Crossover setting?

[Quinn]

The 170 is +/-2dB down to 74Hz and -3db at 69hz. http://www.ascendacoustics.com/Main/Products/cb170specs.asp 80hz is the correct crossover point. You could try 100hz since the 170 is pretty darn flat into the 80s and see which crossover point sounds better to you.

[jbliz]

Yeah, I noticed that the -3db point for the 170's was 69hz, and that was what concerned me because an octave above that is approximately 140hz. I realize that THX recommends a crossover of 80hz, but that would require having speakers with a -3db point of 40hz, correct?

[Quinn]

I don't think it requires doubling Hz to go up an octave. Maybe someone more knowledgeable will tell us. But common sense says that a 10-30 hertz overlap won't leave any holes in the sound and should give a smooth transition between speakers and sub.

The only doubling rule of thumb I know of is that it takes twice the power for each gain of 3dB in volume.

Ron Stimpson the S in SVS has Ascend 170s in his HT. Call/e-mail him and ask where he crosses them over.

[Quinn]

Okay, I now have read more on octaves then I care too. You are correct that to go up an octave it is double the hertz. I too have seen the octave rule of thumb on crossover and can only conclude that audio guys are using the term octave incorrectly. They seem to use the term when meaning the next highest crossover setting from your speakers' lowest extension.

[Lou-the-dog]

I'm inclined to agree with Quinn. There's got to be an incorrect application somehow. Both the 170's and 340's bring to the table some pretty decent bass, I think, and a crossover setting at 140 would seem to lock out way too much of their ability. I know the sub would probably be able to reproduce this OK but I think the lowest crossover setting without creating a hole is certainly the best. I have mine set at 80 and the transition is flawless to my ears. Jbliz, if the octave rule in question was really true then the example of a 80hz crossover setting is only good for 40hz speakers would also be true. A 40hz speaker, in my opinion, is a full range speaker and a sub really shouldn't, for the most part, be needed at all except for maybe some home theater. Me thinks that there are too many home sound systems out there with the crossovers set at 80hz running speakers that are nowhere near full-range and getting good results. Feel free to correct me if what I am suggesting doesn't add up.

Randy

[jbliz]

Thanks for input Randy and Quinn.

Yeah, this is a very small issue, but I was just curious. I agree that the only speakers going to 40hz would be floorstanders, and that's just not in my budget. It's time to quit researching every little detail, and time to starting making the purchases.

I've obviously been spending too much time researching HT. I can't wait until my Ascend system is up and running. I'm sure I'll never think of octaves again.

Thanks,

John

[Lou-the-dog]

Actaully, thanks for putting this subject up for discussion. I've seen others discuss this octave thing before but I really never put the math to it to see what it all meant.

To me, doing the research before buying is fun and rewarding. I know what you mean tho, eventually one gets to the point that it's time to pull the trigger. I think you will be extremely pleased with the Ascends.

Randy

[Quinn]

John,
Spending all that time on research is how you and we found Ascends. I think you will be very pleased.

[Mag_Neato]

John,
I was playing around with crossover settings over the weekend. I have 170's - I found 80hz to be perfect. If I set it at 60hz, there was a big sonic hole. 100hz did not seem to make much difference. I would not go above 100hz as the sound from the sub can become directional at higher frequencies, in effect giving away the sub's location.

MAG

[jbliz]

Mag_Neato,

I agree, I wouldn't want to set a crossover above 100hz. That is indeed getting in the range of directional sound.

However, I play in a band and don't have the best hearing, so perhaps I wouldn't know the difference.

This is what got me concerned with the whole crossover setting in the first place. I applied the octave up from the -3 db point rule to the ascends and came up with 140hz. I was like, hold on here, that is just too high, something has to be wrong hear.

Anyway, glad to hear that it sounds good with an 80hz. I'm sure I'll probably bounce back and forth between 80hz and 100hz, depending on what I'm listening to and how much base I want.