Can Avia show unknown crossover (1 Viewer)

[Dan Joy]

I have Sony STRDE-835. Can the Avia DVD show me what my receivers crossover is? And if yes, how?

My 25-31PCi is almost here and I am tring to get ready!

 

[Saurav]

You could try... set your mains to Large, turn off the subwoofer, play a bunch of test tones and record the output on an SPL meter. Plot them on a graph and see if you can tell the frequency at which the output is 3dB down from peak (you could use 1kHz or some similar high frequency tone as your reference for 'peak').

 

[Dan Joy]

Should I test it in small setting vs large. I will probably run front towers to small. Also, doesnt Avia test with LFE with mains in small or does lfe run that low?

Cant I use one of the settings with the dropping frequency?

 

[Steve_W]

Dan,

Are you originally from Chicago by any chance??

 

[Dan Joy]

Steve,

I am originally from the soth side. Resided in OK. for 7 years now.

 

[ling_w]

If you have a DMM or voltmeter, it would be much easier to use that tnen the SPL meter. With the SPL meter, you would also be measuring the freq resp variance of the speaker/sub.

If the system follows the THX crossover recommendation, then t get sub crossover freq, measure point where voltage drops to 50% of value relative to ref (any freq that does not have dropoff (30-50hz.)) For main crossover freq, measure where voltage drops to 70% of value relative to ref (1k.)

 

[Saurav]

Oops, you're right, small, not large.

ling_w makes a very good point, you don't want to measure the rolloff of the speakers. I don't know about the DMM - should he measure at the speaker outputs? That's usually better done with an 8 ohm load resistor (one that can take high wattage) connected across the speaker terminals. Connecting the DMM across the terminals would present a near-infinite load (be careful that it's set to measure voltage), which should be OK, but I'm not completely sure.

 

[Dan Joy]

Sounds like I will just calibrate it when it comes. Thanks for your suggestions, Sony has been no help and it is a DE receiver so I will just plug and play. I will set to small and hope all goes well. It was something that I actually got a SPL meter and disc let alone use a voltage meter( I would probably end up frying my house and others )

 

[ling_w]

It shouldn't matter where you connect it to, whether it is preamnp or amp out. It shouldn't make a difference with amp out and infinite load unless you have a really bad amp that shows significant drop in voltage with just an 8 ohm load. The amp out would be easier since you could parallel it up with your existing speakers (spade for speaker, banana plugs for DMM) and hear the freq you are measuring. You just have to make sure it is at a voltage range that could be measured precisely and not sounding too loud. The LFE would have to be measured via line out though, so no sound unless you use a RCA splitter.

A DMM is very useful, with some, you could capture min/max and see how much power (voltage) it is sending to the speakers. You could measure the voltage rails to the output stage and know the max voltage the amp could supply, and any measurements that goes above it means it is clipping; along with many other uses. It only comes down to how apt you are in wiring (parallel w/voltage measurement, series w/current measurement. If you get it wrong, expect some sparks and melted wires. I once hooked up the DMM to see my amp's turn on current drain, since it was tripping my 20A slow blow breakers once in a while. Upon turn-on, there was a big spark, the DMM lead wire melted or vaporized and its connector was fused to the AC plug. The DMM memory indicated an excess of 30A, its max current capability.)

 

[Chris PC]

Yeah, its difficult to measure the crossover via the speaker output in the room because of room gain and just basically the room itself. The room creates response which is different from what you would expect based on the crossover alone. Since you don't know exactly what the room is doing, then you will have trouble determining the crossover. You might get an idea, but if you can do the electrical way, then, thats a good idea.

 

[Dan Joy]

It would be a heck of alot easier if Sony would email me back or provide useful info in thier manuals

 

[Patrick Sun]

Current theories point to the Sony bass XO frequency to be in the neighborhood of 100Hz to 125Hz.

 

[Dan Joy]

Pat, How will that high Xover affect my mirage towers(spec35Hz-22KHz+/-3db I know they sometimes stretch this) with my 25-31PCi(using sub rca)?

 

[Steve_W]

Dan,

You aren't by chance the former trainer from Northern?? If you are..I'm Steve Wild..and I just ran into your brother Ed at a St. Patty's party...

 

[Dan Joy]

Go Huskies! Hey, Nice system by the way!

 

[Steve_W]

Yes the Huskies are almost back on the map...hopefully they can thump Wisconsin next year...

Small world!...I had not seen Ed since college until a couple weeks ago...he mentioned you had moved...are you still a trainer?? I lost $100 on that Oklahoma game dammit did you tape those ankles too tight??

 

[Dan Joy]

No, not really working as an athletic trainer too much. Pick up a couple of games on contract for area clinics. I do work as a RN nights and weekends so I can spend time with my kids(cant do the daycare thing!). My wife and I moved down here for her job and really enjoy it down hear(although I do miss Chicago). Gotta Go, Hope all is well!

Dan