Hi folks, I`ve been browsing this forum for the last few weeks, trying to decide on which LM3875 based circuit to build as my first Gainclone. I know there will be no definitive answer to this question, but I`d like a little help in choosing which circuit to go for.
I currently have a (heavily modified !) NAD C521 CD player, Mission M73i speakers. I listen mainly to rock music.
I have the LM3875s, connectors, 1000ufs a few resistors etc. I just need to order the transformer(s).
1. Do I build an Inverting or Non-Inverting circuit ?
2. Do I use 1 big (300VA) or 2 small (160VA) transformers and are 18v secondaries "the best bet" ?
Any general advice would be most welcome, I`m good at soldering, but bad at making decisions !
I currently have a (heavily modified !) NAD C521 CD player, Mission M73i speakers. I listen mainly to rock music.
I have the LM3875s, connectors, 1000ufs a few resistors etc. I just need to order the transformer(s).
1. Do I build an Inverting or Non-Inverting circuit ?
2. Do I use 1 big (300VA) or 2 small (160VA) transformers and are 18v secondaries "the best bet" ?
Any general advice would be most welcome, I`m good at soldering, but bad at making decisions !
Go for invertingProf said:
I'm using dual 160VA transformers - personally think that this is the way to go. Dual PSU's makes it easier to avoid earth loops and hum problems.Prof said:
Some people have expressed a preference for 18V transformers, and if your speakers are efficient, then perhaps this would be the safest bet. But as my speakers 83dB/W, I went for 25V. My initial experiments were with a single 18V 120VA transformer - I didn't notice any bad effects when I upgraded to the 25V models.
If you haven't already done so, check my WWW and also Nuuk's. As well as the GainClone info, both these pages have lots of links to other GainClone site on the web.
Hope this helps,
Mark
Looks like it will be dual transformers
Thanks for the advice.
Today, I ordered 1 x 160VA 18+18V toroid. I`ll prototype and test 1st, then I`ll invest in another transformer. My speakers are quite efficient, so I think 18v will be the right choice.
The "tweaker" in me will mean that I`ll end up trying both inverting and non-inverting modes, and I`ll probably end up "fiddling" with the circuitry until I get it right. I can`t wait to hear what all the fuss is about, I just hope I`m not dissapointed !
I`ll post the results in the next few days.
Thanks for the advice.
Today, I ordered 1 x 160VA 18+18V toroid. I`ll prototype and test 1st, then I`ll invest in another transformer. My speakers are quite efficient, so I think 18v will be the right choice.
The "tweaker" in me will mean that I`ll end up trying both inverting and non-inverting modes, and I`ll probably end up "fiddling" with the circuitry until I get it right. I can`t wait to hear what all the fuss is about, I just hope I`m not dissapointed !
I`ll post the results in the next few days.
The route I took was :
www.diyaudio.com/forums/attachment.php?s=&postid=163274
I had to add a 0.1uf 100v between pins 1 & 4 (on some circuits this is a 1uf electrolytic) This cured a slight distortion problem. I didn`t use the 4.7uf Black Gate N as my CD player has no DC on it`s output. The input pot I`m using is a 100k LIN. The resistors are 1/8watt carbon, but I will try metal film, just to see if this makes any difference. The 1000ufs are reasonable quality rubycons (35v, 105 degree). I am using an 18 + 18v 160VA transformer, now I know this gainclone is good, I`m going to build another power supply to run each channel separately.
Results ? I`m very impressed, I`m no HI-FI expert, but it sounds quite a lot better than my NAD C350, which is supposed to be a decent quality amp (cost £300). The sound is clearer and more lively than the NAD. I will build my Gainclone into a case and replace the NAD with it !
www.diyaudio.com/forums/attachment.php?s=&postid=163274
I had to add a 0.1uf 100v between pins 1 & 4 (on some circuits this is a 1uf electrolytic) This cured a slight distortion problem. I didn`t use the 4.7uf Black Gate N as my CD player has no DC on it`s output. The input pot I`m using is a 100k LIN. The resistors are 1/8watt carbon, but I will try metal film, just to see if this makes any difference. The 1000ufs are reasonable quality rubycons (35v, 105 degree). I am using an 18 + 18v 160VA transformer, now I know this gainclone is good, I`m going to build another power supply to run each channel separately.
Results ? I`m very impressed, I`m no HI-FI expert, but it sounds quite a lot better than my NAD C350, which is supposed to be a decent quality amp (cost £300). The sound is clearer and more lively than the NAD. I will build my Gainclone into a case and replace the NAD with it !
NAD NOT
Thanks. I also have an NAD (2400) power amp and I have always liked it. From your experience It sounds like after I finish my gainclones the NAD might have to move to the center channel
What is the sensitivity of the speakers that you used with your gainclone? I was just trying to decide between 18v and 22v toroids as this is the most expensive part (my B&W CDM7 SE are 90db.)
Its nice to know another NAD user liked the gain clone.
Thanks. I also have an NAD (2400) power amp and I have always liked it. From your experience It sounds like after I finish my gainclones the NAD might have to move to the center channel
What is the sensitivity of the speakers that you used with your gainclone? I was just trying to decide between 18v and 22v toroids as this is the most expensive part (my B&W CDM7 SE are 90db.)
Its nice to know another NAD user liked the gain clone.
Better than NAD ?
Hello Joe,
Well, I`ve only been running my new Gainclone for a day or two, but from memory, it is producing better noises than my "proper" amplifier. I will connect the NAD back up in the next day or so, that will be an interesting test. I think the NAD will sound very "flat" after the Gainclone. My gainclone just sounds so clear and detailed, I`m sure you`ll get the similar results. Let me know how it goes.
Hello Joe,
Well, I`ve only been running my new Gainclone for a day or two, but from memory, it is producing better noises than my "proper" amplifier. I will connect the NAD back up in the next day or so, that will be an interesting test. I think the NAD will sound very "flat" after the Gainclone. My gainclone just sounds so clear and detailed, I`m sure you`ll get the similar results. Let me know how it goes.
NADS!
Last year I tried a NAD 3225PE - the PCB silkscreen has "3020/3225PE" marked on it because it's a 3020 with extra optional bits installed that boost the supply rails during transients. (Not Class G)
I was shocked at how it sounded. A dull, flat and undetailed sound with flabby bass. Being positive, you could say that it was "polite" - it was quite pleasant for quiet backround musak
Given the rave reviews, this was a bit of a surprise. Does anyone know how the 3020/3225PE compares with the newer NADs? As far as I can tell, they are using a similar circuit, but with newer components?
This was compared to the Musical Fidelity A1 that I was using at the time. Given that my GainGlone is a step up from that, I reckon you'll have no problem hearing the improvment
Cheers,
Mark
Last year I tried a NAD 3225PE - the PCB silkscreen has "3020/3225PE" marked on it because it's a 3020 with extra optional bits installed that boost the supply rails during transients. (Not Class G)
I was shocked at how it sounded. A dull, flat and undetailed sound with flabby bass. Being positive, you could say that it was "polite" - it was quite pleasant for quiet backround musak
Given the rave reviews, this was a bit of a surprise. Does anyone know how the 3020/3225PE compares with the newer NADs? As far as I can tell, they are using a similar circuit, but with newer components?
This was compared to the Musical Fidelity A1 that I was using at the time. Given that my GainGlone is a step up from that, I reckon you'll have no problem hearing the improvment
Cheers,
Mark
Just do it, JOE!
It seams there are many NAD users around here.
I have an old NAD Monitor Series 7000 receiver (for those who remember the Monitor Series, from around 1990).
My NAD is heavily tweaked and sounds much better than in original form.
I love it's sound.
But when I made my GC I was astonished.
Let's just say the Nad goes to the basement.
JOE DIRT® said:
It seams there are many NAD users around here.
I have an old NAD Monitor Series 7000 receiver (for those who remember the Monitor Series, from around 1990).
My NAD is heavily tweaked and sounds much better than in original form.
I love it's sound.
But when I made my GC I was astonished.
Let's just say the Nad goes to the basement.
I've owned a full complement of high end amps.Starting with several NAD's up through
Classe,McCormack,Audio Research, YBA,Krell and some very fine pre-amps also.
I can verify with confidence that the 50 watt LM3886 passive integrated amp I've built is just as satisfying to me as any of the above.
No doubt the pride of DIY has something do do with it but believe me it it didn't perform very well I'd drop it in a heartbeat!
Classe,McCormack,Audio Research, YBA,Krell and some very fine pre-amps also.
I can verify with confidence that the 50 watt LM3886 passive integrated amp I've built is just as satisfying to me as any of the above.
No doubt the pride of DIY has something do do with it but believe me it it didn't perform very well I'd drop it in a heartbeat!
thanks for the inspiration Guys to build this amp.....it sounds like its going to be a worth while project
Mothman you mentioned you built an Amp using the LM 3886.....are there any tips you can give me....I`m basically going to copy the circuit on the data sheet but if you modified I`d like to hear what you did>???
Cheers!!The DIRT®
Mothman you mentioned you built an Amp using the LM 3886.....are there any tips you can give me....I`m basically going to copy the circuit on the data sheet but if you modified I`d like to hear what you did>???
Cheers!!The DIRT®
JOE DIRT® said:thanks for the inspiration Guys to build this amp.....it sounds like its going to be a worth while project
Mothman you mentioned you built an Amp using the LM 3886.....are there any tips you can give me....I`m basically going to copy the circuit on the data sheet but if you modified I`d like to hear what you did>???
Cheers!!The DIRT®
Joe, don't do it like the circuit on the datasheet.
Go for the inverted configuration.
Do it as the Thorsten GC.
Banned
Joined 2002
Hey Joe,
There's an excellent full LM3886 schematic on Amp Chip Diy that a guy posted under the topic 'Please Clarify Ground Connections'it's still on the first page.
My amp is basically the same though I didn't use any of the snubbers or supply bypass caps.
Mine is a one box with 300va 18-0-18 with separate +/- supply rails that I paralell to each chip.
I'm using 3x 2200 BG fk's per side as I experimented with the usual 2x1000 and like the stiffer supply with the 4 ohm speakers I use.
I also use a 470uf bypass per supply at each chip for high frequency stability.I believe the data sheets speak to this.
Bacically the amp runs very cool with no signs of instability and vertually zero DC offset.
There's an excellent full LM3886 schematic on Amp Chip Diy that a guy posted under the topic 'Please Clarify Ground Connections'it's still on the first page.
My amp is basically the same though I didn't use any of the snubbers or supply bypass caps.
Mine is a one box with 300va 18-0-18 with separate +/- supply rails that I paralell to each chip.
I'm using 3x 2200 BG fk's per side as I experimented with the usual 2x1000 and like the stiffer supply with the 4 ohm speakers I use.
I also use a 470uf bypass per supply at each chip for high frequency stability.I believe the data sheets speak to this.
Bacically the amp runs very cool with no signs of instability and vertually zero DC offset.
Hey guys,
The more I read about gainclones (and there's A LOT to be read) the more I get excited about building some. I've been so busy lately I haven't had much time but now that I have new subs in my car I need to upgrade the amp(s) to something of decent quality. Much like everyone else, the SMPS is slowing me down though. Thanks for the gainclone tips.
Pete
The more I read about gainclones (and there's A LOT to be read) the more I get excited about building some. I've been so busy lately I haven't had much time but now that I have new subs in my car I need to upgrade the amp(s) to something of decent quality. Much like everyone else, the SMPS is slowing me down though. Thanks for the gainclone tips.
Pete
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