Author Topic: gainclones diy anyone? (Read 383279 times)

joan2 · « **Reply #90 on:** Oct 05, 2003 at 11:16 AM »

guys,
how about this, you can buy surplus amps, price is about "1500 as - is" or you can go to the pier where they sell these stuff and get one which is unrepairable, an integrated amp would be nice as you can use the preamp section, choose one which has main filter caps with voltage ratings of 50volts or less...this way you can have a gainclone amp that looks like a branded one, i m willing to guide and assist anyone wanting to go this way!!!!

Garp · « **Reply #91 on:** Oct 06, 2003 at 05:33 PM »

Quote from: moonshow on Oct 03, 2003 at 07:17 PM

grap, where did you buy your insulation pads?the pads i used was mica and not really for ic chips.

i also noticed the heating of the heatsink after every tweak i did. the only time it normalized was when i perfected the grounding of the cicuit. btw. how big are your heatsinks? and what chips are you using? thanks

The heatsinks I used for the prototype were the usual type you see at Alexan about 3x4 inches with fins. But I'm going to use large heatsinks on the final that will double as sides for the amp case, so all i need is the front plate, back and top. Might just go with wood (thinking of lawanit para cheap lang) because they're easier to do. So far its the amp case that's given me a lot of headache.

Yes I noticed that if you're grounding is ok, the heatsink stays cool and the sound is as it should be. For insulation, I might use mica pads because I already have them. I used lm3875s for the prototype/rats' nest and Ill use these for the final.

joan2 · « **Reply #92 on:** Oct 06, 2003 at 10:59 PM »

garp,
i go for aluminum housing, i buy cut aluminum plates from sulimco metals in aranque, then have one of the local shops near by do the bending and forming for me. i use ga18 or 16 for covers, ga14 or ga13 for the main housing, this way, you may use the chassis as heatsink also....front panels, i also buy 3/16 in aluminum plates, then have it machined by a machine shop...aluminum is very easy to work with...you need an eletric drill, files, sandpapers... then you can have your housing anodized matte black, or any collor you like....gem metals in makati is one such shop...

Garp · « **Reply #93 on:** Oct 07, 2003 at 09:52 AM »

Great! Thanks for the info.

Leiko · « **Reply #94 on:** Oct 08, 2003 at 06:59 PM »

Interesting thread here... anyone got a BOM, where to get them and price? Any pics to share for completed projects? Congratz!!!

joan2 · « **Reply #95 on:** Oct 08, 2003 at 07:17 PM »

Leiko .
please read the earlier postings, you will find links to get your bom, fyi, these gainclones operates an an op amp, with higher supply rails +/-35, so you can configure these chips same way as you would an op amp....welcome to the club!!!....btw these chips can be purchased thru rs components at 450or so per chip...

here are some pics you might find interesting!!!
http://www.geocities.com/react_71/audio/index.htm

GC · « **Reply #96 on:** Oct 08, 2003 at 09:57 PM »

Quote from: joan2 on Oct 08, 2003 at 07:17 PM

here are some pics you might find interesting!!!
http://www.geocities.com/react_71/audio/index.htm

That's neat! Ayos yung pictures nung gainclones nya. Ano po bang mas ok, separate PCB's per channel or sa isang PCB lang sila?

joan2 · « **Reply #97 on:** Oct 09, 2003 at 06:36 AM »

no need to do pcb's, p2p is fine, this way you can make the signal path very short....

GC · « **Reply #98 on:** Oct 09, 2003 at 08:47 PM »

Quote from: joan2 on Oct 09, 2003 at 06:36 AM

no need to do pcb's, p2p is fine, this way you can make the signal path very short....

ok. thanks!

joan2 · « **Reply #99 on:** Oct 10, 2003 at 07:22 AM »

i got this dynaco sc120 circa 1966 ss amp for repair, looks like a good candidate for gainclone chassis if i can convince to owner to give to me to use in my gainclone project....

here is what it looks like:
http://home.indy.net/~gregdunn/dynaco/components/ST120/index.html

homer · « **Reply #100 on:** Oct 11, 2003 at 10:53 AM »

lm3886's are available at newport electronics evangelista for p270, p275 for isolated. bought 2 lm3886t's but can't confirm yet if these are origs.

joan2 · « **Reply #101 on:** Oct 11, 2003 at 04:03 PM »

homer,
this is great news, lm3886 sells for 450 at rs components in makati...i have the original lm3886 with me, i will check out the item at the store and will confirm to you if it is genuine or not.....i hope it is genuine....

akyatbundok · « **Reply #102 on:** Oct 13, 2003 at 04:42 PM »

there are some incredibly cool implementations of this amp design. i have no talent for doing this, but i drool at the prospect of owning one. papano naman kami... hehe.

1) http://www.geocities.com/react_71/audio/gainclone/gainclone_pics.htm

2) http://www.diyaudio.com/forums/showthread.php?s=&threadid=9112

joan2 · « **Reply #103 on:** Oct 13, 2003 at 05:45 PM »

akyat,
if you can solder, i can guide you to build one...nothing beats having amps built by your own hands....branded amps sure looks nice, but the one you make is one that you will enjoy the most.....

akyatbundok · « **Reply #104 on:** Oct 13, 2003 at 07:14 PM »

naku sir, takot ako dyan.. i once tried soldering a spy radio microphone kit and i burned the thing in 10secs..

im more of a software guy, and this leaning can be judged by the number of amps that've blown because of my clumsiness.. hehe. plus i live in a building where the fire alarms go off at the first hint of smoke. (daming palusot no?) anyway, im one of the curious bystanders here who are checking to see if this eventually becomes a project for the masses ala wiredstate. my dream - a custom tube preamp and monobloc ss power amps. maybe pinoydvd should have a list of projects for the members? a fellow member built a pretty good dvd rack for me for a good price.

Leiko · « **Reply #105 on:** Oct 14, 2003 at 07:56 AM »

Quote from: joan2 on Oct 11, 2003 at 04:03 PM

homer,
this is great news, lm3886 sells for 450 at rs components in makati...i have the original lm3886 with me, i will check out the item at the store and will confirm to you if it is genuine or not.....i hope it is genuine....

so are these genuine? how different are these from 3875?

btw, w/o refuelling the debate bet SS and valves... just to note that the discussion here about the topic is enlightening.

In this hobby, my priorities are pocket first, and ears next. SS has it's good points and valves has its own. It's a matter of where I use them... agree, it's a synergy of all components that makes a failthful music reproduction... not one or two pieces but ALL components kaya minsan napamahal yung hobby na 'to.

maybe, my upcoming venture into GAIN will change my belief!

homer · « **Reply #106 on:** Oct 14, 2003 at 08:22 AM »

http://www.jeffrowland.com/Concentra%20Page.htm
http://www.jeffrowland.com/review16b.htm
http://www.jeffrowland.com/review16d.htm
http://www.jeffrowland.com/review16c.htm

Garp · « **Reply #107 on:** Oct 14, 2003 at 09:51 AM »

Quote from: homer on Oct 14, 2003 at 08:22 AM

http://www.jeffrowland.com/Concentra%20Page.htm
http://www.jeffrowland.com/review16b.htm
http://www.jeffrowland.com/review16d.htm
http://www.jeffrowland.com/review16c.htm

Jeff Rowland uses LM3886!

akyatbundok · « **Reply #108 on:** Oct 14, 2003 at 10:24 AM »

is there a night class i could attend that teaches the basics in electronics? preferably with lab so i could practice... i want to learn!

joan2 · « **Reply #109 on:** Oct 14, 2003 at 12:20 PM »

Quote from: Leiko on Oct 14, 2003 at 07:56 AM

so are these genuine? how different are these from 3875?

btw, w/o refuelling the debate bet SS and valves... just to note that the discussion here about the topic is enlightening. In this hobby, my priorities are pocket first, and ears next. SS has it's good points and valves has its own. It's a matter of where I use them... agree, it's a synergy of all components that makes a failthful music reproduction... not one or two pieces but ALL components kaya minsan napamahal yung hobby na 'to.

maybe, my upcoming venture into GAIN will change my belief!

i haven't gone to raon yet, hopefully this week, the lm3886, has stand-by and muting functions, to save energy and to prevent turn-on/turn-off thumps that may be present as a consequence of hooking up your audio gear, the lm3875 on the other hand, has none of these functions, but take nothing out it, this chips is as simple as it can get...you can build the inverting gainclone with just a few components, no need to fab pcb's as p2p wiring will suffice, you can make the signal path as short as you can...best of all this is doable even by a complete newbie as demonstrated by moonshow...it took us about 4 phonecall sessions....this is definetly easier, cheaper, and safer to do as the parts are easy to get, and the voltages very low....nothing to lose, as even high end equipment uses this chip....

joan2 · « **Reply #110 on:** Oct 14, 2003 at 12:25 PM »

Quote from: akyatbundok on Oct 14, 2003 at 10:24 AM

is there a night class i could attend that teaches the basics in electronics? preferably with lab so i could practice... i want to learn!

i am willing to give lessons, if you can organize, the place or venue.....i can give you what i learned in 30 years in about 30 hours or so....

Garp · « **Reply #111 on:** Oct 14, 2003 at 01:47 PM »

Hey I'm a newbie too--my first DIY and it actually worked

(beginner's luck i guess).

For those who are interested to try but worry that if you make a mistake you'll ruin the chip (like I did with LM3875 and that cost me about P1K), the low-powered cousin LM1875 is widely available in Raon going for less than P100. Its a 5-pin chip and you can use the same schematic (note the pin configuration though) used for the LM3875 except the transformer which should have a secondary VAC of 21 max. If you have 18VAC secondaries, that's close to 24VDC on the rails with power output of about 25W. When you think you can get it right, then you can move from prototype to final version using better quality parts. I did the prototype using the cheapest parts available just to hear whether I will like the sound. It turns out I love the sound. I can't guarantee that you will too but I think it's worth a try.

Garp · « **Reply #112 on:** Oct 14, 2003 at 01:51 PM »

Quote from: joan2 on Oct 14, 2003 at 12:20 PM

ithis is definetly easier, cheaper, and safer to do as the parts are easy to get, and the voltages very low....nothing to lose, as even high end equipment uses this chip....

Agree. But in my case the accident is when I inadvertently grabbed the soldiering iron on the hot end. Lapnos yung kamay ko.

joan2 · « **Reply #113 on:** Oct 14, 2003 at 05:08 PM »

Quote from: Garp on Oct 14, 2003 at 01:51 PM

Agree. But in my case the accident is when I inadvertently grabbed the soldiering iron on the hot end. Lapnos yung kamay ko.

hindi ka nag-iisa, i still bear slight scars at the back of my hands from my tube days, they touched the hot side of the 450volt filter caps....

Leiko · « **Reply #114 on:** Oct 14, 2003 at 07:36 PM »

Quote from: Garp on Oct 14, 2003 at 01:47 PM

I did the prototype using the cheapest parts available just to hear whether I will like the sound. It turns out I love the sound. I can't guarantee that you will too but I think it's worth a try.

congratz!!! wish i have same luck on my own try. any comparison to the sound produced by your clone against your other amp/s?

joan2 · « **Reply #115 on:** Oct 15, 2003 at 09:27 AM »

Quote

congratz!!! wish i have same luck on my own try.

can't see why not!!! you can do it....

akyatbundok · « **Reply #116 on:** Oct 15, 2003 at 09:53 AM »

Quote from: joan2 on Oct 14, 2003 at 12:25 PM

i am willing to give lessons, if you can organize, the place or venue.....i can give you what i learned in 30 years in about 30 hours or so....

thanks for your generosity sir! i'll try to visit you this weekend, ill bring my "sick" amp.

Garp · « **Reply #117 on:** Oct 15, 2003 at 10:49 AM »

Quote from: Leiko on Oct 14, 2003 at 07:36 PM

congratz!!! wish i have same luck on my own try. any comparison to the sound produced by your clone against your other amp/s?

Thanks. But I ruined the chips as I was trying to add a buffer. In terms of sound ok I'll give you my impression but this comes with a big disclaimer because 1) My benchmark is only mid-fi--my onkyo receiver 2) I may be actually falling into "experimenter expectancy" here 3) I have not listened to it long enough to be sure I've broken it in.

The sound is very clear and detailed. Soundstage is wider and imaging is more precise. What's very noticeable is the bass control giving the impression that its "fast" and very lively. My observations are in line with the consensus here. The bad thing is its fatuiging. It's very edgy at the top. Vocals which were not sibilant in my Onkyo were sibilant in the gainclone. Again, this could be the result of the highs being too detailed. This is also what's reported by other DIYers but according to Peter Daniel, the way to improve the highs is by putting 4.7uf BG Non-polar caps across the rectifier diodes. This according to him cured the edgy top end. What Joe Rasmussen proposes however is to implement a Low pass filter. I will try the LPF in the final version.

joan2 · « **Reply #118 on:** Oct 15, 2003 at 11:23 AM »

to implement a lowpass filter with the gainclone is easy, you can put a small capacitor accross the feedback resirtor, the one from output terminal to the inverting terminal, this will roll-off the response at hf somewhat, you can start with a 0.0056uf cap...

Garp · « **Reply #119 on:** Oct 15, 2003 at 12:18 PM »

Thanks for the tip Joan2. When you say 'across,' is that the same as bypassing the feedback resistor with the small cap? Would mylar be ok to use?