DIY subwoofer advice

[TheEAR]

I am sold to Crown, XTi1000/2000/4000. I will end up with two XTi2000(each bridged MONO) to drive my dual TC3000 15" sealed monolith.

Next on the meny more Crown another set of XTi and ...iTech...probably two of these powerhouses.

I understand the classic class A/B with the big/heavy transformers may be preferred to the switching type. I like my heavy ATI,Bryston,SimAudio,Krell brutes...and how about the 15W Tenor monoblocks...AH only 15W but the best 15 watts x2 lowly ears will even hear(providing proper speakers ...8-16 Ohm stable). 75lbs per amp...15W.

For sub duty a good Crown or QSC does great, here high damping and being capable to deliver major juice into difficult loads reigns supreme.

[Guest srobak]

you can find a few PR's(Paradigm among others) that use NO spiders ! Just a well designed stiff sourround with proper recall.

Paradigm did this, eh? I did not know that - learn something new every day. Good info - Thanks Chief SubALot

[TheEAR]

Paradigm uses this type of spiderless,basketless(the basket is the front ring frame) PR's in the Seismic series and UltraCube.I think another company uses this ...have to dig.

[TheEAR]

Woofaz to move air. And have ventilation in da summer. [] Woof the woofa

[TheSoundBroker]

I am sold to Crown, XTi1000/2000/4000. I will end up with two XTi2000(each bridged MONO) to drive my dual TC3000 15" sealed monolith.

Next on the meny more Crown another set of XTi and ...iTech...probably two of these powerhouses.

I understand the classic class A/B with the big/heavy transformers may be preferred to the switching type. I like my heavy ATI,Bryston,SimAudio,Krell brutes...and how about the 15W Tenor monoblocks...AH only 15W but the best 15 watts x2 lowly ears will even hear(providing proper speakers ...8-16 Ohm stable). 75lbs per amp...15W.

For sub duty a good Crown or QSC does great, here high damping and being capable to deliver major juice into difficult loads reigns supreme.

The Crown amps are good ones...I wouldn't sell them if they weren't. But if you are looking for the best bass there is, a big old honking traditional Class AB amps with boatloads of capicitance and a monsterous power supply is still the way to go. The design is optimized for low frequencies where the Crown and QSC's touring amps are optimized for running higher frequencies at stupidly insane power levels for several hours. Sustained LFE isn't necessarily what they had in mind when they designed them. They do deliver massive amounts of power, but side by side, there is definitely a difference in the quality of the lower registers (I've done the comparisons). There is always the Bryston 28BSST 1000 watt monoblocks if cost isn't an object. Great god almighty are they magnificent! Point is, if you are gonna build the ultimate subs, try one of the Face amps (the Guys at DIY Cable discovered them too) and I know you'll be converted.

[TheEAR]

SoundBroker,

I can use my Krell(1200W into 4Ohm load per channel) or bridge my Celeste 4250SE (1KW into 8Ohm load) ...what a waste. Crown iTech4000-8000 it is.

Thanks for the options,I may very well end up buying some of those. Who knows,with my compulsive purchases,and changes...heh.

[michael hurd]

"(Ahem...cough) Face Audio F-2000TX. Sell them both, did the direct
comparisons. Equivalent rated power to the IT-4000, but an old school
Class AB design with a massive power supply. Needs a 30 amp line for
the best performance (then again, so do the ITechs), definitely more
potent down below as it is optimized for LFE use. Also, Crown is
reissuing the MacroTech anniversary editions which look SWEET but will
probably be snatched up quickly. Lot of guys in the touring industry
(except the roadies) miss their Macrotechs which are...ahem...old
school class A/B designs with massive power supplies. Concensus is they
sound better. Also need to play around with the newest potential cheap
uber amp king, the new XLS 5000 which is (TADA!) 2 ohm stable! That
means they may have actually put a halfway decent power supply in there
(kinda have to with 1100/ch into 8). Lot of horsepower for $1395."

Any proof of performance>? On the AVS forum where there is actual independant testing, there are quite a few SMPS amps that kick the old iron so far into the dust it is not funny, both in high frequency measured voltage and low frequency ( 20 hz ) testing.

[DrWho]

I was gonna say....if there is anything that a switching amp does well, it's gonna be the low frequencies!

[TheEAR]

Exactly,switching amps may not have glorious weight but for subs they are ideal choices. I will look up the Face Audio F-2000TX ...just to see what the noise is all about.

[TheSoundBroker]

My comparison was between the IT-4000 and the F-2000TX. Level matched and I used about 4 different passive subs including a quad KW-120 array and a Danley DTS-20. The biggest difference was the sheer sense of weight the Face had at the very lowest frequencies. There was definitely more room shuddering happening with the F-2000's in line. Keep in mind, I was happy with the Crown amps and didn't have any real intention of adding another power amp line, particularly one that isn't as well known...but the listening tests and trials couldn't be ignored.

One thing to keep in mind, and this is an advantage the switching amps have...I also have proper power supply for my amps...twin dedicated 30 amp lines for my LFE system. For somebody who has a 20 amp line and an impedance heavy LFE system with extreme extension, the switching amp makes sense as it will draw the line down less than the AB amp and it will be less current limited (though a larger line is still required for some of the uber amps like the 8000). A touring power (1KW/ch plus) class D switching amp on a 20 amp line will outperform a traditional heavy iron A/B amp on the same line since the heavy iron amp is current starved due to the lower efficiency. However...feed the AB amp adequate juice and the tables turn as the more massive power supply reserves come into play. Again...I'm not trying to slam the Crown and I recommend them all the time to folks and they ARE incredibly awesome power amps, some of the best on the planet, but I get more sheer impact from the old school design.

[michael hurd]

I would really like to see a side by side comparo of multiple amps, with some objective measurements. There are many things that can skew a test as: phase change inside the amplifier ( possibility of cancellation with mains ), differing input sensitivities * ( Crown IT 4000 is adjustable from 1.4 V in to 7.75 V in , F-2000TX is 0.775 to 1.0 to 1.4 volts selectable. )

There are good and bad examples of both linear and switching power supply amps out there.

[DrWho]

One thing to keep in mind, and this is
an advantage the switching amps have...I also have proper power supply
for my amps...twin dedicated 30 amp lines for my LFE system. For
somebody who has a 20 amp line and an impedance heavy LFE system with
extreme extension, the switching amp makes sense as it will draw the
line down less than the AB amp and it will be less current limited
(though a larger line is still required for some of the uber amps like
the 8000). A touring power (1KW/ch plus) class D switching amp on a 20
amp line will outperform a traditional heavy iron A/B amp on the same
line since the heavy iron amp is current starved due to the lower
efficiency. However...feed the AB amp adequate juice and the tables
turn as the more massive power supply reserves come into play.

The
higher efficiency of the switching amps just means the FETs run cooler,
or in other words, a smaller heatsink can be used. When running at peak
output, the efficiency of a class AB is going to be rather close to
that of a switching amp. I'm not making the point very well, but the
point is that the difference in power sag really has very little to do
with the topology....it has more to do with the amount of capacitance
on the power supply rails. In other words, there is nothing preventing
a class AB from displaying similar power draw characteristics from the
wall to that of a switching amp.

I guess I'm being nit picky
since switching amps will generally require more capactiance since all
of the energy is being stored there, but really your class AB designer
could be doing the same thing...

In all honesty, I think the only
way you're going to notice much difference between power amps driving
subs is when you're getting into the clipping region of the
amps...class AB sound fuller than class D when they're distorting.
Also, class AB is gonna have a lower damping factor at the lower
frequencies which makes the bass seem fatter - although it
might be argued that this kind of fatter is less accurate. Depending on
the application, fatter is probably a good thing so I can totally
understand the preference.

Well that's my 2 cents anyway - I hesitate making such general
claims like this because everything is an exception to the rule...I can
see how I'm approaching this from a perspective of someone building
amps rather than someone looking for the best amp to put into their
theatre...I guess I can only say that I wish that I've had more
experience with these amps in the home rather than just prosound (and heck, there's a lot of new stuff coming out too that I haven't heard yet either).

[TheEAR]

The well designed switching amp is not impressive like the classic class A/B amp. It is light weight,people will pick it up...oh light ...cheap power supply. Wrong , you have very capable switching amps,where the voltage regulation and reserve caps can provide all the cont. and burst one may ask for.

I agree with DrWho.

Amps like the Crown iTech are PERFECT for subs,the iTech makes a big Krell,Mark Levinson or Jeff Rowland look bad,as it has enormous damping and that is for starters.For something that weighs around 30lbs it packs a punch of a 250lbs class A/B brute. No monster heatsinks(fans help too),efficient design and the huge mains transformer is gone.Switching amps can be quite complex and sometimes fail more often than simpler class A/B designs.

[Jay481985]

I simply like the crown xti because the fan does not turn on till it needs too, looks straight at qsc with the always on fan.

[TheEAR]

Grainy pic,sorry. Just one brace.

[TheEAR]

Goodies from tonight's visit at HD. Save for my "old" PT jig (does not even fit this router). Freud all the way and BTW...this router will only be used for roundovers and port flaring..I have larger bit capable of making 1" roundovers(largest that will fir with the attached base)!

Freud bits are not cheap but quality puts to shame the cheapo garbage made in...ahem. All these bits are made in Italy,the drill stuff in Austria.

[TheEAR]

New driver arrived today ! Pics to come... HE HE. DIY frenzy in full effect...

[TheEAR]

Take a good look at this thing,looks like not much...it is a heavyweight among drivers under $300. Pics cannot do this unit any justice.

[michael hurd]

Nice looking unit Arthur, is the surround foam or a rubber? ( can't tell from the pictures ) BTW, I also have a few pics from today for show and tell.

Can you tell what this is for>? This was to verify the correct angles, looks like a winner. []

[michael hurd]

A stack of 8 sheets of MDF in 3/4 inch.... who could those be for???? []