[studley]

I have a pair of Quad 989  ESLs and I'm thinking of adding a subwoofer to get down below 40Hz.  However I've been reading a lot recently about the superiority of active crossovers and so that is the route I would want to take for the sub.  Ideally I would therefore need a sub that does not incorporate any frequency filter or passive Xover. 

Anyone know of any decent subs like this, or do I need to go DIY, eg the Linkwitz Thor?

[woodsyi]

A lot of subs are being equiped with plate amps that has lowpass and eq.  The real issue may be whether you want to subject your Quads to an active highpass.  Depending upon the rolloff characteristics of your stats, you may not need a high pass.  I use a two way Marchand XM9 to highpass a pair of Soundlabs at 70Hz and bring in 2 passive SV subs.  Any passive subs would fit your need.

[ted_b]

A passive sub, a Crown amp (or similar) and a Velodyne SMS-1 is a nice inexpensive solution.  The SMS-1 is a great $599 VERY active crossover and bass management system (same room correction solution they use internally in their DD series).  It allows great integration to the system and shows, realtime, the potentially huge changes occuring when you delicately move a crossover point, physicaly move the sub, change phase or polarity, etc.  It's infinitely flexible and does a good job of measuring and solving the room/sat/sub integration.

[bgewaudio]

I have a Velodyne CHT12 ($699.99) that I got from futureshop, best one they had at the time.  This sub empoly's a 170 watt/rms amplifier, built in anti clipping device and over exertion protection, phase invert switch, High/low pass crossover, auto on/off switch.

There is also a subwoofer direct/x-over switch which allows you to either set the crossover on your processor, and send the signal directly to the sub to disengage the subs xover, or switch to x-over and the sub will bypass the processors x-over and allows you to use the low pass in the sub.  Cool feature and all but I prefer to use the x-over in the sub.

Not a bad Sub overall, more recommended for HT than 2/ch, could have a little more control.  If you're looking for a more musical sub, look at their DD series!

[Bob Reynolds]

Studley,

You may find this of interest: http://www.mkprofessional.com/bass_mgmt.htm

In my experience you are on the right track. I highly recommend M&K subwoofers and their bass management controllers. Their subs have a setting that by-passes any internal filters - they assume the xover will be external.

I side with Robert E. Greene in his belief that even inexpensive electronics distort the signal so little compared to speakers that it's a non issue. So, I recommend high-passing the main speakers. Even Richard Vandersteen with his full-range Model 3 uses a high-pass filter when employing a sub. Besides lessening the distortion from the speakers, there is also the benefit of having the bass emanate from the corner away from the main speakers. You can read several of REG's articles on this at his web site: http://www.regonaudio.com/

-- Bob

[studley]

Many thanks to all those who have responded, you've given me plenty to research and think about.

Keep it coming anyone else out there with anything to add!

[macrojack]

Until I upgraded my speakers, I used Zu Druids with Zu's Mini Method sub. Since the Zu presentation is so often likened to QUAD, I often wondered how it might interface with your speakers. The Mini Method has 2 forward firing tens and is very quick. Give Zu a call and ask them about the matchup. They offer a 60 day money back deal, so it won't cost much to try one if you think it could be what you need after talking with them.

[amplifierguru]

Hi Studley,

If you're interested in an active crossover for your Quads/sub, I have a design that is very flexible. It is not listed on my website but I have done a few PCBs and built 2. I have one going in an 8 channel system later this week. 

The design takes L,R main channels and filters them at 12dB/octave at, say 120Hz and outputs that to the main system.
It also sums L,R channels independantly and has configurable high pass with or without boost (say 20Hz) and low pass at the crossover (120Hz) and sub-gain all on a 2" x 3" double sided, ground planed, through hole plated PCB with discrete 80dB+ regs. It can be powered from a 15Vac wallwart or +/- 18 to 23V. Chips are OPA4134 FET cascode Burr Brown. I haven't written instructions yet . It can be LW or Butterworth, or other response.

Cheers,
Greg

Contact me if you're interested.

[studley]

Greg
I'll pm you
Ian

[Wayne1]

FWIW, The VMPS subs were first designed to mate with Quad ESL-63s.

They are available in either passive or active configuration.

You can add an active X-over and power amps. Have the speaker built using a passive filter, so all you need to do is add a power amp.
Third option is to use a power amp built into the speaker with an active crossover and parametric EQ.

BTW, I am a dealer for VMPS and I use a Larger sub with separate power amp and active digital EQ and crossover in my system.

[Psychicanimal]

I am a dealer for VMPS and I have an addiction for very muscular women.

Good evening Wayne. Thanks for sharing.


Back to topic, there's three issues I'm concerned with subwoofer integration (ie, invisibility):

1) tonality
2) speed/control
3) phase coherency

The subwoofer's tonality must match closely that of the speakers and it must match their speed in a controlled fashion.  This has to do with several factors (sub amps' rise time & damping factor as related to subwoofer's suspension PLUS current driving abilities of the amps). Placement and proper x-over frequency selection are important in achieving phase coherency along with a x-over slope of 6, 24 or 48 dB/octave.  All these must be addressed, otherwise you'll have trouble.

Right now I'm working on my car stereo and am going to use Memphis Audio carbon fiber 5 1/4" mid-bass drivers.  The sub will be an 8" dual voice coil Bazooka driven by an Orion 50W/ch amp.  The Bazookas have 102 dB efficiency, 2" voice coils and a 36 oz magnet.  The amp, albeit 'small', has a damping factor of 300.  A homemade three conductor braid of 12 ga solid core copper (1 for + terminal, 2 for - ) will link them.  Short of putting a carbon fiber woofer in a box (which I don't want in my car's trunk) that's the best solution I can come with.  This is just an example to help you visuallize my approach.  In my home stereo I use a Dan Wright modded Marchand X9 Deluxe crossover with Kenwood L07 M monoblocks driving NHT 10" subs via home brewed solid copper speaker wire.  The subs are completely invisible and the amps deliver enough current to arc weld with them!

***

[studley]

Thanks Wayne I'll have a look at the  VMPS.

Can you tell me a bit more about the active xover and digital EQ you are using?

[Thebiker]

I'll join Bob Reynold's endorsement of the M&K systems.  I've been using their V125 for @ 9 years and am extremely pleased with it overall.

It was originally purchased to be part of my M&K home theater, but has since been moved to duty with my main 2 channel rig (Cary SLI-80 pushing JM Lab Cobalt 816s).  The sub does not lag behind, which has amazed me considering the response speed of the 816's.

[Wayne1]

http://www.qscaudio.com/products/dsp/dsp4/dsp4.htm

I use a QSC DSP-4 plugged into a QSC DCA-3422 power amp

http://www.qscaudio.com/products/amps/dca/dca2/dca2.htm

I have used this combo with VMPS subs for a number of years now.

It was used at the Midwest Aduio Fest where Marbles stated:"That was a GREAT sounding room, with some of the best bass I have heard in a room that size...That was with VMPS 626's and a larger sub.  One front end was a Teres Turntable."

The 626s were used full range and the sub just rolled in under them.

I am also going to be checking out the R-DES unit from AV123.com in the next couple of weeks





http://www.av123.com/products_product.php?section=processors&product=31.1

[Psychicanimal]

Sorry Wayne,

For some weird reason I confused you
 with John Casler--he's the one who's into muscular women...