| theory meets "reality" in the living room [message #37222] |
Tue, 09 July 2002 07:34  |
Sam P.
Messages: 307
Registered: May 2009
|
Grand Master |
|
|
Was playing with the old sig gen, and decided to repeat a series of level checks where the effect of varying the size of the xover series resistance "bypass" cap was examined. With no bypass cap installed, shorting the series R only boosted output by 10dB, so any "gain" provided by the cap can't exceed that amount.
I was interested in performance enhancements at 10kHz. and 15kHz.cap 10kHz. 15kHz.
0.33 +1dB +3dB
0.47 +2dB +4dB
0.68 +3dB +6dB
1.0 +4.5dB +8.5dB measured on axis, at 1 meter. Maybe this explains why I could hardly hear any difference with/without the 0.33uF cap in use! YMMV. Sam
|
|
|
|
| Re: theory meets "reality" in the living room [message #37224 is a reply to message #37222] |
Tue, 09 July 2002 08:42  |
Adam
Messages: 419
Registered: May 2009
|
Illuminati (1st Degree) |
|
|
|
Sam... I share the same thoughts on the 0.33 uf cap... I couldn't tell the diff, either. I always thought a larger cap value would work better, but I never tried it. Between the psd2002 natural rolloff, and the biradial horn characteristics, do you think the 1 uf would be most appropriate? Adam
|
|
|
|
| best to "run the series" [message #37228 is a reply to message #37224] |
Tue, 09 July 2002 09:33 |
Sam P.
Messages: 307
Registered: May 2009
|
Grand Master |
|
|
and verify the effect "in your circuit, with your drivers". I was playing with some Altec 902's, with non-standard 35480 diaphrams.
They roll off a little sooner than my favored 34647 diaphrams, but are a little flatter across the main operating range. Now comped with 1.0uF, the meter is more or less "flat" in room at 12 feet when flipping from 100 to 1000 to 10,000Hz. (-2db). At above 15kHz, the HF driver is on it's own response wise, since the only "boost" available is already in use by then...well, you know, the 10dB lost in the series R has been "reclaimed". Honestly, I think Wayne's PSD2002 comp works FINE with 0.33 or 0.47uF and 12dB of pad in my quasi-4 Pi Pro's. IIRC, the 0.47uF Dayton I installed across the 23.5ohm series R (a pair of 47ohm Mills) may even have been a little "too hot" at the upper end when measuring the system response. In retrospect, my Altec's using the 35480 diaphrams have been slightly "hf under-comped" all along, making the 4 Pi's PSD2002's sound "brighter by contrast". Well, they REALLY were playing louder up high (15kHz) than the Altecs after all:) You didn't hear that from me, shhhh. Sam
|
|
|
|
|
|
Posting Rules
Members
Search
Help
Register
Login
Get a T-Shirt!
