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Thread: Amp for bass driver

  1. #1
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    Question Amp for bass driver

    Hi,

    I am planning to try bi-amping my 4344 Mk2's. JBL recommends an external crossover at 290Hz. Everything below that goes to an ME-150, which is a proprietary driver that replaced the 2235 in the original 4344.

    I will be using a 10W SET on upper three drivers. The output impedance of my particular amp is 1.5 Ohms.

    What should I look for in the amp for the bass? Should I try to find one with a comparable output impedance to the upper range amp? Should I get an inexpensive/used pro amp with plenty of power? Suggestions?

    Thanks!

    - Ken

  2. #2
    Moderator / Treasurer/Marketplace Czar boputnam's Avatar
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    Uh, oh...

    You should, if you haven't already, peruse this most interesting Thread: "Amplifiers are more significant than you think" Thread. Yuri and others will likely come through with some useful "first hand opinions" (hmmm... I LIKE that one ), too.
    bo

    "Indeed, not!!"

  3. #3
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    Re: Amp for bass driver

    Hi Ken,

    "What should I look for in the amp for the bass?"

    As with any large JBL LF transducer having a 4" voice coil - an amp that can dump a lot of current and can handle low impedance loads.

    "Should I try to find one with a comparable output impedance to the upper range amp?"

    Not unless you like that particular effect.

    "Should I get an inexpensive/used pro amp with plenty of power?"

    Plenty of power, plenty of current capacity.

  4. #4
    Super Moderator jblnut's Avatar
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    inexpensive pro amp - yes, yes, yes

    I would recommend you check out the older Yamahas (PC2002M, PC2602, etc) or Carver (PM 175,PM350, PM700). I've had exellent luck with both. I drive my L250's with a PC2002M and my home theater sub with a (bridged) PM175. Others here could recommend similar QCS or Crown units I'm sure....

    I'd say that in general, a good used pro amp will deliver everything you're looking for at 1/10 the price of an "audiophile" amplifier. They are built tough and they will likely last a lifetime if well cared for.


    jblnut

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    Re: Amp for bass driver

    In case anyone cares, here's the latest blurb from JBL:
    Attached Images Attached Images  

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    Your Memory Lives On RIP Tom Loizeaux's Avatar
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    Adcom and B&K make quality high current power amps that are quite affordable and a good value. These will drive your JBL woofers to optimum performance. ( You can always go bigger and better ie: Mark Levinson, etc.) I feel 100 watts per channel is the MINIMUM you should go with. Remember, JBL said that your power amp should be able to deliver double the wattage capacity of your speaker if you want high level, monitor type playback.

    Tom

  7. #7
    Senior Member MikeM's Avatar
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    Amp recommend

    On the jbls woofers maybe try a good fast maybe a bit dry sounding Lf amp. Adcom 555II will suprise you. Thats agreat Bi amp amp. the highs and mids are very forward.The 5802 and 5500 sound VERY diffrent and dont havr quite the speed. I had a 565 mon block pair side by side to a krell ksa300S and the adcom sounded 90% the same on control and slam ( No Kidding ) On B&W 801. Bryston makes some nice amps too. Im now using ( Soon to Be Replaced ) crown XLS 602 that sounds just great. Its very dry sounding so some recordings sound anemic but then some have much greater sounding lowend. For the money the 565 will do great.
    Von Schweikert VR-8
    Canary Ref. 1 300B monoblocks. 300Bx16

  8. #8
    RIP 2010 scott fitlin's Avatar
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    Amps

    Bryston makes great stuff, the 4B SST would be nice on your bottom!

    Another amp you might want to try is a McIntosh! Yes, Mc! Seek out an older MC 2200 or a MC 2300! You would be surprised at the way these things sound!

  9. #9
    Dang. Amateur speakerdave's Avatar
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    McIntosh Solid State with output transformers

    It's an interesting suggestion. I use the MC2200 to drive my Jubals. It's a very musical amp. I can listen to it for hours while working at the computer, etc, but I know if a plug in my Audio Research VT60 I will stop work and go sit in the sweet spot for who knows how long.
    It is one of the second generation of McIntosh sand amps which have output transformers. The company used to tout them as a method of protecting speakers from solid states amps that can get into thermal runaway, which McIntosh rarely do if ever, but I think they also contribute to the smoothness of sound because they tend to smooth the load impedance. What is sacrificed is the super low output impedance that transformerless amps can have. The damping ratio is rated at 16 to 30 depending on the output tap used. It seems to give solid, competent bass, but tight or punchy I can't really judge because I use a classic tube preamp which I know is a little soft.

    Before I got this amp I used the MC250, which is first generation solid state, also with transformers, for years. The MC2200 is a clear improvement. There is a smaller amp of the same generation called, I think, the MC2125, which you may find more appropriate. With a 10 watt SE amp on top you may not be driving the midrange and treble to a level that would require full power on the lows. Still the reserve power never hurts.

    Regards,

    David

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    Thanks very much for the replies and suggestions!

    One thing that still concerns me is a possible discontinuity in response if the output impedances of the bass and treble amps is very different. Do folks have experience using solid state on the bass crossing over to SET on the treble at around 300 Hz? Does adjustment of overall level of the amps give you enough control to make the transition seamless?

  11. #11
    RIP 2010 scott fitlin's Avatar
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    amp levels

    As long as your active crossover has output level controls that would be where you adjust separate bass/mid/high levels to balance your system!

    If you xover doesnt have this, then you need to use the amplifier front panel gain controls, but if you can its best to do it at the xover and run your amp gains wide open! You get the best signal to noise ratio this way! But, yes, the amps gain controls will be sufficient to balance your setup!

    Funny that the McIntosh MC-2125 was mentioned! Thats exactly the amp Im going to use to run my 16 JBL 2402,s! However, i would think the slightly higher power of the MC-2200 would be somewhat better to run the low end of Kens speakers!

    The output impedance of your SET amp shouldnt be a problem unless the amps output impedance is really high! Say 2 ohms! I think as long as its under an ohm you will be OK.


    BTW, SpeakerDave, I thought about getting an Audio Research to run my tweeters! They are nice sounding amps!

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    Smile

    Scott:

    How is Your setup with 16 2402's, and what is the rest of the setup?

    Really curious,

    Alex.

  13. #13
    RIP 2010 scott fitlin's Avatar
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    My setup

    the 2402,s are mounted in circular arrays of 4, and wired in series parallel. I am currently using two Crown power line 2 amps to run the tweeters. This is 50wpc at 8 ohms! A nominal 12.5 watts per bullet! I cross them over at 7K 18DB Butterworth!

    With the MC I will parallel two arrays per channel, yeilding a nominal impedance of 4 ohms! The MC should sound sweeter on the highs! And this will be a nominal 15 watts per tweeter!

    BTW, It has been my experience with JBL slots and bullets, that they dont like alot of power! They were designed when amp power was much smaller, and the power ratios I have described work really well with these tweeters. No harshness, and they make plenty of sound with this little bit of power!
    Last edited by scott fitlin; 08-27-2003 at 01:20 PM.

  14. #14
    Dang. Amateur speakerdave's Avatar
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    Matching tube and solid state amps

    "One thing that still concerns me is a possible discontinuity in response if the output impedances of the bass and treble amps is very different. Do folks have experience using solid state on the bass crossing over to SET on the treble at around 300 Hz? Does adjustment of overall level of the amps give you enough control to make the transition seamless?"

    Ken:

    I don't know if anyone else can answer these questions for you, and you may be at the point when it's time to start trying things if you can get your hands on some amps. As for trying to predict a match based on some technical description of an amp--I'm doubtful. On that basis you might choose a McIntosh amp with output transformers because it has a damping factor that is close to that of a lot of tube amps. But the result may not be as you predict.

    I would pay more attention to what people have to say about the sonic character of the amps they have experience with. If what you like about your tube amps is their detailed, life-like presentation, then you would want to look for the same qualities in a bass amp, no matter how it is achieved technically. I think in a bass amp these qualities are achieved with high damping factor and high current capability and I would go so far as to make a specific recommendation within your power requirements, and that is the Crown D150 which you can get for about $200, plus or minus $30-40. A lot of people on this forum will say that is too small, and if you agree with them, go for the Crown D300 for about $100 more. I'm sure there are many other suitable amps; these are the ones I'm familiar with.

    As I've said, I use the early McIntosh solid state amps myself, but frankly, I see them only as a decent compromise for full range.

    Scott:

    "BTW, SpeakerDave, I thought about getting an Audio Research to run my tweeters! They are nice sounding amps!"

    Yes, they are very fine, although this particular one I have, the VT60, I wouldn't work very hard into a 4 ohm load. The thing that impresses me, though, is that these JBL speakers can play that song too, besides all the heavy lifting they can do in other applications, and it sounds like Ken is finding that they can go to the SET zone as well.

    Regards,

    David
    Last edited by speakerdave; 08-28-2003 at 12:01 AM.

  15. #15
    RIP 2010 scott fitlin's Avatar
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    I like those old Crowns!

    The D-150A is perfect for mids and an old white face DC-300A happens to sound good on woofers IF its enough power for you! This will give you a punchy low end!

    I like the white face 150A and DC-300A from 78 and 79 the best!

    I dont like the blackface series II D 150,s and 300,s!

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