Oops! Now what?

[cytokine]

I won an ebay auction for a PartsExpress 500W subwoofer plate amp.

I put in the bid not expecting to win this auction.

I had been planning to build something small and tight to go with a pair of Zaph designed MTMs that I'm building.

The NHT 1259 was the driver of choice for that build and I may still end up using it even though this amp will have way too much headroom.

I guess I have a lot more options now, for example I could build something big and tight.

The main thing I want out of this build is something that will be musical and really quick in the transients and that will integrate well with my two-channel music-only system.

Suggestions?

 

[Cal Weldon]

The only "really quick" sound I know is PA stuff. How big of a driver are you planning?

Cal

 

[cytokine]

Hi Cal;

I wasn't "planning" in the traditional sense .

I was "surfing" and came across the plate amp and saw the current high bid, put in something to top it that was still a significant savings over new, and won.

Now I'm sort of backing and filling trying to figure out what to mate with it for the two-channel rig.

You replied to my previous thread and with your help and that of others who responded I decided on a single sub rather than trying for stereo.

After quite a bit of research I had just settled on the NHT 1259 and a 250W plate when this happened.

So now I'm thinking I could go 15" if it will sound really musical. Otherwise I'll stick with a 12".

I like what I've read about the AE AV15 (and the AV12). I'm pretty sure that the Selenium Pro driver you recommended won't work because it's an 8 ohm load. I also can't feature why it would be a good subwoofer in a sealed enclosure with such a high Fs. I truly don't know much but I do know lower is better.

I know simon5 will advocate the AE drivers. Can I do better than the 15" for $180?

I have some time to work this out because the amp doesn't arrive for a while and the drivers for the MTMs are back-ordered at Madisound until Sept 15th.

Any and all suggestions for a musical sub for a two channel rig will be appreciated.

 

[Cal Weldon]

Originally posted by cytokine [B
I'm pretty sure that the Selenium Pro driver you recommended won't work because it's an 8 ohm load. [/B]

I don't understand.

I also can't feature why it would be a good subwoofer in a sealed enclosure with such a high Fs. [/B]

I agree it's not a sub. It's just called that. (A sore point with me by the way. I don't believe it should be called a sub unless the Fs is 20Hz or lower) Rather it delivers bass in the PA way. It pounds itself into you with high dB, very litlle flubber and doesn't worry too much about the really low end. Great for music, perhaps not as suited to HT.

Cal

 

[cytokine]

Power handling of the driver is 800W. The plate amp is 500W into 4 ohm, ~250 into 8 ohm. That would be under-utilization of both pieces of equipment.

So it isn't a sub after all... As far as delivering bass the PA way, my feelings about that are mixed. I don't think of PA bass as being wonderful yet at the same time the last stadium show I went to was Santana a few years ago and my wife's comment was that the bass hit you in the chest. Sort of knocked the wind out of her for a moment. Is that what this driver does?

Will it work with that plate amp in the way I described above? Is it the one you have, and do you swear by it ?

 

[rcw]

re bass

The bass that resonates the chest cavity is good old 60Hz. punch region bass, the gut resonance is around one octave lower at 30Hz.
You can get 30Hz. output from drivers like the Selinium 15 swip, and this is done with the filter assisted Qb5 class I alignments.
The 60Hz. alignments are the class II of these and allow the full voice coil disipation to be used without exceeding the linear excursion limit, producing an average sound level of 125-130db.
The details of these alignments can be found on Rod Elliots site at.
www.sound.com.au

 

[Cal Weldon]

That would be under-utilization of both pieces of equipment.

With that kind of dB, I think it will suffice.

I don't think of PA bass as being wonderful yet at the same time <snip> my wife's comment was that the bass hit you in the chest. Sort of knocked the wind out of her for a moment. Is that what this driver does?[/B]

Hopefully.

Will it work with that plate amp in the way I described above? [/B]

I would think so. 250 watts into that driver is more than you'll need. Unless of course you like going to the dentist.

Is it the one you have, and do you swear by it [/B]

No, but I do own other similar Selenium stuff, and I like their bang for the buck.

I'm not suggesting this is the right approach for all but for those without the "golden ear" it can be as enjoyable as your wife's experience.

Cal

 

[Jan Dupont]

Who says that you need to use all 500W
Just be glad that you got your self high power amp.....
Choose the driver you first had in mind, and you got need system
which do not run out of power

Edit: Or use the extra power to electronic eq the woofer down in Hz ;-)

 

[simon5]

If 180$ is too much, you could go with this :

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-190

You seem to be sold on the NHT. Why not use two NHT?

Anyway, if you can spend 180$, the AV15 is definitely the way to go hehe! Just compare the specs, we are talking about 23mm Xmax versus 13mm for the NHT.

That woofer will achieve sufficient 30 Hz or 60 Hz punch anyway IMHO.

 

[cytokine]

You guys are great! Thanks for all the suggestions.

The topic that is getting lost a bit here is SQ. I haven't heard any of these products and so I'm making a blind purchase no matter what I buy almost.

I think almost any driver I match with this amp will produce more than enough SPL for my listening tastes. I mostly listen to acoustic jazz at moderate to low volumes and only occasionally do I feel a need to rattle the windows. I can do that any time I wish with the HT rig anyway. So really what I'm looking for is a good match for the PE 500W plate that will do that job.

I'm not necessarily sold on the NHT. In fact I'm really impressed by what I've read about the AV12 and the AV15. The $$ is not the issue for a change and I can buy what I need to make this sound really good.

I could get a pair of NHTs (if those sound best according to concensus of the forum) as ACD suggests and I have considered that. Hell, I've considered doing a wall of 4 . That would get the coveted eye-roll from Mrs. cytokine.

I'm not yet to the point of paralysis by analysis, but I'm getting close so I'm probably going to make a purchase soon just to get it over with.

What I guess I want to know now is, what parameters determine how good a sub will sound and can you tell the difference between similar drivers at similar price points?

simon, you keep coming back to the massive x-max of the AV as the comparable spec, and you also say it sounds good. Maybe that's the driver for me. I'm currently leaning that way as a way to keep the project "smallish".

Will the AV15 sound good in a sealed box (how big a box?) and can I make it down-firing?

 

[cytokine]

I just modeled a box for the AE AV15 using WinISD and it gave me a box about 1' x 2' x 3'. If I build this slightly smaller, will I be sacrificing some depth of bass in favor of a better transient response? That is to say, tighter more musical bass?

 

[simon5]

T/S parameters which can help you decide...

Low Vas (smaller box)
High Xmax (can achieve deeper and louder bass)
Low Le (less rolloff for the higher frequencies, better transient response)
Low Fs (can achieve deeper bass)
Low Qts (can achieve deeper bass)

This will give you an idea, but modeling each driver in WinISD using the same box size will give you even a better idea.

Will the AV15 sound good in a sealed box (how big a box?) and can I make it down-firing?

Sure it will sound good. How big of a box? You can use the size you want to use, bigger = deeper. Yes you can make it downfiring but John don't recommend it (It's his opinion on the subject that downfiring should never be used with any driver of any brand). If you look at other manufacturers drivers with the same set of parameters, you'll see that you can make it downfiring. Just don't be mad when in 10 years your subwoofer need a recone.

If I build this slightly smaller, will I be sacrificing some depth of bass in favor of a better transient response? That is to say, tighter more musical bass?

You'll be sacrificing depth of bass for a louder transient response. That driver is really good, you'll have "tight" and musical bass with any box size.

That driver will also make nice ported enclosures also if you're interested.

 

[rcw]

tight bass

Testing shows that below 50Hz. people can't hear the diffrence between suposedly "tight" bass and the more flabby sort.
Floyd Toole, who was a respected academic researcher before falling from grace and joining Harman international, has shown how "slow" bass can be majically transformed into "tight" bass by equalising the room resonance causing the slowness.
Incidentaly the punch peak that is characteristic of most live and recorded r&b, has more often than not a 6db. peak in it, and this confers a sealed box with a transient performance that is the same or worse than a reflex box.

 

[BAM]

As for sound, I think that the AE Speakers AV series drivers are some of the cleanest sounding bass drivers in their class, with very low distortion and very high output. I have my AV12 in a 3 cubic foot box with the dual 15" passive radiators, powered by the same amp you are getting. It can really move some air if you want it to. And then there are the looks of that aluminum cone. Come on, this is a no-brainer: get the AV-series drivers.

 

[cytokine]

Well, I was really sold on that driver despite the lousy website.

Still I'm conservative by nature and so I sent an e-mail a week ago asking if he had the AV15 in stock and how best to order because I wasn't sure of the website. I still haven't heard back from him.

That's a deal-breaker as far as I'm concerned.

My Titanic MKIII 15" showed up today and it'll be fine.

The wife is already rolling her eyes at me so I'm happy.

MDF is cut for the box and I'm ready to screw and glue tomorrow.

 

[BAM]

The web site isn't lousy. It's just not finished yet. Yes, the AV15 woofers are in stock. The ones at the reduced price have the wrong color zinc coating on the top plate. This doesn't affect performance, it just has a little less-than-consistent look to it.

 

[Chris8sirhC]

same boat

I'm actually in the same situation as you as far as what your building. I'm sorta waiting on the new generation of drivers to come out, or I'm going to try to get a lambda sub if I can figure out how...
but ill probibly end up getting the av15 too
http://www.diyaudio.com/forums/showthread.php?s=&threadid=63295

 

[cytokine]

May the force be with you.

I decided to go with the known quantity after much deliberation and box modeling. Since this is for home theater I'm somewhat less concerned about the SQ than I would have otherwise been. 'Deep and loud' is the main priority at this point and the Titanic didn't model that differently than the AV for that.

If you read my post above you know why I went with the PE product. Basically it's a company that I know will be there if something should happen and I need repair or replacement.

By the way, it's been two weeks and I still haven't heard back from the owner of the website where the AV is sold.

I'm finishing the box this week. I put the first coat of primer on the front and the back and am considering 1/4" poplar planking for the top and sides. That should give it a nice look, high WAF and solid vibration damping as well.

I'm probably going to bring it indoors tomorrow and test fire it to see if I like the way the box perfroms before going to the trouble of finishing it.

I too am looking forward to seeing what the new PE subwoofers look like as well. I wasn't prepared to wait for them for this project though.