jnb [/i][B]I have found the LM3875/86 ilk to be somewhat fatiguing and have sought to find an improved sound.[/B][/QUOTE] I must be lucky never to have heard a bad example. Early builders used the rules of thumb that: (1) rather use point-to-point wiring to minimise the length of the conduction path of the feedback network (2) use undersized power supply capacitors; this yields the best sound due to these chips being very layout-sensitive. Subsequent designers (See PA3) managed to get good performance out of these chips without necessarily going the conventional wisdom route. [QUOTE][i]Originally posted by tinitus said:
No amp should be used up to its limit, especially since we don't control the transients in music. Doing so would inevitably result in clipping distortion. Some amps handle clipping better than others (are more forgiving) while some of the National chips simply "lose it". This could explain jnb's experiences.
The little wiggle on the LM3886 graph above looks strange. Otherwise I suspect that the seemingly increased distortion at low levels is mostly a PS noise thing. IOW what is seen is the power supply noise becoming a bigger part of the signal. People often forget that these graphs shows THD+N where N stands for noise. 
About LM3875/86 having a fatiguing sound. Try shape i with a shallow lowpass filter. I have a friend that prefer his LM3886 this way. It's actually a RF lowpass filter on the input that is rolloing of slightly in the audible range. Not much, only 1dB or less at 20kHz but it makes the amp sound "better". It may be partly due to less power in the top octave but could also be due to less HF crap coming into the amp causing IM.
For what it's worth, I have listened to his LM3886 amp (without the LPF) in a blind test using a pro soundcard and Sennheiser HD600. The music signal sounded indentical via the amp as in loopback mode... Chances are that it's "all the other" amps that are pleasantly colored. Personally I prefer neutrality and a slight EQ where needed.
To be fair I should alse mention that I made a point to point LM3886 amp for a friend a couple of years ago and comparing that amp to my class A amp there was a slight loss of low level info. A sligh grain in the higher octaves as well. Don't know if it was a matter of poor execution.. maybe oscillation that casued this or if it was a signature of the amp and it's crossover distortion. Swithcing noise from poorly executed PS could be another explanation.
/Peter
About LM3875/86 having a fatiguing sound. Try shape i with a shallow lowpass filter. I have a friend that prefer his LM3886 this way. It's actually a RF lowpass filter on the input that is rolloing of slightly in the audible range. Not much, only 1dB or less at 20kHz but it makes the amp sound "better". It may be partly due to less power in the top octave but could also be due to less HF crap coming into the amp causing IM.
For what it's worth, I have listened to his LM3886 amp (without the LPF) in a blind test using a pro soundcard and Sennheiser HD600. The music signal sounded indentical via the amp as in loopback mode... Chances are that it's "all the other" amps that are pleasantly colored. Personally I prefer neutrality and a slight EQ where needed.
To be fair I should alse mention that I made a point to point LM3886 amp for a friend a couple of years ago and comparing that amp to my class A amp there was a slight loss of low level info. A sligh grain in the higher octaves as well. Don't know if it was a matter of poor execution.. maybe oscillation that casued this or if it was a signature of the amp and it's crossover distortion. Swithcing noise from poorly executed PS could be another explanation.
/Peter
I didnt say that I use my amps to the limit ... but they can do just that without any unpleasent or severe clipping
Meaning excactly that with normal use it will have plenty of headroom with clean undistorted power available fore transients ... I thought that was obvious
Its only with a single pair of output transistors(MJL21193/94) so very soon I will build a pair of monoamps with 4 pairs of the same transistors ... supply will be double mono with 50Vdc and 2kw each
Meaning excactly that with normal use it will have plenty of headroom with clean undistorted power available fore transients ... I thought that was obvious
Its only with a single pair of output transistors(MJL21193/94) so very soon I will build a pair of monoamps with 4 pairs of the same transistors ... supply will be double mono with 50Vdc and 2kw each
Hi G,gaetan8888 said:
do you still have that 60W Crimson? Which model? BJT or FET? fully protected or series vii?
Can you offer an opinion on it compared to chipamps?
I have chipamps inside my Tannoys.
My Crimson 1704vii can wipe the floor against them, for all types of music, at all listening levels. And they were very cheap at the time.
AndrewT said:
Hello Andrew
It was a BJT model using 2n3055 output with a low pass 22khz input filter, a nice kit with a toroidal power transformer. That was with an electronics protection.
I lend to a friend long time ago, it was a very very good sounding amp, much better than chip-amp, better soundstage and dynamic.
Bye
Gaetan
Member
Joined 2009
Paid Member
P3A provided with a good bookshelf speaker, even for a simple design. The sonic qualities is superior.One of the best sounding diy ss amp for me.
Try this, beats out the P3A
http://www.diyaudio.com/forums/solid-state/245619-tgm8-amplifier-based-rod-elliot-p3a.html
Best Amps
The best amp for your first amp is one where the following apply:
- a lot of people have built it and can help with problems
- has PCB and parts available
- has a building guide of sorts
- sounds good
- doesn't need a huge heat sink
- doesn't use expensive or rare parts.
- are cheap to build
The amps that fit this profile are chipamps/"gainclones", the "honey badger" and the DX amplifiers. P3A also. I may have missed some (probably did) but you get the point.
I have made a lot of amps over here and I always recommend the DX (pick the newest version) to people who don't want to make big monster amps. To my ears its absolutely amazing (I made the HR-II), I am astonished at how good it is every time I turn it on.
Of course you should also make a chipamp since they are so cheap and easy, nothing to lose for a diy project.
The best amp for your first amp is one where the following apply:
- a lot of people have built it and can help with problems
- has PCB and parts available
- has a building guide of sorts
- sounds good
- doesn't need a huge heat sink
- doesn't use expensive or rare parts.
- are cheap to build
The amps that fit this profile are chipamps/"gainclones", the "honey badger" and the DX amplifiers. P3A also. I may have missed some (probably did) but you get the point.
I have made a lot of amps over here and I always recommend the DX (pick the newest version) to people who don't want to make big monster amps. To my ears its absolutely amazing (I made the HR-II), I am astonished at how good it is every time I turn it on.
Of course you should also make a chipamp since they are so cheap and easy, nothing to lose for a diy project.
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