my first try at a LM3886 layout, any comments/suggestions? - Page 16 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 22nd February 2005, 06:11 AM   #151
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
I guess now it's time for my comparisons.

I was quite impressed initially by the snubber big caps supply and was using it for some time. It seemed to definitely add to the bottom end, making the sound more dynamic and full, more dimentional with better presence ( the vocals definitely stand out more) and the highs somewhat "cleaner".

Well, that was untill someone actually pointed out to me, that the sound was not natural. At that time I was using 100u BGN at the chip and Jensen 10,000/63 at the bridges. I was already posting about that here: http://www.diyaudio.com/forums/showt...431#post574431

I did more tests and comparisons, and indeed, when using snubber (not necessarily with 10,000u caps but even with 1000u) the effect is very similar: you loose the "noise" between the notes, something that can be related to as acoustic space or resolution. The effect of the snubber is almost like filtering, sound becomes drier (but with great dynamics) with somewhat pleasing presentation, but again, not very natural and not as liquid. Someone compared it to a synthesized sound.

I'm not saying that snubber or big caps are bad, some people will definitely like it, and I liked it too. But presently the snubber is out of my PS and I'm using 100u BG N caps alone (with AC power supply). If it wasn't for a snubber, I would have never tried that, but I also got very pleasantly surprised. I've been using it for more than a week now, and presently it's the best PS arrangement I had in a GC. The bass may be a bit weak, but OTOH it's very articulate and natural, with much better detail than the fat bass one gets with bigger caps, mids and highs though are extremaly good. While all of the filter caps have certain defficiencies, those single 100u BG N on amps board seem to be almost perfect. I can't really find any faults (except for weaker bass, but that can be fixed with biamping at 100Hz crossover frequency). The 100u BGN directly after bridges is way better than 1000u BG N (much more clarity and resolution in mids and highs), and it is better than using same caps with the batteries. I prefer AC PS to the batteries now. I tried adding different 1000u caps at the bridges, but the effect was always similar: dulling of highs, loosing speed and loosing the feeling of being there. The effect of batteries can be compared to the caps: since they store energy, I'm coming to conclusion that the less stored energy the amp is dealing with, the fresher the sound becomes.

1000BG STD are preferred by people who want deeper bass and more crisp sound. By comparison, 1000 BG N are somewhat mellow, the highs are nice but they don't stand out that well, and some people actually prefer STD version in direct comparison. 100u BG N when used alone, have none of deficiencies of bigger N caps: the highs are very crisp, clean and detailed, but at the same time have none of the traces of harshness, brightness or being analytical.

With regards to snubber and big caps, it's always a trade off: you either go for dynamics and strong bass, or you choose naturality, silky smooth and detailed highs available with small caps only.

If you are smart, you can choose bi-amping and have both
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 22nd February 2005, 06:33 AM   #152
diyAudio Member
 
Join Date: Aug 2003
Location: Prague,Czech Republic
Peter, this thing, which you call " naturality " by small caps, is distortion. But this distortion is so small, that your brain don't take it like distortion, but like noise between notes. It is not correct, " between the notes " must be silence.
  Reply With Quote
Old 22nd February 2005, 06:42 AM   #153
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
The silence is between the tracks. Between the notes, there is always something going on, like for instance the reverberations and decays of the original sounds, created by the recording space. I'm very well aware that this may be distortion, but to my ears it makes for much more real presentation.

On anechoic recordings there is indeed silence between the notes, but those recordings sound very artificial.

What I'm also noticing when using very small caps (100u in this case), is certain harmony and righteousness of the sound, that simply doesn't leave any question marks in your head if it is correct. You just know, that it can't be any other way (at least for a time being)
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 22nd February 2005, 06:53 AM   #154
diyAudio Member
 
Join Date: Aug 2003
Location: Prague,Czech Republic
Peter, comparision of amps is for nothing. Only right way is comparision with live music. Make it and you will know, whatabout I'm talking. In other case is it like talking about impresionism and it is neverending discussion, 'cos every man is different.
  Reply With Quote
Old 22nd February 2005, 01:32 PM   #155
Banned
 
Join Date: Mar 2003
Location: Lisbon, Portugal
Quote:
Originally posted by Peter Daniel
What I'm also noticing when using very small caps (100u in this case), is certain harmony and righteousness of the sound, that simply doesn't leave any question marks in your head if it is correct. You just know, that it can't be any other way (at least for a time being)
Quote:
Originally posted by Peter Daniel
What I'm also noticing when using very small caps (100u in this case), is certain harmony and righteousness of the sound, that simply doesn't leave any question marks in your head if it is correct. You just know, that it can't be any other way (at least for a time being)
Peter, your results are in the context of your system, mainly your speakers.
I once tried just 220uf caps and the amp didn't drive my Epos 11 speakers, the bass was not tight at all, it was more like a continuous tone that made everything vibrate, no definition (you may not notice this with your speakers).
As a result, the bad bass killed the midband and treble detail (as it always does).
I understand what you are saying about the detail, as with less demanding acoustic music the detail was very good.
But I felt like something was not really right, like pushed a treble tone control.
I have very good results in the mid/treble and good (with all the harmonics and vibration of the instruments, as I also like), tight, dynamic bass.
Btw, you can try two 4,700uf (or even three) caps in parallel (which I recommend) instead of single 10,000uf.
  Reply With Quote
Old 22nd February 2005, 02:01 PM   #156
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Yes, those results definitely apply to easy to drive speakers. I tried it at home using Raven/Triangle combo (Triangle used without crossover, full range), and in other system, with Omega speakers using Fostex drivers. I'm pretty much sure that it will not work with all setups, I'm quite surprised it works at all.

I'm not dismissing snuber and big caps, it definitely have certain appeal (well, I was impressed myself, if you remember). I'm only suggesting that it should not be considered as an obvious upgrade: it will greatly depend on personal taste, the system and listening priorities. It's just another way of enhancing your listening experience, but again, it may not be suitable for everyone. But I definitely encourage everybody to try it and decide for themselves.

However, I would also encourage anybody who have access to 100 BG N caps to try them alone in AC PS and report the findings. I don't think, myself, I will be going back to other configurations. But for more realistic bass (only on certain material), aditional low pass amp (for bi-amp setup) could be further enhancement.

PS: As you may notice in a picture, I also removed a series resistor a the input. As good as Caddock (or Vishay) was, I'm getting better resolution without it.
Attached Images
File Type: jpg t1.jpg (94.2 KB, 3189 views)
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 22nd February 2005, 08:22 PM   #157
lomtik is offline lomtik  Canada
diyAudio Member
 
Join Date: Nov 2004
Location: Toronto
I am liking your design!
It looks to me as this would be the cheapest amp with power supply kit having great reviews I've found recently!

Which version should I get, LM3886 or LM3875?

It looks like LM3875 is from another source and comes without PS, so I have to pay shipping twice. Is that so?

Is LM3886 Dual Mono kit more powerful than Stereo Kit due to double PS?

And finally, how many watts does this design deliver?


Thanks!
  Reply With Quote
Old 24th February 2005, 01:03 AM   #158
lomtik is offline lomtik  Canada
diyAudio Member
 
Join Date: Nov 2004
Location: Toronto
Quote:
Originally posted by lomtik
I am liking your design!
It looks to me as this would be the cheapest amp with power supply kit having great reviews I've found recently!

Which version should I get, LM3886 or LM3875?

It looks like LM3875 is from another source and comes without PS, so I have to pay shipping twice. Is that so?

Is LM3886 Dual Mono kit more powerful than Stereo Kit due to double PS?

And finally, how many watts does this design deliver?


Thanks!
I've sent an email as well, thanks for the reply.
  Reply With Quote
Old 24th February 2005, 03:51 AM   #159
diyAudio Member
 
edjosh23's Avatar
 
Join Date: Oct 2004
Location: Raleigh/Atlanta
I finally finished the amp! I hate high school, too much school work. Well this is the best sounding amp I've built so far, dc offset was -10mv and 11mv. There is no turn on or off thump, no hum. I got an emi filter from Brian that I think fixed that little problem. But I've now listened for about 4 minutes, and it sound quite good. I'll post later with another review.

Thanks,

Josh
  Reply With Quote
Old 24th February 2005, 07:38 AM   #160
BrianGT is offline BrianGT  United States
diyAudio Moderator Emeritus
 
BrianGT's Avatar
 
Join Date: Jan 2002
Location: near Atlanta, GA
Send a message via AIM to BrianGT
I finished prepared the first batch of LM3886 kits tonight, and will be taking them to the post office tomorrow morning.

As for the packages, on the first 1/2 of them, I taped the 1N4004 diodes (used for rectification for the LED power supply) to the outside of the padded mailer (which will be put inside the USPS priority mailer), so don't discard the diodes when you unpack the kit. I forgot about this component until 1/2 way through the kitting process tonight. Everything else should be in order. It has taken me a cumulative average of 15 minutes per kit for putting together the new kits, which is considerably more than the LM3875 kits, but should decrease now that I have the method worked out.

I will get the remaining (majority was done tonight) orders put together and out by the end of week.

I will be unexpectively be out of town from this Saturday until Monday (family issues, flying home), and also next week from Wednesday until Saturday (last minute business trip to California), but I will try to keep up with e-mail during that time, and resume filling the orders when I am back in Atlanta.

The US orders that shipped out should have received a USPS confirmation mail.

--
Brian
Attached Images
File Type: jpg kits.jpg (77.7 KB, 2926 views)
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 12:43 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki