SB Acoustics monitors build

[rpb]

What stuffing is being used to absorb the woofer back wave?

Is the impedance "normal" above 20k? Any chance the amplifier is doing something like overloading? Maybe the impedance is a difficult load.

I may take a stab at a sim tonight. What xo point do you think is optimum?

How does the woofer measure at 45 off axis?

[DeZZar]

It's sort of a similar story on my current two way floor standers, same tweeter. Most music sounds great, including a lot of rock, but then sometimes you play something that sounds pretty good on the sonos for instance, but drills a hole in your head on the big speakers. It's odd, you sort of just get hit with this wall of trebble that magically makes all the bass disappear leaving you wondering where all the warmth and depth went. But you look back at the measurements and its running a 5db downwards til from 100hz to the top end without any nasty peaks. Theoretically 100hz is the loudest point. But the tsunami of trebble from a lot of metal tracks just completely takes over. It's something I'm hoping to improve with version 2 of those. But maybe I'll try another tweeter as well. It'll take some experimenting. Should take a measurement of the sonos one day ...I'd love to see what frequency response it is that makes everything generally sound fine.

Maybe I'll pick out a few tracks and get some of you guys to play them and tell me what you hear. I might just be getting really fussy.

[Geoff Millar]

How do the same rock/metal tracks sound on your other speakers? I ask because some albums, such as my pet hate sound-wise, the Red Hot Chili Peppers - sound quite harsh on our good speakers, but are almost tolerable on speakers with muted treble, such as our little 'Panasonic' bookshelf system.

Maybe your SBs are revealing harshness in the recording/mixing?

Geoff

[DeZZar]

That 5.5 ~ 7.2 KHZ region is what is biting your ears - its too hot - try some EQ in that area with the Rock music again

You would think so, but I've slammed the door shut on that woofer with eliptical filters and still the same. There seems at this point to be little difference between a fourth order eliptical and a second order with tank.

For a lot of music, the tweeters not really working that hard. When you disconnect the woofer it surprises you how little it seems the tweeter is doing. However, when you throw on some metal, suddenly the tweeter really comes to life.

EDIT:
Sorry - miss-read your post. Thought you were referring to woofer breakup! Yeah next round I'm going to try leveling out that tweeter top end and see if that improves it!

[Steve Lee]

That 5.5 ~ 7.2 KHZ region is what is biting your ears - its too hot - try some EQ in that area with the Rock music again.

[DeZZar]

I've come up with several crossovers so far and tried a few of them. The speakers sound nice and when you get the balance right the bass is really solid from such a small setup.

I haven't really decided which topology to go with yet as they are currently all sounding quite similar. Here is the measurement from my last attempt but not quite where I want it just yet.


This still sounds fairly bright on some material - jut about everything from Jaz to pop sounds excellent but when you get into some rock/metal the tweeter just sounds like it takes over - not really sure why given its level is suppressed and basically flat - several db below bass levels - I've had this challenge with this tweeter before and I'm starting to think maybe its just not a great tweeter for metal - I could be (and probably am) wrong.

Irony is my neighbor is completely stoked with what he hears so at this stage its just my fussiness that's stopping me from putting a bow on them!

I'll keep tweaking and post up my schematics shortly. In the meantime - anyone else is welcome to take a crack at it

[DeZZar]

Quick update for everyone interested in this build. Measurements are in and I thought I would attach them here in case there is a guru out there that would like to try modelling something up.



Few challenges with this one. Woofer breakup hits nearly 20db above target and the 3K mess on the tweeter is diffraction.

[DeZZar]

Getting the measurements underway now. I've started with just the woofer/port near field because there is a barking dog next door that just wont shut up!! I suppose that gives new meaning to measuring the woofer....heh heh...

Anyway, good opportunity to compare the modelled box response with what we actually achieved and I'll run the far field later.

Here is the woofer and port nearfield with the port scaled and combined response (blue).



Looking over the data in a little more detail here is a normalized comparison of the winISD model vs the actual result. (I've normalized it all to the level at 200Hz).

I'm really happy with this and actually consider it to be pretty good alignment between the model and result. An extra bonus is that with the port tuning right on 40hz we've achieved further extension of F3 than predicted without sacrificing any magnitude in the preceding octave.

From an expected F3 of 45.5Hz we've got ourselves 42.3Hz. Not bad for a 6" woofer in 15L

[DeZZar]

Hey I would love to have neighbours into DIY! It'd be awesome! Not enough DIY'ers around these days!

[Unbiasedsound]

I wish I was dezzar's neighbor. lol

[DeZZar]

I've done something similar in the past with a piece of plywood I cut to the right diameter.

I thought about that too with a scrap of MDF but it was getting late into the evening and I didn't want to make anymore noise with the router - so thought I'd set the printer going instead! But making a wooden wheel with a bandsaw or router circle jig is definitely a faster option!!

I can see this happening again in the future and its got me thinking about creating a jig that can take different sized outer rings to sand to different diameters...something more substantially centred on bearings that runs true.....hmmmm

[DeZZar]

Thanks Scott!

I really like the veneer too but I haven't been able to get anymore of it unfortunately. Will definitely keep my eye out for it. In case you find some in the future, its Tasmanian Blackwood.

[DeZZar]

Yeah still the best tool in the shop I'd say! I'll been wanting to try some TPU but they say the ender needs a few little upgrades to handle it well...

[invaderzim]

and the award for "Best Neighbor Ever" goes to..... DeZZar.

[jvphotog]

Love seeing your Ender at work. I just used my Ender5 to make some gaskets out of TPU for a Faital waveguide. Such an awesome tool... when it works!