Gainclone-chip amp?

heiney9 · June 2009

Let's have a discussion about pro's and con's of some of the most popular DIY gainclone/chip amps.

I see several DIY units FS and wonder how much of a difference a dedicated 300 va torroid w/ 4 large PS caps are used instead of a wall wart.

Looking to run a gain clone DIY with a simple tube pre amp for an alternative office rig. I sort of dismissed them when originally became popular now I need some info.

Thanks

H9

ShinAce · June 2009

Those chips have a decent PSSR, which means they reject hum. A traditional power supply will work just fine.

Where are you going to find a 200VA+ wall wart to power the amp?

strider · June 2009

heiney9 wrote: »

I see several DIY units FS and wonder how much of a difference a dedicated 300 va torroid w/ 4 large PS caps are used instead of a wall wart.

Thanks

H9

ShinAce wrote: »

Where are you going to find a 200VA+ wall wart to power the amp?

Agreed.

Why don't you build one yourself, Brock? There's a great deal of support out there, even if you've never tried I'd imagine you could produce something pretty decent.

Have you checked out 41hz.com?

heiney9 · June 2009

My question about the wall wart is that I remember the T-sonic coming with a wall wart and that possibly being a shortcoming. The unit I'm thinking about has 300va Torrid and 4 large bypass caps in a seperate case enclosure from the actual amp parts.

H9

megasat16 · June 2009

If I am right what you are thinking, it is LM3886 based amps you are talking about?

If you are going to use 4 large filter caps with the 300W toroid, I think eBay is a good source of toroid. I bought two 550W toroids with 37-0-37 for about $25 each.

I think 4 large filter caps should have enough reserve to run LM3886 to it's rated power under full load. But how large of the cap you are thinking?

zingo · June 2009

Chipamp.com has a few kits I've been looking into, from boards to power supplies.

heiney9 · June 2009

I have been so impressed with the Dared MP-5 clone, hybrid tube integrated with it's chip amp that I'm seriously thinking about buying a Rawsonte built unit or attempting a DIY. I have no equipment to measure anything, but if I could source all the parts and put it together like Lego's that would be cool.

H9

megasat16 · June 2009

I think GV has one of these chipamps so I think he'll chime in when he sees your post.

As far as building one, it should be relatively simple and parts are abundant. But building one might be more expensive than buying one on Agon. But getting a good time building it worth every penny of the extra expenses.

CoolJazz · June 2009

Interesting you should ask today this "how power supplies effect the sound" question. I was experimenting with this just last night!

I am working with a new active line-level crossover. The design only uses a single high quality op-amp in the high pass side. IE...not much in current draw. On hand, just for comparison of the effect of the power supply, are two very different supplies. One is a large, high output capable, wall wart. Looks like and may be one that the phone company used to supply some of the wall packs. The second is a hand made choke input, shunt regulated dual supply. Dual as in seperate supplies for left and right channels. So by changing a single plug, I could swap between supplies for the crossover. Also, the crossover itself has plenty of local capacitance via high quality Blackgates. They should greatly reduce the sonics dependancy on the quality of the power supply, right?

So what I noticed was that as I changed between supplies, still on the floor between the speakers and out of prime listening position, was that the lower grade supply had a slightly difference hardness to the music. Then on closer comparison you could identify the depth of the stage as being greater on the better supply. The ring of a tambourine being shook as being more real and less just of a metalic only effect on the shakers. (Song referred to here is the beginning of cut #3 on Jazz at the Pawnshop.)

I flipped back and forth several times and felt the difference always remained there. So I convinced myself that you definitely get a sonicly different result depending on power supply quality, even in low current draw situations. :cool:
CoolJazz

heiney9 · June 2009

A little off subject................but it's my thread

Yeah, I'm not a big fan of the switching power supply wall warts. I found a guy Aric Audio that builds high quality low cost tube pre amps but all his PS are switching type wall warts and I'm leary of that. Granted for the cost of most of his stuff adding a dedicated PS would probably add a fair amount of cost..............my biggest concern is how much sacrafice to the sound is one making buying a tube pre like this vs. one with a dedicated PS.

Thought about buying the Aric Audio 2.6 and mating to a nice Gain Clone amp for an alternative office rig over my Dared MP-5.

Really wanted to put something together for about $350. Just bouncing some idea's around.

H9

P.s. Keep the thoughts coming

heiney9 · June 2009

CoolJazz it makes perfect sense as the power supply section is just as important as anything else in the design. Since this will be for a alternate secondary system I'm willing to make a little bit of sacrafice in some area's.

H9

megasat16 · June 2009

I just came across one in Agon. Looks like a decent one.

But building one would be more fun.

http://www.audiogon.com/cgi-bin/cls.pl?ampstran&1251077847&/gainclone-heavy-duty

A Good Power Supply section is a very basic building block to determine how an amp or a preamp will sounds. That's where cheap stuff usually cuts corner with lower quality parts. A good low noise Plitron Audio Transformer cost nearly 2-4 times more than regular toroid from other manufacturer. I also think the audio transformer should be encapsulated in some kind of shielding in a good amp design.

heiney9 · June 2009

megasat16 wrote: »

I just came across one in Agon. Looks like a decent one.

But building one would be more fun.

http://www.audiogon.com/cgi-bin/cls.pl?ampstran&1251077847&/gainclone-heavy-duty

A Good Power Supply section is a very basic building block to determine how an amp or a preamp will sounds. That's where cheap stuff usually cuts corner with lower quality parts. A good low noise Plitron Audio Transformer cost nearly 2-4 times more than regular toroid from other manufacturer. I also think the audio transformer should be encapsulated in some kind of shielding in a good amp design.

Yep, I was trying not to post the link so as to have someone buy it from under me. That in fact is the link I was talking about, but sometime earlier this A.M. he switched the ad to the current amp. I'm guessing he sold the amp I was interested in but kept the same Audiogon ad to post the current amp.

The one pictured now is not the one I was talking about in this thread. Still I'm sure it's a great amp. The other one was called a "little bug" was cooler looking and much smaller with a seperate case housing the torrid and filter caps.

H9

megasat16 · June 2009

heiney9 wrote: »

Yep, I was trying not to post the link so as to have someone buy it from under me.

H9

Oops...Sorry about that.

heiney9 wrote: »

The other one was called a "little bug" was cooler looking and much smaller with a seperate case housing the torrid and filter caps.
H9

The one with separate transformer housing could be beneficial from any transformer related noises.

May be DIY is calling your name!

This toroid may worth take a look.

http://cgi.ebay.com/AMVECO-Toroidal-Transformer-TRF-AA-29728B-NEW-438VA_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a2Q7c39Q3a1Q7c72Q3a1234Q7c240Q3a1318Q7c301Q3a0Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem53db7e0c1bQQitemZ360164756507QQptZBIQ5fCircuitQ5fBreakersQ5fTransformersQQsalenotsupported

ShinAce · June 2009

Where's GV? I know he has a few of these amps and has them running (highs?).

Zingo, didn't you do a gainclone too?

I think Ben6270(some number) played with a few of these guys, or considered it.

If you need help with the power supply, keep asking questions. A lot of people here can help you out, including myself. I have to admit, I like to overfilter my supplies, and I know this is for a second rig.

Systems · June 2009

CoolJazz wrote: »

So I convinced myself that you definitely get a sonicly different result depending on power supply quality, even in low current draw situations. :cool:
CoolJazz

I agree that power supply quality is very important.A number of years ago W Jung did series of articles about voltage regulation that was rather interesting and gave clear evidence that not all regulators are created equal.Since then I have only used high performance discrete type regulators (ie Sulzers) for my opamp based projects.Discrete regs are not as compact and easy to use but definately outperform the cheap 3 pin LM78/79 family of IC regulators.I am currently in the process of installing a pair of Sulzers to retrofit into my DAC.

ben62670 · June 2009

I did a few. I liked them a lot. I used the "deal of the century" amp PS, and was very impressed. This was with cheap caps, and R's. I used Brian's boards(chipamp.com), and it was like paint by number.

Edit:

megasat16 wrote: »

...
I bought two 550W toroids with 37-0-37 for about $25 each...

28vac is the highest you want to run. After rectification you are pushing the max real close.

Systems · June 2009

ShinAce wrote: »

Where's GV? I know he has a few of these amps and has them running (highs?).

Yeah I have a couple of them, here's one. http://www.polkaudio.com/forums/index.php

The other runs my computer rig.

Thanks Ben

ben62670 · June 2009

http://www.polkaudio.com/forums/showthread.php?t=70352
Here is my project. I was able to pull around 100w sine waved in decent burst. I was doing this as a sacrificial test, but I think they lived!

Edit:GV linky no work.

megasat16 · June 2009

megasat16 wrote: »

I think eBay is a good source of toroid. I bought two 550W toroids with 37-0-37 for about $25 each.

ben62670 wrote: »

Edit:

28vac is the highest you want to run. After rectification you are pushing the max real close.

Yeah Ben! I was just saying the toroids on eBay are Cheap. I know mine may not be suitable for the chipamps. But if you use LM3886, I think the max voltage is about 80V?

Anyway, the toroids I bought for different amp designs which I am playing with...I am not building a chip amp soon.

Edit : 84Vdc (which is about 42V each rails). So, the AC should be around 30V or less from the secondary if you use LM3886.

Systems · June 2009

Heres the working link. http://www.polkaudio.com/forums/showthread.php?t=71781&highlight=GAINCLONE+MAKEOVER

ShinAce · June 2009

megasat16 wrote: »

Yeah Ben! I was just saying the toroids on eBay are Cheap. I know mine may not be suitable for the chipamps. But if you use LM3886, I think the max voltage is about 80V?

Anyway, the toroids I bought for different amp designs which I am playing with...I am not building a chip amp soon.

Edit : 84Vdc (which is about 42V each rails). So, the AC should be around 30V or less from the secondary if you use LM3886.

The last time I looked at the LM3886T, I remember coming up with a 48VCT transformer as a good choice for 8 ohm bridged operation, and 36 VCT looked good for a 4 ohm load(bridged).

Systems · June 2009

ShinAce wrote: »

, and 36 VCT looked good for a 4 ohm load(bridged).

Yeah you would want to keep voltages down when driving 4 ohm loads because the small chip is not very good at disipating heat and will go into thermal protection if it gets to hot.

For operation into 4 ohm's paralleling 2 (or more)would be preferable to running them bridged.This will give a increase in current output plus the voltage on the rails can be raised somewhat. This because unlike in bridged mode the chips will be sharing the load so the heat will be disipated across 2(or more) chip bodies instead of one.This reduces the likelihood of the thermal protection always kicking in and improves long term reliability.

I recently purchased one of these on Ebay for a mere $22. http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=230351662075QQssPageNameZMERC_VIC_RCRX_Pr4_PcY_BIN_Stores_IT&refitem=230341570648&itemcount=4&refwidgetloc=closed_view_item&usedrule1=CrossSell_LogicX&refwidgettype=cross_promot_widget&_trksid=p284.m183&_trkparms=algo%3DCRX%26its%3DS%252BI%252BSS%26itu%3DISS%252BUCI%252BSI%26otn%3D4
Its a complete PC board with 3 x LM3886 in a parallel config.I did some testing and it gave me about 80 clean watts into 4 ohms with +-30 VDC rails.It will be powered by a 225VA toroid.

heiney9 · June 2009

What do you guys think about this as a starting point? It seems most of this stuff comes from the Pacific Rim. Good, bad, fake......discuss.

What type of transformer would I need?

http://cgi.ebay.com/NEW-LM833-LM3886-Amplifier-Board-Upgrade-Version_W0QQitemZ140328058984QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item20ac344068&_trksid=p3286.c0.m14&_trkparms=65%3A1|66%3A2|39%3A1|240%3A1318|301%3A0|293%3A4|294%3A50

or I really like the looks of this. I like the separate PS caps

http://cgi.ebay.com/NEW-LM3886TF-2X60W-Power-Amplifier-Board-DIY-1-2_W0QQitemZ140328059965QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item20ac34443d&_trksid=p3286.c0.m14&_trkparms=65%3A1|66%3A2|39%3A1|240%3A1318|301%3A0|293%3A4|294%3A50

H9

Systems · June 2009

I have been considering this one,it's similar to the one in your first link.http://cgi.ebay.ca/2-x-68W-Watt-LM3886-NE5532-Audio-Amplifier-Board_W0QQitemZ230351583864QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item35a2063a78&_trksid=p4634.c0.m14&_trkparms=%7C301%3A1%7C293%3A1%7C294%3A30 It also has the opamp input buffer but uses the better NE5532 vs the LM833.Ofcourse either of these can easily be upgrade to one of the better op amps from BB or AD.

Fakes are a real concern to be sure ,because of the seemingly impossible low price I was expecting the possibility of that being the case when I purchased my 3x LM3886 board from Hong Kong.I was happy to find that the LM3886's look and perform like the real deal.That most likely won't be the case with every Asian sourced Chip amp kit on Ebay.

Systems · June 2009

heiney9 wrote: »

.

What type of transformer would I need?

2x 22-25 volts with a mimimum wattage rating of about 160VA.

megasat16 · June 2009

heiney9 wrote: »

What do you guys think about this as a starting point? It seems most of this stuff comes from the Pacific Rim. Good, bad, fake......discuss.

H9

Buying from reputable eBay sellers from HongKong is all positive experiences for me so far. It takes 2-3 weeks for delivery (normal snail air mail) though.

heiney9 · June 2009

Thinking of going with this

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

to make this (towards the bottom)

http://diyaudioprojects.com/Chip/LM3886_CA/LM3886_CA.htm

Or I may just go with Zingo's suggestion of a Chipamp board and source my own components.........we'll see

Face · June 2009

Brock, looking for something that runs cooler in the summer?

heiney9 · June 2009

Face wrote: »

Brock, looking for something that runs cooler in the summer?

Nah, just looking to build and inexpensive alternate rig for the office. I am so damn impressed with the Dared MP-5 and it's gainclone output that I thought I'd tackle something with a tad more power.

I also have my eye on this as it's local so I can pick it up.(it's an older model)

http://www.shop.aricaudio.com/product.sc?categoryId=2&productId=13

Mate the gainclone and the Aric Audio pre might make a cool little rig. I dunno though, I don;t really need it............but you know how that goes.

H9

P.s. The Pass does really make for a HOT room especially if the air is off.

Systems · June 2009

heiney9 wrote: »

Thinking of going with this

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

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

Gainclone-chip amp?

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