Suggestion on a speaker.

[Alan0354]

Put the speaker face up and drive it at a reasonable volume.

Is there any issue hanging in mid air? I am sure the speaker will "walk" with the vibration sitting on the floor!! Also, that will shake the house and resonate with the sound.

I have heavy duty photography boom stand that can securely hang the 10lb speaker in mid air easily.

[Tone Meister]

Did you look at the link in my post #5?

[g1]

I don't get what the problem is hooking the speaker directly up to the variac set for 15VAC out?
Why is a transformer needed?

[Jazz P Bass]

I don't know what it is, but something tells me you should not run a speaker, at loud levels at least, without it being secured to a panel.

[Alan0354]

Did you look at the link in my post #5?

Yes, but that did not answer my question about hanging the speaker without cabinet in mid air where the speaker is facing almost horizontal.

[nashvillebill]

Did I miss something?

Why not break in the speaker the tried and true way...install it, plug in the guitar, and crank out some 3-chord rock'n'roll for a while. (Maybe some AC/DC in tribute to the announcement that Malcolm Young has suffered a stroke and can no longer play at his former level)

[Alan0354]

I cannot stand the loudness!!!

[Alan0354]

I just had the Marshall set up in the garage, I use a voltmeter and set the output voltage to 13Vrms into the speaker. It is not loud!!!! Without the cabinet, it is not that loud. I can see the cone moving!!!! I set it to about 65Hz to 70Hz, I just left the speaker on the concrete floor facing up.

Any objection to this? if not, I am going to run it like this for a few hours and see what happen.

Thanks

[Diablo]

Be careful with the AC voltage for break-in. The continuous cycle may burn your voice coil, depending on the voice coil material and watt rating. I've used a 5V filament transformer and let the speaker hum for a day. It doesn't need to be mounted in a cabinet, and as you found out it's not so loud and annoying.

[Alan0354]

It is a 75W 8ohm speaker, I am running 12V into it right now. W=(V^2)/R= 144/8=18W. That's about 1/4 power. I think I am very safe. I can see the cone moves about 1/8" or so. Very quiet, closed the garage door and I can hardly hear it unless standing close to the door.


I just check the speaker, it's been 1/2 hour, the magnet is not even warm, I can't even feel any difference in temperature. I think it's all good.

Should I raise to 15 Vrms?

[loudthud]

Try a lower frequency like 10Hz. Adjust the amplitude to get the cone moving about two times Xmax. It won't require a lot of power. This was suggested in the instructions for one of the Theil-Small measurement toys from Parts Express to break in a speaker before you measure the parameters.

[Alan0354]

Thanks, I'll try in the next round. I don't know whether I can get it that low frequency. I am running at 15V right now, I'm going to give it an hour or so first.

[Chuck H]

Should I raise to 15 Vrms?

Yup. Like I said in some earlier posts, cranking a 20W amp it took me six months to break in a 50W speaker with a hemp fortified cone. A year to break in a 60W speaker with a cone of some more normal composition. At 1/4 power you should be glad it's not too loud because it's gonna take a loooong time. I'd bump it to half the speakers rating. Maybe a little more.

No matter how far you take it I would expect additional break in time in the amp. The reason is simply that the speaker can't possibly be stressed in the same way running a sine wave as it would be dynamically popping chords with multiple frequencies. I have no science to back this up but my intrinsic sensibilities tell me it must be true. maybe you're idea of running a square wave isn't a bad one!?! I might stick to 1/3 power for that.

[Tone Meister]

I just had the Marshall set up in the garage, I use a voltmeter and set the output voltage to 13Vrms into the speaker. It is not loud!!!! Without the cabinet, it is not that loud. I can see the cone moving!!!! I set it to about 65Hz to 70Hz, I just left the speaker on the concrete floor facing up.

Any objection to this? if not, I am going to run it like this for a few hours and see what happen.

Thanks

See there, it doesn't hurt at all

[Alan0354]

I tried lowering to 34 Hz, the amp roll off and I had to crank it up. I stop that after a few minutes. I worry about burning the speaker because the speaker is spec. for guitar which is 80Hz or above with small voice coil and smaller magnet. At 30Hz or lower, the structure might not work as the magnet and coil is too small. Like if you try to run a 60Hz transformer down to 30Hz, core loss goes up, then impedance goes down and more current go through and heat up the transformer. That's the reason you need bigger core for 50Hz. Same applies to speakers.

So for now, I run 15V at 50Hz, at least it is closer and the cone move more. I'll go back to 60Hz and raise to 20W later after dinner. I don't want to wait for the rest of my life for it to break in!!!!