Audible Nectar Posted March 20, 2002 Share Posted March 20, 2002 I'm looking for a good quality (used preferably, most bang for the buck) 2 channel amp for use with the JBL 4638 bass cabinets. It must be stable at 4 ohms. I've seen the use of the parts express plate amps by many on the forum, but I'm considering the separate 2 channel amp route. The plate amps are somewhat ugly (requires building a cabinet for them, and I would need 2) and I'm thinking that better quality amps would be found elsewhere. So, I have some questions while I wait for JBL to ship my units. 1. Am I correct in thinking that the separate 2 channel amp is the better way to go (performance wise)? 2.How much does the difference in these amps matter for good bass performance? 3. I the answer to #1 is yes, what amps should I be looking at? The JBL's are 100 db efficient, so they should get loud with many amps, but I want "clean, tight" bass. 200x2 @8 ohm - 300-400x2 @4 ohm is more than enough watts, but I want quality. Should I go home amp? Pro amp? Any recommendations?? 4. I am also considering the possible addition of a bass EQ (parametric) - I've read some about the Behringer feedback destroyer as an interesting option to flatten the response to the room. I would hook it up to the sub out on the HT preamp. Any knowledge on this subject here in the forum? My HT looks to be coming together now...I've got a set of Chorus on the way for the surrounds, and big woofage from JBL on the way via truck. Now if Outlaw can get me a 950 within the next month or two, then I'll make my Home Theatre page......... As always, TIA, Dave ------------------ First we Rock, then we Roll! This message has been edited by dndphishin on 03-20-2002 at 11:45 PM Quote Link to comment Share on other sites More sharing options...
T2K Posted March 21, 2002 Share Posted March 21, 2002 I don't know what you or anyone else wants or needs but if I had two of the JBL's to drive I'd do it with a Crown CE1000 or Samsom S1000 amp.You do the homework. Keith www.zzounds.com This message has been edited by talktoKeith on 03-21-2002 at 03:07 AM Quote Link to comment Share on other sites More sharing options...
Audible Nectar Posted March 21, 2002 Author Share Posted March 21, 2002 Thanks, Keith. I have little knowledge of pro amps (other than the fact that many use them to power their SVS). The Crowns and Sampsons do seem readily available. ------------------ First we Rock, then we Roll! Quote Link to comment Share on other sites More sharing options...
jnorv Posted March 21, 2002 Share Posted March 21, 2002 I am using a Bryston 4b for mine. They have a high damping factor and put out about 400 w at 4 ohms. They can be had for $450 and up from Audiogon. I am using a passive crossover that I built with the advice of mdeneen. See the passive crossover thread on the 2 channel page. My 4638's came wire in parrallel which puts the effective impedence at 2 ohms (dc). I rewired mine to run in series (8 ohms). Jim Norvell Quote Link to comment Share on other sites More sharing options...
J M O N Posted March 21, 2002 Share Posted March 21, 2002 Jim: I believe the 4638 system itself is 4 Ohms (as it is already wired). If you rewired it, you are probably at 16 Ohms. Quote Link to comment Share on other sites More sharing options...
Audible Nectar Posted March 21, 2002 Author Share Posted March 21, 2002 JMON is correct - the system is a 4 ohm system, as is. ------------------ First we Rock, then we Roll! Quote Link to comment Share on other sites More sharing options...
jnorv Posted March 21, 2002 Share Posted March 21, 2002 You could well be right. I was basing my conclusion on the DC resistance of the voice coil. Jim N Quote Link to comment Share on other sites More sharing options...
TBrennan Posted March 21, 2002 Share Posted March 21, 2002 jnorv---A driver's impedence varies with frequency and the DC resistance of the coil at rest actually doesn't tell you much about how the speaker works. Check the impedence curves that are on the 4638 spec sheet. If JBL is rating the cabinet at 4 ohms there's a reason. This message has been edited by TBrennan on 03-21-2002 at 11:56 PM Quote Link to comment Share on other sites More sharing options...
Chipp4 Posted March 22, 2002 Share Posted March 22, 2002 dndphishin, We are thinking the same on this project. I believe I am going to go the pro route (at first I will have to use my Adcom 555II at 325w/ch). I have researched the Crown CE2000 & XLS 602, Crest Audio ST2000, QSC PLX 2402 & RMX 2450 and the Yamaha CP2000. My biggest concern would be the fan noise so I was thinking about renting one of these amps from a sound company and trying it in my room. I personally would stay away from Samson. Just look at how much power they say they put out and the price is so cheap compared to the others mentioned above (and the ones above are their companies less expensive stuff). You can't ever have to much power. As far as eq is concerned I'm not sure if thats really necessary or not. Quote Link to comment Share on other sites More sharing options...
Audible Nectar Posted March 23, 2002 Author Share Posted March 23, 2002 From reviews I've read, the Crown CE series amps fans rarely run (only when worked extremely hard). They should be more than adequate for sub use - I've found several users of pro subs in Google searches using the Crown CE series with good results. I've located a like new CE 1000 and BFD at a very good price - it looks like I've got power for the JBL's now. The CE 1000 should be plenty of power, given that this gear is going in my living room. If it's not good enough, I'll have no trouble recouping the investment. In 7-10 days I should have the gear here - I'll give a report. ------------------ First we Rock, then we Roll! Quote Link to comment Share on other sites More sharing options...
force95 Posted March 23, 2002 Share Posted March 23, 2002 I know the literature for the JBL 4638 says the impedance is 4 ohms. On the 4638 I got last week the sticker on the back says it is 8 ohms. Is this just the wrong sticker, or is it saying that each speaker is 8 ohms and since it is wired in parallel the impedance is 4 ohms? What does everyone elses sticker say? Benny Quote Link to comment Share on other sites More sharing options...
kenratboy Posted March 23, 2002 Share Posted March 23, 2002 Yo ,Yo! STEP 1: TURN OFF THE AMP BEFORE ATTEMPTING!!! ---------------------------------------------- Now, take a volt-ohm/multi-meter (if you have one) and put each lead onto one of the speaker terminals. Now, here's the guess work. My JBL 4648A-8 IS 8 ohms. Upon putting the leads to the termainals, I got a reading of 5 ohms. If you do this same test and get 3-4 ohms, it is probably a 4 ohm load. Just try it if you want. Also, pull the woofers and read the back. If eash woofer is 8 ohms, it is a 4 ohm load for the whole sub. If each woofer is 16 ohms, like mine, you will have a 8 ohm load. NOTE: JBL uses BLACK as POSITIVE on my speakers. The hook up terminal "should" be the same. If you open your speakers (just do it=fun ) make sure you note which cable plugs in where. Enjoy! ------------------ Receiver: Sony STR-DE675 CD player: Sony CDP-CX300 Turntable: Technics SL-J3 with Audio-Technica TR485U Speakers: JBL HLS-610 Subwoofer: JBL 4648A-8 Sub amp: Parts Express 180 watt Center/surrounds: Teac 3-way bookshelfs Yes, it sucks, but better to come. KLIPSCH soon! My computer is better than my stereo! Quote Link to comment Share on other sites More sharing options...
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