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Old 23rd September 2008, 02:11 PM   #1
jaya000 is offline jaya000  India
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Default Damping factor in DIY amp

Many pro audio amplifier manufacturer talk about high Damping factor.
If it is really effective in subwoofer application, then how to improve damping factor in diy amplifers?
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Old 23rd September 2008, 02:33 PM   #2
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Lots of NFB and bring the feedback pick-off point right to the output terminal, assuming no output network. If there's a network between the feedback point and the output terminal, and there usually is, be sure the coil is heavy gage wire, along with the rest of the wiring. Be sure the return wiring is heavy as well. The benefit of very high damping is debatable, since any length of speaker wire quickly destroys it anyway. It's more of a marketing thing.
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Old 23rd September 2008, 03:21 PM   #3
okapi is offline okapi  United States
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makes me want to try building a chip amp powered speaker with the chips mounted right at the driver terminals. i guess most people would suggest an active crossover with this type of set-up but i think i would like to try a passive line level cross over. i would keep the signal digital right up to the speaker.
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Old 23rd September 2008, 06:21 PM   #4
darian is offline darian  France
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So, even keep the crossover in the digital realm and buy a DCX2596 or even two, one per loudspeaker. It's apparently one of the best system you can dream of according to a lot of people!
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Old 24th September 2008, 04:49 AM   #5
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Quote _djk_
Edit Post Quote Reply Posted: September 01 2007 at 9:04am

The braking effect in a speaker system is largely the suspension stiffness, and the design of the box. The huge amount of air mass in a horn makes the driver stop pretty good.

'Damping factor' has little or nothing to do with it, largely because the Re of the driver destroys the factor to just over 1 even if the output impedance is zero from massive negative feedback.

Transients in music resemble a square wave. The large caps in amplifiers take a finite amount of time to dump the required current in the leading edge of the square wave. Adding a small bypass cap (usually 22uF~100uF) across each main filter cap will make the bass sound much 'tighter'. It will make no measureable difference in the power out, frequency response, of DF or the amplifier; yet it will change the sound more than you can imagine. Over 90% of all amplifiers do not have bypass caps. The ones with rock-hard bass do.

Even if your amplifier has bypass caps, they wear out quickly because of the huge currents involved. They seldom last more than a few years before needingt replacement.
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Old 24th September 2008, 09:04 AM   #6
jaya000 is offline jaya000  India
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Thanks djk!
U r helpful as usual.
There r 16 electrolytic capacitors in the amplifier.
This means i hv to use 1nos. 6 22~100 ufd capacitors. For kick bass what value between 22~100 ufd preferable.
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Old 24th September 2008, 09:46 AM   #7
forr is offline forr  France
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Hi jaya000
---how to improve damping factor in diy amplifers?---

http://www.diyaudio.com/forums/showt...14#post1616914

Hi Darian,
--- DCX2596---
:-)
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Old 24th September 2008, 10:20 AM   #8
mhtplsh is offline mhtplsh  India
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Forr :
Quote:
Hi JLO, "it is not so easy to change a Q just by a switch or a remote control so who really did it ?" Q of a driver can be manipulated, using either a transform, for loads having a 2nd order hi-pass behaviour (it can easily be done by a numeric processor), or an amplifier with positive or negative output resistance, for any kind of loads.
This is what mentioned in the link of ur above post.
There is nothing about damping factor improvement as i see.
Kindly clarify.
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Old 24th September 2008, 10:56 AM   #9
djk is offline djk
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Most big amps have a ±low rail and a ±high rail. The caps on the low rail must be on the outside of the OR-ing diodes, right on the main filter caps (the outputs are connected on the inside of the OR-ing diodes).

A Crest CA12 uses four 30,000uF (actually eight 15,000uF) in the main supply. The high rails have 22uF electrolytic plus 1.5uF film, the low rails have 220uF electrolytic plus 2.2uF film.

Sometimes you may have to place a small resistor (snubber) in series with the film caps. They may cause oscillations if the grounding scheme is not right. I generally try around 1R, or omit the film caps if I have a problem.

Click the image to open in full size.

D3, D4 are the OR-ing diodes.
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Old 24th September 2008, 04:06 PM   #10
jaya000 is offline jaya000  India
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Thanks djk!
herewith attached the powersupply of a big amplifier i saw in another post. So i hv to add capacitors on the filter capacitors right in the powersupply.
This is just to understand properly.
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File Type: jpg power supply.jpg (37.3 KB, 384 views)
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