Commercial complete Gainclone kit for a beginner?

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I have soldered before, is there a complete kit (including tranformer, power supply etc) to try a Gainclone for strictly plug one end on the wall outlet and connect to my DIY speaker (fullrange).

I can follow a "pictural how to" but not schematic, would prefer to order all in one kit form, is there a vendor for this?

thanks,

gychang
 
Hi Gychang -

I can't help you but am on a similar quest.

I'm a Fan of yours from your B20 project and followed many of your other projects.

I had thought you'd done a gainclone and had troubles with the 1st one? If I'm correct can you elaborate? I can't afford $100 mistakes. Your answer will help me know what to avoid.

I've e-mailed 3 manufacturers to date with questions regards their instructions being clear enough for a newbee to handle and I don't even get replies.

Hope you get some feedback on this, seems 10,000 built them but had some 'Universal Knowledge' the rest of us don't possess.

Bluto
 
I just finished the BrianGT chipamp.com 3886 kit - I know very little about electricity, can't read a schematic, and that was my first kit ever. I am surprisingly good with a soldiering iron, so that made it very easy.

The instructions at chipamp.com - ok, but not so great. AudioSector.com has a very similar kit, and the instructions/manual on the site is very easy to follow and has some pictures - I have never put that kit together, but I wish I had gone with the audiosector kit simply due to the ease of instruction included.

Neither kit comes with a transformer/toroid, plugs, cords, connectors, or a chassis. Those can be had fairly cheaply if you dig around, so don't be afraid to try some experimenting and hand craft some components for your amp.

However, now I believe I am a professional and can't wait to build my own custom 300b single-ended tube amp - NOT
 
Gychang,
I bet that with a piece of proto-board, a couple 3875's and a handful of components you CAN make an amp that you'll enjoy a great deal. There is certainly nothing wrong with the kit route, but from scratch is VERY attainable.
Print out the schematic in question and physically lay each component over it's symbol. Add a wire for each line and voila... noise, er-ahh MUSIC:D


7/10
 
gychang said:
I have soldered before, is there a complete kit (including tranformer, power supply etc) to try a Gainclone for strictly plug one end on the wall outlet and connect to my DIY speaker (fullrange).

I can follow a "pictural how to" but not schematic, would prefer to order all in one kit form, is there a vendor for this?

thanks, gychang

Complete? That's a rather important concept.
And here's a caveat:
Complete, as in achieving advertised results, also involves a preamplifier. The chip amp is a power amp, technically incomplete without a preamplifier.

Brian, BWRX, has two chipamps that include the preamp /w regulator, and this is the most complete design that I'm aware of. See www.transientharmony.com


Let's look at it from a "module" viewpoint:
Power amp
Power supply
Preamp /w regulator
Transformer
Chassis /w heatsink

Although the module viewpoint looks intense at first glance, actually its easier in practice--because this makes for several small projects instead of one large unit.
(Approach is, several smaller problems instead of a big problem.)

That's enough for one post.
I will follow up with more later, and possibly a few shortcuts.
 
For beginner use, chips with only five connections may be easiest. Those are LM3875 and LM1875. Both have five active pins.

Select either LM3875's 55 watts and plan to use a preamp,
or
select LM1875's 25 watts.


The purpose of a preamp is so that you don't have to increase the distortion with a gain of 45 on a power amp. Instead, the preamp does a portion of the gain and the power amp does a portion of the gain--with no stress on either.


Next, its transformer shopping time.
How to select?

Take the "watts output" of your amplifier and multiply by 1.5 to get the VA requirement for transformer.

Here's an example of VA, volt ampers: A 36v center tap (18+18 ac) transformer with 1 amper makes 36va.

Relating back to LM1875 above, 25 watts x 1.5 = 37.5, so you can see that the 36vct (18+18 ac), 36va transformer above can probably run a single LM1875 monobloc per each transformer.

Relating back to LM3875 above, 55 watts x 1.5 = 82.5. And, I didn't mention it yet, but LM3875 likes a 48vct (24+24 ac) transformer. That's 1.72 ampers. You can readily find 2 amper rated 48v (2a x 48v = 96va) center tap transformers, and that can run a single LM3875 monobloc per each transformer.

Stereo sidenote:
Although I'm going to cover monoblocs, here's a note for stereo layout. That implies using just one transformer running two amplifiers. Simply use double the VA, meaning select a transformer that's twice as strong. For the final note on stereo layout, its nice to have any left side connections exactly the same length as any right side connections.

My own personal preference is monobloc layout, inferring that each amp chip has its own transformer (no matter how few or how many are inside a given chassis/enclosure). Advantages and disadvantages are well documented, so you can decide for yourself.


And now where are we?
Hopefully, there's enough information in this post that you have selected a power amplifier and a transformer to match.

That's enough for now.
More to follow. . .
 
This photo illustrates where the five connections go.

Right side is speaker output with a protection zobel (pitched higher than the audio band)

Center is the power circuit.
The two small ceramic are 100nF (0.1uF, Bar 104).
The two large e-caps pictured are 220uF, although you could use 330uF or 470uF.

Top left is the NFB, Negative Feedback Loop, that is responsible for setting the gain. It is normally two resistors, although the presence of a optional 22uF (or greater) cap there indicates potential for using this particular amplifier without a preamp, as a cap there can prevent the amplifier from amplifying DC (makes zero dc offset).

Center left is shown an optional "ground lift" resistor, as you can see it connecting the ground of both NFB and inputer circuit (input star ground) over to the power ground. It can be 0R, 4R or 10R.

Lower left is the input circuit. There are many options shown.
Going in order from left-center to lowest left. . .
Most important at the input circuit is the resistor from input + to input -, as this presents a load for the source to drive.
Next is the small 330pF (Bar 331) ceramic cap, also a load, as this shunts away stray RF signals.
The ecap is a dc blocking filter, aka input filter cap.
Next is a 1 megaohm resistor set as a load.
Lowest left is a 1k resistor (optional) providing isolation, but also affecting tonality (can use any "pleasant" value there or 0).


See photo and compare to the circuit in the PDF's above.
EDIT: As you can see, this doesn't require a kit.
 

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Kits:
(listed because their documents and photos can be useful)
K50 (QK50)
http://www.electronics123.com/s.nl/it.A/id.425/.f
K50 document
http://www.electronics123.net/amazon/datasheet/k50.pdf
K50 spare Printed Circuit Boards (without components)
http://www.electronics123.com/s.nl/it.A/id.1801/.f
*not exactly hifi as shipped, but can be modded easily by installing better components.

Basic power:
http://www.electronics123.com/s.nl/it.A/id.347/.f
power document
http://electronics123.net/amazon/datasheet/k114.pdf
*you can make better for less, but the document is fantastic.

Preamp:
http://www.electronics123.com/s.nl/it.A/id.311/.f
preamp document
http://electronics123.net/amazon/datasheet/k100.pdf
*an adjustable preamp that doesn't run your signal through a bunch of potentiometers

Flux:
http://www.radioshack.com/product/i...p=&sr=1&origkw=flux&kw=flux&parentPage=search
*this is quite necessary for neat, easy, soldering--can use #0000 steel wool to wipe carbonized flux off from the soldering iron tip to maintain a bright, glossy, silver color at each solder joint.

Iron:
http://www.radioshack.com/product/i...=desoldering&kw=desoldering&parentPage=search
*a bit short on power, but it won't hurt components

Desoldering iron:
http://www.radioshack.com/product/i...=desoldering&kw=desoldering&parentPage=search
*this tool removes errors quickly

Another useful tool is a multimeter that's sensitive to DC (and readable at millivolts) so that you can check the dc offset of the amplifier before connecting speakers.
 
gychang said:
I have soldered before, is there a complete kit (including tranformer, power supply etc) to try a Gainclone for strictly plug one end on the wall outlet and connect to my DIY speaker (fullrange).

I can follow a "pictural how to" but not schematic, would prefer to order all in one kit form, is there a vendor for this?

Yes, although I don't adverise it, the chassis pictured here: http://audiosector.com/chassis_integrated.shtml is available as a kit as well all other needed parts:

Premium GC kit, Noble pot, Knobs, Wooden sides, Shaft extenders, RCAs, Cardas patented binding posts, Source selector, AC module, Brass cones, Plitron 300VA toroid

You can build a complete amp as pictured, or use only selected parts and be able to connect amp to the speakers.
 
Gychang -

I looked into gainclones a bit over a year ago. Got discouraged as so many were so far ahead and I couldn't find simple instructions for an easy one. Guys already had them modded to the max.

I'm looking again as I'm interested in the concept of separates.

If you're up to a 'scratch' build and want another (well, me anyhow) Dummy to work with on this I'd be happy to work with you. Apex JR. has 3886 chips for less than $4.

Don't want to steal your thread.

Bluto
 
danielwritesbac said:
For beginner use, chips with only five connections may be easiest. Those are LM3875 and LM1875. Both have five active pins.

Select either LM3875's 55 watts and plan to use a preamp,
or
select LM1875's 25 watts.


The purpose of a preamp is so that you don't have to increase the distortion with a gain of 45 on a power amp. Instead, the preamp does a portion of the gain and the power amp does a portion of the gain--with no stress on either.


Next, its transformer shopping time.
How to select?

Take the "watts output" of your amplifier and multiply by 1.5 to get the VA requirement for transformer.

Here's an example of VA, volt ampers: A 36v center tap (18+18 ac) transformer with 1 amper makes 36va.

Relating back to LM1875 above, 25 watts x 1.5 = 37.5, so you can see that the 36vct (18+18 ac), 36va transformer above can probably run a single LM1875 monobloc per each transformer.

Relating back to LM3875 above, 55 watts x 1.5 = 82.5. And, I didn't mention it yet, but LM3875 likes a 48vct (24+24 ac) transformer. That's 1.72 ampers. You can readily find 2 amper rated 48v (2a x 48v = 96va) center tap transformers, and that can run a single LM3875 monobloc per each transformer.

Stereo sidenote:
Although I'm going to cover monoblocs, here's a note for stereo layout. That implies using just one transformer running two amplifiers. Simply use double the VA, meaning select a transformer that's twice as strong. For the final note on stereo layout, its nice to have any left side connections exactly the same length as any right side connections.

My own personal preference is monobloc layout, inferring that each amp chip has its own transformer (no matter how few or how many are inside a given chassis/enclosure). Advantages and disadvantages are well documented, so you can decide for yourself.


And now where are we?
Hopefully, there's enough information in this post that you have selected a power amplifier and a transformer to match.

That's enough for now.
More to follow. . .


I really appreciate all these valuable tips, very helpful, learning quickly but I am old enough things don't click well...

I hope u don't mind more newbie questions to follow, again thanks for all the details to get me started.

gychang
 
Bluto said:
Gychang -

I'm looking again as I'm interested in the concept of separates.

If you're up to a 'scratch' build and want another (well, me anyhow) Dummy to work with on this I'd be happy to work with you. Apex JR. has 3886 chips for less than $4.

Don't want to steal your thread.

Bluto

Bluto, let's do this thing together, I am sure I am dummer than you. As this thread is useful for a newbie, perhaps our conversation will be helpful to others.

Let me look at the chip at Apex JR. Any other parts that can be ordered from the same vendor? transformer?, heat sink? etc. I am particularly interested in about 50W output model.

gychang
 
danielwritesbac said:
About 50 watts.
That's LM3875 with a 48vct (or 24+24 vac) transformer. EDIT: about 2 ampers per chip.

Of the eleven pins of LM3875, 6 are N.C. (no connection), thus leaving only 5 connections to deal with. ;)
EDIT2: See the first page of http://www.national.com/ds.cgi/LM/LM3875.pdf


thanks, is there a proper t/former on this page?, Bluto suggested we order parts from ApexJr.

http://www.apexjr.com/miscellaneous.html

will have to order 2 since your previous suggestion of each t/former per channel may be better.

gychang
 
gychang said:

thanks, is there a proper t/former on this page?, Bluto suggested we order parts from ApexJr.

http://www.national.com/ds.cgi/LM/LM3875.pdf

will have to order 2 since your previous suggestion of each t/former per channel may be better.

gychang

There is debate on whether monobloc format is better or not. I'd encourage you to research that one.

Here's an inexpensive transformer that works quite well: http://www.alliedelec.com/Search/ProductDetail.asp?SKU=967-7473 each does one lm3875

You'll also need 4 of 10nf ceramic cap, per each bridge rectifier IF using a center tap transformer.

Here's an easy bridge rectifier:
http://www.alliedelec.com/Search/ProductDetail.asp?SKU=266-0047

Power supply caps:
http://www.alliedelec.com/Search/ProductDetail.asp?SKU=862-0135
About four of those per transformer will give you 9400uF rails.

EDIT: At this time, it would be good to make a shopping list rather than purchasing immediately, because, with a little patience and research, you can reduce shipping expense.
 
Hi Gychang -

Sent you a PM.

See more info has arrived. Good point regards helping other newbees who got left behind when the wave came in.

What should we call the thread? How bout '50 watt per channel Dual Dummies' ?

Be forewarned, I'm the guy who started the thread entitled 'electrocution not an option'.

We could turn out to be an inspiration to lurkers, on the other hand , obvious Fools.

Hmmm ...

Bluto
 
DWB & 7/10ths -

Thanks for all the input on this. That's mucho work and appreciated.

I just got the new Digikey Catalog 2 days ago, can't believe those people send me that 40# monster yearly, gotta cost a fortune to print that thing.

I sourced a bunch of needed stuff long ago, a real deal ( me thinks) on heat sinks through an Ebay store I saved as well . We'll do price comparisons with what you provided.

I was familiar with the Dogbreath design and part of the reason I hadn't given up hope, Elliots stuff is good to read and understand 'why' with but too hard for this newbee and his schematics and a soldering iron to risk actual MONEY over.

I'm a year away from serious reading on the subject and just got started again about 2 weeks ago. Already things have moved light years again. Power needed is obvious concern but what I'm picking up is most guys like the 3886 above the 3875. We need a design 1st so everyones input appreciated.

No more to say, it's Gychangs thread and until we talk I'm speechless.

Bluto
 
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