[Danny Richie]

If I read you correctly, the kit will not include the high pass filter, and you are suggesting a 6 dB/oct inline R-C high pass filter between the preamp out and the amplifier input. With the R being the amp input impedance.

What is the Low pass filter slope in the servo amp,  6dB or 12 dB? I know its frequency is variable.

That high pass filter will not be a RC (resistor and cap) type filter. That would be a second order filter. And I can't include it as part of the kit because it is dependent on the input impedance of the amp used with them. And that can vary by a lot.

However, if you can tell me what the input impedance of your amp is then I can recommend the appropriate cap value for you. 

The low pass filters on the servo amps are second order.

[rak313]

That high pass filter will not be a RC (resistor and cap) type filter. That would be a second order filter. And I can't include it as part of the kit because it is dependent on the input impedance of the amp used with them. And that can vary by a lot.

However, if you can tell me what the input impedance of your amp is then I can recommend the appropriate cap value for you. 

The low pass filters on the servo amps are second order.

I remain confused.  The high pass filter is made from an inline cap and what other components (are they in the amp)?  Isn't the input impedance of an amp is generally just a resistance? (I'm talking transistor amps, not tube amps.)

I was assuming the high pass filter was the inline cap and the (resistive) amp input impedance, thus  I assumed an RC filter.

I don't know why you say that a single cap, RC is 2nd order (assuming its being driven by a voltage source). It takes 2 energy storing components (L, or C) to get a second order filter. 

[mlundy57]

Here's a picture of the inline filter Danny posted awhile back. This one is a little fancier in that it has a bypass as well as the filter.



There is a discussion of this filter in the LGK 1.0 thread http://www.audiocircle.com/index.php?topic=124657.20 . Start with reply #21

The second order filter is in the subwoofer plate amp. 

[Danny Richie]

I remain confused.  The high pass filter is made from an inline cap and what other components (are they in the amp)?  Isn't the input impedance of an amp is generally just a resistance? (I'm talking transistor amps, not tube amps.)

I was assuming the high pass filter was the inline cap and the (resistive) amp input impedance, thus  I assumed an RC filter.

I don't know why you say that a single cap, RC is 2nd order (assuming its being driven by a voltage source). It takes 2 energy storing components (L, or C) to get a second order filter.

I am just talking about the device itself.

For instance the FMod filters are second order. http://www.parts-express.com/harrison-labs-fmod-inline-crossover-pair-70-hz-high-pass-rca--266-272

They have an inline cap and a shunt resistor.

What I am talking about is just a cap and it makes a first order roll off.

And the reason that the single cap will result in a second order roll off in this application is that the drivers have a natural first order roll off in an open baffle. So if you add a first order electrical filter to it then you get a second order acoustic roll off.

And the second order filter on the servo amp allows for a matching acoustic slope.

[iamediam]

Danny,

Can the high pass filter be put on the speaker level outputs of the amp instead? For all digital configurations such as integrated usb dac/amps, or receivers.

[Danny Richie]

Danny,

Can the high pass filter be put on the speaker level outputs of the amp instead? For all digital configurations such as integrated usb dac/amps, or receivers.

You can, but the cap value gets much larger, much more expensive, and doesn't sounds near as good.

[rak313]

...
And the reason that the single cap will result in a second order roll off in this application is that the drivers have a natural first order roll off in an open baffle. So if you add a first order electrical filter to it then you get a second order acoustic roll off.

And the second order filter on the servo amp allows for a matching acoustic slope.

Got it.  Thanks

[bdp24]

Danny, on a related issue, could you explain how you got a low-pass x/o frequency of 180Hz (or was it 280Hz?) for the OB woofers in the Super-V using the controls on the A370 amp? As we know, the panel reads up to only 120Hz.

[Danny Richie]

Danny, on a related issue, could you explain how you got a low-pass x/o frequency of 180Hz (or was it 280Hz?) for the OB woofers in the Super-V using the controls on the A370 amp? As we know, the panel reads up to only 120Hz.

Numerical values on the dial indicates electrical attenuation and not acoustic output. And crossover points are where drivers are 6db down in output. So to cross in the 180Hz range the dial is usually set in the 90Hz range.

[bdp24]

Got it, thanks.

[Tyson]

Numerical values on the dial indicates electrical attenuation and not acoustic output. And crossover points are where drivers are 6db down in output. So to cross in the 180Hz range the dial is usually set in the 90Hz range.

Wouldn't this be true of ANY speaker level crossover parts?  Seems like a few passive parts after your preamp and before your amp(s) would beat a speaker level crossover.  More expensive, sure, since you'd need 2 amps, but when did that ever stop crazy audiophiles?

[HAL]

That was an excellent way to biamp my Maggy IIB's in the '80s.  Passive XO between the preamp and two Hafler DH220 amps.

[bdp24]

Wouldn't this be true of ANY speaker level crossover parts?  Seems like a few passive parts after your preamp and before your amp(s) would beat a speaker level crossover.  More expensive, sure, since you'd need 2 amps, but when did that ever stop crazy audiophiles?

My question (and Danny's answer) was about the low-pass x/o in the Rythmik Servo amp, not speaker level cross-overs. With that amp powering the subwoofer driver(s), only one stereo amp (or two mono's, of course) and a high-pass cross-over of some type (active or passive line-level) is needed for the pair of loudspeakers.

[ebag4]

I also thought about just using 9 of the LGK's below the MMTMM, but I am not sure I can get that sensitivity up to the 95db range in those lower regions.

Danny, have you been able to determine what the sensitivity will be with the MMTMM and the 9 LGKs below?

What kind of volume can these setups (MMTMM with 9 LGKs and MMTMM) be expected to play to without strain?

Thanks,
Ed

[Danny Richie]

Danny, have you been able to determine what the sensitivity will be with the MMTMM and the 9 LGKs below?

What kind of volume can these setups (MMTMM with 9 LGKs and MMTMM) be expected to play to without strain?

Thanks,
Ed

The 9 LGK's below should hit 94db levels. But the range will be limited each way, so it may work out well. The woofers in the MMTMM will roll into them and the subs being used will roll into them on the other side. I think it will work out pretty well. It will all be in how I design the crossover and how the high pass is handled to those drivers.

[ebag4]

The 9 LGK's below should hit 94db levels. But the range will be limited each way, so it may work out well. The woofers in the MMTMM will roll into them and the subs being used will roll into them on the other side. I think it will work out pretty well. It will all be in how I design the crossover and how the high pass is handled to those drivers.

Thanks Danny, I believe you are referencing the sensitivity above. What kind of volume can these setups (MMTMM with 9 LGKs and MMTMM) be expected to play to without strain?  My V1s hit 105dB pretty easily in my small room (not that I do that often) but they will hit concert levels and above, can we expect the MMTMM be able to do this?

Also, something you kind of hit on earlier in this thread, a 200 Hz wave is approximately 6' long if what I have read is accurate, does that mean I actually have feet to play with as opposed to inches between the bass section and the MMTMM section?  The reason I ask is because I am now considering going with a separate bass stack and MMTMM tower.  If I choose to do that with the MMTMM tower taking over at 200Hz, how far apart can they be?

Thanks,
Ed

[Danny Richie]

Thanks Danny, I believe you are referencing the sensitivity above. What kind of volume can these setups (MMTMM with 9 LGKs and MMTMM) be expected to play to without strain?  My V1s hit 105dB pretty easily in my small room (not that I do that often) but they will hit concert levels and above, can we expect the MMTMM be able to do this?

Also, something you kind of hit on earlier in this thread, a 200 Hz wave is approximately 6' long if what I have read is accurate, does that mean I actually have feet to play with as opposed to inches between the bass section and the MMTMM section?  The reason I ask is because I am now considering going with a separate bass stack and MMTMM tower.  If I choose to do that with the MMTMM tower taking over at 200Hz, how far apart can they be?

Thanks,
Ed

I think you'll be able to touch those levels just fine if they are high passed with a filter.

And with a 200Hz crossover point you really have about three feet of distance to work with to avoid problems.

[ebag4]

Got it, thanks Danny.

If looking for the best sounding solution in conjunction with a pair of 12" servo sub what is your recommendation with regard to this solution, the MMTMM or the MMTMM with 9 LGKs below?

Best,
Ed

[Danny Richie]

Got it, thanks Danny.

If looking for the best sounding solution in conjunction with a pair of 12" servo sub what is your recommendation with regard to this solution, the MMTMM or the MMTMM with 9 LGKs below?

Best,
Ed

Using the 9 LGK's  below will extend the lower end to a crossover point of around 150Hz or less. I am looking forward to it myself.

[ebag4]

Danny, you certainly know how to keep a would-be speaker builder in suspense  .  Looking forward to the flat-pack and final pricing information and availability.

In the mean time, does the bottom need to be solid on the MMTMM?  I am assuming so since this is apparently the configuration in which you tested it.

What will be the optimum height for this speaker, NEO 3 at ear level, higher than ear level, any tilt required?

Thanks,
Ed