Am I getting full range of floor standers when sub is off?

Hi, I have a kef psw2000 sub. I have my amp going to the sub first via speaker cables and then out from the sub to my mission 752 speakers. There is an active filter on the outputs of the sub. My question is, when the sub is turned off, will the active filter still be working or will I be hearing the full dynamic range of the speakers until the sub is powered up? Thanks

 

When the sub's power is off, which means your active filters are also turned off, your Mission speakers will receive the full range directly from your amp, with no interference from the subwoofer.

 

That is incorrect on this subwoofer. The subwoofer incorporates a passive filter for the main speakers (a 300uF capacitor, providing a 130Hz filter at 4 ohms or 65Hz with 8 ohm speakers), which is still in place when the subwoofer is off or unpowered.

 

I used to have my mains and sub hooked up in the exact way the OP does. With the sub OFF, no signal went to the mains, so maybe reading the manual or contacting tech support will clear his doubts ? Plus, the internal filters cutoff is usually very high, so he really should be able to tell by ear.

 

I just read the manual online and the active filter cuts at 160 hz; insanely high and localizable, unless the frequency cutoff adjustment knob acts over the internal filter, which is not usually the case, and the manual doesn't mention it.

 

There doesn’t sound like there is any difference to the missions when sub is on or off. I think I will go back to having the speakers and sub wired independently from the amp so that I get the full mission 752 experience. Doesn’t seem right using them with half the bass cut.

Thanks for all replies

 

My current approach exactly.

 

Depends on how you have it wired. If the speaker wires go into the sub and then the speakers the filter will not be defeated. If the sub is driven directly by the amp and connected to nothing else the filter will be off.

 

Yep, have been listening to the former for a couple months now and had begun to get irritated by the ultra crisp sound. Now wired to the latter and sounds a lot fuller.

 

Sorry, I seemed to have answered incorrectly from my assumptions that your subwoofer should operate as I personally think any good active subwoofer should, and that you were correct that the internal crossover is active.

 

Yeah! If you had a GOOD subwoofer this wouldn't happen.

Sometimes people should reread what they type and think if it may seem off-putting to others.

 

I don't see any reason to buy full range speakers and then cut out the bass from them?

But that's just me.

As an alternative to wiring the sub independently, you could have the cables going directly to the speaker first, then from the speaker to the sub.

I personally don't like doing it that way either.

I would rather send a line level signal from the preamp out to the sub.

But, I like to send it into a device to digitize the signal, so that I can set the crossover frequency and slope, before it goes to the sub.

You have much more precise control that way, instead of using the plate amp in the sub.

 

@harby is correct, according to the schematic, the high level input (connected from the amp speaker terminals) has a 300uf cap in series for a fixed high pass to the main speakers. The line level inputs pass through a pre-amp stage, also fixed at about 130 Hz. The controls on the sub do not affect the high pass (bass cut) to the main speakers. This matters not if the sub is off or on, when connected to the amp speaker terminals, but at line level, the unit must be "on".

Also there was a revision on this model. The later version has an improved crossover circuit, which may provide variable high pass to the main speakers.

Now, despite the above info, the frequency response of this sub has its -3dB point at apprx 35Hz. Most floor standing speakers should go down to 45Hz or so, some of them a bit lower. (at the -3dB point) Most subs are not subs... they are glorified woofers that simply make more bass. More bass, often translates into poor quality bass. A sub when used with full range floor standers, should extend down to 25 Hz or even 20 Hz. Now we are in the sub range. Most music contains little to no energy below 40 Hz, So, a true sub should make no difference when connected, provided the main speakers have a frequency range down to about 40 Hz.

When the bass content of a music program DOES extend below 40 Hz or so, then you'll know it... the windows rattle, the floor vibrates, and without muddying up the bass. The bottom line, most subs in a good full range system should cross low, and should be "off" (not producing signal) most of the time.

 

And a LOT of recordings have weakly mixed-in lower bass, which the sub can amplify. I'm talking the first 2 octaves. My floorstanders get down to 39hz +/-3 db. Well recorded music kick major butt without the sub. With weak recordings, I just press speakers B on the receiver and the missing bottom end leaps to life. In this way, I do not use the sub for just the negligible extension from 39 to 25 hz it can provide. As you said, there's very little extension below 40 hz for practical purposes.

 

Closest my amp will do to a line level out is the headphone socket

 

A double bass or a 4-string electric bass guitar will both love their bottom note, which is an open "E" string at just over 41-Hz. So, it is mostly true that both acoustic and their electric representations, won't be playing below 40-Hz.

Noting that there are instruments that do play lower than 40-Hz. The low "C" on a piano is just below 33-Hz., A 5-string bass goes down to 30.8-Hz. A contrabassoon can dip down to 29-cycles. A pipe organ can play down to 16-Hz., but it takes a 32' pipe to get that low (and they have even larger pipes), so I wouldn't worry much about this.

A lot of bands have electronic keyboards and synthesizer's that do play in the low 30-Hz., range and below.

So, if we go with your observation that (which I am in agreement with) "Most floor standing speakers should go down to 45Hz or so, some of them a bit lower.", then subs that can play down into the 30's, are in fact subs, not woofers. A sub should not be evaluated by its -3 dB point as that is just a "measurement". Just because a sub has a measured -3 dB frequency spec in the high 30's does not preclude it playing far lower and with authority!

My front mains are Polk Audio LSiM707's, here is a little bit about them.

This is a Manufacturer's photo of the Polk Audio LSiM707 4-way speaker. It weighs 99-lbs. and its -3 dB point is 38-Hz. But, it will play down to 20-cycles.



This is physically a large speaker and can pressurize a large room with bass. Here is a cutaway view.

Even big speakers can benefit from having a sub in the system, for "weak recordings".

But I note, that there is a lot of information present in the 30-Hz. range that warrants having a sub in most stereo system's.

If you have mains already in your system that play down into the low 30's and perhaps down into the 20's, then you are excused from this conversation.

Now here is a 15" passive, commercial horn loaded sub. its -3 Db point is only 37-Hz., but that figure only represents its -3 dB point and it can play far lower and at a constant SPL of 133 dB's of continuous program material.

Despite having large front mains that can produce both deep bass and sub-bass, the system does benefit from having this large sub on the system, which is powered by a 1,600-Watt Crown amplifier.



The Fringe makes an important point here, "The bottom line, most subs in a good full range system should cross low, and should be "off" (not producing signal) most of the time".

While I don't know about this "most of the time" stuff. I would amend this statement to read, "The bottom line, most subs in a good full range system should cross low, and should be "silent" (not producing signal) when it is not needed.

I electronically cross over the UCS-1 at 40-Hz., so that the sub in only active at frequencies of 40-Hz. and below.

When it is not needed, then it is not there. When it is needed, then it is present, but transparent.

If we are playing some Dubstep, with deep, window rattling bass, then it is there "in spades". It is still largely transparent, because sounds at these frequencies can not be localized.

I run it through the processor and out the SFX channel with bass management, so the sub can be equally for HT and stereo. For stereo, I just send in a full range signal from the preamp to a unused channel of the HT processor.

In the HT mode, when you see the earth cracking open on the screen, you feel the experience of earth cracking open in the room. When the earth is done cracking open, then the sub is silent once again.

This is how to properly integrate a sub and to illustrate that with both large floor stander's and large three-way theater speakers, a sub is a useful welcome addition.

 

That is really odd. The line level out will not be on a power amplifier. but I have never owned a separate preamp (duh) or integrated which does not have a preamp out?

While they are both line level signal outputs, there is a practical difference between a strain "line out" and a "preamp out".

A line level out is not controlled by the volume control on the preamp or integrated, it is designed to go into another piece of equipment, such as a recording device, where you control the volume level within that device.

For a sub, you should always use a "preamp out" (if available) for a sub, because as you raise and lower the volume on the main system, the volume level on the sub will be raised or lowered accordingly. You still use the "volume" level on the sub to adjust the overall volume of the sub, relative to the system volume.

If you don't have some sort of "preamp out" available on your system, by all means, use your speaker level signal to drive the sub, either before or after the speakers, whichever your preference might be. That's why speaker level inputs are put on subs in the first place. Many choose to set up their subs this way. There is nothing incorrect in doing it that way. Which every way you can and how ever your preferences might be.

 

Dear @SandAndGlass : I'm aware of all you said, only I chose the path of setting up my sub to reinforce my many weak recordings instead of merely concentrating on frquency extension, because it works better for me and the music I listen to. Now if I had YOUR gear.........

 

No, I understand. As I commented, there is nothing wrong with powering it with the speaker level connections.

I have the sub powered by a Crown commercial amp in a rack behind the TV. I have a few of those RF remote AC on/off switches that I use to power the components that are behind the TV. when I don't want the sub on at all, I keep the on/off remotes on a table behind where I sit and just turn it off, like late at night.

Over the years I have made so many changes to the system and having it set up the way I have now works so much better for me, both sound and convenience wise. Doing it with speaker wire would be a nightmare!

Besides, my set up is different than those who are using a receiver or AV receiver for their source selection and amplification. I am using components and large and varied power amps, that are both tube and SS.

Since I have both stereo and HT applications to consider with the UCS-1, and my HT system is processor based. The sub must perform for dual use. Fortunately I cam up with the idea to take a signal from the preamp out of the integrated and run it into an unused channel of the processor, that way I can use the bass management features and the processor has no power amplification and therefore no speaker level outs.

The processor is designed to connect a sub via the line level RCA output from the LFE .1 channel. The processor also has a balanced sub out, because some users require a longer run to a powered sub, that might be placed away from the main system and by the speakers. This would be used to minimize any interference.

I use the balanced connection to go from the processor to the Crown XTI-2000, which powers the passive UCS-1 commercial sub.

The Crown is running in bridged mono mode, so a pair of speaker wires are connected to the two red speaker terminals in the center.

They are connected at the sub with a 1/4" phone plug. I could also use the commercial Nutrik Speakon type connectors to go from the Crown to the Speakon connector on the sub.


So I have to do it differently than either s speaker level or line level connection of an active home sub.

I do have a Polk Audio DSW PRO 660 that I use with the rears, but it is connected wirelessly. It's -3 dB limit is 25-Hz.

So I don't really use either of the home sub connection methods at present.

I think that you have actually come up with the better solution than running a wire to the Sub and then to the speaker or vice versa.

Using your "B" set of speakers is a far better idea of connecting the sub. That way there is no interaction between your sub and your mains and you can turn your "B" speakers on and off anytime you want to take your sub in and out of your system.



(Only someone like me would come up with all of this "crazy" stuff!)

 

I run the B set in a different room so not an option for me

 

That's fine. @The Pinhead, just came up with this solution because he wants to be able to take his sub in and out of his system by pushing a button, which I think is an interesting and clever idea.

Go right ahead and connect you sub via your speakers cables, it will work fine.

These things are not necessarily better or worse ways, as they are different alternate options. Different ways may suit different installations better than the other, for entirely different reasons.

Because I became accidentally aware of this, with an inexpensive stereo receiver that I used to run my rear speakers, I looked up your Arcam Alpha 3 handbook/manual.

It informs us that, with both channels driven, you amplifier is rated at 40-WPC into an 8-Ohm load. and with one channel driven it can deliver 50-Watts (typical) into the same 8-Ohm load or 80-Watts (typical) into a 4-Ohm load.

Basically, what this is telling us, is that you amplifier is designed to drive only one pair of 8-Ohm speakers at one time.

Inside of your box, you amplifier has two wires connecting each set of speaker switches in parallel. One switch can be on or the other switch can be on or they both can be on at the same time, being that they are wired in parallel.

If you take two 8-Ohm loads and you connect them together at the same time the two pair of speakers are now presenting a 4-Ohm load on the amplifier. Which is the same as your amplifier running one set of 4-Ohm speakers, which you amplifier doesn't seem to indicate that it is OK to do.

Now I may be looking at the incorrect information for you amplifier, so you may want to check the source that I have used, which is an online library of manuals. Here is the link to the page for the Arcam Integrated Amplifier Alpha 3 Handbook, page 6 of 9.

Most speakers are typically 8-Ohm speakers. So it is OK two run one set or the other set, but it is not recommended that you run them both at the same time, unless you are running them at lower volume levels. It is also good to check both pairs of your speakers to verify that either set are 8-Oms speakers and that neither are 4-Ohm speakers.

When you move from an 8-Ohm load to a 4-Ohm load, Ohm's Law states that twice the amount of current will be flowing (if it can).

From what I am reading in your amplifier's specs is that you can only connect a single 4-Ohm speaker to you amplifier at any given time.

This does NOT effect you hooking up your sub from the speaker level input's. The input impedance on the sub is very high as to not place a noticeable load on you amplifier.

F.Y.I.

 

That works for me!
The Polk Audio LSiM707 4-way speaker appears to be well engineered, a fine full range speaker. The cut off point will vary according to the woofer alignment in the cabinet, a sealed enclosure vs ported vs transmission line vs open baffle, and also other variables. Most subs are powered, so the woofer has "help" from an eq curve designed in the amplifier, and gobs of power needed to extend into the sub range. Of course our placement near floor and room boundaries assist in acoustic amplification of bass frequencies!

 

The 707's are built amazingly well. The driver's are excellent. the cabinets and their finish, you would not even remotely suspect that they are Polk's. And I love Polk speakers. These retail for $4k/pr. and it is only because of Polk's size that economic's of scale allow them to be built and sold for these prices. I have read professional reviews where they have been compared to $6k - $8k speakers.

Even that much better, I bought these on a Polk 50% off sale, so I got them for $1,000 each! This is one of the best deals in the audio world as far as new speakers are concerned. Now, myself, I am a total convert to tubes. But, I don't think that tubes really bring that much magic to modern day tower speakers which have complex crossovers and are around 90 dB efficient and are designed to work with powerful SS amplifier's.

I am driving the 707's with an Emotiva 250-Watt (into 8-Ohms) SS 72-lb. XPA-2 (Gen I) power amplifier that I bought on sale back in 2012 for $690. The amplifier can deliver 400-watts into 4-Ohms, so it is designed to deliver a lot of current and has a huge power supply (the 707's are 8-Ohms)!

Together these are amazing, I would not change either one of them for anything! The both of them together do what ever they are needed to do.

The UCS-1 sub is horn loaded so it is natural sounding and is around 100 dB efficient. The sub points out into the room at the teal sofa for maximum effect and that minimizes LF sound from exiting through the rear of my office.

Of course, I still have a sub with a pair of 18" driver's in the back of my mind. I just need to figure out how to implement it in the room.

The volume level of the UCS-1 is connected to the volume level of the 707's. I can adjust that more or less with the processor's volume level via the processor's.

 

Sorry, I need to update my profile there. I now have a Marantz pm6006 uk edition.