Annoyingly vague crossover dials...

[lunchmoney]

Anyone else annoyed by how vague some crossover adjustment dials are?

My Emotiva preamp, for instance, has crossover adjustment dials that go from 50-250 with no other designations in between... yes, there are tick marks in between, but these sorts of adjustments are never perfectly linear...



Just about every subwoofer plate amp I've ever seen suffers from this as well.

How are you supposed to know where it's set? I know that ultimately you dial it in by ear, but it would be nice to know where it's actually set for a starting point.

Maybe I can figure out where it's set by using pink noise, a mic, and an RTA (DEQ2496)... Would this work? What would the RTA look like at the crossover point? How much lower in db would the x-over point be? (crossovers are 12db/octave)

Thanks

[Pete Schumacher]

Re: Annoyingly vague crossover dials...

Anyone else annoyed by how vague some crossover adjustment dials are?

My Emotiva preamp, for instance, has crossover adjustment dials that go from 50-250 with no other designations in between... yes, there are tick marks in between, but these sorts of adjustments are never perfectly linear...



Just about every subwoofer plate amp I've ever seen suffers from this as well.

How are you supposed to know where it's set? I know that ultimately you dial it in by ear, but it would be nice to know where it's actually set for a starting point.

Maybe I can figure out where it's set by using pink noise, a mic, and an RTA (DEQ2496)... Would this work? What would the RTA look like at the crossover point? How much lower in db would the x-over point be? (crossovers are 12db/octave)

Thanks

Depends on the type of slope the XO presents. If the output is LR4, then the output will be down 6dB at the XO point. If it uses Butterworth, then the output is down 3dB at the XO point.

[lunchmoney]

Re: Annoyingly vague crossover dials...

Hrrmph... I can't find anywhere what kind of slopes they are... not on the website, not in the manual... isn't 12db/octave enough of a designation?... or are you saying there are different types of 12db/octave?

[Deward Hastings]

Re: Annoyingly vague crossover dials...

Sometimes things are sold that are just not suited to the task they are sold for. A 12db/octave "subwoofer crossover" should probably be on that list (unless it's a 24dB low-pass and 12dB high-pass intended for "small" speakers).

Otherwise my inclination would be to use the "full range" outputs followed by a more suitable (4th order) crossover.

It does need to be acknowledged, though, that part of what they are telling you is that room modes and subwoofer position so dominate low frequency performance that in-room testing is the *only* way to get it (close to) right . . .

[Brent_S]

Re: Annoyingly vague crossover dials...

Instead of using the RTA in room, you could do a loop through test with RoomEQ Wizard to test at line level. The slope and xover point should be pretty obvious.

Sound card line out -> preamp in -> preamp out-> soundcard line in...run measurement.

-Brent

[DoubleTap]

Re: Annoyingly vague crossover dials...

There's this pretty cool new thing called a telephone ... I'm sure Emotiva has the info you want.

[evilskillit]

Re: Annoyingly vague crossover dials...

Brent's idea sounds pretty brilliant and should let you see exactly what the thing is doing.

"These things are never totally linear" Hrm, thats interesting. I hadn't considered that, it would be interesting to know if that is in fact true, or if they are linear and its our hearing that is not.

Just doing a bit of quick math you can figure that each dot is 20hz, so right in the middle between each dot is about 10hz. I know its not razor sharp exact but, assuming its accurate that should get you pretty close to where you want to be, then fine tune it by ear.

[Æ]

Re: Annoyingly vague crossover dials...

Hrrmph... I can't find anywhere what kind of slopes they are... not on the website, not in the manual... isn't 12db/octave enough of a designation?... or are you saying there are different types of 12db/octave?

Different types/shapes of filters. Butterworth, Bessel, Chebyshev, etc.
Here is an example:

http://en.wikipedia.org/wiki/File:Electronic_linear_filters.svg

[biff]

Re: Annoyingly vague crossover dials...

I might guess that they would have the same reason that the order of an electrical filter is , in some ways, irrelevant. Not knowing either the impedance or the rolloff of your satellites or sub I would think means that the final acoustic transfer function is itself a pretty big variable. OTOH, given what I have read about the accuracy of the internal XOs on some pieces, they may be doing themselves a favor by not marking things too precisely

[philiparcario]

Re: Annoyingly vague crossover dials...

lunchmoney I know this sounds silly, but you should test your hearing. Maybe you are down 3db in one ear. No joke my father-in-law was a bar owner the juke box was to his right side after 33 years of work he had better hearing in his left ear. i say this because you are going through a lot of gear and it does not sound right to you. phil

[lunchmoney]

Re: Annoyingly vague crossover dials...

lunchmoney I know this sounds silly, but you should test your hearing. Maybe you are down 3db in one ear. No joke my father-in-law was a bar owner the juke box was to his right side after 33 years of work he had better hearing in his left ear. i say this because you are going through a lot of gear and it does not sound right to you. phil

Ummm... ok... not really sure what you're referring to though.

The system sounds great, I was just wondering where exactly they were crossed (nit-picky nerd that I am).

[davepellegrene]

Re: Annoyingly vague crossover dials...

lunchmoney I know this sounds silly, but you should test your hearing. Maybe you are down 3db in one ear. No joke my father-in-law was a bar owner the juke box was to his right side after 33 years of work he had better hearing in his left ear. i say this because you are going through a lot of gear and it does not sound right to you. phil

I was thinking about that last night. I notice a lot of times imaging is not dead center it tends to be to the right a lot of times. Different speakers different amps and when its not centered its always to the right. Makes me wonder if its my hearing. I find my self turning my head to the right or leaning to the left a little.

[mzisserson]

Re: Annoyingly vague crossover dials...

Since you are in room-mode evil zone, I would Imagine it difficult to accurately use an RTA to measure the x-over. Unless you can use the RTA to monitor the INPUTTED signal and run a loop into the DEQ, then you can see your input and viola, a slope!

[lunchmoney]

Re: Annoyingly vague crossover dials...

Since you are in room-mode evil zone, I would Imagine it difficult to accurately use an RTA to measure the x-over. Unless you can use the RTA to monitor the INPUTTED signal and run a loop into the DEQ, then you can see your input and viola, a slope!

Great idea Mike!

I can definitely do that:

CD playing pink noise --> preamp with crossovers --> DEQ2496 (with RTA set to monitor input)

[AJ]

Re: Annoyingly vague crossover dials...

"These things are never totally linear" Hrm, thats interesting. I hadn't considered that, it would be interesting to know if that is in fact true, or if they are linear and its our hearing that is not.

If they used a standard active filter with linear pots, they will be linear depending on the quality of the pot. I'd bet your 20Hz per dot theory is plenty close enough.