DIY Amphion Bases Prject

[Pablo1980]

Hi, I am going to be making a pair of Amphion Bases type speakers (photo attached), to use with my Amphion One15s, and would like to ask you folks some questions:

1. I am going to be using Seas 10" drivers and passive radiators, there are to options, one with two layers (L26ROY) and one with four layers (L26RO4Y)
Which one would you recommend for this application?

2. I will probably be using two Hypex Fusionamps plate amps, going to choose between FA251 and FA501.
Which would you choose? is 250 watts enough for a single 10" in a large box, working all day with the subs behind the desk? or should I go for 500 watts?

3. Regarding Fusionamp DSP crossover, I want to integrate the One15s and the subs with the crossovers, but be able to bypass the subs and use the One15s in full range mode.
Is this easy to do with the software? I think you can´t control both amps at the same time, so it would be cumbersome to change the usb cable when going full range?


That´s all for now, thanks everybody!

 

[AwesomeSauce2015]

Just a few notes:
1. You're using woofers designed for open-baffle operation in Linkwitz's LX521 speakers. They aren't designed to be used in a tiny closed box... Although they are very good drivers and simulate nicely, I still wouldn't use them in a box like what you attached.
-- If I was designing something like that, I'd personally use 2 shallow mount 10-12" woofers per side (like these: Dayton Audio LS12-44 [other sizes are available] ), and do a ported alignment. Those drivers I linked are designed to run in small, ported enclosures, and will probably be better than the seas woofers in your application.

2. The power will be determined by the box dimensions and woofer parameters. Chances are, if you are using it as a subwoofer, then you will be excursion limited down low, and won't be able to use even 250w of power. However, I will also say that the woofer you mention is designed for open baffle use. Putting it in a small box with a passive radiator is kinda the opposite of the designed use case...
-- You can simulate subwoofer boxes with something like WinISD. It can simulate the driver's excursion at various power levels given the box and woofer parameters.

3. I don't have experience with hypex's software, so can't help there. What you may want to do is get a MiniDSP or something similar which can hold 2 presets, that you can switch between with a remote or something. Then you can get less expensive non-DSP amps for the subs.

Also: Do you have a link to someone else who has built what you're talking about? Just curious to know if anyone else has built a tiny sub with the linkwitz woofers...

 

[Wolf]

No, the original ROY was not designed for the LX521. Linkwitz noticed it and had one adapted for his specific usage. The other newer model is meant for free air.

 

[Pablo1980]

Just a few notes:
1. You're using woofers designed for open-baffle operation in Linkwitz's LX521 speakers. They aren't designed to be used in a tiny closed box... Although they are very good drivers and simulate nicely, I still wouldn't use them in a box like what you attached.
-- If I was designing something like that, I'd personally use 2 shallow mount 10-12" woofers per side (like these: Dayton Audio LS12-44 [other sizes are available] ), and do a ported alignment. Those drivers I linked are designed to run in small, ported enclosures, and will probably be better than the seas woofers in your application.

2. The power will be determined by the box dimensions and woofer parameters. Chances are, if you are using it as a subwoofer, then you will be excursion limited down low, and won't be able to use even 250w of power. However, I will also say that the woofer you mention is designed for open baffle use. Putting it in a small box with a passive radiator is kinda the opposite of the designed use case...
-- You can simulate subwoofer boxes with something like WinISD. It can simulate the driver's excursion at various power levels given the box and woofer parameters.

3. I don't have experience with hypex's software, so can't help there. What you may want to do is get a MiniDSP or something similar which can hold 2 presets, that you can switch between with a remote or something. Then you can get less expensive non-DSP amps for the subs.

Also: Do you have a link to someone else who has built what you're talking about? Just curious to know if anyone else has built a tiny sub with the linkwitz woofers...

I will look for the threads of some folks using those drivers to emulate the amphion bases

It could be internet myth by I have read in several places that Amphion used those in the baseone25s:

From the original release thread in gearspace:
BaseOne25’s SEAS 25 cm (10”) woofer and 25 cm passive radiator array are mounted in a beautifully crafted enclosure measuring 1020mm x 191mm x 355mm (40”x 7.5”x 14”).

Besides that, there is an pdf in the SEAS page that shows how the new ones can be used in a closed box with a passive radiator:
http://www.seas.no/images/stories/design/pdf_datasheet/L26ROY_Application_Note.pdf

About the minidsp, I have read that they can be a bit noisy, is that true?

No, the original ROY was not designed for the LX521. Linkwitz noticed it and had one adapted for his specific usage. The other newer model is meant for free air.

So the new XM004 and XM001 that are made in Norway are indeed for free air? (I don´t think I can buy the older ones).
Everyone that sells the new ones pair them with the passive radiator.

 

[NTK]

No experience with the Hypex Filter Design software or the Fusion amps.

However, from glancing the HFD manual, I think you can setup one preset that has a high-pass filter for the main speakers, and another preset without. Use the preset with the high-pass filter in combination with the subs' low pass filter when you are using the subs. Switch off the subs and use the other preset when you are not using subs.

 

[AwesomeSauce2015]

No, the original ROY was not designed for the LX521. Linkwitz noticed it and had one adapted for his specific usage. The other newer model is meant for free air.

Huh. I didn't know that. Interesting.
Either way, I still stand behind what I said. Get subs designed for mounting in shallow enclosures, and go from there.

I simulated 2 of the woofer I mentioned above, in the box dimensions you listed above (40x7.5x14=2.43cu-ft), with a port tuned to 25hz, and a few filters to smooth out the response and a high pass filter to keep the excursion in check under tuning frequency.
I have a -3db point of 30hz, at about 112db, but that's with 250w of input power + a 6db filter boost. That means 250w*(2^[6db/3db]) = 250w*4 = 1000w. Per side, and only for peaks because the drivers are only rated for 250w RMS each.

But your needs and design goals may be different, so you really should play around with winISD for yourself before buying anything.

 

[jhaider]

Don’t the current Amphion bass bins use SB Acoustics shallow woofers? Why not start there? Those are really excellent drive units for tiny equalized closed boxes.

 

[Pablo1980]

Don’t the current Amphion bass bins use SB Acoustics shallow woofers? Why not start there? Those are really excellent drive units for tiny equalized closed boxes.

That´s a great find thanks
So they use two of them in a dipole arrangement, and dual 900watts amp.

Do you think I could use a single SB driver with a passive radiator, or would I need two per cabinet as the current Amphion ones?

 

[Wolf]

I think some of you misunderstand me about new and old L26ROY.

The original L26 had a different frame structure, and it is now NLA, and was never infended for free air use. The replacement has a new in house made frame, and is the X1001/L26ROY. It is not meant for free air use.

The XM004-04S/L26RO4Y, is meant for the LX521/Orion designs and free air use. It also uses the newer frame. Linkwitz worked with Seas to develop this version for his design, just like he did the L16-SL version for the LXmini.

 

[Pablo1980]

Thanks for the info!

They are very heavy and difficult to import so I am leaning toward the Sw26 shallow subwoofers drivers Jay mentioned, which are used in the current Amphion bases.

If you think I could use one driver and a passive radiator in that kind if enclosure (as the one in the photo) I think I will go ahead.

Won’t be using plate amp finally, what amp modules do you think I should use for this kind of music production use with no very high spl?

 

[jhaider]

That´s a great find thanks
So they use two of them in a dipole arrangement, and dual 900watts amp.

Do you think I could use a single SB driver with a passive radiator, or would I need two per cabinet as the current Amphion ones?

It looks like they use 2 woofers and 2 passive radiators. I’m not sure those PRs are available to DIYers, and a different PR would look weird with that distinctive woofer. If you have EQ you could use two of the woofers dual opposed in a slim closed box per side. PRs will add efficiency over a small bandwidth, but usually aren’t much cheaper than full drivers.

Two other great options are Peerless XLS and ScanSpeak Discovery. I’m sure Seas are fine too - I’ve never personally used them. But the SB is probably the best current woofer for a tiny closed box, unless you happen upon NOS Peerless XLS drivers - I don’t think their current ones have the super strong motors of the OGs.

 

[Pablo1980]

They sell the passive radiators, less than half price than the driver. (Black ones, as the diy drivers)

I don’t think I can afford four drivers and four PR so I could go with the old configuration of a driver and the PR on the same side of the box

 

[jhaider]

I’d spend the extra for two real woofers. The benefits are more broadband SPL and greater stability (if they’re dual opposed) - you don’t want the subs rocking under the mains.

 

[Pablo1980]

Ouch. I would need 2 drivers and 2 PRs for each base? (With import duties it would be more than 2000k just for those parts)

Or with the two woofers I can discard the PR?

(The first amphion bases had one Seas L26roy and a passive radiator on one side and they work very well, my doubt is what would happen with the sallow sb drivers)

 

[jhaider]

Ouch. I would need 2 drivers and 2 PRs for each base? (With import duties it would be more than 2000k just for those parts)

Or with the two woofers I can discard the PR?

(

I would skip the PRs.

 

[Juhazi]

I have used SEAS L26ROY, SB29NRX and SS Discovery W21 in sealed boxes, active with minidsp and Hypex FA123. All are fine even as woofers 20-500Hz, sub task is easier.

Two per speaker SB29NRX75-8 parallel, sealed, woud be my choice for you (the number tells the diameter of the frame, the membrane is much smaller). Four per speaker, if you want to wear ear protection and work in a building alone.

125W nominal power of FA123 can easily make these to bottom with modest EQ, so no need for more power, but every other model has more power. Yes, you have four presets and you can attach remote module, but each unit must be controlled individually. Digital signal can be chained. I use analog.

ps. I have a pair of Amphion Helium2 with foam plugs https://www.stereophile.com/standloudspeakers/105amphion/index.html

 

[MAB]

1. I am going to be using Seas 10" drivers and passive radiators, there are to options, one with two layers (L26ROY) and one with four layers (L26RO4Y)
Which one would you recommend for this application?

I recommend the L26ROY, although the L26R04Y will work as well. I don't have experience with the SB Acoustics subs, but they do look wonderful. I do have experience with both the L26ROY and the L26RO4Y and the SL26R passive radiator, I built four subwoofers with a single L26ROY and two SL26R radiators per sub. They are great.
There is an application note from Seas on the build:

http://www.seas.no/images/stories/design/pdf_datasheet/L26ROY_Application_Note.pdf

Ideally, you do want twice the passive radiator are as the active drive unit. This is because the excursion of the passive radiator at resonance is quite large for a single radiator of equal size (same reason a port moves so much air on resonance). A single L26ROY and two Seas SL26R in a 40 liter box is optimal, this configuration requires 200g of added mass per radiator (there is a screw on the back of passives to adjust the mass). The other advantage is that you can mount the radiators on opposite sides of the box and reduce (actually nearly eliminate) the rocking effect. The subs I built with opposed radiators are dead stable, no rocking or crawling across the floor. The cabinets feel vibration free if you put your hand on them at high volume, it is quite dramatic. I have another pair of Seas subs with single passive radiators in 100 pound cabinets, and they do rock and creep on a smooth floor and you can feel the cabinet vibrate at high volume. And, if you play just the subwoofers, the one with the single passives make lots of noises at high excursion that the duals are silent; part of this is the excursion but part of it is the cabinet tap-dancing like a phone on vibrate... Force cancelling = good.

The project you plan to do sounds like tons of fun, and should work with a range of drivers. If I was going to use passive radiators, I would use two opposed no matter which vendor you go with since it is optimal for excursion and for vibration.

 

[MAB]

I would skip the PRs.

Yes, this would be a great option as well. Two active subs in a sealed box with EQ vs. a single sub plus two passive radiators... The cost of two radiators is typically about the same as a single sub. Both are going to be awesome. Perhaps the dual sealed is the way to got as jhaider suggests.

 

[Pablo1980]

Thanks everybody for your knowledge !

So, lot to think about, I think the seas x2 drivers per box will go beyond my budget. I could do two SB per box.

it would be different from the amphion design which I heard and love (they do a stereo central base with two Seas, though)

The price of the amp will be a determining factor, what’s the consensus about power for this bases?

 

[Juhazi]

A single SB29NRX75-6 sealed in-room responses and nearfield. Sorry, I don't have high spl tests of this. A sealed sub often has very smooth room response because of low freq gain from floor and wall boundaries.