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Old 21st June 2008, 07:16 PM   #441
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Quote:
Originally posted by gedlee


No pricing yet on anything that uses the 15" waveguide because I don't yet have the sourcing for that ironed out. Not too long though.

What would be the interest level in a full Summa size speaker?
You could sell a TON of kits if you did an Abbey with a low-cost woofer. Here's why:

The "real" Summa is a no-compromise design that mates a 15" waveguide & a 15" woofer. The achilles heel of the Summa is the woofer. There are only a handful of 15" woofers which can play into the midrange. The B&C 15TBX100 fits the bill, but it is E-X-P-E-N-S-I-V-E.

The Nathan 10 is a low cost alternative to the Summa; the kit costs less than 1/4 of what the Summa retails for. The Nathan ten has two drawbacks. It offers controlled directivity down to 1400hz, and the smaller woofer can't play as low as the Summa. Of course these are nitpicks; it's IS dramatically less expensive after all. You can save a few bucks by going with Eminence drivers, but why bother? The B&C woofers are superior, and the cost difference is less than 15%.

As I see it, the Abbey has the potential to be the most popular in the line. Here's why:
The Summa offers controlled directivity down to 920hz, while the the Abbey goes down to 1150hz. That's a *very* small difference, less than a quarte of an octave. To me, the most interesting aspect of the Abbey is the choice of woofer. The B&C 12TBX100 is an exceptionally expensive 12" woofer. Retailing for $295 here in the states, there are only a handful of woofers in it's class.

Your own studies have proven that the choice of drivers has little impact in the sound, despite popular belief. For instance, the substitution of TAD for B&C didn't improve the sound. Knowing that, you could easily substitute a dramatically less expensive woofer for the B&C.

For instance, the P-Audio SN12MB retails for half the cost.

I have a hunch that an Abbey which uses a low cost woofer would cost half the price of the Summa, while offering 80% of the performance.

Two other options are the Eminence Kappa 12 and the Deltalite II 12". Each retails for $130, vs $295 for the B&C.

Of course, there's no free lunch. The use of a less expensive woofer has drawbacks. However, I believe they would be all but inaudible in this application. The motor in the B&C 12TBX100 is a real work of art. B&C used a 100mm voice coil so that it could handle shocking amounts of power - two thousand watts! But that single design aspect carries drawbacks. A huge voice coil increases inductance, which then limits how high the woofer can play. B&C puts shorting rings in the motor to counter this.

Compared to the B&C, the Eminence and P-Audio woofers look liliputian. The P-Audio can only handle 600watts, due to it's dramatically smaller voice coil. But there's an upside! The P-Audio offers dramatically lower inductance, less than 1/4 of the B&C. This is easy to explain, there's simply less copper in the voice coil. Lower inductance allows the P-Audio to play a full octave higher than the B&C. Based on published specs, the P-Audio appears superior to the offerings from Eminence. The Kappa 12 has higher inductance, and the Deltalite 12 has similar performance to the P-Audio, but with a dramatic rise in the midrange.

Another upside to the use of a 12" woofer is a simplified crossover, which would further reduce the cost.

If the Abbey kit offers 80% of the Summa's performance for under $1998 a pair, that would be remarkable. And it seems like it's do-able IF the woofer was replaced.
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Old 21st June 2008, 07:43 PM   #442
MartinQ is offline MartinQ  Canada
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Thanks for your take on the situation Patrick. Its really great to have an outsiders opinion who is 'in the presence of' a Summa.


Quote:
Originally posted by Patrick Bateman
The Nathan ten has two drawbacks. It offers controlled directivity down to 1400hz ... The Summa offers controlled directivity down to 920hz, while the the Abbey goes down to 1150hz. That's a *very* small difference, less than a quarter of an octave.
So directivity to 1400Hz is a drawback, but 1150Hz isn't? Is that 250Hz difference (from 10" to 12") more significant than the 230Hz difference (from 12" to 15") ?



Quote:
Originally posted by Patrick Bateman
You can save a few bucks by going with Eminence drivers, but why bother? The B&C woofers are superior, and the cost difference is less than 15%.
Going from B&C drivers costing $300 per box ($163.03 + $131.96 CDN) to an Eminence set costing $175 per box ($119.99 + $54.99) is significant. I understand it is only one cost out of many, but when you are building 3-channels, all those little bits add up.

If what Earl is saying applies to this specific scenario (about different drivers having almost no sonic impact), then I'd be happy to save over $100 per box at this level. On top of that, my local supplier has a 7 year warranty on the Eminence, but only 1 year on the B&C.



Quote:
Originally posted by Patrick Bateman
Compared to the B&C, the Eminence and P-Audio woofers look liliputian. The P-Audio can only handle 600watts, due to it's dramatically smaller voice coil.
For an indoor home audio scenario I can't see needing (or wanting) more than 100-300 watt per channel for the mains (subwoofer excluded). I am interested in quality and efficiency, not high power handling.

For a different venue (dj, outdoors, club, bar) I could certainly understand higher power drivers and amps being involved.
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Old 21st June 2008, 08:00 PM   #443
gedlee is offline gedlee  United States
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All quite interesting.

But here are some points:

1) I never said that the drivers make NO difference only that competent drivers are all equivalent - that the differences aren't noteworthy. P-audio are not competent drivers. I have a closet full of them and not one of them met its "published specs", so much for the really cheap option.

2) You are missing the single biggest reason that I use the 12TBX100, it has a shorting ring. This I consider critical in a "competent" design because quite honestly I can't see why anyone would make a speaker without it. I'll have to look over the Eminence drivers to see if any of the woofers have shorting rings.

3) What I get the drivers for and what you are quoting are not the same thing and it factors into the equation.

4) I have already quoted the Abbeys at $1100 ($2200 / pair) is it really critical to get that last $101 out? I could do it, but I might question the value of that. The Eminence woofers might be a good idea since the ESP12 actually used an Eminence woofer. That change alone would not reduce the price $100 however.

But thanks for the options review. Very interesting.
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Old 21st June 2008, 08:16 PM   #444
Variac is offline Variac  United States
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I have to admit that despite what Earl says about it not mattering much , I find the B+C horn driver very appealing. It has a non-titanium diaphram and made by a company with a very good reputation.

I don't think that Patrick is saying that 600 watts will be used, but just emphasizing the quality of the driver. Also a speaker that can handle lots of power has less power compression, which IS relevant,

The Summa has a great reputation. The kits will sell better if they are "Summa clones", not some unknown.

I think that Patrick makes a good point about how the 12" version may require a less special woofer, to get into the midrange, than a 15", so may well be the best value speaker.

However , if the 15" goes low enough to make it possible to enjoy music without a subwoofer, then there is a large savings- even if the sub is a Costco! - less space taken also- better SAF.

So my opinion is that if you have any option, make it an alternative woofer,


EDIT: I was writing this as Earle Posted In answer to his question:
is it really critical to get that last $101 out?

My answer is NONONONONONONO!!!!!!

We want quality- that is the appeal of the Summas
I always want to love Eminence, but my experience with them hasn't been all positive, soundwise..
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Old 21st June 2008, 08:30 PM   #445
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Shorting rings lower distortion and inductance right? But a smaller voice coil also lowers inductance. Bastiani and Emerald Physics went this route; each uses a very inexpensive woofer paired to a high quality compression driver.

Admittedly, the cheaper woofer would have higher distortion.

When it comes to the compression driver, there is little excuse to use a $50 CD. First of all, we want very low inductance so that our response is extended. The Eminence is 1.6mh while the B&C is just 0.11mh.
In addition to lower inductance, the B&C uses a diaphragm with superior damping, while the Eminence uses titanium. If people don't like the sound of 1" titanium dome tweeters, they're going to hate the sound of an Eminence CD with a 3" diaphragm!

To make a long story short - it seems that the use of an inexpensive compression driver is a big compromise, but the use of a inexpensive woofer is less so.

Also, 99% of DIYers are complete cheapskates
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Old 21st June 2008, 08:45 PM   #446
MartinQ is offline MartinQ  Canada
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Quote:
Originally posted by Patrick Bateman
To make a long story short - it seems that the use of an inexpensive compression driver is a big compromise, but the use of a inexpensive woofer is less so.
This makes good sense. Again, I'm looking for the best compromise for a given situation, not the cheapest.


Quote:
Originally posted by Patrick Bateman
Also, 99% of DIYers are complete cheapskates
Totally agree .... not that this is entirely a BAD thing.
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Old 21st June 2008, 08:52 PM   #447
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Quote:
Originally posted by Variac
I don't think that Patrick is saying that 600 watts will be used, but just emphasizing the quality of the driver. Also a speaker that can handle lots of power has less power compression, which IS relevant


My main gripe with high power woofers is inductance. Hi-end prosound woofers use a 4" voice coil which drives up inductance dramatically. That limits your high frequency response. The addition of shorting rings offsets this, but increases cost. Even worse, the addition of shorting rings requires a larger motor, which FURTHER increases cost. Take a look at the motor on the 12tbx100 and the 15tbx100 - they're HUGE. And expensive.

Quote:
Originally posted by Variac EDIT: I was writing this as Earle Posted In answer to his question:
is it really critical to get that last $101 out?

My answer is NONONONONONONO!!!!!!

We want quality- that is the appeal of the Summas
I always want to love Eminence, but my experience with them hasn't been all positive, soundwise..
JBL made a speaker inspired by the Summa, but it's really REALLY cheap. Because the cabinets are crummy, the Summa KILLS it in the imaging department. I've taken my MP215s apart, and the drivers look like little toys. They are seriously the cheapest drivers you've ever seen in your life. But there's an upside to cheap drivers, and that's low inductance. If you look at the power handling of the JBL, it's just 250 watts, which is tragically low in the prosound arena. Yet I think JBL was *forced* to go that route - if they used a motor that was even a little larger, it would have been impossible to mate the 15in woofer to the 15in waveguide without resorting to shorting rings.

Check out the response graphs on the MP215 - you'll see that the cheap 15" they're using is just starting to run out of steam at 1khz. To my ears, the midrange response of the MP215s is pretty damn special, and I believe it has to do with the waveguide they're using, which was certainly inspired by Geddes. In other words, it's the waveguide not the drivers that's magic.

I'd really love to see tons of people with Summas, and it seems like a $999 speaker with 80% of the Summa's performance would be just the ticket.
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Old 21st June 2008, 08:53 PM   #448
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Quote:
Originally posted by Patrick Bateman
Shorting rings lower distortion and inductance right? But a smaller voice coil also lowers inductance.
Shorting rings can keep inductance low throughout the cone's stroke though. These drivers may similar or better inductances on paper, where inductance is measured with a small signal, but I ask you: how will they behave when the woofer is actually moving? I think that is where the money is well spent for the B&C driver.
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Old 21st June 2008, 08:54 PM   #449
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for some reason the URL for the mp215 isn't showing up properly, here it is a 2nd time

http://www.jblpro.com/mpro/PDF/MP215.pdf
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Old 21st June 2008, 08:59 PM   #450
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Quote:
Originally posted by augerpro


Shorting rings can keep inductance low throughout the cone's stroke though. These drivers may similar or better inductances on paper, where inductance is measured with a small signal, but I ask you: how will they behave when the woofer is actually moving? I think that is where the money is well spent for the B&C driver.
I'm really cheap, like a lot of DIYers. I didn't buy the Summa because I wanted "the ultimate" speaker, I bought the Summa because I realized that there was absolutely no way that my personal attempts at making a speaker would come close to what Dr Geddes is capable of.

So, absolutely, there are people out there who want "the best."

But there are also cheapskates like me who would be interested in a bit of cost cutting.

As far as the woofers moving, I can barely detect if the woofers are moving in the Summa. If they use 1mm of stroke I'd be surprised. They're sensitivity is so high I can't imagine I'm using more than a watt or three.
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