18W tremolo PPIMV details

[zaphod_phil]

What is your opinion of my MV lay-out? Is the last layout going to work?

Bieworm, there are plenty of posts on this general topic already. Since the classic Marshall18W gets nearly all of its distortion from the power stage, a post-PI MV is going to be pretty ineffective in any case. It will basically just clean up the tone as you turn down the MV. You really need an amp that has a lot more distortion in the preamp, and use a post-preamp MV instead - ie you would want to build an 18W TMB instead. Otherwise, a VVR or an attenuator between the amp output and speaker(s) are your best options.

[JMPGuitars]

JMP, you already know what I think about putting reverb into Marshall 18W type amps! I call it desecration.

Lol! I know all too well, my friend.

I still like it though, but I agree, it isn't needed.

[Bieworm]

What is your opinion of my MV lay-out? Is the last layout going to work?

Bieworm, there are plenty of posts on this general topic already. Since the classic Marshall18W gets nearly all of its distortion from the power stage, a post-PI MV is going to be pretty ineffective in any case. It will basically just clean up the tone as you turn down the MV. You really need an amp that has a lot more distortion in the preamp, and use a post-preamp MV instead - ie you would want to build an 18W TMB instead. Otherwise, a VVR or an attenuator between the amp output and speaker(s) are your best options.

Maybe I will be very disappointed;)
I can dime the MV anyway and get the powertube overdrive.
It may sound funny, but I'm not really after the distortion.. just a little beef and crunch. I play clean on the verge of breakup mostly. I hope to reach that with the 18W . The MV is probably just for homeplay
It will probably be just fine without the MV.. won't be using it a lot. I'm used to a VK, so volumewise it'll crunch at the volume I am used to play anyway.
The build is nearly finished I'm afraid. With the MV already in position. Just have to hook up the preamptubes and I am gonna light it up. Any warnings before startup except checking all the wiring? Going to do a voltage check first ofcourse

[geoff 1965]

yeah try it,it might suit you but that's why i mentioned earlier about the dual 500K being more suited to amps with preamp overdrive. ZP is right and it actually is more a post inverter drive than volume.you can easily swap to the 1 meg dual & grid leaks if you don't like the 500K, you get more breakup at lower volume with that version.
good luck

[Bieworm]

yeah try it,it might suit you but that's why i mentioned earlier about the dual 500K being more suited to amps with preamp overdrive. ZP is right and it actually is more a post inverter drive than volume.you can easily swap to the 1 meg dual & grid leaks if you don't like the 500K, you get more breakup at lower volume with that version.
good luck

You're right...you did say that.
I will see . if i don't like it I can always adapt to 1M dual pot. The wiring is there already

[Bieworm]

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Ok the amp Works!
I ditched the MV though. It was kinda noisy + the amp isn't THAT loud. My other amps are obviously louder. I think this18W is a good wattage for the majority of playing situations.
The normal channel is definitly what they say about it. It's huge marshall drive and just about right in every aspect!!!
I notice that I will have to learn how to use the amp...but it has got great potential. This is my first marshall type amp. And I play 32 years now. Shame on me!!
Now I will tidy up the working gear and start the making of the combo to put the amp in.
Cheers!!!!

[Bieworm]

20200215_164059.jpg20200215_164110.jpgOk the amp Works!
I ditched the MV though. It was kinda noisy + the amp isn't THAT loud. My other amps are obviously louder. I think this18W is a good wattage for the majority of playing situations.
The normal channel is definitly what they say about it. It's huge marshall drive and just about right in every aspect!!!
I notice that I will have to learn how to use the amp...but it has got great potential. This is my first marshall type amp. And I play 32 years now. Shame on me!!
Now I will tidy up the working gear and start the making of the combo to put the amp in.
Cheers!!!!

Will be using this speaker:

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[JMPGuitars]

Ok the amp Works!

Take some voltages and post them using the chart in the download section. I'd be surprised if your tubes are biased correctly with a 120R cathode resistor.

You also need to be more careful soldering. I can see melted spots on capacitors where the soldering iron touched them. WIMAs are pretty tough, but there's a good chance they go out of spec or defective when that happens.

Thanks,
Josh

[Bieworm]

Ok the amp Works!

Take some voltages and post them using the chart in the download section. I'd be surprised if your tubes are biased correctly with a 120R cathode resistor.


You also need to be more careful soldering. I can see melted spots on capacitors where the soldering iron touched them. WIMAs are pretty tough, but there's a good chance they go out of spec or defective when that happens.

Thanks,
Josh

That 120R came with the kit I ordered. Should I add 10R in series? The ceriatone lay-out suggests 130R...

The wima .01 cap is fine. Is slightly touched in an earlier build. But the trem works just fine. Thnx anyway. Was going to order sozo's to replace the wimas anyway. But hey, I ordered a TMB( tremolo wasn't available) and built the tremolo 18W. the face plate is to be replaced some other time. Nog the trem speed is MID and intensity is BASS.

15818748542827615792295479442471.jpg

[Bieworm]

Ok the amp Works!

Take some voltages and post them using the chart in the download section. I'd be surprised if your tubes are biased correctly with a 120R cathode resistor.


You also need to be more careful soldering. I can see melted spots on capacitors where the soldering iron touched them. WIMAs are pretty tough, but there's a good chance they go out of spec or defective when that happens.

Thanks,
Josh

That 120R came with the kit I ordered. Should I add 10R in series? The ceriatone lay-out suggests 130R...

The wima .01 cap is fine. Is slightly touched in an earlier build. But the trem works just fine. Thnx anyway. Was going to order sozo's to replace the wimas anyway. But hey, I ordered a TMB( tremolo wasn't available) and built the tremolo 18W. the face plate is to be replaced some other time. Nog the trem speed is MID and intensity is BASS. 15818748542827615792295479442471.jpg

the voltages on pin 2 and 7 on the PI tube are off : 32V instead of 50V ...how can I alter that?

[JMPGuitars]

the voltages on pin 2 and 7 on the PI tube are off : 32V instead of 50V ...how can I alter that?

Check the schematic and verify the values and connections of everything around the PI.

Here's the correct voltage chart you should be using: files/JMPGuitars_18_Watt_Classic_Voltage_Test_Chart.pdf

Thanks,
Josh

[Bieworm]

15818787655945983238855974667501.jpg

the voltages on pin 2 and 7 on the PI tube are off : 32V instead of 50V ...how can I alter that?

Check the schematic and verify the values and connections of everything around the PI.

Here's the correct voltage chart you should be using: files/JMPGuitars_18_Watt_Classic_Voltage_Test_Chart.pdf

Thanks,
Josh

Looks like the transformer doesn't deliver 2x3.15V ..I measure 2x2.7V
The components in the PI circuit are within specs. I checked. I don't know , but 15% less current on the filaments seems like a probable cause to the low measurement on the grids...or am I wrong?
The platevoltages on V3 are also off... pin 1 = 184V and pin 6 = 130V... Any ideas?
The cathodes measure 1.43V at pin 3 and 8. This is nearly 50% too much.
FWIW the amp sounds amazing nevertheless. Plugged in at 4Ohms into the 3x10 VK cab (2.66Ohms)

Important notice:
1. since I only have a Hi input on the trem channel, I only put a single 22K resistor between the input and pin 7 on V3 (that should be about right, no?..I copied it from the TMB schematic)
2. my intensity pot is 5K instead of the 1K on the layout... the reason is that I do not have a 1K available..

[Bieworm]

Ok the PI pin 2 and 7 I got from 32V to 49V. Reflowed some connections.
But V3 is still off in the same manner. Could it be the 47uf/40v electrolythic cap from V3 pin 8 to ground? That's an older one that I had laying around. I do have a brand new 47uf 450V . Could that do any harm? On the contrary I think. But I only want to replace that one if you think tis could be related to the voltage problem..

[zaphod_phil]

What is your opinion of my MV lay-out? Is the last layout going to work?

BW, a post-PI MV is practically useless in a classic 18W type amp, as almost all the distortion comes from the power amp stage. All it will do is to clean up the sound. A VVR or attenuator box will be much more effective. I have a feeling I already said that sometime not long ago, or am I imagining it?

[Bieworm]

What is your opinion of my MV lay-out? Is the last layout going to work?

BW, a post-PI MV is practically useless in a classic 18W type amp, where almost all the distortion comes from the power amp. All it will do is to clean up the sound. A VVR or attenuator box will be much more effective. I have a feeling I already said that sometime not long ago, or am I imagining it?

Probably
But did that anyway. All it adds is useless extra noise. I am thinking about the VVR "IF " I would want a MV. But hey...isn't the kick you get from cranking an 18W in the moving of air at higher volume?
I think I'm gonna add an attenuation with high wattage resistors at the output, switchable between full-on and 1/4th power (late night home jamming) ... it's cheap and easy
My fear of a VVR is that it won't give the effect you would want. Maybe after doing all the effort finding out that all I experience is a generic marshallesque tone that has more in common with a cheap stupid line6 .
I'm leaving the circuit alone..it's near perfect right now. And I fell oh so in love with it.
Admitting I put a reverb in front of it...
A Mad Professor Silver Spring... very nice on EVERY setting. Had all the big ones in the past ( flint, topanga, boss 63 fender, ...) reverb..and this one is the absolute best!! Really useful and nowhere near digital sounding. Phil, I need reverb in my sound..I play a lot of morricone, surf,...
Check my band https://vi.be/platform/lonestarbordello

[Bieworm]

Porn alert:

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[JMPGuitars]

Yikes, too many F-bombs for my taste.

[Bieworm]

Yikes, too many F-bombs for my taste.

Josh, you can 't dislike brownface voiced amps. Agreed on blackface amps, but tweeds and brownfaces... those are really badass!!! I have yet to hear an amp that sounds better than the VK. I changed the optotrem to bias vary...that is WOW!

[JMPGuitars]

Josh, you can 't dislike brownface voiced amps. Agreed on blackface amps, but tweeds and brownfaces... those are really badass!!! I have yet to hear an amp that sounds better than the VK. I changed the optotrem to bias vary...that is WOW!

I don't like ANY of their amps from any genre. There are some I dislike more than others though. I prefer G&L guitars over any FMIC any day. To each their own, right?

[Bieworm]

Josh, you can 't dislike brownface voiced amps. Agreed on blackface amps, but tweeds and brownfaces... those are really badass!!! I have yet to hear an amp that sounds better than the VK. I changed the optotrem to bias vary...that is WOW!

I don't like ANY of their amps from any genre. There are some I dislike more than others though. I prefer G&L guitars over any FMIC any day. To each their own, right?

Right!!! And thank God for that
Well.. the red jag is an original 1962. The blonde strat is a squier protone, the red strat is my first new guitar, a 1989 mim. The black jm, the silver jag and the mustang I have built myself. So no real fenders here, except the 62 jag.