Too loose bass on Quest Z Speakers

[Yoss_UK]

Hi I'm a newbie to this forum.

I am the proud UK owner of a pair of Quest Z speakers, serial number QEEH401Z. I bought them from another user a couple of years back.

In most respects I believe they provide one of the most authentic and musical sounds imaginable. In particular I find their reproduction of the solo female voice simply amazing.

However, I do have one problem with them. I find their bass response very "loose". They have a contour switch that reduces -3db from 60 to 150Hz. However, setting this on renders bass a bit life-less, while leaving it unset leaves the bass very loose, boomy and imprecise.

I have installed power cleaning devices to the wall sockets to see if this would help and they do, but only a bit.

I have also tried setting the contour switch on and adding a REL Stentor II sub-woofer to the system. However, this seems to complicate matters further and I'm not sure then that all three speaker systems, ML electrostatic, ML bass unit and REL achieve the right cut-overs.

Is this bass problem typical with Quest Z speakers ? If so is there a cure or an upgrade that I can buy ?

Yours hopefully

[kwr]

Hi,

Two thoughts straight up.

What size is your room and how far are the speakers off the walls?

What power amplification are you using?

Kevin

[JonFo]

I had a similar issue with my Monoliths a few years ago. The first fix is to update the woofer. Your QuestZ is now 13 years old, and due for a woofer upgrade.

It's very simple to do physically. The challenge is finding the right driver.

Physically, it's a pretty standard 12" form factor, so lots of choices on that front. In terms of T/S parameters, it's probably pretty similar to the Monoliths, but I'm not sure. Anyone know what the driver parameters were for the QuestZ?

It would be interesting to discuss the options for drivers to perform this update with. The model I used in my Monolith woofer upgrade are no longer made, nor would I say, recommended.

Given you have a subwoofer, you really need the bass driver to cover the roughly 60Hz to 150Hz range. Which really means you need a good 12" driver that’s clean and flat out to 500Hz (considering the crossover slopes in the stock QuestZ).

There are not a whole lot of 12" that are that clean and smooth into the mid-bass. Most try to be sub driver candidates, and you do not want those.

So any recommendations out there?

[attyonline]

Before you start swapping out drivers, I would take a hard look at room acoustics and placement options. The driver is obviously in good shape or it would sound horrible. You do not need a new woofer. Moving the speakers and listening can be tedious, but that is the first step. Slight movements of a few inches can make a big difference. Bass traps or other bass room treatments are usually what does the most to aleviate bass problems, but they only work optimally when you have your speakers in the best position in your room. Good luck.

[JonFo]

Before you start swapping out drivers, I would take a hard look at room acoustics and placement options. The driver is obviously in good shape or it would sound horrible. You do not need a new woofer....

Making sure it’s not a room issue is indeed the first thing to check, however, if the driver is the same Eminence used in the Monolith's, then it is suspect at the very least due to age alone.
My dedicated room was designed around my Monoliths (and other ML’s), and I spent months tweaking placement, crossovers, etc. and finally realized that it was the darn drivers.
And no, it doesn’t have to sound horrible to be in need of replacement. What happens is the compliance of the surround changes over time and affects the distortion characteristics. Not to the point of where you would immediately notice, but significant enough to be bothersome.
The real proof is that as soon as you update the driver, the ‘tightening’ of the bass and mid-bass is so noticeable, you wonder why it was not obvious before that’s where the problem was.

Of course, room issues typically cause most FR and quality issues, and those in turn can mask an issue with a driver. But as noted, a 13 year old 12” driver should at least be inspected and validated.

Here’s one way to help validate:
Disconnect the jumpers to the panels on the binding posts and power only the bass sections of the Quest, use music and test tones to evaluate positioning and potential driver issues.
Steady test tones in the 80 to 140Hz will clearly reveal issues with a weak compliance in a woofer, and will be noticeable in ‘flabby’ (I.e. lot’s of harmonics) mid-bass.

Also, driver technology has moved forward a good bit in the past 15 years, and some of the better units out there are substantially superior to what was available in the late 80’s. The challenge is to find a good match for the exiting enclosure and crossover. Doing your own active crossover eliminates that variable and gives you more control. Although I agree, that’s not an option many of you would pursue.

[robertawillisjr]

An inexpensive aid might be to put 50lb lead shot bags on the woofer. This usually helps in terms of speed and response. The bags are ugly, so I use a good black fabric to cover them. You might try looking in the tweaks thread (which I haven't done...Sorry)

I would be interested in looking into improving the woofer. The last time I spoke with someone at ML it was strongly NOT recommended. Ditto for electronics. I have often thought that an upgrade in woofer and electronics would be interesting (depending on price). Recently, I have wondered about the possibility of using the new 'stat material for older panels.

[Yoss_UK]

Hi,

Two thoughts straight up.

What size is your room and how far are the speakers off the walls?

What power amplification are you using?

Kevin

Hi KWR, my room is 5m by 4m. The speakers are at the narrow end of the room. I don't have much space, so the rear of the speakers are about 6" off the wall. I drive them with a Chord 1200B power amplifier. It puts out 250W rms per channel. Thanks for your help.

[Yoss_UK]

Making sure it’s not a room issue is indeed the first thing to check, however, if the driver is the same Eminence used in the Monolith's, then it is suspect at the very least due to age alone.
My dedicated room was designed around my Monoliths (and other ML’s), and I spent months tweaking placement, crossovers, etc. and finally realized that it was the darn drivers.
And no, it doesn’t have to sound horrible to be in need of replacement. What happens is the compliance of the surround changes over time and affects the distortion characteristics. Not to the point of where you would immediately notice, but significant enough to be bothersome.
The real proof is that as soon as you update the driver, the ‘tightening’ of the bass and mid-bass is so noticeable, you wonder why it was not obvious before that’s where the problem was.

Of course, room issues typically cause most FR and quality issues, and those in turn can mask an issue with a driver. But as noted, a 13 year old 12” driver should at least be inspected and validated.

Here’s one way to help validate:
Disconnect the jumpers to the panels on the binding posts and power only the bass sections of the Quest, use music and test tones to evaluate positioning and potential driver issues.
Steady test tones in the 80 to 140Hz will clearly reveal issues with a weak compliance in a woofer, and will be noticeable in ‘flabby’ (I.e. lot’s of harmonics) mid-bass.

Also, driver technology has moved forward a good bit in the past 15 years, and some of the better units out there are substantially superior to what was available in the late 80’s. The challenge is to find a good match for the exiting enclosure and crossover. Doing your own active crossover eliminates that variable and gives you more control. Although I agree, that’s not an option many of you would pursue.

Thanks for taking the time out to give me such a comprehensive reply, Jonathan. I carried out the test you suggested. I run the Quest woofers on a separate channel (Chord 1200B power amp) to the Quest's electrostatic speakers, so it was just a question of turning off the woofer channel.

The woofer section of the Quests, when driven on their own, sound really vacuous and loose, there's certainly no sense of tightness or punch to them.

In view of your remarks I am giving serious consideration to seeing if I can get a UK dealer to do me a part-exchange on the Quests for a new pair of ML's. What is the best/current version of the Quest Z ?

Again, thanks very much for your help, much appreciated.

Best regards

Alan

[kwr]

Hi KWR, my room is 5m by 4m. The speakers are at the narrow end of the room. I don't have much space, so the rear of the speakers are about 6" off the wall. I drive them with a Chord 1200B power amplifier. It puts out 250W rms per channel. Thanks for your help.

That is very close to a wall. I realise you may be working with space constraints but you wil be getting a huge amount of bass reinforcement from the room.

Before you start changing speakers/drivers etc pull the speakers at least 1m into the room. Sit with your head at least 1m off the wall behind your listening position (same bass reinforcement issue). This should improve your sound hugely. If this works consider putting the speakers on castors so you can shift them out easily for listening sessions.

Best of luck. I strongly suspect that you are dealing with speaker positioning problems. Could you post some pictures of your room? We can then tailor suggestions to your room.

Kevin

[Yoss_UK]

Hi Kevin

I have tried to attach some pics of my room to this message using "Manage Attachments", but even though I have reduced the pics down to 66KB, I am getting an error message when I try to upload the first of them.

Am I missing something here ? Sorry to be a nuisance.

Meanwhile re the speaker problem itself, I am seriously thinking about selling the Quests off. If the problem is the size of the room, which I guess it might just be, there's not much I can do about that.

Thanks again for the advice.

Best regards

Alan

[kwr]

Meanwhile re the speaker problem itself, I am seriously thinking about selling the Quests off. If the problem is the size of the room, which I guess it might just be, there's not much I can do about that.

I have had Monoliths working well in a room a bit smaller than yours but positioned well into room. You are going to get wall bass reinforcement with any speaker close to a wall.

Often if you are obliged to put speakers close to the wall a stand mount monitor type speaker potentially supplemented with a sub can be a good solution. Audionote and Linn make speakers balanced to sit against a wall.

Have you had a chance to pull the speakers into the room?

Kevin