[James Tanner]

Hi James,

It been a while since I posted something, but I think we all want to get a sense of how these speakers compare to other speakers like the following:

1) IB2
2) JBL 1400 array
3) S8 signatures from Paradigm

I know it early in the developments, but it is nice to get a reference point from your vast experiences over the years ?

Ciao, Luigi

Hi Luigi

Yes it is a little early in the exercise but thinking about it I guess my best answer would be to give you my wish list for a speaker and hope the JT-1 comes close. The Active speaker concept was my start point so that eliminates a lot of other speakers out of the gate.

Bryston JT-1 Speaker Wish List

1.   Active speaker
2.   Lack of Dynamic Compression
3.   Excellent transient response
4.   Good total room power response
5.   Good even polar response well off axis – 30- 60 degrees
6.   Excellent frequency response – flat to 1 dB 20-20K
7.   Excellent phase response
8.   Excellent group delay response
9.   Sealed Box
10.   Active crossover and direct connection to each driver with separate amplifiers
11.   Low distortion

james

[SoundGame]

Bryston JT-1 Speaker Wish List

1.   Active speaker
2.   Lack of Dynamic Compression
3.   Excellent transient response
4.   Good total room power response
5.   Good even polar response well off axis – 30- 60 degrees
6.   Excellent frequency response – flat to 1 dB 20-20K
7.   Excellent phase response
8.   Excellent group delay response
9.   Sealed Box
10.   Active crossover and direct connection to each driver with separate amplifiers

Hi James - looking at your list, a couple key elements I thought that are missing from your list would be the following (though I'm sure you've considered them in one way or another in the design):

Very low distortion, including minimal cabinet vibrations
Reasonable efficiency - 86 db / 1 w / 1 m or better
Reasonable resistance / load - 4 to 8 ohms, without dipping below 3 ohms

[rofo]

Reasonable efficiency - 86 db / 1 w / 1 m or better

Reasonable SENSITIVITY - 86 db / 1 w / 1 m or better
efficiency and sensitivity are not the same thing.

[SoundGame]

Reasonable SENSITIVITY - 86 db / 1 w / 1 m or better
efficiency and sensitivity are not the same thing.

I stand corrected - definition of Efficiency vs. Sensitivity from Wikipedia below:

Loudspeaker efficiency is defined as the sound power output divided by the electrical power input. Most loudspeakers are actually very inefficient transducers; only about 1% of the electrical energy sent by an amplifier to a typical home loudspeaker is converted to acoustic energy. The remainder is converted to heat, mostly in the voice coil and magnet assembly. The main reason for this is the difficulty of achieving proper impedance matching between the acoustic impedance of the drive unit and that of the air into which it is radiating (at low frequencies improving this match is the main purpose of speaker enclosure designs). The efficiency of loudspeaker drivers varies with frequency as well. For instance, the output of a woofer driver decreases as the input frequency decreases because of the increasingly poor match between air and the driver.

Driver ratings based on the SPL for a given input are called sensitivity ratings and are notionally similar to efficiency. Sensitivity is usually defined as so many decibels at 1 W electrical input, measured at 1 meter (except for headphones), often at a single frequency. The voltage used is often 2.83 VRMS, which is 1 watt into an 8 Ω (nominal) speaker impedance (approximately true for many speaker systems). Measurements taken with this reference are quoted as dB with 2.83 V @ 1 m.

The sound pressure output is measured at (or mathematically scaled to be equivalent to a measurement taken at) one meter from the loudspeaker and on-axis (directly in front of it), under the condition that the loudspeaker is radiating into an infinitely large space and mounted on an infinite baffle. Clearly then, sensitivity does not correlate precisely with efficiency, as it also depends on the directivity of the driver being tested and the acoustic environment in front of the actual loudspeaker. For example, a cheerleader's horn produces more sound output in the direction it is pointed by concentrating sound waves from the cheerleader in one direction, thus "focusing" them. The horn also improves impedance matching between the voice and the air, which produces more acoustic power for a given speaker power. In some cases, improved impedance matching (via careful enclosure design) will allow the speaker to produce more acoustic power.

Typical home loudspeakers have sensitivities of about 85 to 95 dB for 1 W @ 1 m—an efficiency of 0.5–4%.
Sound reinforcement and public address loudspeakers have sensitivities of perhaps 95 to 102 dB for 1 W @ 1 m—an efficiency of 4–10%.
Rock concert, stadium PA, marine hailing, etc. speakers generally have higher sensitivities of 103 to 110 dB for 1 W @ 1 m—an efficiency of 10–20%.
A driver with a higher maximum power rating cannot necessarily be driven to louder levels than a lower-rated one, since sensitivity and power handling are largely independent properties. In the examples that follow, assume (for simplicity) that the drivers being compared have the same electrical impedance; are operated at the same frequency within both driver's respective pass bands; and that power compression and distortion are low. For the first example, a speaker 3 dB more sensitive than another will produce double the sound power (or be 3 dB louder) for the same power input; thus, a 100 W driver ("A") rated at 92 dB for 1 W @ 1 m sensitivity will put out twice as much acoustic power as a 200 W driver ("B") rated at 89 dB for 1 W @ 1 m when both are driven with 100 W of input power. In this particular example, when driven at 100 W, speaker A will produce the same SPL, or loudness, as speaker B would produce with 200 W input. Thus, a 3 dB increase in sensitivity of the speaker means that it will need half the amplifier power to achieve a given SPL. This translates into a smaller, less complex power amplifier—and often, to reduced overall system cost.

It is typically not possible to combine high efficiency (especially at low frequencies) with compact enclosure size and adequate low frequency response. One can, for the most part, choose only two of the three parameters when designing a speaker system. So, for example, if extended low-frequency performance and small box size are important, one must accept low efficiency.[34] This rule of thumb is sometimes called Hoffman's Iron Law (after J.A. Hoffman, the "H" in KLH).[35]

[JohnR]

Reasonable SENSITIVITY - 86 db / 1 w / 1 m or better
efficiency and sensitivity are not the same thing.

No they are not the same thing, but your first line makes no sense as the units are wrong.

[James Tanner]

Hi James - looking at your list, a couple key elements I thought that are missing from your list would be the following (though I'm sure you've considered them in one way or another in the design):

Very low distortion, including minimal cabinet vibrations
Reasonable efficiency - 86 db / 1 w / 1 m or better
Reasonable resistance / load - 4 to 8 ohms, without dipping below 3 ohms

Hi

With an Active system using our crossover and amps there is not really an issue of efficiency or load impedance because we will provide enough power to each driver directly from the Bryston amps.  Low distortion is critical - I will add that

james

[vegasdave]

I take it you will be using 28Bs?

[James Tanner]

I take it you will be using 28Bs?

Hi Dave

Probably not as each driver gets its own power and so far a 7B looks great on the woofers - although a 28B might be worth a listen. - everyone knows the 28B is the worlds best tweeter amp

james

[vegasdave]

Hi Dave

Probably not as each driver gets its own power and so far a 7B looks great on the woofers - although a 28B might be worth a listen. - everyone knows the 28B is the worlds best tweeter amp

james

Ok, James, sounds great either way!

[1oldguy]

Hi Dave

Probably not as each driver gets its own power and so far a 7B looks great on the woofers - although a 28B might be worth a listen. - everyone knows the 28B is the worlds best tweeter amp

James

You forgot about the Tubes in the 28B.

[Laundrew]

Hi Dave

Probably not as each driver gets its own power and so far a 7B looks great on the woofers - although a 28B might be worth a listen. - everyone knows the 28B is the worlds best tweeter amp

james

Yes, if they are smaller than 15 inches, they are only tweeters...

 

Be well...

[PRELUDE]

No they are not the same thing, but your first line makes no sense as the units are wrong.

Agree.

[PRELUDE]

Hi Luigi

Yes it is a little early in the exercise but thinking about it I guess my best answer would be to give you my wish list for a speaker and hope the JT-1 comes close. The Active speaker concept was my start point so that eliminates a lot of other speakers out of the gate.

Bryston JT-1 Speaker Wish List

1.   Active speaker
2.   Lack of Dynamic Compression
3.   Excellent transient response
4.   Good total room power response
5.   Good even polar response well off axis – 30- 60 degrees
6.   Excellent frequency response – flat to 1 dB 20-20K
7.   Excellent phase response
8.   Excellent group delay response
9.   Sealed Box
10.   Active crossover and direct connection to each driver with separate amplifiers
11.   Low distortion

james

12.  Must be three way
13.  Not expensive but smart
14.  Better use of power
15.  More control and and flexibility
16.  Higher damping factor(helps the driver to start and stop its motion more quickly)
Good luck James. Are you having fun playing with crossover points?

[rofo]

but your first line makes no sense as the units are wrong.

could you please explain? I believe SoundGame is presenting the units correctly

[audioligist]

i cannot explain anything but... (lol)

this is a very interesting thread which i have been following and learning a lot.

thx james and fellow audiocirclites.

[budt]

  Well, given the goals I would say CHEAP is definitely out of the question.I would like to see it with it's own dedicated active crossover which is equalized specifically for the speaker (and not just a one size fits all crossover). Build this with good drivers and they will come.

[James Tanner]

  Well, given the goals I would say CHEAP is definitely out of the question.I would like to see it with it's own dedicated active crossover which is equalized specifically for the speaker (and not just a one size fits all crossover). Build this with good drivers and they will come.

Hi budt - yes the dedicated crossover would have to be sold with the speaker - they could not be used without it. It is a symbiotic relationship

james

[SoundGame]

Hi James:

I'm thinking that this design could be set apart from your partnering company's house look and Brystonized, as it were if you took a little different direction with the front baffle that would likely be also a potential functional improvement.

Have you considered going with a:

1/2 thick solid aluminum front baffle with Bryston styling cues?
The baffle could be made in...black or silver.  A number of the high-end speaker seem to be adopting aluminum structural designs to increase structural rigidity and reduce cabinet vibrations.  I'm thinking this could improve the structure but also clearly link to the Bryston line of products. 

[James Tanner]

Some ideas?

[bummrush]

It is typically not possible to combine high efficiency (especially at low frequencies) with compact enclosure size and adequate low frequency response
 Above from previous post. Atlantic Technology speakers might beg to differ from what's written I would love to hear Jame,s opinion on those, I,ll throw on a teaser forhim by saying that Atlantic Technology probably isn't high end enough for you .Whatyou say James