18Watt.com

TriodeLuvr wrote: ↑

Tue 03/09/21 2:12 pm

Seriously, I can't ever leave anything alone. What I really want (in one effects chassis) is a pitch-shifting tremolo driven by it's own LFO (low frequency oscillator), and a "standard" amplitude-shifting tremolo driven by a second LFO. I want the ability to control speed of the two independently, or to drive the two shifters simultaneously from one LFO, either in phase or out of phase with each other (selectable). That's not too much to ask, is it?

Also on this subject, if you were going to add standard tremolo to a non-tremolo Marshall using an effects loop, how would you implement it? Would you use a preamp tube as is done inside the Tremolo TMB? Would you consider an opto-coupler or some other method acceptable instead?

Jack

Jack, have you looked at the Magnatone vibrato? I believe the varistors are the tricky part. But I understand there are some workarounds with modern parts

-Dan

I'm always disappointed with tremolo that's not part of the amp. Previous strymon flint owner talking here...

dbharris wrote: ↑

Tue 03/09/21 8:34 pm

Jack, have you looked at the Magnatone vibrato? I believe the varistors are the tricky part. But I understand there are some workarounds with modern parts

-Dan

Dan, I spent a huge amount of time researching that about 10 years ago. I looked at data sheets for dozens and dozens of modern varistors, but couldn't find any that seemed correct. I even bought several types of silicon-carbide varistors from Russia. Based on the curves, some of them should have been close, but the actual measurements were all over the place. I still have 30 or 40 of those lying around somewhere.

In the end, I've decided it will make more sense to forget the varistor concept and develop something using Hammond saturable-core vibrato transformers (similar to the "Warbler"). I already have the transformers, so that's the first thing to try when I get back on this project.

Jack

Bieworm wrote: ↑

Tue 03/09/21 10:49 pm

I'm always disappointed with tremolo that's not part of the amp. Previous strymon flint owner talking here...

I hope that doesn't turn out to be the case here. My initial thought on all this is to build an outboard tube version that's identical to Tremolo TMB or Fender tremolo. This isn't on the front burner right now due to several hi-fi projects that need my attention. It's a serious interest though, and I'll get to it eventually.

Jack

TriodeLuvr wrote: ↑

Wed 03/10/21 4:38 am

dbharris wrote: ↑

Tue 03/09/21 8:34 pm

Jack, have you looked at the Magnatone vibrato? I believe the varistors are the tricky part. But I understand there are some workarounds with modern parts

-Dan

Dan, I spent a huge amount of time researching that about 10 years ago. I looked at data sheets for dozens and dozens of modern varistors, but couldn't find any that seemed correct. I even bought several types of silicon-carbide varistors from Russia. Based on the curves, some of them should have been close, but the actual measurements were all over the place. I still have 30 or 40 of those lying around somewhere.

In the end, I've decided it will make more sense to forget the varistor concept and develop something using Hammond saturable-core vibrato transformers (similar to the "Warbler"). I already have the transformers, so that's the first thing to try when I get back on this project.

Jack

Yeah, I understand. If you still have any interest, this thread may be helpful.

http://ampgarage.com/forum/viewtopic.ph ... &start=105

I think I also have a PDF white paper sort of thing on my hard drive on the Maggie circuit, modern varistors that should work and the solution Martin Manning found. Let me know if you want me to send it to you.

I've thought I may build an active effects loop with built in reverb and Maggie style vibrato at some point. But it's a little beyond my abilities right now.

-Dan

Thanks Dan, PM sent. Regarding the Maggie, I believe the primary difference between their varistor circuit and a simple phase shifter is that the varistors create simultaneous frequency and volume shift. For this reason, I had always planned to include tremolo/vibrato in the same package, along with controls to vary the depth of each. At some point, I think this all begins to sound somewhat like a Leslie, especially if reverb is added to the mix.

Jack

TriodeLuvr wrote: ↑

Wed 03/10/21 12:28 pm

Thanks Dan, PM sent. Regarding the Maggie, I believe the primary difference between their varistor circuit and a simple phase shifter is that the varistors create simultaneous frequency and volume shift. For this reason, I had always planned to include tremolo/vibrato in the same package, along with controls to vary the depth of each. At some point, I think this all begins to sound somewhat like a Leslie, especially if reverb is added to the mix.

Jack

If you do your build, you'll have to give a shot at Jimi's star spangled banner

Well, I played guitar through my Leslie 322 this afternoon for the first time ever. I've never been able to do that because our small practice amp doesn't have an effects loop. The effect is extremely similar to Magnatone clips I've found on the Internet. It's definitely a richer sound than clips of pure phase shifters like the "Warbler." Again, I attribute this to the modulation of both frequency and amplitude simultaneously. The Leslie might even sound a little better than the Magnatone. Copying this effect will be the goal going forward.

FWIW, this model Leslie has a rotating horn, but the bass section is a stationary 12" woofer driven by an emulator. Both internal amps are solid state. It doesn't produce the lush, gutteral effect of a full Leslie (like a 122 attached to a Hammond B3), but it was inexpensive (and it fits in the living room). Also, one of the inputs is a 1/4" jack, so it's easy to switch between the organ and the guitar amp.

Jack

My apologies for taking this thread OT. My bad. I'll start a new thread if there's more to say.

Jack

This 36W Tremolo TMB Reverb sounds amazing. If only I noticed that the front panel treble and bass pots were labeled opposite of how I wired them. Ooops! I need to swap those around, and then record a demo.

Seriously sounds awesome though. I had a loop playing for a little while to break in the speaker, and it sounds killer. I'm really happy with how the circuit / PCB turned out.

On the bright side, for a moment there I was worried I labeled the PCB backwards, but thankfully it's perfect. I only have 40 of them after all.

All fixed now:

For anybody interested, I updated all doc versions for the Tremolo TMB series. I also added docs for 36W versions, and PCB versions.

I changed the values of the mid pot to 25K, and the treble cap to 220pF. To my taste the amp was too bright with my speaker choice, and those changes made it perfect. If you're using a darker speaker, and want the circuit brighter, use the original 50K mid pot, and 500pF treble cap.

Thanks,
Josh

JMPGuitars wrote: ↑

Sat 03/13/21 11:51 am

For anybody interested, I updated all doc versions for the Tremolo TMB series. I also added docs for 36W versions, and PCB versions.

I changed the values of the mid pot to 25K, and the treble cap to 220pF. To my taste the amp was too bright with my speaker choice, and those changes made it perfect. If you're using a darker speaker, and want the circuit brighter, use the original 50K mid pot, and 500pF treble cap.

Thanks,
Josh

I love the 50k pot, and for treble cap I use a 330pf already anyway. I decided that on my 1st tremolo TMB
But that might have to do with being the magic mix for my old G12h30.
My next build will definitely sport the classic lead 80. It sounds tremendous in my other amp and I loved it in my shiva
It's a speaker that's under the radar, but really worth looking into. The mids it projects are awesome. Right now i have it paired with a g12h30 anniversary... that one is great, but compared to the classic lead there is no contest. The CL80 is hands down superior

Bieworm wrote: ↑

Sat 03/13/21 12:20 pm

I love the 50k pot, and for treble cap I use a 330pf already anyway. I decided that on my 1st tremolo TMB
But that might have to do with being the magic mix for my old G12h30.
My next build will definitely sport the classic lead 80. It sounds tremendous in my other amp and I loved it in my shiva
It's a speaker that's under the radar, but really worth looking into. The mids it projects are awesome. Right now i have it paired with a g12h30 anniversary... that one is great, but compared to the classic lead there is no contest. The CL80 is hands down superior

Honestly the pot makes only a little difference (slight boost into the higher range), and 25K is far more commonly available, that's the main reason that got changed. But that's the beauty of everything being flexible to taste. Use what works with your speakers.

Just wondering, has either of you (Josh or Bieworm) ever built a guitar cabinet with a tweeter? Seems like that would provide a big range of additional high end response. Maybe it would make the amp a little less dependent on the tonal quality of the main speaker.

Jack

interesting point Jack! one of my friends used to play pub gigs and he just used a preamp for the guitar into a PA system which had peavey speakers with tweeters,sounded really good!

TriodeLuvr wrote: ↑

Sat 03/13/21 6:34 pm

Just wondering, has either of you (Josh or Bieworm) ever built a guitar cabinet with a tweeter? Seems like that would provide a big range of additional high end response. Maybe it would make the amp a little less dependent on the tonal quality of the main speaker.

Jack

Not me. IME, guitar speakers are usually too bright. If you look at the published tone curves for most speakers, you can see emphasis on high mids and trebles already.

Don't most guitar speakers roll off pretty fast above 4K or 5K? That truncates a lot of harmonics. I was thinking about this because of my experience with the Leslie. That high frequency horn really makes it shimmer. Maybe I'll clip lead something together and give it a try...

Jack

Yes, but that 2K to 5K range can be ear piercing. I suppose it could be an interesting and/or painful experiment.

JMPGuitars wrote: ↑

Sat 03/13/21 9:43 pm

Yes, but that 2K to 5K range can be ear piercing. I suppose it could be an interesting and/or painful experiment.

The concept I'm thinking about is to pull back that upper-mid response with the tone controls, then accentuate the area above it with the tweeter. The tweeter output will of course bleed into the mids, but again, the tone controls should be able to correct for that. It just seems to me that a speaker system like this would allow the amp to really show its stuff. Didn't Mesa Boogie or some other manufacturer make amps like this, a woofer plus a mid/tweeter cone?

Jack