Greetings!
I have a pair of 3 way hybrid horn speakers which I put together myself.
It consists of a jbl 2402h for the highs, jbl2446h on jbl2380 horns for the mids and an eminence alpha 15 in a sealed enclosure for the lows.
Due to the difference in the efficiency of the drivers, I have padded the mids and highs down with an individual fixed l-pad attenuating 15db. My crossover is a 2nd order crossover with the crossover points being 800hz and 5khz.
My problem here is as my title states, unbalanced vocals. Even on mono signals, I have observed the vocals to seem to be louder on the left.
I have eliminated the following components in my system : ( pre and power amps ,audio source , crossovers and my ears.) as the cause of the phenomenon.
I am however suspecting phase issuees. As I am unsure if the diaphraghms are installed in correct phase. (How do I check for this?)
Another thing to note would be that the dcr of my drivers are all correct according to their spec sheet.
One other question I have would the 'resolution' of this speaker system be low? As I have listened to Chris Jones' "Roadhouses and automobiles" and I could barely hear the crickets.
Thank you in advance!
I have a pair of 3 way hybrid horn speakers which I put together myself.
It consists of a jbl 2402h for the highs, jbl2446h on jbl2380 horns for the mids and an eminence alpha 15 in a sealed enclosure for the lows.
Due to the difference in the efficiency of the drivers, I have padded the mids and highs down with an individual fixed l-pad attenuating 15db. My crossover is a 2nd order crossover with the crossover points being 800hz and 5khz.
My problem here is as my title states, unbalanced vocals. Even on mono signals, I have observed the vocals to seem to be louder on the left.
I have eliminated the following components in my system : ( pre and power amps ,audio source , crossovers and my ears.) as the cause of the phenomenon.
I am however suspecting phase issuees. As I am unsure if the diaphraghms are installed in correct phase. (How do I check for this?)
Another thing to note would be that the dcr of my drivers are all correct according to their spec sheet.
One other question I have would the 'resolution' of this speaker system be low? As I have listened to Chris Jones' "Roadhouses and automobiles" and I could barely hear the crickets.
Thank you in advance!
Hello Inductor !
Thank you for replying!
I have tried changing the phase this way and other on my mids as well as the other drivers in the system. However the condition still persists.
the crossover is unlikely to be the fault as I have tried swapping the speakers connected to the crossovers .
Could the diaphragm be faulty despite having an ideal dcr?
Thank you for replying!
I have tried changing the phase this way and other on my mids as well as the other drivers in the system. However the condition still persists.
the crossover is unlikely to be the fault as I have tried swapping the speakers connected to the crossovers .
Could the diaphragm be faulty despite having an ideal dcr?
A voice coil could be frozen (warped, uncentered, or othewise stuck in the gap), would make it not play while still having DCR. Try swapping HF and/or MF drivers between sides to see if the weak side follows one of them.
As far as "resolution", it is more likely to be a response shape problem. Using generic crossovers with drivers (particularly with horns) is almost sure to never be very flat. The crossover should be designed with the drivers and all their related curves and delays, otherwise there are likely to be cancellations and other bad response effects.
As far as "resolution", it is more likely to be a response shape problem. Using generic crossovers with drivers (particularly with horns) is almost sure to never be very flat. The crossover should be designed with the drivers and all their related curves and delays, otherwise there are likely to be cancellations and other bad response effects.
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Hello Quartz
If you're not using a Stepped Attenuator in your preamp, the problem can be in your volume control. The normal Stereo Log pots do not have very good tracking on both channels. It can vary by as much as 6dB.
You'll need to have some kind of measurement equipment like OmniMic, to plot the frequency response. The highs could be rolling off. It could also be our hearing. As we age, we lose the high frequencies. As it is, our ears are not linear ( see Munson & Fletcher )
Regards
Mike
Hello bwaslo!
Thanks for your reply!
I have indeed swapped the sides and the weak side follows. Thus I have concluded that it is indeed a problem with the 2446 on the right. Could there be any potential problems with such a driver besides a damaged diaphragm? E.G weakened magnets or shifted pole-piece and such? Although I strongly doubt either being my issue due to the driver being handled with much love and care all this while.
Regarding the 'resolution', I guess I will have to get myself an active crossover.
Thanks for your reply!
I have indeed swapped the sides and the weak side follows. Thus I have concluded that it is indeed a problem with the 2446 on the right. Could there be any potential problems with such a driver besides a damaged diaphragm? E.G weakened magnets or shifted pole-piece and such? Although I strongly doubt either being my issue due to the driver being handled with much love and care all this while.
Regarding the 'resolution', I guess I will have to get myself an active crossover.
Hello Michael Chua!
Thanks for your reply!
Yes I am indeed using a stepped attenuator in my main preamp and have tried with other preamps and amps.
Indeed I do have to measure my speakers. Have been wanting to do so since I built them around a year ago however I never got around to purchasing the equipment required.
Thanks for your reply!
Yes I am indeed using a stepped attenuator in my main preamp and have tried with other preamps and amps.
Indeed I do have to measure my speakers. Have been wanting to do so since I built them around a year ago however I never got around to purchasing the equipment required.
That would make quite a difference.
JBL used felt back in the "good old days" 50 year old felt generally is OK, foams vary widely.
Replace the foam, remove the diaphragms, clean the gaps, re-install and align the diaphragms and you may find the differences are reduced.
The alignment posts are a guideline, proper alignment using sine wave tones and shifting the voice coil in the gap is still often needed to eliminate voice coil dragging, which shows up as a "buzzing sound" when sweeping sine waves from around 200-500 Hz. You only need a fraction of a watt for testing, adjust the sine wave for a comfortable level at around 1200 Hz and sweep down and up.
Also check for any sharp edges on the horns, they don't always come out of the mold cleanly.
At any rate, all diaphragms are not created equal, if you swap diaphragms and the problem persists in the opposite driver you know it is diaphragm rather than a driver (magnetic) difference.
Also, when cleaning the gap, use some card stock to make sure the gap is consistent, the pole piece or keeper can shift if it was ever dropped or slammed around.
Art
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Hello jjrenman!
I have found the great unbalance to be slightly due to room acoustics however the difference was totally eliminated when I changed the entire driver with the spare I left at my mentor's shop. With the spare the leis still louder despite of which of the two properly functioning drivers I am using for the left side.
I have found the great unbalance to be slightly due to room acoustics however the difference was totally eliminated when I changed the entire driver with the spare I left at my mentor's shop. With the spare the leis still louder despite of which of the two properly functioning drivers I am using for the left side.
Hello weltersys!
I have decided to remove all of the old foam on both my properly functioning drivers for the time being until I can get a suitable replacement (would felt be better?). Strangely swapping the diaphragms around did not alleivate the problem thus I changed the weak driver out for a spare. Looking at the gap of the weak driver I could find no problems . The gap was uniform through out , the phase plug and the gap were clean. The driver was technically in a 'minty' condition I really could'nt find a fault that should cause it to sound weak.
Unlike my altec 802 8g , the 2446 does not have aligning pins rather they have a depression in which the outer ring of the diaphragm sits in snugly. Making it impossible for any adjustment of the diaphragm.
I have decided to remove all of the old foam on both my properly functioning drivers for the time being until I can get a suitable replacement (would felt be better?). Strangely swapping the diaphragms around did not alleivate the problem thus I changed the weak driver out for a spare. Looking at the gap of the weak driver I could find no problems . The gap was uniform through out , the phase plug and the gap were clean. The driver was technically in a 'minty' condition I really could'nt find a fault that should cause it to sound weak.
Unlike my altec 802 8g , the 2446 does not have aligning pins rather they have a depression in which the outer ring of the diaphragm sits in snugly. Making it impossible for any adjustment of the diaphragm.
Quartz,
Agree that checking the drivers are matched is important. Do you have any way to measure the drivers?
Personally I would be measuring, comparing, measuring again, comparing each pair of drivers just for level output to see how well matched they are. Make sure each pair of drivers are in the same condition - either a pair of new or a pair of old, but one new one old will never be a good idea.
If the output is slightly off between drivers you can accomodate that in the xo's.
equally, did you measure and check all the components you put into your crossover?
Many tollerances for xo components can be low, you may be unlucky in just having really poorly matched xo's. Personally I'd pull them apart and measure EVERY component to make sure they're performing as they should. You can measure the effective resistance of inductors/caps in the same way as you'd measure impedance curves with arta on a computer (very cheap and relatively easy, if time consuming) - gives you a chance to calculate the actual % variation)
I understand you've already tried swapping the speakers around in the room and switching driver polarity?
Agree that checking the drivers are matched is important. Do you have any way to measure the drivers?
Personally I would be measuring, comparing, measuring again, comparing each pair of drivers just for level output to see how well matched they are. Make sure each pair of drivers are in the same condition - either a pair of new or a pair of old, but one new one old will never be a good idea.
If the output is slightly off between drivers you can accomodate that in the xo's.
equally, did you measure and check all the components you put into your crossover?
Many tollerances for xo components can be low, you may be unlucky in just having really poorly matched xo's. Personally I'd pull them apart and measure EVERY component to make sure they're performing as they should. You can measure the effective resistance of inductors/caps in the same way as you'd measure impedance curves with arta on a computer (very cheap and relatively easy, if time consuming) - gives you a chance to calculate the actual % variation)
I understand you've already tried swapping the speakers around in the room and switching driver polarity?
Hello nanno!
The drivers were bought together at the same time. At risk of sounding like a über dummy, I have to admit
that the angle of the right speaker was off by around 5degrees which after rectification, have brought the balance back. (Are these horns so directional?)
Nonetheless I ought to measure to match my drivers and my crossover components when I get the time.
Thank you!
The drivers were bought together at the same time. At risk of sounding like a über dummy, I have to admit
that the angle of the right speaker was off by around 5degrees which after rectification, have brought the balance back. (Are these horns so directional?)
Nonetheless I ought to measure to match my drivers and my crossover components when I get the time.
Thank you!
Room acoustics and speaker placement have oft led me to believe I have issues with my system only to find a few degrees of rotation to a speaker will solve the issue. That being said, without a symmetrical room, you will likely perceive some type of imbalance or imaging issue. I had to find the best orientation and live with it, while making minor adjustments.
Felt shoe liners could be used, or the jute felt backing used beneath carpeting.
Never thought of wool shoe felt, now I can reappropriate my Mukluc's.
Never found a use for them in SUNNY HOT FLORIDA
Quartz, the felt under automotive carpet would also work. Junk yards should have tons, would cost next to nothing
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