Deleted thread.

[Scumback Speakers]

Deleted, update coming soon.

[greiswig]

Jim,

A couple of thoughts:

I've started doing breakin using pink noise through an amp, and it seems to take less time. It also may be more controllable: you can use a multimeter to measure volts and amps and calculate the RMS easily, then run the speaker at about 60-70% of capacity for awhile.

Those lamp timers you can get for your home when you're away on vacation? Those are handy! You can get ones that have 15-minute pins, so you can set it to go 60 minutes on, 15 off.

We also used to use auto light bulbs to protect speakers: the filament starts heating up as the capacity of the speaker is approached, creating resistance that protects the speaker. I'm not sure how to properly size them for use with a variac and a speaker, but perhaps that could be useful in cases where the variac drifts high?

Or...why not just get appropriately-sized transformers that won't drift? I suspect the drift might come from the contacts, so that would be eliminated in a set transformer. Not suitable for most folks here, bu for your FBI process, it might help keep things in line.

HTH, and best regards,

[selloutrr]

To help keep the voltage smooth consider a CVT Contstant voltage transformer as well.

[Alexo]

Have any of you guys thought about hooking your speakers up to stereo amps and just running music through them?

I don't think I'm alone in finding that speakers broken in at 60hz still need several hours of real-world playing time before the highs start to sound right, and it seems that something more full-range would accomplish this.

If I had a place to do break-ins, I would test this hypothesis, but that is just not happening what with the family and the cat and all..

...dang cat.

[tubeswell]

I find it faster to break them in with an amp that has tremolo on the verge of clipping FWIW

[Structo]

I think Jim uses an ISO cab and a variac but he could have changed.

I agree that full range music may work better or at least something with the guitar range in it.
Instead of one steady frequency (ie, 60Hz).

I have nothing to base this on, except my opinion.

[selloutrr]

60hz works find it's about loosening the speaker more then shaping it.

Full range music, or at least the frequency response of a guitar
Modern (85hz - 6.5Khz)
Classic (100hz-5khz)

will help form and break in capacitors.

The perception of highs is often your ears settling, tubes breaking in, or enviromental.

[Scumback Speakers]

I've had to change my break in method due to variac's having some fluctuation in current. I've been testing a new method, I'll find out if it's working/safe/etc this weekend.

Basically I had set a variac to a voltage, then hooked up four speakers in a 4x12 ISO cab. The problem I discovered was three fold...

1) The vibration from the cab would go through the floors to the variac, and it would shake it ever so slightly. That resulted in the dial either going up or down, increasing or decreasing the voltage. I have four variacs...one is right on spec 10v is 10v measured with a multimeter. The other three, I'm sorry to say (all import models) were not so good. When I had one set at 30v, it only put out 15v. Two others that were set at 10v, put out 15-16v. That led to a few low power 25/30w speakers getting fried. Needless to say, that pissed me off.

2) While I used to let the speakers run all night, sometimes the the magnets would be warm (normal), or cold (not normal), or hot (variac dancing on the dial issue from above), almost so you couldn't handle them. I've only had 7-8 failures in 3 years running them all night, but after shipping costs to rebuild, $25 rebuild fees, etc. that's about a $350 cost for those to be rebuilt. I had to minimize that, cooked/bubble voice coils don't last as long, and sound like A$$.

3) Got a suggestion from another amp builder that maybe what I should try is a digital timer. So I got one, and now I'm putting speakers on the variac two hours on, two hours off (to cool/minimize any variac drift). It's going to take just over a day to get the 12-18 hours in at that rate, but that should negate any overheating/cooking issues.

Right now I'm testing the digital timer out with some old G12M RI's I have to see how it's going. So far so good. The timer goes on/off for two hours on a cycle.

As for the variac dance from vibration, I'm going to have to isolate those with a shelf, put foam on it, then the variac on a piece of wood so the foam absorbs the vibration. That should kill the variac setting dance.

And I've had to calibrate each variac manually with a multimeter for the proper voltage and mark the dial for the proper settings.

Long story short is that I'm doing the break in process differently to minimize any potential damage to the speakers, so that's why I said an update was coming later, after I got it all worked out.

But since I couldn't delete this thread, I figured I'd better tell you what I was experimenting with.

More details/updates as I get it all dialed in.

The variac break in is effective at loosening up the suspension/cone/etc, but you have to take care in not overheating the voice coil or it will warp.

While the best way to break in a speaker is to just play it really loud, I know you can't just do that at will without a lot of space to do it in, which most of you don't have (or the ears to tolerate it!). So the variac break in method is the next best choice, as long as you monitor it and keep an eye on it.

[Structo]

while it may seem low tech Jim, couldn't you just slap a piece of gaffer tape on the variac dial once you confirm the voltage?

That should keep it from changing with any vibration.

[Scumback Speakers]

while it may seem low tech Jim, couldn't you just slap a piece of gaffer tape on the variac dial once you confirm the voltage?

That should keep it from changing with any vibration.

I could but since I have different settings for ohm/power handling, the dial setting changes every day or two.

My ultimate goal is to have four FBI boxes, each setup with a dedicated variac voltage setting, and all of them on the timer.

I just need to get the wall coverings done in the demo room, setup the workbench, and FBI boxes, and finalize the work room layout. It's going to be another month at this rate of weather/contractors/$$ to finish, etc.

[selloutrr]

Have you tried to decouple the speakers from the floor to help with the vibrations that are effecting the variac? You could go another step and float the variac as well. It would also help if the variac and speakers didn't share the same slab of concrete.

You might need to modify your variac to detent or use a dedicated transformer that is a set and forget. make sure it's kept cool and over spec'd for your needs along with a CVT and you should be set.
Running the Timer as a safety for the speakers to cool.

Have you considered using a fuse to blow if the temp / impedance gets over a safe level?

[Scumback Speakers]

I just road tested the setup yesterday, checked it this morning, and the 2 hours on, 2 hours off setup keeps the magnets cool, not hot. So that means the suspension/cone got exercised, but the voice coils didn't get overheated (which you could tell if the magnets were hot).

I even checked each of the speaker cones to make sure they were moving properly (opening that 4x12 ISO cab door is a sudden rush of volume!) while the variac was on.

My plan is to isolate the variacs from the cabs, and individually pad each cab as well.

Right now, it doesn't seem to have hurt to have the variacs on the carpet, as well as the cabs, but doing a foam padding/separate frame for each is my goal.

[selloutrr]

hocky pucks between to sheets of plywood make a cheep and effective dampener for heavy equipment.

Screw the pucks to the bottom sheet of plywood ever 8 - 12". To prevent the board from shifting tack an edge strip around the top sheet of plywood to frame it in and hold it in place.


Yoga dense Foam blocks work great for amps and cabinets.