Speaker enclosure filling

[Lawrence001]

This stuff, I use the E shape one.

https://www.ebay.co.uk/itm/18564954...TfoM5DWSmi&var=&widget_ver=artemis&media=COPY

 

[lostwin]

Much delayed after Evri lost my parcel, I finally received the fibreglass wadding. This is the stuff that is primarily used for motorbike exhausts.

First surprise when removing my mid range driver and taking out the existing home insulation type filling, was the length of the driver tube enclosure. My memory had this as about 25cms, actually it is just 9cm deep and 11cm diameter.

Old stuffing was pretty tightly packed filling out the whole space and wrapping round the driver magnet and frame. Also, as it would have been about 5cm thick it is effectively a roughly formed blob once squeezed in place.

The new wadding is in sheet form, a little under 1cm thick and denser with the glass fibres being woven together. As such, filling the enclosure is more structured with shapes cut to line and discs to fill out.

I have tried 3 levels of filling from about half filled fairly loosely to fully filled fairly tightly. The latter works best, the looser filling emphasised some mid range resonances whereas fully filled is more even and seems have a fuller tone.

Pretty pleased with this. A sheet of wadding cost £15 and I still have half of it left. A good start to another year of tinkering !

Thanks to @Fatmarley for the wadding tip

 

[lostwin]

Oh, and I also followed @Lawrence001 advice and changed my driver seal from blu-tax to rubber window seal

 

[lostwin]

Further listening with the tightly packed wadding - which I had initially preferred - revealed a persistent darkening of tone which I couldn't get on with. So I have dived inside the enclosures again and used the suggested loose rolling method - a bit like a Swiss Roll - in the space behind the magnet (only about 5cm depth) along with a little extra wadding around the driver frame. Seems better balanced now.

It's pretty easy to do and low cost, so if you have a mid driver with an enclosure behind and want to adjust for slight brashness or seek some extra sparkle, then adjusting the amount of damping material is an option to consider. This type of fibre glass wadding is nice to use, has minimal shedding of fibres and is non irritable.

 

[MF 1000]

You could also try some plasticine on the back face of the driver frame to damp out any ringing

 

[lostwin]

This is obviously a winter tweak itch, as a year on I am about to dive back inside the speakers for another fiddle.

I have a rattle in one of the bass units that I will track down and fix , plus I have got some new neoprene tape to use as a gasket to remount the drivers.

A couple of questions on the mid range enclosure. This is a 5” cardboard tube with 4” driver mounted in front. The tube is blocked off with a flat chipboard disc creating an enclosure depth of 4”. It is packed with fibreglass exhaust wadding as recommended in this thread last year.

Should I consider adding some rigid profiles to the rear blanking disc to break up standing waves? Any ideas on shape and size?

Would it be worthwhile to wrap the cardboard tube externally to dampen it?

The mid range driver covers frequency range roughly 250 - 2500 hz.

Any thoughts?

 

[tuga]

This is obviously a winter tweak itch, as a year on I am about to dive back inside the speakers for another fiddle.

I have a rattle in one of the bass units that I will track down and fix , plus I have got some new neoprene tape to use as a gasket to remount the drivers.

A couple of questions on the mid range enclosure. This is a 5” cardboard tube with 4” driver mounted in front. The tube is blocked off with a flat chipboard disc creating an enclosure depth of 4”. It is packed with fibreglass exhaust wadding as recommended in this thread last year.

Should I consider adding some rigid profiles to the rear blanking disc to break up standing waves? Any ideas on shape and size?

Would it be worthwhile to wrap the cardboard tube externally to dampen it?

The mid range driver covers frequency range roughly 250 - 2500 hz.

Any thoughts?

Are you able to measure the response of the midrange alone? If there are substantial resonances these will show on the impedance plot.

Edit: instructions below

https://www.roomeqwizard.com/help/help_en-GB/html/impedancemeasurement.html

 

[lostwin]

Are you able to measure the response of the midrange alone? If there are substantial resonances these will show on the impedance plot.

Edit: instructions below

https://www.roomeqwizard.com/help/help_en-GB/html/impedancemeasurement.html

Possibly. I have had a quick dabble with REW in the past but have struggled to calibrate the mic as I have a non USB one.

In theory, , should I be minimising the reflections from the rear of the speaker enclosure? This might be a bit bonkers, but I am considering trying these security spikes as a way of doing this
https://www.ebay.co.uk/itm/30523337...Y5gyFO3TOy&var=&widget_ver=artemis&media=COPY

 

[bencat]

Richard I have a MiniDSP Umik mix you could borrow it it would help ? Just my very uneducated addition to this . Whenever I have found a speaker I really liked it seemed to be those designed to be then skinned and packed with very lightweight stuffing . So in my view filling the space but with lightweight material is the way to go . One material that I have read about and here in one instance which seemed to be very effective was bubble wrap mainly the larger cell type rather than the very small one . They can very easily fill a space tightly and the air in the enclosure becomes a set of small separated cells which break up any resonances as they pass through each individual space .

 

[lostwin]

Richard I have a MiniDSP Umik mix you could borrow it it would help ? Just my very uneducated addition to this . Whenever I have found a speaker I really liked it seemed to be those designed to be then skinned and packed with very lightweight stuffing . So in my view filling the space but with lightweight material is the way to go . One material that I have read about and here in one instance which seemed to be very effective was bubble wrap mainly the larger cell type rather than the very small one . They can very easily fill a space tightly and the air in the enclosure becomes a set of small separated cells which break up any resonances as they pass through each individual space .

I appreciate the offer on the microphone, let me see how the weekend experiments go and I might take you up on it. When I changed the filling to the fibreglass exhaust wadding last year, I could hear by ear how the different levels of stuffing changed the sound - that still seems more practical than the mysteries of REW.

I have some more wadding to try in the bass cabinets, but if I don't like the results then bubble wrap is an alternative.

 

[tuga]

Possibly. I have had a quick dabble with REW in the past but have struggled to calibrate the mic as I have a non USB one.

In theory, , should I be minimising the reflections from the rear of the speaker enclosure? This might be a bit bonkers, but I am considering trying these security spikes as a way of doing this
https://www.ebay.co.uk/itm/30523337...Y5gyFO3TOy&var=&widget_ver=artemis&media=COPY

Have a look at the instructions I posted earlier, you won’t need a mic:

REW can make measurements of impedances up to a few hundred ohms by using both inputs of the soundcard.

 

[lostwin]

Have a look at the instructions I posted earlier, you won’t need a mic:

REW can make measurements of impedances up to a few hundred ohms by using both inputs of the soundcard.

Ah, ok - it does look beyond something I would be confident my electrical knowledge can cope with though and I really don't want to mess up the mid driver, as they are virtually irreplaceable now days.