AN Wonderland/JM 100w layout

[Guy77]

Ciao Franco. Looking great! I also used the new values for the reverb/ clean mixer in a recent JM build and I preferred that as well.
I also lowered the cap across the Reverb pot as mentioned in the drawing. More clean headroom now!

Cheers
Guy

[norburybrook]

it was a game changer to me

I'm interested in how you go about putting the FET in your amp as I'd like to do the same as i think it would be a great addition.

How are you going to switch it?


M

[jazzbass]

Hi norburybrook,

I am attaching some photos of the power supply of the FET relay switch, it is a first test.
I am undecided whether to use the Dumble scheme of the FET or whether to insert a board of the XP Xotic Booster in its place.
Do you think I would have a more modern sound than that obtainable with the FET circuit?

a hug

[norburybrook]

Ah so you need to use a relay then, that's what I was wondering. As regards sound, I like the FET boost circuit so I'd go with that , but the AC boost is also a nice pedal . Is it 9v?

the FET has higher voltage and will probably have more headroom I'd say. A lot of 9v boost pedals have voltage doublers to take them to 18v for this reason.

M

[Guy77]

Hi norburybrook,

I am attaching some photos of the power supply of the FET relay switch, it is a first test.
I am undecided whether to use the Dumble scheme of the FET or whether to insert a board of the XP Xotic Booster in its place.
Do you think I would have a more modern sound than that obtainable with the FET circuit?

a hug

Hi if this Booster is the same as the EP Booster than it works really well with the Wonderland amp!. My friend who I built a JM/Wonderland for owns an EP Booster and he called and said it sounded amazing with this amp. I went over and listed to it in person and he was correct.
Just my 2 cents.

Cheers
Guy

[rootz]

Ah so you need to use a relay then, that's what I was wondering. As regards sound, I like the FET boost circuit so I'd go with that , but the AC boost is also a nice pedal . Is it 9v?

the FET has higher voltage and will probably have more headroom I'd say. A lot of 9v boost pedals have voltage doublers to take them to 18v for this reason.

M

This very much depends on how you construct the FET, like you might know. For anyone who does not now what I mean:
The ODS layouts on this forum show a 150k/8k2 voltage divider for the FET supply and a 10k drain resistor with a 8k2 source resistor. This is not centre biasing! The FET already compresses with small input signal.
Now Martin also shows how to get a more centred bias and does that with a 2020k/22k combo IIRC. This means a higher supply voltage and with the right source resistor, you can bias the drain halfway between the supply voltage and ground potential. This gives more gain and more headroom than the other setup I mentioned before.
I use a EP booster on 18V in front of my amps, or in the loop. It sounds great either way. Really a smooth boost and the switches for bass and top end boost make it really versatile. I use it mostly as a clean boost after all other pedals.

Edit: IIRC the 150k/8k2 combo gives a pretty low supply voltage of around 12V with a 2n4416 and a 10k drain and 6k8 to 8k2 source resistor. Martins solution gives a supply voltage of around 16-18V.

[norburybrook]

Rootz

Thanks for the technical explanation, that makes sense. Also it's worth reiterating the use of pedals in the loop and not just delay/reverb but volume pedal, boost, OD pedals all work really well in the loop in a different way than in front of the amp so experiment with it.

M

[martin manning]

Ah so you need to use a relay then, that's what I was wondering. As regards sound, I like the FET boost circuit so I'd go with that , but the AC boost is also a nice pedal . Is it 9v?

the FET has higher voltage and will probably have more headroom I'd say. A lot of 9v boost pedals have voltage doublers to take them to 18v for this reason.

This very much depends on how you construct the FET, like you might know. For anyone who does not now what I mean:
The ODS layouts on this forum show a 150k/8k2 voltage divider for the FET supply and a 10k drain resistor with a 8k2 source resistor. This is not centre biasing! The FET already compresses with small input signal.

The supply voltage and drain resistor value do not completely specify the bias point. You can operate centered or off-center depending on the choice of the source resistor, same as choosing Rk in a triode stage. The revised FET bias document shows three cases: Low supply voltage off-center, producing 16.6% THD, low-voltage centered, producing 5.9% THD, and high voltage centered producing 4.4% THD (all for Vin = 1kHz, 200 mV).

[jazzbass]

[/quote]

Hi if this Booster is the same as the EP Booster than it works really well with the Wonderland amp!. My friend who I built a JM/Wonderland for owns an EP Booster and he called and said it sounded amazing with this amp. I went over and listed to it in person and he was correct.
Just my 2 cents.

Cheers
Guy
[/quote]

Hi Guy,

Thanks for the news you give me, I was about to abandon the idea and insert a normal FET card, everything is simpler.
If I understand correctly your friend plugs the EP Booster into the IN / OUT sockets and is very happy.
I have no idea how it sounds if it is plugged directly into the input as it is for the FET card.
Also, to have a test, I don't know where to look for the schematics of a stabilized 9 volt power supply to power the EP Booster board, do you have any suggestions?
Thanks

A hug
Franco

[Guy77]

Hi if this Booster is the same as the EP Booster than it works really well with the Wonderland amp!. My friend who I built a JM/Wonderland for owns an EP Booster and he called and said it sounded amazing with this amp. I went over and listed to it in person and he was correct.
Just my 2 cents.

Cheers
Guy
[/quote]

Hi Guy,

Thanks for the news you give me, I was about to abandon the idea and insert a normal FET card, everything is simpler.
If I understand correctly your friend plugs the EP Booster into the IN / OUT sockets and is very happy.
I have no idea how it sounds if it is plugged directly into the input as it is for the FET card.
Also, to have a test, I don't know where to look for the schematics of a stabilized 9 volt power supply to power the EP Booster board, do you have any suggestions?
Thanks
A hug
Franco
[/quote]

***********************************************************************************************************
Ciao Franco. Tube town has some 9v power supply kits that may work.
https://www.tube-town.net/ttstore/tt-ki ... y-9-v.html

My friend just plugs the EP Booster in the front of the amp but you could place it in your effects loop (IN/OUT) too.

EDIT: I agree with what rootz just posted after my post. Install the FET and just use the EP Booster Pedal in the loop or in front

Cheers
Guy

[rootz]

Depends on what you want Franco! Just a clean boost for solo's: put an EP (or (buffered) volume pedal) in the loop. Want to boost for a bit of overdrive and/or a boost for solo's? Put it in front. This is what I frequently do for smaller gigs or when I don't want to mess with a Dumbleator and extra cables: pedal board and EP boost for solo's.

But seriously, install that FET board, they are cool and definitely add something unique to the sound. Works great for single coils to fatten the sound a fair bit. And really not that difficult. I mean, you build whole amps!

[jazzbass]

thank you rootz, thank you all,

I decided that the solution will be the classic FET board with relay switch and pedal.

It is the simplest solution to add some overdrive to the Wonderland / JM sound.

Un abbraccio

Franco

[norburybrook]

thank you rootz, thank you all,

I decided that the solution will be the classic FET board with relay switch and pedal.

It is the simplest solution to add some overdrive to the Wonderland / JM sound.

Un abbraccio

Franco

If you want some overdrive then I'd add the 3 way gain structure switch as well . If you have the standard value reverb mixer and the 68/1M divider yo wont get much drive at all.

you can substitute the 68k for a 250k pot and that will give you variable gain. or use the switch from the CRS amp

M

[jazzbass]

Hi to all TAG friends

It takes a good deal of recklessness to start building an amplifier that derives from H. Dumble's designs.
When the last welding is done we realize that it is a huge adventure, many components, many holes in the chassis as in this case because I had not found chassis ready to buy.
But also a lot of welds, enormous attention to details that normally have no standards and are a continuous invention ... made the test to see if there were short circuits this afternoon test with the valves.
Wish me luck.

Franco

[ijedouglas]

Hi Franco,

Exciting!. You may want to check your solder joints at the bottom of the GNFB resistor as well as the top of the V2 plates. The first choke connection on the power board also looks like it could do with a dab more solder