Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

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 14th June 2011, 11:29 AM   #1771
diyAudio Member
 
Join Date: Mar 2011
Quote:
Originally Posted by ThokN View Post
We have completed our Boominator now, but I have a question regarding distortion and using Amp9-B..

First of all it plays very, very loud with the Amp9, but when we turn it up to full, it distorts. If we say the volume goes from 0-10, then the distortion comes in between 9 and 10, so not a big issue. But we tried to play around with the EQ of the mp3-player and when we cut off the lowest band, I think it is under 125Hz, then the distortion disappears.

It is not the Amp9, but the speakers that distorts, so my question is why this is happening, and if we could put an input-cap on our input-cable right before the amp to cut off the low frequencies that makes it distort at maximum volume?

Did we build the box incorrectly, or is it just designed to play with Amp6 at max without distortion, and not Amp9 without distortion?

Also, our ports/handles have rounded edges, but they are not rounded...uhm...at the edges around the handle, if you know what I mean? What I mean is that we have not used an 'overfræser'/'power router' to smooth the handles, and I'm wondering if that has a negative impact on the sound?
I've built a replica of the original boominator and it distorts if I connect my laptop and turn it all the way up. My Amp6Basic is set with the highest gain possible so that might be the reason why mine distorts a little bit. I could imagine without being sure that you just reached the limit of the speakers.

Can anyone confirm both cases? I have read that the reason it distorts is simply just because i have reached the limits of the amp6basic. And it is not like it does'nt play loud! IT DOES
  Reply With Quote
Old 14th June 2011, 11:50 AM   #1772
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
ThokN, yes without changing the input caps on the amp9b you will run into the limit of what the speakers can handle at around full volume. This is what it is designed for.

DanielClark91, you have indeed reached the limit of what the amp6b can handle.

So just to be absolutely clear on this. It's two different circumstances. One where the limit of the amp is reached, and one where the limit of the speakers is reached. Now there's nothing you can do to extract more power out of the amp6b, so live with it. On the amp9b though you can squeeze the last bit of performance out by changing the input caps on the amp.
  Reply With Quote
Old 14th June 2011, 11:52 AM   #1773
euforia is offline euforia  Sweden
diyAudio Member
 
Join Date: Nov 2005
Or maybe the signal gets distorted by the AMP9/6 after all. Hook the boominator up to a larger amp, like a PA-amp or your homecinemareciever and come back with results. I find it hard to believe that the 10" woofer is the weak link when we have an HPfilter on it. (the 0,47uF input cap)
To me it is because we only have a 12V system that is fused to 4A. The woofers crave more power to produce higher SPL. Let me know if im wrong!

Edit: Saturnus, didn´t see your reply before i posted mine=)

Last edited by euforia; 14th June 2011 at 12:10 PM.
  Reply With Quote
Old 14th June 2011, 11:59 AM   #1774
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Quote:
Originally Posted by euforia View Post
Or maybe the signal gets distorted by the AMP9/6 after all. Hook the boominator up to a larger amp, like a PA-amp or your homecinemareciever and come back with results. I find it hard to believe that the 10" woofer is the weak link when we have an HPfilter on it. (the 0,47uF input cap)
To me it is because we only have a 12V system that is fused to 4A. The woofers crave more power to produce higher SPL. Let me know if im wrong!
Again. We're talking about 2 different things here. With the amp6b (or an amp9b on 12V) the limit is the amp, or really the supply voltage. It's simply power limited.

With the amp9b on 24V the situation is a bit different, then it's the woofers that give up, and that has something to do with the design because the necessary overtuning of the ports lowers the cabinets ability to dampen cone movements under the tuning frequency. So in order to get control back you have to limit those frequencies electronically. In it's simplest form that's just changing the input caps.
  Reply With Quote
Old 14th June 2011, 12:14 PM   #1775
ThokN is offline ThokN  Denmark
diyAudio Member
 
Join Date: Jan 2010
Location: Copenhagen
Quote:
Originally Posted by Saturnus View Post
Again. We're talking about 2 different things here. With the amp6b (or an amp9b on 12V) the limit is the amp, or really the supply voltage. It's simply power limited.

With the amp9b on 24V the situation is a bit different, then it's the woofers that give up, and that has something to do with the design because the necessary overtuning of the ports lowers the cabinets ability to dampen cone movements under the tuning frequency. So in order to get control back you have to limit those frequencies electronically. In it's simplest form that's just changing the input caps.
Great, makes sense! Do the input caps have to be changed on the Amp9 board, or can we add the cap to the mini-jack cable right before it goes into the amp?

And what kind of cap should it be? MKT?
  Reply With Quote
Old 14th June 2011, 12:56 PM   #1776
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Quote:
Originally Posted by ThokN View Post
Great, makes sense! Do the input caps have to be changed on the Amp9 board, or can we add the cap to the mini-jack cable right before it goes into the amp?

And what kind of cap should it be? MKT?
MKT will do but series and parallel connecting caps don't work the way you appearantly think it does.

Here the 2 rules:

The equivalent capacitance of two capacitors connected in parallel is the sum of the individual capacitances.

So for parallel: Ct=C1+C2

The reciprocal of the equivalent capacitance of two capacitors connected in series is the sum of the reciprocals of the individual capacitances.

And for series: Ct=1/(C1+C2)

So yes, technically you could add it on the input cable but caps in series do not sound very good and should be avoided at all cost.

Last edited by Saturnus; 14th June 2011 at 01:00 PM.
  Reply With Quote
Old 14th June 2011, 01:05 PM   #1777
ThokN is offline ThokN  Denmark
diyAudio Member
 
Join Date: Jan 2010
Location: Copenhagen
Quote:
Originally Posted by Saturnus View Post
MKT will do but series and parallel connecting caps don't work the way you appearantly think it does.

Here the 2 rules:

The equivalent capacitance of two capacitors connected in parallel is the sum of the individual capacitances.

So for parallel: Ct=C1+C2

The reciprocal of the equivalent capacitance of two capacitors connected in series is the sum of the reciprocals of the individual capacitances.

And for series: Ct=1/(C1+C2)

So yes, technically you could add it on the input cable but caps in series do not sound very good and should be avoided at all cost.
Okay well...that means it will be a permanent mod to the Amp9, but then I'm affraid that it will lack bass when the volume is not turned all the way up. I see that a 0.47uF cap has been mentioned, so if I change it to that, under what frequencies will it cut off? I've tried to read about this on the web, but I haven't found any text that explains input-caps and their crossover-values.

If you were me, what would you do?
  Reply With Quote
Old 14th June 2011, 01:23 PM   #1778
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Quote:
Originally Posted by ThokN View Post
Okay well...that means it will be a permanent mod to the Amp9, but then I'm affraid that it will lack bass when the volume is not turned all the way up. I see that a 0.47uF cap has been mentioned, so if I change it to that, under what frequencies will it cut off? I've tried to read about this on the web, but I haven't found any text that explains input-caps and their crossover-values.

If you were me, what would you do?
The 0.47uF is the optimum for with the 22Kohm input impedance of the amp6b (unless modified). The amp9b has 50Kohm input impedance.

I'd recommend something like 0.1uF for the amp9b. It shouldn't affect bass performance in any way, just limited cone movements you can't hear anyways. In fact, if anything it should result in even better midrange.
  Reply With Quote
Old 14th June 2011, 01:28 PM   #1779
ThokN is offline ThokN  Denmark
diyAudio Member
 
Join Date: Jan 2010
Location: Copenhagen
Sounds good! Btw. we have the input-trafo installed also, so does it work with that?
  Reply With Quote
Old 14th June 2011, 01:35 PM   #1780
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Quote:
Originally Posted by ThokN View Post
Sounds good! Btw. we have the input-trafo installed also, so does it work with that?
Doesn't make any difference
  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 04:35 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2