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Mini JCM800 MV KIT W/MODS
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I am proud to announce the new “Mini” JCM 800 Master Volume High Gain Amp Kit!
This kit is based on the legendary Marshall JCM800 model 2204 from the ‘80’s.
Most Marshalls with that "signature" tone were not stock,
so to get your sound in that “Holy Grail” of tone I have added
a few mods! This kit has great sustain, and tone that really does rock and to top it off it provides it at
bed room levels without any other gadgets, such as tone robbing attenuators or stomp boxes!
The sound is heavy but with some nice clarity, and midrange.
The tone stack has a more usable range than a stock amp.
Note: This amp kit is designed for high gain at low and medium volumes
(med. vol.= pretty loud) at these volumes the amp is stable and sounds
great as described above, at higher volumes 3/4 and up the amp can become unstable.
But usually this is due to a few factors and is just what could happen.
This kit is not for a beginner or amatures and It is not intended for your first time diy amp build.
Electrical skills, knowledge and safety are all needed to build this kit. You build it at your own risk, and according
to your local electrical codes.
Features:
1. Single Channel High Gain
2. 2204 Modded Preamp
3. PPIV MV (drive control)
4. EL84 Power Amp
5. Adjustable Bias
6. Quality Transformers & Choke Made in Canada
7. One chassis styles available, designed for a head but could be fliped for a combo
8. Comes With or Without Tubes
9. Power Switch and GZ34
Sound Samples
This clip was mic directly into my sound card no effects,
volume was on 2, and it was at bed room levels!
The guitar is a LP Deluxe
with a single 12" Hellatone 30 speaker,
all traks recorded with the same amp described above.
 Guitars Gone Wild
Hammer Of the Axe
Southern Sundown
Includes:
A: Blank 16ga Aluminum Chassis Head or Combo if flipped.
C: Resistors and capacitors will vary (metal, Film, or Comp) and Capacitors (Orange Drops, Mallory, or Xicon)
D: .125" Thick Turret Board Double Row Heavy Turrets Colors Vary
E: All “Carling” Switches and “Cliff” Jacks (Brand Names & Quality)
F: Most Mounting Hardware
G: 600V Wire Kit
Note:
(i) At times an individual brand of resistor or Capacitor may need to be
substituted for another type or brand depending on availability and stock.
(ii) Kit comes with everything except a speaker and cabinet
(iii) Delivery time is 1 or 2 weeks depending on volume of sales.
(iv) Hammond power transformer may vary from the one shown.
Introductory Price Offer:
$425.00 No Tubes
$458.00 With Tubes
( including Tube Rectifier )
Does not include shipping
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Combo Back 18watt style
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This chassis is a Fender look but 18watt amps have this type of chassis as well as the lengendary Marshall "blues breaker" combo!
This kit can be built in three types of chassis styles, 18watt style to fit existing 18watt cabs-these are the style shown in the pic
and are usually 20" long x 6" x 2", the one shown in the pic is a bit smaller about 15" x 6" x 2" long. The second type is the head style
also 20" long x 6.5" x 2.125" this chassis size will fit in any head cab out there except a large box. The third chassis is like a eightys
style Marshall combo which is an upside down head chassis.
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Top Side
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This is the begining of a new project that is rolling full steam ahead, its called project Mini JCM!
I am building the first one as a combo and a proto-type, the wattage will be arround 15-20 watts approx.
Built on one of my hand bent chassis that I sell, this is .051" thick aluminum. You do need a reinforcement plate if you use any laydown
transformer as seen but for a small combo chassis its plenty strong enough if you use end caps as all my chassis have.
What it is not to the JCM:
EL84's with a single input and because of the small chassis size, and the Mods I am doing I had to eliminate the middle pot and the presence
pot,
they will still be their in part as a fixed halfway value but built into the board. Also I am and have been cutting a few corners
such as a vintage power transformer 280-0-280, a fender choke that I had laying arround, and a 10 watt audio output transformer.
What it is to the JCM:
Same pre amp haveing 6 preamp stages including the phase inverter, and in the same configuration, same longtailed phase inverter, same
adjustable bias.
Note that a 18watt TMB only has 5 preamp stages including the phase inverter.
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Inside
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Here I have compleated all the wireing that can be done before the board and pots go in.
I have labled some of the wires to make the job a little easier.
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V4 V5 V6
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This is where the Mini JCM is different - having EL84 power tubes, so as you see mounted on the tube sockets above are 100 Ohm screen grid
3 watt resistors instead of the 1k that El34 tubes would use.
Also different are the 1.5k control grid resistors, the EL34's use 5.6k. I will be using adjustable bias to help keep this project true to
its name! I will also be doing my favorite mod to this amp, it won't be stock, but then again most Marshalls are not!
The black resistors are 3watt 1-Ohm 1% and on my layouts are labled R-CB-1&2 for (Resistor-Cathode Bias-1) These resistors are needed
if you are going to use the cathode resistor bias method. This is the easy and fast way to set and check your power tube bias.
Much more to come on this project very soon!
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Cliff Jack
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Here are the Cliff Jack details, this shows the RG-174 sheilded input cable that goes to pin 2 of the first pre amp tube V1. The 1-Meg pull
down resistor and the cloth covered grounding wire, and Thats all their is to it.
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Inside
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Here is the the Mini JCM with its new board in place. This chassis is 16gauge aluminum and is pretty ridgid in part because of a few design
elements such as welded end caps, some thicker cahssis don't have welded end caps, and having end caps provides better shielding. The small
combo size also naturally contributes to making a thiner material ridgid. A transformer reinforcement plate was also used. See my parts page
for my chassis Seen Here custom size chassis available just ask. The next best
step up from 16 gauge is .063" this is a very nice material to work with and punches nice and is strong. You don't need to spend a fourtune
on amp parts, to build a good quality amp!
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HIGH VOLTAGES CAN KILL YOU - ALWAYS WORK SAFE!
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You have to understand how to safely work inside the chassis
of a tube amp. Just reading this is not enough, read all links bellow; here are
a few tips: Never work on a amplifier that is plugged into the
wall socket, always unplug it first! Stand on a rubber mat of
some sort or wood never on concrete and don't work bare foot, under the influence of alcohol
or any other drug, legal or not for that matter. Here is another
good tip: Only probe an amp with you're right hand and with you're
left hand by you're side. So if you do happen to take a high
voltage shock, the the voltage will not go across you're chest!
Wear Protective Rubber gloves!
High Voltage is stored in the electrolitic capacitors and they
need to be discharged! That's what I'm doing in this pic.
These are those large round can's and there usually blue or black.
The discharge tool is made of 600 Volt wire with a 3-5 watt resistor
of 500 to 1000 ohms. Basically you clip one side to ground then clip
the other end to the Pos + side of the capacitor. If I have two cans
as seen here then there are actually 4 capacitors 2 in each can, so I
will take the time and clamp the discharge tool on all 4. Some cans
can have more that 2 as well. Check with you're
multimeter set to 600 DC volt setting and make sure the voltage has
been fully discharged.Please read through these two Links:
How much voltage can kill?
A Must Read!
Electrical Safety 1
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