vintage Sony speakers made under liscense in canada?

[system7]

Discussion of Vas is a bit irrelevant here IMO. It's always going to come out at about 30L or a cubic foot with a 8" bass. That's a decent size for deep bass and some excursion control in closed box.

Mounting the bass on the back of the panel is a typical BBC style lobing solution for a negative polarity tweeter crossing at about 2.8kHz. I'd build a removeable front baffle which you can experiment with.

 

[turk 182]

still doesn't help me decide on box size...

 

[system7]

It's just the choice of damping for closed box. You choose.

Bigger goes deeper, but the bass excursion or highest SPL gets worse.

http://www.diyaudio.com/forums/diyaudio-com-articles/158899-arpeggio-loudspeaker.html

An undersize box is a bit annoying IMO. With a driver Qts of 0.5, the critically damped box turns out to be the Vas in closed box.

 

[turk 182]

so how do i turn the pretty graph into physical dimensions (inches or centimeters)

i'm considering doubling the original box size and making an external (top) "mount" for the closed back mid and tweeter (a la steampunk or maybe just a nice piece of wood suitably finished)

 

[system7]

It's not rocket science. You keep the original volume if the bass is satisfactory.

Doubling the box size will take you into the overdamped region. You will encounter SPL limiting. The cone will flap.

I have already given you a rough idea of a two way filter for flat baffle:
http://www.diyaudio.com/forums/multi-way/245917-diy-kef-celestion-6.html#post3868470

The cabinet dimensions are a moveable feast, but (internal) Golden Ratio (1.618) and Root 2 (1.414) have something going for them. It's about the standing waves.

 

[turk 182]

if the box was allowed flex or a rubber membrane was used say enclosure back would this be congruent to an aperiodic tuning?

 

[turk 182]

rockets can blow up even on the launch pad....
where i come from using that in a sentence implies an intellectual slight....
without specifying a size how do you determine whether your over or underdamped?

 

[system7]

if the box was allowed flex or a rubber membrane was used say enclosure back would this be congruent to an aperiodic tuning?

I'd say closed box drivers will work best in closed box. Simple as.

Reflex drivers are Qts< 0.38. Aperiodic about 0.45, Closed box >0.5. Think I got that right...

Mate, you KNOW your current enclosure volume is OK! Why change it?

 

[turk 182]

if my math and measurements are correct the Qts 0.7
the enclosure volume is not ok i'm reasonably certain that better bass can be had but i don't want to go too big leaving me underdamped and boomy so it's a compromise variable that i'd like to narrow somewhat before feeding my tablesaw

 

[system7]

However big the box is, you are always going to tend to the boom box. That's how a Qts 0.7 driver is. The Qtc will always be bigger.

It's insoluble.

 

[planet10]

Sealed Sims based on the measured numbers. Note that this is without damping. Dapingwillknock the Q down somewhat (heavy damping can make the box appear to be as much as 20-30% larger)

There is no wrong answer, just that the larger the box you can live with, the flatter the bass response. An infinite size box would take the Q down to the measures 0.7 (unperceptively different from the bottom curve).

Note that a smaller box is easier to build such that box resonance issues are moot.

dave

 

[turk 182]

thanks
so i just need to translate 30-40 liters into inches or centimeters...

 

[planet10]

40 litres = 40,000 cm^3.

As an example, it is simple to create a set of dimensions for a golden ratio shaped box.

Take the cube root of 40k = 34.1 cm, given it is sealed and endvolume is uncritical choose 34 cm. Multiply by Golden ratio, = 1.618 to get 55 cm, divide by 1.618 to get 21 cm.

So a box with internal dimensions of 34x55x21 cm would do the job. Unlike a reflec box you don't even need to worry about space taken up by drivers or braces.

dave

 

[turk 182]

22 x 16 x 13 it will be...(78 liters) which about triples the current box volume they had originally.
i guess me first thought on doubling was ok

 

[turk 182]

well not sure if this is significant to identifying the driver source but the frame is similar (almost identical) to a marsland 6 inch so it could well be old Mcbride spec. made stuff.

wish greyhorse would reply; sure would like to communicate with his father for historical research.
still knee deep in the Clairtone story...

 

[turk 182]

so this project morphed into the combination of needing a new home for these "Sony" drivers and getting rid of an old console!
i cut the ends off the console giving me a much larger enclosure than i wanted but the flip up access doors allowed for opening and closing the mouth of a backloaded horn of sorts.

 

[turk 182]

after spending time on the synergy threads i think that what i originally thought was a mistake in manufacturing was intentional. the woofer cutout was smaller than the driver and acting as a low pass filter making voicing the mid and tweeter via low order x-over much easier/better.