BillFitzmaurice.info

The misaligned coil makes the speaker sound like a horn or wind instrument at certain frequencies. It will be nice when it's replaced.

I just took some readings in my room with an older analog RS SPL meter and these are the results I got. I think it was running all five speakers, but I don't think it really matters. What this shows is the drop off below 95 Hz. I didn't use a calibration/correction file for these, I didn't think that mattered much either. But I have to ask, does the THT still perform well at 100 Hz and not sound too boomy? I know it can do 100 Hz with plenty of loudness. I've always used it at 80 Hz because my Polk Monitors played fine down to 80 Hz (I think - I've never noticed that the didn't). I also don't know much about making SPL charts, so I'm sorry if I did this all wrong. I just set the AVR to 90 dBC at 200 Hz, and then took readings at 5 Hz intervals downward. I don't know how much power was going to the speakers. So does this mean if I play sound back at 75 dB - 80 dB that the volume at 80 Hz to 95 Hz will be flat? Or does the chart basically show that it requires more power at that 15 Hz range to drive the speakers to be flat up to 95 Hz? I just made a table in Excel with frequency and SPL with C-Weighting.

After disconnecting the driver with the bad VC the speaker definitely sounded better, but I was still getting distortion from somewhere. Music sounded pretty good during the movie, but vocals/dialogue were getting killed. It sounded fine most of the time but then the sound would get garble thrown in. Could the empty screw holes I used for keeping the cab together when I glued cause this? Also, is it possible this is part of using 1/2" plywood (Arauco)?

c weighted still falls off a bit below 100 hz though too, just pointing that out.

Ran a test tone and I think it's just the "dead" driver resonating. I didn't want to leave the baffle open so I put the driver back in to keep the cab air tight. Dang. Well, I guess I have my answer and it will just be a few days 'til my replacement drivers arrive.

sine143 wrote:c weighted still falls off a bit below 100 hz though too, just pointing that out.

Thanks, Sine. I'm not too terribly familiar with taking readings and understanding A-weight vs C-weight. The few things I've read don't explain too much. If I remember, A-weight is for middle range frequencies, maybe 500 Hz and up, maybe to 10,000 Hz? C-weight is for the entire audible range. I also remember reading that many safety ratings are with an A-weight, but C-weight seems to have become the new standard for aural safety. Please add any corrections, like I said, this is just me recalling something I don't understand very well.

He's a picture from a couple days ago, taping the tweeter holes. Since the tweeters are so small I just cut the 1/2" gasket tape about in half, down the center. It's the perfect amount for them.




Today I cut temporary covers for the two damaged woofers. Five inches is the perfect setting on the Jasper Jig. Then I marked where the mounting holes were on the driver and drilled, then drilled a counter sink for the screw heads.




All distortion I was experiencing is gone. I tested with Pink Floyd's "Money" at 90 dB and it was the clearest audio I've ever heard! These are excellent speakers. I can't wait 'til the new woofers arrive on Thursday. After that I'll just be waiting for a new plate amp for the Tuba HT. I'm not sure what PE will do, but as long as they send something that works, I'll be happy. If they hadn't been nice enough to accept it as under warranty I would have jumped on the Bash 300W amp they had for a daily deal for $99. I took a screen shot of it in my cart in case for some reason they don't want to cover the amp under warranty. So I hope that won't be the case, but if it is, then I hope they would be willing to give me the deal of the day price.

Next will have to be mini SLA surrounds. I'm thinking 3 woofers and 3 or 4 tweeters. It's probably over kill for surround duty, but at least for music it should be great.

I stand corrected by the sound of distortion. I still have one defective tweeter. It's more difficult to hear but it was creating garbled sound. It's more difficult to hear and localize it from a tweeter rather than a woofer. Hopefully PE will be as helpful as they have been and promptly send me another replacement. 24 tweeters and 18 woofers, 1/8 of the tweeters were bad and 1/18 of the woofers were bad. Compared to someone else's post I read somewhere about these drivers that this might not be too bad for buying "so many."

Does anyone know what the "impedance" of the SLAs are? I know it's variable with frequency, but I'm thinking about making high pass filters for the mains. I checked it with my multimeter and got a reading of just over 10 ohms. I used my 8 ohm Polk Monitor to make sure the adjustment dial was where it belonged, which was no adjustment/turned all the way to one direction. Does 10 ohms sound about right for a 6 woofer (8 ohms each) and 9 tweeter (8 ohms each) array? What about the center with 6 of each? I'm not sure how to add everything up using the nominal impedance numbers. I know R-series = R1 + R2 + Rn and R-parallel = 1 / (1/R1 + 1/R2 + 1/Rn). But I'm not sure how to add all these together and how to they're actually wired. I can follow the directions, but that doesn't mean I understand them.

I think my crossovers are wrong. Yes, they filter high and low, but I think they are crossing over between 1,500-1,600 Hz. That difference using the REW generator with a sin wave changes from woofer to tweeter. Perhaps this is my problem..

I disabled the woofers and ran a climbing frequency test, the tweeters reach peak low end volume around 1.8KHz - 1.9KHz. Does this sound low?

anikun07 wrote:I disabled the woofers and ran a climbing frequency test, the tweeters reach peak low end volume around 1.8KHz - 1.9KHz. Does this sound low?

Very low, by at least an octave. Either you miscalculated the component values or you miswired the tweeters, giving the wrong impedance. Or both.

I think I wired the crossovers wrong. I followed Ian's crossover with a 9.3-ohm woofer and a 5.3-ohm tweeter at 4000 Hz. I followed the wiring diagram exactly as shown with the +/- change overs where they belonged.

I checked the total resistance across the woofers (14 ohm across a single) and 9.x-ohms across the set. The tweeters (13-ohms across a single) had a total of about 13-ohms. So these sound good to me. The total resistance of the cab, across the terminals, is about 10-ohms. If there's something wrong, it has to be the crossover.