[aceinc]

I was talking to the missus about flipping the room, and she had an interesting idea instead of a screen/projector, why not a ceiling mounted "cabinet" with a hinged pull down and a flat screen on that.

[aceinc]

Here is a question of a more practical nature.

This is in regards to the GR-Research OB sub, plate amplifier (Rythmik Audio).

On the plate amplifiers, when using "High Level In" how does the signal go to the Mid/Tweeter assembly?

Do I need to build an external crossover/splitter to do low pass to the woofer section, and high pass to the mid/tweeter assembly?

In a perfect world, the High Level In would be an in & out, but either more binding posts would need to be added, or there would need to be two models, one for a sub per speaker, and one for a sub per pair.

Of course I suspect having a high level variable crossover would be an interesting engineering trick.

So if I must have a fixed LF xover can I just do a high pass to the mid/tweeter section and the "crossover" on the plate amp would handle the low pass?

[mlundy57]

If you want to send a full range signal to your main speakers you can connect two pairs of speaker wires to the main speaker binding posts of your power amp. Like bi-wiring. Both pairs of wires must be connected to the same set of binding posts on the amp. If your amp has both A and B speakers, do not connect one pair of wires to A and the other to B unless you want to blow your power amp. The plate amp does not present enough of a load.

If you want to limit the low frequencies going to your main speakers you can install an inline filter. To do this the signal needs to split after the master volume control and you would use the low level inputs on the subwoofer plate amp. To do this you need to be using separates (preamp/pre-pro and power amp). The signal needs to split between the preamp/pre-pro and power amp. If your pre has more than one output one goes to the filter which is then connected to the power amp. The other preamp output is connected to the subwoofer plate amp.  If your pre only has one output the filter can be built with a by-pass leg. The leg that goes through the filter is connected to the power amp while the signal that by-passes the filter is connected to the subs plate amp. The filter consists of a single capacitor. The caps value is determined by the frequency you to roll off at and the input impedance of your power amp.

[bdp24]

Here is a question of a more practical nature.

This is in regards to the GR-Research OB sub, plate amplifier (Rythmik Audio).

On the plate amplifiers, when using "High Level In" how does the signal go to the Mid/Tweeter assembly?

Do I need to build an external crossover/splitter to do low pass to the woofer section, and high pass to the mid/tweeter assembly?

In a perfect world, the High Level In would be an in & out, but either more binding posts would need to be added, or there would need to be two models, one for a sub per speaker, and one for a sub per pair.

Of course I suspect having a high level variable crossover would be an interesting engineering trick.

So if I must have a fixed LF xover can I just do a high pass to the mid/tweeter section and the "crossover" on the plate amp would handle the low pass?

It can be confusing, but doesn't have to. If you get the PEQ3 version of the Rythmik plate amp, it has a high pass filtered output that provides an 80Hz crossover for main speakers. You send the signal from your pre-amp (or tape out jacks on an integrated amp or receiver) to the plate amp, that amp powers the subs, and the high pass filtered output goes to your speakers power amp (or back to your integrated amp or receivers tape in jacks). Very simple. Purists disapprove of doing it this way, as the high pass filtering is done in the Rythmik via Opamps, which lack audiophile approval and credibility. The way they do filtering is via a passive x/o containing only a single capacitor, or an outboard electronic x/o. Good analog ones start at about a grand, but digital ones are available for only a couple hundred.

[Danny Richie]

Here is a question of a more practical nature.

This is in regards to the GR-Research OB sub, plate amplifier (Rythmik Audio).

On the plate amplifiers, when using "High Level In" how does the signal go to the Mid/Tweeter assembly?

Do I need to build an external crossover/splitter to do low pass to the woofer section, and high pass to the mid/tweeter assembly?

In a perfect world, the High Level In would be an in & out, but either more binding posts would need to be added, or there would need to be two models, one for a sub per speaker, and one for a sub per pair.

Of course I suspect having a high level variable crossover would be an interesting engineering trick.

So if I must have a fixed LF xover can I just do a high pass to the mid/tweeter section and the "crossover" on the plate amp would handle the low pass?

To use the speaker level inputs you just parallel them with your speakers. No high pass filters are involved this way. So you main speakers get a full range signal.

Some amps do add a high pass filter but using it is not recommended.

For filtering off the lows we recommend doing so prior to amplification using high quality inline coupling caps.

[aceinc]

Thanks for the tips, however, I do not have the ability to (easily) send line in to the sub, so my intention was to treat these as full range speakers and only send speaker level signal to the "speaker system." I will need to split that signal at the speaker. I would rather not run full range to the mid/tweeter in order to reduce amplifier load. It would also reduce the amount of work the mid/tweeter section would need to do.

My thought was a simple cap at say 199 uf, as a high pass filter to the mid/tweeter section and let the plate amp's built in (hopefully) low pass filter block the high frequencies to the woofer assembly. This should give me 6 db down at 50 hz. A steeper slope might be better. Perhaps a third order filter which would reduce the the 50hz point by 18 ohms. Unfortunately the online calculators want to know the impedance of the Low frequency assembly and I do not know what to plug in for that number.

I guess what I am saying is I need professional help (my wife has been saying that for years).

[Danny Richie]

Thanks for the tips, however, I do not have the ability to (easily) send line in to the sub, so my intention was to treat these as full range speakers and only send speaker level signal to the "speaker system." I will need to split that signal at the speaker. I would rather not run full range to the mid/tweeter in order to reduce amplifier load. It would also reduce the amount of work the mid/tweeter section would need to do.

My thought was a simple cap at say 199 uf, as a high pass filter to the mid/tweeter section and let the plate amp's built in (hopefully) low pass filter block the high frequencies to the woofer assembly. This should give me 6 db down at 50 hz. A steeper slope might be better. Perhaps a third order filter which would reduce the the 50hz point by 18 ohms. Unfortunately the online calculators want to know the impedance of the Low frequency assembly and I do not know what to plug in for that number.

I guess what I am saying is I need professional help (my wife has been saying that for years).

Yes, you can do something like that, but that is a pretty big cap to put inline with your mids. A cap value that large in reasonable quality gets pricey. The entire signal to your mids will pass through that cap.

[Captainhemo]

Thanks for the tips, however, I do not have the ability to (easily) send line in to the sub, so my intention was to treat these as full range speakers and only send speaker level signal to the "speaker system." I will need to split that signal at the speaker. I would rather not run full range to the mid/tweeter in order to reduce amplifier load. It would also reduce the amount of work the mid/tweeter section would need to do.

and,  if I'm reding this right,  splitting the high level signal (after the amp(s) ),  will not reduce  the load on it/them.  To do so, you'd need to  filter before the amp at line level ( high pass to amp,  full range to subs)

jay

[aceinc]

Here is a question for people more knowledgeable than me;

Which is worse, SQ wise, sending low frequency signals to the mid/tweet assembly causing the mid woofers to try to reproduce sounds they can't, or to introduce crossover component(s)?

Based on my limited experience, and some reading I have done, sending unattenuated LF signal to the mid/tweet assembly would do at least two things that might not be good. 1) Cause the midbass woofers to flap in the breeze, introducing doppler distortion. 2) Reduce the power handling due to excursion limits being reached.

On the other side of the equation, I don't know the negative impact of adding the crossover component(s).

[Danny Richie]

Here is a question for people more knowledgeable than me;

Which is worse, SQ wise, sending low frequency signals to the mid/tweet assembly causing the mid woofers to try to reproduce sounds they can't, or to introduce crossover component(s)?

Based on my limited experience, and some reading I have done, sending unattenuated LF signal to the mid/tweet assembly would do at least two things that might not be good. 1) Cause the midbass woofers to flap in the breeze, introducing doppler distortion. 2) Reduce the power handling due to excursion limits being reached.

On the other side of the equation, I don't know the negative impact of adding the crossover component(s).

The key to great sound quality is settling time. And this is often completely overlooked. How fast can you get the drivers to return to rest is what it really is all about.

And relieving a driver of just the first octave really helps. Relieving it of the first two octaves helps a lot.

And on drivers playing down to the rock bottom, use servo control. 

Regarding the crossover components, if good quality parts are used they really don't have the negative effect that a lot of people think they do.

[Captainhemo]

The key to great sound quality is settling time. And this is often completely overlooked. How fast can you get the drivers to return to rest is what it really is all about.

And relieving a driver of just the first octave really helps. Relieving it of the first two octaves helps a lot.

And on drivers playing down to the rock bottom, use servo control. 

Regarding the crossover components, if good quality parts are used they really don't have the negative effect that a lot of people think they do.

And  not only  are  those   good crossover parts relatively  costly, they are big so  you need some real estate !
Here's roughly a 100uF groupof the new Clarity  CMR series



jay

[aceinc]

Those are some impressive Caps. I think I can find some that are still good, but not so voluminous.

[bdp24]

Those are some impressive Caps. I think I can find some that are still good, but not so voluminous.

Damnit, now I gotta dig out my dictionary again.

[Captainhemo]

Those are some impressive Caps. I think I can find some that are still good, but not so voluminous.

The Soniccap G1's offer great value and they are not so   "voluminous"  !

Funny guy eic   

jay