I have been reading this forum trying to learn about these amps.
There seems to be so many different ways to build them.
Has anybody sat down and listen to them all? Is there an agreement as to which design is best?
If someone can point me to where to get a good pcb and design it would be welcome, cost is not an issue, I want the best.
There seems to be so many different ways to build them.
Has anybody sat down and listen to them all? Is there an agreement as to which design is best?
If someone can point me to where to get a good pcb and design it would be welcome, cost is not an issue, I want the best.
Well, how much power are you looking at? Are you looking at low power (about 0-20W) Medium power (about 21-70W) or high power (71W+)?
Low power, the best is the LM383, an 8W chip. it sounds great, but has been discontinued, so if you can get it it might cost a bit more. Also, the LM1875, a 20W chip is good.
Medium power, The LM3886, a 68W into 4-ohm chip. It also has a mute.
High power, I don't know. The LM4651/52 looks good, but ive never used it or any other class d amp before.
Hope this helps, Mike
Low power, the best is the LM383, an 8W chip. it sounds great, but has been discontinued, so if you can get it it might cost a bit more. Also, the LM1875, a 20W chip is good.
Medium power, The LM3886, a 68W into 4-ohm chip. It also has a mute.
High power, I don't know. The LM4651/52 looks good, but ive never used it or any other class d amp before.
Hope this helps, Mike
For the beginner, one of the best places is the Decibel Dungeon website - there you can follow a step-by-step guide to hard-wiring (no pcb involved) your own inverted gainclone (amongst other things) using the LM3875 chip.
Whether or not it is 'the best' is a different issue - there is no such thing and you hear arguments for and against each type, with nobody really coming to any conclusion - most people seem to eventually build them all anyway
If somebody tells you type 'whatever' is the best, they are lying. If you are indeed a beginner, best to keep it simple so follow the basic inverted GC on DD.
Whether or not it is 'the best' is a different issue - there is no such thing and you hear arguments for and against each type, with nobody really coming to any conclusion - most people seem to eventually build them all anyway
If somebody tells you type 'whatever' is the best, they are lying. If you are indeed a beginner, best to keep it simple so follow the basic inverted GC on DD.Ropie said:For the beginner, one of the best places is the Decibel Dungeon website - there you can follow a step-by-step guide to hard-wiring (no pcb involved) your own inverted gainclone (amongst other things) using the LM3875 chip.
Whether or not it is 'the best' is a different issue - there is no such thing and you hear arguments for and against each type, with nobody really coming to any conclusion - most people seem to eventually build them all anyway
I agree with most of it. The only comment is the Inverting GC COULD be more prone to oscillation than the NIGC (LM3875) (depends on the actual layout and setup). For NIGC is easier to get higher input impedance without a preamp (10k vs 22k or more; whether you need it or not is your call). Higher Zin would give you better base if you use marginal value Cin (if you have one, I don't use any).
Sound: Different opinions on that. Well assembled amps would sound the same to me (I don't have very sensitive years, though the dif between the GC and The 70W Yamaha is so big in favour of the GC).
I'm extremely happy with what I build (NIGC, no preamp). Sounds incredible to me.
http://home.ca.inter.net/~cfraser/Gainclonehome.htm
http://www.platenspeler.com/diy/uk_index_body.html
The best design is given in National's application notes. You can further improve it by playing with components, or even reducing the parts count. I would strongly recommend using around 1000u on rails, if you want the best mids and highs clarity.
Recently, a new design emerged, which looks quite promising. If you consider it comes from one of the pioneers of GC movement, maybe you should try to built that one?
http://www.ampchipdiy.com/phpBB2/viewtopic.php?t=85&sid=148f09ae5b6659cfd0900b95399fb69c
Recently, a new design emerged, which looks quite promising. If you consider it comes from one of the pioneers of GC movement, maybe you should try to built that one?
http://www.ampchipdiy.com/phpBB2/viewtopic.php?t=85&sid=148f09ae5b6659cfd0900b95399fb69c
If you need to ask which is the best configuration, you are not ready to build that one!
There is no 'best' one! As has been said, choose one of the circuits and build it well, experiment with the components like Peter says and listen, listen and listen!
If you build a separate PSU section, it's not that expensive to build three or four amp circuits (as there are so few components) and then compare them for yourself.
I have described how I built both the inverted and non-inverted designs on Decibel Dungeon and I am too long in the tooth to say which is the 'best'!
Peter Daniel: You recommand using 1000 uf for the rail, but if I only use one transformer, I need two 1000 uf cap on each channel or only two for the two channel ??? With one transfo, if I use two cap by channel, I will have 2 cap in parallele.....so 2000 uf and I don't think that what we need !
Thank
Thank
I don't think it's such a big deal if two 1000u caps in parallel efectively give you 2000u. I think the type of caps is more important than the actual value, maybe 2000u instead of 1000u sound as good. But don't use 10,000u as it may sound less good
It is propbably better to place the caps as close to the chips as you can, but i never checked it out how important it is
It is propbably better to place the caps as close to the chips as you can, but i never checked it out how important it is
humm
I made a stereo set, first try = great, had to sell it because my first guest wanted to take it home.
second set I had problems , turned out to be a problem with the ground! (thanks for the awesome assistance Gregc.
I just finished my third set again using the LM3875's some different brand of components in caps and resistors, but my ears don't want to go along I think, it seems no different in sound to me. One problem is that i cannot connect them to my 70's Epicure speakers = too sensitive, I can only regulate the volume within 1/4 of the track, and then the sound becomes tooooo loud. When using other speakers like Pioneer of Audax there is no problem
I have components for 3 more and then I am going to start new speakers with the Jordan X92S
Right now I am using transformers from Apex, one (200 VA) for both chips and hear no irregularities.
I must say that I was quite impressed the first time using them, There were noises from the recording coming out of the speakers that I had never heard before, expecially when listeing to live classical recordings.
Jean-Pierre
After that I am starting with the Lm3886 .....
I made a stereo set, first try = great, had to sell it because my first guest wanted to take it home.
second set I had problems , turned out to be a problem with the ground! (thanks for the awesome assistance Gregc.
I just finished my third set again using the LM3875's some different brand of components in caps and resistors, but my ears don't want to go along I think, it seems no different in sound to me. One problem is that i cannot connect them to my 70's Epicure speakers = too sensitive, I can only regulate the volume within 1/4 of the track, and then the sound becomes tooooo loud. When using other speakers like Pioneer of Audax there is no problem
I have components for 3 more and then I am going to start new speakers with the Jordan X92S
Right now I am using transformers from Apex, one (200 VA) for both chips and hear no irregularities.
I must say that I was quite impressed the first time using them, There were noises from the recording coming out of the speakers that I had never heard before, expecially when listeing to live classical recordings.
Jean-Pierre
After that I am starting with the Lm3886 .....
The LM1875 sounds quite nice, and is capable of enough power to drive moderately efficient speakers to a loud level.
From what I've heard from the various "Overture" National ICs, the 1875 is more musical than the 3875 or 3886. Though all three are fine choices, the latter two are bit more neutral.
From what I've heard from the various "Overture" National ICs, the 1875 is more musical than the 3875 or 3886. Though all three are fine choices, the latter two are bit more neutral.
I presume that this is with the inverted amp! Try building a stepped attenuator as shown on my Gainclone FAQ page.
Cost is about 10UKP, depending on which resistors you use. For a good sounding job, use matched carbon films for the series resistor and 1% metal films for the shunts.
Apart from sorting out the control problem, it sounds a lot better than a pot!
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