GR subs

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HAL

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Re: GR subs
« Reply #20 on: 1 Dec 2016, 10:49 pm »
The A370PEQ Delay/Phase control lets you adjust the time delay or phase at the crossover frequency for the sub.  That is what the 0mS to 18mS range means on the control means.  The high level inputs will take the integrated outputs.  Even though they are behind the speakers at those frequencies, but wavelengths are very long and phase will get you close. 

You can use PC or MAC with a program like Room EQ Wizard and a measuring mic for setup for best bass response running the sub with the main speakers. 

mirekti

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Re: GR subs
« Reply #21 on: 1 Dec 2016, 10:58 pm »
The A370PEQ Delay/Phase control lets you adjust the time delay at the crossover frequency for the sub.  That is what the 0mS to 18mS range means on the control means. 

HAL, I appreciate your effort, however, I don't think you understood well what my concern was (not sure if it is valid).

If the subwoofer is placed behind the main speakers, the sound coming from it would be delayed compared to the main speakers. By using the knob which delays the signal from 0ms to 16ms I will be able to put the sound in phase, but I will delay it even more.
My understanding is the mains and sub will end up being in phase, but the sound from the sub will be delayed by a cycle, two cycles, not sure.
That's why I posted the question whether this time difference is the sound arriving to the listener position between the mains and subwoofer will be noticeable or not (even though sounds of both sources are "in phase").
I hope this makes more sense now. I will repeat, I am not claiming anything just trying to comperhand whether it is worth trying to integrate my mains with the subs or not.

Thanks!!!

HAL

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Re: GR subs
« Reply #22 on: 1 Dec 2016, 11:06 pm »
Yes, I understand the sound of the subs is delayed being behind the mains.  That is very typical.  The phase control will do a lot to align the two speakers.  It is not perfect, but much better than no adjustment.  The wavelengths you are using at the crossover frequency are very long, so phase adjustments get close.

You are correct that the best is adding time delay to the mains to match the subs, but that would not work with an integrated that does not have a user input connection between the preamp and power amp sections and splitting the signal with time delay to the mains, and feed the servo subs line level inputs.




Danny Richie

Re: GR subs
« Reply #23 on: 2 Dec 2016, 01:47 am »
Keep in mind that your speakers crossover also causes a delay. So they may not be near as in front of the woofers as you think. You may actually have to add delay. And the length of the wavelength of 40Hz is about 28 feet long. So a three foot time delay at those frequencies are not much of a phase rotation.

mirekti

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Re: GR subs
« Reply #24 on: 2 Dec 2016, 09:50 pm »
Thanks for the clarification!!
 
As P3ESR has -3db@75Hz, and I can only send line out to the subwoofer, would it be better if I purchased something like this http://www.parts-express.com/harrison-labs-fmod-inline-crossover-pair-70-hz-low-pass-rca--266-252 , plug them between the line out and line in and set the amp to AVR/12?
My line outs are one L and one R, do I need to use some splitter in case of two subs or I simply connect line out L to L of 1st subwoofer and line out R to L of 2nd subwoofer?
Also, P3ESR has 12db roll off and sub will have 24db will this be hard to integrate?

THROWBACK

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Re: GR subs
« Reply #25 on: 2 Dec 2016, 11:55 pm »
This discussion got me to thinking.
Let's say the crossover point between mains and subs is 80Hz. What if you could dial in an oscillator with an 80 Hz sine wave and send the tone to both main and sub at the same time? With microphones set up in front of each and outputs routed to an oscilloscope, wouldn't it be possible to sync the two signals into looking like a single sine wave by adjusting the A370PEQ (or other) phase control? And wouldn't this be more accurate than trying to set the system up by ear?

My friend, Greg chimed in: Also you could eliminate possibility of microphone differences by using only a single microphone. For that case you could store and display the first waveform (as reference), after which you could watch the 2nd waveform (real-time, superimposed on the screen). You would then adjust phase control for zero phase between the real-time waveform vs. stored reference waveform.

mirekti

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Re: GR subs
« Reply #26 on: 4 Dec 2016, 03:07 pm »
There is one other thing I cannot find the information for, and that's how sensitive the volume knob is, so anyone's comment is welcome.
P3ESR's sensitivity/m is as follows:
1w 83dB
2w 86dB
4w 89db
8w 92dB
16w 95 dB
32w 98 dB

I only found the info GR driver is 88dB. If I understand this well, then I would need to turn the volume knob on the amp to use a bit less then 4w to level the volume up with main soeakers, and in case of two subs even less.
Will this be hard to do given the amps power of 370W?
Actually, how does the vokume knob work is it linear?

Thanks!!

THROWBACK

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Re: GR subs
« Reply #27 on: 4 Dec 2016, 03:45 pm »
And then I thought, why would you need an oscilloscope? Why not just reverse the leads on the sub and listen for a null by adjusting the phase control knob?
I probably should try this for myself before spouting off , but I'd like to hear what you guys think.

To recap:
1. Place the mains and subs where you want to
2. Reverse the leads on one of the the subs so that it is 180 degrees out of phase with its main
3. Send a tone at the crossover point to both the main and the sub (say, 80 Hz)
4. Use the phase control to null out the sound.
5. If you run out of travel on the phase control knob, move the sub and try again.
6. Do the same for the other main/sub combo

Should this work? If not; why not?

Danny Richie

Re: GR subs
« Reply #28 on: 4 Dec 2016, 11:09 pm »
Thanks for the clarification!!
 
As P3ESR has -3db@75Hz, and I can only send line out to the subwoofer, would it be better if I purchased something like this http://www.parts-express.com/harrison-labs-fmod-inline-crossover-pair-70-hz-low-pass-rca--266-252 , plug them between the line out and line in and set the amp to AVR/12?
My line outs are one L and one R, do I need to use some splitter in case of two subs or I simply connect line out L to L of 1st subwoofer and line out R to L of 2nd subwoofer?
Also, P3ESR has 12db roll off and sub will have 24db will this be hard to integrate?

Are you talking about using the line out RCA outputs on the servo amps?

Also, the FMod values can be a bit misleading. They advertise a crossover value, but the actual crossover value varies a LOT depending on the input impedance of your amp. So it may or may not work as advertised. Also, the quality level of those are mediocre at best.

And you will never need to add something like that to the servo amp. The amp already has crossover control functions right there on the amp. 

Danny Richie

Re: GR subs
« Reply #29 on: 4 Dec 2016, 11:11 pm »
This discussion got me to thinking.
Let's say the crossover point between mains and subs is 80Hz. What if you could dial in an oscillator with an 80 Hz sine wave and send the tone to both main and sub at the same time? With microphones set up in front of each and outputs routed to an oscilloscope, wouldn't it be possible to sync the two signals into looking like a single sine wave by adjusting the A370PEQ (or other) phase control? And wouldn't this be more accurate than trying to set the system up by ear?

My friend, Greg chimed in: Also you could eliminate possibility of microphone differences by using only a single microphone. For that case you could store and display the first waveform (as reference), after which you could watch the 2nd waveform (real-time, superimposed on the screen). You would then adjust phase control for zero phase between the real-time waveform vs. stored reference waveform.


I set them up using measurements from our Clio system. It just takes a few minutes to dial the subs and main speakers in so that they are in phase.

But once you know what to listen for you can also dial them in by ear pretty quick too.

Danny Richie

Re: GR subs
« Reply #30 on: 4 Dec 2016, 11:15 pm »
There is one other thing I cannot find the information for, and that's how sensitive the volume knob is, so anyone's comment is welcome.
P3ESR's sensitivity/m is as follows:
1w 83dB
2w 86dB
4w 89db
8w 92dB
16w 95 dB
32w 98 dB

I only found the info GR driver is 88dB. If I understand this well, then I would need to turn the volume knob on the amp to use a bit less then 4w to level the volume up with main soeakers, and in case of two subs even less.
Will this be hard to do given the amps power of 370W?
Actually, how does the vokume knob work is it linear?

Thanks!!

You are making this way more difficult than it is. This is actually very easy.

Play your main speakers to a constant level then turn up the volume knob on the servo amp until the levels match. You don't even need a meter. I use a reference song that gets me there in about 15 seconds.

And driver sensitivity is irrelevant.

Danny Richie

Re: GR subs
« Reply #31 on: 4 Dec 2016, 11:17 pm »
And then I thought, why would you need an oscilloscope? Why not just reverse the leads on the sub and listen for a null by adjusting the phase control knob?
I probably should try this for myself before spouting off , but I'd like to hear what you guys think.

To recap:
1. Place the mains and subs where you want to
2. Reverse the leads on one of the the subs so that it is 180 degrees out of phase with its main
3. Send a tone at the crossover point to both the main and the sub (say, 80 Hz)
4. Use the phase control to null out the sound.
5. If you run out of travel on the phase control knob, move the sub and try again.
6. Do the same for the other main/sub combo

Should this work? If not; why not?

It is easier than that. You don't even have to reverse the wiring on the subs. You can just turn the dial to do the same thing. You can create a complete null or perfect alignment just by turning the knob.

mirekti

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Re: GR subs
« Reply #32 on: 4 Dec 2016, 11:33 pm »
Are you talking about using the line out RCA outputs on the servo amps?

Also, the FMod values can be a bit misleading. They advertise a crossover value, but the actual crossover value varies a LOT depending on the input impedance of your amp. So it may or may not work as advertised. Also, the quality level of those are mediocre at best.

And you will never need to add something like that to the servo amp. The amp already has crossover control functions right there on the amp.

Thank you very much for spending your time in answering my questions, I truly appreciate it.

My amplifier has L and R line level outputs so L would be used to be connected to the left subwoofer and R would be used to connect it to the right subwoofer.
I just wondered where exactly should these be connected to the subwoofer inputs, L to L of left subwoofer's RCA input and R to L of right subwoofer's RCA input?

In regards to the crossover, I am just worried not to mess up the clarity of Harbeth. P3ESR are specified as -3db @75Hz and they roll off at 12db/octave. On the other hand subwoofer crossover switch can be set to 80Hz (I assume -3db), but with the slope of 24db/octave. I am worried there will be too much overlap between the two and I would need to use the PEQ to level it up (in that case I would not be able to use it at some other frequency which I would probably need due to the room modes). Hence, my idea of using FMods. Given your comments, I understand FMods wouldn't be a wise choice.

Ideally, I would need to have an amp which also had an option of 80Hz HPF which would relieve the mains of low freq load, but unfortunately I don't have such an option.

Danny Richie

Re: GR subs
« Reply #33 on: 4 Dec 2016, 11:48 pm »
Thank you very much for spending your time in answering my questions, I truly appreciate it.

My amplifier has L and R line level outputs so L would be used to be connected to the left subwoofer and R would be used to connect it to the right subwoofer.
I just wondered where exactly should these be connected to the subwoofer inputs, L to L of left subwoofer's RCA input and R to L of right subwoofer's RCA input?

You can use either the left of right input on either amp. It won't matter.

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In regards to the crossover, I am just worried not to mess up the clarity of Harbeth.

The clarity of the Harbeth? Aren't these the speakers with lightly built un-braced boxes.

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P3ESR are specified as -3db @75Hz and they roll off at 12db/octave. On the other hand subwoofer crossover switch can be set to 80Hz (I assume -3db), but with the slope of 24db/octave. I am worried there will be too much overlap between the two and I would need to use the PEQ to level it up

The controls on the plate amp will allow you to do anything you want with the response of the servo woofer. Just leave the control in the middle EXT/12 position and you simply have 12db per octave slopes controlled infinitely but the crossover control knob. You then can add an additional 12db per octave slope at 80Hz or 50Hz with the flick of a switch. 
 
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(in that case I would not be able to use it at some other frequency which I would probably need due to the room modes). Hence, my idea of using FMods. Given your comments, I understand FMods wouldn't be a wise choice.

You won't need the PEQ of blending the subs to your main speakers.

And yes, never add an FMod inline with the plate amp.

Quote
Ideally, I would need to have an amp which also had an option of 80Hz HPF which would relieve the mains of low freq load, but unfortunately I don't have such an option.

That's easy. Just use a high quality capacitor like a Sonicap Platinum as a high pass filter for your amp.

mirekti

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Re: GR subs
« Reply #34 on: 5 Dec 2016, 12:18 am »
Harbeth and clarity :) ...well, what I thought was the change in sound due to the fact both speakers would play same frequencies. Anyhow, I read somewhere AVR was used with the AMP which has bass management and totally ignored the crossover knob.  :duh:  I guess I am back on the track.
So if one sets the switch to AVR the crossover knob is what determines the line in lowpass frequency, but if one switches to 50Hz or 80Hz on the line in lowpass than the crossover knob becomes irrelevant?

Regarding the high pass filter, the problem is it is an integrated amp. The only way would be to put something before the speakers, but I am not sure if this is wise as I would actually add something to the crossover.

Thanks a lot. I don't think there any other reason not to get these subs.  :thumb:

Danny Richie

Re: GR subs
« Reply #35 on: 5 Dec 2016, 01:16 am »
Harbeth and clarity :) ...well,

You mean this speaker?



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what I thought was the change in sound due to the fact both speakers would play same frequencies.

You cross them over to one another where they are each 6db down. That will make your response flat.

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Anyhow, I read somewhere AVR was used with the AMP which has bass management and totally ignored the crossover knob.  :duh:  I guess I am back on the track.

Some of those receivers will send a 12db per octave sloped output to the sub outs. So using the center position on that switch adds just a 12db per octave slope controlled by the crossover control knob. So you get a 24db per octave slope depending on where you set the control.

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So if one sets the switch to AVR the crossover knob is what determines the line in lowpass frequency, but if one switches to 50Hz or 80Hz on the line in lowpass than the crossover knob becomes irrelevant?

No, the crossover knob is always active and is infinitely adjustable with a 12db per octave slope.

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Regarding the high pass filter, the problem is it is an integrated amp. The only way would be to put something before the speakers, but I am not sure if this is wise as I would actually add something to the crossover.

In that case the only way to filter the lows off of your speakers is to add a coupling cap to the input on the amplifier internally. 

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Thanks a lot. I don't think there any other reason not to get these subs.  :thumb:

You'll love the subs.

I can also help you upgrade those speakers. If you like the speakers and want to keep them then we can upgrade the crossover parts (the stock ones are really poor), binding posts, wire, and line the cabinets with No Rez. Clarity can be increased significantly on that model and across the board. It will improve the bass response and imaging as well.

mirekti

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Re: GR subs
« Reply #36 on: 5 Dec 2016, 02:20 am »
Thank you for all the details. I think the speakers are intentionally made "without" bracing. I am not sure I would like to change this.
I guess the crossover could be updated, there's always room for make crossover better, but for now the only thing I am willing to invest in is the lower two octaves from where the speakers roll off. I do appreciate your offer, though.   

Danny Richie

Re: GR subs
« Reply #37 on: 5 Dec 2016, 02:58 am »
Thank you for all the details. I think the speakers are intentionally made "without" bracing. I am not sure I would like to change this.
I guess the crossover could be updated, there's always room for make crossover better, but for now the only thing I am willing to invest in is the lower two octaves from where the speakers roll off. I do appreciate your offer, though.

Yeah those speakers are known for cabinet resonances in several ranges. Some feel like the resonances add a pleasing effect. But in reality it is noise that is not part of the input signal. And removing it can be quite an improvement. A sheet of No Rez will do wonders for them.

Subs, upgrades of any kind, etc. I'll help you with any of that whenever you're ready.

mirekti

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Re: GR subs
« Reply #38 on: 5 Dec 2016, 03:13 am »
Subs, upgrades of any kind, etc. I'll help you with any of that whenever you're ready.

Thank you very much, I'll certainly keep this in my mind.
Cheers!!!