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Old 2nd June 2006, 09:23 AM   #11
dfdye is offline dfdye  United States
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Quote:
Originally posted by lndm
. . . However I would not compare valves and gainclones. I think their strengths lie in different areas.
Fair enough. I happen to like my gainclone, but never really have been a big fan of tubes (at least not the ones that fit my budget). Go figure!

Anyway, some people think gainclones have a "more laid back, tubey sound" than most SS amps. Just though I would pass it on. . .
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Old 2nd June 2006, 09:24 AM   #12
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I feel that gainclones are a terrrific stating point, I have now built 6 or so, they are however very tuneable once you start to play.

I don't think a std clone is really comparable in sound to a tube amp, however I can say that an LM1875 based clone. running on 12V smps power and with lowered gain and plenty of capacitor reserves does indeed sound a lot like a nice tube amp. The power output is pretty similar too.

The downside is that building an amp like this requires a lot more attention to detail to avoid oscillation, but it is still cheap.

The gainclones to my ears sound very different on lower volatage supplies regardless of the chip used, but only the LM1875 approaches the valve sound.

Surprisingly with about 4700 uf caps the 12v smps clones produce amazing tight bass without sacrificing highs.

The really neat thing is that you can easily build bi-amped and triamped systems with modules optimised for the frequency range you are working with.

A while back I tried using a 5v smps supply clone with small caps for tweeters, it produced micro detailed highs like you wouln't believe, it also made a good headphone amp, the output was probably only a watt and half, but for a tweeter this is fine.

Overall I'd say have a play, theres a good chance you'll move onto something else eventually but a good DIY amp of any type is likely to find a home someehere in your house when replaced, such as part of you computer set etc. I say start cheap, learn and have some fun.

Oh and if you want to use a transformer supply, you can get very nice results with cheap regular transformers, for example Dick Smith Electronics in OZ sells a 2 amp transformer
( M 1991 ) which is just $10.00 and powers an LM1875 clone very nicely, heck one for each channel is only $20.00! LOts of cheap Oz clones have been built with this!
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Old 2nd June 2006, 06:16 PM   #13
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50 watts is PLENTY for a pair of fe166e, and its even plenty for a pair of energy c-1(my other speakers).

i think, that i WILL build the lm388(?) amps, now i just need to find a place to source transformers from in canada.

also since im building the dual monos, i will need a preamp no? this i do not have unfortunately. but when it comes to pramps all i need is a volume knob!

SO i have a couple more questions for you guys, does anyone of you happen to know of any tutorials/build diaries for a chip amp? also anyone know of places to get transformers in canada?

and thirdly thanks to all who helped, yesterday i was lost, today i know what direction im going in, thanks a bunch.
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Old 2nd June 2006, 06:23 PM   #14
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also once again SORRY FOR THE DOUBLE POST!

but i will be (probably) ordering from audiosector, but which kit should i order? also it doesnt look liek they come with power supplies like they do at chipamp.com. maybe im jsut reading stuff wrong.

also can someone reccomend the range of sizes for toroidal and non toroidal transformers? this will help me find one.

for heatsinks do you NEED to use a special machined one? or will a 1/4" thick pannel of 6061(i think) aluminium be fine?
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Old 2nd June 2006, 07:02 PM   #15
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I've used nothing but Haflers for many years and have sampled the sound of several different models, plus made comparisons to those with the Musical Concepts circuit cards. My favorite for lower power and price is the Hafler 9180 or the DH-120.

They both put out 65 watts per channel and use the same circuit. The 9180 is a little newer and a bit pricier but it has a few polyprop film caps in certain places that the DH-120 uses mylar -- hence a slight improvement in the upper mids. And, there are guys who mod their DH-120s with these film caps and are pleased with the results.

These amps hold their value so if you don't like one, just sell it for about what you paid for it.

My $0.02
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Old 2nd June 2006, 07:06 PM   #16
preiter is offline preiter  United States
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Go do some reading in the chipamp forum, all of your answers about gainclones are in there. Also try the decibel dungeon site for lots of gainclone info.

The lm3886 has plenty of clean, solid power (it's loud enough for me with my very inefficient Dayton BR-1 kit speakers).

Just about any old heatsink will be just fine.
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Old 2nd June 2006, 11:26 PM   #17
lndm is offline lndm  Australia
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A starting point straight out of a catalogue, LM3876 (per module): +/-35V @ 80VA = 25+25 toroid @ 160VA, 2,200uF/50V x 2, heatsink 1.4 degrees C per watt (2.5F?).
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Old 2nd June 2006, 11:48 PM   #18
dfdye is offline dfdye  United States
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The audiosector LM3875 Dual Mono Classic Kit
http://www.audiosector.com/lm3875.shtml should get you started quite well. It comes with two rectifier boards and two amps (so yes, the power supply is included here). The documentation Peter has on his site should answer most of your basic assembly questions. (there is even a section on soldering, since you said you didn't have much experience.)

Also, you can easily use a 2 gang pot as a "passive preamp" (though this technically isn't a preamp since it doesn't amplify anything!). There are even instructions on how to do this in the documentation.

Finally, I'll second the 160VA transformer as being sufficient, though I have used +/-21V secondaries with good success. Higher voltages are often a little moody with harder to drive loads, so keep that in mind when picking rail voltages. Anywhere between 18 and 25V for the transformer secondaries should suit you well, though.
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Old 3rd June 2006, 12:22 AM   #19
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Considering your speakers are going to be very efficient there is little point in going for high power and thus large transformers, so stick to the smaller ones, less cost, less size and lower noise!

Let me put it this way, my current system runs Double Bass boxed 4 inch drivers (very similar to fostex 103s) with LM1875 based amp running on smps and low gain. It puts out probably 5 watts per channel and the drivers are 93db efficient, probably higher in the boxes though.

Bottom line, this system produces ear splitting sound levels in my 18 by 12 room, but with very high clarity, the fostex 166s etc should be even more efficient, so forget about the max power output it fairly irelevant in your situation even allowing for transients etc. The difference in power requirments between a low efficiency bookshelf speaker at say 84db and yours are like a mouse to an elephant. You'd need all the watts you could muster for the 84db ones.

I would say that most of the time you'd be using 1/10watt or less.

You could even run the 3886s on lower voltage, cheaper again and it will sound sweeter in the highs. From experience the main changes in sound will be dirived from the power supply set-up, including the size of the bypass caps.

Two options for really serious consideration SMPS or Battery power, both in my opinion take the clone to a whole new level, but start with the cheap transformer first.
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Old 3rd June 2006, 12:25 AM   #20
dfdye is offline dfdye  United States
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To clarify a point about the transformers, 160VA is total for the system. If you are running dual mono, you should be fine with 80VA per block.

David
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