolo at practice. Has dirt in abundance...
But I like having a cleaner amp on the side when necessary

Is it the tone of the TMB Trem that you prefer and/or that there is more gain compared to the dual-triode Normal channel? Better suited to your music, guitars, and playing style? Just wondering...

Also, what output transformer did you use in your Classic and what is your EL84 plate voltage?

The tonal difference is more appealing on the TMB... more glassy and cardboard like.. more jimi...more crisp. Maybe it's because I can dial in that mid more..
The TMB is raw and raunchy the classic is mellow and smooth. I like that nasty sound more..
On both I use the hammond 1750PA
Plate voltage modern classic is 345V and on the TMB tremolo 358V