ZD5 Damping (+crossover pic)

[valleyman]

I am just about to finish my new ZD5s and was wondering about damping. I have lined most of the insides with acoustic laminate panels from wilmslow, that's 2mm bitumen and 10mm foam.

I have then additionally lined the top and most of the back with BAF also from wilmslow.

This is my first speaker build so I have no experience with stuffing. I have posted a pic below so you can see what I've done.

I have also posted a picture of my crossover layout. It probably isnt the best (as I said, first one), but I have tried to minimise inductive coupling.

Thanks for any help

[valleyman]

Also, I should mention that I have the boxes closed up and drivers mounted and impressions are VERY positive. I want to do some more listening before saying they're awesome though.

One thing to note... I'm very glad I went for the sealed over vented configuration. Even in the sealed box, the bass from that scanspeak woofer is amazing and the vented box would have been way too bass heavy for my small room

[JLC7]

Looks nice. Are you going to mount your crossover to anything? It won't take much for a joint held strictly by solder alone to break.

A good solder joint is a good electrical connection even without the solder (excluding surface mount components). When possible you should try linemen splices for added strength and durability.

http://workmanship.nasa.gov/guidadv_...h_wusplice.jsp

It's probably more important for when I wire race cars, but hey, if people are willing to spend $1000s on speaker cables, the least you could do is make sure you have a solid soldered joint.

[valleyman]

All those components are glued in place with Bostik extra strength clear adhesive. I made the very fortunate discovery that this glue seems to slightly melt whatever that foam is made of and bonds to it very strongly, but more importantly, it does so instantly. Just slather the component with glue, press it in place and it's stuck in 5 seconds. This glue is available in Tesco for less than £1 a tube.
That weave looks good, but time consuming and difficult to execute. I'm confident that a knock that would dislodge my crossover would probably break the cabinet first, so no huge concern.
I posted the crossover layout mainly because I hadn't really seen a pic of a completed ZD5 crossover around and thought it might make life easier for another builder.

What I really would like some advice on though, is how much damping is required and where. As I said, this is my first build so I don't know what to listen for to know whan I've got it about right.
It would be great if someone else who has built ZD5s could let me know what they used or maybe someone could point me in the direction of some good info on damping sealed boxes.

Many thanks

[valleyman]

From what little info I have been able to find on the web about this (I must not know where to be looking) I've now gone with all the walls lined with 2mm bitumen and 1cm foam sheets.
Top and back are then lined with around 1" BAF and 1" wool. Bottom is lined additionally with 1 inch BAF
1 side lined with 1" BAF.

This seems to have worked fairly well and I'm stunned by these speakers. I take my hat off to Mr Krutke and offer my sincere thanks for the design. Even with my fairly crude woodworking skills these speakers are astonishing. The clarity and cleanliness of the guitar in "Map of Your Head" by Muse summed everything up.
The bass is also very impressive for a sealed box of this size and is more than sufficient for a small room.

I'd still like to hear from anyone else who has built these about how they stuffed them.

Many thanks

[kamppi]

It is quite easy to test what is correct amount of damping material for your taste. Add little bit more material to bottom and roof. (Specially bottom) It is also good if the wall behind the bass driver is damped properly. After that make a listening session. If the sound was better, then you can add small amount of material to critical places. Check also if it is possible to put material to the front panel. If the sound gets worse take material away little by little. This will take some time, but it is worth do it and it is not too difficult.

[valleyman]

Hi Kamppi, thanks for the reply.

Unfortunately, while I understand how to go about stuffing them correctly, it is doing it in practice I have problems with.

By the time I have unloaded the drivers, altered the stuffing, reloaded the drivers and replaced the speakers I am unable to compare fairly if they sound better or worse than before. In fact it is fairly well extablished that listening tests are pretty inaccurate unless they are done as blind A/B tests. I trieddoing A/B tests using only 1 speaker each with different stuffing in each, but unfortunately with only 1 speaker playing, no matter how I stuffed them they always sounded very poor (not really surprising) and I gave up on this as a possible way of proceeding.

I'm still hoping someone who has built these speakers and has a keener, more experienced ear than I will chime in and offer some advice.

Many thanks

[JLC7]

Muse are awesome. That's all I can say.

The way I'd go about tuning the amount of stuffing is to take measurements with a mic. Whatever amount of stuffing gives me the desired tuning frequency is the right amount. It's also up to preference as increased stuffing will tend to dampen midbass.

If you don't have measurement equipment maybe you could try stuffing the speakers at two extremes? Maybe overstuffed and without stuffing just to see if you can train yourself to hear a difference.

[valleyman]

Good news!

I had a couple of friends over today who are good musicians and both have very keen ears.
I did in fact go for the "different stuffing in each speaker" method and I stood by the amp and instantly switched speakers during songs and we eventually came to a stuffing consensus.

I had definitely over-stuffed the speakers before and here's the optimum stuffing we unanimously decided on.

Top: 2mm bitumen, 10mm foam, 1" BAF, 1" wool
Back: 2mm bitumen, 10mm foam, 1"BAF and the top half covered with 1" wool

Bottom: 2mm bitumen, 10mm foam, crossover mounted, covered with 1" BAF

Sides: 2mm bitumen, 10mm foam only.


One thing I should say though... everything was a tradeoff.
More stuffing meant better bass, but less clean mid/highs
Less stuffing meant weaker bass but cleaner mid/highs

The tests were not blind, but the switches were done usually in less than half a second and often without eve interrupting the flow of the song which makes it much easier to do a fair comparison.

I'd still be intrested to see how others have stuffed their ZD5s but I hope this information can be of use to others. I've learned a lot here and it's nice to be able to give something back, however meagre the contribution may be.

Many thanks

[kamppi]

Hi,

I have ZD5 speakers. I do not have bitumen in my speakers and I have bass reflex cabinets, but ports are stuffed. The shape of the cabinet is also different. Width is the same, but depth and length are different. I think that we can not directly compare the way how the speakers are stuffed. Maybe I will take away some stuffing material, since now the cabinets are almost closed. I am already quite satisfied with the midrange, but I am even happier if it can be even better. Thanks for the hint