Wonderland/JM100 build

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martin manning
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Re: Wonderland/JM100 build

Post by martin manning »

Those resistors are color coded in an unusual way. They appear to have 6 bands, but the last is clearly gold, and that's odd. If I assume the last two are some form of tolerance and temp coefficient, the one does look like 6k8 or 68k. The other is hard to read, but the multiplier band almost has to be yellow, as it's certainly not orange or red. That makes that resistor 1.15 or 1.18M. The bottom line is how does it sound, including the wet/dry balance. I think I would substitute a pot in for the voltage divider (and that's all it is, a fixed pot... Google it and you will find lots of explanations) and play with it. I would also try a couple of different values for the pot, maybe going as low as 100k to get the loading effect.

Guys who are in the business of designing, repairing, or teaching about guitar amps are not going to give away their knowledge, as that obviously threatens their livelihood. No surprise there. The DIY community has been a great resource for many, but once they have made the jump from amateur to professional it becomes a threat, and their contributions to the public knowledge base will stop, especially if it hits close to their particular niche.
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M Fowler
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Re: Wonderland/JM100 build

Post by M Fowler »

I built my JM Sig Reverb a while ago based entirely on the first schematic posted and it used 68k/1M which I never changed.

I was offered data on changing values but never did because I was so happy with what I had.

The amp was sold soon after being built and that guy built a Dumble 212 loaded with WGS ET-65 speakers using the TAG cab plans posted by good members.

So I really think something else is going on here.

Mark
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norburybrook
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Re: Wonderland/JM100 build

Post by norburybrook »

martin,
That's exactly what was in the back of my mind regarding the FB group.

I agree it's not easy to make out what the values are and Jelle did suggest putting a 250 or 500k pot in there.

Mark, the amp sounds lovely and I just have to accept it's not a loud amp. I realise comparing it to my marshall based dumble blues master isn't a good idea as the BM pre amp/PI is driving the output section fully. In the JM build that 68k acts like a master volume on 2 so the power section isn't getting anything near the gain the BM had, and the way the master is a FX return level control doesn't help, you really do need to have it up pretty much full.

here's an ironic end to this; last night as I was still playing around with the amp I'd left my studio door open and my partner came in and said it sounded like someone sound checking for woodstock out I the street it was so loud :D

volume perception.......

I'm starting on making a cabinet today...this thread isn't over yet....


marcus
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JazzGuitarGimp
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Re: Wonderland/JM100 build

Post by JazzGuitarGimp »

norburybrook wrote: Sat Apr 22, 2017 2:03 pm I'm starting on making a cabinet today...this thread isn't over yet....
I've been closely following this thread; glad to hear it's not over. :-) Looking forward to seeing progress on the woodwork....
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M Fowler
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Re: Wonderland/JM100 build

Post by M Fowler »

I think you have it right there perceived loudness because it doesn't have that biting Marshall tone it has a subtle lower range tone with great reverb.

According to your partner the amp is a keeper :D

Have fun, enjoy that amp through a 212 Dumble style cab with EVM12L or WGS equivalent.
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martin manning
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Re: Wonderland/JM100 build

Post by martin manning »

martin manning wrote: Sat Apr 22, 2017 12:40 pm ...the one does look like 6k8 or 68k. The other is hard to read, but the multiplier band almost has to be yellow, as it's certainly not orange or red. That makes that resistor 1.15 or 1.18M.
But I suppose it could be orange, sometimes the tint varies quite a bit. If so, 115k or 118k and 6k8. That is more like the other stage where the grid load is 100k. That would cut a little of the bottom end too, though.
markusw
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Re: Wonderland/JM100 build

Post by markusw »

martin manning wrote: Sun Apr 23, 2017 2:48 am
martin manning wrote: Sat Apr 22, 2017 12:40 pm ...the one does look like 6k8 or 68k. The other is hard to read, but the multiplier band almost has to be yellow, as it's certainly not orange or red. That makes that resistor 1.15 or 1.18M.
But I suppose it could be orange, sometimes the tint varies quite a bit. If so, 115k or 118k and 6k8. That is more like the other stage where the grid load is 100k. That would cut a little of the bottom end too, though.
I have the impression that there are some 5 band and some 6 band resistors on the board.
e.g. the 100k plate resistors in the reverb section and the mixer seem to have a 3 band code: brown/black/yellow (+red and gold);
Might it be that the "1.15 or 1.18M" is just 3 band brown/black/green = 1.0M?
If 1M is correct, the "6k8 or 68k" should be 68k (or maybe 680k if the multiplier band is orange?) since a 6k8 would reduce the signal too much.
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Re: Wonderland/JM100 build

Post by Bombacaototal »

I just did a bit of catch up on this thread

Below a couple different gut shots of the Mayer amp to help on the 68k discussion

I see blue/?/black/brown/red/gold
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norburybrook
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Re: Wonderland/JM100 build

Post by norburybrook »

thanks Bombacoatotal, (have you got a real name? )

they're pics I posted of the FB page that no one could agree on.

I've PM'd taylor as he builds these amps commercially but not heard back, he's hopefully busy building, as he will know as he had the map in his possession.

Here's his build which definitely has a 1M-68k
wonderland 3.jpg

interestingly this amp is based on the custom reverb and this amp has a gain structure switch:

Gain Structure: The 3 position gain structure switch changes the sensitivity and overall feel of the preamp.  In the down position, the amp feels similar to a vintage blackface, the middle position is much like the Two-Rock Matt Schofield Signature front end with a hotter input stage, and the full up position is our traditional Two-Rock frontend.


do you think that would be before the voltage divider or perhaps it may bypass it or have different values?


also if the JM amp was a prototype maybe those values weren't on the finished model.

Taylor's 50w has a 100k in there if I'm right.
50w wonderlans.jpg

Marcus
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Last edited by norburybrook on Sun Apr 23, 2017 9:05 am, edited 1 time in total.
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martin manning
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Re: Wonderland/JM100 build

Post by martin manning »

markusw wrote: Sun Apr 23, 2017 6:39 amIf 1M is correct, the "6k8 or 68k" should be 68k (or maybe 680k if the multiplier band is orange?) since a 6k8 would reduce the signal too much.
The possible orange I'm referring to is on the larger value resistor. I'm leaning toward a 1.15M or 1.18M and 68k combination.
Last edited by martin manning on Sun Apr 23, 2017 10:45 am, edited 1 time in total.
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martin manning
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Re: Wonderland/JM100 build

Post by martin manning »

norburybrook wrote: Sun Apr 23, 2017 9:00 amthe plot also thickens looking at some pics more closely of one of taylors 50w versions. what do you think the values are here?
1M and 100k
Bombacaototal
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Re: Wonderland/JM100 build

Post by Bombacaototal »

norburybrook wrote: Sun Apr 23, 2017 9:00 am thanks Bombacoatotal, (have you got a real name? )

they're pics I posted of the FB page that no one could agree on.

I've PM'd taylor as he builds these amps commercially but not heard back, he's hopefully busy building, as he will know as he had the map in his possession.

Here's his build which definitely has a 1M-68k

wonderland 3.jpg


interestingly this amp is based on the custom reverb and this amp has a gain structure switch:

Gain Structure: The 3 position gain structure switch changes the sensitivity and overall feel of the preamp.  In the down position, the amp feels similar to a vintage blackface, the middle position is much like the Two-Rock Matt Schofield Signature front end with a hotter input stage, and the full up position is our traditional Two-Rock frontend.


do you think that would be before the voltage divider or perhaps it may bypass it or have different values?


also if the JM amp was a prototype maybe those values weren't on the finished model.

Taylor's 50w has a 100k in there if I'm right.

50w wonderlans.jpg


Marcus
Rafael is my name :)

The Schofield is fairly different from the Mayer. It has 2 tube rectifiers and a Fender like reverb (which you can tell by the tube layout)

And here a gutshot http://ampgarage.com/forum/viewtopic.php?f=4&t=30074
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ToneMerc
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Re: Wonderland/JM100 build

Post by ToneMerc »

norburybrook wrote: Sun Apr 23, 2017 9:00 am

Taylor's 50w has a 100k in there if I'm right.




Marcus
Taylor and I have talked about this amp a fair amount. He does make a change with the 50 and 22 watters, substituting a 100K to ground instead of the 68K.

TM
markusw
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Re: Wonderland/JM100 build

Post by markusw »

martin manning wrote: Sun Apr 23, 2017 9:02 am
markusw wrote: Sun Apr 23, 2017 6:39 amIf 1M is correct, the "6k8 or 68k" should be 68k (or maybe 680k if the multiplier band is orange?) since a 6k8 would reduce the signal too much.
The possible orange I'm referring to is on the larger value resistor. I'm leaning toward a 1.15M or 1.18M and 68k combination.
Don't you think it's possible that the "1.15M or 1.18M" has only a three band code like the 100k resistors?
Aaron
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Re: Wonderland/JM100 build

Post by Aaron »

Here's a pic of Mike's amp. Resistor is 68k. Ceriatone use the 1M-68k.
Image
This is the prototype.
Image
The resistor colours look like blue-grey-black-orange-red-gold. Which according to the 6 band colour code would be 680k, 2% tolerance with 100ppm temp. coefficient.

When I traced it I thought 680k would be too high so assumed it was 68k. We all know where Ceriatone get "their R & D" from, so they probably went from this schematic.

If you look at the 2nd Gen Overdrive Reverbs, they use the resistor/trim pot. 270k to ground-2M2 trimpot w/47k tail.

Aaron
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