Which amp to use with SW-8-16FR OB driver? & 200 Hz?

0 Members and 1 Guest are viewing this topic. Read 3539 times.

milosz

I am looking to build something using an electrostatic panel said to best used crossed over at 12 dB/octave at 200 Hz.  I seem to recall that the 8-inch SW-8-16FR will work OK up to 200 Hz. So I am thinking about a single (or maybe TWO) SW-8-16FR open baffle with the electrostatic array.  I will be getting the array first and making some measurements to see if it REALLy works OK crossed over at 200 Hz.  I have some DSP crossovers to use for experimenting, and will see if the thing actually works OK down to 200 Hz.

SO- will the SW-8-16FR be a good BASS DRIVER (up to 200 Hz)- or is it only good below 100 Hz?

And which servo amps should I use?

I am thinking to use a single SW-8-16FR per side because the electrostatic array is not really capable of high SPL and this is for a small room.  If it seems to need it, I could add a second SW-8-16FR per side.

Danny Richie

  • Facilitator
  • Posts: 12161
    • http://www.gr-research.com
Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #1 on: 11 Dec 2015, 03:08 pm »
Both the SW-08's and SW-12's will play up to 300Hz. But for your application the 12's will have the output capability that you need.

I'd go with a pair of the SW-12-08FR woofers per side and a pair of the A370PEQ amps. 

milosz

Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #2 on: 12 Dec 2015, 12:16 am »
A pair of 12 inch woofers seems like overkill for a 7 inch x 17 inch panel, even if they are open baffle, don't you think?

Danny Richie

  • Facilitator
  • Posts: 12161
    • http://www.gr-research.com
Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #3 on: 12 Dec 2015, 01:29 am »
A pair of 12 inch woofers seems like overkill for a 7 inch x 17 inch panel, even if they are open baffle, don't you think?

Oh, I didn't realize that your panels were tiny. You could go with three 8's but you are at about the same price.

But then again I used six of the 12" woofer in an open baffle for the bottom end to a pair of our LGK 1.0's (3" full range drivers) and it was great.

mlundy57

Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #4 on: 12 Dec 2015, 02:07 am »
A pair of 12 inch woofers seems like overkill for a 7 inch x 17 inch panel, even if they are open baffle, don't you think?

How large is your room and what level do you listen to your music at, both average SPL and peaks?

Mike

milosz

Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #5 on: 12 Dec 2015, 04:37 am »
How large is your room and what level do you listen to your music at, both average SPL and peaks?

Mike

These are intended for a small room- 10 x 12 or something along those lines.  I often listen at lower levels, ~85 dB peaks; but of course I can also listen at levels up to the point where the system shows strain.... so I think it all really depends on these panels.  I do not have them yet.  I have no experience with them, they are ER Audio (Australia) model 440 panels.  Once I get them and do some testing I'll have a better idea of their capability in terms of SPL and how low in frequency they actually work.  I've read that they can be crossed over at 200 Hz with just a capacitor (which would be a first order filter) but I'll have to measure them before I accept that.

I should mention that I have a lot of very good speaker systems (rebuilt ESL-57's, DEQX triamped Magneplanar MG 3.6's, etc) and so these are more of a the-fun-is-in-the-building project rather than a these-will-be-my-main-speakers project. I always wanted to make an ESL hybrid and I've been intrigued with the GR open baffle servo woofers so this looked like a chance to try both.

After reading the advice here I have a picture of a panel-plus-single-12" idea, since everyone seems to be saying that the output of the 8" driver is not very high.  You know I just can't imagine that a pair of these small panels is going to be able to produce 100 dB SPL plus levels at 200~400 Hz even in a small room.  I've read they have a larger-than-usual excursion for an ESL, so maybe they can.  But it all remains to be seen.  Or, rather, heard.

Danny Richie

  • Facilitator
  • Posts: 12161
    • http://www.gr-research.com
Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #6 on: 12 Dec 2015, 05:07 am »
You could go with a single SW-12-08FR woofer on each side and drive it with the HX300 amp. It is a lower powered and lower priced servo amp. But it is more then plenty of power for a single 12 in an H frame.

milosz

Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #7 on: 12 Dec 2015, 05:47 am »
You could go with a single SW-12-08FR woofer on each side and drive it with the HX300 amp.

That sounds like good advice.

Once I get the panels and test them I will post more.

bdp24

  • Full Member
  • Posts: 883
Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #8 on: 12 Dec 2015, 06:32 am »
These are intended for a small room- 10 x 12 or something along those lines.  I often listen at lower levels, ~85 dB peaks; but of course I can also listen at levels up to the point where the system shows strain.... so I think it all really depends on these panels.  I do not have them yet.  I have no experience with them, they are ER Audio (Australia) model 440 panels.  Once I get them and do some testing I'll have a better idea of their capability in terms of SPL and how low in frequency they actually work.  I've read that they can be crossed over at 200 Hz with just a capacitor (which would be a first order filter) but I'll have to measure them before I accept that.

I should mention that I have a lot of very good speaker systems (rebuilt ESL-57's, DEQX triamped Magneplanar MG 3.6's, etc) and so these are more of a the-fun-is-in-the-building project rather than a these-will-be-my-main-speakers project. I always wanted to make an ESL hybrid and I've been intrigued with the GR open baffle servo woofers so this looked like a chance to try both.

After reading the advice here I have a picture of a panel-plus-single-12" idea, since everyone seems to be saying that the output of the 8" driver is not very high.  You know I just can't imagine that a pair of these small panels is going to be able to produce 100 dB SPL plus levels at 200~400 Hz even in a small room.  I've read they have a larger-than-usual excursion for an ESL, so maybe they can.  But it all remains to be seen.  Or, rather, heard.

Beside the extra output a pair of woofers (either 8" or 12") per side provides over a single, there is another benefit to be gained by using a pair---employing them mounted in the opposite-facing/opposite-polarity dipole fashion: The OB/Dipole sub will then have the same figure-of-8 radiation pattern and room-loading characteristics as the ESL. Yes, the wavelengths of low frequencies are so long as to make bass omnidirectional, but a dipole sub is still better than non-dipole for use with a dipole speaker because: 1- The sub has a null at either side of the H- or W-Frame (a result of the opposite-polarity waves from the front and backing meeting at the sides, causing cancellation (+1 plus -1=0), as does the ESL. Those side-nulls allow the sub to be placed right next to either a side wall or the ESL itself (or both) without a sonic penalty. The sub can even be positioned laying down, for use as a base for the ESL if you so desire (with some form of isolation between the two, of course!); and 2- The drop-off in output of a dipole and a non-dipole differ from one another. When you set a balance between a non-dipole sub and a dipole main speaker, that balance is so at only one distance from the pair, as the output of the two changes with distance at a different rate relative to each other. With the dipole sub/dipole speaker pairing, it remains constant as listening distance changes. That's a big deal! The Finnish company Gradient made an OB/Dipole sub in the 80's specifically for the Quad ESL63, and it worked great for those reasons and others (decreasing the excursion of the ESL diaphragm for one, thus reducing distortion and increasing maximum SPL possible from the Quad). And that was without the Rythmik Direct Servo Feedback and the superior GR Research driver!

Once you have heard the OB/Dipole Sub with your little ESL panels, I'll bet you'll want to try them with your Quad 57's, with which they meld beautifully. I use a pair (each with two 12's and an A370 amp) with those Quads, as well as with a pair of magnetic planar speakers (though I have a pair of Magneplanar Tympani T-IV's, I haven't had the subs and them set-up together. I use the subs in place of the stock woofers in the Eminent Technology LFT-8b, crossed-over at 180Hz). Congratulations---you have discovered THE sub for use with any and all dipole/panel loudspeakers!

milosz

Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #9 on: 12 Dec 2015, 06:57 am »
A single driver mounted on an "H" open baffle panel is also a dipole.  You don't need two drivers to make it a dipole.

The ESL panel is just one driver, open front and back. It's a dipole.  (You CAN enclose the backwave of an electrostatic panel.  Janszen does this in their current line of speakers.  They have electrostatic panels but they are NOT dipoles.  See http://www.janszenloudspeaker.com/

A single woofer mounted on an panel open front and back is the same thing, just a different diaphragm shape and a different kind of motor.

I do plan to augment my Magneplanars with two dual-12" open baffle servo subs at some point, but not just now. 

mlundy57

Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #10 on: 12 Dec 2015, 08:15 pm »
These are intended for a small room- 10 x 12 or something along those lines.  I often listen at lower levels, ~85 dB peaks; but of course I can also listen at levels up to the point where the system shows strain.... so I think it all really depends on these panels.  I do not have them yet.  I have no experience with them, they are ER Audio (Australia) model 440 panels.  Once I get them and do some testing I'll have a better idea of their capability in terms of SPL and how low in frequency they actually work.  I've read that they can be crossed over at 200 Hz with just a capacitor (which would be a first order filter) but I'll have to measure them before I accept that.

I should mention that I have a lot of very good speaker systems (rebuilt ESL-57's, DEQX triamped Magneplanar MG 3.6's, etc) and so these are more of a the-fun-is-in-the-building project rather than a these-will-be-my-main-speakers project. I always wanted to make an ESL hybrid and I've been intrigued with the GR open baffle servo woofers so this looked like a chance to try both.

After reading the advice here I have a picture of a panel-plus-single-12" idea, since everyone seems to be saying that the output of the 8" driver is not very high.  You know I just can't imagine that a pair of these small panels is going to be able to produce 100 dB SPL plus levels at 200~400 Hz even in a small room.  I've read they have a larger-than-usual excursion for an ESL, so maybe they can.  But it all remains to be seen.  Or, rather, heard.

This is about the same size as my listening room and about the same levels I listen at. I started out with three 8's in H-Frames with HX-300 amps. Under these circumstances they worked well. The only negative I saw was that I couldn't get audible bass below ~ 25Hz. However, when I set them up in my larger living room (20'x25') with the listening position ~10' from the speakers the HX-300 amps would start clipping above 100dB at the listening position. Now that's some pretty serious SPL's (~112dB at 1M) but the clipping might be an issue for some. You could use the A370PEQ amps instead of the HX-300's and would not have to worry about clipping. However you would have to be careful not to bottom out the 8" drivers. Plus, three 8" drivers and an A370PEQ amp costs more than two 12" drivers and an A370PEQ amp. So if I were going to step up to the A370PEQ amps there would have to be a real compelling reason for using three 8's instead of two 12's.

I have recently switched the three 8's w/HX-300 amps to two 12's w/A370PEQ amps. Even in my smaller listening room I prefer the two 12's. The 12's play deeper (audible bass down to 20Hz) with more authority and sound fuller, smoother and more effortless than the 8's. Initially I thought the 12's would be overkill in this small room but that is not the case. The do not overpower the room. They just sound more right to me.

This is a long way of saying I agree with everybody else. Unless you have some major space limitation that would absolutely prohibit the extra 4" of cabinet width go with the 12's and A370PEQ amp. You will be glad you did.

Mike

bdp24

  • Full Member
  • Posts: 883
Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #11 on: 12 Dec 2015, 11:15 pm »
A single driver mounted on an "H" open baffle panel is also a dipole.  You don't need two drivers to make it a dipole.

The ESL panel is just one driver, open front and back. It's a dipole.  (You CAN enclose the backwave of an electrostatic panel.  Janszen does this in their current line of speakers.  They have electrostatic panels but they are NOT dipoles.  See http://www.janszenloudspeaker.com/

A single woofer mounted on an panel open front and back is the same thing, just a different diaphragm shape and a different kind of motor.

I do plan to augment my Magneplanars with two dual-12" open baffle servo subs at some point, but not just now.

You are absolutely correct, sir! Regarding which amp to use, the A370 is available with a shelving circuit installed to compensate for the acoustic roll-off endemic to OB subs. Is the circuit available in the HX300 as well?
« Last Edit: 13 Dec 2015, 02:58 am by bdp24 »

mlundy57

Re: Which amp to use with SW-8-16FR OB driver? & 200 Hz?
« Reply #12 on: 13 Dec 2015, 04:06 am »
You are absolutely correct, sir! Regarding which amp to use, the A370 is available with a shelving circuit installed to compensate for the acoustic roll-off endemic to OB subs. Is the circuit available in the HX300 as well?

Yes the HX-300 also and just like the A370's Brian has to install it when an OB version is ordered.