[James Tanner]

Thought I would start a new thread for Bryston Subwoofers.

 http://www.cepro.com/article/hands_on_bryston_mini_t_sub_exemplifies_max_engineering_prowess/

james

[James Tanner]

Hi Bob

Just wanted to say thanks for taking the time to review our Subwoofer.

James

James Tanner
Bryston Ltd.


"Thank you for the opportunity James.

It is such a well engineered product. It may be the most musical sub ever produced in the CE industry.

I had fun with it."

Best regards,
Bob
CE Pro

[drummermitchell]

It still bugs my ass that some say small drivers(say 8"x3) or whatever have just as much oomph as a 15"sub woofer.
I could be wrong but to me it's like using a shoe smith's hammer compared to a sledge hammer.
Twenty tiny shoe makers hammers will never make the impact a sledge hammer will do in one shot.
Look at a radio's woofer,even if you had six or 20 of them,no way can they slap you across the room  like a 15 or 18".
Or how about tossing 100 stones in the lake compared to a boulder,
which has more Slam and impact, the boulder of course.
Power also helps big time.
I'd love to be convinced that multiple woofers can reach down Lower and have just as much Slam as a 15 or 18"sub,it does not add up.
We are trying to moving huge amounts of air just like moving lots of resistance with the water with numerous small stones or a big boulder which has fantastic slam compared to a few hundred pebbles.
I'm hoping Bryston will do some 15's or 18's,jus cuz........aint bitchin as I'd like to buy a few Bryston subs but the woofer size just don't work for me or add up for slam and digging down to where no ear has feared to venture before  :thumb.

[James Tanner]

Hi Drummer

It has to do with surface area - 3 - 8 inch drivers will equal the surface area of a 15 inch driver - thats where the comparison comes from.

The advantage of stacked drivers like we are using on the T Series Subs is a smoothing out of what is called 'floor bounce'.  When you sit in a location in the room and the woofer is located in another location there is a big dip in the frequency response based on the distance you are from the woofer, the distance the woofer is from the floor and the wavelength involved.  With a single large woofer that dip will be fairly large at a specfic frequency.  With the stacked woofers like in the Model T each drivers are a different distance from the floor so there is a smoothing affect to the large dip.

But there is more to Subs than that as integrating them into the mains properly and having real headroom in the amplifier is critical to good designs as well.

james

[Grit]

Thanks James, that's very enlightening.

I had suspected that larger drivers resulted in lower frequencies; mostly I suppose because that's what one usually sees. There are lots of sub manufacturers that have a 10" that goes to 25 Hz and a 12" that goes to 20 Hz. I'm just making these numbers up for illustration, but the concept is alive and well.

The Model T sub uses 8" drivers, but goes all the way down to 18 Hz.

So, since it isn't the diameter of the driver that results in lower frequencies, what IS it?

- Garrett

PS - 105 Lbs!! I thought my sub was heavy at 75 lbs! And nearly 40" tall! That's spectacular.

[PMAT]

Floor bounce at subwoofer frequencies? Cmon man. The wavelengths are longer than the floor math. We are talking sub right?

[Grit]

Floor bounce at subwoofer frequencies? Cmon man. The wavelengths are longer than the floor math. We are talking sub right?

I suspect you'd still get reflections regardless of what point the wave is at, correct?

[klao]

Congrats on another good review, James.

According to Sound&Vision's magazine's bench test of the Mini-T Sub:  "The Mini T Sub’s close-miked response, normalized to the level at 80 Hz, indicates that the lower –3dB point is at 18 Hz and the –6dB point is at 16 Hz." Does it mean that the actual frequency response is actually lower than 25Hz, as published in your spec sheet?

Well, I tried playing some test tones with my Magnepan 20.7, and in my room I virtually couldn't hear the 25Hz tone at all.  So I guess, the Mini-T sub would be quite sufficient for my application (rather than the more expensive, bigger T Sub), correct?

Which of your "Red Rosewood" or "Boston Cherry" finish be closer to Maggie's "Dark Cherry" trim?  Thanks.

[James Tanner]

Congrats on another good review, James.

According to Sound&Vision's magazine's bench test of the Mini-T Sub:  "The Mini T Sub’s close-miked response, normalized to the level at 80 Hz, indicates that the lower –3dB point is at 18 Hz and the –6dB point is at 16 Hz." Does it mean that the actual frequency response is actually lower than 25Hz, as published in your spec sheet?

Well, I tried playing some test tones with my Magnepan 20.7, and in my room I virtually couldn't hear the 25Hz tone at all.  So I guess, the Mini-T sub would be quite sufficient for my application (rather than the more expensive, bigger T Sub), correct?

Which of your "Red Rosewood" or "Boston Cherry" finish be closer to Maggie's "Dark Cherry" trim?  Thanks.

HI Klao

We spec the Sub at 25 Hz anechoic as well as on our 100 ft tower but rooms have what is called 'room gain' which means as the frequency in the woofer goes down the room - based on its dimensions - will start to build volume at these very low frequencies. Most rooms seem to add level or a bump around 25Hz so in some rooms the measurements will actually appear to have a lower frequency response than the specifications would indicate.  Thats why room placement and room volume is so critical when placing subs.  In one room the Sub measures 30 Hz and in another 18Hz.

Which Sub you choose - Mini T or Model T  would be based on the maximum low output you would need to match the levels the Maggies are capable of without distortion.   Also if you want to smooth the response of the bass in your room using 2 Mini T Subs works better than 1 large Model T Sub.  I have the test graphs showing the advantage as you add 1-2 0r 3 subs to the same room and how it really reduces the standing wave issues in the room at low frequencies - I think I have posted them elsewhere on the forum.

james

[James Tanner]

Thanks James, that's very enlightening.

I had suspected that larger drivers resulted in lower frequencies; mostly I suppose because that's what one usually sees. There are lots of sub manufacturers that have a 10" that goes to 25 Hz and a 12" that goes to 20 Hz. I'm just making these numbers up for illustration, but the concept is alive and well.

The Model T sub uses 8" drivers, but goes all the way down to 18 Hz.

So, since it isn't the diameter of the driver that results in lower frequencies, what IS it?

- Garrett

PS - 105 Lbs!! I thought my sub was heavy at 75 lbs! And nearly 40" tall! That's spectacular.

Hi Garrett

Yes the 105 lbs is because we use a very substantial amplifier (with huge analog power supply) and well braced cabinet as well as woofers with very large motor assemblies.

james

[James Tanner]

Subwoofer Measurement:

Bryston measures/designs our subwoofers using a 100 foot Tower outdoors rather than other more typical methods available for measuring subwoofers.

We could bury the subwoofer in the ground and get a true 2-pi measurement or we could use the more widely utilized near-field technique. However, we don’t because we ‘have the ability’ to make a true 4-pi measurement. It is the “purest” and most direct and correct way. It is also VERY CONSISTANT, something that cannot be said for ground plane or near-field methods, unless an identical environment is used and the subwoofer position is not changed.

We also need this 4-pi ability to make the appropriate low frequency correction curves for our anechoic chamber and this must be done for EACH subwoofer model.

Finally, near-field computer techniques are fine for response at low volume levels, but impossible when trying to characterize subwoofer performance at high levels. It’s simply a matter of microphone overload levels when measuring near-field.

We also use the tower to confirm the low frequency response of our larger speakers like the Model T and Middle T.

[James Tanner]

Floor bounce at subwoofer frequencies? Cmon man. The wavelengths are longer than the floor math. We are talking sub right?

Hi PMAT

I will check with engineering on this as I may have mixed up the measurements I saw on the Model T which has 3 stacked woofers and goes much higher in frequency than our Subs do.

Will get back to you.

james

[James Tanner]

Here are some graphs showing what happens as you go from one Sub to 2 to 3.

Notice how the overall amplitude does not increase that much as you add Subs but the dip is greatly reduced.




james

[James Tanner]

Yes Sound and Vision Magazine did a full report on a Surround system which also included the Mini T Sub.  here is what they found:

The Mini T Sub’s close-miked response, normalized to the level at 80 Hz, indicates that the lower –3dB point is at 18 Hz and the –6dB point is at 16 Hz.

The upper –3dB point is at 125 Hz with the Crossover control set to maximum.—MJP

[James Tanner]

A couple of shots of the Mini T woofer:

[James Tanner]

Here are some of the graphs of the Bryston powered Subwoofer. 

It has excellent output down to 17 Hz with a max output of 108 dB in a 4pi environment.  This is a solid subwoofer.




The top line is the digital protection circuit limiting the output at very low levels if you exceed the capabilities of the Sub.  This prevents damage to the woofer.

james

[drummermitchell]

Interesting for sure.
Will have to see if Audio ark has a Bryston sub(s) so I can do a home audition and compare mine.
If two Bryston's do mine in,then I know where I can sell my 1812 instantly.
Before Bryston came out with subs I was using F-113's until the 1812 told a different story which was a major surprise to me.
Looking forward to the audition as always were looking out for the music .
James,what amp is in the subs,perhaps same as the 3Bsst or 4Bsst and is it Bryston,thx.

[James Tanner]

Interesting for sure.
Will have to see if Audio ark has a Bryston sub(s) so I can do a home audition and compare mine.
If two Bryston's do mine in,then I know where I can sell my 1812 instantly.
Before Bryston came out with subs I was using F-113's until the 1812 told a different story which was a major surprise to me.
Looking forward to the audition as always were looking out for the music .
James,what amp is in the subs,perhaps same as the 3Bsst or 4Bsst and is it Bryston,thx.

No it is a Class D 600 watt amp in both the Mini T and Model T sub with a huge linear transformer for lots of headroom.

[James Tanner]

Hi Folks,

There is now a link on our website to the Bryston Model A Sub - this Sub is two 10 inch drivers in a bi-pole configuration.

http://www.bryston.com/products/speakers/Model_A_Subwoofer.html

james

[mv038856]

Floor bounce at subwoofer frequencies? Cmon man. The wavelengths are longer than the floor math. We are talking sub right?

I am not that experienced with room acoustics, but the reflections of a subwoofer on the walls, the floor and the ceiling do matter.

Just think of a single bass array in a cubic room. There, four or more subs are placed on a wall so that they create a wave front eliminating two of the three room modes. The single bass array (SBA) uses the reflections of the side walls, the ceiling and the floor to acchieve this effect.

A Bryston sub is not a SBA, but just as the four or more point sources in a SBA add up to have an acoustic effect in a room, so do the two stacked drivers (=point sources) on a Bryston sub.

Cheers!

Markus