Found a new type of problem...need diagnosis.

[karl k]

The problem stems from the Peerless CSX 10 drivers I'm using in my bi-amp mains. These drivers have an exceptional sound to them until I push them a little. First, a little info on their use...

A pair of CSX 10's for each channel(L/R), in an enclosure equalling 180L in volume, tuned to 30Hz via 5"id x 9"lg port, wired in parallel for a net imp. of 4ohms, driven by a Numark Dimension 3 amp in 2ch mode w/onboard active x-over set at about 100-125Hz. Amp is rated at 475wts rms/ch at 4ohms and is 2ohm stable. Amp has clip indicators and multi segment vu meters for monitoring.

Now, Here's the deal. I hear, durring loud passages of music(rock), what would initially apear to be a sound simular to a VC bottoming out or a VC that is rubbing on the pole or mag housing. It doesn't happen all the time, with all types of music, or below certain frequencies. It's not as harsh as a VC bottoming(I have LOTS of exp. with this) and is more instantanious than a VC rubbing on the motor. It can and does happen mostly at the beginning of a bass note(as opposed to the peak of said bass note) but will also occur in greater quantity and at lower power if the x-over is raised towardes the 200Hz area. It is not a function of the box as it will occur in free air with the same power and content variables applied. I've measured the input power to the drivers as wired and the input is not exceeding the manufacturers specs. There is no sign that overheating is occurring either at the amp or the speaker and problem occurs whether listening cold or warmed up.

I've had a relative with more practical experience than I listen and he said it sounded to him like a sonic boom from a vented spider. While the CSX 10 doesn't have a vented spider, it does have a vented cone(8 holes around the parameter) above the spider and below the dust cap. Now I can close off the holes to test the theory, but if it proves to be true, what would be the long term fix without affecting heat dissipation? I'm considering foam over the holes instead of tape so air is slowed thru the holes but not stopped. It would also be "physically" possible to drill out the center of the motor for additional venting but I'm worried about chips and shavings in the VC area.

Are there any other possibilities I may be missing?

[Dual-500]

The problem stems from the Peerless CSX 10 drivers I'm using in my bi-amp mains. These drivers have an exceptional sound to them until I push them a little. First, a little info on their use...

A pair of CSX 10's for each channel(L/R), in an enclosure equalling 180L in volume, tuned to 30Hz via 5"id x 9"lg port, wired in parallel for a net imp. of 4ohms, driven by a Numark Dimension 3 amp in 2ch mode w/onboard active x-over set at about 100-125Hz. Amp is rated at 475wts rms/ch at 4ohms and is 2ohm stable. Amp has clip indicators and multi segment vu meters for monitoring.

Now, Here's the deal. I hear, durring loud passages of music(rock), what would initially apear to be a sound simular to a VC bottoming out or a VC that is rubbing on the pole or mag housing. It doesn't happen all the time, with all types of music, or below certain frequencies. It's not as harsh as a VC bottoming(I have LOTS of exp. with this) and is more instantanious than a VC rubbing on the motor. It can and does happen mostly at the beginning of a bass note(as opposed to the peak of said bass note) but will also occur in greater quantity and at lower power if the x-over is raised towardes the 200Hz area. It is not a function of the box as it will occur in free air with the same power and content variables applied. I've measured the input power to the drivers as wired and the input is not exceeding the manufacturers specs. There is no sign that overheating is occurring either at the amp or the speaker and problem occurs whether listening cold or warmed up.

I've had a relative with more practical experience than I listen and he said it sounded to him like a sonic boom from a vented spider. While the CSX 10 doesn't have a vented spider, it does have a vented cone(8 holes around the parameter) above the spider and below the dust cap. Now I can close off the holes to test the theory, but if it proves to be true, what would be the long term fix without affecting heat dissipation? I'm considering foam over the holes instead of tape so air is slowed thru the holes but not stopped. It would also be "physically" possible to drill out the center of the motor for additional venting but I'm worried about chips and shavings in the VC area.

Are there any other possibilities I may be missing?

The mains are bi-amped and the 10's run below 100-125hz????

You are not using the dual 18" sub in this system???

Sounds like one of the voice coils is delaminating from the cone or a dust cover is ready fo launch itself into oblivion.

What is the complete system configuration? Driver compliment, amp power and channel compliment and crossover setup you are using?

[karl k]

The mains are bi-amped and the 10's run below 100-125hz????

You are not using the dual 18" sub in this system???

Sounds like one of the voice coils is delaminating from the cone or a dust cover is ready fo launch itself into oblivion.

What is the complete system configuration? Driver compliment, amp power and channel compliment and crossover setup you are using?

It was gettin kinda lonely around here!

You may be on to something with the delamination thing. Since I posted the original, I've been able to eliminate the amp, receiver, wire lead slap, and the box(cabinet) as the problem. Ive also discovered something I didn't count on and that's where your assessment comes into play. On the chance the sound was due to the VC, I started to check for VC alignment within the motor structure. Simply put, I just pushed in on the cone and observed any resistance that might indicate the VC rubbing on the motor. If I push on the center of the cone(w/o power applied) the woofer moves just fine. If I pushed on the edge of the cone(any given edge), you'ld expect the VC to eventually rub... right? Well it does BUT not in a consistant manner. Some edges, the VC makes immediate contact and some you have to push pretty hard to get the same contact. What does this indicate? It tells me that the VC is not in the motor structure in a uniform manner. Either off center, cocked(Uh-uhh-huh-huh) or both. Why does this matter? I believe that the movement of the cone is pretty linear(straight in and out) as long as the signal doesn't get to high. Once the signal increases past a certain point,(fortunately close to the rated power cap.) the cone and the VC begins to experience a lateral movement... small but just enough in conjunction with the VC being out of alignment to cause the VC to rub in the motor. This would acount for alot of what I hear and when I here it. It would be alot like if you pulled down the whip antenna on your truck and let it go. It would go back and forth but as it did, it would also begin to go around and around and the farther you pulled it back, the worse it would get. It's not so much the distance it would travel, but the level of stored energy right before it changes direction.

Here's how and when the sound occurs.

Cracking sound durring loud passages of mostly rock music
Not as loud as VC bottoming would be but still very instantaneous
Happens more often if the active x-over point is raised
Doesn't seem to be related to max cone travel
Seems to happen at beginning of bass note OR when cone changes direction rapidly
Not overdriving the speakers with power(but peak power being applied is close to the RMS rating of the drivers)
Am hearing it in all woofers on mains only(not the sub)

That last one is of particular interest. The fact that I hear it in all woofers would indicate that all the woofers have VC's that are off center when in fact that's not the case. But, since the woofers are in pairs(parallel) if one VC on each channel is rubbing,(which is the case) then the break in the electrical signal would translate to the other woofer on that channel. The question now, I believe, isn't how to fix it but whether I induced the prob or is it more likely that the speaker was just built that way.

BTW, it's good to hear from you again!

[Dual-500]

You probably are right Karl - I agree with your asessment.

Find a speaker recone shop - a small mom & pop shop that handles the pro's in your area - the musicians and sound contractor shops.

They can dissolve the glue around the voice coils and re-mount them with shims between the coil and the pole for you for a reasonable fee.

I've had some low mid 12's do that before. When driving high power in the low midrange frequency band, this is a common problem. The speakers literally begin to disintegrate.

good to chat with you bro, been a while.

I saw a post from Hertzie on the forum a few minutes ago.

Steve

[karl k]

You probably are right Karl - I agree with your asessment.

Find a speaker recone shop - a small mom & pop shop that handles the pro's in your area - the musicians and sound contractor shops.

They can dissolve the glue around the voice coils and re-mount them with shims between the coil and the pole for you for a reasonable fee.

I've had some low mid 12's do that before. When driving high power in the low midrange frequency band, this is a common problem. The speakers literally begin to disintegrate.

good to chat with you bro, been a while.

I saw a post from Hertzie on the forum a few minutes ago.

Steve

I'll look around and see if that's an option. The last place in town I knew of was Galaxy Audio. Been closed now for about 18yrs. Damn it!

I talked with Chris about it and was hoping you might have some experience in this matter. At $60 each, I'm not sure it would be worth it. I can get more from Parts Express and now that I know what to look for, screen what comes in without the hook up.

Ya, it looks like Hertzie's back! Maybe he'll grace us with that whit of his more often!

I gotts admit, I'm really starting to like this Numark amp. I prolly could have gotten something better, but I think this will do just fine as long as it is problem free. It also took alot of the load off the receiver. Hasn't shut down once since I bi-amped the mains. I'm pretty much ready to do the final cabinets and put on the finish. I'll shoot you some pics and details when I'm done.

[Dual-500]

$60.00 a piece is exactly my point. Shoving 200w to a $60.00 driver is hitting things pretty hard, especially in the low mid band for a 10".

Not ragging your drivers or choices here bro.

What I"m saying is that IF they are thrown together on the assembly line - maybe, maybe not - a good technician can glue them up real nice for you - make them better than OEM for maybe $30.00 a piece.

I say this without looking at your drivers - but I also say this having some years experience dealing with speaker repair shops.

Find a shop you can talk to someone about it and take them the drivers and let them have a look. You could even find someone on the web or in another area and ship them to have them "tweaked".

Something to think about.

[jneutron]

Check the litz to VC solder joint. I've had that fail intermittantly.

John

[kingdaddykeith]

A pair of CSX 10's for each channel(L/R), in an enclosure equalling 180L in volume, tuned to 30Hz via 5"id x 9"lg port, wired in parallel for a net imp. of 4ohms, driven by a Numark Dimension 3 amp in 2ch mode w/onboard active x-over set at about 100-125Hz. Amp is rated at 475wts rms/ch at 4ohms and is 2ohm stable. Amp has clip indicators and multi segment vu meters for monitoring.

That seems too large a enclosure for the drivers, with that port and that enclosure volume you shouldn’t need much power at all to reach x-max. I didn’t do any simulations with these exact drivers, but just from the hip 180L seems very large for these.

I think your way under-damped, try lowering the Q by overstuffing the enclosure and see if that helps. Also try stuffing the port.

[EFE Speakers]

Karl,
Try remounting your drivers 180 degrees from where they are now. Sometimes that will work rather than having to spend the money to have the motors re-aligned. If in deed the voice coils are not centered and you have the least space at the top, they can rub from the weight of the cone. Turning 180 degrees will help sometimes. Success!

Ed Frias
EFE Speakers