[oris98]

Hi all,

I am biamping my Bryston 3Bst and 2BLP with the dual output in my Purist.  Now I am thinking of getting one or two music sub(s) into my system. Other than going to a active xo approach, are there any ways that I can do this without affecting sound qty ?

Thanks

[Marbles]

I am not aware of any other way to do it than an active XO.

I want to say I love the system you have and actively XOing those 9.0's to subs will be incredible.  The midrange will really clean up if the 9.0's don't have to play the lowest bass notes.

If I were you, I would contact John Casler about the NHT X2 active XO.

Full retail is $350 and he might cut you a deal.

It is a very nice Active XO and has some really cool features.

[oris98]

Hi Marble,
Did you tried active xoing your marble 9 before right ?  My question is do I need a 3 way active xo if I want to seperate the tweeter, woofer and a pair of subs for the effect that you suggesting ?  I can only find info on the web about NHT 1X but not 2x.  Where can I find info. for the 2x ?  Which Sub will match the marble 9s best in your opinion..

Many thanks.

[Marbles]

If you want to TRI-AMP, that is a different amp for the Tweeter, a different amp for the mid, and a different amp for your subs, then you need a 3 way active XO.

What I was talking about was a way to use the internal (passive) crossover of the 9.0, and crossing over to subs.

If you set the NHT X2 to cross at say 70 HZ, it sends the 70 HZ and above to the 9.0's amp, and the below 70 hz to the subs amp.

OK, we know it's not a brick wall, it's a 24 DB filter but for simplifications my example above is true.

You can get more info from John Casler on the NHT X2.  I have one and very much like it.

What this accomplishes is that your subs play the frequencies they are better at, the 9.0 no longer has to play frequencies it's not that good at, and it really cleans up the midrange.  

Dennis Murphy also has a nice passive crossover design for the 9.0.

www.murphyblaster.com

Tomorrow he will be getting my mini marble column 9.0 to do his magic on the XO.

Even crossing over to subs, you might want to talk to Dennis.
His nOrh 9.0 XO design is free and on his site if you want to DIY or have someone else build one for you.

[oris98]

Hi Marble,
I am using Dennis's design of XO for Marble 9s. They are very good.. you won't reget !  

Are you using a pair of stereo sub now ? What subs are you using ?  I only use it for 2 channel audio only.  

Thanks.

[Marbles]

I currently have two SVS Ultra subs running off a Crown K2 amp and eq'd with an ART 351 graphic .

Both subs are in the front right hand corner of my room, so currently they are not Stereo, but I could make them that way anytime I desired.

I only run them up to 70 HZ and cannot localize them.

I don't think they sound as good for music as either the Salk Ht3 speakers, or my RM40's, but they do a decent job for music and are GREAT for HT.

Removing the bottom octave or two from the 9.0's does make a big difference.....In any case they are very nice speakers...enjoy.

[oris98]

Hi Marble,

I just want to understand you correctly here is you suggest to maintain the Bryston 2B directly connected to the HF binding posts on the Dennis's design of XO of the Marble 9s (basiscally no change required).  That will take 1 set of line output from the Purist.  The second set of the line output of Purist will be connecting to the + and - line input of the NHT 2X and set it to cross at say 75 or 85hz.  Take the high pass line output + and - from the 2X and connect it to my Bryston 3BST -> the LF binding posts of Dennis's design XO.  The subout line output from the X2 will be connected to one or a pair of active subs or power amp to drive the subs )XO set to 75 or 85hz ?

Since the HF will not involve in the active crossing of the X2 circuit, will there be any tonal differeces or imbalance between HF and MF and LF ?  Any concerns there ?

Also, what would be the advantage to use stereo sub ?   If I go with the way you suggested, do I have to go with a pair of subs due to the fact that the LF has been filtered to and crossed to the sub amp ? or even with a single sub will be fine ?  I don't need very load base.. My room size is 17x17.  Please advise...
Many thanks.

[jqp]

Just a reminder and a little wishful thinking, IRD will one day come out with the PT-3, the 3-way active crossover.  Looks like a great design and a great price.

It will require up to 6 amps to make this all work ( I already have three monoblocks and 2 dual mono's with active biamplification). Or a combination of monoblocks and dual mono's...I am waiting for my next audio dream to come true!