Uneven speaker response

[farflungstar]

Why might one speaker have a better low frequency response?

So for a long time I've noticed that my right ANe has been deficient in low bass, below about 40hz in comparison to the left. I've put it down to the room but yesterday I swapped them over and whilst the room makes a difference there is definately a difference in output between them. Why might this be? I'm loathe to open the offending speaker up as they are a nightmare (old style) - but could it be something as simple as placement of wadding?

[Lawrence001]

Or it could be something amiss in the crossover

Sent from my NEM-L51 using Tapatalk

[Bourney]

Could be a poor joint or a crossover component. I'm sure there used to be a variable resistor in there. Pretty easy to swap the bass drivers over to take them out of the equation. Remake the biwire link connections if you're single wiring.

[walpurgis]

It could be that one bass driver has a lower compliance to the other, due maybe to a unit having been replaced at some time and the physical spec being different. Do the bass/mid units look identical?

Also, there could be differences in the type or amount of internal damping material between the two speakers.

[Bourney]

My Es have a newer bass unit in one due to one getting damaged but I can tell no difference in output and imaging is stable (superb in fact). I have to say though, when I bought the driver, Audionote advised that you could experience differences with using different aged units.

[farflungstar]

The drivers look identical in every way including age. The variable resistor is for the tweeter.

Opening these up is a fking nightmare as they are fixed with blue tac (or similar) and it destroys the chipwood when prising the drivers out - would a bad solder joint really have this effect? Passing through everything above 40hz (guessing) but very very little below? I can imagine wadding might have that effect... I don't know what to do - having lived with them for a couple of years and intending to buy new speakers in October I don't know whether to leave well alone.

[hifinutt]

needs sorting otherwise you won`t be able to sell them ! are there no Spanish hi fi speaker repairers ?

[Bourney]

You can get the drivers out if you're careful and patient. Mine are older ones and there was No damage when I removed them.

[User211]

If you have a test mic press it into action and post the FR results?

Might provide further clues but will definitely show the extent of the problem if you know what you are doing. Best done with one speaker at a time in the same position without moving the test mic between samples.

[cooky]

A technique I adopt where a mastic/gasket has been used is to remove the screws/bolts, then using allen keys in the mount holes-get a mate to help, 4 is better than 2, prize the driver frame away from the cab. Take care not to bash the cone, use a circle of cardboard as protection.Dont bend the frame-it works best on cast frames like Tannoys.

[farflungstar]

Mastic and blutac are very different - blu tac goes very very tacky after a long time and is a b*tch when stuck to old crumbling chipwood. Someone opened then up before (to rewire with SPX cable) and did a crap job of getting the drivers out. I really don't want to go through it again after opening them up when I first got them to check them over. Bugger...

[spendorman]

Not a cure, but possibly a means to test them, connect one speaker out of phase, place them front to front, feed with a mono signal of perhaps 80 HZ or so.

Bass should cancel out with balance control at centre position. If cancellation occurs with balance control much off centre something is wrong. This, of course assumes that amp is working correctly.

[spendorman]

Mastic and blutac are very different - blu tac goes very very tacky after a long time and is a b*tch when stuck to old crumbling chipwood. Someone opened then up before (to rewire with SPX cable) and did a crap job of getting the drivers out. I really don't want to go through it again after opening them up when I first got them to check them over. Bugger...

You would have to be very careful, but a little heat may help softening the sealing substance, perhaps a hair drier on a low setting.

[cooky]

Mastic and blutac are very different - blu tac goes very very tacky after a long time and is a b*tch when stuck to old crumbling chipwood. Someone opened then up before (to rewire with SPX cable) and did a crap job of getting the drivers out. I really don't want to go through it again after opening them up when I first got them to check them over. Bugger...

The technique as described works for both-it will prevent damage to the speaker/baffle rebate edge though my concern is it is possible to distort pressed frame driver baskets if they are well n truly stuck, so maybe your caution is well placed.

[farflungstar]

Now that the deeper response speaker is in the part of the room that has a weaker response, and the weaker response speaker is in the part of the room with a slightly enhanced bass response things have balanced out - I'm just missing the very lowest octave. Im aware this isn't a solution but until I figure out what to do it will have to do.

[farflungstar]

I've noticed something that may or may not narrow the problem down. The bass doesn't roll off, it cuts off. On electronica tracks where bass on the other speaker goes down very deep, deeper and then expansive and rolling off - the suspect speaker goes down very deep, then just stops, no deeper expansive roll-off. It's abrupt. If it was wadding I don't think it would happen that way?? Hmmm

[walpurgis]

Hmm. Have you excluded the rest of the system as a possible cause? Did you swap the speaker cables from one speaker to the other to see if the issue remains on the same side?

[Pharos]

Sounds to me like a blocked f3, which may be caused by displaced wadding stopping airflow to a port or passive.

[fatmarley]

If the port is tuned to a very low frequency and blocked, it would have the problem you describe. Although, very low frequencies pass through wadding much easier than higher frequencies.

[farflungstar]

I guess in just gonna have to open it up. Bugger

[Pharos]

I agree Matt, but the excursion resulting from Xmax is so high with LF that blockage of airflow occurs, airflow being much less as F rises, and of course the port is ineffective in mid frequencies.

[farflungstar]

Lol - could you explain that in English hahahah

[Pharos]

Xmax is the maximum excursion of a cone in one direction on its axis, which is highest at lower frequencies.

F used for frequency.

LF used for low frequency.

[fatmarley]

I agree Matt, but the excursion resulting from Xmax is so high with LF that blockage of airflow occurs, airflow being much less as F rises, and of course the port is ineffective in mid frequencies.

I'm not quite sure what you're are trying to say.

Below the port tuning frequency excursion Is usually high (can go through the roof with some drivers). At the port tuning frequency excursion Is low because the port is doing most of the work.

(Xmax Is maximum LINEAR excursion)

[farflungstar]

So wadding could account for the abrupt cut-off?

The ANe only have wadding in the top third of the cabinet around the drivers. I've reached into the port and cab touch the inside of the baffle so I don't it's dropped. Maybe it's too close to the driver....

[Macca]

Cold it be the crossover? Something has gone bad and is acting as a high pass filter? Otherwise it is the driver - which must be a weird fault to give the effect described.

[farflungstar]

The driver puts out equal energy down to all but the lowest octave. It then cuts/stops.

[Firebottle]

This seems such a weird one.
You haven't got the speaker in a null in the room response have you? I'm sure it is unlikely but had to ask.

:)

[farflungstar]

No - the opposite in fact. That side of the room has a better low frequency response

[Pharos]

Without wishing to give a full description and analysis which is time consuming and accessible in text books, I think what I have said is clear, coherent, and accurate Matt.

Yes the role of the port is to augment bass and in so doing it reduces the cone excursion at and around f0, and below resonance the excursion of the woofer is decreasingly controlled to the point at which it is not at all, the O/Ps being in antiphase.

The particular ratio of excursion of the woofer and port air is design and alignment dependant; it is not a fixed ratio.

I am merely asserting that near resonance, where the port is functioning, wadding may be impeding the air flow which is relatively high under those conditions. As Colloms said, there should, in a well designed system, be no need for internal damping at bass frequencies, and this implies that there be a large void internally to allow airflow at these frequencies.

Wadding may have been displaced and be blocking airflow at the port.

There are pictures of the inside of Tannoys illustrating just such an approach; the wadding is fixed to the walls to not impede airflow at LF.

[walpurgis]

As Colloms said, there should, in a well designed system, be no need for internal damping at bass frequencies

Assuming it's a totally non-resonant enclosure and ALL energy from the Hemholtz resonance is converted. Of course such circumstances are mythical.

[fatmarley]

Without wishing to give a full description and analysis which is time consuming and accessible in text books, I think what I have said is clear, coherent, and accurate Matt.

Yes the role of the port is to augment bass and in so doing it reduces the cone excursion at and around f0, and below resonance the excursion of the woofer is decreasingly controlled to the point at which it is not at all, the O/Ps being in antiphase.

The particular ratio of excursion of the woofer and port air is design and alignment dependant; it is not a fixed ratio.

I am merely asserting that near resonance, where the port is functioning, wadding may be impeding the air flow which is relatively high under those conditions. As Colloms said, there should, in a well designed system, be no need for internal damping at bass frequencies, and this implies that there be a large void internally to allow airflow at these frequencies.

Wadding may have been displaced and be blocking airflow at the port.

There are pictures of the inside of Tannoys illustrating just such an approach; the wadding is fixed to the walls to not impede airflow at LF.

Sorry for being pedantic Dennis. Text speak always comes across a bit serious or robotic (unless you're a good writer - which I'm not). Anyway, I see what you're saying now.

(Get those drivers out Adrian and have a good look)

[Pharos]

Whether or not the enclosure is resonant or not is a side issue to the fundamental point; of course we want that to be zero, and it never is.

Actually Matt I do not like text speak, my shorthand is from decades ago when they were standard in telecoms and electronics - a taste of things to come.

LF, HF, Xmission, I/P, O/P, numerous mathematical ones and those of course used by speaker designers, eg. Cas, Xmax, F0, F3.
I don't know what BIN is though. (OMG LOL SpkL8R)