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Old 2nd January 2010, 02:38 AM   #21
jwmbro is offline jwmbro  United States
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Quote:
Originally Posted by TheSeekerr View Post
If you come back down from 15" drivers to 12"', you'll find that the Exodus Shiva-X2 can be built in a ported enclosure as small as 70 litres. Shiva-X2 Application Notes - Home Theater Systems - Electronics and Forum - HomeTheaterShack
Thanks for that tip, it models really nicely, however it's a bit on the pricey side, and not entirely easy to find around here.

But silly me, I spent so much time looking at the Dayton DVC-385 15", I didn't look at the DVC-310 12" little brother at all.

Apart from lower power handling and xmax, it does appear to be rather similar to the Shiva X-2, apart from 2Hz higher F3 in this application:

Click the image to open in full size.
(pic is with subsonic 24dB filter)

Seems to work quite nicely in a 85l vented box (my size limit) and a 24Hz -3dB point is quite nice in my opinion.

At 139$ from PE, that's just under 100€, and I think I could get it over here for an additional 50 euros. Add 250 for this amp and I'm only over my budget by the material cost.


arande2, I also looked at the XLS/XXLS, but not sure they're what I'm after.... will look at the Seas link tomorrow as well, thanks The golden mean.

Meanwhile, any opinions on the 85 liter box with the Dayton 12"?
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Old 3rd January 2010, 07:11 PM   #22
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The Reckhorn amp is probably a good product. For the project for my friend we will go for
the XTZ amp tested in Klang+Ton 4/2009. It would have been interesting to compare the two amps but Reckhorn isn´t being sold in our country I believe.

Resultat av Googles bildsökning efter http://www.mindaudio.de/picture/kundenpics/Sheet_SubAmp1/SubAmp1_panel_detail.jpg
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Old 3rd January 2010, 09:46 PM   #23
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Have a look at the maximum SPL graph, that's where the differences between these drivers will show up. You should find that the maximum SPL at F3 of the Shiva is much higher than the Dayton.

That said, the Dayton is still a good driver, and much cheaper.

The cheapest place to get the exodus gear in Europe is (usually, depending on the exchange rate) at Shiva-X2 12" , prices are inclusive of shipping.
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Old 3rd January 2010, 11:37 PM   #24
jwmbro is offline jwmbro  United States
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Quote:
Originally Posted by The golden mean View Post
The Reckhorn amp is probably a good product. For the project for my friend we will go for
the XTZ amp tested in Klang+Ton 4/2009. It would have been interesting to compare the two amps but Reckhorn isn´t being sold in our country I believe.
Hello,
it's a bit hard to find much feedback on either amp, I did find a little bit on the Reckhorn, though some of it was for older versions (400-402). Some criticisms, but most of them seem to be issues that have been rectified or are easily rectified. Germany offers a 14 day return law for online purchases, so should I be somehow discontent I can utilize that.

It's nearly impossible to find any mention of "sound quality", but I assume when you're looking at the amp of the woofer, there's not too much effect on the total tonal quality of your system.

In fact, an idea I had was to just build the enclosure with driver, and amplify it with one of the rear surround channels on my 7 ch amp. the input signal would already be highpassed, and I did some checks with WinISD Pro, 60Watts of amplification would keep the excursion below xmax, even in the subsonic range without a low cut, and would still go plenty loud enough for my taste.

Quote:
Originally Posted by TheSeekerr View Post
Have a look at the maximum SPL graph, that's where the differences between these drivers will show up. You should find that the maximum SPL at F3 of the Shiva is much higher than the Dayton.

That said, the Dayton is still a good driver, and much cheaper.

The cheapest place to get the exodus gear in Europe is (usually, depending on the exchange rate) at Shiva-X2 12" , prices are inclusive of shipping.
Thanks, that is rather pricey. Thanks for the info about SPL, but I think that's not something I need to be worried about, seeing as I'll be using this in a 24 m^3 (yes, that's a 3!) room at first.

On a slightly unrelated note - the fact that parts-express.com has been unreachable for nearly a week now is quite annoying, and hinders my research a bit.
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Old 4th January 2010, 12:26 AM   #25
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Originally Posted by klankymen View Post
In fact, an idea I had was to just build the enclosure with driver, and amplify it with one of the rear surround channels on my 7 ch amp. the input signal would already be highpassed, and I did some checks with WinISD Pro, 60Watts of amplification would keep the excursion below xmax, even in the subsonic range without a low cut, and would still go plenty loud enough for my taste.
If its not too expensive, I'd go with a big amp for the sub, music with a higher peak-to-RMS ratio than sinewave (only 3dB) require more headroom. The point is not to blast 500W or whatever continuously when playing loud, but to avoid clipping due to voltage (or possibly current) limiting at the amplifier.

If you're curious about Peerless XLS/XXLS performance, here are measurements of one 85L ported XLS 12" DIY Peerless XLS 12" ported 85L - Home Theater Systems - Electronics and Forum - HomeTheaterShack

That's very solid distortion performance, among the very best and ultimately limited by the amplifier in this case.

This smaller passive radiator build fares well too until the even smaller amp runs out of gas: DIY Chorus XP3 clone - Home Theater Systems - Electronics and Forum - HomeTheaterShack

If you can source the Dayton RSS-series drivers, they are very good performers too. Diymobilaudio forum hosts some Klippel tests of drivers, here's a test of the 12" Dayton RSS315HF: DIY Mobile Audio

I would expect that Dayton to perform as well as the XLS/XXLS-line from Peerless.

I recently measured my Dayton RSS390HF in a similar (but not exactly the same) manner to the above HTShack tests. I used a very small sealed box which requires external EQ for good in-room balance, but distortion performance per SPL remains quite good; a testament to the good design of the RSS-series.

A larger box would allow less steep roll-off, but I think on balance those 12" ported/PR builds based on RSS, XLS or Shiva-X are better with box sizes in the 80L range.
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Old 4th January 2010, 12:35 PM   #26
jwmbro is offline jwmbro  United States
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Originally Posted by breez View Post
If its not too expensive, I'd go with a big amp for the sub, music with a higher peak-to-RMS ratio than sinewave (only 3dB) require more headroom. The point is not to blast 500W or whatever continuously when playing loud, but to avoid clipping due to voltage (or possibly current) limiting at the amplifier.
How big is big? My mention of the 60Watts of amplification was just sort of as a stop-gap, temporary measure, to get an idea of the extended frequency range of a subwoofer, before I buy a proper sub amp. The reckhorn is rated at 290W into 4Ω, though I could probably even find a more powerful amp.

However, I once read that it's recommended to have an amp with less power than the driver's Pe, so that you don't push more power into the driver than it can handle. Or am I confusing something here? It was a while ago that I read that.

Quote:
Originally Posted by breez View Post
If you're curious about Peerless XLS/XXLS performance, here are measurements of one 85L ported XLS 12" DIY Peerless XLS 12" ported 85L - Home Theater Systems - Electronics and Forum - HomeTheaterShack

That's very solid distortion performance, among the very best and ultimately limited by the amplifier in this case.

This smaller passive radiator build fares well too until the even smaller amp runs out of gas: DIY Chorus XP3 clone - Home Theater Systems - Electronics and Forum - HomeTheaterShack
Thanks for the HTS links, it seems to be a good resource.

Quote:
Originally Posted by breez View Post
If you can source the Dayton RSS-series drivers, they are very good performers too. Diymobilaudio forum hosts some Klippel tests of drivers, here's a test of the 12" Dayton RSS315HF: DIY Mobile Audio

I would expect that Dayton to perform as well as the XLS/XXLS-line from Peerless.
They are a bit more expensive to ship due to their higher weight, but I should be able to get ahold of them as well. I was recently reading about the RSS315, because Zaph designed a sub using that, which is a pretty good recommendation in itself for me.

I unfortunately can't view the link, because it wants me to sign up / log in first - is the data worth registering for? I'm a bit reluctant to sign up to a ton of places...

Quote:
Originally Posted by breez View Post
A larger box would allow less steep roll-off, but I think on balance those 12" ported/PR builds based on RSS, XLS or Shiva-X are better with box sizes in the 80L range.
That's relieving, cause I can't fit anything larger than 90L or so

I think I've discovered a few good drivers / designs already, not too easy to chose one. However I'm definitely still going to do some more research before I build - hopefully I will find something so good that the choice is made easy


One question: It seems like most sub amps have a subsonic lowcut filter, which is necessary for vented designs. Are there also amps without that filter? It seems to me that it would be quite unnecessary in a sealed design, and would only add group delay but no real benefit - is that correct?

I was pretty set on building a vented sub based on the WinISD models, but having seen some in room response curves of sealed subs, and also what can be done with EQ and linkwitz circuits, I'm not so sure anymore...

Last edited by jwmbro; 4th January 2010 at 12:38 PM.
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Old 4th January 2010, 01:01 PM   #27
AndrewT is offline AndrewT  Scotland
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if you want to get the maximum clean (unclipped) SPL from a speaker it seems to be generally advised to use an amplifier that is capable of delivering double the power rating of the speaker.

For domestic listening this max SPL requirement is nonsense.

I modified a B950 by doubling the mass of the cones, thus reducing the sensitivity by 6dB and retuning the ports down by half an octave.
The speaker now does 95dB/2.83V @ 1m and is rated for amplifiers between 1000W into 4ohms to 2000W into 4ohms.
I am using just 340W into 4ohms and it produces generous bass, that sounds just right for all programme material, with just a few tenths of a watt driving it.
The amp and speaker have a +30dB transient capability if something louder comes along at those low frequencies.
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Old 4th January 2010, 07:22 PM   #28
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The ratio of amp power to speaker power is debatable. Too little amp power, it clips, speaker dies due to excess square waves, resulting in extra (free, in the form of short-term DC) power being shoved in.
At roughly 1:1, the speaker hits mechanical limits as the amp starts to clip - very nasty sound very quickly.
More (significantly more) power from the amp means the speaker will go into mechanical damage, and the voicecoil will need replacement due to it hitting the backplate. This would only happen when excursion becomes an issue. For mids/highs, it's probably best to use too much power.

IMO, see what you can get hold of, make sure the price is right. But make sure it is ENOUGH power - you don't want the amp to clip at 90dB.

Chris
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Old 1st February 2010, 09:31 AM   #29
jwmbro is offline jwmbro  United States
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Well, I'm back with a concept. I'd been thinking about doing dual Dayton RSS315HFs in 60 liter cubes (each external edge 450 mm / 18 inches long). However, seeing as I have a very small room (10 square meters / 110 square feet), two concerns need to be addressed. One is obvious: lack of space. I'd like to have as small a footprint as possible, and each of those boxes would eat away 0.2 square meters of my precious 10. The other concern is room modes and standing waves. The reason I've been looking at dual subs is not for more output, but rather because I heard placing 2 subs at opposite ends of the room helps alleviate room modes.

So, I had an idea, which would kill two birds with one stone. Introducing... The Monolith:

Click the image to open in full size.

What do you think? It's basically two 60 liter subs in one enclosure (separated from each other by an MDF divider). Its external footprint is a mere 190mm x 420mm (7.5" x 16.5") and it's 2.4m tall (8ft), meaning it would span the entire height of the room, placing one driver near the floor, and one near the ceiling.

Here's a few more schematics I made:
Front view:
Click the image to open in full size.

Top view:
Click the image to open in full size.

Side view:
Click the image to open in full size.

3D view:
(one thing not visible on the 3d view yet, which I just added, is that I decided the divider between the 2 compartments should be sturdier - brace construction shamelessly stolen from Zaph)
(also, the z-axis placement of the braces is far from decided, in fact I just put them in randomly in sketch-up - in a final build the plan would be to have them spaced at indivisible distances, or perhaps multiples of the golden ratio, as to minimize vibrations)
Click the image to open in full size.

The construction I'm imagining would be quite simple, using mainly 19mm thick MDF, just (4) 8-foot-long rectangles to make the sides of a long box, and (9) little 142mm x 382mm rectangles would serve as the floor, ceiling, divider and braces of the box.
Add in an 8ft long piece of 10mm thick solid wood or plywood glued to the front, serving both the purpose of making it look better, and eliminating the need to recess the drivers. And it would hold the magnets for attaching the grilles (a simple canvas spanned pine-beam frame)

Amplification would be external of course, with dual terminals to allow for series / parallel / "bi-amping" connection.

As you can see, it would have metal L-joiners (not sure what the proper term for these is) attached to the side, to mount it to the wall to keep from falling over (when the bass is booming ). Between the box and the wall/floor would be slabs of rubber/bitumen "washing machine decoupling mats", which are available cheaply at home improvement stores.

No worries about the wall rattling, by the way, as it's a solid concrete behemoth which is very rigid and solid even by thorough German construction standards.

So, what do you think? I've spent some time thinking this through, but I can't really catch issues of which I'm not aware that they exist.
Does this look like a good idea? I rather like the thought of it, because it would be nice and unobtrusive I think (despite it's rather massive size). Am I missing something?
Any feedback is appreciated, Thank you.

Last edited by jwmbro; 1st February 2010 at 09:34 AM.
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Old 1st February 2010, 07:43 PM   #30
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When it comes to flexability two separate enclosures is better I think. You can calculare the modes for your small room and in some way predict the best place to locate them. You probably know of programs like Cara. But moving them around some is as I see it the final touch. There is the possibility that let´s say four smaller subs would give an even better end result but then we have a more complex solution.

I´ve seen mesurments for six subs placed differently in one room and some may say when it comes to so many there is only the option of placeing them in a random way.

I´do not doubt that your plan will work. But there are the rather large areas of the front and back panel. They are at risk of vibrating. The bracing and the tight connection of the back panel to the wall may cure this but I would like to see some combinations of different materials because the different properties of materials can aid in rejecting vibrations (we may call it acoustic impedances). It can be as "easy" as bonding MDF and particle board together, or more advanced; granite and plywood or slate and plywood. Braces in different directions and in a more irregular pattern is what I have used. I believe modern CAD programs may fool us to make nice and symmetrical drawings but this may not be the best approach in the real world.
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