Many thanks Allen_Shore for the graphs. These will be very helpful as references.
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Many thanks Allen_Shore for the graphs. These will be very helpful as references.
I found Allen's graphs interesting mainly because of the contrast between them and the ones done by Zilch and posted at AudioKarma. Zilch's graphs showed the Altec horns to have a frequency response like a rollercoaster and rolling off at around 7KHz, being around 10dB down at 10KHz.
Allen's graphs are quite different.
Turntable : Yamaha GT 2000 - Cartridge : Soundsmith The Voice Ebony - Phono Stage : Moon LP5.3 - Preamp : Transcendent Sound Grounded Grid - Speakers : KRK Expose E8B.
Weren't they of the 806, which indeed is a much poorer performing driver compared to the 802, 902 series?
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Turntable : Yamaha GT 2000 - Cartridge : Soundsmith The Voice Ebony - Phono Stage : Moon LP5.3 - Preamp : Transcendent Sound Grounded Grid - Speakers : KRK Expose E8B.
Don't recall those nor the resolution they were measured at, which can make them look somewhat different, not to mention driver condition, especially the AlNiCo ones.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Why would you measure below 300hz? Seems like it would be easy to damage them.
Can you detail your test setup for us?
And, because I'm lazy, what is the MR931? The little guy used on the model 14?
Edit: I went and looked...I never did like those.
I have a pair of MR994 that I like quite well but have never really built into a system for critical evaluation. Small format 500hz, they are huge!
Ron
Last edited by RonSSS; August 18th, 2012 at 10:39 AM.
Enjoying Altec Speakers since 1972
Thanks for the plots, very nice reference.
As a long time user of HOLMImpulse here are some tips to give you cleaner results:
- Keep the volume up. It looks like you are not running these very loud, at least not compared to the noise floor. You want a good S/N ratio.
- Use the high pass filter. If you look down just to the left of the impulse window, you'll see High Pass and Low Pass filters. For horns and drivers, a 200Hz HP is a good idea. No low frequencies going into the driver and HOLM won't pick up junk down there
- You can start your sweep at 100Hz or higher. That's in the first tab. It's handy, but the high pass filter is the real tool you need.
I'm a little surprised to see how similar at least two of plots are. That's encouraging.
Here's a more critical vertical scaling ( of Alien's measurement ) to compare to Zilch(s) work ;
- Zilch ( in his time ) measured a few Altec 802s & 902s on both 811s & 511s .
- He also started to keep track of diaphragm models when it became apparent that various combos of diaphragm/phase-plugs made a difference ( & if he didn't, then I did ) .
- Gallery
And the ( 9-slit radial ) GPA version of the 802G ( not EQed ) .
Last edited by Earl K; August 19th, 2012 at 08:22 AM.
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