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Amp for JBL 4645c sub

7K views 19 replies 8 participants last post by  Reddig 
#1 ·
I'm considering buying a used JBL Cinema 4645c I ran across. Good deal as long as shipping isn't too much but I'm sure it prolly will be pricey. Hope not.


Started thinking about what amp I would drive it with. I need one that has a sub sonic filter and I'm sure many of you are familiar with the JBL 2242h woofer. Any particular amps come to mind? Love to be able to use an EP4000 but don't think it has a low enough filter. Thanks guys.

Edit: http://www.jblpro.com/pub/cinema/4645c.pdf
 
#2 ·
what about the iNukes?
 
#5 ·
iNukes are loud but the DSP is pretty functional. I believe the JBL subs call for a 20 Hz HPF, but could be wrong. The DSP of iNuke should be great for this sub as adjustments onky go to 20 Hz (there are workarounds for lower frequencies).


Crown also has a lower cost DSP amp that is quieter than the iNukes.


Awesome sub if not looking for sub 20 Hz bass.
 
#6 ·

Quote:
Originally Posted by NWCgrad  /t/1510073/amp-for-jbl-4645c-sub#post_24167263


iNukes are loud but the DSP is pretty functional. I believe the JBL subs call for a 20 Hz HPF, but could be wrong. The DSP of iNuke should be great for this sub as adjustments onky go to 20 Hz (there are workarounds for lower frequencies).


Crown also has a lower cost DSP amp that is quieter than the iNukes.


Awesome sub if not looking for sub 20 Hz bass.
Cool. Ya 20hz I is where the high pass needs to be. Says 12db/oct or higher and I would think a steep filter would work best. Ya def not looking for ULFs with this. Attracted to it's 25hz and up performance. Too bad the inukes are loud dam. Can you do amp mods on them?
 
#7 ·
I don't know what you are looking to spend, but an XTI - 2002 crown or a used XTI 2000 ebay would work nicely. Bridge for 2000 watts. Download HiQnet and it should have a setting you can select for that sub.


Variable speed fan, but in practice, I never hear them. The driver in that sub has 54mm of xmech so the chances of hurting it are small.


HiQnet


 
#9 ·
Thanks Tack and NWC i appreciate it. I would love to get a used Crown XTI. That's what I'm gunna keep an eye out for. I'll research a lil too before taking the plunge. Crown has always been an attractive amp solution. Have heard so much great testimony both by fellas on AVS as well as some of my commercial cinema friends. I'd rather b patient and find a good deal on a used one cause this is kinda my budget used sub/amp add on to my HT. I'm eventually gunna piece together an entire JBL PRO Cinema system. I already use JBL 8340a surrounds i got used. Would love Crown power for future JBL screen arrays and my surrounds too. When that happens I'm moving my gear rack to an adjacent room so loud fans won't be an issue.
 
#10 ·
Tack was looking at the ebay link you posted and man that seems like a dam good deal for that as long as it doesn't bid too high. What do you think? Says it was rack mounted all it's life. Tempted to bid on it before the sub.


Edit: found some more info
http://billfitzmaurice.info/forum/viewtopic.php?t=5935

Man the dsp is so slick and seems like just the ticket for that sub.
 
#11 ·

Quote:
Originally Posted by Reddig  /t/1510073/amp-for-jbl-4645c-sub#post_24169489


Tack was looking at the ebay link you posted and man that seems like a dam good deal for that as long as it doesn't bid too high. What do you think? Says it was rack mounted all it's life. Tempted to bid on it before the sub.


Edit: found some more info
http://billfitzmaurice.info/forum/viewtopic.php?t=5935

Man the dsp is so slick and seems like just the ticket for that sub.

I've never had a problem with a Crown amp, but even if you did, they are fixable. There's one in my shop that's been "on" for 2 years.


The DSP should have pre-sets for your future Screen Arrays too. Stack 'em up
 
#12 ·

Quote:
Originally Posted by Tack  /t/1510073/amp-for-jbl-4645c-sub#post_24169651


I've never had a problem with a Crown amp, but even if you did, they are fixable. There's one in my shop that's been "on" for 2 years.


The DSP should have pre-sets for your future Screen Arrays too. Stack 'em up

OH YEAH!!!
 
#13 ·

Quote:
Originally Posted by Reddig  /t/1510073/amp-for-jbl-4645c-sub#post_24169489


Tack was looking at the ebay link you posted and man that seems like a dam good deal for that as long as it doesn't bid too high. What do you think? Says it was rack mounted all it's life. Tempted to bid on it before the sub.


Edit: found some more info
http://billfitzmaurice.info/forum/viewtopic.php?t=5935

Man the dsp is so slick and seems like just the ticket for that sub.

Two hours left.
 
#14 ·

So I'll start by saying I'm a bit of a craigslist poacher and am limited by what comes up at a wildly low price every now and again...

 

I'm currently driving mine with a QSC ISA 800Ti  (gain fully open, bridged mono is 1500W @ 8 Ohms) using a behringer FBQ1502 EQ in input mode to attenuate (it pretty much stays at -10dB all the time). It sounds good enough for my purposes, though I'm fairly new to this hobby and may be doing something incredibly stupid without knowing it. I know this amp isn't really designed for this application and am reassured by comments in the thread that this sub is tough. Am I doing something stupid, though?

 

From listening I also suspect that the Sony 1000ESD preamp's subwoofer channel removes the lowest frequencies -- not sure if it has a hi-pass built in in the neighborhood of 20 Hz.
 
#15 ·
Cool thsnks for posting.


Was looking at that amp and it says it has a sub harmonic filter so the amp could be cutting off at 20hz which is a good thing with this sub as it needs to be high passed.


Instead of getting a new sub I decided to get new LCRs. I got 3 2x15" cabs from the JBL 4722 and the 3 in equivalent CD from P-Audio on JBL 2380a horns. Each has a 1,200 hz 2-way passive crossover board attached to the tops of the cabinet. Also got 2 Crown DC-300a Series II amps to power them. Each is 300x2 at 4 ohm. Just installed and hooked them up a couple days ago and they are beastly! Just love the midbass and dynamics of these and the gigantic sound they have one second than soft and delicate the next. I'd love to bi amp them.


Edit: what crossover point are you using for your 4645c?
 
#18 ·
Im still interested in buying and running a pair of JBL 4645C and with my setup now I could put the amp out of the room so noise is not an issue anymore. Wondering what Crown to look into. Would a Crown XTi-4002 be enough power for a pair of 4645C's? I need to look into how low the shelf goes on the amp. Needing a 20 hz hpf on both subs.

https://www.crutchfield.com/p_859XTI4002/Crown-XTi-4002.html

I want more headroom then my dual Power Sound Audio XV-15se give me though they do sound nice. Just want more headroom. Dont need ultra low sub 20hz bass.
Will look into the specs later after im not so busy. Just want it to power dual 4645c's to reference and over cleanly . My entire system speaker wise is JBL Pro and always wanted two of these.
 
#19 ·
Yeah, that will do it for power. I highly doubt you will use even a fraction of that power most of the time in a house. Especially if you want to keep the bass somewhat balanced in relation to the lower bass from the PSA. It will crush them in the upper bass to lower bass ratio and the lower bass is much harder to make.

I added some PA/Pro style woofers to my system and I did like it but they need very little power to get loud in the midbass range.

What mains are you using?
 
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