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NOS betsyk's

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opa1

opa1

Member
Joined 2011
NOS Betsy k's Pioneer Build

I just recieved a pair of NOS hemp matrix Betsyk's. I have dims. for a small MLTL.[38.5x8.5x13.5 inside dims]
I just built the big MLTL's. I'd like something smaller. The pencil designs look good. No dims for betsyk though.

What would ya'll like to see built? Something new? Give me some ideas. Bibs are out for now.

Mark
 
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opa1

opa1

Member
Joined 2011
I've built the 48x21x14 mltl's. They work great. Just looking for another approach.
I'll narrow down the requirements some.
Powered by SEP tube amp. 10x10 room. Run at low volume. No sub support. Space taken up is important. Z height around 36" would be nice.

Ok, put 'em in a Karlson XK8.
Have you modeled a enclosure? Would stands be required?
 
F

fastbike1

Member
Joined 2009
Based on the measured T/S of my pair, they also model very well in 61 liters net BR tuned to 46.7 Hz. F3/F10 52/38. Flat response, 100dB w/ 5 watts Over xmax below 40Hz.

The box I modeled fits your requirements: 34.5"H x 17"w x 9"d (trying for wide baffle).

I've found they model well in BR anywhere from 61liters net to 99 liters. At 99 liters the port is just a 3" hole in 3/4" material.

All about the same output, just progressively lower F3/F10 as the box gets bigger. All flat FR


opa1 said:
I've built the 48x21x14 mltl's. They work great. Just looking for another approach.
I'll narrow down the requirements some.
Powered by SEP tube amp. 10x10 room. Run at low volume. No sub support. Space taken up is important. Z height around 36" would be nice.

Ok, put 'em in a Karlson XK8.
Have you modeled a enclosure? Would stands be required?
Click to expand...
 
GM

GM

Member
Joined 2003
Hmm, the pioneers of audio concluded that the optimum reflex net Vb was whatever raised the driver’s Fs 1.56x in a sealed cab and for high output impedance amps it should be tuned to Fs for best overall LF efficiency.

Based on published specs this equates to a ~2.03 ft^3/57.63 L net Vb tuned to ~50 Hz, so ideally these should be changed based on measured specs and source output impedance.

Using MJK’s L*0.349 driver offset = 36”:

L = 54.15”
CSA = 64.78”^2 + driver, bracing
zdriver = 18.9”
zport = 43.32”
rport = 3”
Lport = 0.75”

All dims i.d. [inside] and approximate and of course damp to 'taste'.

GM
 
GM

GM

Member
Joined 2003
Edit: ‘Pencil’ is a specific design routine, right? So we need a name for this particular MLTL design routine since any similarity to the Pencil is strictly coincidence AFAIK and could be quite ‘fat’ if the driver has a high Vas.

The ‘Pioneer’ series seems appropriate, but I’m ambivalent about such things, so any others?

GM
 
GM

GM

Member
Joined 2003
This small a net Vb for this driver in a tall cab causes too much HF ripple if the vent is located at the bottom, hence my positioning it at the bottom 5th of the cab.

Since the Pioneer’s alignment is fixed, its depth will be whatever 1.5x the driver’s protrusion into the cab is, then divide this into the effective CSA to get its internal width and if it’s not monolithic enough then you’ll have to decide on how big it can be and just call it 'Monolithic'.

GM
 
opa1

opa1

Member
Joined 2011
'no clue where the fraction came from.'

LOL, I'm not sure either. I tried the (1.618* 64.78)^0.5. That came out at 10.23wx6.33dx54.15h. I dont know if thats right either. It does come out to 2.03ft^3. If it is correct, It would be a cool build too. Not to mention alot less work. Have to change name back to Pioneer.
Mark
 
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GM

GM

Member
Joined 2003
Hmm, real close, 10.238 rounds up to 10.24. ;)

Don't know about you, but my tape measure is in fractions and I've reached the point where it's hard enough to see the 16ths marks :( that 1/8" is my accuracy limit these days, so 10.25" x 6.375" works for me.

GM
 
GM

GM

Member
Joined 2003
opa1 said:
It would be a cool build too.
Click to expand...

Yeah, I believe you'll like it due to having a bit of mid-bass bump while being well damped, so should be relatively immune to excessive overdrive as long as you don't use digital EQ to boost the low end.

I built a bunch of this type alignment way back when except with a ~40 Hz Fs, very wide BW 12" normally used 'full-range' in mono and early stereo consoles coupled to a plastic 1200 Hz, phenolic diaphragm, expo horn capped off 1st order with 2.2 uF. Great all round and party speaker for vinyl, 8 track tapes and AM/FM the rest of the time with both PP tube and early SS amps.

Wish I still had some components to see how they would fare against today's 'el cheapo' offerings.

GM
 
GM

GM

Member
Joined 2003
opa1 said:
Cool, Your going to get me to learn this stuff yet.:)

I'll figure up the materials. Lets cut wood.
Click to expand...

'Hope springs eternal' ;)

Wish I could do some speaker building, but my woodworking schedule/budget is currently limited to this whole property rehab that the housing market collapse has forced me to do.

Looking forward to your thoughts on the alignment and if there's a lot of tonal difference between these and the larger cabs.

GM
 
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