Which sub do you have in HT system?

[OVERKILL]

Originally Posted By: grampi

As far as the amp goes, each VC will only be getting 215 watts....though the amp is capable of producing a lot more power than that, voice coil impedances and load requirements for the amp prohibits connecting it in such a way that would unleash all of that power...so the amp will have easy duty...and my AVR already has a low pass filter on the LFE output set at 80 hz (I'm sure most AVRs have them)...I'm not sure what the roll of rate is, but it's probably at least 12 db per octave...the amp has one too, I can use either one I choose...


If we are talking about the Crown unit, you can run it bridged mono @ 4ohms based on the spec sheet.

You can only wire it up three ways:
1. Stereo: Each voice coil fed separately from the amp, 8ohm load
2. Mono parallel: Positive and negative posts on each coil are bridged with a single feed back to the amp from each bridge. 4ohm load
3. Mono series: Positive on VC1 into negative on VC2, negative from VC1 into the amp, positive from VC2 into the amp. 16ohm load

Each configuration gives you a different amount of peak power. Personally, I'd go with the 4ohm bridged configuration. If you are using an amp that will drive a 4ohm load bridged, why not take advantage of that?

 

[grampi]

Originally Posted By: OVERKILL
Originally Posted By: grampi

As far as the amp goes, each VC will only be getting 215 watts....though the amp is capable of producing a lot more power than that, voice coil impedances and load requirements for the amp prohibits connecting it in such a way that would unleash all of that power...so the amp will have easy duty...and my AVR already has a low pass filter on the LFE output set at 80 hz (I'm sure most AVRs have them)...I'm not sure what the roll of rate is, but it's probably at least 12 db per octave...the amp has one too, I can use either one I choose...


If we are talking about the Crown unit, you can run it bridged mono @ 4ohms based on the spec sheet.

You can only wire it up three ways:
1. Stereo: Each voice coil fed separately from the amp, 8ohm load
2. Mono parallel: Positive and negative posts on each coil are bridged with a single feed back to the amp from each bridge. 4ohm load
3. Mono series: Positive on VC1 into negative on VC2, negative from VC1 into the amp, positive from VC2 into the amp. 16ohm load

Each configuration gives you a different amount of peak power. Personally, I'd go with the 4ohm bridged configuration. If you are using an amp that will drive a 4ohm load bridged, why not take advantage of that?


This amp makes 1100 watts bridged into 4 ohms, but the sub only handles (only lol!) 750. Bridging the amp into a 16ohm load will yield no more amp power, and maybe even less than just running stereo into 8ohms...215 wrms per VC should be plenty...plus the higher impedance keeps the dampening factor higher and is easier on the amp...

 

[OVERKILL]

Yeah, we previously discussed it having a max power of 1,100W bridged. But it will never see that power level, as sleddriver has also mentioned. And yeah, the 16ohm setup wouldn't make sense, I just listed it for the sake of a complete list

There is always the option of just trying it both ways as well, and see if you notice a difference. Food for thought.

 

[grampi]

Originally Posted By: OVERKILL
Yeah, we previously discussed it having a max power of 1,100W bridged. But it will never see that power level


That depends. Even if it didn't, the power level would certainly exceed the max of the driver...

 

[OVERKILL]

Originally Posted By: grampi
Originally Posted By: OVERKILL
Yeah, we previously discussed it having a max power of 1,100W bridged. But it will never see that power level


That depends. Even if it didn't, the power level would certainly exceed the max of the driver...


You think you'd hit 750W power levels?

 

[grampi]

Originally Posted By: OVERKILL
Originally Posted By: grampi
Originally Posted By: OVERKILL
Yeah, we previously discussed it having a max power of 1,100W bridged. But it will never see that power level


That depends. Even if it didn't, the power level would certainly exceed the max of the driver...


You think you'd hit 750W power levels?


I'd probably have to have the volume level pretty high and/or there'd have to be some pretty high transients in the movie/music, but yeah, with the amp wired in mono into a 4 ohm load, I think it would exceed 750 watts....subs can and do draw a tremendous amount of power...

 

[OVERKILL]

Originally Posted By: grampi
Originally Posted By: OVERKILL
Originally Posted By: grampi
Originally Posted By: OVERKILL
Yeah, we previously discussed it having a max power of 1,100W bridged. But it will never see that power level


That depends. Even if it didn't, the power level would certainly exceed the max of the driver...


You think you'd hit 750W power levels?


I'd probably have to have the volume level pretty high and/or there'd have to be some pretty high transients in the movie/music, but yeah, with the amp wired in mono into a 4 ohm load, I think it would exceed 750 watts....subs can and do draw a tremendous amount of power...


Perhaps I underestimated the volume at which you listen to music, LOL! I've managed to make the SpeakerCraft go thermal a few times listening to Lindsay Stirling at higher volumes, but I've never had a movie do it, FWIW. I never hit the protection circuitry on the old Yorkville monster, but it was rated for 2,400W @ 4ohms bridged.

 

[sleddriver]

Originally Posted By: OVERKILL
Merry Christmas!

BTW, my aunt had 4x (IIRC) McIntosh power amps that came out of a huge home theatre (cinema) I think they were "rated" for 150W RMS. they had to weigh similar to your Sherwood. I always thought they would have worked well driving a sub.

The issue with my setup, not to go off on a tangent, is I'm using a car audio sub with an obscene power handling rating. My buddy won the IASCA Nationals with this sub in a Mercury Cougar years back. Two of them, in another box, he won SQ. He had a couple of huge amps bridged down to 0.5ohms feeding the pair of them. I remember one of the amps blowing up and it was rather impressive, LOL! I think that setup was 4K watts? Might have been more. Anyways, the sub is ridiculous, and so I've sort of settled on just feeding it with something adequate for my listening needs rather than trying to match its rating. I've thus far concluded that the SpeakerCraft isn't quite big enough, but is the right "style". If you've got any recommendations on something that can handle 4ohms bridged, I'm all ears

Edit: Would definitely be interested in those calculations

Wow...an aunt who appreciates fine audio! More women should consider careers in audio % acoustics. They are rare indeed...

Car audio subs are a whole animal unto themselves. They're built to withstand a lot of heat, with very stiff suspensions and very heavy cones. It's a fringe element to me. Reminds me of Quality, Price and Time on construction work: Pick two.

Pro-sound switching amps are designed to supply massive power for hours on end, in often hot&humid outdoor conditions....and survive. I'd think they would run at least on 220VAC or higher. Their high fans though make them noisy indoors in a home. Don't have any recommendations there.

Calculations: I'll refer you to Linkwitz' excellent site. Great bedtime reading for the audio engineer to learn from The Master himself. His active filter network designs are a work of art and designed ONLY for very specific drivers and the alignments he prefers. With the availability of powerful fast DSPs, plentiful RAM, we can take the equations, program a DSP and go that route. The signal from a digital high quality source is entirely kept in the digital domain. No more passive components between the amp & VC.

His work is truly state-of-the-art!

 

[OVERKILL]

I'm currently leveraging a Denon AVR-X4200 for DSP duty, which has some reasonably decent crossover configuration for the subwoofer setup. This then feeds the SpeakerCraft, which in turn feeds the sub. There is no passive component between the SpeakerCraft and the sub.

Your description of the Pro-Sound amp is entirely in-line with why I ditched the Yorkville for feeding the sub. It was loud (fan), drew a ton of juice, and wasn't triggerable. That's why I went looking for something else and a guy I know who does home theatre installs gave me the SpeakerCraft. It works quite well other than going thermal at the edge of my listening range, which I've tuned out by dropping the gain to the sub feed down a bit in the Denon.

I'll take a peek at that site.

 

[sleddriver]

The brilliance & art of Linkwitz with Thor is that he cancels the natural pole with a zero, then establishes a newer, lower pole to obtain a lower f3. Dunlavy did something similar but with passive filter networks.

Bullock wrote many articles on using an active filter network to "lift" the low end bass response on both sealed and vented designs. My custom stereo subs use this technique resulting in a 6th order alignment. Works very, very well when properly dialed in but requires measurement instrumentation to get it right.

Note these two techniques are different. Both require active filters however.

As you've discovered, the best way for dealing with a noisy amp is to move it into another room. Without a built-in trigger, you can rig one using a current-sensing torrid to enable remote off/on.

You can also greatly dimish fan noise by making sound bend 90° and lining the path with foam. You have to do this for both sides (air in & out) though. Many Euro vacuums, like the Fein I have, do this and exhaust the air directly at the ground...yet another 90° turn to the users ear. That's why they're so quiet.

I once experimented with this by taking my hot-dog-air-compressor outside the garage and set it against the outside back garage wall, 90° to the door opening only 4 feet away or so. Not having much air capacity, it was frequently cycling while in use....and very loud inside the garage even with the big car door open! This little trick resulted in a remarkable decrease in dB, even with the small access door remaining open and radiating in a qrtr sphere space.

This is the Science of Sound.

Finally, if you're experiencing overheating problems with your Denon, I'd suggest a small confuser muffin fan running at a lowered voltage, to blow air directly onto the heat sinks. Works wonders. I use this technique on the dragon (HK Citation 7 I refitted a few years back) and both the main power xnsfrmr & heat sink remain cool. I pulled 9V off one of the power rails to run a 12V fan, which lowers the noise.

Happy New Year!!

 

[OVERKILL]

Happy New Year!

Yes, I'm familiar with the 90 degree trick

I had thought about fabbing up my own remote trigger for the Yorkville but I got lazy....

I was just going to use a relay. But as I said, the SpeakerCraft fell into my lap and has been mostly sufficient for the duty, though it lacks the same level of output as the Yorkville unit.

To be clear, it isn't the Denon that's having heat issues, it has been entirely problem-free. It is the separate SpeakerCraft amp that is feeding the sub that goes into protection mode when really pushed. I tried adding active cooling to it, but that didn't seem to help. I believe I may actually be upsetting it with too low of impedance (despite its rating) but since it was free...

I'll likely upgrade it again at some point to something more appropriate, likely in-between the SpeakerCraft and the Yorkville.

When you say stereo subs, are you speaking in the colloquial sense or technically? I've heard of people literally doing stereo subs (not mono) but have not experimented with it myself as my knowledge on the subject indicated that bass is so non-directional to the listener that it generally wasn't worthwhile. And of course the source plays into this as well.

I will definitely be looking into the first part of your post further. This is really a topic you are far more into than I have been historically, so to say your posts have provided me with some homework would be a gross understatement

 

[sleddriver]

Ahhh...I understand...it's the SC amp having issues, not the Denon. If fan cooling it hasn't helped then the protection ckt could be triggered by too much low-freq information. These filters are a fine balance between protecting the spkrs and allowing lots of low-freq. infornation through. You can test this with a sine wave generator at sufficient amplitude to trigger the ckt. Don't load the amp with your spkrs though...use big resistors. Air/oil/water cooled if necessary.

If this amp is old, the elec. caps used could have drifted out-of-spec, thus throwing off the original filter resonant freq. The solution is to replace these caps with a quality, tighter spec part and see if the problem goes away. You can also use multiple caps in combination to spread the stastical value distribution and allow you to fine tune the freq.

Re: Stereo Subs. Yes mine are fed a stereo signal downstream of the active filter network, also stereo. Rationalle being that this active filter is necessary for their use and custom tuned. An off-the-shelf solution wouldn't work. Each cabinet has a pair of 12" woofers in a vented, heavily braced and lined box. I finally discovered the source of a very annoying harsh resonance that even appeared on a freq vs. impedance plot. It wasn't the boxes fault: It was due to the cheap, stampted drivers! The solution was they needed to be acoustically grounded. I'd tried everything else. Never encountered such a problem before though, so it was all very new ground....literally.

First 1-1/2 oct of bass is fairly non-directional. However great recording effects can take advantage of stereo subs. For example, Geddy Lee of Rush uses a stereo pickup on his bass. On some passages, you can hear the very deep, wide, open transparent bass as it's been recorded in stereo. A standard surround-sound receiver though would sum all lower bass below 80Hz (usually) and feed a sub a monoaural signal, thus loosing the effect.

The HK Citation is able to output a full-range signal to the main line-outs when properly configured. Furthermore, the mono-sub output can also be modified as well. But it's still a mono-signal. So my dual sub feed comes from a custom active filter network in stereo, not from the Citations mono-sub output.

See the difference? Movie soundtracks are quite different to audio tracks. Unless the later are all now being mixed for 5.1 playback. No one was doing this long ago however. One of many reasons why I still have my records & CDs.

I'm trying to think of the name of the Rush song...."about the function and the form. Everybody needs to deviate from the norm." Could it be called Mixed Feelings perhaps? His vocals trail off with "everybody needs to deviate...". Anyway, it has a great bass line that just growls with authority. You can easily hear the bass is stereo.

Finally, back to my set-up...I have two cabinets each with a pair of 12's (300mm), on opposite sides, fed with a stereo amplifier. Above 80Hz, the signal is tapered off at 12 dB/oct. These two do the heavy lifting so the MTMs above don't have to. This results in lower distorsion, greatly improved IMD and a wide, deep transparent sound.

The room is more equally loaded with two subs but also with dual drivers as their XYZ positions in space are different as well. All of these fine, little details matter when summed. More Science behind the Sound.

 

[Quattro Pete]

Originally Posted By: sleddriver
I'm trying to think of the name of the Rush song...."about the function and the form. Everybody needs to deviate from the norm." Could it be called Mixed Feelings perhaps?

Vital Signs?

 

[OVERKILL]

Your setup sounds incredibly detailed. Do you have kids? I would LOVE to experiment in the manner in which you've done, I just absolutely dread trying to do it with two dogs and three young children flying about and potentially screwing everything up. If you have similar obstacles and still managed this, it gives me hope, LOL!

Thank you for your detailed information on the stereo sub thing, that makes perfect sense. Previously, I had used a line-out feed for the sub and used a passive filter between the receiver and the amp for the sub. This was a stereo feed that I then turned into mono, as the sub was a single unit. The Denon also has the ability to give full range line-out while operating in a variety of amp modes feeding the directly connected drivers, but I don't believe so on the sub channel (could be wrong on that). It is very configurable via a web UI.

What are your thoughts on stereo subs with two separate single rather than two sets of dual drivers? You've noted you are using dual 12's, is this for increased presence or did you feel it was necessary for the stereo setup to work properly?

Do you run a centre channel? If so, what style?

 

[OVERKILL]

Originally Posted By: Quattro Pete
Originally Posted By: sleddriver
I'm trying to think of the name of the Rush song...."about the function and the form. Everybody needs to deviate from the norm." Could it be called Mixed Feelings perhaps?

Vital Signs?


Yup, that's what Google yields

 

[sleddriver]

Originally Posted By: Quattro Pete
Originally Posted By: sleddriver
I'm trying to think of the name of the Rush song...."about the function and the form. Everybody needs to deviate from the norm." Could it be called Mixed Feelings perhaps?

Vital Signs?
Yep, that's it. Just checked the lyric sheet.

 

[KitaCam]

Klipsch KSW-10 10-Inch 225-Watt, a thriftshop find.

 

[sleddriver]

No kids here. Never married. To kid proof, you always use sturdy spkr grilles like 1/4" hardware "cloth" covered in fabric. "Out of sight, out of mind". Kids love to touch/poke/push on bare tweeter domes so they need to be hidden from view. You can also build an entertainment center to hold your loudspeakers as well. It does affect the sound, but they're now enclosed and up higher and behind grilles.

As they get older, you can involve them in listening tests, play different types of music, play sine waves and have them guess the freq, etc. Make it fun and involving. You'll be training their listening skills and they'll just be having fun. IOW, they won't know they're actually learning something!

Re: Dual drivers. I didn't design these bass cabinets. They were designed by Joe D'Appolito. His rationalle was to double up on drivers as more cone area was needed to truly reproduce the lowest octaves of organ music with authority. He and Bock tested many single drivers, some quite expensive. They found a single driver was either throw or power limited. They also preferred a sealed alignment first, but quickly discovered it wouldn't meet their goals. They also downsized the box volume from optimum to increase the SA factor. To compensate, they increased the gain of the EQ filter. IOW, lots of choices to be made and factors to consider, as in any design.

Point is you don't need dual drivers for stereo subs. Singles will work fine. However, a single driver will have to work harder than two in order to move as much air. Higher excursions can cause increased THD. This is what D'Appolito ran into.

Thor only uses a single driver, but Linkwitz' custom EQ and the quality of the driver used, make all the difference. A pair of Thors + a suitable amp would make an excellent bass system for any system.

Short also used a single driver, but with a passive radiator in his subwoofer design. I think it was a Peerless. The PR is more efficient than a port and has a larger radiating surface. You can read up on his thinking over at North Creek Music's site.

I do run a center channel, custom built. It's currently not active because surround sound is still off-line. I need to reassemble the Parasound multi-channel amp after recapping the main PS, then install in the entertainment center, hook it up, set the surrounds in place, then measure and adjust levels to "dial it in". Just been too busy of late.

I did a huge amount of work on the sled this year. It's documented over on MVS. It was one thing after another after another....very stressful actually as it was all unrelenting for nearly 9 months.

I also still need to put the covers back on my old Tek oscilloscope. It went Tango Uniform while using it to troubleshoot another project. It's a mil-spec scope built for the USAF and worth keeping going. But I'd never fixed something as complicated as it before.

I need a vacation from my life to recoup!

North Creek Thunder: http://northcreekmusic.com/Retired/Thunder_Subwoofer/thunder_subwoofer.html

Linkwitz Labs Thor: http://www.linkwitzlab.com/thor-intro.htm

 

[OVERKILL]

Thanks for the links!

No worries on the kids poking stuff at this point, the youngest is 8. However getting them into it has been a bit more challenging and kids generally lack patience.

 

[sleddriver]

Your Welcome!

Play them soundtracks of birds, the ocean, etc. recorded in the wild. Your dogs will enjoy that too. My cats used to get mighty curious and start looking for birds! Staring at a speaker and meowing! Pretty funny. The audio laser trick.

You can also record their voices and play it back so they can hear themselves. Family get-togethers, birthdays, holidays, are all good to do. Bedtime stories too. Backed up and archived, they'll have these forever.