Amp selection for RTi10s....Need help

[Methodical]

Okay, I know you are clear, but let's try to be even clearer. If I understood correctly you are saying:

1) The towers are now set to small.
2) XO at 80 Hz
3) The phase switch pos. does make a difference.

If you can hear a difference by flipping the phase switch with XO at 80 Hz, you are getting bass cancellation. The cancellation effect will be much more audible if you had the mains set to large because the mains will then be getting full range, i.e. down to 20 Hz and below. Since the RTi10 can reproduce 20 Hz, it will cancel the subwoofer's bass if the signals are not in phase.

Two questions:

1) Have you tried setting the mains to large, and flip the 505's phase switch back and forth and see if you could hear a difference?

Yes I have and yes there was some audible difference. It seemed like the sub got louder or deeper/bassier (if that's the correct word)

2) How did the towers sound if you set the mains to large, or listen in pure direct mode, with the 505 power turn off completely.

I tried this and the mains actually sounded pretty good and tight with the EQ off. I listened to the music in Pure Direct with the eq on and off. I need to do some serious EQ tweeking as I have them set way to loud. The music, with the EQ on with my current settings, although louder, was not as clean sounding as with the EQ off. I just found some info on the web that explains each frequency range and the affects it has on music/movies, therefore, I will go back and tweek the EQ settings some more.

The thing is, my Veritas are less efficient than your RTi's, and I have no problem with bass when using the 3805 on its own. The 3805 is not as powerful as a 150WPC power amplifier but it should have no trouble driving a pair of RTi10, especially in two channel music.

One more thing to check, make sure you L&R channels are connected in phase. That is, from the amp output to the speaker terminals, red to red, black to black, for both L&R channels. If not, you will get bass cancellation between the two tower speakers. Good luck!

Yes, they are connected correctly.

My current set up know is below.

1) The towers are now set to small.
2) XO at 80 Hz - LFE+Main
3) Phase switch at 180

By the way, I purchased the SPL and for experimentation, I listened to CDs at a -15 as you suggested in pure direct mode with EQ on and off and got readings, which varied of course, from 100-115 from what I saw. This is the db level of the music right. How can I use this SPL to determine if I am getting bass cancellation other by using my ear. How can I use the SPL, if possible, to setup my system.

Thanks for any help

 

[PENG]

My current set up know is below.

1) The towers are now set to small.
2) XO at 80 Hz - LFE+Main
3) Phase switch at 180

By the way, I purchased the SPL and for experimentation, I listened to CDs at a -15 as you suggested in pure direct mode with EQ on and off and got readings, which varied of course, from 100-115 from what I saw. This is the db level of the music right. How can I use this SPL to determine if I am getting bass cancellation other by using my ear. How can I use the SPL, if possible, to setup my system.

Thanks for any help

1) With tower set to small, LFE+Main is not valid, the 3805 won't allow you to do it, please double check.

2) Check to see if you are getting interference (cancellation) between the towers and the sub:

With tower set to large, sub set to LFE+MAIN, set your meter to C weighting, slow, play a test tone of say, 40Hz at 80 to 85 dB SPL with the towers only; then with both towers and the 505. If the SPL drops significantly with the 505 turned on then you are getting some cancellation at that frequency. Repeat the same for other low frequencies between 20 to 60 Hz and see if you get dips in other frequencies as well. This is one way I can think of, I am sure there are other ways to do it.

3) To use the SPL meter to set up you system, you also need to use the receiver's internally generated test tones or a 3rd party test disc such as one of those by Avia, Ovation, or others. The following links could be helpful if you don't mind do some readings:

http://www.cnet.com.au/hometheatre/audio/0,239025973,240062282,00.htm#6
http://www.audioholics.com/techtips/setup/loudspeakers/subwoofercalibration.php

I also found an article by Pioneer, that talks about bass cancellation:

http://www.aes.org/technical/documentDownloads.cfm?docID=248

You may also want to visit www.svsubwoofers.com, there are lots of useful bass related information.

Have fun!

 

[Methodical]

1) With tower set to small, LFE+Main is not valid, the 3805 won't allow you to do it, please double check.

Yes, I do understand this. I just leave it set this way so that when I make the switch between large and small I only have to make just one change - setting the mains to large - and not 2 changes.

3)... The following links could be helpful if you don't mind do some readings:

http://www.cnet.com.au/hometheatre/audio/0,239025973,240062282,00.htm#6
http://www.audioholics.com/techtips/setup/loudspeakers/subwoofercalibration.php

I also found an article by Pioneer, that talks about bass cancellation:

http://www.aes.org/technical/documentDownloads.cfm?docID=248

You may also want to visit www.svsubwoofers.com, there are lots of useful bass related information.

Have fun!

No, I don't mind the readings. This way I can learn and understand better and ask more relevant ?s. As matter of fact, I appreciate you providing me with this info.

Thanks. I am in the process of obtaining the Test CD.

 

[Methodical]

Update: Got 2 Behringer A500 amps and I am very pleased.

 

[AVRat]

Glad to hear (pun intended)! They should get those 10s rockin'!!

 

[PENG]

Update: Got 2 Behringer A500 amps and I am very pleased.

Good to know that a relatively low cost solution works out well for you. I hope you can still have fun with setting things up with the SPL meter!

 

[Methodical]

Thanks fellas. I will continue to experiment and test. Waiting for that test tone CD.