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Any opinions on the JBL 4638's...


CharlieTuna

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quote:

They have the 4638 on sale right now for $216, check it out here (
). What about this sub? You can not beat the price. They have a little over 300 of them.


Any more opinions on this sub. Seems like a steal for $216.60, shipped.

Thanks,

CT

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You can tune a radio, but you can't tuna fish!

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charlie,

I too have been looking at these tent sale prices and they are very tempting. There is a couple of people that are one this board that have bought these speakers.

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Home Theater:

Yamaha RX-V1000

Klipsch RF-3's

Klipsch KSC-C1(LOOKING FOR A RC-3 OR RC-3II)

Kenwood KSV64 Bipolar Speakers

Klipsch Subwoofer KSW-12

Television: TOSHIBA THEATER VIEW 50"

DVD Player SONY S-360

CD Changer CDC 585 5 Disc Yamaha

Harman Kardon TC-1000

monster cable interconnects/12 gauge speaker wire

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Ok, here's my two cents...

Caveat:

By trade, I am a software developer. A pretty damn good one (sorry, just my opinion). So, despite I know a little about physics, I am not an electrical (or acoustical) engineer and therefore cannot absorb and discriminate the specifications of speakers and such. I am an audiophile neophite like many on this forum and am hear to learn from others. However, I have enever been accused of being short on opinions.

So:

The ohm rating is a measure of resisitance or opposition to the flow of electricity through a circuit (the speaker in this case). What's important is that you match the capabilities of your amplifier to the specifications of your speaker. Therefore, you should drive this JBL with an amplifier spec'ed for 4 ohms as well as matching the power ratings (you don't want to overdrive the speaker or underpower it). This may require a separate amp. I cannot address the other parameters such as POWER HANDLING CAPACITY, OUTPUT CAPACITY and FREQUENCY RESPONSE other than saying that it looks like it can reproduce frequencies down to 30 Hz. Now, as to HOW WELL it does this, I cannot say (I'm sure this is where total harmonic distortion comes to play).

Anyway:

I have decided to order one. For $216.60 total, I've got to think that at least as "general reinforcement" as JBL puts it, this sub will improve your system. If not, oh well, you takes your chances and learns something (hopefully). I still plan to get another sub that goes below 30Hz, probably SVS 1646CS+(?).

CT

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You can tune a radio, but you can't tuna fish!

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I have a JBL 4648A-8. It is the 8 ohm, dual 15" sub, but it has better woofers. It cost $220.21. Anyway, like I said in a previous post, it will smoke ANYTHING over a thousand or more dollars, the catch? It's 4' X 2' X 18" and weights as much as a normal person (or so we would like to think)

Preformance, bass down to 25Hz that will liquify your bowels and ruin your house. It is not SLOPPY sounding, it produces sounds like a kick drum with a punishingly pleasurable smack. It will, most importantly, give you bass at ANY level that you could stand, and I'm a bass head!

Amps? I have a $130 Parts Express SUBWOOFER amp. At 8 ohms (my load) it puts out 180 watts, this will give me a headace and make my knees turn to jelly, sereously! At the 4638's load, it will put out 250 watts. It has a good warranty, so if it got fried with the 4 ohm load, send it back! The partsexpress.com number is #300-794, and its ONLY $130, got it.

Figure, it doesn't get any cheaper than this, so order one and report back to me, I am sure you will enjoy it! If you don't, either your a snob, or a *******. Remember, these are the EXACT same woofers and enclosures used in the best movie theaters, concerts, and other commercial sound applications, they are TOOLS for people to make money with, they sound good and JBL has a no frills, no nonsence approach to business, they take good care of you. This sub is engineered to take decades of abuse from the idiots that run movie theaters, so you will have a hell of a time breaking them!

GO NOW, order, what are you waiting for? I think this is the ultimate toy for a audio freak!

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Hmmm, 1600 watts peak? I think that should hold you over for a while, unless you listen to music/movies in a gym! One thing I can say, is that, they are so sensitive, you really only need that parts express amp or somthing small. It's funny, I tried to run the sub with an Aiwa bookshelf receiver (sort of crap) and an old Mitsubishi receiver (total crap) and they both refused to move the woofers at all. I get the 180 watt parts express amp and it is like opening a 12" water main as opposed to a bathroom tap!

My sub's woofers cost $350 each, so $700 for the woofers, another $300 for the cabinet, and, eventhough shipping is FREE, it could have cost me another $100. That means this sub could have cost me $1100!!! The 4638 would probably be about $200 cheaper, but still, thats like a Good Will or Salvation Army find with a 5-year warranty!

My sub's woofers (2226J) have a 4" voice coil, and can move 1.6" total, the 4638's woofers have a 3" voice coil, and I think about 1" excursion. I always feel like my woofers, no matter how durable, will blow apart when they get moving. The JBL's can take SOME abuse. Anyway, order and enjoy!

NOTE: after you order, you will get NO e-mail conformation. Give it 24-48 hours and call JBL, the nice people there can tell you if you got taken care of or not. They don't play games with you, they just play nice, because of a woofer problem (isolated, don't worry!) I probabely called them a dozen times and was able to get who I wanted quickly. They want to keep Professional after there name.

TO KLIPSCH: yeah, this is like having a union meeting in the lunch room on company time or having a town meeting to plan the removal of the city council, but what can I say.

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Just so you understand that this JBL is a woofer not a subwoofer. However they go pretty deep; placed along a wall (a 2-boundary situation) and with the 6db at 30hz bassboost of my Parts Express plate amp my pair of 4648s is flat down to 25hz, the lowest reading available on my RTA. That's very good and they'll do this 25hz at 124 db all day long. I'd expect very similar performance from the 4638. As Ken says these are very low distortion devices, in fact the lack of distortion makes them sound less "impressive" than home subs that make huge amounts of 2nd harmonic distortion or "doubling". They don't rumble like most home subs; they hit hard, shake the house and then quiet down until the next hit. Very clean and very "transient".

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I have looked at the PartsExpress amp (part #300-794).

A few questions for TBrennan:

How/where did you mount this amp?

Did you make any EQ modifications?

CT

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You can tune a radio, but you can't tuna fish!

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TomB.: Good point. Although I don't understand the different types of distortion, I now notice that the sub dosen't "rumble." I guess this makes it a better MUSIC subwoofer than a MOVIE subwoofer. I know exactly what your talking about, kick drums are SOOOOO fast, they are bucking to hit FASTER than my 6.5" bookshelf woofers! I thought 15" and 18" woofers were supposed to be slow and sloppy, the JBL's are faster than my 6.5" bookshelf speakers. Like I said, a true MUSIC sub, I think (see below).

Chicken of the Sea: I know you are asking this question to Tom, but let me take my side alsoSmile.gif. I have done no EQ mods, the 30dB. boost is the default, but I have read that the boost can be modified by removing the "non-lethal" circuit board.

As for mounting in, HA! Its sitting on a wash cloth on top of my desk with the connector and power plugged into it. I WOULD NEVER, EVER CUT MY SUB OPEN AND MOUNT IT IN THERE!!! What I may do is make a small box so I can put the amp on my all-matal equiptment rack. The transformer is on the bottom, so setting it somewhere is safe as it will not tip over, even if it did, it probabely wouldn't hurt it.

Mike: Right on with the SVS's! I was about a week away from ordering one of the cheaper SVS's and the Samson amp. If I need to, in the future, I may dump my JBL (if real life wins the audio game!) and get a pair of the expensive SVS's. I think the common theme with good subs if "bigger is better." The JBL OR SVS will not hide under the end table!

Any thoughts on a sub that doesn't distort and "rumble." Does this make the JBL a good music sub and a sub-good movie sub? Any thoughts or suggestions? Should a good sub distort at all (I mean a noticable amount)

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ratboy,

Thanks for chiming in; that's what a forum is for. I was curious as to how people were housing the amp. And yes, I have no intentions of modifying any sub/woofer box. I too have been looking at an SVS or something similar for a new sub. However, after just receiving a new KLF-C7 (wow) and in the process of obtaining some Chorus IIs, I am looking at some short-term/less expensive alternatives. The JBLs look like a decent solution. And, at some point when/if I get another sub, I may just keep the JBLs in line for that added power and feel.

Is it necessary for a sub to distort in order to be a good movie sub? I would think accuracy in music and movie soundtracks would be most desireable.

CT

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You can tune a radio, but you can't tuna fish!

=====================================

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Tuna: Are you Dolphin-Safe?

Like everything in life, there are tradeoffs, in the case of the JBL, its size, but two SVS's will take up MORE floor space than the JBL. Some, non-audio lovers will find an 8 cubic-foot box repulsive in a living area, so beware, this thing doesn't hide from sight in the slightest. Again, this is a deal that sounds too good to be true, but its the real thing, no catch.

With the distortion, I am going to borrow a pro audio (like concert) reverb and put a few mS of delay on the sub signal and see if it adds more impact, I will only do this for movies, as the music sounds too good to mess with.

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I dunno Charlie, but if you getting Chorus II's the JBL will probably match up real nice.

It does depend on the room however.

Ken,

If I had known about the JBL deal at the time, I would has saved the money and went that route.

I kind of think the high efficiency factor of the JBL

would be more of a better matchup for 101Db sensitivity

Chorus II's.

(Which I have, BTW.)

Don't get me wrong, the SVS's match up nicely.

The dig down, tuned at 16 hertz, and there is very little Boom.(Which is more from room acoustics, probably.)

If you can live with a eight foot cabinet, it's a good choice, especially for mostly music listening, even for HT, except a little less depth in bass.

I'm using a NAD 2100 power amp Bridged to mono, with the sub's series wired.

With a Audio Control Richter Scale II bass EQ crossover, Tweaked a little with bigger caps.

Sounds pretty damn good, a little more poking around of course, it never ends when your hooked, BEWARE!

I have the Jon Pomann active crossover 'Explorer Kit'.

It's a breadboard with parts, documents and Schematics.

I have built the three way version and tested fine, and now need to built the active subwoofer version, for the SVS's.

It's a fun way to learn about active filtering, a must for subwoofers and woofers.

I need to get a damn test tone CD, I wonder if I could find one at a Hock Shop?

THANX!

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Thanks for the feedback (kenratboy & mike stehr).

If all pans out, I will have:

Pioneer 45" rear projection TV

Yamaha DSP-A1 amp

Chorus II mains

KLF-C7 center

Quartet rears

Either Quintet or KG 1.2 front effects

JBL 4638 (sub)woofer

along with Monster interconnects, 12G wire and HTS 5000 power filter.

Not too shabby, I think. This should hold me for a while (my rels and friends think I'm nuts).

CT

------------------

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You can tune a radio, but you can't tuna fish!

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Charlie--Build a simple 3 sided box the height of the "plate" open on top and bottom, screw the plate amp to the sides and you'll have a nice little 4 sided box. A couple of guys I know are simply letting the amp sit flat in the egg-carton like shipping protection it's packed in, this works well and looks neat. I have not fiddled with the EQ.

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Ken---As for fast woofers, think of it like this. The JBL 2226, with it's 4" edgewound voicecoil, very large magnet and light paper cone, has a much better power-to-weight ratio than small hi-fi woofers. Plus the 2226 doesn't have to move near as far as a small woofer for a given frequency and volume plus you have two 2226s so even that small excursion is cut in half. So thinking that small woofers are faster is like thinking that a Hundai can do a standing start 1/2 mile quicker than a Street-Hemi can do a standing-start 1/8 mile. Actually I think the impression of speed is a function of distortion and driver-box damping. And 2-15s makes for very low distortion as distortion in woofers is directly effected by excursion; as excursion goes up distortion goes up.

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