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Damping factor of SE84CS (Read 5029 times)
hdrider
Ex Member



Damping factor of SE84CS
01/03/06 at 15:49:48
 
What is the damping factor of the Zen SE84CS amp? is it considered high or low? I have been looking at Martin King's site about building a cabinet for my fostex FE206's and the correction curcut mentions this, did not see it on the spec sheet for my amp. Thanks, hdrider.
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veryoldcat
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Re: Damping factor of SE84CS
Reply #1 - 01/03/06 at 18:29:43
 
hrider,

The damping factor would be considered fairly low. As to just HOW low, I'm not sure, but certainly under 10 (guessing); perhaps there's someone around here that knows exactly.

Karl
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BWR
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Re: Damping factor of SE84CS
Reply #2 - 01/04/06 at 03:55:59
 
According to the specs, the SE84C has an output impedance of 0.8 ohms (at what frequency is not specified). The damping factor is typically defined to be the ratio of an 8 ohm speaker load to the output impedance. Thus, the damping factor is: 8 ohm / 0.8 ohm = 10.

Output impedance usually varies with frequency, so the damping factor will also vary.

Hope this helps,
Bob
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veryoldcat
Ex Member



Re: Damping factor of SE84CS
Reply #3 - 01/04/06 at 06:39:21
 
Nifty, BWR,

So, where did you find the output z of the select?

(Just curious)

Karl
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BWR
Ex Member



Re: Damping factor of SE84CS
Reply #4 - 01/04/06 at 16:07:29
 
[quote author=veryoldcat  link=1136306988/0#3 date=1136356761]Nifty, BWR,

So, where did you find the output z of the select?

(Just curious)

Karl [/quote]

I found the output z of the SE84C (not the select) on the specifications page. I assume that the Select version is the same.
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chrisby
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Re: Damping factor of SE84CS
Reply #5 - 01/09/06 at 19:38:21
 
Don't forget there may other numbers to plug into the damping factor equation than just the "output impedance" of ANY amp

For a reasonably concise explanation, check out post #8 page 2 of:

http://www.audiocircle.com/circles/viewtopic.php?t=24501

( for those of you that don't already have that page saved on your favorites!)
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BWR
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Re: Damping factor of SE84CS
Reply #6 - 01/10/06 at 03:34:24
 
[quote author=chrisby  link=1136306988/0#5 date=1136835501]Don't forget there may other numbers to plug into the damping factor equation than just the "output impedance" of ANY amp

For a reasonably concise explanation, check out post #8 page 2 of:

http://www.audiocircle.com/circles/viewtopic.php?t=24501

( for those of you that don't already have that page saved on your favorites!) [/quote]

I guess I missed it. The author specifically cites output impedance as the determinant of damping factor. From the 4th paragraph: "The lower the plate resistance, the lower the output Z. The lower the output Z, the higher the damping factor. The higher the DF, the better the bass performance (in most cases)." The whole notion of damping factor is misleading for two reasons: no speaker is a fixed 8 ohm load and an amp's output impedance is a function of frequency. So the damping factor is constantly changing as the input signal.

-- Bob

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DirtDawg
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Re: Damping factor of SE84CS
Reply #7 - 01/10/06 at 04:58:31
 
[quote author=BWR  link=1136306988/0#6 date=1136864064].......... The whole notion of damping factor is misleading for two reasons: no speaker is a fixed 8 ohm load and an amp's output impedance is a function of frequency. So the damping factor is constantly changing as the input signal.

-- Bob

[/quote]

Yes, I agree. So, do you start with a theoretical DF as high as possible and hope for the best or simply choose speakers that are well damped mechanically and be satisfied? Or maybe listen and not worry about it too much? ;D
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chrisby
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Re: Damping factor of SE84CS
Reply #8 - 01/10/06 at 19:52:05
 
[quote author=BWR  link=1136306988/0#6 date=1136864064]

I guess I missed it. The author specifically cites output impedance as the determinant of damping factor. From the 4th paragraph: "The lower the plate resistance, the lower the output Z. The lower the output Z, the higher the damping factor. The higher the DF, the better the bass performance (in most cases)." The whole notion of damping factor is misleading for two reasons: no speaker is a fixed 8 ohm load and an amp's output impedance is a function of frequency. So the damping factor is constantly changing as the input signal.

-- Bob

[/quote]


The final sentence of the cited paragraph, and the first sentence of the following:

Quote:


" So in a single ended amp, the DF flip flops on the fly with the plate swing. In a PP amp, one tube's current is swinging high while the other swings low, which yields a constant average of the two."




The point I was attempting to make by the above quote, and on which I think we agree, is that DF is one of those spec's that mean a lot less than they might, in the real world.

i.e. the range of potential speaker & interface impedance  (combination of  R + I +C) is so wide, that it's probably meaningless to quote DF for any amp ( and specifially a SE ) except at a fixed impedance and frequency.  Since the music / loudspeaker interface present far more complex a load than that (think of is as a type of global feedback), it (DF) alone can't necessarily predict the sonic outcome.  Some listeners use high DCR speaker wire  specifically for the purpose of altering the "loudspeaker  Q / amplifier DF" equation to their taste.

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chrisby
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Re: Damping factor of SE84CS
Reply #9 - 01/10/06 at 19:54:27
 
[quote author=DirtDawg  link=1136306988/0#7 date=1136869111]

Yes, I agree. So, do you start with a theoretical DF as high as possible and hope for the best or simply choose speakers that are well damped mechanically and be satisfied? Or maybe listen and not worry about it too much? ;D
[/quote]


I opt for the latter - there's already too much thinking getting in the way of the temporary sensory escape I'm asking my music to give me.
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« Last Edit: 01/10/06 at 19:55:06 by chrisby »  
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Brian
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Re: Damping factor of SE84CS
Reply #10 - 01/13/06 at 05:49:00
 
Hi hdrider, Welcome to the forum.  
Here are some numbers to put "high" & "low" DF into perspective.
For a zero negative feedback SET, a DF of 6 is very high, and many have a DF of around 2 or 3.  A high-feedback Push Pull tube amp may have a DF of 15 (NFB lowers the output Z), and a high-feedback PP Solid State amp may have a DF of anywhere from 100 to around 2000.  

Generally it is said big 15 & 18 inch woofers of the high moving mass kind are the speakers that require a strong damping factor.  I would think that your fostex FE206 would sound great with any amp so far as DF is concerned.  
The Zen SE84CS even sounded great handling a 15" driver at the recent Decfest when that 15 was mounted in the Imperial horn cabinet.  Apparently horn loading helped control the driver movement.
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veryoldcat
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Re: Damping factor of SE84CS
Reply #11 - 01/13/06 at 07:05:11
 
[quote author=Brian  link=1136306988/0#10 date=1137131340]Hi hdrider, Welcome to the forum.  
Here are some numbers to put "high" & "low" DF into perspective.
For a zero negative feedback SET, a DF of 6 is very high, and many have a DF of around 2 or 3.  A high-feedback Push Pull tube amp may have a DF of 15 (NFB lowers the output Z), and a high-feedback PP Solid State amp may have a DF of anywhere from 100 to around 2000.  

Generally it is said big 15 & 18 inch woofers of the high moving mass kind are the speakers that require a strong damping factor.  I would think that your fostex FE206 would sound great with any amp so far as DF is concerned.  
The Zen SE84CS even sounded great handling a 15" driver at the recent Decfest when that 15 was mounted in the Imperial horn cabinet.  Apparently horn loading helped control the driver movement.   [/quote]


I'd say Chris is pretty close, here. Much better thinking than me, but you've got to hear an amp to know!

Many MANY years ago, I tried out a Crown amp that had an amazing damping factor (a highly touted spec; maybe it was 800+, or something) and as expensive as it was, it was a total sonic washout. It was kind of pushed at me by a friend who was a well known recording studio engineer tech, etc of the 70's here in SF. It was one of the worst sounding pieces of gear I'd experienced. Gave it back gracefully, but IMMEDIATELY.

At the time, I compared it to a McIntosh mc-225, and there was no contest whatever, specs notwithstanding.

Caveat emptor.

Karl
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Brian
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Re: Damping factor of SE84CS
Reply #12 - 01/14/06 at 03:29:35
 
Hi Karl,  That assesment sure agrees with what Obi-Vaughn used to tell me about damping factor.  A little is good but more is not necesarily better.  An increase in DF improves control of the bass, but can strangle the life out of the music.
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teepeeworks
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Re: Damping factor of SE84CS
Reply #13 - 01/18/06 at 04:19:41
 
I agree after reading many of Eddie's posts I have saved. He specifically mentions on 2 different occasions that basically a single, full-range driver mates best or takes advantage of a tube amps LOW damping factor. The way he worded it, I got the impression that when using full range drivers the lower the better. I should go through his posts and try and find exactly what he says. Needless, I am not concerned about the issue.

Take care,

Corey
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selmerdave
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Re: Damping factor of SE84CS
Reply #14 - 01/18/06 at 13:29:06
 
[quote author=Brian  link=1136306988/0#10 date=1137131340]Generally it is said big 15 & 18 inch woofers of the high moving mass kind are the speakers that require a strong damping factor. [/quote]

I'm guessing that this is also a function of the speaker motor.  For example, my Altecs are very highly damped due to a very large magnet, so I would think they require less damping factor from the amp than a smaller-magnet 15".  

Dave
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« Last Edit: 01/18/06 at 13:30:00 by selmerdave »  
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