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Author Topic: Using passive tops with powered subs  (Read 925 times)

Jose Peralta

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Using passive tops with powered subs
« on: May 28, 2023, 01:14:10 PM »

Hi, I am on the process in doing an upgrade on the subs. Currently have the CV horn loaded subs and thinking on going powered to a RCF 8006-AS or even the 9006, DAS UX 218A, or something equivalent. It would be only 2 boxes(one per side). My question is even though some active subes have some form of processing in them, can I leave the subs at default position and still run the driverack PA2 as the crossover and processing? I will be using an X18 as a mixer. The tops are JBL dual 15 and are passives. 
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Scott Bolt

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Re: Using passive tops with powered subs
« Reply #1 on: May 28, 2023, 01:47:18 PM »

Hi, I am on the process in doing an upgrade on the subs. Currently have the CV horn loaded subs and thinking on going powered to a RCF 8006-AS or even the 9006, DAS UX 218A, or something equivalent. It would be only 2 boxes(one per side). My question is even though some active subes have some form of processing in them, can I leave the subs at default position and still run the driverack PA2 as the crossover and processing? I will be using an X18 as a mixer. The tops are JBL dual 15 and are passives.
Yes.

The processing in powered speakers is quite small (sub msec).  To put it in perspective, sound travels 1ft / mSec.  This means that the processing time is likely miniscule compared to the difference in time from the placement of the subs to the tops to the persons ear.  It is certainly not as big a deal as the comb filtering effect of using more than one speaker.

If you are really interested, you can analyze the signal by using a metronome sound input and watching the output of a pair of microphones pointing directly at the tops and the subs.  You could put delay in to adjust using the DRPA.  My guess is that it is minimal.

The distance from the drums to the audience is typically 5-10 feet.  This gives you 5 to 10 msec of time mis-alignment from the acoustic sound to the amplified sound reaching the audiences ears.  This would be a much bigger factor to align IMO than the speaker processing.
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Jose Peralta

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Re: Using passive tops with powered subs
« Reply #2 on: May 28, 2023, 09:48:49 PM »

Yes.

The processing in powered speakers is quite small (sub msec).  To put it in perspective, sound travels 1ft / mSec.  This means that the processing time is likely miniscule compared to the difference in time from the placement of the subs to the tops to the persons ear.  It is certainly not as big a deal as the comb filtering effect of using more than one speaker.

If you are really interested, you can analyze the signal by using a metronome sound input and watching the output of a pair of microphones pointing directly at the tops and the subs.  You could put delay in to adjust using the DRPA.  My guess is that it is minimal.

The distance from the drums to the audience is typically 5-10 feet.  This gives you 5 to 10 msec of time mis-alignment from the acoustic sound to the amplified sound reaching the audiences ears.  This would be a much bigger factor to align IMO than the speaker processing.

Thanks for information. I am aware of the latency in DSP processing with speakers that have built in amplifiers. I guess going from a driverack to another DSP of the sub built in amp might add more latency.
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Steve-White

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Re: Using passive tops with powered subs
« Reply #3 on: May 28, 2023, 10:18:04 PM »

Thanks for information. I am aware of the latency in DSP processing with speakers that have built in amplifiers. I guess going from a driverack to another DSP of the sub built in amp might add more latency.

dbx specs the DriveRack PA2 at:  Latency: Input to output: 1.847 ms

Nothing to be concerned with, that's about 22".

Powered speakers, no idea on that topic.  You would want to know the specs to get everything set right - simple math will get you in the ballpark.
« Last Edit: May 28, 2023, 10:20:07 PM by Steve-White »
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Matt Vivlamore

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Re: Using passive tops with powered subs
« Reply #4 on: May 30, 2023, 01:22:01 PM »

I am the opposite... I have powered tops (RCF TTP4A) and passive subs (CD218 - B&C loaded) with Gruppen FP+ and Clair iO DSP.  We smaarted my set-up and found the 'delay' to be very minimal and not enough to worry.  I run the TT's through the Clair iO and run them on the L1 setting (full range/flat).

I started with a full SRX800 system and quickly found its faults (aka out grew it).  First, I replaced the mains with RCF TTP4A and then 1 TT's could easily out run 2x SRX828SP.  After buying the TT4s, I began saving/budgeting for 4x RCF SUB9006/TT36 subs and at ~$8k each it wasn't cost effective.  Then a local company was selling their subs and I couldn't pass up on the price (when I'm all said and done, I'll have invested less than $10k on 4x subs with proper power).

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Scott Holtzman

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Re: Using passive tops with powered subs
« Reply #5 on: May 30, 2023, 09:40:46 PM »

I am the opposite... I have powered tops (RCF TTP4A) and passive subs (CD218 - B&C loaded) with Gruppen FP+ and Clair iO DSP.  We smaarted my set-up and found the 'delay' to be very minimal and not enough to worry.  I run the TT's through the Clair iO and run them on the L1 setting (full range/flat).

I started with a full SRX800 system and quickly found its faults (aka out grew it).  First, I replaced the mains with RCF TTP4A and then 1 TT's could easily out run 2x SRX828SP.  After buying the TT4s, I began saving/budgeting for 4x RCF SUB9006/TT36 subs and at ~$8k each it wasn't cost effective.  Then a local company was selling their subs and I couldn't pass up on the price (when I'm all said and done, I'll have invested less than $10k on 4x subs with proper power).


If the local company was making money with those subs why would they sell them.  You didn't say what they are?  How do they compare against the TT's.  My guess is at some point you will end up with the TT's.



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Matt Vivlamore

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Re: Using passive tops with powered subs
« Reply #6 on: May 30, 2023, 10:52:39 PM »


If the local company was making money with those subs why would they sell them.  You didn't say what they are?  How do they compare against the TT's.  My guess is at some point you will end up with the TT's.

The subs I picked up where designed and built by Evan Kirkendall/Harford Sound and loaded with a pair of b&c 3000w cont. drivers (can't remember the model number).  He sold them because they picked up more d&b B22 subs and it makes it 'easier' to fill riders with a "full" d&b V or KSL system (he still owns a few for the budget/b-c stages/non-rider festivals).  They have a couple db more output than the B2's but a couple less db than the B22.

I've used these subs a plenty of times over the last ~6 years in various configurations and always enjoyed them.  The few 'common' rigs that I used was... the small 'ground stack' of 1x CD218, 1x Q-sub & 2-4x Q1's pre side.  And the typical SL100 system would be 4-6x V8's flown preside with 4x CD218s center clustered.  Subs were mainly powered with a PLM20k, but sometimes used the D12 or D80 as well.

One of the room I did for a few years in a row, Evan would provide the PA (CD218/Qsub/Q1, all powered with D12 amps) and then last year Evan told me to bring in PA and I bought in 4x SRX828SP.  I noticed a HUGE different in sound and immediately sold the SRX's and bought the CD218s off Evan.  Right now, I am driving a pair of the subs with the FP9000 (3000w @ 4ohms) and it's been enough for the shows that I've had.  I do have plans on getting a different amp and looking at a PLM20k (4400w @ 4ohms) or a pair of K10-DSP (4000w @ 4ohms).  Yes, I wanted to buy the RCFs, but couldn't justify the expense. 

Here is a little information: https://www.facebook.com/113681285314238/posts/pfbid0sBpznyJX7aVqiaVppqe6FbhVhC9dPQqPEsMVZ9Xn9qUXZZCFAZ7MwMETiUnJjpKMl/?mibextid=gkx3sN
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Jose Peralta

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Re: Using passive tops with powered subs
« Reply #7 on: June 03, 2023, 11:16:14 AM »

dbx specs the DriveRack PA2 at:  Latency: Input to output: 1.847 ms

Nothing to be concerned with, that's about 22".

Powered speakers, no idea on that topic.  You would want to know the specs to get everything set right - simple math will get you in the ballpark.

Steve thanks for the information. The subs is where I want to go active just for simplicity but I was concern with the latency between the driverack and the built in amp of the subs. I still want to keep the tops passive for right now so right now I can problably add some delay on the driverack to compensate the difference with the sub plus any more delay I need when I place the speakers. I have Smaart so I can see the outcome.
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Matt Modica

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Re: Using passive tops with powered subs
« Reply #8 on: June 04, 2023, 12:53:47 PM »

Steve thanks for the information. The subs is where I want to go active just for simplicity but I was concern with the latency between the driverack and the built in amp of the subs. I still want to keep the tops passive for right now so right now I can problably add some delay on the driverack to compensate the difference with the sub plus any more delay I need when I place the speakers. I have Smaart so I can see the outcome.

Another idea is to run a full range signal from your board and use the driverack's crossover. That way any latency introduced by the driverack is even, and you can adjust the delay on the hi/low outputs independently if needed for alignment.

Oh, and DBX just updated the PA2 app after not having done so in years.
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Jose Peralta

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Re: Using passive tops with powered subs
« Reply #9 on: June 08, 2023, 11:46:54 PM »

Another idea is to run a full range signal from your board and use the driverack's crossover. That way any latency introduced by the driverack is even, and you can adjust the delay on the hi/low outputs independently if needed for alignment.

Oh, and DBX just updated the PA2 app after not having done so in years.

Matt thanks for the response. That is how I currently have the signal run to the driverack. The pa setup is pretty much going to be the same at different location I will go to so alignment can be minimized unless speaker placement is different. 
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ProSoundWeb Community

Re: Using passive tops with powered subs
« Reply #9 on: June 08, 2023, 11:46:54 PM »


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