Any 8" servo subs on the horizon?

corndog71 · « **on:** 19 Jun 2009, 12:34 am »

Just curious. I thought I read it somewhere in here a while back.

Danny Richie · « **Reply #1 on:** 19 Jun 2009, 01:06 am »

I have been considering having some made for open baffle use (high Q versions) for narrow profile open baffle designs. I haven't moved forward with it yet though.

I have something else that I am trying first.

woofersus · « **Reply #2 on:** 19 Jun 2009, 04:34 pm »

I would love to see an 8" or 10" to allow more easy integration into speakers as fantastic midbass drivers. The size would make the cabinet easier, and a smaller enclosure requirement would be a big help too. Aside from that, there are subwoofer applications in which a compact 10" or 8" design would be desirable - in my small studio for example, where I currently have an AV123 ULW-10.

Danny Richie · « **Reply #3 on:** 19 Jun 2009, 05:01 pm »

I think I have something that will work for you without getting too small and not be able to move enough air.

I have a smaller follow up model, to what was going to be called the Venue, in the works.

I have the P-Audio BM8 CXA on hand for the upper section. It actually has the smoothest response of all of their co-axial drivers. It will be in open baffle of coarse.

http://www.loudspeakersplus.com/html/paudiocoax.html

Below it I will have a pair of the Eminence Acoustinator N2012's:

http://www.eminence.com/pdf/acoustinator-n2012.pdf

These are not only great for open baffle applications, but they have a small size but high power Neo motor that will allow them to be twisted about 45 degrees in an H or W type frame that will keep the front baffle width down to about 10" wide.

They aren't going to be servo controlled though. I am trying to keep the cost down.

I do have a special plate amp on hand though with a shaped output and a rumble filter to kill all below 20Hz. I tested the amp already and it looks good so far.

Now I just have to build a test box... I hate building test boxes!

TRADERXFAN · « **Reply #4 on:** 19 Jun 2009, 07:06 pm »

Sounds very interesting.
Are you saying that you would angle the woofer, left to right, then? It's hard for me to picture this.

Where do you think the low end rolloff would be on the coaxial for this one?

Danny Richie · « **Reply #5 on:** 19 Jun 2009, 08:20 pm »

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Are you saying that you would angle the woofer, left to right, then? It's hard for me to picture this.

Take the two 12" woofers standing up on a baffle so that one is over the over (vertical stack). Take the top woofer and twist it 45 degrees by moving the left side forward and the right side back. Then take the lower one and twist it 45 degrees moving the right side forward and the left side back.

Put side panels on it like this W frame:

http://www.gr-research.com/images/obtest.jpg

Now the total inside diameter from the left side panel and the right side panel should be about 9". Unlike the woofer pictured, the Acoustinator woofers have a small Neo motor that doesn't hit the wall or stick out a long way when you twist it.

Get it?

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Where do you think the low end rolloff would be on the coaxial for this one?

We'll see.

corndog71 · « **Reply #6 on:** 20 Jun 2009, 12:58 am »

Quote from: Danny on 19 Jun 2009, 05:01 pm

Now I just have to build a test box... I hate building test boxes!

After all of the trouble I went through to build my sealed servo sub cabinet, I can certainly appreciate that comment.

This new OB design sounds great! Especially for us poorer folks. I love the venue and PDR kills me with all of his gushing, but dang it's a chunk of major coin. Maybe if I were single I could reach it... and had a better apartment...

who knows, maybe someday.

Danny Richie · « **Reply #7 on:** 20 Jun 2009, 02:19 am »

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I love the venue and PDR kills me with all of his gushing, but dang it's a chunk of major coin.

Yep, I understand. I am hoping that this one will come in at about half of that and no more than $1,200 tops.

HT cOz · « **Reply #8 on:** 22 Jun 2009, 03:36 pm »

Quote from: Danny on 19 Jun 2009, 05:01 pm

I have the P-Audio BM8 CXA on hand for the upper section. It actually has the smoothest response of all of their co-axial drivers. It will be in open baffle of coarse.

Could these work as In-Ceiling Speakers?

woofersus · « **Reply #9 on:** 22 Jun 2009, 05:08 pm »

Sounds very unique. It'll be interesting to see how it comes out.

Stereodude · « **Reply #10 on:** 23 Jun 2009, 11:22 pm »

I'd rather have an 8 ohm servo driver with large Vd. Like an 8 ohm 15" driver with 20+ mm of x-max.

Danny Richie · « **Reply #11 on:** 24 Jun 2009, 12:24 am »

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I'd rather have an 8 ohm servo driver with large Vd. Like an 8 ohm 15" driver with 20+ mm of x-max.

Two things really work against that.

1) The bigger it is the higher the moving mass. This means it is harder to get it to stop moving.

2) The long exertions create more pressure on the cone to flex and distort causing distortion to increase.

Stereodude · « **Reply #12 on:** 24 Jun 2009, 02:19 am »

Quote from: Danny on 24 Jun 2009, 12:24 am

Two things really work against that.

1) The bigger it is the higher the moving mass. This means it is harder to get it to stop moving.

2) The long exertions create more pressure on the cone to flex and distort causing distortion to increase.

Well, there are a lot of companies making large drivers with lots of excursion. They don't all suck. If Brian or yourself aren't interested in that market I guess there are lots of other choices. Unfortunately none of them have the advantage of the directservo system.

stevenkelby · « **Reply #13 on:** 24 Jun 2009, 02:27 am »

Why would you want a 15" driver with high x-max, when 2 smaller drivers sound better and play louder?

Stereodude · « **Reply #14 on:** 24 Jun 2009, 02:53 am »

Quote from: stevenkelby on 24 Jun 2009, 02:27 am

Why would you want a 15" driver with high x-max, when 2 smaller drivers sound better and play louder?

No, I want 4 15" drivers with high x-max with 2 amps. Do you still think I should go with 8 12" drivers and 4 amps instead?

stevenkelby · « **Reply #15 on:** 24 Jun 2009, 02:56 am »

Quote from: Stereodude on 24 Jun 2009, 02:53 am

No, I want 4 15" drivers with high x-max with 2 amps. Do you still think I should go with 8 12" drivers and 4 amps instead?

Ah fair enough. Tough call. The 8 x 12" will sound better and play louder for sure though!

Danny Richie · « **Reply #16 on:** 24 Jun 2009, 03:27 am »

If you really, really want four 15" woofers that have servo control then buy them. Brian (Rythmik) sells a servo 15.

BTW, high SPL is not that hard to make.

If you want speed and accuracy with a flat response to 20Hz then I think the lighter weight, paper cone, 12" servo woofers will top the list.

Stereodude · « **Reply #17 on:** 24 Jun 2009, 06:16 pm »

Quote from: Danny on 24 Jun 2009, 03:27 am

If you really, really want four 15" woofers that have servo control then buy them. Brian (Rythmik) sells a servo 15.

Brian's 15's are only 4 ohms, and they didn't exactly blow my skirt up when I modeled them.

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BTW, high SPL is not that hard to make.

If you want speed and accuracy with a flat response to 20Hz then I think the lighter weight, paper cone, 12" servo woofers will top the list.

FWIW, I want a flat response to 10Hz. I guess I should build the theater first and worry about the subs for it later.

Danny Richie · « **Reply #18 on:** 24 Jun 2009, 07:23 pm »

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Brian's 15's are only 4 ohms, and they didn't exactly blow my skirt up when I modeled them.

Servo subs won't model like a typical woofer unless they are used without the servo. The servo system takes control of the driver and makes the T/S measurement irrelevant.

Stereodude · « **Reply #19 on:** 24 Jun 2009, 08:38 pm »

Quote from: Danny on 24 Jun 2009, 07:23 pm

Servo subs won't model like a typical woofer unless they are used without the servo. The servo system takes control of the driver and makes the T/S measurement irrelevant.

That's not exactly true. You can still model the maximum output of the enclosure amongst some other things.

See Brian's response last time the question of modeling a servo sub came up.