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Author Topic: Sound reinforcementCan I run signal directly from amp to high frequency drivers?  (Read 7694 times)

stuartwgibson

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They really are 125w.  But you can see with a QSC 3400 running the highs, how I could easily overdrive these.  Still hoping to add 2 more, which would definitely solve the problem. 
Disconnected one HFD from the right and added it in parallell on the left.  So then with two identical HFDs on the left (one bi-amped through the cabinet crossover and one essentially running directly off the amp), the direct connected one was noticeablly louder.  Still waiting to hear from B-52 about the discrepency between their website specs and the specs on the comp3300 itself (16 ohms vs. 8 ohms)

Curses, fooled by the phony marketing specs again!
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Mark McFarlane

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Simply adding more HF drivers will make it louder-but it WILL ALSO make it sound WORSE.

Your best bet is to use FEWER-BETTER QUALITY HF drivers.  This way you can get louder and sound better.  Of course it will cost more.

Adding more subs is one thing-adding more highs is a totally different matter and MUCH hrader (to get them to sound good).  It is real easy electrically-but ACOUSTICALLY is where the challenge is.  It is one of the hardest things to do in audio-at least to do RIGHT.

Stuart, please take heed to this advice before you get carried away on technically how to do something that isn't a good idea in the first place.
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Mark McFarlane
ARKOSERECORDS
Turn down what's too loud.

Ivan Beaver

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They really are 125w. 
Once again- is that 125 continuous watts- or 125 program watts or 125 peak watts or something else?

How do you know?  So you have any specs or model numbers?  What is the voice coils size? etc.

All "watts" are not created equal.  There are real watts-marketing watts-power compression watts and so forth.

Just sayin' ------------------------------------------------------
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

stuartwgibson

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Appreciate all the feedback.  I can see that my choice is between running these straight out of my board cross-over/amp or building new cabs with a dedicated passive crossover (almost certainly the preferred choice, since it would add a good measure of protection).
I just have to make sure about the whole 16 ohms / 8 ohms thing. 
Can anyone think why the HFD itself would be marked 8 ohms on the back, while the b-52 specs call it a 16 ohms driver? 
FWIW, the selenium diapraghm inside the driver is 16 ohms.



Once again- is that 125 continuous watts- or 125 program watts or 125 peak watts or something else?

How do you know?  So you have any specs or model numbers?  What is the voice coils size? etc.

All "watts" are not created equal.  There are real watts-marketing watts-power compression watts and so forth.

Just sayin' ------------------------------------------------------
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Ivan Beaver

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Appreciate all the feedback.  I can see that my choice is between running these straight out of my board cross-over/amp or building new cabs with a dedicated passive crossover (almost certainly the preferred choice, since it would add a good measure of protection).
I just have to make sure about the whole 16 ohms / 8 ohms thing. 
Can anyone think why the HFD itself would be marked 8 ohms on the back, while the b-52 specs call it a 16 ohms driver? 
FWIW, the selenium diapraghm inside the driver is 16 ohms.
Probably because the load presented to the amp by the driver crossover COMBINATION is actually 8 ohms-even though the driver may be 16 ohms.

This is not uncommon.

Of course without an actual measurement (impedance- NOT resistance) there is no way to really say exactly what it is.

At least we have a manufacturer now-how about a model number?

COMPLETE INFORMATION REALLY HELPS!!!!!!!!!!!!  Instead of making people guess what you have--------------

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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

David Morison

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At least we have a manufacturer now-how about a model number?

COMPLETE INFORMATION REALLY HELPS!!!!!!!!!!!!  Instead of making people guess what you have--------------

To be fair, he did give that in both reply #5 and reply #20.

However, the manufacturer's page gives no more useful info than we have already (ie nominal impedance without a Z curve and only the single, undefined wattage number).
Regards,
David.
« Last Edit: July 11, 2013, 08:10:15 am by David Morison »
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Brad Weber

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They really are 125w.  But you can see with a QSC 3400 running the highs, how I could easily overdrive these.  Still hoping to add 2 more, which would definitely solve the problem. 
Disconnected one HFD from the right and added it in parallell on the left.  So then with two identical HFDs on the left (one bi-amped through the cabinet crossover and one essentially running directly off the amp), the direct connected one was noticeablly louder.  Still waiting to hear from B-52 about the discrepency between their website specs and the specs on the comp3300 itself (16 ohms vs. 8 ohms)
Can you clarify what you did and how you plan to wire these?  You need a crossover in there somewhere, either passive after the amp or active before it.  So are you saying you compared a horn and driver driven by an active crossover and then an amp with an identical horn and driver driven by the same amp but with no crossover before the amp and through the passive crossover of the speaker after the amp?  Or did the one go through an external crossover and the other through both that external active crossover and the internal passive crossover?  Or was one essentially run full range and the other through the internal passive crossover?
 
What you observed might be exoplained by the fact that chances are good that the passive crossover in the amp intentionally pads down the HF as typically the HF driver and horn are capable of greater output than the LF driver.  However, the fact that you say you are blowing HF drivers trying to keep up with the LF indicates that either that is not the case here or there may be something wrong in your setup.
 
Unfortunately, B-52 does not seem to offer the information needed to tell much of anything about the speakers or the components.  For example, the speaker info says it can be run bi-amped but the only data provided is for the full range mode.  The power handling ratings do not say what they represent or how they were determined, based on the Peak SPL and Sensitivity claimed the speaker rating appears to be a Program power rating while the driver ratings are claimed to be "R.M.S.".  The frequency responses are specified with no limits and no additional data offered.  And there is apparently no manual for the speaker or drivers.  Basically, B-52 does not provide the information necessary to make any informed responses or decisions regarding bi-amping your speakers.
 
But I think we may be getting away from the main point and that is exactly what you believe you are going to accomplish from all of this effort?  What change do you think a second HF driver and horn per side will cause?  You are not going to get the two HF drivers close enough for coupling over any of their bandwidth so the best possible result is +3dB overall, but probably with some negative affects on the response.  Is that really worth all of this?  Why not just keep it simple and either operate the sysyetm full range within its limits or if you absolutely need more output, get some better speakers to start with?
 
By the way, B-52 does say the crossover on the PA15x is 1.4kHz rather than 1.6kHz, but they don't provide any other information such as the filter types or slopes used.
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stuartwgibson

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Thanks for the detailed response..:-)  Yes, while b-52's high-end speakers (PA15x and the like) are nice pieces of equipment with great sound....... B-52's support and documentation are definitely lacking.  I'm using this system in an outdoor venue with about 1500-2000 watts output.  So I do need to reinforce the highs a little.  I think I'm going to replace my Yamaha S115vs (which are inferior and muddy) with b-52 PA-215s.  These have the same COMP 3300 HFDs we've been discussing, and will accomplish my goals without all the hassle.

Can you clarify what you did and how you plan to wire these?  You need a crossover in there somewhere, either passive after the amp or active before it.  So are you saying you compared a horn and driver driven by an active crossover and then an amp with an identical horn and driver driven by the same amp but with no crossover before the amp and through the passive crossover of the speaker after the amp?  Or did the one go through an external crossover and the other through both that external active crossover and the internal passive crossover?  Or was one essentially run full range and the other through the internal passive crossover?
 
What you observed might be exoplained by the fact that chances are good that the passive crossover in the amp intentionally pads down the HF as typically the HF driver and horn are capable of greater output than the LF driver.  However, the fact that you say you are blowing HF drivers trying to keep up with the LF indicates that either that is not the case here or there may be something wrong in your setup.
 
Unfortunately, B-52 does not seem to offer the information needed to tell much of anything about the speakers or the components.  For example, the speaker info says it can be run bi-amped but the only data provided is for the full range mode.  The power handling ratings do not say what they represent or how they were determined, based on the Peak SPL and Sensitivity claimed the speaker rating appears to be a Program power rating while the driver ratings are claimed to be "R.M.S.".  The frequency responses are specified with no limits and no additional data offered.  And there is apparently no manual for the speaker or drivers.  Basically, B-52 does not provide the information necessary to make any informed responses or decisions regarding bi-amping your speakers.
 
But I think we may be getting away from the main point and that is exactly what you believe you are going to accomplish from all of this effort?  What change do you think a second HF driver and horn per side will cause?  You are not going to get the two HF drivers close enough for coupling over any of their bandwidth so the best possible result is +3dB overall, but probably with some negative affects on the response.  Is that really worth all of this?  Why not just keep it simple and either operate the sysyetm full range within its limits or if you absolutely need more output, get some better speakers to start with?
 
By the way, B-52 does say the crossover on the PA15x is 1.4kHz rather than 1.6kHz, but they don't provide any other information such as the filter types or slopes used.
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