REVERSING SUBWOOFER CONNECTION: AMP SPEAKER OUT to MAIN SPEAKERS then to SUBWOOFER

[Gary.D.Olson]

First, the exciting announcement: I just upgraded from vintage Canton Karat 920 DC bookshelf's (bought new in 1996) to Canton CT-800's (just acquired via craigslist for $250). These are small 3-way floor standers with a 10" woofer. On to the question.

 

I've been told in this forum that anyone who passes audio signal through a subwoofer's crossover - whether line-level OR speaker-level - and then on to their main speakers is feeding a degraded signal to their main speakers - even when using quality cables.

 

Is there any reason one shouldn't connect their speaker cable directly to the main speakers FIRST and then on to the subwoofer? I understand the speakers and amplifier wouldn't benefit from the crossover in this configuration, but that seems a better compromise over the ghastly degradation of sound quality so many write about.

 

If that is okay, is it also okay to do this to just one channel, or would doing so create an imbalance between the left and right main speakers???? (this is yet another reason I hate having to use a sub)

 

Much obliged.

 

 

Gary

[jcn3]

Subs are designed with a very high impedance to support being in parallel with your speakers. Technically, parallel is parallel so it seems like it should be okay. What sub are you using? Does it actually have a high pass filter for the mains?

 

Whatever you do, do the same for both channels.

 

 

No sub-out line level signal from your pre-amp, huh? That's by far the best way to do it . .

[Gary.D.Olson]

Subs are designed with a very high impedance to support being in parallel with your speakers. Technically, parallel is parallel so it seems like it should be okay. What sub are you using? Does it actually have a high pass filter for the mains?

 

Whatever you do, do the same for both channels.

 

 

No sub-out line level signal from your pre-amp, huh? That's by far the best way to do it . .

 

The sub is a Velodyne F1200. It has a built-in active crossover but using it means I have to send the signal through something that will degrade SQ, according to many here. That's the issue of this thread. No sub out either though that would've solved the problem.

 

Thanks.

 

 

 

Gary

[wgscott]

What you describe should be fine and in fact is how some manufacturers recommend it be done even if you have the other option.

 

However, if it is not too much trouble, you should try it with the velodyne crossover and hear for yourself whether it is better, worse or the same. Always be wary of dogma.

[mayhem13]

Hi Gary. This would all depend on 'how' your Velodyne creates the high pass filter built in for your mains speakers. 'Most' subwoofer amplifiers use a is simple, single capacitor which unfortunately creates a huge freq spike in your mains speakers just above the crossover knee....or around 100hz. In some cases, this spike or mode works to counter nulls induced by the room. In other cases, the effect is a pronounced, boomy sound.

 

You'd have to be the judges here as each room is different.

[Gary.D.Olson]

First, the exciting announcement: I just upgraded from vintage Canton Karat 920 DC bookshelf's (bought new in 1996) to Canton CT-800's (just acquired via craigslist for $250). These are small 3-way floor standers with a 10" woofer. On to the question.

 

I've been told in this forum that anyone who passes audio signal through a subwoofer's crossover - whether line-level OR speaker-level - and then on to their main speakers is feeding a degraded signal to their main speakers - even when using quality cables.

 

Is there any reason one shouldn't connect their speaker cable directly to the main speakers FIRST and then on to the subwoofer? I understand the speakers and amplifier wouldn't benefit from the crossover in this configuration, but that seems a better compromise over the ghastly degradation of sound quality so many write about.

 

If that is okay, is it also okay to do this to just one channel, or would doing so create an imbalance between the left and right main speakers???? (this is yet another reason I hate having to use a sub)

 

Much obliged.

 

 

Gary

 

 

CORRECTION!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

 

I just re-read the Velodyne manual and found the hi pass filter is actually "passive". Only the "low" pass filter is active. Full specifications are as follows:

 

 

Amplifier: 100 Watts RMS Class A/B

Driver: 12" with 9/16th" Linear Travel

Voice Coil: 2 3/8" Diameter

Magnet: 56 oz

Cone: Resin/Fiber

High Pass: Passive 85 Hz - 6 dB Slope

Low Pass: Active Adj. 40-100 Hz

Freq Resp: 20-85 Hz (+/- 3dB)

Distortion: Less Than 1% (25 Hz @ 104 dB)

Cabinet: 16 5/8" Cube

Finish: Black Vinyl Woodgrain/Granite Vinyl Base

Weight: 55 Lbs.

[Gary.D.Olson]

Subs are designed with a very high impedance to support being in parallel with your speakers. Technically, parallel is parallel so it seems like it should be okay. What sub are you using? Does it actually have a high pass filter for the mains?

 

Whatever you do, do the same for both channels.

 

 

No sub-out line level signal from your pre-amp, huh? That's by far the best way to do it . .

 

I would have another problem if I'm forced to use both F1200 subs: There's no room for a sub on the right side. Possible solution: place both of them directly UNDER the main speakers.

 

To get the tweeters (19.5 high) at seated ear level (40" high), my mains would need to be raised appx 20.5". Sitting them directly on top of the 16 5/8" high subs would place the tweeters 3" below ear level. If placing them directly on the subs creates magnetic and/or vibration issues, I could build custom stands to lift them off the subs and line the bottom of the speaker shelf with metal, if necessary.

 

Any thoughts?

[bdiament]

Hi Gary,

 

I would have another problem if I'm forced to use both F1200 subs: There's no room for a sub on the right side. Possible solution: place both of them directly UNDER the main speakers.

 

To get the tweeters (19.5 high) at seated ear level (40" high), my mains would need to be raised appx 20.5". Sitting them directly on top of the 16 5/8" high subs would place the tweeters 3" below ear level. If placing them directly on the subs creates magnetic and/or vibration issues, I could build custom stands to lift them off the subs and line the bottom of the speaker shelf with metal, if necessary.

 

Any thoughts?

 

I have found great benefit in isolating my speakers from vibrations. I shudder at the idea of placing them atop subs-- basically putting them on "shake tables". (I isolate my subs too.)

 

I suggest trying it yourself, both ways. Listen to a good recording and check for things like spatial resolution and dynamic "attack", both of which I find compromised when vibrations can easily enter the speaker (or its crossover).

 

Hope this helps.

 

Best regards,

Barry

Soundkeeper Recordings

Barry Diament Audio

[mayhem13]

Hi Gary,

 

 

 

I have found great benefit in isolating my speakers from vibrations. I shudder at the idea of placing them atop subs-- basically putting them on "shake tables". (I isolate my subs too.)

 

I suggest trying it yourself, both ways. Listen to a good recording and check for things like spatial resolution and dynamic "attack", both of which I find compromised when vibrations can easily enter the speaker (or its crossover).

 

Hope this helps.

 

Best regards,

Barry

Soundkeeper Recordings

Barry Diament Audio

 

if the sub enclosures resonate that badly, they shouldn't be in a high end system anyways.......but if they did, you'd be hard pressed in an AB listening test to pick out which is decoupled.....IME of course. Most commercial mains cabinets have quite a few resonant modes that are far more impactful than those created by a sub enclosure's walls.

[mayhem13]

CORRECTION!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

 

I just re-read the Velodyne manual and found the hi pass filter is actually "passive". Only the "low" pass filter is active. Full specifications are as follows:

 

 

Amplifier: 100 Watts RMS Class A/B

Driver: 12" with 9/16th" Linear Travel

Voice Coil: 2 3/8" Diameter

Magnet: 56 oz

Cone: Resin/Fiber

High Pass: Passive 85 Hz - 6 dB Slope

Low Pass: Active Adj. 40-100 Hz

Freq Resp: 20-85 Hz (+/- 3dB)

Distortion: Less Than 1% (25 Hz @ 104 dB)

Cabinet: 16 5/8" Cube

Finish: Black Vinyl Woodgrain/Granite Vinyl Base

Weight: 55 Lbs.

 

So as it's passive and only 1st order, it is the simple single capacitor type.....so in other words, don't use it. You can instead parallel your mains from the subs speaker level inputs instead. Mind you this offers no protection to your mains from low freq content, but if you're not talking high volumes, the natural rolloff of your mains will blend much better that a poor 1st, second or 3rd order passive HP filter any day of the week.

 

You'll need to get some kind of an idea of what your mains speakers in room F3 is in order to get a good starting point for where to cross your subs. F3 is the point where the system is down or -3db from flat. Most specs are anechoic where the actual in room is lower in freq due to cabin/boundary gains.

[bdiament]

mayhem,

 

if the sub enclosures resonate that badly, they shouldn't be in a high end system anyways.......but if they did, you'd be hard pressed in an AB listening test to pick out which is decoupled.....IME of course. Most commercial mains cabinets have quite a few resonant modes that are far more impactful than those created by a sub enclosure's walls.

 

!?!

 

Who said anything about resonating enclosures?

The only thing I'm "hard pressed" about is figuring out what your statement has to do with the post you cited.

 

Best regards,

Barry

Soundkeeper Recordings

Barry Diament Audio

[Gary.D.Olson]

So as it's passive and only 1st order, it is the simple single capacitor type.....so in other words, don't use it. You can instead parallel your mains from the subs speaker level inputs instead. Mind you this offers no protection to your mains from low freq content, but if you're not talking high volumes, the natural rolloff of your mains will blend much better that a poor 1st, second or 3rd order passive HP filter any day of the week.

 

You'll need to get some kind of an idea of what your mains speakers in room F3 is in order to get a good starting point for where to cross your subs. F3 is the point where the system is down or -3db from flat. Most specs are anechoic where the actual in room is lower in freq due to cabin/boundary gains.

 

I'll take a listen with and without sitting directly on the sub to figure that one out.

 

Regarding crossover point: Canton's specs say 22-30,000 Hz but I doubt these speakers are -3dB at 22 Hz. Bass is pretty damn good without a sub but not THAT good. Any suggestions how to go about finding that point?

 

Thanks.

 

 

Gary

[Sam Lord]

I like Barry's ideas. My subs are beneath my mains, but they do not touch. I have very, very heavy, stout, and damped stands: Sound Anchor Adj2s. Subs are Velodyne DD12+s.

 

Also, I would never use the speaker-level terminals to derive a signal for *anything* if I could avoid it. Right now I run 3 wires from each pre output to my amps and subs, and thus use one amp channel per driver. This isn't ideal either, but at least the preamp outputs see an almost completely resistant and pretty stiff load. The ideal solution is a preamp with multiple buffered outputs. But those are, sadly, rare.

[bdiament]

Hi Sam,

 

I like Barry's ideas. My subs are beneath my mains, but they do not touch. I have very, very heavy, stout, and damped stands: Sound Anchor Adj2s. Subs are Velodyne DD12+s.

 

Also, I would never use the speaker-level terminals to derive a signal for *anything* if I could avoid it. Right now I run 3 wires from each pre output to my amps and subs, and thus use one amp channel per driver. This isn't ideal either, but at least the preamp outputs see an almost completely resistant and pretty stiff load. The ideal solution is a preamp with multiple buffered outputs. But those are, sadly, rare.

 

Agreed on the speaker-level terminals too. In the absence of separate buffered outputs for the subs at the preamp, I still prefer to take a preamp level signal to feed the subs directly (just as I feed the amps for the main pair directly).

 

Best regards,

Barry

Soundkeeper Recordings

Barry Diament Audio

[Gary.D.Olson]

Sound quality took a steep nosedive with the speakers sitting directly on the sub woofers - both with and without the subs switched on. And... whether seated or standing, these Canton's sounded better on the (carpeted) floor. Maybe this was how they were designed to be used, though I may try tilting them up slightly.

 

I also preferred the sound without the subs. "Placement" might improve that to some degree, but the Canton's bass seems more than adequate to my ears. I'm going to spend more time getting acquainted with these speakers before making any further changes.

 

Thank you all for your suggestions.

 

 

Gary

[maelob]

I have a Mac power amp and I run both my sub and mini Maggies speakers with 2 pairs of speaker wire from the same output with no issues. I am lucky my amp speaker connectors are big enough that let me connect both. I still can adjust the sub freq and the Maggies remaining full range.

[Sam Lord]

Sound quality took a steep nosedive with the speakers sitting directly on the sub woofers - both with and without the subs switched on. And... whether seated or standing, these Canton's sounded better on the (carpeted) floor. Maybe this was how they were designed to be used, though I may try tilting them up slightly...

 

...I also preferred the sound without the subs. "Placement" might improve that to some degree...

Gary

Hi Gary, You didn't ask for a long response, but I recall the name of a very sketchy skiing line in Jackson Hole: "Talk is Cheap."

 

Sooo.... Subs can make good bases if they are kept turned off, but wait.... Anyway the question is, "what can I do to minimize movement of my speaker enclosures?" If the sub is a 400 lb block of lead, then you're pretty safe. If it's under 100 lbs, not so much. Actually, a solution better than most kinds of spiking on typical floors is to allow your mains to glide on a horizontal plane, e.g. mounting on Aurios. This removes most of the horizontal spring action of the enclosure/spike/floor system. Using heavy, spiked platforms beneath and even on top of mains is very good.

 

Re tilting, that is part of the "placement" you mentioned. It is critical. Just how you tilt the speakers depends on their design, and speaker makers hate to provide useful information about this. If you have two-way speakers, you can get get nearly perfect phase coordination of the drivers by setting them at the correct attitude for precisely one listening position. The best test IME is a mono-recorded tom-tom thwack. If you test with both speakers running, be certain that you at your preferred listening position and are precisely centered on a line parallel to the L to R axis connecting the speakers. Adjust tilt up or down in small increments, usually up, until the thwack sounds most real. Our ears can detect phase errors between midranges and tweeters corresponding to around 5 microseconds, a phase shift of ~3 degrees at 2kHz, or about 1/16 of an inch. (Some folks say +-2 usec!) I think this is the most cost-effective tweak there is. Subs have some output into the hundreds of Hz, so you should stay within 1/2 inch of the time-coherent placement, perhaps using the same similar technique as above. A related error I made on this forum that happened a while back was to advise folks to place the sub drivers a couple inches closer to your ears than the midrange drivers. But this assumed a passive crossover on the sub. For a digital-crossover sub like the DD12, the sub defaults to no lag in its response, unlike a mains bass driver which lags because it is in series with an inductor or two. So a digitally-controlled active sub should be about even (equidistant from your ears) with the low driver of your mains, or even slightly farther back. It is interesting that one can argue for different interpretations of phase coordination between drivers, but IME *everyone* likes one arrangement of a given system best.

 

Finally (clap), I urge people to try another thing: zero toe-in. If your speakers are parallel to the walls in a rectangular room and you have them angled to point at your ears, try them without toe-in. To do this right you need to re-time-align them, but give it a try. There should be no advantage in the direct radiation from the speakers, rather a slight disadvantage, but Every system I've set up in such rooms has sounded better this way. Why? I suspect that the advantage comes from early echoes which are more time-coherent than those from toed-in speakers. Thinking about the side- and back-wall reflections will bear this out. I think the result is a more realistic soundstage, with the listening room disappearing more. Try it!

 

I have a Mac power amp and I run both my sub and mini Maggies speakers with 2 pairs of speaker wire from the same output with no issues. I am lucky my amp speaker connectors are big enough that let me connect both. I still can adjust the sub freq and the Maggies remaining full range.

Well I might eat my words and copy you if my current arrangement doesn't tweak better. Taking the sub signal from the mains speakers adds their distortion to the subs' signals, and adds noise from an extra amplification stage and attenuator. Still there are many happy REL sub owners out there, and subs are less resolving of noise problems than other drivers. My amp or sub inputs (both are Class D circuits) might be throwing out more noise on the grounds than is ideal. I'll know after testing that eliminates other variables. Cheers

[Sam Lord]

Well I might eat my words and copy you if my current arrangement doesn't tweak better.

Redacted. I just switched to Audirvana+ and most of the hash is gone. I'll still do more tests, but boy was that a cheap upgrade.

[Gary.D.Olson]

Sooo.... Subs can make good bases if they are kept turned off, but wait.... Anyway the question is, "what can I do to minimize movement of my speaker enclosures?"

 

There should be no advantage in the direct radiation from the speakers, rather a slight disadvantage, but Every system I've set up in such rooms has sounded better this way. Why? I suspect that the advantage comes from early echoes which are more time-coherent than those from toed-in speakers. Thinking about the side- and back-wall reflections will bear this out. I think the result is a more realistic soundstage, with the listening room disappearing more. Try it!

 

Sam,

 

Even if my subs weighed 1000 pounds and were never plugged in they wouldn't make good bases for these "particular" speakers. They just sound better (by a wide margin) sitting at floor level.

 

I like your ideas about reflections from non-toed-in speakers. John Bonham's drums sound fantastic to me for much the same reason. They put him in a live room and used ambient mic techniques. The result was a BIG sound that made the whole recording sound more like a live performance. I've always preferred the sound of music in rooms with mild to moderate ambient sound. Of course, you gotta start off with the right room. Many recording artists gladly travel thousands of miles for studios with great sounding rooms.

 

Thanks.

 

 

Gary