[Barry.B]

Hi All,

Deep breath, second post!

I'm sitting here listening to my standby system (Arcam CD9, Alpha 10 pre out to vertically bi-amped Lexicon NT 212's -read 3Bst's- powering LB1 classic's) as my Meridian G08's second DVD rom drive has decided to rattle on start up with several of my CD's again "and" my BP25 DA is on it's way to PMC to get a channel imbalance at low volumes plus the sticking mute/tape monitor switches sorted. Heavy sigh!!, but at least they are going to get sorted FOC.

I was shocked to hear the difference between the two systems in the detail, clarity and quality of sound.  I haven't listened to Arcam gear with the NT 212's until now as they should have been sold by now to pay for them (oops!), but the Bryston and Meridian system knocks the Arcam fronted set up for six.  It sounds thin and lacking of substance and muddled.  I can't wait to get the G08 and BP25 back in their rightful place.

To get to my point, whilst I was in my favourite store which is Phase 3 HiFi in Southampton UK (where I bought the BP25) arranging to get my gear returned, I got involved in a conversation about where I could improve my system bearing in mind the keeping my dear wife happy with size of speakers etc. 
The store manager suggested I consider adding supertweeters and a sub to the LB1's if space is at a premium.
He was suggesting something like Townsend supertweeters and a sub such as the PMC TLE1 or one of REL's product's, but he emphasised that in a pure 2 channel set up the sub needs to max at 35Hz or the result may be an overblown bottom end.  I know some of you guys favour M&K for the sub as the PMC is considered overpriced, but I'm not into AV/cinema yet.

I would really be interested in anyone's thoughts on this or if there is a better solution around.  I understand that the main benefits of the supertweeters is secondary/third harmonics helping the mid range.

Many thanks,

Barry.B


 

[Bob Reynolds]

He was suggesting something like Townsend supertweeters and a sub such as the PMC TLE1 or one of REL's product's, but he emphasised that in a pure 2 channel set up the sub needs to max at 35Hz or the result may be an overblown bottom end.  I know some of you guys favour M&K for the sub as the PMC is considered overpriced, but I'm not into AV/cinema yet.

Hi Barry,

I can't comment on super tweeters, but I have a couple of remarks about subs.

There seems to be two schools of thought about setting up a subwoofer. The bass reinforcement school says that you run the main speakers full range and let the subwoofer pick up where the main speakers leave off. This makes a lot of sense on the surface. As your dealer stated, you set the crossover relatively low in this scheme. The other school says that you high pass the main speakers and set the crossover higher somewhere near the 80Hz region.

In the bass reinforcement scheme you have multiple bass sources in the room which may interact in detrimental ways. Finding a good location for the sub can be more complicated with the interaction of the other bass sources. The woofer(s) in the main speaker are responsible for distortion as the frequency decreases and the SPL increases. So by running the speakers full range adding a sub has not helped the distortion characteristics of the speaker system. I think it's more likely that you'll end up with an overblown bass in this scheme, because you now have to select both an appropriate crossover point dependent on the characteristics of the main speakers and the volume level of the sub.

In the single bass source scheme finding a good location for the sub can be easier since there is less interaction with the main speakers. By high passing the main speakers at around 80Hz, the distortion of the speaker system should be reduced considerably. This also decreases the load on the amp(s) for the main speakers. Since the crossover point is independent of the main speakers, integrating the sub is now reduced to balancing the volume level of the sub with the main speakers.

I've applied the single bass source approach in two systems and I've been very pleased with the outcome.

-- Bob

[Barry.B]

Hi Bob,

Thanks for taking the time to respond to my post, it is much appreciated and made interesting reading.
I'll have to get my dealer to demo both ways of setting up a sub when the funds become available and go with what sounds best.

Regards,

Barry.B