PAL Fx JCM 800 Emulator

roseblood11 · Post by **roseblood11** » 16 Feb 2017, 10:45

Great pedal... Looks a bit like a runoffgroove design.
Any info about this one?
The picture in the video might be good enough for tracing.

J0K3RX · Post by **J0K3RX** » 16 Feb 2017, 22:44

Looks like the standard JFET JCM800 direct copy of the tube amp values with maybe a few resistor value changes and a couple other mods..

probably not far off from this..
http://www.uk-electronic.de/Download/Be ... JCM800.pdf

jimiguitar · Post by **jimiguitar** » 25 Feb 2017, 15:06

Has any one seen the videos of the pal 800 emulator and their other products
I

roseblood11 · Post by **roseblood11** » 25 Feb 2017, 19:34

Yes, it's great. I'd really like to see a schematic.

roseblood11 · Post by **roseblood11** » 01 Mar 2017, 23:45

yupp, might be close. But I'd really like to know the details. I built many Marshall emulators, and they all were good, but this one might be even closer to the real amps sound.
Butt off course it's quite easy to get that kind of sound with a vintage Les Paul and an Orange Stack...

toneman · Post by **toneman** » 03 Mar 2017, 04:44

gut shots first.......
from effectsdatabase:
http://www.effectsdatabase.com/model/pal/800

"This pedal 100% handmade uses the same circuit schematic that you will find on a JCM800 amp
using especially selected transistors instead of vacuum tubes."
Hmmmm....maybe a little bit of "mojo"??

if the pcb does not use surface mount parts it should be cloneable.

P.S.
http://drtube.com/schematics/marshall/jcm800pr.gif

Cub · Post by **Cub** » 03 Mar 2017, 09:14

I don't think the Pal is a million miles away from the three in the links below and though it sounds really good, I'd say that the 9V JFET amp-emulators has been surpassed by other types of technology.
Guitar FX Layouts: Marshall JCM800 Emulation
JCM 800 Emulator pedal build
JCM800 Emulator vero - Sabrotone

Our brother KMG, for example. He used LND150 MOSFETs at the original "plate" voltage and in the clips he posted, I couldn't tell the difference between the solid state and the tube version !
Fet version of the JCM800

Even at runoffgroove, they have moved on from JFET only and are implementing clipping diodes with great results.
Thunderbird - Plexi Super Lead
Azabache - Vintage Fenders
Britannia - VOX AC-30 Top Boost

Zool · Post by **Zool** » 03 Mar 2017, 23:30

In this video there are some pictures showing the inside of the pedal:

Also here is this JCM800 emulation from years ago:
http://tagboardeffects.blogspot.hu/2014 ... ation.html

I am not good at electronics, just building pedals from layouts, but they look close to me. Both of them has the same number and type of capacitors, resistors, trimmers, potentiometers. I am not good at decoding the resistor color codes in the video (would take me an awful lot of time to do it), and I'm on mobile right now and cant read the capacitor values, but I think it's worth a check.

toneman · Post by **toneman** » 04 Mar 2017, 00:06

good links, zool

had not seen them b4 and they didnt come up in my previous search.

i HAVE seen the Thunderchief schematic @ RunoffGroove

and the modded schematic with a tonestack.
but have never built any of the jfet overdrives.

Love those J201s

bmxguitarsbmx · Post by **bmxguitarsbmx** » 15 Jun 2017, 04:19

JOK3RX seems to be dead on with this one. Check his link posted above. Let me know if you need anything.

J0K3RX · Post by **J0K3RX** » 16 Jun 2017, 18:04

Nice one bmxguitars... I guess this one can be added to the "modern sb traced" catagory now.

roseblood11 · Post by **roseblood11** » 02 Oct 2017, 20:47

So, it's very close to the JCM800 emu, but not 100% exact - at least, the PAL has one more trim pot for master tone.

What I don't like about all variations of this circuit, is the size. Shouldn't it be possible to squeeze it into a 1590B?
It would be really great if somebody could make (and sell) a small pcb with board-mounted pots, maybe double-sided?
Madbean, Aion, 1776???

(I know how to draw veroboard layouts, but not experienced with pcb at all)

My plan is to to squeeze this circuit and a VFE Pale Horse into a 1590BB (horizontal...), or maybe into a 1590Q with a variable relay bypass, like I did with a Crunch Box and an Ibanez ST-9 (both on pcb's from Aion Electronics) here:
http://musikding.rocks/wbb/index.php/At ... rive1-JPG/
http://musikding.rocks/wbb/index.php/At ... rive2-JPG/
(This is the relay bypass board: http://musikding.rocks/wbb/index.php/At ... -Flex-gif/ )

POTL · Post by **POTL** » 03 Oct 2017, 02:57

as far as I understand this is almost 100% preamp scheme + bass reflex, except that in the pedal there is an additional tone adjustment.
Hmm maybe it's worth trying again to assemble this circuit with a bass reflex.
In other things, all my experiments suggest that simply copying the circuit with the replacement of tubes with fets is not the best idea in terms of sound.
At 9 volts it sounds compressed and crumpled, at 18 more interesting, but it's still better to rework the circuit)

Intripped · Post by **Intripped** » 03 Oct 2017, 03:52

Bass reflex?

POTL · Post by **POTL** » 03 Oct 2017, 04:55

Intripped wrote:Bass reflex?

LOL

phase inverter
Google Translate is strange

Intripped · Post by **Intripped** » 04 Oct 2017, 12:26

bmxguitarsbmx · Post by **bmxguitarsbmx** » 04 Oct 2017, 20:10

Don't get too excited that this sounds like a jcm800.

Manfred · Post by **Manfred** » 11 Oct 2017, 16:08

I made a PCB-Layout clone according the Shots and traced the circuit.
Some component values are unknown.

: PALJCM800_Wiring.jpg (58.43 KiB) Viewed 24377 times

PAL_JCM800_PCB_ComponentSide.pdf: (14.9 KiB) Downloaded 617 times

PAL_JCM800_PCB_SolderSide.pdf: (16.18 KiB) Downloaded 628 times

[attachment=0]PAL_JCM800_PCB_SolderSideMirrored.pdf[/attachment

POTL · Post by **POTL** » 11 Oct 2017, 20:24

Okay start Trimming resistors in the range 50k-100k
Gain A1M
Bass A1M
Treble B250K
Middle B25K
Volume A100K
The presence of B100K (possibly B1M)
I collected such schemes, I can tell right away, a good sound will be at 18V
In general, I did not like the sound, there is no power and Mojo

diode 1n4001
Capacitor 100uf or more
I recommend to install in parallel with him 100n ceramics

In general, a complete copy of the scheme is not the best option, we need different modifications to get a better sound, each manufacturer has their own.
For copying do not see the point

J0K3RX · Post by **J0K3RX** » 12 Oct 2017, 16:34

Look here > http://www.uk-electronic.de/Download/Be ... JCM800.pdf

Most of the values will be the same...

PAL Fx JCM 800 Emulator [schematic]