Gainclone/card the hard numbers, where are the specifications?

Jacobus · 27th February 2005, 09:30 AM

Hi all,

I'm thinking of builing a gainclone amp. A lot of people saying good things about them....but, they only do it by ear. I would like to see first some hard numbers before I start to see if it is worth to invest my time and money into it. (THD, noise, freq. range within *dB etc etc etc)

So...who can point me to sites that actually measure the equiptment instead of just some subjectively listening test.

Cheers,

Jacob

random_id · 27th February 2005, 01:06 PM

I would try THIS as well as looking at the specs for the chip itself.

For me, I couldn't tell you the specs for my amp, because I have no clue how to test it. I think that is part of the magic of the chipamp. You have individuals who are reinventing the wheel everyday with T-network feedback, input buffers, and regulated, then snubbed power supplies. You also have people like me who is lucky if I can sort out the capacitors from the other round things...I think they are called resistors.

Anyhow, another reason for limited specs is the amount of diversity in design. It seems that there is a huge difference between each gainclone with respect to case, heatsink, length/insolation of wires, etc. that would affect specs from one amp to the next.

I hope you find the numbers you are looking for. Look at it this way, if it is half as good as everyone says, its still a heck of a bargin to build and use.

Jacobus · 27th February 2005, 04:29 PM

Thanks for the site ! I have found some info about THD, but a good THD alone does not make already a good amp. I'm still looking for other specifications like freq flatness, noise, hiss levels. I can understand that it is difficult to measure these specs for DIY (by the way I don't agree that wire, casing, heatsink etc. will have any influence on the mentioned parameters.) But I'm shocked that even 47labs doesn't give these specs for something that costs several 1000euro !!!!!!!! I'm sure they have the means to measure it. And if they don't they are frauds. I would already be happy with the specs of the ori. gaincard, if these are good that I'm sure the specs. of a gainclone will also be good.

cheers,

Jacob

Netlist · 27th February 2005, 04:44 PM

If external factors like case, wire, connectors...have no influence you might as well take a look at the datasheet.
A properly build gainclone will certanly meet those specs.
A state of the art-build exemplare might outperform it but there's no garantie that you will be able to measure it IMHO.
Some say they can hear the difference between different materials used in gainclones. That is again wires, connectors etc...
I'll never argue about that because I'm sure my ears are not good enough to tell.

/Hugo

GregGC · 27th February 2005, 04:49 PM

Look here:
http://cache.national.com/ds/LM/LM3875.pdf
The original gaincard is based on this chip.
That spec sheet will give you all the parameters you need to know about the possibilities when using that chip.

50W
0-200kHz (gain 26dB)
98-122dB noise
0.01 THD

Happy DIYing
Greg

random_id · 27th February 2005, 07:41 PM

I agree with you that the choice of heatsink is probably not going to drastically alter THD. However, there was that long time discussion about ringing with finned heatsinks.

What I was implying is that short, thick, well-insulated wires with a seperate PS may have better specs with regards to noise than an all-in-one bird's nest of wires.

The THD and other info can be gotten from National's site like other people have suggested. Here is the link for the LM3886 (here ).

Steve Eddy · 27th February 2005, 08:27 PM

Robert Deutsch reviewd the 47 Labs Gaincard in the December, 2001 issue of Stereophile and John Atkinson did is usual suite of measurements.

Here's the review: 47 Labs 4796 Gaincard power amplifier

Here's the measurements: Sidebar 3: Measurements

se

Jacobus · 28th February 2005, 08:49 AM

Hey guys,

Thanks for all the tips and links ! The gainclone looks really interesting to build, it is cheap, appears to be very good and is easy to build. The only problem is connecting my Turntable, so I would need a good phonostage for that, pref. DIY also, and again cheap but good. any suggestions?

DonoMan · 28th February 2005, 12:02 PM

If you want to keep it simple, you could use an OPA2134, OPA2227, or a couple of OPA627s

Hugh M · 28th February 2005, 01:03 PM

Try here for a simple straight forward phono stage DIY phono preamp - cheap and simple!
A good read thru this thread should give you all the info you need.
I built this and it sounds quite good to me and I still have to get some better caps for the riaa stage.
Hugh

27th February 2005, 09:30 AM	#1
Jacobus diyAudio Member Join Date: Feb 2005 Location: Maastricht, the Netherlands	Gainclone/card the hard numbers, where are the specifications? Hi all, I'm thinking of builing a gainclone amp. A lot of people saying good things about them....but, they only do it by ear. I would like to see first some hard numbers before I start to see if it is worth to invest my time and money into it. (THD, noise, freq. range within *dB etc etc etc) So...who can point me to sites that actually measure the equiptment instead of just some subjectively listening test. Cheers, Jacob

28th February 2005, 08:49 AM	#8
Jacobus diyAudio Member Join Date: Feb 2005 Location: Maastricht, the Netherlands	connecting my phono to it Hey guys, Thanks for all the tips and links ! The gainclone looks really interesting to build, it is cheap, appears to be very good and is easy to build. The only problem is connecting my Turntable, so I would need a good phonostage for that, pref. DIY also, and again cheap but good. any suggestions?

28th February 2005, 01:03 PM	#10
Hugh M diyAudio Member Join Date: Sep 2004 Location: Saint John NB	Try here for a simple straight forward phono stage DIY phono preamp - cheap and simple! A good read thru this thread should give you all the info you need. I built this and it sounds quite good to me and I still have to get some better caps for the riaa stage. Hugh __________________ Lots of Fun and Good sound too - Who could ask for more?

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27th February 2005, 01:06 PM	#2
random_id diyAudio Member Join Date: Feb 2004 Location: PA	I would try THIS as well as looking at the specs for the chip itself. For me, I couldn't tell you the specs for my amp, because I have no clue how to test it. I think that is part of the magic of the chipamp. You have individuals who are reinventing the wheel everyday with T-network feedback, input buffers, and regulated, then snubbed power supplies. You also have people like me who is lucky if I can sort out the capacitors from the other round things...I think they are called resistors. Anyhow, another reason for limited specs is the amount of diversity in design. It seems that there is a huge difference between each gainclone with respect to case, heatsink, length/insolation of wires, etc. that would affect specs from one amp to the next. I hope you find the numbers you are looking for. Look at it this way, if it is half as good as everyone says, its still a heck of a bargin to build and use.

27th February 2005, 04:29 PM	#3
Jacobus diyAudio Member Join Date: Feb 2005 Location: Maastricht, the Netherlands	Thanks for the site ! I have found some info about THD, but a good THD alone does not make already a good amp. I'm still looking for other specifications like freq flatness, noise, hiss levels. I can understand that it is difficult to measure these specs for DIY (by the way I don't agree that wire, casing, heatsink etc. will have any influence on the mentioned parameters.) But I'm shocked that even 47labs doesn't give these specs for something that costs several 1000euro !!!!!!!! I'm sure they have the means to measure it. And if they don't they are frauds. I would already be happy with the specs of the ori. gaincard, if these are good that I'm sure the specs. of a gainclone will also be good. cheers, Jacob

27th February 2005, 04:44 PM	#4
Netlist diyAudio Moderator Join Date: Jan 2003	If external factors like case, wire, connectors...have no influence you might as well take a look at the datasheet. A properly build gainclone will certanly meet those specs. A state of the art-build exemplare might outperform it but there's no garantie that you will be able to measure it IMHO. Some say they can hear the difference between different materials used in gainclones. That is again wires, connectors etc... I'll never argue about that because I'm sure my ears are not good enough to tell. /Hugo

27th February 2005, 04:49 PM	#5
GregGC diyAudio Member Join Date: Oct 2003 Location: Toronto	Look here: http://cache.national.com/ds/LM/LM3875.pdf The original gaincard is based on this chip. That spec sheet will give you all the parameters you need to know about the possibilities when using that chip. 50W 0-200kHz (gain 26dB) 98-122dB noise 0.01 THD Happy DIYing Greg

27th February 2005, 07:41 PM	#6
random_id diyAudio Member Join Date: Feb 2004 Location: PA	I agree with you that the choice of heatsink is probably not going to drastically alter THD. However, there was that long time discussion about ringing with finned heatsinks. What I was implying is that short, thick, well-insulated wires with a seperate PS may have better specs with regards to noise than an all-in-one bird's nest of wires. The THD and other info can be gotten from National's site like other people have suggested. Here is the link for the LM3886 (here ).

27th February 2005, 08:27 PM	#7
Steve Eddy diyAudio Member Join Date: Sep 2002 Location: Sacramento, CA	Robert Deutsch reviewd the 47 Labs Gaincard in the December, 2001 issue of Stereophile and John Atkinson did is usual suite of measurements. Here's the review: 47 Labs 4796 Gaincard power amplifier Here's the measurements: Sidebar 3: Measurements se

28th February 2005, 12:02 PM	#9
DonoMan diyAudio Member Join Date: Feb 2005 Location: Massachusetts	If you want to keep it simple, you could use an OPA2134, OPA2227, or a couple of OPA627s

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