Breaking in a speaker

[dude]

I just bought an 8" alnico speaker (new). I usually break my new speakers in by hooking up a small ac transformer to them and let the 60 cycle hum break in the speaker for 24/48 hours, Hum is annoying so the garage is a great place. Works great.

The PT secondary puts out 6.3vac but actually it's 7.3vac.  I've had no problem doing this to a 25 watt speaker and above but the little 8" 4 ohm speaker is 15 watts.  Hooked up the hum and shaking is a little louder than usual then my 30 watt speakers and I don't want to damage it, any way to lower the ac voltage, or 60 cycle hum?

I put a 2K7 5W R in series on the secondary to the speakers tip but the voltage is the same with or with out it, don't laugh I'm not a tech. Any help in getting this little break-in speaker PT to put less 60 cycle hum to the 15 watt speaker or is what I have OK?

Thanks,
al

[sluckey]

I put a 2K7 5W R in series on the secondary to the speakers tip but the voltage is the same with or with out it, don't laugh I'm not a tech. Any help in getting this little break-in speaker PT to put less 60 cycle hum to the 15 watt speaker or is what I have OK?

Can't be the same if the speaker is also connected in series with that 2.7K resistor. But that resistor is so big that the speaker will not receive enough juice to even begin to vibrate.

Does your PT have a center tap on that 6.3v winding? If so, use that. Or connect the PT to a variac and use the variac as a volume control.

[dude]

No CT on the 12.6vac tranny, two 120 primaries , secondary has two 6.3vac wires and a black common. I have each secondary hooked  up to two jacks to the tip and the common to each sleeve.

When I measure the acv on each sec. it's 7.3vac so the tranny is not 12.6 but 14.6vac.

I'd just like to get the voltage down a bit as it's only a 15 watt, 4 ohm speaker. Anyway to do it without a variac? 

I found this, pretty cool: http://www.unclespot.com/speakerbreakin.html

Says my 7.3acv is a little high. So, I'm running it at 20 minute intervals and checking the back for heat so far no heat after half hour. I have used this on several 30 watt, 8 ohm speakers and works great, just 24 hours and new speakers loose the harshness.

al

[Willabe]

No CT on the 12.6vac tranny, two 120 primaries , secondary has two 6.3vac wires and a black common.

The black secondary wire is the 12.6acv CT.

12.6acv/2=6.3acv. So, it's 6.3-0-6.3.

Secondary wind taped 1/2 way from start to finish of the wind= CT




               Brad       

[Willabe]

When I measure the acv on each sec. it's 7.3vac so the tranny is not 12.6 but 14.6vac.

The reading is high because there's no load on the secondary. It's a 12.6acv PT.


                 Brad   

[dude]

So if I put a load on the one secondary, like hook up a speaker, the acv will read closer to 6.3vac? Never knew that, so always check trannys with a load for true voltage....

 Sluckey: So the black wire with the two 6.3v secondary's is the CT and I've been using it all the time. If I hook up the two yellow wires only I'll get 12.6vac, right? And using one yellow with the blk sec gives 6.3vac.  I feel like a dumb A**  I should have known this stuff long a go, OH Well as Peter Green would say, live and learn.  Thanks for the lesson too, Willabe .

al

[Willabe]

I feel like a dumb A** 

Your not dumb. You can't know what you don't know.


              Brad   

[Willabe]

So if I put a load on the one secondary, like hook up a speaker, the acv will read closer to 6.3vac?

When I said a load, I meant something that will draw current. Tubes draw current and as they draw current they load (down) the power supply (PSU).

PT's are rated for a certain load. Bigger amps use more current than smaller amps.



                     Brad       

[dude]

So if I put a load on the one secondary, like hook up a speaker, the acv will read closer to 6.3vac?

When I said a load, I meant something that will draw current. Tubes draw current and as they draw current they load (down) the power supply (PSU).

PT's are rated for a certain load. Bigger amps use more current than smaller amps.



                     Brad   

That speaker humming is not a load, like you say, drawing no current.  The voltage across the hook-up vibrating speaker is lower but only by .2vac.

Just wondering if I put a diode (1007N) in series off the 6.3acv sec. would that change the 6.3ac  to dc?

al 

[Willabe]

Just wondering if I put a diode (1007N) in series off the 6.3acv sec. would that change the 6.3ac  to dc?

No, don't do that.

Speakers want to be fed acv.


                 Brad   

[dude]

Just wondering if I put a diode (1007N) in series off the 6.3acv sec. would that change the 6.3ac  to dc?

No, don't do that.

Speakers want to be fed acv.


                 Brad   

Yeah, I know that it's the 60 cycle hum on "ac current" that vibrates the speaker but I'm just wondering if it would convert ac  to dc with a diode.  If so will it be the same voltage but in dc, just learning here. Sometimes I want to tap dc off the filaments to run a small 12vdc fan (pc processor fan at low volts like 5 or 6) to cool things like a VVR.

[sluckey]

Just put it in that champ and break it in with your guitar. Or plug an Ipod in, turn the cab facing down and go to bed.

[Willabe]

Just wondering if I put a diode (1007N) in series off the 6.3acv sec. would that change the 6.3ac  to dc?

Yes.

A SS or tube rectifier will rectify acv to dcv.


                Brad   

[eleventeen]

You could also tune into http://onlinetonegenerator.com/ and dial in a very low freq signal, driving it via your amp for a few hours.


That's what my pal Scott Henderson does.

[jjasilli]

unclespot says to use 4.5VAC. (I agree.)  If you have a 6.3VAC, center-tapped filament transformer you can connect ONE outside leg & the CT to the speaker, for about 3VAC.  (Do not connect the other outside leg.)

[dude]

unclespot says to use 4.5VAC. (I agree.)  If you have a 6.3VAC, center-tapped filament transformer you can connect ONE outside leg & the CT to the speaker, for about 3VAC.  (Do not connect the other outside leg.)

Did the one leg, it was 7.3 volts, as I had no load. (I guess a little high for 15w  4ohm spk.) I put a 10 ohm 5 watt R in series across the one leg, got 3.6vac. That moved the speaker just right too.

al

[Fresh_Start]

Just put it in that champ and break it in with your guitar. Or plug an Ipod in, turn the cab facing down and go to bed.

I highly recommend "Electric Ladyland" for any speaker break in. Either that or a loop of "Wild Thing" from the Monterey Pop Festival...   


Chip

[jojokeo]

This is only one way to break in a speaker but:
If you really want to speed up the breaking in period, the easiest method is to connect the speaker to a filament transformer. Having said that, let's look at the precautions you need to take. Since you will be driving the speaker with a steady state signal, you don't want to drive it at its rated power or it will burn up the voice coil. 1/3 power rating is a safe figure to use. So, let's say you have a 50 watt speaker and it is 8 Ohm. 1/3 power is about 17 watts, and at 8 Ohm, that works out to be around 11.5 volts. Using a 12.6 volt transformer will put 20 watts into the speaker. I wouldn't have a problem with that in our products, but just to be safe, you might want to go with a 6.3 volt filament voltage, which will put about 5 watts into your speaker. Another option is to use a variac into the primary side of the 12.6 volt filament transformer and dial in the voltage you want on the secondary. That way, you can dial in the 11.5 volts we originally calculated at the 1/3 power level. I'd also suggest performing the operation in a garage or closet, because listening to the loud 60hz hum from the speaker will grate on your nerves very quickly. Also, if you leave the speaker out of the cabinet, the rear radiation of the speaker will cancel a lot of the front radiation and reduce the noise. You need to lay the speaker face up though, so the cone can move as much as possible since the whole idea of this operation is to loosen up the cone and spider. Laying the speaker face down would trap air between the cone and the surface of the table and restrict cone movement. You're going to be surprised how much the cone moves and how loud the speaker is, even at 1/3 power.
Here's the math for determining the correct voltage to use in case you have a different wattage and impedance rating than the example above:
1. Take the power rating of the speaker and divide it by 3.
2. Take that number and multiply it by the speaker's Ohm rating (4, 8, or 16)
3. Use your calculator to find the square root of that number.
4. The result is the voltage you need to use to drive the speaker at 1/3 its rated power.

[jojokeo]

Here's more info from Jim of Scumback speakers:

The 6v filament will take forever. Here’s how to do it with a variac

Speaker break in with variac voltage settings. Wire your speakers in parallel to do more than one, but use these settings as if there were only a single (Two 16 ohm speakers use the 16 ohm setting). If wiring in series, double the break in time.

Variac break in times are cumulative, meaning total hours on the variac. You'll want to do them in two hour shifts (MAX), then two hours off to cool, then on again for two more hours. That means it will take two full days to do speaker break in:

Speaker Ohm Imp      Speaker Power Rating    Break in Voltage        How Long?
8                                   30                                  9                          Light Break in= 2 to 3 hours 
8                                   65                                 18                         Medium Break in = 8-10 hours
16                                 30                                 9                           Full Break in = 16 hours
16                                 65                                 18

Dude: Any method you choose I suggest you adhere to the two hours on and two hours off recommendation.

[dude]

Hey jojokeo,

I understand. I got a 6.3 filament PT, one leg with a 10 ohm resister in series, puts out 3.3 volts. Hums just right for 15 watt speaker.
I ran it for half hour and check the squeaker cone, not warm. So, I ran it two on two off for a day.

Sounds nice now but it's bright. I have an Alnico 10" (8ohm) that I run in parallel with the Weber 8" Alnico (4 ohms). I measured 3 ohms together. But I pulled the small OT in the Champ and put in a single ended old paper OT I had laying around, much bigger. Sounds fantastic with the stock 8 and the 10 together. 

[jojokeo]

Using the first example I posted 6.3v was actually "supposedly" perfect for that speaker all along? But it's better to error on the side of caution, no sense in throwing money away. You end results are all that matters in the end.

Could you try to describe your speaker how it changed from before to after? Was it worth it after all?

[pinkphiloyd]

I second what a few others have said.  I bought a little 2 foot long, 1/8" stereo to 1/4" mono adapter cable from Radio Shack, about 4 bucks I believe.  I put the speaker in an amp, plug phone into amp, and rock out while I do whatever I need to do around the house.  People always say recorded music sounds horrible through a guitar amp and guitar speakers, but I've found if I'm using an amp with a decent amount of headroom and a decent tone stack, I can get it to sound pretty good.  I mean, it's not hi-fi or anything, but it's certainly fine for jamming while you clean out the garage or replace your spark plugs or whatever.

[jojokeo]

I second what a few others have said.  I bought a little 2 foot long, 1/8" stereo to 1/4" mono adapter cable from Radio Shack, about 4 bucks I believe.  I put the speaker in an amp, plug phone into amp, and rock out while I do whatever I need to do around the house.  People always say recorded music sounds horrible through a guitar amp and guitar speakers, but I've found if I'm using an amp with a decent amount of headroom and a decent tone stack, I can get it to sound pretty good.  I mean, it's not hi-fi or anything, but it's certainly fine for jamming while you clean out the garage or replace your spark plugs or whatever.

+1 not a big deal for me