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Author Topic: What have I got here?  (Read 4872 times)

One-way

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What have I got here?
« on: February 24, 2009, 02:21:13 AM »
Hi Folks,
I finally had time to take some pics of my US 5.00 amp parts.
I would like someone to tell me what exactly I have. I know it is two channel, (clean and dirty) and has a headphone socket and what looks like a line out. I cant get in touch with the guy who built it so haven't a schematic to work off. I does go but is very quiet as several wires have broken off from being transported etc.
What I would like is for someone to point me to a schematic I could use to build a basic 2 channel amp like a Marshall or similar using these parts.
The power supply is a 160VA MT2114 25 + 25 volt 3.2 amp  6.4 amp.
What wattage would this be capable of?
I can supply more detail of individual parts if needed but it has a BB OPA2134PA AND OPA37GP opamps.
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0001-7.jpg
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0002-7.jpg
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0004-6.jpg
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0005-3.jpg
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0007.jpg
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0008-2.jpg
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0009-3.jpg
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0010-1.jpg
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0012-1.jpg
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0013.jpg
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0014-1.jpg
http://i54.photobucket.com/albums/g111/One-Way/2003_0101Image0015-2.jpg

« Last Edit: February 24, 2009, 02:23:20 AM by One-way »

syndromet

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Re: What have I got here?
« Reply #1 on: February 24, 2009, 07:53:56 AM »
To me it looks like something worth fixing....

J M Fahey

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Re: What have I got here?
« Reply #2 on: February 24, 2009, 01:27:13 PM »
I agree with Syndromet. At least you got an expensive transformer, power supply, working power amp, a lot of pots, a relay and some re-usable spare parts.
You should try to get some kind of chassis; this one is full of cut wires because of the moving and juggling around.
At the very least, you *can* get along with a wooden "floor" but you´ll need a sheet metal or extruded aluminum front panel (a back panel wouldn´t hurt either) firmly screwed to it.
Without an schematic and not being a commercial product, it becomes impossible to help you beyond that, I guess you´ll first build some clean preamp and later add-on part by part.
J M

One-way

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Re: What have I got here?
« Reply #3 on: February 25, 2009, 02:31:43 AM »
The plan is to reuse the components. I want to find a suitable schematic and re-fit the needed components using new Vero board so I can follow the schematic bit by bit. That way I can learn as I can go and gain an understanding of how all the bits fit together.
I can easily fold up a chassis being an Engineer by trade and plan to make it into a head unit as I have a 1x12" cab I built recently.
Some questions:
Is the power supply capable of 50 volts being 25+25 volts?
What wattage capability has the power supply and how do you match it with opamps etc.
Sorry Im not yet knowledgeable when it comes to the components and what they actually do but I am determined to learn.
 
« Last Edit: February 25, 2009, 02:33:22 AM by One-way »

J M Fahey

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Re: What have I got here?
« Reply #4 on: February 25, 2009, 07:52:11 AM »
Hi One Way
Being an Engineer surely helps !!
Having access to some kind of metal shop is even better.
The worst problem for experimentors and hobbyists is the "mechanical" part.
"Small" projects, those which can be built on one board, powered by batteries or some wall-wart and which can work without an enclosure or which are happy with some kind of plastic case, are best.
I suggest you download Teemuk´s *excellent* book; various datasheets as needed, and make an "universal" chassis, with a lot of holes for pots, jacks and switches in the front panel.
That way you can mount firmly your power amp and supply, and experiment at will with various preamps, effects, etc.
If possible use aluminum: easy to work, doesn´t rust nor need paint or other protection,etc.
I found this veroboard PCB designer software very useful:
DIY Layout Creator:
http://www.storm-software.co.yu/diy/
It already comes with a lot of useful projects already designed and tested.
Bye.
J M Fahey
« Last Edit: February 25, 2009, 07:54:42 AM by J M Fahey »

One-way

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Re: What have I got here?
« Reply #5 on: March 03, 2009, 04:30:16 AM »
I have access to a well equipped high school workshop so the chassis is not a problem. I even have some aluminium sheet earmarked for one. I am nearly finished building a passive volume pedal which I folded out of Ali plate. Just need a couple of jacks and I can wire it and test.
What I need to know to kick start this amp project is two things.
I want to know what the actual voltage the Toroid secondary puts out as what Ive read that the 25 + 25 actually puts out 35 Volts. I assume this varies with the amperage loading?
From the bunch of schematics Ive looked at lots run at 15 volts, some 25, 35 and other higher. I want a basic probably 2 channel schematic that will use the suit the max output of the Toroid. The Elliot 100 watt design uses the same model Toroid design as I have but I see in another thread folks think the pre amp design is very basic and can be improved on.
I would like to build a 1oo watter if possible using something like a solid state Marshall schematic without any effects. Can anyone actually point me to a schematic that would suit the Toroid and end up with an amp that rocks.
Thanks in advance.


J M Fahey

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Re: What have I got here?
« Reply #6 on: March 03, 2009, 02:02:01 PM »
Hi. If that´s what you want, good.
Your toroid supplies +-35V.D.C, which is great for an LM3886. I think you already have something like that.
A commercial preamp I suggest you copy is Marshall´s Lead12, a killer 12 watter from the 80´s. I think the schematic was called "3005" or something like that.
It was so good that Billy Gibbons (ZZ Top) rackmounted one of them, to use it live.
It only uses an LM1458 (you can use RC4558 or TL072), and will easily drive your power amp.
Bye.

One-way

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Re: What have I got here?
« Reply #7 on: March 04, 2009, 04:27:11 AM »
Thanks for that info JM.
I dont know why the Toroid manufacturers dont give the actual secondary voltage. I guess it fairly typical of Chinese manufactured stuff that the specs are absolutely basic and aren't listed anywhere. I recently bought a cheap tube output transformer at auction for an all tube amp project at some stage that is rated at 10 watts but the technical specs are unknown.
I will look into those schematics you suggest.

J M Fahey

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Re: What have I got here?
« Reply #8 on: March 04, 2009, 07:45:39 AM »
Hi One Way.
I think I must rephrase my earlier answer. In fact the toroid *does* supply 25+25 Volts A.C. , and it´s correctly labeled. What I should have added more clearly  it that such a transformer, *hooked to a bridge rectifier and 2 capacitors* will supply 35+35 Volts D.C. , which is the peak value of the 25+25V senoid. You suspect right, that voltage goes down somewhat with high volume (up to 20%), but don´t worry, that's  accounted for in the design. Engineers must live in and design for the "real world". Good luck.

One-way

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Re: What have I got here?
« Reply #9 on: March 05, 2009, 02:02:27 AM »
Yes thanks for that.
Now it makes sense that the rectifier and Caps boost the voltage. Im learning new stuff about circuits every day.

 

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