Erin's Audio Corner Review of the Samba

[LOUT]

Some of the review might sound a bit negative for the on-axis FR, but it was a Klippel measured review and raw driver (woofer/tweeter on baffle) measurements/FRD files are also shared for anyone looking to tweak XO bits. I'm curious how much of the non-linearity (small as it is, I think at ~+/-3db) is due to the original measurement/listening methods used during designing VS driver manufacturing changes over time VS whatever else may come into effect.
The overall kit and parts quality is still praised and it might be an interesting thing to look at if anyone here wasn't yet aware of the review.
https://www.youtube.com/watch?v=gj5dE897O54

[Geoff Millar]

Thanks for the link: very interesting viewing, but the reviewer doesn't say what it sounds like....

Geoff

[LOUT]

Hey, you're right! In most/all the other video reviews I've seen from him, he starts by giving a subjective review of how the speaker sounded in a couple different rooms.
I'm happy to have the measurements and explanations for things, but that's also in the written reviews while I think his subjective listening opinion is usually just in the videos, so that's a pretty odd thing to leave out.

[Steve Lee]

His measurements and review reflect my initial observations as I had installed SEOS-8 waveguides over the tweeters to bring the vocals/low treble up in level but ultimately I grew accustomed to the Samba kit sound and mixed a lot of drums upon them.

Now that I am looking at his data I cringe at the possibility of having to go back and redo all that effort.

I may just rebuild the Sambas using the SEOS-8 waveguides at some point as they definitely sounded more flat/alive in response with them.

Reference --> Starting with post # 4 here --> https://techtalk.parts-express.com/f...oak-and-walnut

I think they would look and sound better with the waveguides upon them.

Thanks for the link LOUT - more projects for my old age . . .

:D

[LOUT]

I wouldn't have thought to add a waveguide, but that makes a lot of sense for picking up the tweeter's drooping low-end. I suppose that does put it into a total rebuilt territory though...and changes it compared to the w/oXO measurements from the review page (I don't think they were shown in the video). Though that might not matter as much when you have your own measuring equipment.

[LOUT]

Around 24-25minutes into the video he has the w/oXO driver+cab measurements plugged into VituixCAD while using a simulation of the XO....but it looks like the 1ohm resistor on the woofer's cap-to-ground might've accidentally been replaced with a 10ohm resistor.
The video's resolution (after youtube's compression mangling) makes it difficult for me to tell if it's a "10" or a "1.0", but pulling up a slightly less antiquated version of VCAD that I have (still not the newest, which he might be using here) it appears the program does NOT add a ".0" to the end of 1ohm resistors in my version...so he might've typo'd this one bit at the end. Not that it changes the actual measurements or anything else, but it might explain why the woofer's simulated slope looks so shallow.

EDIT: I went to the actual website review that has the same image of the simulation that's easier to read, and it DOES show a 10ohm resistor(+7.5ufCAP) to ground on the woofer. I'm pretty sure it should be a 1ohm in that place.

[ErinH]

The original file had the 1 ohm resistor. I played around with the components a while and then put everything back. Fat fingered that number. This is the final result, though, with correct values. I’ll update my site later.

As for how it sounded? Not good. Muffled in midrange, a bit “forward” in the 1-2k region and “bright” (likely thanks to the crossover dip). This all jives with what I saw in the data (which is always after I listen to the speakers).

[LOUT]

Thanks for the update and your listening experience. It's exciting to see more Klippel measurements of DIY designs and the XO-less files are super cool to have, so thanks for that too.

[Steve Lee]

Erin, Thanks for your review of these Samba speaker designs - it helps me to trust my instincts/ears and question what I am hearing more-so now.

There was a lot of discussion/debate at the time I assembled this kit and also tried learning about passive XO's using XSim at the time - we got a lot of pushback for questioning our findings with the Samba XO design only now to be found to have been headed in the right direction.

Technology changes and the world changes and we all have to come to grips with it - ego's aside.

I'd love to see someone make an XO for the Sambas that reflect the new information you have delivered.

Thanks again, Sir.

[JRT]

The original file had the 1 ohm resistor. I played around with the components a while and then put everything back. Fat fingered that number. This is the final result, though, with correct values. I’ll update my site later.

As for how it sounded? Not good. Muffled in midrange, a bit “forward” in the 1-2k region and “bright” (likely thanks to the crossover dip). This all jives with what I saw in the data (which is always after I listen to the speakers).

They must have sent you the wrong loudspeakers, something other than the Sambas they are advertising. The loudspeakers that you reviewed do not seem to fit the description on the Parts Express marketing webpage which states, "The Samba speaker kit delivers reference quality sound with natural high frequency response and powerful low end capability. This premium design produces pinpoint imaging, revealing detail, and flat response with minimal distortion." And they further state that it exhibits "Incredibly flat response throughout the crossover region, ±1.5 dB from 500-15,000 Hz".

That does not seem to align well with the loudspeakers that you reviewed. They must have sent the wrong kit, as what else could cause such a large discrepancy?

[ErinH]

Have to admit, I laughed at this post because I thought you were being sarcastic. But, in the event you are serious: Wouldn't be the first time a manufacturer thought their product was something other than what it is. If you look at my impedance data vs theirs you'll see it aligns. Then you can compare their FR vs mine and see the results are similar with the exception being the midrange/LF rise which is attributed to nearfield measurement. We know NF measurements exhibit a 6dB/octave rise in the LF and should be corrected for in simulations where proper anechoic measurements are not an option. PE knows about my measurements because I sent them results. Hopefully they'll make appropriate changes to the XO.

[JRT]

Yes, I was being sarcastic. The marketing blather seems to be describing some other loudspeakers.

[LOUT]

Anyone have any ideas why the P.E. measured FRD for the RST28F-4 seems to think the tweeter's response above 3khz is 5-6db louder (higher sensitivity?) compared to the Klippel results?
Normally I'd guess maybe PE accidentally shifted the whole response up by 5-6db when adjusting the graph to 2.83v VS whatever the response was measured at, but the PE measurement seems to match pretty closely to the Klippel below 3khz so that kind of mixup doesn't seem likely.
I'm also pretty sure bafflestep differences between halfspace and fullspace measurements would usually make more of difference below 3khz rather than above, so a BSC mixup doesn't seem to make sense for this.