Quad 11L filter & cabinet upgrade

[Malefoda]

Hi there,

here is the Quad 11L stuff (mine, victim of my willing to get the best of what I've in hands...)


The victim:


Filter in the cabinet:


Filter:


and mixed:


French guys advised me to fit the cabinet with sound deadening mat in the inside back of the cabinet, inside bottom, famous green wool in half instead of the black.
How about the filter guys?

Thanks,
Matthieu.

[SimontY]

Hi Matthieu,

It's hard to make out the exact circuit from the picture (for me at least), but I'll guess the film cap is in series with the tweeter. This will be fine but you could try an expensive cap if you like. Even a Maplin / LCR film cap would be nice.

The resistor will be in series with the tweeter. I'd change this to a 5w Kiwame.

One of the 'lytics will be in parallel with the bass driver for the 2nd order part of the filter, and you could change for a cheap film cap. I can't work out what the other cap's doing, but you could just change it for a cheap film cap too. It won't hurt, and will give a more accurate value than the 'lytic.

The inductor in series with the bass driver should be changed for an expensive heavy-gauged air-cored type, if you want to mess with it.

The cabinet looks like chipboard, which is fine as it has a pleasant character. For less vibration you could try adding mass with bitumen. You could also add some dowel bracing to connect adjacent panels.

Another trick would be strips of bitumen on the bass driver basket spokes.

That's probably enough ideas for now.

Simon

[jimh0612]

Hi Matthieu

Firstly I know nothing about building or modding speakers!

However another mod I've seen suggested (apart from the cross bracing between sides) is to take turns off the coil one by one to tune the frequency response of the crossover/ rolloff but I'm not sure which.

He suggested removing the wadding and fitting the sound deadening mats we use in the CD63/53 etc, but I'm not sure what the effect would be - he liked it though. Same as Simon's idea.

His other idea was to coat the crossover in Blu-Tack or similar to stop vibrations, for the same reasons we add damping material to the case of our CD players.

Oh, and Blu-Tack between the driver chassis and the cabinet to improve the seal.

I haven't had the time or nerve to touch my pristine 11L's in case they become no longer pristine!!

I'm sure you're in good hands with Simon as he's built some very good speakers by all accounts.

Good luck.

[SimontY]

You'll want some kind of acoustic damping material in there, not just bitumen. You need something to control standing waves. My personal favourite is carpet underlay, but only a specific type. The foamy ridged variety sounds much better than the standard acoustic wadding or profiled foam. You'll hear better mids and bass. To tune you could add some lamb's wool (if you find the midrange has become resonant). If you try the underlay I'd suggest covering the rear panel and one of the sides and the top.

I'd not bother with the blue-tac on the x-overs, as it won't do a lot for the sound but it will make the parts hard to access.

Simon

[gainphile]

This is very expensive Quad speaker right? I wonder why the crossover is so simple. What about fs compensation etc ?

[SimontY]

Originally posted by gainphile
This is very expensive Quad speaker right? I wonder why the crossover is so simple. What about fs compensation etc ?

It's an upper-budget speaker, it's not expensive. I'd say the money has gone into the bass driver and veneer: the two most important parts for good sound and good looks!

[Malefoda]

Thanks fellows, yes that's very good budget speakers.
I'll go for damping, but what do you mean by brace between sides ?

Right now it's:
Half synthetic black wool changed by a french good one (green named "Thibaude"), top and one side still black, other side and bottom the green one. Under the wool and in the back inside some sound mat.
About caps I'll go for simple MKP from Mundorf or Russian PIO or such for the blue cap (// with bass unit) and good caps (Mundorf, Auricap, PIO...) for the series Yellow... and bad looking black.

Now I've to make a wise choice according to price and what people advise me as good caps.

Already a big thanks as I've got almost all the answers within minutes!

[SimontY]

Hehe, I like to help when I know someone will be getting stuck in, as I'm sure you will be

Actually I'm just looking inside my crappy Tangent Monitor 6 speakers. This prompted me to look. In my current situation I can't listen to my big ones, so I'm gonna have to mod these, they're very poor.... And no wonder - they contain tiny elco caps and teeny-weeny coils!!!!

[jimh0612]

Hi Matthieu

Brace between the sides to help stop the cabinet vibrating.

Cut a piece of fairly thick dowel (round section wood) to the exact width of the inside of the cabinet.

Make it a good tight fit, so better to cut it slightly too long then cut a little off again.

Put it inside the cabinet halfway down, so it is in the centre of the sides.

Check that the driver chassis does not touch it, then take it out and glue it into place.

Use good quality woodworking glue. (sorry that's the craftsman builder in me coming out!)

That should help to stop the cabinet resonating.

Simon is probably right about the Blu-Tack!

Good luck. Jim

[SimontY]

That's exactly the kind of brace I had in mind!

As a bonus you could position it precisely so that the rear of the bass driver rests against it. This is a good idea if you can position the piece of wood with sufficient precision.