Gainclone-chip amp?

heiney9 · June 2009

GV#27 wrote: »

Be aware that auction is for blank boards only.No components

Didn;t realize that especially after the description

this amplifier is used fiber glass PCB,.Excellent electrolytic capacitors、film capacitors and precision metal film resistors. it has on board DC power supply.just connect the power transformer and aluminum heatsink to run it.

Systems · June 2009

heiney9 wrote: »

Didn;t realize that especially after the description

this amplifier is used fiber glass PCB,.Excellent electrolytic capacitors、film capacitors and precision metal film resistors. it has on board DC power supply.just connect the power transformer and aluminum heatsink to run it.

Yeah the description makes it confusing.

If you decide to go the blank board route I have some 10,000uf filter caps if you need em.(freebies)

The Hammond case as shown in your second link work great for Gainclones.I'm using one for my paralleled 3886's board.

heiney9 · July 2009

I think I've pretty much decided on this because it seems to have "upgraded" parts in the Bennic caps:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=140330346347

I plan on replacing the PS caps with Panasonic's and at some point will replace the opamp's.

This is going to be a starter amp so I want something simple. I might consider putting the PS in a separate chassis just to keep things small.

Thought, comments, etc. I can buy the same thing from Chipamp.com for about $85. Would that be a better choice?

Thanks--H9

strider · July 2009

Personally, I'd be more comfortable buying from chipamp.com just due to the support from them vs someone from China. As I get some experience under my belt, then maybe I'll buy from elsewhere.

Not that there isn't a ton of info out there on gain clones out there

heiney9 · July 2009

Well I just bought this for my pre-amp for an office based rig with a DIY gainclone amp.

http://www.audiogon.com/cgi-bin/cls.pl?preatube&1251961925&/Dared-SL2000A-Linestage-preamp.

the SL-2000A is a very simply designed entry-level line stage preamp. The total gain is about 20dB.

Does the typical LM3886 kit as is from Chipamp.com need more that 20dB of gain? If it does how do I go about doing that? Will the gainclone be a good match for this type of pre-amp? I feel totally clueless here. I really don;t want to buy a Rawsonte, because I think I can do this but........the amp and pre have to work together.

H9

Systems · July 2009

deleted

mmadden28 · July 2009

GV#27 wrote: »

Yeah the description makes it confusing.

....

What is it about that ebay ad that made you think that? Only 1 negative feedback-I would expect more if that were common place. He got a positive on a previous sale for that same board

Systems · July 2009

mmadden28 wrote: »

What is it about that ebay ad that made you think that? Only 1 negative feedback-I would expect more if that were common place. He got a positive on a previous sale for that same board

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200357169266&fromMakeTrack=true&ssPageName=VIP:Watchlink:middle:us

Because the auction is for blank boards only, but the description at the bottom pertains to the complete unit which he also sells.

mmadden28 · July 2009

I guess I still don't see it. I don't see anything saying its a blank board and its in the 'amplifiers' category. He has another auction for a PCB board only and the pics show only a board and the description clearly states PCB only (except the pic of the completed board but it states that)-and its in the PCB category. I just don't get it-doesn't matter anyway-I was just curious. Sorry to derail...

Systems · July 2009

mmadden28 wrote: »

He has another auction for a PCB board only and the pics show only a board and the description clearly states PCB only (except the pic of the completed board but it states that)-and its in the PCB category.

If thats the case then I have it confused,that auction states it's a board so I took it to mean board only.The final sale price would indicate it's a complete unit. I've looked at a ton of these GC related amps/PCB's from Asia on ebay and have found that some vendors descriptions are lacking in clarity.

I apologize for the mix up.

heiney9 · July 2009

GV#27 wrote: »

If thats the case then I have it confused,that auction states it's a board so I took it to mean board only.The final sale price would indicate it's a complete unit. I've looked at a ton of these GC related amps/PCB's from Asia on ebay and have found that some vendors descriptions are lacking in clarity.

I apologize for the mix up.

I think that's why I'm just going to get the kit from Chipamp.com. Probably worth the extra money, plus I know exactly what parts I'm getting.

I read thru the tutorial at chipamp.com and what "other" equipment will I need? Am I going to have to make measurements before I power it up? The biggest area I'm worried about it the PS and it's associated connections, especially proper grounding.

I really want to do this, but at the same time I'm apprehensive because all my knowledge is "book" knowledge and it's been years since I've even tinkered inside any of this stuff.

I have a mostly dead Luxman R113 with a beautiful potted transformer. How would I know if the tranny would be compatible for my DIY build. It's a 30wpc receiver.

H9

mmadden28 · July 2009

I hear ya, you really do have to super-analyze the ads though-they can be quite crafty-I figure if the seller does it often then his feedback will reflect the disappointments. I remember not too long ago one seller was selling a vintage stereo, when it was just the box and styro.
Just wanted to make sure we weren't missing some red flag.

mmadden28 · July 2009

heiney9 wrote: »

...Am I going to have to make measurements before I power it up? The biggest area I'm worried about it the PS and it's associated connections, especially proper grounding.
...
H9

What tools do you have? Do you at least have a multimeter?

heiney9 · July 2009

mmadden28 wrote: »

What tools do you have? Do you at least have a multimeter?

At this point I have nothing, not even a soldering iron. I'm not opposed to getting a MM, should have one anyway. My concern is spending a lot of time making measurements and trying to run down problems. I am a novice and this project appeals to me because of it's simplicity. I'm more jazzed about coming up with a cool design for the case.

I still have a lot or research to do to properly understand the PS section. Dangerous voltages and I don;t want to blow anything up because then the cost effectiveness goes out the window if I have to start replacing parts I ruined, etc.

megasat16 · July 2009

heiney9 wrote: »

At this point I have nothing, not even a soldering iron. I'm not opposed to getting a MM, should have one anyway. My concern is spending a lot of time making measurements and trying to run down problems. I am a novice and this project appeals to me because of it's simplicity. I'm more jazzed about coming up with a cool design for the case.

I still have a lot or research to do to properly understand the PS section. Dangerous voltages and I don;t want to blow anything up because then the cost effectiveness goes out the window if I have to start replacing parts I ruined, etc.

I think Ben had post a link to the cheap soldering gun on PE.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=374-100

But if you are going to use the soldering gun more frequently, I would buy a more expensive and feature rich gun.

This is what I bought a year ago and I am quite happy with the quality of it. I also bought a few different tips for different jobs.

http://cgi.ebay.com/Soldering-Iron-Station-digital-TMC-08-1000D-free-solder_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a2Q7c39Q3a1Q7c72Q3a1205Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem1e571efa73QQitemZ130310666867QQptZLHQ5fDefaultDomainQ5f0QQsalenotsupported

You should also invest in a good solder sucker and a solder wick and a small case of solder flux and a good solder.

http://www.parts-express.com/wizards/searchResults.cfm?srchExt=CAT&srchCat=361&CFID=3283963&CFTOKEN=17715912

For once in a lifetime investment of DMM, I would get one from Fluke. But if you are on budget, look at the auto-ranging DMM from RatShack, they are also reasonable around $30-$40.

megasat16 · July 2009

heiney9 wrote: »

I have a mostly dead Luxman R113 with a beautiful potted transformer. How would I know if the tranny would be compatible for my DIY build. It's a 30wpc receiver.

H9

You need to find out what's the voltage coming out from the secondary from the transformer. You need to measure with DMM in AC range from.

I think you need transformer with 25-29V (max) secondaries. I think you need center tapped transformer with something like 25V-0-25V.

megasat16 · July 2009

megasat16 wrote: »

You need to find out what's the voltage coming out from the secondary from the transformer. You need to measure with DMM in AC range from.

Incomplete sentence above....

I mean AC range from 200V or below settings or use an auto-ranging DMM.

Also, do not worry about blowing up a thing or two in the beginning building stage. It'll help you understand and dig deeper into why you blew it up. As long as it's not lethal or putting yourself in the danger or electrocution, it's a good learning experiences for the beginner.

heiney9 · July 2009

Thanks for the help so far.

I'm going with the Chipamp LM3886 Stereo Kit. I'll be driving a pair of 5B's (6 ohm nominal) in a smaller room. Will this torrid be a good choice or should the load capacity be higher than 250VA and is the 2ndary voltage ok? Should it be higher or lower?

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=122-625

I did read anything higher than 160VA up to 300VA and 2ndary voltage in the range of 18-25v is a good choice.

Give me some input. Once I get the tanny figured out, I'm half way there.

H9

megasat16 · July 2009

I would get 200W minimum and 300W if possible. You can always reuse the bigger toriod for other amps later. If you use bigger toroid, you may need to use higher current Bridge Rectifier / Diode in the PS circuit than it's designed for. But usually, designer covers tolerances for transformer and use high current fast recovery full wave bridge rectifiers (diodes) so you will be OK.

I will look around some suitable toroids on the Bay and post a link if I found something. I hope GV can chime in since he is quite resourceful. He hooked me up with his pal Jim for Pass clones PCB.

http://cgi.ebay.com/Toroidal-Power-Transformer-Amveco-Magnetics-AA25710B_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a2Q7c39Q3a1Q7c72Q3a1205Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem2c4fed6daaQQitemZ190319521194QQptZBIQ5fCircuitQ5fBreakersQ5fTransformersQQsalenotsupported

heiney9 · July 2009

Thanks Mega!

If I buy a new Torrid I've decided to go with this. Your suggestion reinforces this choice as does the gainclone build thread on DIYAUDIO.com

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=122-640

My biggest concern is getting the PS section hooked up properly and taking the measurements to ensure all is well from the PS section.

megasat16 · July 2009

I think what PE offers is a good toroid but the toroid on eBay is cheaper and will do the same except it is more powerful and cheaper than the PE one. But going with what others has done is better in your case.

For the PS section, you just need to assemble it and test the output from the cap banks for DC. If you do it right, DC should be around +34V and -34V if using the 25-0-25 toroid.

AC coming out from the PS section should be very small and unmeasurable (at least in the very few milli-volts and will not be accurate with el cheapo DMM).

Just make sure you have an appropriate fuse (about 120V, 3A slow blow or time delay) inline in the AC line before the toroid.

heiney9 · July 2009

megasat16 wrote: »

I would get 200W minimum and 300W if possible. You can always reuse the bigger toriod for other amps later. If you use bigger toroid, you may need to use higher current Bridge Rectifier / Diode in the PS circuit than it's designed for. But usually, designer covers tolerances for transformer and use high current fast recovery full wave bridge rectifiers (diodes) so you will be OK.

I will look around some suitable toroids on the Bay and post a link if I found something. I hope GV can chime in since he is quite resourceful. He hooked me up with his pal Jim for Pass clones PCB.

http://cgi.ebay.com/Toroidal-Power-Transformer-Amveco-Magnetics-AA25710B_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a2Q7c39Q3a1Q7c72Q3a1205Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem2c4fed6daaQQitemZ190319521194QQptZBIQ5fCircuitQ5fBreakersQ5fTransformersQQsalenotsupported

If I get a torrid over 300Va will I need or is it recommended to have a soft start circuit. Been doing a lot of research and this seems to be what some recommend. Really want to keep it ultra simple so I'd prefer not to have a soft start.

H9

megasat16 · July 2009

Yes! You should use 330W toroid from PE.

I doubt using larger toroid will need a soft start for it but by all means, I am not expert in the chipamp application and I have not build one either so I can't make a very useful comment for it. On the contrary, GV has built one (many) so I think he'll chime in soon. I remember him saying that he use +30V and -30V rails but I don't know what size toroid he uses.

Any impact of using larger toroid needs to be studied by building one myself and learning the chipamp design and chipamp built in protection before I could make further comment on it.

I don't want to provide the half right and half wrong information to you and makes you hell of frustrated.

I've ordered two of the 550W transformers for my own use (cost like $20 each and $22.50 shipping for two). I have a lot of build projects going on so it'll be a while before I figure out what changes are required if higher power toroid is used.

megasat16 · July 2009

The Two Toroids I bought from Fleabay are in today. They looks dusty and dirty but comes out nicely after a clean wipe with damp cloth. I need to test these over the weekend.

Did you get your chipamp parts and started on the project?

heiney9 · July 2009

More questions.

Snubberized vs. non-snuberized power supply board?

What's the difference and why one over the other, which is better for sound?

I've seen kits with both and it seems many of the DIY gainclones FS don't have a snubber power supply.

Help me understand and quickly because I have a line on a nice DIY gainclone but it uses a non-snubber PS.

TIA

H9

megasat16 · July 2009

Oh hell...You got me...:D What is a snubber?

I don't think snubber is needed but a snubber is an RC network or something like that to smooth out transients in the power section. There is a thread on DIYAudio.com about it.

I don't know whether it's needed or not for GC amp but I will just build full regulated DC power Supply for it and forget about the snubber.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=43423

heiney9 · July 2009

Lost my motivation and have no extra time at the moment so I got a great deal on this:

http://www.audiogon.com/cgi-bin/cls.pl?ampstran&1253218507&/Gainclone-LM3875-Stereo-Amp

I couldn't make it cheaper than I bought this for. I like the layout and he used Caddock and Riken resistors and Black Gate caps.

I know I sort of whimped out by not building it myself, but there are still room for improvements on this one.

H9

cnh · July 2009

I can't say I understand most of what is going on 'above' but I'm sure this thread will prove invaluable for others with more knowledge about amp designs...and if I ever decide to get adventurous enough and buy a few books on such topics perhaps it will even be something I return to...although, I have so many other things to read that I doubt I have the 'time' to delve into such a field in any depth.

But it is interesting trying to follow the above...

I can't wait to see or hear the review of the finished products..

Good luck guys..

cnh

heiney9 · July 2009

cnh wrote: »

I can't say I understand most of what is going on 'above' but I'm sure this thread will prove invaluable for others with more knowledge about amp designs...and if I ever decide to get adventurous enough and buy a few books on such topics perhaps it will even be something I return to...although, I have so many other things to read that I doubt I have the 'time' to delve into such a field in any depth.

But it is interesting trying to follow the above...

I can't wait to see or hear the review of the finished products..

Good luck guys..

cnh

The Gainclone is about as basic of an amp as you can get. Simple, simple, simple. Only 9 parts plus a power supply. I just don;t have time right at the moment and I have no "extra" spare parts laying around like some of the other DIYer's do. So I'd have to buy the chassis, power switch, fuseable link, IEC connector, input/output terminals, LED, heatsinks, wire, solder, etc, etc. Costs really started to add up for all the additional parts to assemble the entire amp.

I highly recommend trying to build it and so far the Gainclone's I;ve heard sound really good (excellent in one case) with efficient speakers. I have a tubed pre I'm going to run this with and a pair of modded Polk Moniter 5B's.

H9

strider · July 2009

heiney9 wrote: »

Lost my motivation and have no extra time at the moment so I got a great deal on this:

http://www.audiogon.com/cgi-bin/cls.pl?ampstran&1253218507&/Gainclone-LM3875-Stereo-Amp

I couldn't make it cheaper than I bought this for. I like the layout and he used Caddock and Riken resistors and Black Gate caps.

I know I sort of whimped out by not building it myself, but there are still room for improvements on this one.

H9

Don't feel too bad, I've got parts for three chip amps plus an F5 clone sitting in boxes at my house.

You got a good deal to boot.

Gainclone-chip amp?

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