Monarch

[cdwillis]

I know this is an old thread, but I came across it looking for a schematic for the Monarch. I did a quick control F looking for "Jack Orman" and didn't see anyone mentioning that the stage immediately after the tone stack is the AMZ Mini Booster, his adaptation of the old mu amp circuit

Guitar Effects - AMZ Mini-Booster

The Mini-Booster is a dual jfet transistor boost pedal for guitars.

www.muzique.com

 

[Chuck D. Bones]

Mr. Orman didn't invent the mu amp, but he surely did bring it to the attention of the DIY pedal community. I first saw that circuit using JFETs in an electronics magazine in the mid 70's and built a distortion pedal with it. Catalinbread uses them in many of their pedal circuits. EQD put one in the Monarch, which is the basis of the Viceroy.

 

[yazooligan]

Thanks a bunch for posting this and all your other great posts! This helped me get my Tangerine working. I would've been scratching my head forever.

What was the issue for you?

I like the sound of my Tangerine though I built mine stock, and it does have a problem. If the Bass control is pushed up to the max, it starts to gate and sputter, and then then all sound fades away. It takes a bit of tapping on the 2N5457’s to make the sound come back.

 

[Chuck D. Bones]

The first post in this thread explains what was wrong with the original design. Any board built to that design is leakage-biased and that is absolutely not the way to use FETs. By all rights, none of those boards should have worked properly.

 

[yazooligan]

The first post in this thread explains what was wrong with the original design. Any board built to that design is leakage-biased and that is absolutely not the way to use FETs. By all rights, none of those boards should have worked properly.

Yeah I saw that. Maybe my 5457’s are over 2v. No big deal. Time to order a Viceroy board!

 

[Chuck D. Bones]

I think you missed the point. There is no correct Vp with the original circuit because the bias point is indeterminate. The Viceroy fixes that and a couple of other things too.

 

[temol]

My take on Viceroy

 

[steviejr92]

Man @temol you make the coolest enclosures! Awesome build!

 

[Laundryroom David]

My take on Viceroy

View attachment 47362View attachment 47363View attachment 47364

Phenomenal

 

[Erik S]

My take on Viceroy

View attachment 47362View attachment 47363View attachment 47364

That’s super slick. Size looks perfect. Just wide enough to not be cramped with the double foot switches.

I think you said something about 3d printed brake fingers for big radii? Is that big front radius from one of those?

 

[Chuck D. Bones]

Beautiful!

 

[temol]

Thanks!

I think you said something about 3d printed brake fingers for big radii? Is that big front radius from one of those?

I used custom made brake fingers (R 6mm) but not 3d printed ones. Enclosure made with "plastic" fingers (12mm edge radius) here.

 

[Fama]

There is nothing magic about the 2N5457 and since I don't have any, I tried PF5102 and MPF4393. Both work, but the PF5102 has slightly higher gain in this circuit so I went with that one. Other JFETs will also work.

Could you elaborate on what "slightly higher gain" means here, I used MMBF4393LT1G's and switched out R6 (on the PPCB board) to get Q1 biased to around 5V, but the end result is that if I dime level, gain and juice it's a quite low gain overdrive changing to a medium gain overdrive with the juice switch toggled. But I don't think I should need to dime them (and it also sounds horrible if I don't keep them dimed), so I don't think it's working correctly since "slightly higher gain" makes it sound like the difference should be much smaller.

Q4 was a 2N5088 too, but I can switch it out to a 2N5089 if it helps.

 

[Chuck D. Bones]

Measure the drain and source voltages on Q1 & Q2. Do a thorough visual inspection to look for shorts, bad solder joints, incorrect component values, etc.

 

[music6000]

Could you elaborate on what "slightly higher gain" means here, I used MMBF4393LT1G's and switched out R6 (on the PPCB board) to get Q1 biased to around 5V, but the end result is that if I dime level, gain and juice it's a quite low gain overdrive changing to a medium gain overdrive with the juice switch toggled. But I don't think I should need to dime them (and it also sounds horrible if I don't keep them dimed), so I don't think it's working correctly since "slightly higher gain" makes it sound like the difference should be much smaller.

Q4 was a 2N5088 too, but I can switch it out to a 2N5089 if it helps.

Picturea are worth a thousand words!

 

[Fama]

Picturea are worth a thousand words!

I'll get to it after Christmas

 

[Fama]

Measure the drain and source voltages on Q1 & Q2. Do a thorough visual inspection to look for shorts, bad solder joints, incorrect component values, etc.

I posted here https://forum.pedalpcb.com/threads/viceroy-very-low-gain.20176/

But the voltages were 5.37V drain and 1.63V source for Q1, 5.12V and 1.13V for Q2. I can fine tune Q1 a bit lower if that would help. I believe I checked all the components (except for C2) and they should be correct.

 

[Einzeln]

This one seems to have a big reputation. I can't seem to find any demo though. Not on the forum, or on the www.

 

[harmaes]

It’s better to post my question about the transistors here:

Does the Idss of the JFETs matter in this circuit? I have ones in stock like BF244a, BF245a, J113 which all have VP below 2v but Idss from 4mA to > 20mA.
And the HFE for the 2n5089? I have 2n5088 here that have more gain then the 2n5089 I received.

Have you measured them, or are you going by the datasheets? The higher the ratio Idss/Vp, the higher the gain.


Not normal. At any given mfgr, 2N5088 & 2N5089 are manufactured using the same process & then sorted by HFE. What are the measured values and where did you get them?

I measured the JFETs. Which Idss should I target for? J113 have higher Idss so not ideal without changes?

I got the 2n5088/2n5089 from different sources but used them successfully recently in an Electrovibe build. What HFE should I target for?
Their HFE ranges overlap so it’s possible that a 2n5088 has higher HFE up to 900.

The PF5102 can have a vgs(off) from -0,7 to -1,6v and Idss from 4,0 to 20mA. So also quite some range.
I ordered these as well from Retroamplis but haven’t received them so I’m curious how they measure. Just curious which values you target for each position?

 

[harmaes]

@Chuck D. Bones lists 5x PF5102 in this post: https://forum.pedalpcb.com/threads/jfet-shootout.13363/post-149619

I will see which ones I have within that range and try how these work out after I finish the build, will also check the PF5102 when they arrive.
EDIT: checked my JFET document and I don’t have ones that have an Idss between 7 and 10mA. The BF245a can work probably since they have a VP just below 2 and Idss around 5mA. Most 2n5457 have a lower Idss.