Using a Variac on speakers - a quiet idea

[rooster]

I have been using my Variac for some time now, to break in speakers and, where it has a good result, it makes so much noise I have grown to hate the process.

But this morning, I was thinking about it and I came up with a fix for this noise. No, not all of it but at least 70% of it, which is quite a lot. You could actually do this in your apartment without getting evicted I think.

OK, here's the deal. It takes two speakers to do this. If you have only one, no, not going to work. Take them out of your cab, and place one on the carpeted floor face up, and then put the other one face down on top of it - cone to cone. Now wire up your 1/4" plug with two wires, one positive, the other negative. Connect the positve wire of this plug to the positive tab of the speaker sitting on the floor. Then take the negative wire of the plug and attach it to the speaker sitting on top of this speaker - to the POSITIVE tab. Then take a jumper wire and connect the two speaker terminals that are not being used.

What this does, if you've done things correctly, is connect the two speakers together in series, but reverse polarity to each other. So one speaker is pushing out while the other is pushing in. When you couple the two speakers together, cone to cone, the bulk of the 60 cycle hum is cancelled out. If you doubt this, lift the top speaker off the bottom speaker and lay it next to it - a lovely 60 cycle hum if ever there was one.

To check your wiring work, you can wire things up and take a nine volt batt and attach its tips to the plug, tip and sleeve. You should see one speaker move out while the other moves in when you apply the batt.

The coolest part is I can run the speakers all nite and not disturb the household, wake up in the morning and check the improvement.

(Oh, and if you have a Variac and you have used it for this, you probably already have a cable with an AC plug on one end and a jack on the other, just plug the speakers into this like you always did, of course. I mention this for those who haven't used one for this purpose. Jim at Scumback listed some good voltage numbers for the process, BTW, you can probably find them around here somewhere.)

[Structo]

Cool idea as long as the cone excursion is not huge.

How many hours break in time do you figure?

[rooster]

Tom - Below is quoted from a post that Jim at Scumbacks Speakers made here a while ago. I copied it to HD and am reprinting it here. (I hope Jim doesn't mind. It is somewhere in the data base but I am sure I could not find it.) Jim's info has been very helpful. This said, he is not breaking in speakers the way I am suggesting on this post - and - not oddly enough, you will see that he doesn't run into the 32 ohm impedance situation I have over here by hooking two 16 ohms in series. So, his list is talking about a single speaker. FWIW, I am burning in two 16 ohm 30 watt Weber BDs at 12.5 volts. I am assuming I could go higher but, well, Jim probably arrived at his data from first hand experience - and I am not anxious to actually 'burn' these speakers up since I can't afford to do this. So I am looking at maybe 72 hours here.

I have decided that these ceramic Blue Dogs are just not broken in enough to be all that they can be. Even after many hours of use, and some previous Variac time (one speaker at a time) they are still pretty tight. Now that I can run them all nite, this job is suddenly very easy.



"Variac break in times are as follows:

Speaker
Imp Power Rating Break in Voltage How Long?
8___________ 65____________13.165____________2 to 3 hours - light break in
8___________ 30 ____________ 8.9
16___________65 ___________ 18.61 ____________8-12 hours - medium
16__________ 30 ___________ 12.64
8 __________ 100 ___________ 16.325 ____________20 to 25 - full break inl
16 __________100 ___________ 23.094

I usually limit the break in to 8 hours per session so the speaker doesn't overheat.

This formula is for the Scumbacks only.

If you want to do Celestion Reissues or Heritages, you're going to have to be very patient. When I mean very patient, I mean ridiculously patient.

I bought a few of the Heritage G12M 20 watt and G12H30's from a couple TGP members this year. They claimed to have put 120 gig hours on them, plus 40-50 hours of bedroom/TV volume and they were still too bright (hence why they were selling them so cheap).

When I got them I tested them. They were not as bright as a brand new Heritage M & H I owned before, but they were far from acceptable.

I put them on the variac for five days (40 hours). Still not enough. Put them back on the variac for another 2 days (16 hours)...still not there.

After 9 days on the variac they were finally broken in. Of course, this was on top of the 120 gig hours they'd already had.

I know a variac will break in a speaker roughly 2 to 2.5 times as fast as actual playing since it moves the cone constantly, so that 72 hours I had it on the variac was the equivalent of around 175 hours of actual gig volume plus the original 120.

When players informed me that it was around 250 - 300 hours of playing to get them broken in, they were right. The Celestion rep, Rick Skillman, told me the same thing back in 2005. I just didn't believe his estimate.

Turns out he was right. I don't have that kind of time available to wait for a speaker to break in anymore, personally. "




P.S. Yeah, as to cone excursion, when you think about it, if you use the same type speaker - since the one cone is moving the opposite direction of the other - there is no way they can touch. At least that's what I'm thinking. ??

[Structo]

Yes I remember Jim's post with that data.
I saved it as well.

What really amazed me was the time he said it took for Celestions to break in!

300 hours?!

Man, what do they use for doping the cones? Concrete?

I'll bet they do that because of complaints about cone cry.

But, that has to hurt business because I know that if I didn't like a speaker after a week or so, I would be dumping them as well.

300 hours, that is like two years of average playing time for most.

Do you know anything about the EVM 12L Classics?
These are the newer version of the classic 12L.

They sound ok but I would like a little less harshness with them.
Not sure how many hours I have on them but not that many.
Surely less than 50.

What do you listen for to determine when they are broken in?

[selloutrr]

As Tom pointed out the throw of the speaker is the variable as long as it has complete free movement and the speakers don't fall over you should be fine. If something does rub by the time you are finished burning in the speaker your speaker will be dead.

Make sure both speakers get plenty of air flow

Variac's do work but they are capable of so much more voltage then is needed it's safer to buy a dedicated transformer with a fixed voltage. If you have any questions on how to burn in speakers. YouTube has plenty of videos to explain it.

[Scumback Speakers]

rooster, no problem reposting my variac times for speakers. When running in series, though, you need to DOUBLE the times listed. I now have a 4x12 ISO box for breaking in speakers, but it's still a loud hum...I listen to it everyday, because over 1/2 my orders are now placed with the FBI service done to them.

If anyone has specific questions not covered here, email me. I'm busier than ever these days and I just don't have as much time to surf the forums anymore.

[rooster]

Jim - Cool, thanks for jumping in here to say it was OK to quote you - and for the info about the added time on the series hookup.

Frankly, I have had it with these speakers so I am going the distance whatever time it takes. Now that I can run them overnite, and it is quieter than the neighbor's hot tube pump, I don't mind at all.

Also, I am pretty sure, if Ohm's Law were to be applied, what voltage I am sending to the two speakers in series is split between the two 16 ohm loads. In other words, if I send 12.5 VAC to the series pair, one speaker is seeing only 6.25VAC. The fact that you have concluded that the job will take twice as long confirms this thought I think. EEs? I've been thinking about this today, so I will measure it in a minute now that I am focused on it and get back to you. But the job is so quiet now, I don't even mind doing it for 4 days instead of 2, or whatever it takes.

As to the EV12L, man that is one tough speaker. I know this may seem like a strange thought because it would seem a natural thing for a speaker to break in, over time. However, in regards to these types of speakers, the Altec 414A, the JBL K120, and the EV12L, I think they are broken in very quickly - like 1 hour of play time. I say this because of the flex ring at the edge of the cone. ?? Yeah, I guess they have to change over time but on the other hand, there is not much holding them back. The spider needs some time I suppose, too, but again, with such big mags they are designed to be more responsive than other speaker designs. Eh, just put the AC to them and they jump the same, new version or old, IMO.

So to finish my thought, Tom, and answer your question about 'how do I know when the EV12L is broken in?', I think with the EV12L, they are just very honest speakers from the gate. And here you see the Dumble guys falling over them and the TW guys running from them. What this says to me is that the EV12L can be tonally addressed better with the Dumble. With the TW amps, there is just not that much tone sculpting available. At least not the kind to make an EV12L sound like a vintage G12M! Eh, what can I say beyond this? Try the Variac thing on the EV12L - especially if you have two of them! - and run them in the manner I have described for a week maybe. Then get back here and tell me if it got smoother. What have you got to lose?

[Scumback Speakers]

Correct, the voltage is halved when you run it in series instead of parallel, so you have to double it. When Ted Weber & I worked all this out years ago we never explored the out of phase wiring and placing them cone to cone, but I do know he said the speaker had to have air for the cone to move. Obviously an airtight fit could restrict the cone's movement in this situation, but I doubt you have that with regular gaskets.

Other things to note.

You can accelerate the process by turning up the voltage more, but I'd advise no more than 20-25% over my posted guidelines so you don't overheat the voice coils/magnets with a multiple day run.

My rule of thumb is 8-9 hours on the variac, 1 hour to cool down, then another 8-9 hours. That's why a speaker takes almost a full day to break in.

The magnets can get quite warm, not scorching, but warm enough where you won't want to hold them in your hand for over 30 seconds if you don't have to. I have some first hand experience with that. LOL

It's a good idea to test the speaker BEFORE you variac it. Make sure it's working properly first, then do the break in according to the guidelines. Excessive heat/voltage will melt the voice coils. Ted & I worked out the voltage to 1/3rd the power of the speaker (per ohm/wattage rating) for Scumbacks & Weber speakers.

Other speakers could take a lot longer due to doping/suspension/cone stiffness/different cone treatments. In the case of the Celestions, as noted previously, it takes around 4-5 times LONGER than Scumback or Weber speakers due to their doping/cone/suspension parts. Probably why people love 20 year old Celestions since they're already broken in. My experiences with the Heritage line, and G12M/G12H30 RI models has been consistent with this as well.

[rbryerton]

This is some great info guys, thanks for the posts. The cone to cone/out of phase method that rooster posted sounds interesting to cancel out some of the noise.

Question: What would be the effect of using a 10 or 20 Hz tone, or say a 10kHz tone? This is outside of the sensitive area of the speakers reproduction and could possibly reduce the racket even more. But how effective would this be compared to 60Hz?

[rooster]

Jim - Yeah, more info, great. I did measure the voltage and it is evenly divided across the two speakers. And I have read what you added here, I won't ignore it. That said, I did up the voltage to 22VAC which puts 11VAC on each speaker. I will run this today, 8 hours, chill, and then start it up tonite again. This is moving along more quickly than it did with the original method plainly because I couldn't stand the rumble. Jim, I don't know how you can deal with it like that , day after day!

I was also thinking about a guy just plugging in a 4/12 cab and running it. Since its series/parallel, the same split voltage exists. Which means if you ran your cab for 72 hours and thought you got close, you better go another 72. That, or up the voltage because the series pair is splitting the voltage. Ha! I ran my 4/12 - loaded - for 16 hours over two days - and that was all I could take. It rattled the house. Now, realizing I could have upped the voltage, I am just dumb struck with thinking how LOUD that would be! NO WAY am I ever gonna be able to do that!

Again, thanks Jim for checking in here and sharing your data. BTW, I hope you check my idea out someday soon. Man, my head would be splitting right now if I had to deal with that hum all day long.

[Scumback Speakers]

Question: What would be the effect of using a 10 or 20 Hz tone, or say a 10kHz tone? This is outside of the sensitive area of the speakers reproduction and could possibly reduce the racket even more. But how effective would this be compared to 60Hz?

I didn't discuss that with Ted when we came up with all this. His feeling was that 60 cycles put enough "woof" into the speaker without subjecting it to a frequency WAY outside it's tonal range, which can sometimes damage a speaker.

He settled on the 60 cycle hum since it was just below most speakers low range, and that's another reason he felt more comfortable with the voltages specified, as it sent 1/3 the speaker(s) power handling to the speaker. I remember it being the thought that too low a frequency with more than 1/3rd power could hurt it if running for extended time periods.

I know I don't play for 9 hours straight anymore...constantly. When I was a teenager...sure...but my fingers ache with no rest. LOL

[selloutrr]

I'm not sure why you subject your selves to the noise day after day. why not build a room for it with an AC vent set the temp in the 68 degree range so the speaker never gets hot. set up a fan to move the air flow around the speaker and build a suspension system and mounting frame to decouple it from the floor and suspend it with rubber bundjee cords.

if it's your speaker go to a metal shop and have them weld you a couple rings the diameter of your speakers mouthing rim threaded with bolts so you can use wing nuts to quickly moutn and remove speakers. you could probably take them a 4x12 baffle and double mount the bolts so you could burn up to 8 speakers at a time.

the room wouldn't need to be very big use z strip to build the walls out like a recording studio. wire the on / off switch to the outside wall so you can turn it on and off before you open the door. add a window so you can look in. it would be a weekend project and probably under $500 total.
sure beats going crazy or having hearing loss from fatigue.

[rooster]

OK, I have added four styrofoam spacers between the two cones, to allow for air (not touching the cones), and used zip ties to secure the two speakers together. Since I upped the voltage it did seem like a good suggestion. Its pretty clear you can separate the two speakers up to at least an inch before the 'cancellation' effect is reduced, so nothing has changed.

Well, let me add, that as you increase the voltage, the hum is increased, too, so I do have more noise here. More than I had with 12.5 volts, yes, but then there is more cone movement. Even so, this is a walk in the park compared to running the same voltage into a cab with the speakers onboard - or even with the speakers sitting on the floor minus the cab.

Jim - a question for you? I have a pair of the Celestion EVH speakers and they have the 'new' type edge treatment on them - the almost invisible type doping. They seem way more movable than the earlier type with the very obvious dope. Have you had any experience with these cones and the new doping on them? They have to be easier to break in because they are sounding immediately better than any G12M RI I purchased ten years ago (Made in England). What is your take on this please?

Oh, selloutrr, that looks like a good idea. Jim, get on it, save yourself some 60 cycle wear and tear.

[Scumback Speakers]

rooster, ...whoops...edit...LOL (not EVM's Jim!)

I have those (they're basically Heritage models with EVH labels) in the Heritage G12M's I have. I had to put them on the variac for 9 days, right along with the G12H30 55hz Heritages I have.

New doping, but it was the same long break in time. This was almost two years ago that I got them. Previous owner had done 40-50 home use (probably mouse fart/TV levels) hours, plus 70-80 gig hours on them. He sold them to me because they still sounded bright.

Nine 12 hour days on the variac helped out a bunch. But that's the equivalent of about 250-300 total hours on the speakers at gig volume (when you add his hours plus the variac time). They're ok now, no longer ripping my ears off, but they haven't mellowed out enough for me to use them with anything except for comparisons.

Whenever I see EV, I immediately think Electro Voice, I didn't even read the EVH part. Sorry. (Told you I've been working too much lately!)

[Structo]

Jim or Rooster,
I haven't seen much information about the EVM 12L speakers as far as break in goes.

I have two of the newer EVM 12L Classic 200 watt speakers.
I've had them in the cab for over a year but I'm not sure of the amount of hours on them.

200W Power handling

• Frequency response: 80Hz – 7kHz (at -10 dB down)

• Heavy-duty cast frame reduces the low-frequency flex
inherent in stamped frame designs.

• Large 16lbs (7.3kg) magnet allows for higher efficiency,
better cooling and maximum output

• Manufactured in the USA