Home theater amp advice...

[lovinthehd]

Really

There does seem to be a lot of mystery with the limited measurements you have....

 

[PENG]

Maybe he should have his speakers measured!

Slight problem for a regular multimeter to even just to measure the "DC" resistance though, assuming the schematic is accurate. The LF section will measure very high value, in mega ohms anyway, due to that gigantic series capacitor. It can be done, but need a little more work. I am really quite sure this is one case where probably some DIY individual took some measurements, posted that curve and then it kept getting circulate around, with or without editing and because those big woofers and mid woofers do draw a lot of current, killed a bunch of amps, and awarded the killer title, and then in turns make the impossible 0.8 ohm dip look credible.

To me, if Infinity specified 4-6 ohms nominal, that just backs up what the schematic shows is believable. It would have been totally and utterly insane for the Infinity designers/engineers the Kappa series to have dips below one ohm at more than one place, and with a curve like the one circulated, yet still claim 4-6 ohms nominal. In fact, that would be more than insane, more like false advertisement to the extreme.

 

[lovinthehd]

Didn't mean with a multimeter....was thinking more about something like the Dayton DATS gear.

 

[Verdinut]

I did the calculations for with and without the 1 ohm resistor, results are as follow.
Would you not consider using a subwoofer with XO set to 80 Hz? That would allow you to avoid the most serious dip between 20 and 80 Hz. In addition, you can bi-amp at the same time, so the mid/high section will be isolated from the influence of the big woofer. Again, if you do that, there are all kinds of amplifiers that can do a good job for you. I bet those speakers will sound significantly nicer that way.

I agree with you for the wise recommendation to get a good subwoofer with XO set to 80 Hz.
IMO, that would improve the transient response of the speakers as a series resistance, as is the case here, defeats to a great extent the damping action of any amplifier.

 

[03kbredfire]

I agree with you for the wise recommendation to get a good subwoofer with XO set to 80 Hz.
IMO, that would improve the transient response of the speakers as a series resistance, as is the case here, defeats to a great extent the damping action of any amplifier.

I have a good subwoofer and I do have it crossed at 60. I have chosen to omit the mains from the crossover. They run full range. The problem really is that if I run the sub down, the speakers on their own are kind of anemic sounding which makes little sense other than the feeling that the switch is impairing the speakers from running at their best. Mind you, this is with the use of receiver providing the power at this time. I have, as stated in first portion of thread, a new pre/pro with a pair of JC1's to allow the mains to run with switch in the "extended" mode which bypasses the resistor which I feel neuters the speakers at this time.

 

[lovinthehd]

I have a good subwoofer and I do have it crossed at 60. I have chosen to omit the mains from the crossover. They run full range. The problem really is that if I run the sub down, the speakers on their own are kind of anemic sounding which makes little sense other than the feeling that the switch is impairing the speakers from running at their best. Mind you, this is with the use of receiver providing the power at this time. I have, as stated in first portion of thread, a new pre/pro with a pair of JC1's to allow the mains to run with switch in the "extended" mode which bypasses the resistor which I feel neuters the speakers at this time.

Crossed or just a lpf set at 60?

 

[Verdinut]

I have a good subwoofer and I do have it crossed at 60. I have chosen to omit the mains from the crossover. They run full range. The problem really is that if I run the sub down, the speakers on their own are kind of anemic sounding which makes little sense other than the feeling that the switch is impairing the speakers from running at their best. Mind you, this is with the use of receiver providing the power at this time. I have, as stated in first portion of thread, a new pre/pro with a pair of JC1's to allow the mains to run with switch in the "extended" mode which bypasses the resistor which I feel neuters the speakers at this time.

Have you tried to set the crossover to 80 Hz to see if you can hear an improvement in the bass tightness?

 

[PENG]

Didn't mean with a multimeter....was thinking more about something like the Dayton DATS gear.

I know, that's for the OP, just in case. While searching for info on those 9 Kappa, I was amazed to learn that so many people in the DIY community seem to believe in the below 1 ohm dip(s) claims, when it was so obvious from the available schematic that even if the two parallel woofer coils have 0 resistance and inductance (we all know that is impossible, pure 12 AWG wire has 1.588 ohms per 1000 ft),they should not ignore the significant impedance of that 2000 uf cap in the 20-80 Hz range. And as @AcuDefTechGuy pointed out, even his Yamaha AVR managed to survive for so long, sure it would shutdown if the resistor was not switched in, but he could have back the volume off by 1-2 dB (a little more if necessary) and have the resistor out for sure. The fact is, why didn't it kill the AVR if the below 2 ohms dips were real, let alone the 0.8 ohm one..

 

[PENG]

Fair question. The crossover for the woofers are reportedly at 80Hz. So if I crossed at 80 then I would essentially be shutting off 4 12" drivers. At that point I should not have these speakers and just get bookshelves. With the new Yamaha pre/pro, I can adjust crossover between speakers. I do not remember what the lowest crossover point is but I could try that. I have currently bypassed the crossover function and just let it eat so to speak. I listen to songs like Boz Scaggs "Thanks to you" or Chris Jones "Long after you're gone" to get a sense of overall tonality. Love the sound with mains running full range. I feel like I would be neutering the speakers by utilizing a XO.

Crossover is not a brick wall. If you set XO to 80 Hz on the Yamaha receiver, you will still get some decent output down to 40 Hz. IMO, you can do much better with a good subwoofer and forget about the 2X12" ancient woofers in the Kappa 9. Also, to be very clear, the schematic shows exactly how that 1 ohm 50 W resistor is wired so you can see that it absolutely will not affect the mid and high frequencies, say from 200 Hz and up. The crossover for the woofers are not just "reportedly at 80 Hz..", it is specified by Infinity to be 80 Hz and should be verifiable because they published the schematic diagram, complete with values of each and every component.

 

[AcuDefTechGuy]

Set speakers to small and XO to 120Hz. Should be good to go.

 

[03kbredfire]

Set speakers to small and XO to 120Hz. Should be good to go.

Well, I tried that tonight and the system sounded like the neutered mess that I expected that it might. Returned it to large and allowed the 4 ancient 12's to perform their magic again. Now I remember why I am not parting with these. Beautiful. I am sure it will be even better when I can hook up the Parasound JC1's and let them eat. One thing I happened to do by accident that has netted good results is place the JC1 on top of the sub for now to save floor space in the interim and the system sounds better. I have to assume that the extra weight on the enclosure has helped ground the sub better and provide a dampener for what was otherwise loss of strength through normal vibration. Either way, once placing the amps in a permanent home, I may add some weight to the top of the sub to maintain this same effect. Congrats for now to the RX-V2700.

 

[03kbredfire]

I would like to attempt to put thread back on track a bit. The OP was to gain help with a multi channel amp, now that I have purchased the JC1's to provide what I hope will be ample power for my difficult to drive speakers. I like the mono's because of the channel separation. I liked and chose the JC1's due to their very high damping factor, very high slew rate and excellent signal to noise ratio. The question of a suitable multi channel would at first seem easy as Parasound makes a near matching 5 channel. The problem I have is cost of unit, which is higher than several other offering available and their lack of modular design like so many others have. The channel separation is much reduced by comparison to others; Anthem, ATI, monolith and Emotiva. Most of these incorporate a modular design which is great at channel separation. The other concern is of the linearity from one design amp to another. Meaning when turning up they would act differently from one another. Any thoughts on this original concern?

 

[Verdinut]

The crossover for the woofers are not just "reportedly at 80 Hz..", it is specified by Infinity to be 80 Hz and should be verifiable because they published the schematic diagram, complete with values of each and every component.

Due to the fact that the impedance of drivers varies with frequency, unless you can also test the woofers specs apart from the published schematic diagram and component values, you will not be able to ascertain the exact crossover frequency.

 

[PENG]

Due to the fact that the impedance of drivers varies with frequency, unless you can also test the woofers specs apart from the published schematic diagram and component values, you will not be able to ascertain the exact crossover frequency.

I am not sure if I understood your point. You can determine the crossover point of a crossover network by types and orders. It has nothing to do with the drivers. A Butterworth 3 rd filter is still a Butterworth 3 rd order, input a signal, measure the output, plot the graph and you'll see the crossover point based on the associated definitions. You and I can both set our mains to 80 Hz in our AVRs (I know you use active XO) and we can have different drivers/speakers, yet we still say our XO were set to 80 Hz.

If you meant the overall impedance of the speakers, then of course it is affected by the driver's impedance vs frequency characteristics. My assertion is that even if you ignore/don't care about the woofer's impedance, iow consider them zero ohm, the series cap's impedance is 2.65 ohms at 30 Hz, and the parallel inductors without the 1 ohm resistor switched in, is 1.285 ohms. As frequency goes up, the cap's impedance will drop and the inductor's will increase. That's all I am saying..

 

[Verdinut]

If you meant the overall impedance of the speakers, then of course it is affected by the driver's impedance vs frequency characteristics. My assertion is that even if you ignore/don't care about the woofer's impedance, iow consider them zero ohm, the series cap's impedance is 2.65 ohms at 30 Hz, and the parallel inductors without the 1 ohm resistor switched in, is 1.285 ohms. As frequency goes up, the cap's impedance will drop and the inductor's will increase. That's all I am saying..

I just meant that, when you design a passive crossover, no matter the crossover or filter type, you have to calculate the values of its components based on the exact impedance of each driver at the required filter frequency. That's the only way to design a crossover for a smooth transition from one driver to the other and at the right frequency.

 

[PENG]

I just meant that, when you design a passive crossover, no matter the crossover or filter type, you have to calculate the values of its components based on the exact impedance of each driver at the required filter frequency. That's the only way to design a crossover for a smooth transition from one driver to the other and at the right frequency.

Agreed.

 

[M Code]

Note that when a single frequency is noted for an AVR or surround pre-amp/processor bass manager X-over filter, be it a high pass or low pass filter this is specified @ -3dB point.. The actual audible effect depends upon the roll-off curve be it 12dB/Octave, 18dB or 24dB...

Just my $0.02...

 

[Verdinut]

In a well designed passive crossover, no matter the frequency or filter slope or type, there should not be any audible effect as the frequency response curve is relatively smooth around the XO set filter frequency.