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Old 26th August 2010, 11:57 AM   #1
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Default Alu VS laminated ribbon

OK, here are my findings about differences among pure aluminum versus laminated ribbons. The ribbon was built for testing purposes, 1 meter tall, 20 mm wide, with a gap of about 0.5mm on each side, the magnets were N40 and the measurement distance exactly 50 cm.

The alu ribbon was 8 microns thick and the laminated ribbon had 12μ of mylar foil plus three alu traces of 8μ, about 6mm wide.
The weight of the 12μ thick mylar foil is less than that of the 8μ thick alu foil.

The impedance of the laminated ribbon was 3.3 oHms, and the alu ribbon had 3.4 oHms of resistance wire in front.

It seems both have roughly the same efficiency?

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Old 26th August 2010, 06:13 PM   #2
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Some more observations, pure ribbon has Fs below 5Hz, laminated has two: the fundamental one at about 9Hz and one at about 150hz, the latter is probably the result of my sloppy laminating technique. I have used extremely thin layer of spray glue.

On the plus side, the laminated ribbon is less sensitive to the slot anomaly between 5 and 6 kHz, has slightly more extended upper regions, but at the expense of somewhat more emphasized 15-22kHz region and less sensitivity below 1kHz (the baffle was 60cm wide, with ribbon at the side).

I have a Libra that shows marginally higher weight of the laminated ribbon but the difference is too small to be measurable.

Main advantage of the laminated ribbon over aluminum one is probably somewhat greater mechanical robustness and the corrugations can be shallower.

Any opinions?
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Old 26th August 2010, 06:25 PM   #3
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spl depends also on the source resistance , which should be taken into account , your levels/impedances do not match physical relationships .....

one impedance curve has a wiggle is it the laminated ribbon?

please try to estimate absolute splevel by comparing with a (flat response) driver with known efficiency/sensitivity at 2.83Volts input , on a baffle with same size/dimensions , and at the same distance! (1m distance would be better for comparison)

which glue did you used for lamination? did you measure weight of the al traces and finished lamination to determine how much mass was added?

would be nice to get the full picture without open questions ...

otherwise - nice work , well done!

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Old 26th August 2010, 07:09 PM   #4
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looks like the laminated has a resonance around 17kHz that should be filtered , younger ears will be annoyed by such a large peak ...

the minor peak around 4kHz should be equalized too , our ears are quite sensitive in this range ...

the Z-bump of the lam-ribbon comes most probably from the lessend stiffness across the width by weakening the structure through the mylar section between the traces ...

with the alpureribb version take care of hidden contact resistances , left/right levels may change by inproper mounting of the terminals ...

it is probably a good idea to clamp the alpureribb softly near the middle position with small foam pads on both sides , make it less supceptible to any air puffs etc ...

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Old 26th August 2010, 07:15 PM   #5
brunob is offline brunob  Germany
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Very interesting.

I have one question:
are the three laminated alu traces connected in series or in parallel?


Thanks,

Bruno
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Old 26th August 2010, 07:28 PM   #6
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by fivestring View Post
Some more observations, pure ribbon has Fs below 5Hz, laminated has two: the fundamental one at about 9Hz and one at about 150hz, the latter is probably the result of my sloppy laminating technique. I have used extremely thin layer of spray glue.

On the plus side, the laminated ribbon is less sensitive to the slot anomaly between 5 and 6 kHz, has slightly more extended upper regions, but at the expense of somewhat more emphasized 15-22kHz region and less sensitivity below 1kHz (the baffle was 60cm wide, with ribbon at the side).

I have a Libra that shows marginally higher weight of the laminated ribbon but the difference is too small to be measurable.

Main advantage of the laminated ribbon over aluminum one is probably somewhat greater mechanical robustness and the corrugations can be shallower.

Any opinions?
The pure alloy has better sound but will require a thin layer of mylar backing for good sonics, also better to use without corrugation ....

Could you measure with 2.83 volts @ 1or 2M , it would give us a better idea of your efficiency...

Quote:
Originally Posted by brunob View Post
Very interesting.

I have one question:
are the three laminated alu traces connected in series or in parallel?


Thanks,

Bruno
Series for it to be 3 ohms ....

Last edited by a.wayne; 26th August 2010 at 07:31 PM.
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Old 26th August 2010, 07:47 PM   #7
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The source resistance remains unknown to me, but my estimation is a few miliohms (Yamaha AX 396 has high damping factor=low output resistance).

About the impedance wiggle, read my additional observations.

At the moment I don`t have any drivers for comparison, but I was more interested in general tendencies of pure aluminum ribbon with the added resistance wire of the same impedance as the laminated one and to my knowledge on this forum nobody tried to measure this before.

I have used the "Tesa Sprühkleber" and as I said before the difference in weight was too small for my Libra to show up, my estimation for pure alu ribbon is 0.6 grams, laminate 0.8-0.9 grams.
The peak is at 22kHz not 17.

The laminated ribbon has three alu traces connected in series which gives 3.3oHms.

Unfortunately I don`t have voltmeter so everything is just relative, but I guess both lover curves would translate to somewhere between 83-85dB, no more. I am saying this because long time ago I have compared such ribbon to a dome tweeter of 90dB 1W/1m.

Almost forgot, someone from this forum reported four or eight times higher sensitivity of laminated ribbon VS pure aluminum one, whatever that means...
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Last edited by fivestring; 26th August 2010 at 07:58 PM.
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Old 27th August 2010, 05:08 PM   #8
brunob is offline brunob  Germany
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Quote:
Originally Posted by fivestring View Post
The laminated ribbon has three alu traces connected in series which gives 3.3oHms.
Another stupid question, if I may:
does the current flow in the same direction for all three traces?
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Old 27th August 2010, 05:14 PM   #9
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Yes!
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Old 28th August 2010, 08:36 AM   #10
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No!
ERROR!!!

Do humans make mistakes or only computers?
The middle trace was incorrectly wired, the new measurement shows much higher sensitivity, some 7-8dB higher than pure alu ribbon of roughly the same impedance!
Did no one ever tried to measure this? There must be clear benefits with such vastly improved sensitivity of the laminate, not only drawbacks?
I apologize for misleading you...

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Last edited by fivestring; 28th August 2010 at 08:39 AM.
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