GR Drivers and active crossover

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Zitoun

GR Drivers and active crossover
« on: 5 Sep 2020, 03:19 pm »
Hello as I am waiting the border to reopen, I have been drafting my new system concept on a Servo Sub + NX -MTM basis, looking at evolving one day into a Super7 in the future.

I have 2 main questions for the community here

1- Can we have 4 Drivers on the Sub Amplifier (A370PEQ) to support both Left and Right Channel at the same time
2- Is it better to use a XLR spliter from the DAC to get to the Sub Amp or have the crossover to feed the sub amp. (current design would allow me to go to a 4 way crossover configuration)

3- Does the configuration below has any weak link?

See the concept below based on a 3 way crossover separation.




Peter J

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Re: GR Drivers and active crossover
« Reply #1 on: 5 Sep 2020, 03:45 pm »
1. Wouldn't that require a stereo amplifier? If memory serves me, the right/left signals are summed to a single output on the A370PEQ.

The rest, I dunno. Maybe Danny could help, but it seems unnecessarily complex. What's the design target?

nickd

Re: GR Drivers and active crossover
« Reply #2 on: 5 Sep 2020, 04:47 pm »
I suppose you could drive 4 of the 16FR with one A370 amp. Danny or Brian would need to chime to advise on if the difference in load changes the amp eq that is set for a pair of 16FR woofers. I think you will need to wire in series/parallel for the amp to see the same load.

The electronic crossover is a more difficult issue. I would advise using a Danny’s crossovers in the NX-MTM unless you have very advanced measuring equipment and lots of expierence measuring at different angles and adjusting via DSP with some pretty good software. Getting smooth frequency response and perfect phase with raw drivers and diss-similar amplifiers will most likely be impossible.

There are some things he can do with passive parts that are very difficult to attain similar response using DSP filters. Danny’s crossovers are some of the very best in the business at any price level. You will like the results keeping it simple. The passive crossover based speaker will not be the weak link in the chain.

Just my opinion, but I have tried DSP crossovers and used several of Danny’s passive filters. I had help with the DSP crossover from a retired JBL engineer. After seeing the amount of effort and exotic tools involved, I would not try it myself.

corndog71

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Re: GR Drivers and active crossover
« Reply #3 on: 6 Sep 2020, 03:54 pm »
The A370-PEQ can only drive 3 of the 16 Ohm woofers.  A fourth would drop the impedance too low.

Hobbsmeerkat

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Re: GR Drivers and active crossover
« Reply #4 on: 6 Sep 2020, 06:08 pm »
Actually, that that point you just need to run two series sets in parallel. Danny has mentioned in the past a single plate amp can drive 6 drivers, but not all in parallel.


HAL

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Re: GR Drivers and active crossover
« Reply #5 on: 6 Sep 2020, 11:48 pm »
The Rythmik Audio A370PEQ servo amps do not have XLR inputs, the A370-XLR3 has R-L XLR inputs if you want a mono sum of the channels since it is a mono servo amp.  Any of the A370 line servo amps are mono amps.  You would need an XLR to unbalanced converter to go from XLR to RCA output and not pickup noise.  You can try an XLR to RCA unbalanced cable, but depends on the balanced output implementation in the DSP crossover to see if any 60Hz ground loops occur.

For true stereo subs you need two A370 servo amps.  That would solve the low impedance of 4 drivers on one servo amp.  The version amp depends on the input style needed.

Make sure you mention that you want the Rythmik Audio open baffle sub servo amp version to get the correct amps.

Yes, you do need a test system and measurement knowledge to do speaker measurements to design correct digital crossovers for speakers.  I wrote a 21 page manual on how to do speaker measurements about 16 years ago for a system called the Mobile Measurement Kit (MMK) for doing speaker correction data collection for the Perpetual Technologies P-1A digital processor.   Fun stuff.

Good luck with your setup.

Jaytor

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Re: GR Drivers and active crossover
« Reply #6 on: 7 Sep 2020, 01:50 pm »
The amp needs to be close (within a few feet) of the drivers in order for the servo circuit to work effectively, so two amps are required to get any stereo separation.

Danny Richie

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Re: GR Drivers and active crossover
« Reply #7 on: 8 Sep 2020, 01:05 am »
Hello as I am waiting the border to reopen, I have been drafting my new system concept on a Servo Sub + NX -MTM basis, looking at evolving one day into a Super7 in the future.

I have 2 main questions for the community here

1- Can we have 4 Drivers on the Sub Amplifier (A370PEQ) to support both Left and Right Channel at the same time

Three drivers are the limit.

Quote
2- Is it better to use a XLR spliter from the DAC to get to the Sub Amp or have the crossover to feed the sub amp. (current design would allow me to go to a 4 way crossover configuration)

Typically you'll want to feed it through a pre-amp.

Quote
3- Does the configuration below has any weak link?

Oh yea, big time.

There are budget level passive filters and there are super high quality passive filters. The same is true for electronic crossovers.

If you are really good and designing them then a custom electronic crossover can be designed for those drivers. Doing so would be complex and pricey to use high quality parts and power supplies.

Off the shelf electron crossovers typically pass the signal through a group of op amps, have small and noisy A/C power supplies, and only allow control of crossover slopes and not control over a driver within its pass band.

So adding an average budget level electronic crossover to an NX-Otica MTM design is like building a race car and putting in a budget level underpower engine.

As designed the passive filters in the NX-Otica MTM are top level just like the drivers. Build it as is to get the best results.

Zitoun

Re: GR Drivers and active crossover
« Reply #8 on: 8 Sep 2020, 01:23 pm »
Thanks All, thanks Danny, lots of great feedback.

To summarize the network should be - source (toslink) - toslink switch (toslink) - DAC (xlr) - Preamp (xlr/rca) - servoSub (xlr) - amplifier (rca)

On the servo sub side, I will really like to decrease the number of devices, can we use the  H600XLR3 which is 600 watt RMS to drive the 4 drivers ?

And is there any downside?

Are they true stereo on the output for the drivers ?

SEE BELOW



Danny Richie

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Re: GR Drivers and active crossover
« Reply #9 on: 8 Sep 2020, 01:59 pm »
The HX600 is a little too much power for the application and could over drie the woofers in some cases.

And all of the amps are mono amps.

Tyson

Re: GR Drivers and active crossover
« Reply #10 on: 8 Sep 2020, 06:26 pm »
Also for the subs, the servo circuit works best if the sub amps are physically as close to the speakers as possible.  That means long RCA runs and very short speaker cables.  You can't do that with a single amp. 

WC

Re: GR Drivers and active crossover
« Reply #11 on: 8 Sep 2020, 06:56 pm »
With the Nx-MTM the servo subs are also running up higher to around 150 to 200 Hz than normal servo subs since they are part of the speaker. I think you would require two amps. One for the Left speaker servo sub and one for the Right speaker servo sub.

Zitoun

Re: GR Drivers and active crossover
« Reply #12 on: 10 Sep 2020, 04:07 am »
Ok, So that's interesting that there is a stereo input for a mono preamp., if they are mono then it means that we can't have stereo sound in the output except if we split left and right channel in 2 mono amps. Plus the driver cable length issue, that kills the idea of having only one,

Here is the new schema, let me know if you see any weak link, the one I identified so far is the old stereo Amp Cambridge SR10, but not sure if this is that important.





Peter J

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Re: GR Drivers and active crossover
« Reply #13 on: 10 Sep 2020, 02:31 pm »
When I Google the SR10, I come to a receiver. Presumably you'd be using the Cambridge amp section only, is that even possible? Bypassing built-in preamp isn't possible in some receivers.

 I think you've correctly identified the weak link in the proposed chain.

Zitoun

Re: GR Drivers and active crossover
« Reply #14 on: 10 Sep 2020, 03:45 pm »
Not Possible to Bypass, indeed,

Ok then I ll open a new thread on Amplifiers for this setup.

MarvinTheMartian

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Re: GR Drivers and active crossover
« Reply #15 on: 10 Sep 2020, 10:27 pm »
Zitoun:
You have already been given excellent feedback. K.I.S.S.
- build the two dual servo subs with two plate amps for any one of the following.
- build the passive version of NX-MTM, Super-Mini or Super-7 according to Danny’s  original plans.

My own suggestions, also  based on the  K.I.S.S. principle
- drop the optical splitter and buy an equal quality DAC/Integrated  or DAC/PRE + AMP  with three inputs, optical, hdmi and usb.

Sit back and enjoy.
Shawn

Zitoun

Re: GR Drivers and active crossover
« Reply #16 on: 11 Sep 2020, 01:09 am »
Damn, This is quiet  good catch,

I'll receive the new Burson end of month, I already have a small Topping E30 I can reserve for TV/Video Games, the PS4 is delivering PCM @ 48Khz, this will be more than enough to hear music and zombies in last of us II.

This should look like this


MarvinTheMartian

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Re: GR Drivers and active crossover
« Reply #17 on: 11 Sep 2020, 01:51 am »
Zitoun:
You missed the KISS point completely !
- ditch the Burnson a buy a buy an equal quality DAC/Integrated  or DAC/PRE + AMP  with appropriate inputs, optical, hdmi and usb
Basic  "Keep It Simple Stupid" principle. 

Shawn



 

Zitoun

Re: GR Drivers and active crossover
« Reply #18 on: 11 Sep 2020, 02:12 am »