Bi-Amping 4 Ohm Speakers Using A and B terminals On a Vintage Lower-Powered Integrated Amplifier

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KobayashiSaru

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  • #1
    I recently obtained a pair of JBL HDI-1600 speakers. These are the nicest speakers I've ever owned, and I would like to get the most out of them.

    I have an old Harman-Kardon PM640 integrated amp for listening to my vinyl. It has dual (A & B) speaker outputs, but is only rated for 4 ohm speakers using a single pair at a time. I wouldn't want to try driving two sets of 4 ohm speakers at the same time on this thing. Would I be able to connect one set of terminals to the "A" outputs and the other to the "B" outputs without overloading the amplifier (after removing the bridges of course)? Presumably it wouldn't add any additional load and might even cause less stress on the system, but I don't want to risk my equipment without getting opinions from those more knowledgeable than me. ;)

    Plus, it might be neat to be able to switch one pair off temporarily and just hear the high end or low end.
     
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    Kyuu

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  • #3
    I'm not clear on what you're trying to accomplish here. You can't bi-amp the speakers by connecting it to A and B connections on the same amp. It's still just one amp. Bi-amping is unnecessary anyway unless the amp isn't capable of driving the speaker at your desired volume on its own.

    Just connect the speakers normally to one of the connections and enjoy. If you're worried about damage for some reason, just start with the volume turned all the way down and slowly increase it. You'll hear distortion and clipping long before components start to get damaged.
     
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    AndrewZ

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  • #6
    The theory behind bi-wring is that the tweeter and woofer have separate active impedances, and by putting each on a separate amp, there will be less "interference". I bi-wired with KEF 102.2 speakers and a Rotel amp. I thought I could tell the difference but it was subtle. it wasn't a blind setup so there could have been some placebo going on. Definitely try it out for yourself. Double check your wiring, start at low volume. Do not over drive the amp.
     
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    Kyuu

    Kyuu

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  • #7
    I'll let Peter Aczel of Audio Critic speak for me here:
    The truth is that biamping makes sense in certain cases, even with a passive crossover, but biwiring is pure voodoo.
    If you move one pair of speaker wires to the same terminals where the other pair is connected, absolutely nothing changes electrically. The law of physics that says so is called the superposition principle. In terms of electronics, the superposition theorem states that any number of voltages applied simultaneously to a linear network will result in a current which is the exact sum of the currents that would result if the voltages were applied individually.
    Click to expand...
    The truth is also that it doesn't hurt anything, except your pocketbook for the extra wiring. As long as you're not buying $10,000 crystalline directional unobtainium wires, that's not too bad.
     
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    macosandlinux

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  • #8
    Bi-amp makes sense for specific hardware (amp/speaker) setups. Yours is not one of them - you did not buy a stack of single-channel amps to power some exotic setup/home theater.

    "Good speaker cables" are relative (and snake oil mostly after a certain minimum threshold), just never spent more than 5-10% of your setup cost on them (all your cables). Look at these suckers - $11K for a used pair:

     
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    KobayashiSaru

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  • #9
    Yeah, bi-wiring never made much sense to me when you need to connect both sets of wires to the same single terminals on the amp... But I did wonder if having seperate outputs for the high and low would make a difference. Thanks for the info.


    I always thought things like Monster cables were a scam, but wow, those Nordost Odin cables are flat-out grand larceny.
     
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    yd

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  • #11
    Mono blocks - separate big box, one per channel = the only way to fly :judge:

    Blue Jeans cables will suffice....I am not totally crazy.

    I am kidding but not kidding - my replacement amp for my Jeff Rowland 8t (which used to have a functioning external battery power supply) which is currently 250w per channel stereo will likely be Pass Lab monoblocks (the 260w variant is my practical hunch).
     
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    macosandlinux

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  • #12
    KobayashiSaru said:
    Yeah, bi-wiring never made much sense to me when you need to connect both sets of wires to the same single terminals on the amp... But I did wonder if having seperate outputs for the high and low would make a difference. Thanks for the info.


    I always thought things like Monster cables were a scam, but wow, those Nordost Odin cables are flat-out grand larceny.
    Click to expand...
    Monster Cables were always just overpriced for what you got. Monoprice and others sell equal or better built-quality for a fraction of the cost.
     
    macosandlinux

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  • #13
    yd said:
    Mono blocks - separate big box, one per channel = the only way to fly :judge:

    Blue Jeans cables will suffice....I am not totally crazy.

    I am kidding but not kidding - my replacement amp for my Jeff Rowland 8t (which used to have a functioning external battery power supply) which is currently 250w per channel stereo will likely be Pass Lab monoblocks (the 260w variant is my practical hunch).
    Click to expand...

    Go big or go home, 'ey say :judge:
    Pass Labs is for most the 'golden standard' with amps, but you got to pay for that name (and these totally overpriced chassis), too.
    Have fun!
     
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    AndrewZ

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  • #14
    Kyuu said:
    I'll let Peter Aczel of Audio Critic speak for me here:

    The truth is also that it doesn't hurt anything, except your pocketbook for the extra wiring. As long as you're not buying $10,000 crystalline directional unobtainium wires, that's not too bad.
    Click to expand...
    As someone who actually took electrical engineering classes on active and passive circuits I'm going to say that Peter Aczel has not correctly applied principles here. His principles apply to static resistive loads, and static driving voltages. Speakers have active impedances, and amplifiers have dynamic driving voltages/amps. Although a good amplifier will provide a mostly constant power source. Anyway, as nice a sound bite as that was, it doesn't truly make the case.
     
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    AndrewZ

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  • #15
    macosandlinux said:
    "Good speaker cables" are relative (and snake oil mostly after a certain minimum threshold), just never spent more than 5-10% of your setup cost on them (all your cables). Look at these suckers - $11K for a used pair:

    Click to expand...
    There's one school of thought that says audio signal electrons (alternating current) like the outsisde of their conductor. Therefore, use stranded copper cable, which provides more outer surface area. But don't go overboard on oxygen depleted cables and the like.
     
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    Kyuu

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  • #17
    AndrewZ said:
    As someone who actually took electrical engineering classes on active and passive circuits I'm going to say that Peter Aczel has not correctly applied principles here. His principles apply to static resistive loads, and static driving voltages. Speakers have active impedances, and amplifiers have dynamic driving voltages/amps. Although a good amplifier will provide a mostly constant power source. Anyway, as nice a sound bite as that was, it doesn't truly make the case.
    Click to expand...
    You haven't explained how that results in bi-wiring actually changing anything regarding the electrical circuit. It's also strange that you make a baseless statement regarding using stranded wire due to "audio signal electrons" liking the outside of the conductor. You're referring to the skin effect, but given the short distances and relatively low frequencies involved in an audio circuit, it's basically irrelevant. You can use a straightened out wire hangar as your speaker cable and there will be no audible difference. Stranded wire is still advisable as it's significantly easier to work with.

    Also, defending Monster Cable? lol.
     
    yd

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  • #18
    macosandlinux said:

    Go big or go home, 'ey say :judge:
    Pass Labs is for most the 'golden standard' with amps, but you got to pay for that name (and these totally overpriced chassis), too.
    Have fun!
    Click to expand...
    I am not gonna lie, the 600.8 is a consideration - partially just because it would look 'normal' vs what I have now - aka two large boxes side by side with stuff on top. Now the PL maaay not want stuff on top but I think I could figure something. Do I need that much juice, nope. The sweet spot for their whole amp lineup is the 260.8 which is as much power as i have now. Sadly, they look kinda puny.
     
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  • #20
    Kyuu said:
    You haven't explained how that results in bi-wiring actually changing anything regarding the electrical circuit. It's also strange that you make a baseless statement regarding using stranded wire due to "audio signal electrons" liking the outside of the conductor. You're referring to the skin effect, but given the short distances and relatively low frequencies involved in an audio circuit, it's basically irrelevant. You can use a straightened out wire hangar as your speaker cable and there will be no audible difference. Stranded wire is still advisable as it's significantly easier to work with.

    Also, defending Monster Cable? lol.
    Click to expand...
    OK, so minor correction. When I said bi-wiring I meant bi-amping. I myself don't identify as bi so there you go. One amp on the tweater, the other on the woofer. As I said, the theory is that an amp's power supply can't keep up with changing impedance of the tweeter and woofer. Even if it doesn't sound better, with good speakers, it will sure sound louder :cool:

    Is the skin effect real? Why yes it is. Does it effect the audio on your stereo system? I don't know. I refer the interested reader to the wiki page so they can perform the necessary calculations: Skin Effect.

    Am I defending Monster Cables on price? No I am not. Am I defending Monster Cables on quality? Damn straight. I have some 30+ years old and they are still good. I have had other speaker cables where the insulation turned to goo or the copper "alloy" seriously oxidized.
     
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    Paladin

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  • #21
    Yeah, I have both. I had a friend who worked at a high end electronics (home theater, car audio, etc.) store back in the 90s and he got me some pre-made Monster brand speaker cables, the silly thick ones with pre-terminated banana plugs, for basically no money (he got them via a points system) and they still work great. But then so do the cables I made myself with banana plugs I got from radio shack and a big spool of stranded copper cable. It wasn't the cheapest cable or the most expensive, I wanted the sheath to last and not degrade and ruin the carpet or whatever but now, almost 30 years later, they all still work as well as on day 1. I honestly can't tell the difference.

    I will say that a Monster brand serial cable I got around the same time has been a life saver on a few occasions when it was the only thing that would work to talk to the console port on some weird piece of equipment that had a 25 pin serial port and I needed to connect to my computer on 9 pin. I bought it for IP over serial for Starcraft games (network cards were expensive and not built in to the mainboard yet). It has more than paid off its $40 price (if I remember right).
     
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  • #22
    cogwheel said:
    If it looks too small, just build a little shrine for it so it takes up more space.
    Click to expand...
    You can indeed put components on short little stands 2-4 inches high which would 'help' with the 260.8 but still not the in yer face POWA that the larger units have - and I would be able to slip the bigger ones by the wife because she is used to the size of the current setup but if I ever went down in size, there would be a tricky road to go back up.

    To be fair, having the 260.8s or heck anything, on stands would be probably quite good for air flow. That said, my 8T has been on the floor for 27 years with no drama.
     
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