Help with bad tweeters

[rockblock]

Hi Folks, I'm quite new to this, so any help would be greatly appreciated.

I just got a pair of used Sony tower speakers SS-AV55 (130W) that each have 2 woofers (6" each)+ 1" dome tweeter.

The problem is that I think tweeters are busted, as only the woofers can be heard. I took out the tweeters and checked them each individually...they produce barely any sound...with my ear against them and slowly turning up the volume, I can barely hear anything...upon taking the tweeter out, through the hole I can see that internally, all 3 drivers feed into some sort of circuit board with capacitors & coils (I guess it's the crossover board). On the other side of the board are the 2 speaker connections.

The tweeter has no specs on them, just some numbers stamped on the magnet. The only specs that I see are on the back of the cabinets:

SONY MODEL SS-AV55
SPEAKER SYSTEM
RATED IMPEDANCE: 8 ohms
MAX INPUT POWER: 130W (non-clipped)

So, does this mean that each of the 3 drivers drivers has an impedance of 8 ohms? Same for power: does the 130W mean that each driver can handle 130W, or is that the combined power? How do I know what wattage I should be looking at for when choosing a suitable tweeter (I've seen them go from 25W->100W).

Also, what does "non-clipped" mean?

It's interesting how both tweeters react the same way...

Any help would be greatly appreciated.

 

[Swerd]

It seems like have already done some basic trouble shooting. When you opened the speakers, did you see any connections that looked like they had become separated, such as a failed solder or crimp joint?

I'm a little surprised that the tweeters can produce any sound at all. You said they barely produce sound. Usually when tweeters get fried from being over driven, perhaps by a clipped signal, the can't make any sound at all.

It is unlikely that components on the crossover boards are causing this problem. These components rarely fail, and if they do, the result would be no signal at all going to the tweeters.

It seems like you may have to replace the tweeters. Contact Sony customer service (good luck with that ) for more information. I guess you may have to decide if it is worth repairing these speakers, based on how much you payed for them, and how much Sony wants to replace both tweeters. You will be better off that way than if you search for a suitable drop-in replacement.

A "clipped signal" is a description of the waveform created by an over-driven amplifier. A good waveform is sine wave shaped like the green trace in this figure. A clipped waveform, see the red trace where the tops of the wave are clipped off, is produced when an amp is driven too hard. Amps over-driven into clipping are known to fry tweeters.

Those other specs, 130 watts max input power and 8 ohms impedance, refer to the speaker as a whole, but is obviously related to the individual components. Exposing the speakers to more that 130 watts for some unspecified length of time may cause them to fail. I can't say for sure without hearing those speakers, but it is likely that playing them at full volume with a 130 watt amp would be too loud to listen to for long. It is more likely that they were damaged by turning up a weaker amp up so high that it clipped.

Good luck with your repairs.

 

[rockblock]

I'm a little surprised that the tweeters can produce any sound at all. You said they barely produce sound. Usually when tweeters get fried from being over driven, perhaps by a clipped signal, the can't make any sound at all.

It is unlikely that components on the crossover boards are causing this problem. These components rarely fail, and if they do, the result would be no signal at all going to the tweeters.

It seems like you may have to replace the tweeters. Contact Sony customer service (good luck with that ) for more information. I guess you may have to decide if it is worth repairing these speakers, based on how much you payed for them, and how much Sony wants to replace both tweeters. You will be better off that way than if you search for a suitable drop-in replacement.

Those other specs, 130 watts max input power and 8 ohms impedance, refer to the speaker as a whole, but is obviously related to the individual components. Exposing the speakers to more that 130 watts for some unspecified length of time may cause them to fail. I can't say for sure without hearing those speakers, but it is likely that playing them at full volume with a 130 watt amp would be too loud to listen to for long. It is more likely that they were damaged by turning up a weaker amp up so high that it clipped.

Good luck with your repairs.

Thx for your prompt response & explanation. Yes, it seems weired that the tweeters produce a barely noticeable output, while the woofers pump hard...I was definitely thinking about changing the tweeter drivers, and, while I've found matching impedance (I assume I'd be looking for 8 ohms) and dimensions, I'm a little puzzled by the wattage, as I found tweeters ranging from 25W->100W...given the 130W overall speaker specs, what power should I be looking for?

Once again, thx for your time.

 

[TLS Guy]

Thx for your prompt response & explanation. Yes, it seems weired that the tweeters produce a barely noticeable output, while the woofers pump hard...I was definitely thinking about changing the tweeter drivers, and, while I've found matching impedance (I assume I'd be looking for 8 ohms) and dimensions, I'm a little puzzled by the wattage, as I found tweeters ranging from 25W->100W...given the 130W overall speaker specs, what power should I be looking for?

Once again, thx for your time.

Actually in cheaper speakers like that, the crossovers quite often fail as cheap electrolytic caps are used frequently. These pretty much all change in value over time and cause the problem you are talking about and more.

Replacing a tweeter with another type is seldom satisfactory. First of all the replacement tweeter has to have the same sensitivity, if it is higher it will play too loud and if lower too soft. Also the tweeter has to be able to handle the lower frequencies that the crossover lets through. The DC resistance and inductance of the speakers has to be the same. The last issue is that the low frequency roll off of the tweeters has to be the same. Unless we know the precise details of the tweeters we have to match we can't help.

There are two possibilities for the problem you are describing. The most likely is that there is an electrolytic capacitor or capacitors in series with the voice coil, that now have a much lower value than they used to.

The other possibility is that the tweeters were over driven and that the voice coils over heated, melted the insulation between the turns and now a lot of turns are shorting together.

You can sort this out, by removing the tweeters and measuring the DC resistance of the tweeters with an ohm meter. If those speakers are 8 ohm then the DC resistance should be somewhere between 6 and 7.25 ohms most likely.

If the resistance you measure is very low, then the voice coils are fried. If on the other hand it is normal, and you hear a good click as you connect your meter, then there is a crossover problem.

Please post back and let us know what you find out.

 

[R-Carpenter]

Small correction. The DC resistance of the tweeter in a 8ohm system can very easily be 3 or 4 ohm.(Efficient tweeter with L-pad in the crossover) Unless Rock is capable of dissecting the crossover or the tweeters will show some weird impedance like 30ohm he is not going to do much by himself. But never the less, measure the DC resistance and post the results.
http://www.partstore.com/Model/Sony/Sony/SSAV55.aspx?UTM_Source=Google&UTMCampgain=ModelNumber_BestSellersUTM_AdGroup=Home Audio & Speakers
In case you decide to replace the tweeter.
It could be bad parts in the crossover. Electrolytic caps do go bad and cheap resistors fry.
Maybe
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=071-254
or something similar is bad?

 

[TLS Guy]

Small correction. The DC resistance of the tweeter in a 8ohm system can very easily be 3 or 4 ohm.(Efficient tweeter with L-pad in the crossover) Unless Rock is capable of dissecting the crossover or the tweeters will show some weird impedance like 30ohm he is not going to do much by himself. But never the less, measure the DC resistance and post the results.
http://www.partstore.com/Model/Sony/Sony/SSAV55.aspx?UTM_Source=Google&UTMCampgain=ModelNumber_BestSellersUTM_AdGroup=Home Audio & Speakers
In case you decide to replace the tweeter.
It could be bad parts in the crossover. Electrolytic caps do go bad and cheap resistors fry.
Maybe
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=071-254
or something similar is bad?

Well done, if he does need parts you have found the exact replacement.
If the voice coils are fried the impedance usually drops to an ohm or less and the other thing is the the tweeters will almost certainly give different readings.

 

[R-Carpenter]

Well done, if he does need parts you have found the exact replacement.
If the voice coils are fried the impedance usually drops to an ohm or less and the other thing is the the tweeters will almost certainly give different readings.

Thanks. It's a bit strange that he's getting same problem with both tweeters. Blown at the same time?
As far as I remember, Sony uses lower cost Vifa tweeters.

 

[rockblock]

...partstore.com/Model/Sony/Sony/SSAV55.aspx?UTM_Source=Google&UTMCampgain=ModelNumber_BestSellersUTM_AdGroup=Home%20Audio%20&%20Speakers
In case you decide to replace the tweeter.

BINGO !!! that's the one....but $46 for both drivers + shipping....yikes...(paid less for the speakers lol). I'll need to do some more research...

I have one more question : if I'd be looking for a non-stock replacement, what power should I be looking for the tweeter to handle? Between the 3 drivers (2 woofers + 1 tweeter), I assume that the power is not distributed evenly amongst the 3...so, what ratio should I be using?...would it be a good guess to say that 40% + 40% + 20% (tweeter)? If so, would that mean I would be looking at something like this:

- 8 ohms
- 25-35W
- 87-92dB

PS. Does it matter if I replace them with cones, or should I stick to domes?

Thx again, great advice !

 

[rockblock]

Thanks. It's a bit strange that he's getting same problem with both tweeters. Blown at the same time?
As far as I remember, Sony uses lower cost Vifa tweeters.

The previous owner told me that a few years ago he had an issue with one of the woofers and that Sony replaced it for him...maybe it was then that the tweeters got busted too...hard to figure how come he never noticed it though...anyways, they need to be replaced...

 

[TLS Guy]

BINGO !!! that's the one....but $46 for both drivers + shipping....yikes...(paid less for the speakers lol). I'll need to do some more research...

I have one more question : if I'd be looking for a non-stock replacement, what power should I be looking for the tweeter to handle? Between the 3 drivers (2 woofers + 1 tweeter), I assume that the power is not distributed evenly amongst the 3...so, what ratio should I be using?...would it be a good guess to say that 40% + 40% + 20% (tweeter)? If so, would that mean I would be looking at something like this:

- 8 ohms
- 25-35W
- 87-92dB

PS. Does it matter if I replace them with cones, or should I stick to domes?

Thx again, great advice !

Don't even think about looking for a different tweeter, you will be in a pile of hurt. Anyhow, how do you know it the tweeters? It is more likely to be the caps.

 

[R-Carpenter]

Oh boy.
If you want to have a coherent sounding loudspeaker, you cannot replace the tweeter based on this “calculations”. Drivers for the speaker are selected based on multitude of electromechanical parameters.
You can call here: http://www.madisound.com/index.php
or here: http://www.parts-express.com
and may be by, some bazaar coincident, they would know a cheap replacement tweeter.

I am not trying to be sarcastic here but what you asking is: can I put Chevy LS1 heads on Nissan VG30DETT block.

If you don't care how it is going to sound in the end and your speakers (with all due respect) aren't the cream of the crop out there, just get the cheapest tweeters you can find, (same size front plate), throw them in there and take a chance. It may or may not work and you'd spend $20 with the shipping anyhow.

At list start with measuring DC resistance of the tweeters you have and as TLS pointed out, figure out if it's tweeters at all. And pleas try not to connect them straight to speaker wire to see if they are working. If you do, I am pretty sure they will fry if they aren't already.
Step by step. You need DMM for starters.

 

[rockblock]

Don't even think about looking for a different tweeter, you will be in a pile of hurt. Anyhow, how do you know it the tweeters? It is more likely to be the caps.

Do I have any way of telling whether it's the cap or not?...the driver seems to be compact and sealed along with the magnet on the back

 

[rockblock]

Oh boy.
If you want to have a coherent sounding loudspeaker, you cannot replace the tweeter based on this “calculations”. Drivers for the speaker are selected based on multitude of electromechanical parameters.
You can call here: http://www.madisound.com/index.php
or here: http://www.parts-express.com
and may be by, some bazaar coincident, they would know a cheap replacement tweeter.

I am not trying to be sarcastic here but what you asking is: can I put Chevy LS1 heads on Nissan VG30DETT block.

If you don't care how it is going to sound in the end and your speakers (with all due respect) aren't the cream of the crop out there, just get the cheapest tweeters you can find, (same size front plate), throw them in there and take a chance. It may or may not work and you'd spend $20 with the shipping anyhow.

At list start with measuring DC resistance of the tweeters you have and as TLS pointed out, figure out if it's tweeters at all. And pleas try not to connect them straight to speaker wire to see if they are working. If you do, I am pretty sure they will fry if they aren't already.
Step by step. You need DMM for starters.

Well, I only have a multimeter so I'll start with checking the impedance...thx for the "speaker primer", I though it would be much simpler...lol

 

[rockblock]

Update

I've managed to get a hold of the manual that provides some additional info on the speakers (not sure if this can provide any additional help for the tweeters though):

Speaker specs:

Woofers: 6.5" cones x 2
Tweeter: 1" dome
Freq. response: 30-20kHz
Impedance: 8 ohms
Sensitivity: 91 dB SPL , 1W measured @ 1m
Power handling: 130W

I'm not sure if the sensitivity gives us more insight, but I thought I'd share

Thx

 

[TLS Guy]

I've managed to get a hold of the manual that provides some additional info on the speakers (not sure if this can provide any additional help for the tweeters though):

Speaker specs:

Woofers: 6.5" cones x 2
Tweeter: 1" dome
Freq. response: 30-20kHz
Impedance: 8 ohms
Sensitivity: 91 dB SPL , 1W measured @ 1m
Power handling: 130W

I'm not sure if the sensitivity gives us more insight, but I thought I'd share

Thx

That really does not help us much. The original advice still stands.