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Author Topic: Want to build a peavey bandit 112 redline or Randall RX120D  (Read 25954 times)

kin0

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Want to build a peavey bandit 112 redline or Randall RX120D
« on: November 03, 2010, 11:16:12 AM »
Hay, I want to build a peavey bandit 112 redline or a Randall RX120D
I build a couple of stompboxes but never an amp. I am looking for the PCB and the schematic but can't find one (for both). If anybody can help with the schematic and the pcb and also give some instructions I'll be very greatful.


Oh and for the randall a 60-80 watt ver will be good too.
« Last Edit: November 03, 2010, 02:53:04 PM by kin0 »

Enzo

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #1 on: November 03, 2010, 05:08:41 PM »
You can get the schematic and layout for any Peavey product from customer service at the factory.

You can ask the PV parts folks if they still have boards for that model, but it won;t be an empty board if you plan to build your own.

J M Fahey

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #2 on: November 03, 2010, 06:11:48 PM »
Hi Kin.
You will find *many* schematics, a few layouts and *no* boards available.
The first is usually provided as a service to repair technicians, in case of trouble, but the last would be akin to shooting their own foot, commercially speaking.
Google "Rod Elliott", he kindly provides many schematics, including a guitar preamp and many power amps.
He sells the boards for most of them.
You might get a dead or sick Bandit for peanuts (there are millions of them everywhere) and repair/rebuild it.

kin0

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #3 on: November 04, 2010, 10:38:33 AM »
It's a problem for me to get a broken Bandit cause I don't leave in the US. Also I am not sure I would be able to design such big pcb (I mean not small as a stompbox). Also what about the  randall cause I like it's sound better.

I found some schematics and pcb but I am not sure if it is the preamp or the whole amp.


http://www.about-guitar-amps.com/guitar_amps_schematics/Peavey/Peavey_Bandit_112-2.pdf

Also how can I erase the parts from the pcb so I can use it

(the username is:amp and the pass schematics)
« Last Edit: November 04, 2010, 04:00:22 PM by kin0 »

J M Fahey

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #4 on: November 04, 2010, 06:23:08 PM »
Quote
I am not sure I would be able to design such big pcb
Me neither, and have been doing it for over 30 years.
Truth is, boards this complex usually are designed by some PCB suppliers, who have people who do this everyday , even nominally  "for free" , but who expect to get your 20000 boards a month order.
You *may* print that board image 4x the real size, then very carefully trace over it with India ink, some technical pens, a fine artist's brush, etc. , on vellum (transparent drawing paper) and "extract" the copper-only image , but  even so it's a lot of trouble.
You can build a commercial power amp from a kit , that's 90% of the job, and ,say, a Dr Booget or Dr Tweed or something like that to drive it.
Even a Guv'nor, for which you do find boards and layouts, is in fact the distortion channel of some Marshalls.
Start with that, in the future you can add another channel, effects loop, reverb, but go step by step, playing along.
Those 50W LM3886 kits sound very good and are loud, only asking you to use a good speaker.
As a curiosity, where are you writing from?
Maybe we can suggest you something else, based on that.

kin0

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #5 on: November 05, 2010, 01:20:47 AM »
I am writing from Israel.

I decided to build the randall rg80\100 es preamp (with both clean and dist channels) with poweramp kit (by the way which one do you recommend. I want it to be good for gigs\home\and to be able to play with drums).
I found a schematic but it is very complex and I can't isolate the preamp.
Also I don't know how to power up the power amp+preamp from one saurce?
Oh and how can I cancel the reverb (but leave the fx loop).

Oh and can I build the preamp with the rg100\80 dist channel and the clean channel from another amp with better clean (more fender clean for blues and funk mostly).
« Last Edit: November 05, 2010, 11:10:33 AM by kin0 »

J M Fahey

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #6 on: November 05, 2010, 11:18:28 AM »
OK, search what amplifier kits (50 to 120W) you can find locally and post a couple links to the most promising ones.
If you can order from US or Europe/UK say so, it's easier.
Post the Randall schematic (I have one but let's all use the same version) and I'll draw a colored box around what you'll need.
It can be split in various modules, so you can build, say, the dirty preamp and start playing quickly, then add the loop, later the clean channel and switching, then the reverb (if you can get a reverb tank).
Tell me about the possibilities for an electronics hobbyist there.
I know that for Defense purposes the highest level electronics are available, we used Israeli Dagger jets, Shafrir missiles, etc. in the Falklands War, but that's a Government to Government deal, don't know what the regular guy on the street , like you or me, can get on a regular shop.
Anyway you'll need PCB making materials, to roll your own, plus getting some experience on the software.
Express PCB is quite user friendly.
If it proves complicated or takes too long, I suggest you build one of the Marshall pedals /Guv'nor, Shredmaster, Jackhammer) for which you get a PCB design on some Forums.
They are the distortion channel from a Valvestate, minus the tube, and sound very good.
Once you decide on what power amp to build, it's easy to get the +24V or +9V to feed the Randall preamp or one of the pedals.
Good luck.
PS: I suggest you make an aluminum chassis with a lot of pot and jack holes, plus a few switches, where you mount the power amp and supply and any preamp you want to test.
You'll be able to play live with it, and modify it at will.

kin0

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #7 on: November 05, 2010, 11:47:45 AM »
Well the possibilities suck. The components aren't really great quality and there no different types (there is only ceramic resistors) and they are pretty expensive. I usually order kits and components from the US (but to order an amp is much harder and you pay a lot of taxes for it). I can't find any lm3886 kits (from USA) so if you have a good one (the cheaper the better) and I also prefer a 80-100 watt power amp (cause it is ss it it is not need to be at high volume for gain so I can use a high watt amp at home too right?) . Oh and I think I'll build it at one shot but in pieces because it will be easier to debag (I never debagged anything caues til now I got lucky).
I added a schematic


Okay I found a kit: http://www.chipamp.com/lm3886.shtml
1. which one should I buy (mono kit/stereo kit/dual mono kit)
2. How much watt is it?
3. in this pic http://www.briangt.com/gallery/lm3886amp/proto_amp_5 there is alot of other stuff. Do I need to buy it or does it comes with the kit (Also what does each one of them do? (I only recognize pcb and one pot)

Oh and what about the two channels form different amps (U thought of tech21 trademark 60 cause I am not sure if the clean channel of the randall with a ts is good enough for SRV blues )
« Last Edit: November 06, 2010, 12:33:26 PM by kin0 »

J M Fahey

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #8 on: November 07, 2010, 01:11:14 AM »
Thanks for your info on the average experimenter there.
Starting with the power amp kit, it looks that it will work.
Read many times the assembly manual, look at the pictures, etc.; every time you read it you will understand something new.
I think your best bet will be the dual mono.
You can build a very loud 2x12" combo, or a 1x12" (still quite loud) and later an extension speaker; everyday you use the 1x12 combo on its own, and in larger places, both.
I think you have 220V; state so to the kit provider so he sends you the correct transformer.
On the picture you show, I can see 2 mono boards, bolted to the chassis as heatsinks, a PSU board, a transformer and assorted hardware (switches, jacks, etc.)
You will still need to get a chassis, suitable heatsinks, and build some kind of preamp.
You might want to start with an intermediate 10/15W amplifier to hone your skills, which can be powered by a *very* common 12V transformer, and drive surplus car-type speakers, which you may even get for free from some junkyard or friendly mechanic.
Take it as a practice lesson, you get to keep and play it, and will have less doubts when building the larger one.
You can still drive it with a Guv'nor clone, which is easily powered "free" from the main power supply.
This way it will be much easier and cheaper (not to mention the Customs hassle) to get everything locally.
You'll feel good after building it.

kin0

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #9 on: November 07, 2010, 09:08:40 AM »
Okay I chose to use a shred master as a dist channel and I need to find a clean channel (I though about the tonemender but some say it pretty sucks). Also I need ideas for power amps (If it is not kit it will be better cause the kits are expensive).
« Last Edit: November 07, 2010, 02:27:04 PM by kin0 »

bry melvin

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #10 on: November 07, 2010, 05:52:20 PM »
There are several China/Honkong based outfits with high ratings that have 7293/4 and 3886 amp boards kit and finished. I have bought a few of these boards for TDA20x0s without problems Have also bought bulk resistors etc also.

Just search TDA7294 or LM3886 on ebay

J M Fahey

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #11 on: November 07, 2010, 09:30:13 PM »
Hi Kin.
The suggestion above is good.
Anyway I will post a link for a TDA2003 based 8W power amp kit, (European made, 15U$S) which has the added advantage that it can be powered by a 12V wall wart which you can find there for peanuts, saving moving transformers by mail which is relatively expensive. It will also power your preamp.
You can also use any speaker you find, and put it in any enclosure without feeling ashamed, be creative and have fun, it's an experiment!!
Build it, (with the ShredMaster as a preamp) and annoy your neighbours, you will have power enough for that.
With that experience, in a short time you can build a larger one.
I'm not at home now (still Sunday night here) but tomorrow I'll post.
« Last Edit: November 07, 2010, 09:45:41 PM by J M Fahey »

kin0

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #12 on: November 08, 2010, 10:10:35 AM »
I looked for lm3886 and tda7294 kits and all are 80w plus. I want it too be at least 15watt so I think I'll go with higher volt power supply (but I have no ideas how to build it and how to adjust it to 220 volt which we use in Israel. I understand in America you use less). For preamp I will go with shredmaster and tone mender and maybe later I'll add an fx loop. Still I don't know which power amp to build and what to do with the power supply. I prefer cheap stuff cause I am a teen and I don't have a lot of money (But lots of resistors and capatitors).

To get 18volt biopolar power supply can I first use this to get form 9v a 18v http://www.geofex.com/circuits/+9_to_33.htm
and then use this to make it bipolar http://gaussmarkov.net/wordpress/circuits/bipolar-9v-power-supply/?
« Last Edit: November 08, 2010, 01:01:33 PM by kin0 »

J M Fahey

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #13 on: November 08, 2010, 09:21:56 PM »
Hi kin.
Those power supplies are not enough, they are very low power, only suitable for pedals.
You will need a "real" transformer, with 220V primary.
I suggest you buy that in Israel, becuse they are heavy and bulky and postage will be a significant part of the cost, not forgetting Customs.
Yesterday I had suggested this:
http://www.vellemanusa.com/us/enu/product/view/?id=350529
which costs U$15 and can be powered by a wall-wart, which you can even get for free or very low cost (SEGA or Car Stereo power supply, etc.)
Don't know why they call it 4 or 5 W RMS; The original datasheet calls it 10W and you can even get 12W :
http://www.google.com/url?sa=t&source=web&cd=1&ved=0CBkQFjAA&url=http%3A%2F%2Fwww.st.com%2Fstonline%2Fbooks%2Fpdf%2Fdocs%2F1449.pdf&rct=j&q=tda2003&ei=u6nYTNmTC8ewngffvcHPCQ&usg=AFQjCNFbVnZKkk9l2OdV0jn7m45Wq3UZGw&cad=rja
the beauty of it is that in the Velleman instructions they even show how to add an input volume control, how to hook the Power Supply and the speaker:
http://www.vellemanusa.com/downloads/0/illustrated/illustrated_assembly_manual_k4001.pdf
You can use it as is, without preamp, as a practice amp.
You can advance your electronics building skills , have fun, later add the Shredmaster and in the future, replace the power amp with a louder one, such as:
http://www.vellemanusa.com/us/enu/product/view/?id=522104
It's 100W RMS into 4 ohms, a *very* serious amplifier, louder than the Bandit, in the same class as the Randall.
What I like about Velleman is the excellent assembly manual they provide, and all of them are written in a similar style; you learn one and have half-learnt the next.
Good luck.


kin0

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Re: Want to build a peavey bandit 112 redline or Randall RX120D
« Reply #14 on: November 09, 2010, 09:27:45 AM »
Okay I'll build this preamp (the small one) but do I need a heat sink for the preamp, and how much ohm does is produces (can I use it with the speaker of an mg15cd). Also is the tone mender a good preamp? The channel switching will be a 3pdt and two will switch between the input and output of the preamps and the third one will select to which preamp the power will go. Do you know how can I add a footswitch (and the regular switch on the amp)?
Oh also the kit needs 15volt not 12. Oh and where can I get a 12V power supply which will work with 220v (I can't find any good one in Israel)
« Last Edit: November 09, 2010, 10:21:07 AM by kin0 »