Quality of Digital Designs amps?
02-14-2009, 03:04 PM
#12
Goalie Man
Join Date: May 2003
Posts: 1,412
true damping factor over 200 is fantastic but the higher the number the better... as far as i know damping is the amps ability to control the woofers motion, so the higher the damping, the more control over the sub.now dd has a rep for monster power but a little on the unreliable side, but mike has assured me that that problem has been fixed and these amps are as reliable as the mtx!! (shamless plug lol!!). go dd.. more power, better looking, better reliablilty. now the best thing to do call keith and go down to his shop and check one of those amps out, he will measure it there for you so you can get real world #. then zip over to audio lines and they will do the same with an audison, and then make your decision.
02-14-2009, 04:29 PM
#13
People usually associate importance to damping when they speak of subs, not to much for MB and MR and tweets.
Basically damping changes with frequency, the lower the freqency the less damping there is which is why subs would see the benefit if DP was a spec worth anything.
When you look at damping rarely will it say at what frequency, damping is not a static number.
Basically how fast a speaker will come to rest or move with control is far more dependant on the speakers design and has really nothing to do with damping of the amp. Also there are a few web pages out there that explain with calculations why it is useless as oposed to mindless banter (like this post coincidently) that simply states the more the better. I suppose it would be possible to have a damping so low that it could be noticable, but that would prob be around 20 or less.
Also worth noting, at the other end of the spectrum some peolpe are affraid of to much DP fearing it might cause the "dreaded" negetive feedback.
The info is out there for anyone who really cares to know how unimportant DP is. Most people prefer not to however.
Basically damping changes with frequency, the lower the freqency the less damping there is which is why subs would see the benefit if DP was a spec worth anything.
When you look at damping rarely will it say at what frequency, damping is not a static number.
Basically how fast a speaker will come to rest or move with control is far more dependant on the speakers design and has really nothing to do with damping of the amp. Also there are a few web pages out there that explain with calculations why it is useless as oposed to mindless banter (like this post coincidently) that simply states the more the better. I suppose it would be possible to have a damping so low that it could be noticable, but that would prob be around 20 or less.
Also worth noting, at the other end of the spectrum some peolpe are affraid of to much DP fearing it might cause the "dreaded" negetive feedback.
The info is out there for anyone who really cares to know how unimportant DP is. Most people prefer not to however.
02-15-2009, 08:36 PM
#15
500 Watt CAFz'r
Join Date: Jan 2008
Posts: 537
The spec is derived by: speaker impedance / amp output impedance. The simple story is that the amp "shorts" the ouput of the voicecoil when it tries to move contrary to the amp's ouput signal. Since the coil is in a magnetic field it will generate a voltage proportional to it's velocity. If it is not moving in agreement with the music program the amp will short this voltage and sap the excess energy. That's the semi-accurate over-simplified description.
If you consider the high advertised DF numbers, the amp's output impedance must be very small. This is achieved by negative feedback. For some reason negative feedback has become a bad word in audio circles but in my opinion it's a very good thing. When a speaker continues to oscillate after a note has passed the voltage generated by the moving voicecoil is fed back into the input of the amp, only reversed in polarity. Hence the name negative feedback. The amp then induces a current opposite to the one generated by the voice coil causing cancellation in an effort to reduce the cone's motion to zero. In reality the amp does not have an iron grip on the coil's motion. The electrical control is "loose" and the kinetic energy of the moving mass dominates the system.
This is the reason why damping factors over ~200 are nice, but not something to pay extra for. Two hundred is not a magic number but above this point we are getting well into the region of deminishing returns. No matter how good the amp is at cancelling the voicecoil's ouput, the kinetic energy will continue to move the cone.
If you consider the high advertised DF numbers, the amp's output impedance must be very small. This is achieved by negative feedback. For some reason negative feedback has become a bad word in audio circles but in my opinion it's a very good thing. When a speaker continues to oscillate after a note has passed the voltage generated by the moving voicecoil is fed back into the input of the amp, only reversed in polarity. Hence the name negative feedback. The amp then induces a current opposite to the one generated by the voice coil causing cancellation in an effort to reduce the cone's motion to zero. In reality the amp does not have an iron grip on the coil's motion. The electrical control is "loose" and the kinetic energy of the moving mass dominates the system.
This is the reason why damping factors over ~200 are nice, but not something to pay extra for. Two hundred is not a magic number but above this point we are getting well into the region of deminishing returns. No matter how good the amp is at cancelling the voicecoil's ouput, the kinetic energy will continue to move the cone.
02-15-2009, 09:02 PM
#16
The spec is derived by: speaker impedance / amp output impedance. The simple story is that the amp "shorts" the ouput of the voicecoil when it tries to move contrary to the amp's ouput signal. Since the coil is in a magnetic field it will generate a voltage proportional to it's velocity. If it is not moving in agreement with the music program the amp will short this voltage and sap the excess energy. That's the semi-accurate over-simplified description.
If you consider the high advertised DF numbers, the amp's output impedance must be very small. This is achieved by negative feedback. For some reason negative feedback has become a bad word in audio circles but in my opinion it's a very good thing. When a speaker continues to oscillate after a note has passed the voltage generated by the moving voicecoil is fed back into the input of the amp, only reversed in polarity. Hence the name negative feedback. The amp then induces a current opposite to the one generated by the voice coil causing cancellation in an effort to reduce the cone's motion to zero. In reality the amp does not have an iron grip on the coil's motion. The electrical control is "loose" and the kinetic energy of the moving mass dominates the system.
This is the reason why damping factors over ~200 are nice, but not something to pay extra for. Two hundred is not a magic number but above this point we are getting well into the region of deminishing returns. No matter how good the amp is at cancelling the voicecoil's ouput, the kinetic energy will continue to move the cone.
If you consider the high advertised DF numbers, the amp's output impedance must be very small. This is achieved by negative feedback. For some reason negative feedback has become a bad word in audio circles but in my opinion it's a very good thing. When a speaker continues to oscillate after a note has passed the voltage generated by the moving voicecoil is fed back into the input of the amp, only reversed in polarity. Hence the name negative feedback. The amp then induces a current opposite to the one generated by the voice coil causing cancellation in an effort to reduce the cone's motion to zero. In reality the amp does not have an iron grip on the coil's motion. The electrical control is "loose" and the kinetic energy of the moving mass dominates the system.
This is the reason why damping factors over ~200 are nice, but not something to pay extra for. Two hundred is not a magic number but above this point we are getting well into the region of deminishing returns. No matter how good the amp is at cancelling the voicecoil's ouput, the kinetic energy will continue to move the cone.
Thank you for the simplified version of how it could work. I was wondering why my Helix amp has a variable damping factor up to 800. It makes sense now.
Buy the DD!
02-16-2009, 01:31 PM
#17
Guest
Posts: n/a
we sold dd amps until they dicked over half of canada......we had 8 amps, sold them all.....5 broke(one was d.o.a.) and one took aver a year to fix and it was by far the most painful experience dealing with any company ever....i could not encourage you to try any other product than dd......they averaged a mamoth failure rate for me, i think nothing more need be said.....except that they are utter dogcrap and should be avoided at all cost as its not a mater of if its going to fail on you but when
02-16-2009, 01:42 PM
#18
Hey Dave I can see that you have a bad taste in your mouth from the whole "Modz" experience, but I gotta tell you that the 5 series subs the "A" series amps, some of the "C" series amps are made in China and they suck ***** for reliability. The rest of their stuff blows my mind...and my load! They found a great build house in Korea that bulletproofs their stuff. All of the non-5 series subs are made in Oklahoma. Their components are made in Germany.
Since you've had them, they've grown in a positive way and I've paid the price by selling their jusk and having to warranty it at my expense. Now that I don't purchase the crap, I'm making profit and gaining happy customers.
Since you've had them, they've grown in a positive way and I've paid the price by selling their jusk and having to warranty it at my expense. Now that I don't purchase the crap, I'm making profit and gaining happy customers.
02-16-2009, 08:31 PM
#19
Guest
Posts: n/a
sorry but there is nothing that dd makes that i will ever use in my life ever again......and to the guy that said that he would use a dd over an audison has missed his calling......he should have been a comedian......its a little known fact that korea is the hotbed of amplifier manufacturing.......not italy
