Sure; according to my preferences speaker & amp are always a system.
I once made a bridged output amp with a negative output resistance using...
...microphone transformer.
Should I patent it, huh?
My point was not in who should claim patent right. I agreed with Joachim Gerhard that close to zero ohm output resistance is pointless for damping: if you want to damp speaker cone in physical reality use negative output resistance, otherwise all that damping factor it is a nonsense, though wide accepted as something real. I suppose it was invented by Japanese marketing departments back then when they were killing American and European audio electronics.
We seem to be drifting away from 'calibration mikes'. There have been many man-years devoted to their development by B&K and earlier sources. It is difficult, but understandable, and effectively repeatable with real understanding of what you have, if you have a calibration quality microphone. In this case, comparing the calibration microphone to another cheaper, or at least different, microphone, can give the user a reasonably accurate measurement as to what the different microphone does with frequency. However, there are a few 'pitfalls' due to the nature of microphones, themselves, relative to on axis and off axis response, even with omni microphones.
To understand this is more important than quibbling about calibration procedures with piston-phones and some such.
To understand this is more important than quibbling about calibration procedures with piston-phones and some such.
And than what about this?
http://www.diyaudio.com/forums/anal...ch-preamplifier-part-ii-1937.html#post2825059
Joachim,
Approximately 20dB (IIRC) improvement in terms of BL(i) distortion over ferrite. BTW, Nd is better than ferrite magnets in this context, but to a lesser degree. Ferrite magnets are really horrible.
Back in East Germany there where Schulze/EAW KSP215 with both ferrite and Alnico magnets, measured essentially identical efficiency and FR (they where really interchangable in the Studio Enclosures that included an Amplifier and EQ network while continuing to meet the spec. The Alnico versions however sounded rather different (some may say better) and we tended to hoard them for personal use.
There was a similar story for the old east-german 12" "zwoelfeinhalber", a 12.5W rated full range driver. Despite measuring essentially identical the earlier Alnico/cast frame version where much preferred to the later ferrite magnet/stamped frame versions.
Yup. But don't tell that to any of the amplifier designers here, who like to pile on an extra 40dB feedback just to be able to claim a four figure DF...
Ciao T
Approximately 20dB (IIRC) improvement in terms of BL(i) distortion over ferrite. BTW, Nd is better than ferrite magnets in this context, but to a lesser degree. Ferrite magnets are really horrible.
Back in East Germany there where Schulze/EAW KSP215 with both ferrite and Alnico magnets, measured essentially identical efficiency and FR (they where really interchangable in the Studio Enclosures that included an Amplifier and EQ network while continuing to meet the spec. The Alnico versions however sounded rather different (some may say better) and we tended to hoard them for personal use.
There was a similar story for the old east-german 12" "zwoelfeinhalber", a 12.5W rated full range driver. Despite measuring essentially identical the earlier Alnico/cast frame version where much preferred to the later ferrite magnet/stamped frame versions.
Yup. But don't tell that to any of the amplifier designers here, who like to pile on an extra 40dB feedback just to be able to claim a four figure DF...
Ciao T
Voice coil resistance is an inevitable part of the speaker equivalent circuit. Depending on Re and speaker mechanical impedances (with box included, acoustical impedances transferred to membrane), we may get underdamped, overdamped or optimally damped responses. This should be a part of speaker and cross over design. Adding resistor between speaker and amplifier or using negative impedance is incorrect.
Pavel,
If you want an amplifier that all possible speakers out there it would need adjustable output impedance.
I know some speakers that are designed to be used with amplifiers having relatively high Z-Out and ones that due to design flaws have a major overblown bass unless some negative impedance is applied.
In the end, negative or positive output impedance and how much is another tool a designer may (or may not) wish to employ to get a certain result. To call their use "inaccurate" is what I would call inaccurate...
Ciao T
If you want an amplifier that all possible speakers out there it would need adjustable output impedance.
I know some speakers that are designed to be used with amplifiers having relatively high Z-Out and ones that due to design flaws have a major overblown bass unless some negative impedance is applied.
In the end, negative or positive output impedance and how much is another tool a designer may (or may not) wish to employ to get a certain result. To call their use "inaccurate" is what I would call inaccurate...
Ciao T
strange assertion - magnet manufacturer's catalogs, tech papers claim Ferrites are much more linear source of flux than
AlNiCo
Ferrite recoil BH curves only become nonlinear at low B operating, well below BH optimum, maybe you just saw poorly sized isotropic "Grade 1" Ferrite
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Hi,
Not sure we are discussing the same effects. What I remember was a source (possibly Ragnar Lien) who had made these comparison and posted the curves.
The upshot was that alnico magnets showed much less BL(i) variation than Ferrite and Nd showed somewhat less BL(i) variation than plain old ferrite.
Maybe I can also find that issue of MJ where they tested different Tannoy Drivers for distortion, Alnico measured better than ferrite...
Ciao T
Not sure we are discussing the same effects. What I remember was a source (possibly Ragnar Lien) who had made these comparison and posted the curves.
The upshot was that alnico magnets showed much less BL(i) variation than Ferrite and Nd showed somewhat less BL(i) variation than plain old ferrite.
Maybe I can also find that issue of MJ where they tested different Tannoy Drivers for distortion, Alnico measured better than ferrite...
Ciao T
Yeah, but since most speaker loads are not linear adding output resistance to an makes the overall output less linear - kills damping factor of course. Most of what I've heard from others is that adding output resistance hurts sound quality.
One should read the paper very carefully. The method is pretty different from a mere placement of series resistor behind the amplifier output.
High output impedance of power amplifiers, as seen in many tube amps, IS a bad thing. It will create frequency response with dips and bumps related to speaker impedance curve, and change Q of the bass driver. Sometimes it works like a sort of tone controls. Some may like it, I understand, but it has nothing to do with sound fidelity.
Not when either the input-impedance of the loudspeaker(system) is ruler-flat,
or the interaction between the high(ish) output-impedance of the amplifier and the non-linear input-impedance of the loudspeaker counteracts a non-flat frequency-response of the loudspeaker.
Non-linear frequency-response can also be corrected before the amplifier,
if the amp-loudspeaker combo are designed as a system.
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