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Damping factor (Read 4015 times)
Ned
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Damping factor
07/26/16 at 22:01:54
 
I'm wondering what the damping factor is for this amp. Is this the right place to ask? That spec isn't given on the Rachael web page.
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Lin
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Re: Damping factor
Reply #1 - 07/27/16 at 14:22:19
 
It would be low because: ZERO negative feedback used

http://www.butleraudio.com/damping1.php
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hdrider
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Re: Damping factor
Reply #2 - 07/27/16 at 19:12:22
 
Good question and it never crossed my mind when I ordered our Rachael amp. I kind of gave up on the spec game when I proved to myself that Steve's Zen path was the way to go for us. George Augspurger is a well known name in acoustics/pro-sound world and I think he knows of what he speaks. I can vouch for the fact that our Rachael drives and controls our Omega 7XRS amazingly well. As a bassist I am a little OCD on the amount, tone and texture of that end of the spectrum. What speakers are you thinking of driving with a Rachael? Happy listening, Chris.
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Rachael, ZP3, ZMC 1, SE84CS, Oppo BDP-93, Sota Star TT w/ FR-64, Shinnon Red Moving coil, Omega 7XRS Mk 2 walnut, DeepOmega 8 sub, Morrow Audio PH3 and MA3 IC's, Stax Lambda Signature Pro & SRM-T1 tube amp, Gamma Electrostatic phones.
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Denizen
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Re: Damping factor
Reply #3 - 07/27/16 at 19:44:20
 
And output transformers, so low damping factors.
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Ned
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Re: Damping factor
Reply #4 - 07/28/16 at 00:49:18
 
I realize it will be low, even very low because of zero negative feedback. It may also relate to the output transformer and factors related to it, among other things(such as the resistance of the speaker cables). But is the damping factor for the Rachael known? Could it be as low as 2 or 3?

The reason I ask is that I recently have been assembling a system. It isn't all the way there yet but the Rachael is the amp. The speakers are a custom build of the Musical Affairs Mini Baffle. This is a 1.5 way speaker using modified EMS LB12EX wideband field coil drivers with a MA5EX tweeter to augment the high end. It is a about 95-96 db efficient.

I noticed that bass performance was a bit lean. Part of that could attributed to break in for the drivers. Just to check it out, I connected an old NAD 7150 50 wpc receiver to how the sound was different. First thing I noticed besides the minimal amount of turn the volume knob allowed before getting way too loud was the bass was much better. Of course there were other differences too regarding the overall character of the sound  but that wasn't the point.

I asked a very highly respected builder of SET amps about it and he offered that the difference in bass performance could be related to a damping factor so low that the amp wasn't able to get the driver to deliver full bass. He told me many of his clients believe they need more watts to achieve proper bass when it really is that they need an amp with a bit more damping. Usually obtained by use of better OPTs.

It may just be that this amp and these speakers just are not an ideal match. No fault of either component, not all amps and speakers can be expected to work equally well together.

I think Omega designs are a better match up with Decware SET amps. The drivers used are apparently more forgiving of very low damping it seems.

I may be needing to do some further system changes.

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Lin
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Re: Damping factor
Reply #5 - 07/28/16 at 02:32:20
 
Where do you have the drivers voltage setting at?
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Ned
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Re: Damping factor
Reply #6 - 07/28/16 at 04:03:23
 
The field coil power supplies (one for each speaker, powering both drivers) come with the speakers. They're preset at 12.4 volts and aren't variable.
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Lin
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Re: Damping factor
Reply #7 - 07/28/16 at 19:13:16
 
Are your speakers open baffle or horns?
At 12.4 volts the drivers qts is in the low 0.2 range which is horn territory.
I would want to run them in the 6 to 5 volt range for a qts above 0.5* for open baffle speakers.

*unless using eq and much more power
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Re: Damping factor
Reply #8 - 07/28/16 at 20:49:25
 
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Ned
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Re: Damping factor
Reply #9 - 07/29/16 at 06:18:02
 
Yes, open baffles. An updated take on the Wharfedale SFB/3. What I have is a bit different from the one on their website.

Actually I have the field coil voltage wrong. The power supply for both drivers (beside the speaker to the lower left of the picture) has a readout. Without ever looking closely, I thought it was displaying 12.4. However, I just took a closer look and their is no "point", so it's reading 124. Also it powers two different drivers, so that readout may be the combined voltage going to both and it doesn't seem to give separate readings for what each one is getting.

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« Last Edit: 07/29/16 at 06:34:54 by Ned »  
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Lin
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Re: Damping factor
Reply #10 - 07/29/16 at 19:36:24
 
I don't know where you are at, but 124 sounds like it could be your wall voltage?
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« Last Edit: 07/29/16 at 19:38:42 by Lin »  
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Ned
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Re: Damping factor
Reply #11 - 07/29/16 at 20:23:04
 
I'm in California, so yes it could be the wall voltage. And the readout does seem to float between 123 to 126 over time. So, I can't say what voltages the field coils get. They get what the builder determined to be optimum for performance/sound quality.
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Lin
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Re: Damping factor
Reply #12 - 07/29/16 at 20:43:08
 
Good because 12.4 had me scratching my head. Smiley

Still don't understand why the NAD would give you more bass, more controlled bass yes. Undecided

Too bad the voltage isn't adjustable to some degree, I could see where that would be helpful with different amps. Cool
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« Last Edit: 07/29/16 at 20:46:11 by Lin »  
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Ned
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Re: Damping factor
Reply #13 - 07/29/16 at 23:28:18
 
Two possible ways I can think of that might combine to make a difference in lower bass. One is the flatter more linear response curve the SS amp should have, the SET probably drops off a few db down low. The other is that better control may allow for better articulation of low frequencies making them a bit more audible. Either factor alone, might not make much audible difference, but in combination they could be causing some diminishment of low end response.

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Re: Damping factor
Reply #14 - 09/24/16 at 03:01:45
 
In my experience a lower damping factor usually means more bass because the cone moves more (higher x-max at resonance). It is not until the power exceeds the compliance of the speakers' suspension that the lack of damping is ever a problem. Once the power level is at that point for a given speaker driver in a given box or baffle, then having a damping factor greater than zero will allow the speaker to play louder without distortion. So if the speaker has to be played loud to too have bass, then some damping would be desirable. If not, then damping will result in less bass.

The SE34I.5 is a triode wired pentode(EL34) or beam tetrode (6L6) amplifier that by being wired as triodes have linear output into all impedances making the damping greater than zero. The SE34I.5 into 8 ohms is about 5.7 damping factor. Of course there is the inconvenient truth that a speakers resistance rises and falls through it's frequency response. At resonance the speaker is more likely to be around 30 ohms not 8 ohms.  At 30 ohms the damping factor would rise to between 15 and 21 depending on what position you had the speaker impedance switch set to. Another inconvenient truth is that this simple formula only works with pure resistance, and both the amplifier and the loudspeaker have impedance which is to say resistance, capacitance and inductance. That makes reality 36 times more complicated than the damping formula can predict.

Please read the following excellent explanation:


Click here for a great  explanation of damping factor and speaker relationships.

Steve


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4krow
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Re: Damping factor Division
Reply #15 - 09/30/16 at 17:57:36
 
Steve,

Thank you for a more concise and accurate response to this question so that I can get a better grasp of damping factor as it applies to cone movement. Now complicated as it gets, I'm afraid that there is more to it as it applies to the FRX2 drivers running off of the 34.5i. As you mentioned the 34.5i has an impedance switch that will change the calculation, but then so does the FRX2! In fact, the two settings of the driver determine it's load to the amp in the first place...am I concluding this correctly? At first thought, I would consider all of this to be a more stable load to the amp in the first place....Your thoughts...
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Decware 34I.3 integrated amp/Forte' 3 bass amp/Velodyne SMS-1 bass mngmnt system/Decware ZOB speakers/BESL subs/Emotiva ERC3 CD player/BPT 3.0 power cond. PS Audio P500
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