hurdy_gurdyman Posted November 20, 2003 Share Posted November 20, 2003 I recently lowered the output of my Heresy squawker by changing the connection on the autoformer and putting 16 ohm resistor in parallel with the squawker. I have had the P-trap on for quite a while. When I did an in-room warble tone measurement I got a 7 dB peak 6.3 kHz and at 6 dB peak at 8 kHz. These were not there with the squawker at the factory setting. Any idea what's going on? The response chart is flatter now everywhere except these peaks. Dave Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 21, 2003 Share Posted November 21, 2003 Sounds like your P-trap in not right with the resistor in there. Quote Link to comment Share on other sites More sharing options...
hurdy_gurdyman Posted November 21, 2003 Author Share Posted November 21, 2003 I'm open for opinions on how to correct it. Dave Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 22, 2003 Share Posted November 22, 2003 I don't know if I can answer that. to be sure, test the speaker without the P-trap and see what happens. Attached are curves of 2 of my Heresies run on an LMS system at a local small speaker manufacturer. The light blue is the curve with my modified crossover and a solder-terminal K-55-V and K-77-M. The darker blue is an unmodified Heresy with a spring terminal K-55-V and a K-77. The test was not in an anechoic chamber, but in a room with 15 foot ceilings and lots of boxes, with the speaker on its back on a small table in the middle of the room. Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted November 22, 2003 Share Posted November 22, 2003 John, What was your reaction when you saw those plots? Was it what you expected? What's your take on the comparative sound of the speakers? Tom Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 22, 2003 Share Posted November 22, 2003 The vertical scale may be part of the problem, because the sound is noticably different. In fact, using the pink calibration noise in my Pre/Pro, the modified version is virtually the same as my La Scalas, my goal. However, my real first rection was, "Bloody 'ell!" The speaker with the "inferior" drivers had the better curve. From then on, I haven't seen much reason the choose the K-77-M and solder-terminal -V over the others. I've never been able to hear a difference and this graph solidifies my opinion. While I'm not surprised by the roughness (it was a sine sweep), I would not make too much out of it either. The test room was not good. We should have done it outside. The comparison of one to the other is valid, though. I think the upward slope toward HF is valid and the frequencies where rolloff occurs is valid. Mr. Paul called the University 4401 a sad little tweeter. i wonder how bad they were if these are not? Quote Link to comment Share on other sites More sharing options...
hurdy_gurdyman Posted November 23, 2003 Author Share Posted November 23, 2003 I'm beginning to wonder of my 6.3 kHz (or near there) peak may be the tweeter instead of the squawker. A couple of weeks ago I moved the the T-35 tweeters from behing the baffle to front mounting. Yesterday I added a choke to the squawker to roll it off faster and the 6 kHz peak is still there. Could front mounting the tweeter cause a rise near the crossover point like that? Dave Quote Link to comment Share on other sites More sharing options...
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