Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

My amp is clipping with new speakers
My amp is clipping with new speakers
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
Thread Tools Search this Thread
Old 1st January 2012, 12:56 AM   #1
benproiii is offline benproiii  United States
diyAudio Member
Join Date: Aug 2010
Location: New York
Default My amp is clipping with new speakers

I just built the Zaph|Audio SR71 Kit from Madisound and I hooked them to my DX HRII amplifier running off +/- 35V and it is much quieter then my old speakers (Polk Audio M10's) and when I turn the volume up pretty loud the speakers are all distorted. I know its the amp because my AKM4396 DAC and Pass B1 Preamp are not clipping the signal (checked full vol. sign wave with scope). Would it be OK the increase the supply voltage to 49.7V without any modifications. the transformer I'm using has a 25V tap (using now) and a 35V tap. Thanks.
  Reply With Quote
Old 1st January 2012, 02:20 AM   #2
Stefanoo is offline Stefanoo  Italy
diyAudio Member
Stefanoo's Avatar
Join Date: Apr 2006
Location: italia - ora USA -WI
nope, don't do that unless you have an overkill heatsink.
Also, if there is distortion, there might be something not properly soldered or something defective.
you need to make some measurements and check dustortion vs input level.
  Reply With Quote
Old 1st January 2012, 05:34 AM   #3
gootee is offline gootee  United States
diyAudio Member
Join Date: Nov 2006
Location: Indiana
Maybe the speakers are just much less efficient than whatever you were using previously. When running 150 W/ch into my 4-Ohm Magnepan MG-12 speakers (supposedly rated 86dB/2.83v/m @500Hz), my amp would start to clip before I could get the speakers as loud as I sometimes wanted them to be. I bought an amp that can push 400 W/ch @ 4 Ohms (Adcom GFA-585) and I've never seen it even get close to clipping, and can now get the speakers to play so loudly that they begin to self-distort. But that would just be as a test because they would be "too loud" for me at that point, even if they weren't distorting. So now I am happy with the system's SPL capability.

In other words, you might simply need either more-efficient speakers or more available power.

Last edited by gootee; 1st January 2012 at 05:41 AM.
  Reply With Quote
Old 1st January 2012, 06:10 AM   #4
jaycee is offline jaycee  United Kingdom
diyAudio Member
Join Date: Apr 2004
Location: Norwich, UK
Check your DAC is happy to drive a 12K impedance. As you have a 'scope, this is pretty easy, just check the signal at the base of Q1.
  Reply With Quote
Old 1st January 2012, 06:54 AM   #5
godfrey is offline godfrey  South Africa
diyAudio Member
Join Date: Nov 2009
Location: Cape Town
Changing from the 25V to the 35V taps will allow about double the power, but some other changes will be needed:

a) The zener diodes that regulate the supply voltage for the front end of the amplifier will have to be changed from 16V to (IMO) 22V.
b) Check that all the capacitors are rated to withstand the higher voltages.
c) As Stefano mentioned, you may need bigger heatsinks depending what you have and how hot they get.
d) I'd strongly recommend adding a second pair of output transistors (and associated resistors).
  Reply With Quote
Old 1st January 2012, 10:57 AM   #6
AndrewT is offline AndrewT  Scotland
diyAudio Member
Join Date: Jul 2004
Location: Scottish Borders
Changing the PSU voltage requires a complete re-assessment of the amplifier working conditions. It is in effect a re-design.
regards Andrew T.
  Reply With Quote
Old 1st January 2012, 12:42 PM   #7
tvrgeek is offline tvrgeek  United States
diyAudio Member
Join Date: Dec 2009
Location: Md
That is a superb speaker design, so I suspect something else terribly wrong. They are not that inefficient. I hate to go there, but have you triple checked everything like having a woofer out of phase, or peculiar impedance? Are you expecting a monitor size speaker to fill a stadium, boost the bass or anything not for what it was designed?

There are some speakers that just seem to want big power to "open up", as a totally non scientific term. But I have used enough 10W amps and 200W amps winding up with most of my amps are about 60W in my serious room, and 30 in my office.
  Reply With Quote
Old 1st January 2012, 03:35 PM   #8
benproiii is offline benproiii  United States
diyAudio Member
Join Date: Aug 2010
Location: New York
They only distort on the highest volume of my pass B1 preamp which has no gain, I will only have it on the highest volume on quietly recorded songs. the distortion is not that bad just some edgy vocals. I was not going to listen to them that loud but I am worried about the ability to handle very dynamic passages.

I plugged them into my Onkyo receiver and they don't distort even on extremely high SPL. The amp in it only has 1 output pair per channel and runs off 65V+/- would that exceed the SOA of the output transistors? Why can't I run the HRII amp off 50V+/- this amp runs the amp off 65!
Attached Images
File Type: jpg AMP.jpg (195.2 KB, 326 views)
  Reply With Quote
Old 1st January 2012, 07:30 PM   #9
5th element is offline 5th element  United Kingdom
diyAudio Member
5th element's Avatar
Join Date: Oct 2002
Location: England
If you take 0dB digital to equal the maximum volume possible (usually about 2Vrms on the DAC output), then you could play with sine-wave sweeps @ this level and scope the amplifier output to see at what volume you can safely set the pre-amplifier to such that the amplifier does not clip. If the amplifier is clipping because you're running into limits of the rail voltages then you need not have the loudspeakers connected to do this. However if the amplifier is clipping due to the protection kicking in, then you will need to carry this out with the loudspeakers connected. If done at high levels (which this is) do it with caution as you might exeed the woofers physical capabilities if the sine sweep sends 10hz etc through them.

As 0dB is the absolute maximum that can be produced by the DAC, if you therefore set the max volume such that the amplifier does not clip when driven at this level, then you will know that regardless of how dynamic the music you will never cause the system to clip.
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Now with website! www.5een.co.uk under construction.
  Reply With Quote
Old 1st January 2012, 07:57 PM   #10
benproiii is offline benproiii  United States
diyAudio Member
Join Date: Aug 2010
Location: New York
It did the test with my scope and the output of the preamp at 0db is a perfect sine wave and the output of the amp with a 8ohm load will start to clip at about 15V p-p which is the volume control at 9 o'clock. I thought that the amp would swing more volts than that before clipping at +/-35V supply
  Reply With Quote


My amp is clipping with new speakersHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Early clipping with JX Amp JBL4435 Pass Labs 32 8th December 2011 07:05 AM
Recovery from clipping, soft clipping hahfran Solid State 49 23rd February 2010 01:03 AM
Super T Amp Clipping ! any suggestions ? audioaction Class D 4 5th January 2010 03:11 AM
Amp clipping detector Bazukaz Solid State 8 27th February 2009 02:47 PM
Clipping and amp power supply digitaldisaster Chip Amps 3 3rd September 2007 03:53 AM

New To Site? Need Help?

All times are GMT. The time now is 10:02 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio