PAL Fx JCM 800 Emulator

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.

PAL Fx JCM 800 Emulator

Postby roseblood11 » 16 Feb 2017, 11:45

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.
https://youtu.be/I1QHo7-9O58
roseblood11
Opamp Operator
 
Posts: 1694
Joined: 23 Aug 2008, 15:21
Has thanked: 324 times
Have thanks: 301 times

Re: PAL Fx JCM 800 Emulator

Postby J0K3RX » 16 Feb 2017, 23:44

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

For this message the author J0K3RX has received thanks:
bmxguitarsbmx (14 Jun 2017, 19:19)
User avatar
J0K3RX
Degoop Doctor
 
Posts: 979
Joined: 29 Jun 2011, 02:25
Location: US Florida
Has thanked: 295 times
Have thanks: 466 times

Pal jcm 800 emulator

Postby jimiguitar » 25 Feb 2017, 16:06

Has any one seen the videos of the pal 800 emulator and their other products
I
jimiguitar
 
Posts: 44
Joined: 15 Jul 2011, 19:54
Has thanked: 4 times
Have thanks: 0 time

Re: Pal jcm 800 emulator

Postby roseblood11 » 25 Feb 2017, 20:34

Yes, it's great. I'd really like to see a schematic.
roseblood11
Opamp Operator
 
Posts: 1694
Joined: 23 Aug 2008, 15:21
Has thanked: 324 times
Have thanks: 301 times

Re: PAL Fx JCM 800 Emulator

Postby roseblood11 » 02 Mar 2017, 00:45

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...
roseblood11
Opamp Operator
 
Posts: 1694
Joined: 23 Aug 2008, 15:21
Has thanked: 324 times
Have thanks: 301 times

Re: Pal jcm 800 emulator

Postby toneman » 03 Mar 2017, 05:44

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.
8)

P.S.
http://drtube.com/schematics/marshall/jcm800pr.gif
Tone-to-the-Bone
User avatar
toneman
Resistor Ronker
 
Posts: 270
Joined: 17 Jul 2007, 14:05
Location: sacatomatoes, Kali4nia
Has thanked: 86 times
Have thanks: 19 times

Re: PAL Fx JCM 800 Emulator

Postby Cub » 03 Mar 2017, 10:14

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
I wish I were a chestnut tree, nourished by the sun.
With twigs and leaves and branches and conkers by the ton.
User avatar
Cub
Resistor Ronker
 
Posts: 279
Joined: 29 Aug 2011, 08:14
Location: The Netherlands
Has thanked: 55 times
Have thanks: 58 times

Re: Pal jcm 800 emulator

Postby Zool » 04 Mar 2017, 00:30

In this video there are some pictures showing the inside of the pedal:
https://youtu.be/I1QHo7-9O58

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.
Zool
 
Posts: 1
Joined: 06 Feb 2014, 01:10
Has thanked: 0 time
Have thanks: 0 time

Re: Pal jcm 800 emulator

Postby toneman » 04 Mar 2017, 01:06

good links, zool :!:

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

i HAVE seen the Thunderchief schematic @ RunoffGroove :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
toneman
Resistor Ronker
 
Posts: 270
Joined: 17 Jul 2007, 14:05
Location: sacatomatoes, Kali4nia
Has thanked: 86 times
Have thanks: 19 times

Re: PAL Fx JCM 800 Emulator

Postby bmxguitarsbmx » 15 Jun 2017, 05:19

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.
You do not have the required permissions to view the files attached to this post.

For this message the author bmxguitarsbmx has received thanks: 2
Manfred (11 Oct 2017, 17:00), modman (20 Jun 2017, 12:05)
bmxguitarsbmx
Breadboard Brother
 
Posts: 117
Joined: 25 Mar 2010, 22:15
Has thanked: 180 times
Have thanks: 62 times

Re: PAL Fx JCM 800 Emulator

Postby J0K3RX » 16 Jun 2017, 19:04

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

For this message the author J0K3RX has received thanks:
bmxguitarsbmx (20 Jun 2017, 20:10)
User avatar
J0K3RX
Degoop Doctor
 
Posts: 979
Joined: 29 Jun 2011, 02:25
Location: US Florida
Has thanked: 295 times
Have thanks: 466 times

Re: PAL Fx JCM 800 Emulator

Postby roseblood11 » 02 Oct 2017, 21:47

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/ )
roseblood11
Opamp Operator
 
Posts: 1694
Joined: 23 Aug 2008, 15:21
Has thanked: 324 times
Have thanks: 301 times

Re: PAL Fx JCM 800 Emulator

Postby POTL » 03 Oct 2017, 03:57

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)
POTL
Solder Soldier
 
Posts: 226
Joined: 26 Sep 2016, 04:11
Has thanked: 47 times
Have thanks: 48 times

Re: PAL Fx JCM 800 Emulator

Postby Intripped » 03 Oct 2017, 04:52

Bass reflex?
Intripped
Cap Cooler
 
Posts: 456
Joined: 25 Aug 2009, 02:03
Has thanked: 519 times
Have thanks: 209 times

Re: PAL Fx JCM 800 Emulator

Postby POTL » 03 Oct 2017, 05:55

Intripped wrote:Bass reflex?

LOL :slap: :applause:
phase inverter
Google Translate is strange :horsey:
POTL
Solder Soldier
 
Posts: 226
Joined: 26 Sep 2016, 04:11
Has thanked: 47 times
Have thanks: 48 times

Re: PAL Fx JCM 800 Emulator

Postby Intripped » 04 Oct 2017, 13:26

:)
Intripped
Cap Cooler
 
Posts: 456
Joined: 25 Aug 2009, 02:03
Has thanked: 519 times
Have thanks: 209 times

Re: PAL Fx JCM 800 Emulator

Postby bmxguitarsbmx » 04 Oct 2017, 21:10

Don't get too excited that this sounds like a jcm800.
bmxguitarsbmx
Breadboard Brother
 
Posts: 117
Joined: 25 Mar 2010, 22:15
Has thanked: 180 times
Have thanks: 62 times

Re: PAL Fx JCM 800 Emulator

Postby Manfred » 11 Oct 2017, 17:08

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

PALJCM800_Wiring.jpg


PAL800JCM_Layout.JPG


PAL_JCM800_Schematic.JPG


PAL_JCM800_PCB_ComponentSide.pdf

PAL_JCM800_PCB_SolderSide.pdf

[attachment=0]PAL_JCM800_PCB_SolderSideMirrored.pdf[/attachment
You do not have the required permissions to view the files attached to this post.

For this message the author Manfred has received thanks: 2
Intripped (12 Oct 2017, 00:05), roseblood11 (12 Oct 2017, 18:07)
Manfred
Cap Cooler
 
Posts: 466
Joined: 05 Apr 2009, 00:42
Has thanked: 771 times
Have thanks: 345 times

Re: PAL Fx JCM 800 Emulator

Postby POTL » 11 Oct 2017, 21:24

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
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
POTL
Solder Soldier
 
Posts: 226
Joined: 26 Sep 2016, 04:11
Has thanked: 47 times
Have thanks: 48 times

Re: PAL Fx JCM 800 Emulator

Postby J0K3RX » 12 Oct 2017, 17:34

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

Most of the values will be the same...

For this message the author J0K3RX has received thanks: 2
bmxguitarsbmx (12 Oct 2017, 18:14), Manfred (12 Oct 2017, 19:17)
User avatar
J0K3RX
Degoop Doctor
 
Posts: 979
Joined: 29 Jun 2011, 02:25
Location: US Florida
Has thanked: 295 times
Have thanks: 466 times

Next

Return to Modern Stompbox Effects (1975 - ...)

Who is online

Users browsing this forum: rcustoms and 17 guests