How to determine if my RTi4's are blown?

louhamilton

Okay, I recently upgraded my system to include a Denon 3808CI ,PS3, and SVS PB12-NSD.

After watching Hitman, I noticed the mids in the RTi4's are a little muddy today. Sort of scratchy and not tight. I used the Denon to calculate all settings. The only thing I changed was the x-over from 40Hz to 80Hz.

Not sure what else I can say about it except that I typically listen at -40 to -30, but I bumped up Hitman to -20 just to really "feel" the movie.

Erik Tracy

Lou,
Wow - I'm surprised that you may have blown your RTI4s.

The Denon 3808CI is rated the same as my Yamaha RX-V1800 (130watts/channel - but measured at 103watts/channel 5 channels driven).

Not sure what -20 'translates' to in relation to output, though.

Still, to drive a speaker to damage would mean overdriving the amp into distortion and causing heat/damage in the drivers.

I've driven my RTI4s pretty hard and loud, but mostly for music. I guess that means less dynamics than movie effects - maybe that's the potential problem - a short BIG spike in spl/dynamics during the movie?

Loudest I drove my RTI4s (just from the avr and before using the Carver M-1.0t) during a movie was "Fellowship of the Ring" the scene with the Balrog vs Gandalf....WAY loud! But the RTI4s sounded clean w/ no damage.

Keep us posted....
Erik

zingo

It's possible I guess that you damaged the speakers. Receivers clip easier than a dedicated amp, and thus can cause damage easier and at a lower volume. 40hz is way too low of an x-over settings for those speakers or most speakers, and moving that up was a good idea. Push lightly on the driver and see if you hear a scratching sound.

Erik, -20 refers to 20 db below the reference volume on the receiver. It's harder to damage the RTi4 with your Carver than a receiver for the reasons stated above. A dedicated amp provides "clean" power so to speak.

louhamilton

UPDATE:

It seems to be related to only music streamed through the PS3. I hooked up my D-Link DSM-320 with an optical cable and the music is night and day. I need to play around with the PS3 and see if there are any settings that can be changed.

Erik Tracy

Lou,
Glad to read that the RTI4s are not blown! The PS3 does have some settings for "music" (sampling rate, decoding, and bit mapping) - hope you find the right settings.

This may go off topic here, but would like to learn more.

I kinda sorta maybe understand the reference db thingy, but dbs are not dbs - depends on the units.

Check out the chart here at the bottom:
http://www.allaboutcircuits.com/vol_3/chpt_1/6.html

If I understand correctly, -40dbm (this is where I think I need clarification on the exact db units being inferred when using db to refer to *power*) is the same as 0.002 watts.

And even if Lou 'bumped' up the volume to -20dbm - that is still less than 1 watt of power!

Or, maybe the unit isn't dbm but something else like dbV or dbu or dbFS??
http://www.sizes.com/units/decibel.htm

Now my head hurts!

If someone has a good link to point me to so I can sort db vs power out - I'll be quiet and study

Ron Temple

Dolby reference level is 85dbs average and allowing peaks of 20dbs in the main channels and 30dbs for LFE. If you calibrate your AVR/pre-pro to 85dbs @ - 0, then that's reference level. Most AVRs can't do it without clipping. It's all relative, my reference point is -15.