DIY Amphion Bases Prject

[F Jell]

@MAB: thanks for the outstanding hint L26ROY+2xSL26R with 200g each in a 40l enclosure.
I’m right now designing a column speaker and only need a further SL26R.
What is your recommendation of placing the 2xSL26R?
Because of takeover to the mid, the L26ROY is placed close to the mid SESS W18NX003, this will be in a high of 60 cm (circle center) on the front. The
2xSL26R can be placed on the right/left side at a high right beyond the L26ROY, so that the 3 do not block each other in deep.
Have you ever tested such configuration?
By the way do you have the QMS of the SL26R in your hand for simulation in winisd. I found QMS 14 in the web, but this is not official from SEAS.

 

[MAB]

@MAB: thanks for the outstanding hint L26ROY+2xSL26R with 200g each in a 40l enclosure.
I’m right now designing a column speaker and only need a further SL26R.
What is your recommendation of placing the 2xSL26R?
Because of takeover to the mid, the L26ROY is placed close to the mid SESS W18NX003, this will be in a high of 60 cm (circle center) on the front. The
2xSL26R can be placed on the right/left side at a high right beyond the L26ROY, so that the 3 do not block each other in deep.
Have you ever tested such configuration?

The two passive radiators can be placed anywhere except down or up-firing (they will sag over time with that weight added!) Opposite sides of the cabinet like you plan are ideal since the opposing motion of the radiators will cancel each other out. And at resonance the passives move massively (just like the air in a port moves maximally at resonance, the passives act as a massive port!) The configuration you plan is similar to what Seas recommends as an alternative to their KingRO4Y on page 6:
chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/http://www.seas.no/images/stories/diykits/KingRO4Y_MK.III/SEAS_KingRO4Y_MKIII_ApplicationNote_AssemblyGuide.pdf
The subwoofers I built are the same opposed radiator placement. So you are good!

Lastly, you can extend the volume to about 85l, which is more optimal than the Seas app note. You will get slightly more bass extension this way.

By the way do you have the QMS of the SL26R in your hand for simulation in winisd. I found QMS 14 in the web, but this is not official from SEAS.

QMS=14 is correct, according to Seas technical support. I had asked this and Grethe Årum from Seas, he provided that number, Madisound posted it, I don't know why Seas has not updated the Spec sheet. They are better than most, but still leave lots of room for improvement...

I also note that Amphion has a new monitor with the excellent Seas L26 woofer in a sealed box.

New Amphion One25a Active monitors

New ACTIVE Amphion monitors being released at NAMM. https://amphion.fi/news/amphion-announces-first-3-way-active-studio-monitor-one25a/ -3 way 10” -2 sealed boxes -1100 watts in 3 amps -soffit mountable -22Hz-22kHz-3dB -expensive

www.audiosciencereview.com

You are going to have some great bass.

 

[F Jell]

Poah, how deep you are in that field, congratulations.

Good to know to be allowed to raise the volume (40l) as quite less for a column speaker.
Looking at the “normal” size of such column (1050x290x350 to 400 deep) I might get about 60 to 70 liters free for the sub.
Winisd shows also a much broader gain.

Cabin 70l
Blue: 1 26roy + 2 SL26R + 80 g
Red: 1 W18NX003 - 10 liter

You calculated 40l + SL26R + 200 g for Helmholz resonance 20 Hz, isn’t it?
Doing so with 70l we are at 80g each?

Also it seems that when having the 26roy the cabin sides (left, right) needs more stiffness.
FinkTeam tells us with their new BORG

Test FinkTeam Audio Borg: die neue LowBeats Referenz - LowBeats

An diesem Lautsprecher scheint vieles zuerst außergewöhnlich: Eine Standbox, fernab von gängigen Des

www.lowbeats.de

Thanks for your sharing your expert thoughts.

By the way:
high will be Mundorf AMT25CS2.1-R
2way active minidsp PWR-ICE250 drives 26roy and Mid/high with passive crossover

 

[MAB]

Poah, how deep you are in that field, congratulations.

Good to know to be allowed to raise the volume (40l) as quite less for a column speaker.
Looking at the “normal” size of such column (1050x290x350 to 400 deep) I might get about 60 to 70 liters free for the sub.
Winisd shows also a much broader gain.
View attachment 282361

Cabin 70l
Blue: 1 26roy + 2 SL26R + 80 g
Red: 1 W18NX003 - 10 liter

You calculated 40l + SL26R + 200 g for Helmholz resonance 20 Hz, isn’t it?
Doing so with 70l we are at 80g each?

Looking at my notes... I did 80l cabinets with 100g added mass to both of the passive radiators.

Note, despite the sims, these will not play 110dB! You will see large non-linearities in the passives. Not unusual, ports sound bad at high volume too. But the drone cones will tell you when you are exceeding the linear response of the system.

Also it seems that when having the 26roy the cabin sides (left, right) needs more stiffness.
FinkTeam tells us with their new BORG

Test FinkTeam Audio Borg: die neue LowBeats Referenz - LowBeats

An diesem Lautsprecher scheint vieles zuerst außergewöhnlich: Eine Standbox, fernab von gängigen Des

www.lowbeats.de

Cabinet stiffness is important. The forces are rather large. But I am not sure how much improvement can be had over a 'decent' braced cabinet. The biggest deal with the passive radiators is the tendency to rock because of the mass and the low-frequency resonance and excursion of the heavy drones. This is 100% solved by placing them on opposite sides. I used perforated braces inside the cabinet, but I didn't try to engineer special braces around the opening for the passives. That being said, all of my cabinets are ridiculously braced and overbuilt; I wish I spent more time on making them look nice than making them heavier than a neutron star! Some veneer would help too!

Thanks for your sharing your expert thoughts.

By the way:
high will be Mundorf AMT25CS2.1-R
2way active minidsp PWR-ICE250 drives 26roy and Mid/high with passive crossover

Should be fun!

 

[F Jell]

@MAB: thanks for the outstanding comment I go for a 80l enclosure for the ROY.

One question I have still right now
I had a chance to hear a 2way speaker (Mundorf AMT and a 10'' mid/sub - similar to the borg). For me it seems the the AMT is taking over the stage.
As I like to build an old style mid-bass stage column speaker, I'm thinking about having the MID SEAS above the AMT (right arrangement) and not as often seen the AMT on top (left arrangement)

It seems that with the MID on top I lose bass (boxsim simulation). But this seems to be corrected by the dsp. Also the high of the column speaker rises as the AMT is fixed on ear high. But this gives the SUB more liters to 80l, so again a plus.

May you share your thoughts about the arrangement.
Someone told me that MID on TOP (right arrangement) gives the best harmony in such a trio, like KEF does or did in the past. So the AMT will get a little bit into the background of the stage- I hope.

Thank you for your reply.

Also "ente" told me: XM003 SL26R
Qmp (="QMS") = 2 * pi * fp * Mmp / Rmp = 2 * 3,14 * 18 * 0,273 / 4,08 = 7,56

confirmed by SEAS, now

 

[MAB]

@MAB: thanks for the outstanding comment I go for a 80l enclosure for the ROY.

One question I have still right now
I had a chance to hear a 2way speaker (Mundorf AMT and a 10'' mid/sub - similar to the borg). For me it seems the the AMT is taking over the stage.
As I like to build an old style mid-bass stage column speaker, I'm thinking about having the MID SEAS above the AMT (right arrangement) and not as often seen the AMT on top (left arrangement)

View attachment 288593

It seems that with the MID on top I lose bass (boxsim simulation). But this seems to be corrected by the dsp. Also the high of the column speaker rises as the AMT is fixed on ear high. But this gives the SUB more liters to 80l, so again a plus.

May you share your thoughts about the arrangement.
Someone told me that MID on TOP (right arrangement) gives the best harmony in such a trio, like KEF does or did in the past. So the AMT will get a little bit into the background of the stage- I hope.

I'll be honest, I am unfamiliar with the benefit/drawbacks of these M/T/W arrangements. It's a matter of experience not preference, and I don't understand the reasons behind the driver array. But I have heard some that sound great.

Also "ente" told me: XM003 SL26R
Qmp (="QMS") = 2 * pi * fp * Mmp / Rmp = 2 * 3,14 * 18 * 0,273 / 4,08 = 7,56

confirmed by SEAS, now

View attachment 288592

Thanks for the clarification. Vey interesting... Ente told me the same, and the formulae is certainly correct, but he also told me my passive had a RMP of 2.2!
That being said, there are at least two versions of this passive (there are two versions of the L26ROY and two of the L26RO4Y...) In fact two versions of almost every modern driver theny make that I have built with...
The good news is you can tune the things with added mass, like these:

SB Acoustics DW-50 50g Passive Radiator Weight

50 gram Passive Radiator weight for the SB Acoustics 10" SB29RNX-00 passive or 12" SB30NRX-00 passive. Made from Aluminum 70mm in diameter (2.75")4.95mm thick8.2mm hole

www.madisoundspeakerstore.com

I made my own since I have a metal lathe, ended up making a few weights to get things right. Having a few of these per passive is useful. It occurs to me that there aren't tons of good weights available.

 

[F Jell]

@MAB: Hi one short question (I'm coming to the finish line of my concept)
Your 80l cabin with the L26roy and the 2 PM - beside the braces - what did you do further inside.
Did you fill such cabin with Insulation wool/Filling material like SONOFIL white 1 bag

Intertechnik SONOFIL white 1 bag

Kategorie-Übersicht: Sonofil, Accessories

www.intertechnik.com

ore something else.
Thanks for your reply.

 

[MAB]

@MAB: Hi one short question (I'm coming to the finish line of my concept)
Your 80l cabin with the L26roy and the 2 PM - beside the braces - what did you do further inside.
Did you fill such cabin with Insulation wool/Filling material like SONOFIL white 1 bag

Intertechnik SONOFIL white 1 bag

Kategorie-Übersicht: Sonofil, Accessories

www.intertechnik.com

ore something else.
Thanks for your reply.

I used jute fabric, and some standard polyfill (like this).
I have been meaning to experiment and make some measurements. I think Rick Sykora did a study of different fill materials. My main thing is to make sure that the stuffing doesn't get wadded up in the driver's motor and that the internal wiring can't come into contact with anything. The acoustic fill is not the critical thing...

 

[F Jell]

@MAB: I finished a prototype (took a old chest..) so see how the speakers sound together in that placement.
From my point of view it sounds great, never had such clear voices and fat bass together in such harmony - but maybe just luck.
Also 1xL26roy (front) and the 2 PM (side) sound great in 80l as you suggested.
Also the SEAS W18NX003 (top: 120 to 1800 Hz) plays great with the Audaphon amt-1i (top middle) and let the amt-1i not play in the "for-ground".

Here a picture of demo cases for sound test. The front is not ready to correct radiation/baffle step etc..
At the end there will be 1 case for all speakers.

And here my question - as in future 1 case the sub has more liters (about 100l), so I'm thinking of
2xL26roy and 2 PM.
Did you ever try such configuration?

Thanks for your reply and keep in touch

 

[MAB]

@MAB: I finished a prototype (took a old chest..) so see how the speakers sound together in that placement.
From my point of view it sounds great, never had such clear voices and fat bass together in such harmony - but maybe just luck.
Also 1xL26roy (front) and the 2 PM (side) sound great in 80l as you suggested.
Also the SEAS W18NX003 (top: 120 to 1800 Hz) plays great with the Audaphon amt-1i (top middle) and let the amt-1i not play in the "for-ground".
View attachment 305769
Here a picture of demo cases for sound test. The front is not ready to correct radiation/baffle step etc..
At the end there will be 1 case for all speakers.

And here my question - as in future 1 case the sub has more liters (about 100l), so I'm thinking of
2xL26roy and 2 PM.
Did you ever try such configuration?

Thanks for your reply and keep in touch

Fantastic!
I'm sure you have great bass.
The Passive Radiator arrangement you have is optimal. Adding another woofer will increase output a bit, but you will be limited by the PR excursion, (which you could fix by adding two more PR's)
The PR excursion is high at resonance. Most of the extra output of the additional woofer will be limited by the excursion of the radiators. Here is a simulation of 2x L26 radiators in an 80l box vs. 1x radiator in a 40l box:

The radiators will limit the system. You would effectively have two of these 40l 1x woofer and 1x passive. So you don't get the benefit of full-output, if that matters.

Also, this is a simulation, real-world results will be worse due to non-linearities of air and drivers. If you take your present setup and sweep the frequency from 10Hz to 100Hz, you will see the passive radiators large excursion peak just above 20Hz. And, you will see the passives go non-linear way before this box-model predicts!!! (Ports also perform much worse than predicted unless you have a detailed model of the high-velocity air in and around the port). And you will see why it's ideal to put passives on opposing sides of the cabinet, they really move at resonance!

You are really in a pretty sweet spot with the 80l and 1x L26 woofer plus 2x L26 radiator. You can experiment with adding mass to the PRs but this is last tiny optimization. And think about the final cabinets and what might make you happy.