Biamping RTi's

rs159

Been thinking of biamping some RTi's, either the RTi70, RTi8, or RTi6. Of course were talking stuff that for all intents and purposes doesn't exist yet, but just to throw an idea out there...

Now, im talking bypassing the passive xovers, and using an external active crossover

1) What is a good active crossover for home use? I don't mind if its pro, as long as it's not something ugly made to fit under a seat in a car... It would be nice to have a delay to compensate for the non-time aligned baffle, keywords being "nice to have".

2) Do the xovers in the RTi's mentioned above (current, and if anybody knows..new) have any "band aids", such as response shaping circuits, in addition to the straight hp/lp?

3) Of course this just makes things a complex mess, but...would it be worth it? Im a logical type person, so things that are logically better, like active crossovers, appeal to me.

Just so I don't have to type this later; "Russ, you're right"

dorokusai

RS - You have some car audio ideas in your head that just do not migrate into home audio. I know very little about car audio, so I am not sure if thats what you actually meant. Bi-Amping is your main project question right? Where have you been? We have missed you over here.

1)No external crossover needed in home audio. If you want to bi-amp, you just use another amplifier, running of the pre-outputs. You may, with an AVR, use some filter(crossover) settings to adjust your system pre-outs, for calibration.

2)The crossovers in the Polk home series and most home audio are passive. No would be the answer for the RTi series question. All crossovers are "noise shaping" in a off , but not actively, or custom. Do you mean in a equalizer way? You may change your crossovers beyond manufacturers specs, but that is manual.

3)Is it worth it? Only you can decide that. I don't have the funds to handle that load for my systems. Is it a good idea? Sure, you can never have too much power. The loudspeaker is rated for power, and the more dynamic, and specific power you can give it....the better in theory, it should perform.

Does this help?

EDIT: Sorry, just read a word in your question....I honestly don't know of a external crossover available for the home application. An EQ is maybe what you mean? Or maybe what you want, but why would you?

rs159

Actually, i wasn't thinking of car audio at all. Its not unheard of to use active crossovers at home:

(Sorry for ripping from websites, but if I tried to type this out myself it would be way too wordy and unorganized)

"Some people choose to use an electronic crossover between their preamplifier and pair of power amps. This active crossover pre-filters the audio signal at a low-voltage level and sends only predetermined bass frequencies to the bass amp and high frequencies to the tweeter amp. While this is desirable for a number of reasons, it is not mandatory to enjoy the benefits of biamplifying." - SoundStage!

1) (lol) No active crossover is necesarily needed, but there are reasons to use one instead of a passive xover.

"[Active Crossovers] Good points: remarkable transient response, little (if any) phase shift, no complex impedance curves for the amplifier to play through, no Watts lost (all power goes straight to the speakers themselves), much more flexibility to adjust the speakers to your particular liking, the amplifier has much greater direct control of the speakers." - Some random site...

2) Actually, I was talking about a situation like this....
The woofer has about a 5dB peak at 500hz. So in addition to the regular high pass/low pass parts of the crossover, a circuit to attenuate ~350-700hz is built in.

The problem would be if you used an active crossover, the woofer plays its nasty peaky response just like it wants to, which means you'd have to use an eq or just screw the whole mess.

3) Well, it would be fun to try and all those extra parts would look cool :cool:

dorokusai

RS - Cool, had no idea. I know I have heard of active crossovers in car audio before. Sorry to group you in that mess.

I agree it sure would look cool, but I wouldn't want the mess of wires to make it work. I have yet to see a bunch of pictures of any high end setups, with an external crossover, sitting next to a $2000+ amplifier. That is just an example, but you know what I mean.

wlrandall

rs, if you want just a basic xover, look at a basic dbx model like the 234. Slightly better would be something from Ashly. For all out management, go with the dbx DriveRack PA.

Specs:

Features:

Stereo Feedback Elimination with 12 feedback notch filters

Dual 28-band Graphic EQ

Classic dbx¬ Compressor

120A Sub-harmonic Synthesizer

2x3, 2x4, 2x5, 2x6 Crossover Configurations

Stereo Multi-band Parametric EQ

Stereo Output Limiters

Alignment Delay

Pink Noise Generator

Auto-EQ with 28-Band RTA

JBL¬ Speaker and Crown Power Amp Tunings with Setup Wizard

25 User Programs / 25 Factory Programs

2 Channel XLR Input and 6 Channel XLR Output

Front panel RTA-M XLR input with
phantom power

24-Bit ADC/24-Bit DAC, >110 dB Dynamic Range

TypeIV¬ Conversion System

Full Graphic LCD Display


Technical Description

Analog Inputs

Number of Inputs: (2) Line inputs. (1) RTA Mic input

Connectors: (2) Female XLR line inputs. XLR RTA Mic input

Type: Electronically balanced/RF filtered

Impedance: >40k ohm

Max Input line level: +20dBu

CMRR: >45dB

RTA Mic Phantom Voltage: +15VDC

RTA Mic EIN: <-110dBu, 22Hz-22kHz, 150 ohm

Analog Outputs

Number of Outputs: 6

Connectors: Male XLR

Type: Electronically balanced, RF filtered

Impedance: 120ohms

Max Output Level: +20dBu

A/D Performance

Type: dbx Type IVœ conversion system

Dynamic Range line: 110dB A-weighted; 108 dB unweighted

Type IV dynamic range:
123 dB with transient material, unweighted, 22kHz BW
121 dB with transient material, unweighted, 22kHz BW
115 dB typical with program material, A-weighted, 22kHz BW

Sample Rate: 48kHz

D/A Performance

Dynamic Range: 112 dB A-weighted, 110dB unweighted

System Performance

Dynamic Range: 110dB A-weighted, >107 dB unweighted

THD + N: 0.002% typical at +4dBu, 1kHz, 0dB input gain

Frequency Response: 20Hz - 20kHz, +/- 0.5dB

Interchannel Crosstalk: >110dB min, 120dB typical

Crosstalk input to output: >+100dB

HBombToo

FWIW I have looked into this and found that the extra money required really would not benefit me and my settup which is the RTi lineup. I would imagine if you were really constrained by power limitations or perhaps a terrible room mode this could help but the expense is just too great IMHO.

I am a firm believer in simpler is better and the RTi's are 2-way crossovers simple.

HBomb

rs159

Well....it's not something I'm going to rush out and do tommorow. Maybe one day when I have some extra cash/luck into some old gear/something like that I'll try it.

Until then...