The Effect of The Soundlab Subwoofer Panels.

[Earlinarizona]

I have a great ‘Roger explanation’ for why there are 2 transformers , just not sure if there is interest?

For sure YES

[RW]

Jim Strickland at Acoustat took the same dual transformer approach with his interfaces. Compare the comparatively tame impedance curves of either SL or Acoustat to the roller coaster profiles of single transformer models like Quads, Innersound (now Sanders), etc.

https://www.stereophile.com/content/innersound-kaya-reference-loudspeaker-measurements

[ChrisSoundLab]

Wow, roller coaster for sure.
Interestingly Acoustat had a pretty good following here in Japan, perhaps a lot to do with their narrow profile and fitting Japan’s smaller room culture. Two customers of mine who had ‘expired’ Acoustats were so happy and satisfied with the new slim SL models.
🙂

[ChrisSoundLab]

OK, here it is attached

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[Earlinarizona]

Your last post cleared up a bunch of things and it showed that the cell spacing had no tweeter area and the Bass Panel backplate which is perfect. I have attached the owners manual to the UB800 and it does say 50 ohms but here is where I am getting mixed up. With your impendance curve at 20HZ it reads 30 ohms and at about 500hz it is about 9 ohms.So where does the 50 ohms specification come from? I didn’t know if the transformers were different or something else at flat settings. That was my puzzling question. It may be if you measure the impendance curve on the woofers, it may be very different. That was my curious question.

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[ChrisSoundLab]

Thanks Earl, I was going to scan my owners manual too but I’m out in Tokyo for the weekend. I have the same question on the 50ohms nominal and I’m asking Roger. The backplate uses the same bass transformer, (just in case some people don’t know, there are 2 transformers used in the full range panels – one for bass and the torroid which is used for mid~ high frequencies) I have a great ‘Roger explanation’ for why there are 2 transformers , just not sure if there is interest?

I’ll get back to you on the impedance rating.

[ChrisSoundLab]

Hi Earl, well … I am unclear to what question I am answering except that it must be something to do with the bass panels as that is the title of this new topic?
Let me start by attaching the impedance curve again (for full range) and a couple of photos.
Bass panel backplate – looks like this (mine has 2 sets of posts to by-pass controls if preferred)
Panel photo with arrows to show where I have marked tape to show the spacing on the vertical axis of cells – similar to full range panels for ‘bass focus’ and distributed resonance.

I don’t have impedance curve just for bass panel, but it will vary depending on the control settings – which can be set up to 1000hz …as you can see the impedance is high at low frequencies and dips and then rises again to around 15ohms around 1000 hz.

Thus keeping in mind this is not a ‘subwoofer’ that is dedicated to very low frequencies, it is instead additional energy to support the full range panel especially good to help larger rooms where there will be more bass cancellation.

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[Earlinarizona]

I think Chris JP can answer this question.
On your home system the front speaker have the 845 and another set of panels next to them that you use for bass.
Are the speaker grids the same as a normal fullranger SL or are they spaced like the UB800 dedicated subwoofer?
Does you backplate have a damping / Rolloff knob or the same knobs as the regular line?
The UB800 and 900 are 50 ohms compared to the normal 8 ohms too. You kindly published the impedence curver for the regular SL’s but could you publish the same thin for the bass panels.
Chris, I have to thank you for waking up not only this forum but the YouTube channel with real recordings and What’s Best Forum.

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