68kMLA Classic Interface

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Anyone have an SE speaker?
Posted by: DaveW on 2025-06-19 08:35:43
Sorry to necro a (recently) dead thread, but I'm sourcing a speaker for an SE/30 and am looking at the 45 ohm 57mm one ymk posted.
For those who have gone with something similar like David Cook, or the linked speaker, did you notice any issues having an unshielded speaker that close to the CRT?
I could always try and source a bucking magnet, but I'd have to measure first to see if I have the clearance for that.
Posted by: DaveW on 2025-06-20 20:32:52
So I ran a test on a Classic, with just a random unshielded PC speaker. Even at a distance greater than the SE/30 speaker sits, it noticeably distorts the image. I was really tempted on the speaker linked in this thread because it's 45 ohms and high sensitivity along with being able to buy all 9 that Arrow has for $2.43 (https://www.arrow.com/en/products/sp570445-3/db-unlimited), but I think I'll have to pass. There are some 57mm 45 ohm speakers available that are shielded though with lower sensitivity, I'll probably order one of those.
Posted by: ymk on 2025-06-20 22:59:15
You're placing the speaker near the deflection coil, not where it would normally be mounted.
Posted by: DaveW on 2025-06-20 23:59:35
You're placing the speaker near the deflection coil, not where it would normally be mounted.
Have you tried that speaker in an SE/30? I don't have anything comparable to test with unfortunately, and the speaker placement of the SE/30 makes it hard to temporarily install a random one in its place.

Measuring the distance between the tube and the speaker is similar to the distance between the tube and the top of the case, and if I place an unshielded speaker at the top and front which mirrors the bottom front location I still get significant deflection.
Posted by: Blinkz on 2025-06-30 09:41:46
I have a quick question on the topic of the speaker. Is the speaker polarity dependant from the speaker to the motherboard connector? If so which pin is for the + and which is for the -?
Posted by: shirsch on 2025-06-30 10:02:30
Speaker polarity is irrelevant to functionality. If it makes you feel better, connect the red wire to '+' on the speaker.
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