Babelfish M25, SissySIT - general building tips and tricks

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#2,321
Gents, where would you inquire in case of a sissysit lacking bite, being too soft with a gain lower than expected (both channels)?
With a friend, we measured my system before going bi-amp, and we drew the above conclusions.
Two months ago, bias and offset were spot-on, and I'm pretty sure sound was the same.
 
#2,322
pics, details

did you made any measurements regarding gain?
it's simple as inputing even crummiest 1KHz sine**, setting 100-200mV at input, and measuring what you get after buffer, after autoformer and at amp output

any DVM set to Vac is good enough for that measurement

**1KHz sine file on loop, headphone output of laptop
 
#2,325
Copied, and yes I have Cinemag 4LPC.
I'm sorry if you wrote it in many places, but I'm too far away from physics to be at ease with those conversions and interpretations (Vrms, Vpp, V/V, dB...).

So my Sissy behaves as expected regarding gain.

What I did learn is that it's probably struggling with the actual crossover (Liionidas open baffle, "simple" but not optimum croxssover).
Despite the low gain compared to the class D we tried, Sissy was beautiful with full range only, bi-amping with a miniDSP, waiting for Papa's crossover network.
But alone with the whole speaker, it's too soft in the medium, bass is deep but not properly controlled, etc...

Xover page 3
 
#2,326
with adequate speaker, even if SissySIT is (again, as declared) more THD Generator than HiFi amplifier - you'll hardly find anything snappier and potent, in actual power frame and considering projected facts - no NFB loop, moderate gain

adequate means - ohms are not so critical as critical is flattish impedance of speaker in frequency domain, usually called Impedance module

be it 15" RCA, 15" Tannoy or 4 way JBL 4343 or puny Dynaudio Contour 1.8 - SissySIT is more than good enough

make a test - you already tried driving just FR driver above; try driving just bass helper directly, without xover and compare how it sounds vs. your setup with "not optimum xover"

btw. my own solution for setup as yours was - FR connected without xover (directly) and just hefty choke in series with bass helper

xovers are easy to make as black holes
 
#2,327
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#2,329
G600 said:
What I did learn is that it's probably struggling with the actual crossover (Liionidas open baffle, "simple" but not optimum croxssover).
Despite the low gain compared to the class D we tried, Sissy was beautiful with full range only, bi-amping with a miniDSP, waiting for Papa's crossover network.
But alone with the whole speaker, it's too soft in the medium, bass is deep but not properly controlled, etc...

Xover page 3
Click to expand...
It's interesting to me that this open baffle speaker uses a series crossover. I use a series crossover with my own 2-ways and to me they sound far superior to the parallel crossover that is typically used with these speakers (Seas A26). The crossover point affects the way the midrange sounds- too close and the drivers are stepping on each other, loud but somewhat muddy, farther apart and the midrange level becomes lower but the vocals become less colored and more distinct. It's worth playing with if you have the parts.
 
#2,331
proper mounting arrangement shown in post #2 https://www.diyaudio.com/community/threads/the-singing-bush-tips-n-tricks.357497/post-6279704

Tokin case - dunno - Big Frog?

TO3 isn't, even if we can call case of 2SK180 as Big TO3

now, best solution for pair of (any) puck Tokins is https://www.conrad.de/de/p/kerafol-...mm-6-5-w-mk-l-x-b-100-mm-x-100-mm-189056.html

plastic bushings - for 5mm hole, inside for M4 screw - I bought mine years ago on Ebay, did send them with kits as long I had some ....... but relatively easy to find on-line

trickier part in finding them is to guess trade name (bushing, nippe,nipple,niple, hulse, ZM lost) of them, than they are actually scarce

I'm sending M4 and M5 eyelet wire connectors in kits, but these can be found everywhere, in nearest electric parts or automotive parts store

edit: said Keratherm is best solution, but I forgot to write - plain gray or pink silicone sheet (squishy, modern one) is more than good enough, due to sheer size of Tokin puck
 
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#2,336
The Tokin 2SK180 hole diameter is .205" ~5.207mm and flange thickness is .123" ~ 3.1242mm

The Tokin THF 51 Hole: .2" ~ 5.08mm and flange thickness is .102" ~ 2.591mm

This will work for #6 or #4 screws: https://www.mcmaster.com/products/n...ew-size~no-6/sleeve-od~0-187/screw-size~no-4/

This will work for 3mm screws: https://www.mcmaster.com/products/n...ers-6/screw-size~m3/?s=nylon-shoulder-washers

I can't find ones that will work for 4mm screws. But if you are mounting to an L or T bracket you can use a larger shoulder washer on the opposite side of the hole in the bracket to insulate the screw. See attached photos for example:

Rush
 

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#2,338
 
#2,340
New SissySIT build started, thank you ZM for an intact and complete set of boards and components.

First question from Post #1:

"- two tiny (isolated) wire bridges on right channel pcbs - mount it just for SissySIT "

Where do you install these tiny isolated wire bridges on right channel pcb, and what's the best method to do so? Are the tiny wire bridges included in the parts kit?

Many thanks in advance,

Jim
sissy.jpg
 
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