Crossover question on 2 of my systems.

[Sleestack]

I have 2 HT systems in my home office. One includes Def. Tech. BP 70001 SCs, 3000C/L/R and BPVXs running off of a B&K 507 S2. The other is for my computer and includes a Polk RM6600 speaker system running off a Yamaha RX-V800.

The Polk manual states that I shouldn't run a separate LFE signal to the sub. Instead, it says to set the mains to Large, set the sub to Off and use the low pass dial on the sub itself to set the crossover. The way the speakers are set up, you run the speaker out through the sub and then wire the mains to the sub. Anyway, I just wanted to make sure that I wasn't losing anything by not running a separate LFE. It would seem to me that they way the speakers are wired, the low pass dial on the sub would effectively do the same thing. When I tried to wire the mains directly to the receiver and run an a separate LFE driectly to the sub., the receiver shut down before reaching even moderate volumes. When I wired the mains through the sub, ran a separate LFE and set the front speakers to Small and Subwoofer to Yes, I had no problems with shutdown but I did have problems getting a clean bass sound. Obviously, the fact that the speakers sound the best (for music) in the recommended setup, somewhat answers my question, but I just wanted to make sure I wasn't overlooking something.

With the Def. Techs, the manual says you can wire directly to the posts, set the fronts to Larg and the sub to Off and allow the speaker's circuitry to send the LFE to the sub. I'm assuming that means there is a fixed crossover (which I can't seem to find in the manual). It also says you can run a separate LFE, however, it says you should set the fronts to large anyway because the internal circuitry will send the LFE to the sub anyway. That is where I'm a bit confused. Is there any reason I should be sending a separate LFE signal if the speaker is going to send that signal to the built in powered subwoofer anyway. Is it essentially the same situation as my Polks?

I have read the very informative article regarding setting crossovers and speaker sizes, however, I'm a bit confused about applying it to my 2 systems. Thanks in advance.

 

[Sleestack]

Anyone have a thought on this?

 

[Sleestack]

Ok, so I found an answer that seems to indicate that I should be running the separate LFE, but, that I should disable the internal crossover. How do I do that without taking the speakers apart? If I don't want to do that (and potentially kill the 5 year warranty on my speakers) should I still run a separate LFE to the powered subs? If I do, won't that be sending 2 signals to the subs. Without knowing the internal crossover of the 70001SC, won't sending a full signal to the mains and a separate LF cause distortion in the low frequencies?

Assuming that I don't want to physically disable the internal corssover, should I not run a separate LFE and just allow the speaker circuitry to send thhe LFE to the subs?

I'm freaking confused.

 

[golfhack]

Sleestack,


Jeez!!! I got really confused after reading your posts. If you would tell us if your receiver has a sub-out output, if it has bass management; does it have pre-amp outputs for left and right mains?. Also, what kind of sub do you have; does it have high and low pass (line level)? With this information we will probably be able to give you your best setup to go with. In general, it is usually better IMO to separate the LFE channel from the other directed bass (from SMALL speakers). But most people don't have 2 subs in order to achieve this. That is of course unless you have bass management that allows for your sub to handle just LFE (subwoofer set to yes) and mains set to large (should only be done if mains can handle the low bass) then by all means this can be done with one sub. I for one, usually avoid speaker level outputs (from sub to mains) if I can. Hope this helps. If it doesn't then give us some of the information listed above. If not me, someone here will be able to assist you in giving you the best setup.

 

[Sleestack]

I run the Def. Techs off of a B&K 507 S2. The B&K allows me to separately route the LFE to the sub if I want, and yes, it does have a separate output for the sub. Each of the BP70001 SCs have a separate built in powered subwoofer and a separate line in for the sub (but not high/low pass). I'm assuming the speakers have a set internal crossover. The manual says you can just run speaker wires to the mains and the speaker circuitry will route the low frequencies to the powered sub, however it also says you can run a separate LFE. I'm just confused b/c I'm not sure how running a separate LFE would be any better than allowing the speaker to route the low frequencies via its set crossover. In fact, I'm concerned that if the receiver crossover is set different than the internal crossover and I run a separate LFE, I will get distorted bass signals.

 

[golfhack]

Do you have a separate (standalone) subwoofer for the dedicated LFE channel or are the only subs you have are the built-in subs of the BP's?

 

[Sleestack]

Do you have a separate (standalone) subwoofer for the dedicated LFE channel or are the only subs you have are the built-in subs of the BP's?

The Def. Techs. have each have a built in 1000w powered subwoofer. Despite the fact they are physically contained in the speakers, they are essentially 2 subwoofers. I could get a 3rd subwoofer, but in a 15' x18' home office, I think that would be overkill.

 

[golfhack]

In that case, you really can't have a DEDICATED LFE. In fact, the REDIRECTED bass will be mixed in with the LFE (both going to each mains). You're right, I wouldn't bother with another sub unless you REALLY want that separate LFE track. I would set your bass management to sub - no; send a full signal to both mains and let the internal crossover (the one in the speakers) handle the bass separation. Well...after a pause and reading your second to last post...I have decided that it is probably best to get advice from somebody more knowledgeable (sorry) If you go to Sound and Vision's forum, sign up (doesn't take long), and then post the question directly to COF (crazy old fart). He is extremely knowledgeable in audio. And he is always there (no kidding you will get a reply from him within 8 hours). He's usually there late night. If he can't help you I don't know anyone who could. Just post the thread as "COF help please". Again, sorry I couldn't help but I'm not very knowledsgeable when it comes to speakers with built-in subs. Good luck.

 

[Sleestack]

Thanks anyway. I'm glad you understand the source of my confusion. I was afraid nobody was answering b/c it was a stupid question... which it may be.

I have also sent an e-mail to Def. Tech.

 

[Sleestack]

Update:

I got an e-mail back from Def. Tech. They suggest setting the fronts to Large, Sub to Yes, running both speaker wire to the posts and an LFE to the Sub, and setting the B&K crossover to 80 to match the internal crossover of the Def. Techs. They say you can also set the fronts to small (which I will probably do).

 

[golfhack]

Sleestack,

Glad you got that all straightened out. Yeh, I would probably set the fronts to small as well, but try both ways and see which sounds better. Try playing something with emphasis on midrange...say, something with a female voice and check for the clarity.