4645B Subwoofers question

[avantrax]

Hi guys,
I run a couple of 4645B subs
Sound is great, punch is amazing but i expected some thing better on the very low frequencies.

After a tone test it is no present anything under 33hz
I was expecting to reach 25Hz

First doubt are the actual amplifiers that are some pro module from Mackie subs and could be they have some EQ / hicut built in. I'm moving to something like QSC, Crown, Carver.

Second doubt is the room to little (8,5mt x 4mt)
that doesnt allow frequncies blow a certain Hz.

Any help pease?

I'm considering also to use the two 2242 for building a TCB clone unit, maybe better for extreme low freq.

[Mike Caldwell]

You answered a question in this post that I asked in your other post about the amp.
Using an amp module out of a sub would include processing for the sub it came from.

Your subs need to high passed at around 20 to 25hz.

Class D amps are not so bad for subwoofers.

What is your budget for a sub amp?

[Riley Casey]

It's easy enough to test the amplifier with test tones to confirm that there is or isn't a high pass filter acting higher than desired for your application. Put a meter on the output and sweep a tone down from 80 hz and note the levels as you approach 20 hz. Mackie amplifiers are generally sold for live audio use and it wouldn't be surprising to find a HPF that cut off frequencies that would be a problem for live use.

[Mike Caldwell]

Like Riley mentioned about the high pass on the Mackie sub plate amp i'm going to guess is going to be
around 40hz.

I'm guessing you have some older Mackie plate amps, I looked up the older SRS1500 Mackie sub and it was rated at 45hz at -3db and at 40hz -10db. I'm going to say most of the Mackie subs are similar.

That said there was a time period when Mackie speakers were using RCF components made right there in Italy and that era Mackie speakers were not so bad.

Actually Italy produces some great speakers and components, B&C, RCF, Faital, 18 Sound and don't forget Powersoft power amps.

[g_t_r]

What today's power amp would be the best choice to drive 4645B/C subwoofers? (with +6dB EQ). Can you please recommend some example crown/qsc models? I would prefer to buy something "new" / or used, but still relatively "new".

[christo]

What today's power amp would be the best choice to drive 4645B/C subwoofers? (with +6dB EQ). Can you please recommend some example crown/qsc models? I would prefer to buy something "new" / or used, but still relatively "new". I use a pair of Crown's XTi 4002 Series 2 bridged - 2,400W in to 8 Ohms for my SUB18s. More than enough headroom and inexpensive all things considered. I crossover to the SUB18s at 58 Hz.

[Mr. Widget]

I would second the XTi recommendation.

We use Crown CDi amps for outdoor audio projects and they are solid performers and are reasonably flexible with their built in DSP. FYI: The CDi and XTi are essentially the same, but the inputs and outputs are physically different and the CDi amps offer 70V outputs which we use in large distributed systems.


Widget

[Robh3606]

I will triple that I use a Crown XTI 2002 for my subs. Just watch which model WRT fan noise. On my model you can run fans off until it's required or fans on all the time depending on use. I rarely have the fans turn on but when they do and things get quiet during a movie you can hear it. So just something to keep in mind if the amps are in the listening room

Rob :)

[sebackman]

Hi,

Unless you need to play stupid loud you can extend the ports about 1-2 inches and add some EQ to compensate. Those big 18's will be than enough in a residential setting without reaching x-max. I have done that on my 2216Nd-1 in the 4367 to dig deeper than in the originals. I have also done that on 4645C (singe port) with good results.

On the amp side my experience is that you should get an amp that can do 1ohm in stable operation or at least 2 ohms @>400w. You don't need voltage you need current to control the heavy cone. I would advise against bridge mode because that gives you more power (voltage swing) but not more current and that is what digs deep. I never use bridge mode for HiFi albeit for PA where power is most important e it has its place. Digital amps are just fine for sub use. I use a Crown CTS3000 for my SUB1500's sub in the other system. And newer digital amps (Ncore & Purify aso) gives any amp at any cost range a run for their money.

Enjoy the weekend
//Rob

[Ian Mackenzie]

In addition to Rob S post have a go at setting up REW on your Laptop and check out your rooms LF response. The latest version now offers comprehensive room modelling which l have found accurate to determine room modes.

[DerekTheGreat]

Hi,

Unless you need to play stupid loud... ...I never use bridge mode for HiFi albeit for PA where power is most important...

I play stupid loud. :bouncy:

I'm also settling in to using four amps bridged mono; two Crown PS-200's and two Crown PS-400's. I haven't noticed any caveats running this way, but have noticed better dynamics & detail. Bass is a smidge faster & punchier and I've noticed better separation/distinction between left & right.

[Rudy Kleimann]

Hi guys, I run a couple of 4645B subs Sound is great, punch is amazing but i expected some thing better on the very low frequencies. After a tone test it is no present anything under 33hz I was expecting to reach 25Hz You need to provide a 2nd order peaking high-pass filter with a Q=2 tuned to 25Hz to get the 4645B to do its magic. The 4645B, with its' two 5.25" diameter x ~24" long port tubes, is tuned to ~23.3Hz, perfect for the 25Hz peaking filter. I have one in my living room, driven through a slightly modified JBL 5235 active crossover. It has a built-in switchable 2nd-order peaking high-pass filter with settings to peak at 20, 30, OR 40Hz, and switchable mono summed LF output. I changed the filter caps to peak at 25Hz, per forum member 4313B's instructions. WINISD modeling indicates it to produce 24-55Hz +/- 0.6dB I'm very pleased with the results. The 20Hz stock filter setting in the 5234A and 5235 is ideal for the 2245H in a 12 cubic foot box tuned to ~18Hz.