Restacking lams of speakerformers

Discussions and experiences with user adjustable gaps.
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Daniel
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Joined: Fri Jan 10, 2014 4:50 pm

Restacking lams of speakerformers

Post by Daniel »

Yeah, of course, just try it out, measure and listen. But I'm lazy and busy, so: has any of you ever experimented with restacking speakerformers?
With my AVCs I feel without experimenting with different stackings I wouldn't have gotten half of what they offer.
What does the math say in that case? With 800Hz and 7k55 crossover frequencies minimum inductance shouldn't be an issue?
dave slagle
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Re: Restacking lams of speakerformers

Post by dave slagle »

it simply comes down to inductance. if you have an excess then increasing the gap is worth a try.

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Daniel
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Re: Restacking lams of speakerformers

Post by Daniel »

Is it just about changing the lf rolloff due to a change of inductance or also trading that for a linearized BH curve?

I restacked the laminations in the tweeter attenuator to 3x3xrest of themx3x3. As it took me around 24h between listening, starting to restack and finishing and listening again the subjective results are questionable:
No change in tonality. Sharper stereo imaging. Voices moved up by 50-70cm.
Daniel
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Joined: Fri Jan 10, 2014 4:50 pm

Re: Restacking lams of speakerformers

Post by Daniel »

Changed stacking around a bit more and arrived at 2x2xrestx2x2. My narrow sweet spot got narrower than it was before with even less of a grey area.
Stero effect more defined, more details.
And that silver sound you get when changing from an AVC with copper to silver windings. That unique type of softness without losing details.
Daniel
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Re: Restacking lams of speakerformers

Post by Daniel »

SlagleformerVergleich2.png
SlagleformerVergleich2.png (6.32 KiB) Viewed 4383 times
Top: autofomer as delivered 3x3 stacking, in circuit, mid driver replaced with 16R resistor.
Bottom: stacked 1x3x3xrestx3x3x1

Level is the same, this is how the software displays multiple graphs. Driving it from a 50R output impedance generator probably makes this all monkey business.

Objectively there is no difference but how do you measure "the background choir on these two records are way more prominent in the blue graph and before I couldn't tell it was three singers"?
Last edited by Daniel on Mon Oct 03, 2022 7:18 pm, edited 1 time in total.
dave slagle
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Re: Restacking lams of speakerformers

Post by dave slagle »

It seems odd that the change in the gap would effect the level in the measurements and it really needs to be driven from a ~1Ω source for reasonable results.

My guess on the sonic results have to do with the lower inductance value of the 3X3 creating a high pass for information beyond what the speaker can reproduce thus decreasing doppler distortion. I do think that my earlier thoughts about the 3X3 and other stackings changing the sound has more to do with the overall change in L value rather than any linearization to it. When it comes to any form of alternate stacking you introduce a frequency / level dependent non-linearity so various configurations can modify behavior but none of them are as linear as a discrete gap.

dave
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Daniel
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Re: Restacking lams of speakerformers

Post by Daniel »

Level was the same. When I choose the "display multiple graphs" option they are spaced apart and there was one with a measurment glitch in between that I deleted. I'll hook up a chipamp and measure again.
Daniel
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Re: Restacking lams of speakerformers

Post by Daniel »

Yesterday I was at a friends place who has a similar setup as mine. We restacked his tweeter speakerformers and didn't notice any change. :lol:
dave slagle
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Re: Restacking lams of speakerformers

Post by dave slagle »

interesting.

My two questions on the situations:

Was the shunt resistor the same in both cases?

What was the nature of the crossover driving each autoformer?

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Daniel
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Re: Restacking lams of speakerformers

Post by Daniel »

My case: manganin film shunt resistor, 6dB serial crossover, 211 output tube through nano transformer

His case: manganin wire trimmer, dbx DSP crossover, safety cap before autoformer, 1875 chipamp

(His crossovers are still in the figuring things out phase, which is a lot easier with a DSP. The autoformer is in as a safety feature to not fry the Onken Tweeters. The trimmer makes it easier to set impedance to what ever we think is appropriate in the moment)
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