[SteveRB]

Hello,

I've had servo subs before with open baffle -- they sound great.

I am currently looking for sub woofer options for pairing with custom mid-bass horns. Is there any direct experience with the servo sub and  horn dynamics?

I have a relatively small space and do not play music super loud. Any suggestions as to models, size , quantity to keep up with a system that is around 110db sensitive?

Thanks.

[lokie]

I've been contemplating something similar and wondering how high I can go w the OB subs and stay coherent... Also concerned how nice the servo amps will play with my tube preamp (noise, hum etc). Would love to pull off the low pass at line level to take the bass load off my 4 watt amps.

Too expensive to experiment (on my dime anyway). Sure would be cool if someone has been around the block w integrating  a 100db or north system. My suspicion is that it seems like a great idea in theory but may be very difficult to pull off successfully in practice. One last note on this, is that, I think Danny has impressed upon me a desire for his customers to succeed and with his formidable knowledge and guidance on the subject, it might just be doable.

Curious as to your mid-bass horns that play 110db in a small space. I'm thinking back loaded, which I think would have problems w  timing and coherency.

[DaveC113]

That's how Avantgard does it and their latest speakers seem to integrate pretty well. I'm thinking DSP will help, but you'll want to use a driver that isn't a subwoofer if you need it to play up 250+ Hz and not sound slow, imo....  You want a lighter cone, low inductance and a powerful motor, maybe a 4ohm VC to match with a powerful D amp like the new NCore NC500 modules, which would give you 700W into 4 ohms. I'm actually thinking of using two different 15s, one with a very light cone and Fs around 40 Hz like the JBL 2226 or AE TD15M along with a driver with lower Fs and a heavier cone to handle under 100 Hz or so, a servo sub could probably handle this pretty well but imo it'll fall short at higher frequencies, and it won't have the "slam" of a driver like the JBL 2226/ AE TD15M.

[SteveRB]

110db may have been a slight exaggeration.

lokie and I are on similar paths. I live without low bass in favour of my horns, tubes, and analog set up. The last thing I want to do is put DSP in the chain. I am ok with a little processing on the lowest octaves. The mid-bass horns are decent to about 90Hz, after that they are simply a 15" woofer in a small sealed box. I don't have the space for 8' folded bass horns.

I know that Volti Audio has a large sub they sell with the'r Klipsch style horns. To me, it just looks like huge displacement to 'fill in' bass. I would hope for something a little 'faster' to bring to my room.

My horns:

[SteveRB]

Also, yeah. Ordering a 12" woofer, amp, plywood, cables and build time will run me $1,000CDN. It would be nice to have someone with any experience chime in first.

[bdp24]

Danny has used his OB/Dipole sub with a pretty high-sensitivity 15" P-Audio driver , in his Super-V loudspeaker (you can see it in the "Archived Models" section on the GR site). A pair of 12" Servo woofers and an A370 plate amp on each channel will cost you about $1600 (depending on shipping), plus the cost of a pair of W- or H-frames to put the woofers in. It can be crossed over to up to around 300Hz, I believe. Give Danny a call, he'll tell you all about it. Or look at the woofer on the website (there are two versions of the 12" OB woofer, 16ohm and 8ohm, plus a 16ohm 8"), where you can see the plans for the frames.

[SteveRB]

Thanks,

The problem for me right now is $1500 is more like $2K in Canada for a bit of an unknown...

[ebag4]

Also concerned how nice the servo amps will play with my tube preamp (noise, hum etc). Would love to pull off the low pass at line level to take the bass load off my 4 watt amps.

Although not using horns I do this with my Bottlehead 2A3 amp.  I jump the input of the amp to a pair of RCAs and use them as the output to my GR servo sub amps, no issues with hum at all, of course every system is different. I then have a pair of caps in series after the RCA input to hi pass the Bottlehead, works great.  Currently driving 94dB Wedgies but have also driven 96dB V1s.

Best,
Ed

[Danny Richie]

You really don't have to look at this from the standpoint of will the servo subs match the SPL levels and dynamics of a 110db horn. Look at it from the standpoint of what SPL level am I going to be playing these horns. And you have a small space. So how loud will you be playing those horns? Probably not real loud.

Yes, a pair of the servo subs on each side will keep up with high SPL levels of 97 and 98db speakers playing loud in a big room. Matching the levels is easy. It is just a matter of turning up the volume knob on the servo amp until the levels match.

And these will play up to 300Hz crossover points and will easily match the dynamics of the horns.

And if your tube pre-amp isn't noisy driving your main power amps and high sensitivity speakers then it won't be noisy on the servo subs.

Your real issue to consider is can you pull them far enough out into the room for them to work for you in a small room. You might need to consider sealed box servo subs. I have that solution for you as well.

[SteveRB]

Thanks Danny,

Would a single 12" sealed work? or would I require a stereo pair?

I cannot bring OB subs far enough into the room.

[Danny Richie]

Thanks Danny,

Would a single 12" sealed work? or would I require a stereo pair?

I cannot bring OB subs far enough into the room.

For the size of your room a single sub will be fine if you are crossing no higher then 80Hz. If you have to play up higher than that then your really need one per side.

[lokie]

Your real issue to consider is can you pull them far enough out into the room for them to work for you in a small room. You might need to consider sealed box servo subs. I have that solution for you as well.

Do you mean by "far enough' as to get the drivers of the sub and the mains to physically line up with each other?  And  the box subs offer more flexibility somehow through the servo amps controls? And how much flexibility?   

[Danny Richie]

Do you mean by "far enough' as to get the drivers of the sub and the mains to physically line up with each other?  And  the box subs offer more flexibility somehow through the servo amps controls? And how much flexibility?   

Open baffle woofers really need to be at least three to four feet out into the room. You can't push them up to the front wall.

Physically aligning them with the main speakers isn't a big deal. The wavelengths are long and easy to blend especially with a continuously adjustable phase control right on the servo amp.

The boxed sub is more flexible in that they can be placed right up on the wall.

[mlundy57]

Do you mean by "far enough' as to get the drivers of the sub and the mains to physically line up with each other?  And  the box subs offer more flexibility somehow through the servo amps controls? And how much flexibility?   

Oops, a little late with this post but I'll leave it anyway

Far enough into the room for OB subs means at least 3ft out into the room. I have dual OB subwoofers (one on each channel, also paired with 94.5 dB efficient Wedgies) in the man cave which is a small room (10' X 11' X 8'). In this room they are 3' off the front wall.  In my larger (20' X 25' X 8') living room they sound best 5' off the front wall. Their primary home is the man cave (repurposed child's bedroom).

I also have a sealed servo sub in the living room system. The sealed sub can be placed right up against the wall or out into the room, whichever works best. I used to have it right against the front wall but currently have it placed directly behind the sofa.

To sum up, OB subs need to be at least 3' off the front wall. Sealed subs can be right up against the wall.

These servo subs are the fastest, cleanest and most musical subs I have ever heard. To put it in perspective, these subs and amps are the same ones used in the Serinity Super 7's and in the triple driver H-Frame configuration that were paired with the LS-X OB line source that garnered "Best Sound Cost No Object" accolades at RAMF a couple years ago.

Mike

[Captainhemo]

If getting them out into the room is an issue,  you could always go with the U-Frame design which will  generate a null at the rear allowing you to keep them closer to the wall. 
I don't think you're going to reach your c/o point  with a sealed  sub (IIRC)

jay

[Danny Richie]

If getting them out into the room is an issue,  you could always go with the U-Frame design which will  generate a null at the rear allowing you to keep them closer to the wall. 
I don't think you're going to reach your c/o point  with a sealed  sub (IIRC)

jay

A U frame still acts like the H frame. The null is still at the midway point.

[Captainhemo]

A U frame still acts like the H frame. The null is still at the midway point.

 hmmm,  not sure what I was thinkiing of then... weren't the "greatest speaker stands" based on a U bafle  ?  I thought one of their traits was being able to place them up  close the wall

jay

[mlundy57]

hmmm,  not sure what I was thinkiing of then... weren't the "greatest speaker stands" based on a U bafle  ?  I thought one of their traits was being able to place them up  close the wall

jay

Jay,

If I recall, those did not end up working properly as OB but did work more like a big port when used with the standard version (sealed/ported) of the amp. So they are really a ported sub rather than an OB sub.

I don't know why that version didn't work out as OB while the Wedge cabinets did. Maybe Danny can enlighten us on the why two designs that look similar behave so differently.

Mike

[Captainhemo]

Mike,
That is sort of what I was getting at... don't  your  "wedge subs"  have a null at the rear ?
I realize that  first version didn't  end up  working out, but it was the idea  behind the wedge subs.....  I just thught the new  vesion  still  had the  nulls allowing them to  be fairly clsoe to the wall

jay

[mlundy57]

Mike,
That is sort of what I was getting at... don't  your  "wedge subs"  have a null at the rear ?
I realize that  first version didn't  end up  working out, but it was the idea  behind the wedge subs.....  I just thught the new  vesion  still  had the  nulls allowing them to  be fairly clsoe to the wall

jay

Jay,

Nope, definitely no null at the rear of the Wedges. These are OB and have to have the OB board in the amps.

The only thing I can think of is that the wedge shape has a lot larger opening than the best speaker stands and that opening is flared due to the angles. That's only a guess though.

Mike