Magico Owners and Discussion Thread

[almikel]

2 minutes ago, Ittaku said:

Yes they do interest me but my room just won't fit them no matter how much I want them to

bummer - so you have no options for infinite baffle? (roof space, underfloor, garage, spare room, outside etc etc)

For delivering <20Hz they're such a simple concept.

[davewantsmoore]

53 minutes ago, almikel said:

So the Rotary Sub has no appeal?

 

I would stick with ~10Hz and up

 

Edited November 29, 2018 by davewantsmoore

[almikel]

14 minutes ago, davewantsmoore said:

 

I would stick with ~10Hz and up

 

whatever you posted didn't work

15 minutes ago, davewantsmoore said:

would stick with ~10Hz and up

I'm ok with a reasonably flat to 20Hz and rolling off below 15Hz response in my leaky small room with a DIY tapped horn.

@Ittaku is looking for premium bass sub 20Hz (I think?) - Every direct radiator will run out of puff below 20Hz, and horns get too big (including tapped horns).

The Rotary Sub, if you have the option for an infinite baffle install, is ideal for <20Hz...

 

was your post something to do with the house falling down with infrasonic bass?

 

Mike

[davewantsmoore]

2 minutes ago, almikel said:

whatever you posted didn't work

I fixed it.   @#$ dropbox.

[almikel]

5 minutes ago, almikel said:

was your post something to do with the house falling down with infrasonic bass?

 

3 minutes ago, davewantsmoore said:

I fixed it.   @#$ dropbox.

thought so

 

[davewantsmoore]

3 minutes ago, almikel said:

Every direct radiator will run out of puff below 20Hz

Most well above .... I don't see how 20Hz is any sort of magic barrier though.   You just need more Vd.

 

3 minutes ago, almikel said:

and horns get too big (including tapped horns).

The subwoofer drivers I use have Fs=18Hz .... and I've been simulating tapped 'horns' for them for ages, wondering if I should ever build one .... but 4m long (floor-ceiling-floor) isn't really big enough   0_o

 

3 minutes ago, almikel said:

Was your post something to do with the house falling down with infrasonic bass?

Yep.   There's lots of comical ('cos it isn't me) posts from years gone by at cult of infinitely baffled or HTShack .... where people post pictures of their cracked foundations, and the like.

[Ittaku]

19 minutes ago, almikel said:

 

@Ittaku is looking for premium bass sub 20Hz (I think?) - Every direct radiator will run out of puff below 20Hz, and horns get too big (including tapped horns).

The Rotary Sub, if you have the option for an infinite baffle install, is ideal for <20Hz...

No, I'm actually looking for something for the last octave 20-40Hz, and then some infrabass. My main speakers go to 30Hz, but I'd like to offload them to do 40+ only to optimise their sound quality and use a sub to fill in below that. My current sub does 35 and below, and the reason I don't use 40 is the quality of sound from the sub is clearly inferior to that of my main drivers, even though the sub's bass is very good below that. Ported is completely out of the question as it's almost impossible to make it sound seamless going to a high power low extension open baffle driver as I currently have. So basically I just need loads of driver area, loads of excursion and loads of power.

[davewantsmoore]

16 hours ago, Ittaku said:

No, I'm actually looking for something for the last octave 20-40Hz, and then some infrabass.

DIY is out of the question?

[Ittaku]

2 minutes ago, davewantsmoore said:

DIY is out of the question?

I most certainly have not ruled it out, but I'm still working on finalising my main baffles... these things always happen slower than I'd like them to

[almikel]

@Ittaku, can you remind us what your current sub is?

 

3 hours ago, davewantsmoore said:

DIY is out of the question?

IMO subs are the easiest speaker to DIY with a high probability of an excellent outcome.

 

Integration is of course a challenge - but that's the same whether the sub is bought or DIY'd - and the DIY approach gives a lot of flexibility with crossovers, DSP, box form factor etc

20 hours ago, Ittaku said:

So basically I just need loads of driver area, loads of excursion and loads of power.

agreed - the 18" drivers being discussed over in @Primare Knob's thread - Dayton UM18-22 and RSS460HO would provide a good basis for a sub or subs - obviously there are loads of options.

 

PK's been discussing dual opposed subs. 2 subs (4x18" drivers) with appropriate amplification would satisfy most.

The dual opposed design appeals to me to reduce cabinet vibrations.

Add EQ and enough power and you can build them pretty small.

 

cheers

Mike

 

 

[davewantsmoore]

4 minutes ago, almikel said:

The dual opposed design appeals to me to reduce cabinet vibrations.

Seems to work a lot better in theory than practise   

 

If the motors have significant non-linearity ... you can arrange the drivers to cancel that, but it's much harder to arrange .... and it's just better to keep the excursion down, if that's an option.

[Primare Knob]

Seems to work a lot better in theory than practise  [emoji6] 
 
If the motors have significant non-linearity ... you can arrange the drivers to cancel that, but it's much harder to arrange .... and it's just better to keep the excursion down, if that's an option.

In my understanding in this is that you need the drivers to be very close to each other, nearly touching. The number of shortening rings can improve linearity and this might make this benifit no longer a benifit.

[almikel]

13 minutes ago, almikel said:

The dual opposed design appeals to me to reduce cabinet vibrations

 

2 minutes ago, davewantsmoore said:

Seems to work a lot better in theory than practise 

My T20 tapped horn is built as dual opposed, and the cabinet is quite inert even though it's just 19mm formply.

 

4 minutes ago, davewantsmoore said:

If the motors have significant non-linearity ... you can arrange the drivers to cancel that, but it's much harder to arrange

agreed - I haven't done that (reverse a driver orientation to attempt to reduce that type of distortion)

6 minutes ago, davewantsmoore said:

and it's just better to keep the excursion down, if that's an option

agreed - which can be a challenge with sealed boxes going low, but multiple 18"s (whether dual opposed or single driver boxes) shouldn't need to move "that" much at "reasonable" SPLs depending on @Ittaku's low frequency and SPL targets...???

...although it was @Paul Spencer's blog post on 2 x Rythmik 12" subs in sealed vs tapped horn enclosures that convinced me to build my T20 tapped horn - I haven't regretted it.

http://redspade-audio.blogspot.com/2012/02/how-does-sensitivity-of-tapped-horns.html

 

My T20 has ample LF extension in my room with 2 x 12" drivers at good SPL with ~750W - you just need the room to fit in a big box (2400x300x400mm) - or mount it outside the room

 

Many ways to skin the cat, but you end up back at Hoffman's Iron Law - but lots of cone radiating area and lots of power while keeping excursion low is the key.

 

cheers

Mike 

 

[acg]

54 minutes ago, davewantsmoore said:

and it's just better to keep the excursion down, if that's an option.

I know when I was testing for the build of my Bass Cannons with their over-engineered barrels that the difference between sub-millimetre excursion and even 5mm was very noticeable if the box was not very rigid and inert...the pistonic power of those lightweight cones is quite extraordinary. 

 

The boxes being talked about in this thread will likely have much larger excursion than my solution so resonances will need to be well controlled in very rigid and inert boxes because the only way to reduce excursion is to increase driver cone area and it seems as though enormous subs are not going to be suitable in this instance. 

[davewantsmoore]

9 minutes ago, almikel said:

My T20 tapped horn is built as dual opposed

Sure, but how else could you fold the horn?!   

 

What I mean is that there is less benefit than you might imagine.

 

9 minutes ago, almikel said:

Many ways to skin the cat

Well, definitely building a tapped pipe, if you have the space and don't need to go super-super low ..... is the best way to keep excursion down and output up, by a big margin.

[Primare Knob]

The biggest problem I find is that with dual driver subs, the amplifier power required doubles, and big amplifier output is more easily distorted, and to find out by how much and when, you will need to be able to find and understand the specs. Something @davewantmore seems to have a lot of experience in.

You can increase efficiency by designing a larger box that does require less power, but this has a big influence on how quickly the driver passed xMax when the frequency goes down.

I think there are enough drivers that can go very low in a clean way. At this point in time, I am not sure if there are any ready available amplifiers that can produce the required clean power needed to drive them.

I haven't read the whole thread so I don't know your requirements. I just started the DIY experience myself and still need to put it into practice.

[davewantsmoore]

5 minutes ago, acg said:

if the box was not very rigid and inert

The box needs to be well braced, so that as much of the outer walls are supported (and held still)... and ideally made out of something with relatively good internal damping.

 

[davewantsmoore]

2 minutes ago, Primare Knob said:

You can increase efficiency by designing a larger box that does require less power, but this has a big influence on how quickly the driver passed xMax when the frequency goes down.

Don't mix up cause and effect here.

 

Increasing the box makes the woofer more efficiency at low frequencies .... which means for the same power input, it will now exceed xmax earlier at lower frequencies .... but this just means it's producing more (ie. too much) SPL at low frequencies.

 

... it's up to you to filter the woofer so this doesn't happen.

2 minutes ago, Primare Knob said:

I think there are enough drivers that can go very low in a clean way. At this point in time, I am not sure if there are any ready available amplifiers that can produce the required clean power needed to drive them.

Sure there are 1, 2, and more kw amplifiers which will do just great, if you need that much power.

[Ittaku]

28 minutes ago, davewantsmoore said:

Sure there are 1, 2, and more kw amplifiers which will do just great, if you need that much power.

My current sub is a 1.5kW RMS, 5kW peak amp, so that's the target to match/beat.

[Satanica]

54 minutes ago, Ittaku said:

My current sub is a 1.5kW RMS, 5kW peak amp, so that's the target to match/beat.

But what if there's a better subwoofer that happens to have a less powerful amp, no good?

[davewantsmoore]

48 minutes ago, Ittaku said:

My current sub is a 1.5kW RMS, 5kW peak amp, so that's the target to match/beat.

IMHO, ideally you would have a subwoofer(s) which did not require that much input power....  but that will require space.

[davewantsmoore]

3 minutes ago, Satanica said:

But what if there's a better subwoofer that happens to have a less powerful amp, no good?

Exactly.   4x 18" drivers in 1000L only needs a few hundred watts to make ~110dB @ 10Hz .... double or triple that depending on the driver ..... but it's 1kw peak.    Obviously, that's a large box, but.

[Pops110]

@Ittaku this looks pretty interesting.

 

https://www.yg-acoustics.com/product/invincible

Edited February 21, 2019 by Pops110

[Ittaku]

1 minute ago, Pops110 said:

@Ittaku this looks pretty interesting.

 

https://www.yg-acoustics.com/product/invincible

Yes that looks quite sexy!

[Pops110]

Bit pricey too. 100k us.