Fixing (?) the Madisound Recession Busters (v1). Some measurements.

[fjhuerta]

I've been dissatisfied with the sound of my Madisound RB's ever since I built them.

Considering their price, though, they are a steal.

I just wondered why I wasn't happy with them. I thought it was a lack of adequate BSC, but I also noticed a lack of upper end detail. At first I attributed it to being used to a more agressive sounding tweeter.

So I took some measurements.

Tweeter, on axis, 1M.



If I'm interpreting the graph correctly, there's a hump related to diffraction on the lower end.

Woofer, on axis, 1M. I remember John Krutke stating he wouldn't be surprised to see a hump at 1 KHz with this design. He, as usual, was right.



So, how will all of this look with the Madisound stock crossover? Did they consider diffraction and BSC? My take on it: no, and a little bit.

Here's a graph with the simulated FR, and the measured FR of the second speaker I built with the stock crossover in place. Red trace is the simulated response at 10ms, gray trace is the measured FR at 4ms.

[fjhuerta]

IMHO, the stock crossover leaves quite a bit to be desired.

I tried to fix it up with a couple of components, but it was impossible. The second order electrical on the tweeter can't attenuate the tweeter response enough, the tweeter's impedance hump isn't helping things, and there's just not enough BSC on the woofer. Plus, a bit more control on the upper (mild) peak would be a nice thing to have.

At this point, I wonder how wise of an investment would be to buy the premium version of this crossover from Madisound.

Anyway, here's my fix for the speaker. Every aspect is taken care of - there are smooth 4th order acoustical filters on tweeter axis at 2.8 KHz, phase tracking is extremely close, component count is respectably low, and FR pretty flat.

FR



Impedance



Phase



The circuit

[Operandi]

Very nice, have you listened to the new crossover yet?

Depending on your impressions I might build one with your crossover and one with Madisound's.

[JonMarsh]

Good job, if the overall power response mirrors the axial response changes you've made, they should sound very nice, Javier. Certainly much better than previously.

I know lots of folks are fond of starting every project with an LR2 crossover, but IME it's a rare situation that that is the optimal choice, considering real world driver limitations.

[Curt C]

Nicely done, fjhuerta.

One suggestion: I notice the L3 is 70 uH, and this value may be difficult for many to find, or unwind from a 0.1 mH. You should be able to change L3 to 50 uH, or 100 uH and alter the value of C1 to provide the same transfer function. It’s easier to make up a non standard cap value than source a non standard inductor.

C

[Bent]

I'd agree, I unwound a couple inductors to get the correct value for my Zaph B3S types, and even with my Sencore Henry-meter, I wound up with a heckuva mess and had to use lots of zip ties to put the coil back into shape again.

[fjhuerta]

Thanks for the input!

I need to take some off axis measurements, just to make sure that, indeed, the speaker will have a good power response. It should be an easy task Jon

Curt, good point. I'll post an updated crossover today. I'm used to unwinding coils all the time, but it's a real hassle!

[fjhuerta]

Well, I finally built the new x-over.

Cost: 55 USD without shipping from P-E.

The 1.4 mH inductor is an 18-GA. The rest are 20 GA.

Unwinding the 0.1 mH inductor is very easy. Just take out one layer of windings. That gets you an exact 0.070 mH value.

I also tried an alternate version with a 1.6 mH inductor in the bass, in order to get rid of the 1 KHz hump. Unfortunately, the speaker sounds a bit bass heavy with this version of the crossover.

The results: awesome. The speakers now sound like they should have in the first place. Changes are:

* Far better upper end; more detailed.
* Midrange is a lot more natural sounding.
* Bass balance is restored - now the speakers can be used in proper stands.
* A bit less sensitivity.


I seriously wonder why Madisound didn't include at least a 3rd order electrical on the tweeter. A 2nd order simply won't attenuate its output enough!

All in all - the RB's are still a great value, even with an extra $55 in parts. This is $15 more than the premium version of the stock crossover - for ONE channel.

[herrBender]

very nice work. I have been keeping an eye on this thread for a while.

[wackii]

Good job.

I'm wondering how is your upgraded version compare against the Tritrix Recession Destroyer Kit. I'm temped to build one of these for the surround once I moved in the new house.

Al,

Well, I finally built the new x-over.

Cost: 55 USD without shipping from P-E.

The 1.4 mH inductor is an 18-GA. The rest are 20 GA.

Unwinding the 0.1 mH inductor is very easy. Just take out one layer of windings. That gets you an exact 0.070 mH value.

I also tried an alternate version with a 1.6 mH inductor in the bass, in order to get rid of the 1 KHz hump. Unfortunately, the speaker sounds a bit bass heavy with this version of the crossover.

The results: awesome. The speakers now sound like they should have in the first place. Changes are:

* Far better upper end; more detailed.
* Midrange is a lot more natural sounding.
* Bass balance is restored - now the speakers can be used in proper stands.
* A bit less sensitivity.


I seriously wonder why Madisound didn't include at least a 3rd order electrical on the tweeter. A 2nd order simply won't attenuate its output enough!

All in all - the RB's are still a great value, even with an extra $55 in parts. This is $15 more than the premium version of the stock crossover - for ONE channel.

[exojam]

Javier,

If I am reading your post correctly, you paid 55 without shipping for parts for a pair of crossovers correct? Do you have the part numbers of what you ordered? Thanks.

James

[Txgrizzly]

now thats awesome... you looked at a great buy on speakers and improved on them. Now thats getting your DIY on ;x( ... I would also really like to see a BOM on your crossovers. i am just starting building my own speakers and i am building a set of RS150s right now but my buddy wants me to build him some surround speakers on the cheap and i was looking at getting either Madisounds RBkit or the Reccession Blaster kits. i have to say this hobby can get addictive just like my other hobbies... :roll:

[fjhuerta]

Javier,

If I am reading your post correctly, you paid 55 without shipping for parts for a pair of crossovers correct? Do you have the part numbers of what you ordered? Thanks.

James

Yep, that's correct... let's see.

Image Part Number Description Qty. Ordered Qty. Shipped Price Ext. Price
004-2 Dayton DNR-2.0 2 Ohm 10W Precision Audio Grade Resistor 2 2 $1.25 $2.50
004-6 Dayton DNR-6.0 6 Ohm 10W Precision Audio Grade Resistor 2 2 $1.25 $2.50
027-421 Dayton DMPC-4.0 4.0uF 250V Polypropylene Capacitor 2 2 $1.91 $3.82
027-428 Dayton DMPC-10 10uF 250V Polypropylene Capacitor 2 2 $4.12 $8.24
255-020 Jantzen 0.10mH 20 AWG Air Core Inductor 2 2 $2.58 $5.16
027-427 Dayton DMPC-6.2 6.2uF 250V Polypropylene Capacitor 2 2 $2.68 $5.36
004-.51 Dayton DNR-0.51 0.51 Ohm 10W Precision Audio Grade Resistor 2 2 $1.25 $2.50
255-258 Jantzen 1.4mH 18 AWG Air Core Inductor 2 2 $9.12 $18.24
255-024 Jantzen 0.20mH 20 AWG Air Core Inductor 2 2 $3.24 $6.48

$52.30.

[fjhuerta]

now thats awesome... you looked at a great buy on speakers and improved on them. Now thats getting your DIY on ;x( ... I would also really like to see a BOM on your crossovers. i am just starting building my own speakers and i am building a set of RS150s right now but my buddy wants me to build him some surround speakers on the cheap and i was looking at getting either Madisounds RBkit or the Reccession Blaster kits. i have to say this hobby can get addictive just like my other hobbies... :roll:

It's an addictive hobby, indeed! :T

I spent most of the day listening to the speakers instead of my usual reference, the ZDT3.5 with Duelund-style crossovers. I'm very impressed by the amount and quality of the bass these little things can put out - much more now that is balanced when compared to the rest of the audio spectrum. The little woofer is nice.

Nevertheless, they can't do miracles. In a medium to big room, they sound a bit thin and forward (which is to be expected anyway).

The only downside I can find is that the tweeter can sound a bit too "metallic" at times. I suppose its distortion profile is quite a bit higher than I'm used to, because certain musical instruments sound harder and a bit more brittle than they should. This could be taken care of, in a way, by switching the 2 Ohm resistor in the tweeter network to a 2.7, 3 or 3.3 Ohm. Still, it's obvious other units (like the Vifa DQ25) are a better option these days.

Still -what an absolute *steal* for $59 dollars (+$52 for the new crossover - you can desolder the old parts and use them in another project, anyway). From my odd stash of commercial speakers, I'd say that they are equals to my Energy C-1 speakers now (which used to cost $300 when new, some 5 years ago), my favorite commercial small speaker. The RB's probably have better bass definition and a more balanced midrange, while the Energys tweeter is quite a bit less aggressive sounding.

[exojam]

Javier,

Thank you very much for the information.

One last question, if you were using the RB's as surrounds (as I am), would you still modifiy the crossover or leave it as is? Thanks.

James

[HareBrained]

Javier,

Thank you very much for the information.

One last question, if you were using the RB's as surrounds (as I am), would you still modifiy the crossover or leave it as is? Thanks.

James

Note that these were for Version 1 of the RB. The RB2 which Madisound is now selling uses a different tweeter and xover. This is great for those with the original kit, but not for those looking to buy the current one.

[fjhuerta]

Javier,

Thank you very much for the information.

One last question, if you were using the RB's as surrounds (as I am), would you still modifiy the crossover or leave it as is? Thanks.

James

Hi,

I'd probably leave them as they are... I don't think you'll notice the difference (I could be mistaken). I'd think your fronts and center would mask their output so much it would be a moot point.

Still, if you are a perfectionist, go for it! :T

[penngray]

Great Job!!

I never looked at the RB upgraded x-over that Madisound offers but wouldnt it be close to your performance?

like Exojam, Im using them for surround duties but I have book marked this thread just in case I want to upgrade the x-over on my RBs someday.

[fjhuerta]

Great Job!!

I never looked at the RB upgraded x-over that Madisound offers but wouldnt it be close to your performance?

Not at all. The upgraded Madisound crossover is identical to the stock one, so its performance should be identical (well, some people may argue "X brand capacitor sounds better than Y", but the deviation from neutrality derived from the crossover topology would still be there).

[penngray]

wow! its just more expensive caps? I didnt know that. Thanks!

[oldloder]

Just to be sure, by saying they are now suited to proper stand placement your custom crossover has enough BSC that they really wouldn't be suitable for bookshelf or near wall placement? Does it matter whether they're built ported or sealed? I'm thinking of giving some as gifts and some folks would want bookshelf placement and some might not. Nice work!

[fjhuerta]

Thanks! Yes, it has almost the full 6 dB BSC, so placing them on a bookshelf would boost the bass.

I built them sealed, so a slight boost in the bass doesn't sound too bad.

[Coconutout]

sorry, i totally misplaced this question when i meant it to go to a recession buster reference thread but- the 2FLARE from madisound comes with a rather wide flange thats rough textured. i'm imagining it'is for sound refraction. would it make a noticeable sq difference if i were to eliminate the flange like Rolex has done on his rbr build thread? thanks for your inputs and once again, sorry for waking up an old thread. a sleepless mistake. :P

[cactusjack]

Thanks to Javier For the Crossover Design

I know this is a late post but I just built one of the referenced new crossover networks. Just got about 100 hours on the new crossover. I could not be happier. The bass is better controlled and mid-range is clear and smooth. The tweeter is also better matched to the woofer.

Thanks Javier for the design to improve the RB-1 speakers. I am much happier with your designed crossover.
Have a great holiday season
Warmest regards,

[fjhuerta]

Thanks cactus! Glad you liked it. Actually, the RBs are my main listening system, since I use them at the office, and I am extremely impressed with the quality of the drivers (I guess I got used to the tweeter's sound by now). It was a great buy

[oldloder]

Unwinding the 0.1 mH inductor is very easy. Just take out one layer of windings. That gets you an exact 0.070 mH value.

This would be unwinding the outside layer of the coil, right?

[xyrium]

Hi Javier,

Do you have graphs of the new output?

Thanks,
Paul

[ThomasW]

This would be unwinding the outside layer of the coil, right?

Yes..