PAL Fx JCM 800 Emulator  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
User avatar
roseblood11
Tube Twister
Information
Posts: 1886
Joined: 23 Aug 2008, 14:21
Has thanked: 366 times
Been thanked: 313 times

Post by roseblood11 »

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.

User avatar
J0K3RX
Degoop Doctor
Information
Posts: 1057
Joined: 29 Jun 2011, 01:25
Location: US Florida
Has thanked: 315 times
Been thanked: 556 times

Post by J0K3RX »

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

User avatar
jimiguitar
Information
Posts: 44
Joined: 15 Jul 2011, 18:54
Has thanked: 4 times

Post by jimiguitar »

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

User avatar
roseblood11
Tube Twister
Information
Posts: 1886
Joined: 23 Aug 2008, 14:21
Has thanked: 366 times
Been thanked: 313 times

Post by roseblood11 »

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

User avatar
roseblood11
Tube Twister
Information
Posts: 1886
Joined: 23 Aug 2008, 14:21
Has thanked: 366 times
Been thanked: 313 times

Post by roseblood11 »

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...

User avatar
toneman
Resistor Ronker
Information
Posts: 343
Joined: 17 Jul 2007, 13:05
my favorite amplifier: anything that works
Completed builds: meatolation, wobolation, ringolation clones, PAiA synths/modulars, dipthonizer clone, MOTM modules, pedal mods and repairs
Location: sacatomatoes, Kali4neeaa
Has thanked: 182 times
Been thanked: 45 times

Post by toneman »

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.
8)

P.S.
http://drtube.com/schematics/marshall/jcm800pr.gif
Tone-to-the-Bone

User avatar
Cub
Cap Cooler
Information
Posts: 458
Joined: 29 Aug 2011, 07:14
Location: The Netherlands
Has thanked: 102 times
Been thanked: 118 times

Post by Cub »

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
I wish I were a chestnut tree, nourished by the sun.
With twigs and leaves and branches and conkers by the ton.

User avatar
Zool
Information
Posts: 1
Joined: 06 Feb 2014, 00:10

Post by Zool »

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.

User avatar
toneman
Resistor Ronker
Information
Posts: 343
Joined: 17 Jul 2007, 13:05
my favorite amplifier: anything that works
Completed builds: meatolation, wobolation, ringolation clones, PAiA synths/modulars, dipthonizer clone, MOTM modules, pedal mods and repairs
Location: sacatomatoes, Kali4neeaa
Has thanked: 182 times
Been thanked: 45 times

Post by toneman »

good links, zool :!:

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

i HAVE seen the Thunderchief schematic @ RunoffGroove :wink:
and the modded schematic with a tonestack.
but have never built any of the jfet overdrives.

Love those J201s :!: :!:
8)
Tone-to-the-Bone

User avatar
bmxguitarsbmx
Cap Cooler
Information
Posts: 510
Joined: 25 Mar 2010, 21:15
Has thanked: 700 times
Been thanked: 216 times

Post by bmxguitarsbmx »

PAL800 CIRCUITBOARD TOP.jpg
pal 800 pcb bottom copper.jpg
JOK3RX seems to be dead on with this one. Check his link posted above. Let me know if you need anything.

User avatar
J0K3RX
Degoop Doctor
Information
Posts: 1057
Joined: 29 Jun 2011, 01:25
Location: US Florida
Has thanked: 315 times
Been thanked: 556 times

Post by J0K3RX »

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

User avatar
roseblood11
Tube Twister
Information
Posts: 1886
Joined: 23 Aug 2008, 14:21
Has thanked: 366 times
Been thanked: 313 times

Post by roseblood11 »

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/ )

User avatar
POTL
Resistor Ronker
Information
Posts: 335
Joined: 26 Sep 2016, 03:11
Has thanked: 58 times
Been thanked: 67 times

Post by POTL »

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)

User avatar
Intripped
Cap Cooler
Information
Posts: 670
Joined: 25 Aug 2009, 01:03
Location: Italy
Has thanked: 985 times
Been thanked: 305 times

Post by Intripped »

Bass reflex?

User avatar
POTL
Resistor Ronker
Information
Posts: 335
Joined: 26 Sep 2016, 03:11
Has thanked: 58 times
Been thanked: 67 times

Post by POTL »

Intripped wrote:Bass reflex?
LOL :slap: :applause:
phase inverter
Google Translate is strange :horsey:

User avatar
Intripped
Cap Cooler
Information
Posts: 670
Joined: 25 Aug 2009, 01:03
Location: Italy
Has thanked: 985 times
Been thanked: 305 times

Post by Intripped »

:)

User avatar
bmxguitarsbmx
Cap Cooler
Information
Posts: 510
Joined: 25 Mar 2010, 21:15
Has thanked: 700 times
Been thanked: 216 times

Post by bmxguitarsbmx »

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

User avatar
Manfred
Tube Twister
Information
Posts: 1936
Joined: 04 Apr 2009, 23:42
Has thanked: 1668 times
Been thanked: 1344 times

Post by Manfred »

I made a PCB-Layout clone according the Shots and traced the circuit.
Some component values are unknown.
PALJCM800_Wiring.jpg
PALJCM800_Wiring.jpg (58.43 KiB) Viewed 22285 times
PAL800JCM_Layout.JPG
PAL_JCM800_Schematic.JPG
PAL_JCM800_PCB_ComponentSide.pdf
(14.9 KiB) Downloaded 579 times
PAL_JCM800_PCB_SolderSide.pdf
(16.18 KiB) Downloaded 575 times
[attachment=0]PAL_JCM800_PCB_SolderSideMirrored.pdf[/attachment
Attachments
PAL_JCM800_PCB_SolderSideMirrored.pdf
(16.49 KiB) Downloaded 480 times

User avatar
POTL
Resistor Ronker
Information
Posts: 335
Joined: 26 Sep 2016, 03:11
Has thanked: 58 times
Been thanked: 67 times

Post by POTL »

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
Image
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

User avatar
J0K3RX
Degoop Doctor
Information
Posts: 1057
Joined: 29 Jun 2011, 01:25
Location: US Florida
Has thanked: 315 times
Been thanked: 556 times

Post by J0K3RX »

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

Most of the values will be the same...

Post Reply