BillFitzmaurice.info

CaseFAceMcGee wrote:Dad Gummit - so close! I think the woofer slap is taken care of, but I can't tell because the mid driver slaps more than the three stooges when I turn it up.

It shouldn't, even at full power excursion will be no more than a millimeter if the crossover is correct.

CaseFAceMcGee wrote: I think the woofer slap is taken care of, but I can't tell because the mid driver slaps more than the three stooges when I turn it up.

Uh-oh. Either the grill is vibrating or the xover may be wired wrong.

It wouldn't surprise me if the crossover wasn't quite right, I'll probably be able to check it tomorrow.

The cab worked great at rehearsal. I am in a swing band, competing against 5 trumpets who all think they are playing 1st My Little Mark III was set with gain and master volume just over 9:00, and it was plenty of volume.

http://s301.photobucket.com/albums/nn68 ... 0pictures/

Getting two new hurricane nuts today - I managed to mess up the threads. The grill should be built in the next few days.

Edit: also getting different 1" screws for the top handle and wheels - wood screws look funny there.

I spent some time tracking down the buzzing that I heard, and as far as I can tell the mid driver is fine. The two side handles, on the other hand, were buzzing like crazy. I took them off for now, to find other noises they may be covering up, and I've gotta figure out how to eliminate their rattling.

Now I can hear that the tweeter is either buzzing or distorting... it seems to happen almost exclusively in the lowest two octaves of my 5-string - the lower I go, the worse the sound is. How would I be able to figure out if the tweeter is distorting?

On the plus side, when the volume is down low enough to avoid the tweeter madness, it sounds like butter.

Cross-over problem, again. If you are playing a note lower than the band-pass of the tweeter, it's a cross-over issue. Triple check the wiring and the mid to high crossover.

Thanks, that's a task for tomorrow or Thursday. Is there a way to tell if I fried a cap or coil or something? I did a cursory check of the crossover today and didn't see any issues, so next chance I get I'll make a schematic just from looking at my crossover and compare it to the one in the plans.

CaseFAceMcGee wrote: Now I can hear that the tweeter is either buzzing or distorting... it seems to happen almost exclusively in the lowest two octaves of my 5-string - the lower I go, the worse the sound is. How would I be able to figure out if the tweeter is distorting?

Disconnect it. I bet it's not sealed well enough to the cab and is vibrating.

I had a huge post that I had typed up over the course of my diagnostics, almost complete, when FireFox decided that it would be a good time to crash and lose all of it. Hopefully I remember to include all the important stuff...

This revamped version is brought to you with help from Pulp Fiction and Jim Beam.

Bill Fitzmaurice wrote:Disconnect it. I bet it's not sealed well enough to the cab and is vibrating.

I tried that, no dice. The buzzing is coming from the tweeter, and the mid driver also. I double checked the crossover wiring, and I found nothing that didn't appear to match up with the schematic in the plans. I checked all wires to make sure the negative was actually the negative, and same with the SpeakOn cable - no issues found.

My wiring setup has a few feet of speaker wire running from the SpeakOn toward the crossover. Three 8-inch wires connect to this jumper wire, then connect to the three crossover sections. The crossover sections connect to the speakers through equal-length wires, about 4 feet each.

I'm pretty much out of ideas as to what's going on with it The only thing that I can think of is crosstalk between the crossover components or the speaker wire, but I don't know if that would cause this much of an issue. The speaker wires do get very close in spots due to my current wiring configuration - I've been planning on running the wires more cleanly once everything is working properly. The distortion only happens in the lowest register, the lower I go the worse it gets, and it is very noticeable at the start of a note with the amp at about 40% volume and 40% or less input gain. The input is not clipping. I have also gotten the distortion while running a sine wave, 100hz, from my laptop through the amp. As I said, the noise is in the tweeter and the mid driver. I did not notice any distortion in the woofers.

And like I said, if you are hearing 100Hz through the mid or HF driver, you have a crossover problem.

The crossover's job is to send the correct frequencies to the correct driver. 100Hz should be 100% to the woofer. If you get it in the mid driver, or the HF driver, there is a problem with the crossover. Take pictures of the crossovers and wiring and post them so we can spot any problems. BTW, it may be a bad component in the crossover.

You were right DJPhatman, it is definitely a crossover-related issue, but for the life of me I can't figure out where. I have three crossover pictures here that show the crossover and the mess of wires currently surrounding it. I would throw together labels in MSPaint, but I've gotta be at work in less than 8 hours and I still need to shower and cook supper. Crossover sections are Low-Mid-High from top to bottom in all pictures. Tomorrow I can pull the crossover from the cab and make a labeled picture of it.

CaseFAceMcGee wrote:You were right DJPhatman, it is definitely a crossover-related issue, but for the life of me I can't figure out where..

No surprise that, with all that stuff on one board. That's why I recommend that each filter be mounted on its own board, so that you're less likely to get confused with all the components and wires.

Bill Fitzmaurice wrote:No surprise that, with all that stuff on one board. That's why I recommend that each filter be mounted on its own board, so that you're less likely to get confused with all the components and wires.

That's one change that I plan on making - splitting up the three boards, mounting them separately. I went off the layout for another board that I found on this site, but mine apparently didn't work out as well.

CaseFAceMcGee wrote:

Bill Fitzmaurice wrote:No surprise that, with all that stuff on one board. That's why I recommend that each filter be mounted on its own board, so that you're less likely to get confused with all the components and wires.

That's one change that I plan on making - splitting up the three boards, mounting them separately. I went off the layout for another board that I found on this site, but mine apparently didn't work out as well.

Or, better yet, have Leland make it for you. I'm sure he'd be glad to, plus he'll probably test it before he sends it to you. Worth the price, IMVHO.

DJPhatman wrote:Or, better yet, have Leland make it for you. I'm sure he'd be glad to, plus he'll probably test it before he sends it to you. Worth the price, IMVHO.

I was considering that when I ordered the parts, but I thought I would save a few bucks and learn something by doing it myself... my guess is my awesome soldering skills were too awesome for a few of the caps. After I'm done with work and a much-needed bike ride today, I'll be (carefully) desoldering the connections, which I'm guessing will resemble this , then if my multimeter cooperates I can hopefully diagnose whether I've got some dead components.