Amplifier ~ Weird Issue

[Stiggie]

Hello,

A couple of years ago I bought a simple Yamaha AX-570 Amplifier from Ebay, to connect it to my Magnat All-Ribbon 8 Speakers.

I worked incredibly well, worked...


6 Months ago the sound quality became suddenly horrible. Other people don't notice it, but I can't enjoy my music anymore. It seems all muffled and the music has lost all it's dynamics. It sounds worse then a 30$ computer speakers, especially when the volume is low. And it all happend suddenly, one day it was ok, the next day it was horrible.

I know that it's an issue with the amplifier, not the speakers. (Have tested with another amplifier)

So for 6 months I've been trying to fix it, but nothing seems to solve the problem, you seem to be my last hope.

Sincerely Regards

 

[KEW]

Hello,

A couple of years ago I bought a simple Yamaha AX-570 Amplifier from Ebay, to connect it to my Magnat All-Ribbon 8 Speakers.

I worked incredibly well, worked...


6 Months ago the sound quality became suddenly horrible. Other people don't notice it, but I can't enjoy my music anymore. It seems all muffled and the music has lost all it's dynamics. It sounds worse then a 30$ computer speakers, especially when the volume is low. And it all happend suddenly, one day it was ok, the next day it was horrible.

I know that it's an issue with the amplifier, not the speakers. (Have tested with another amplifier)

So for 6 months I've been trying to fix it, but nothing seems to solve the problem, you seem to be my last hope.

Sincerely Regards

What have you done to try to fix it?
That is an older unit and the capacitors may have gone bad. I think you'd need to take it in to the shop, but be prepared that the cost of repair may exceed what you paid on ebay.
Most importantly, don't crank it until you have resolved the issue! My understanding is that you most likely have a pre-amp issue now, but if you drive things hard while in this condiiton, you can lose the main amp.

 

[Stiggie]

What have you done to try to fix it?
That is an older unit and the capacitors may have gone bad. I think you'd need to take it in to the shop, but be prepared that the cost of repair may exceed what you paid on ebay.
Most importantly, don't crank it until you have resolved the issue! My understanding is that you most likely have a pre-amp issue now, but if you drive things hard while in this condiiton, you can lose the main amp.

I've tried to use it as end-amp only, same issue.
Have opened it multiple times to verify the components (+pressured air), but couldn't find anything.
Problem appears on every source-input.



edit: I feel kinda stupid, I just put my head to each of the 3 cones of the speaker. There doesn't seems to come anything out of the tweeters =S (on both). I suppose the amplifier blowed up the tweeters. (Sometimes when I turn on the amplifier, I hear a really loud weird noise and the bass cone just moves back and forth very slowly (almost an inch). =S

Repairable?

 

[TLS Guy]

What have you done to try to fix it?
That is an older unit and the capacitors may have gone bad. I think you'd need to take it in to the shop, but be prepared that the cost of repair may exceed what you paid on ebay.
Most importantly, don't crank it until you have resolved the issue! My understanding is that you most likely have a pre-amp issue now, but if you drive things hard while in this condiiton, you can lose the main amp.

There is a service manual available here. However it is a RAR file, and I can't open it.

Since this problem involved both channels, this problem has to be in the power supply. I would think that for some reason the voltage from the power supply has become seriously reduced, possibly because of the failure of a regulator or something like that.

Do not use the unit at all in its current condition.

 

[valvesnvinylfan]

I've tried to use it as end-amp only, same issue.
Have opened it multiple times to verify the components (+pressured air), but couldn't find anything.
Problem appears on every source-input.



edit: I feel kinda stupid, I just put my head to each of the 3 cones of the speaker. There doesn't seems to come anything out of the tweeters =S (on both). I suppose the amplifier blowed up the tweeters. (Sometimes when I turn on the amplifier, I hear a really loud weird noise and the bass cone just moves back and forth very slowly (almost an inch). =S

Repairable?

HI, I know earlier you had mentioned you tried the speakers with different amp and they worked fine; but now it sounds like the tweeters are blown, when they weren't on the other amp you tried, correct?

 

[highfigh]

Hello,

A couple of years ago I bought a simple Yamaha AX-570 Amplifier from Ebay, to connect it to my Magnat All-Ribbon 8 Speakers.

I worked incredibly well, worked...


6 Months ago the sound quality became suddenly horrible. Other people don't notice it, but I can't enjoy my music anymore. It seems all muffled and the music has lost all it's dynamics. It sounds worse then a 30$ computer speakers, especially when the volume is low. And it all happend suddenly, one day it was ok, the next day it was horrible.

I know that it's an issue with the amplifier, not the speakers. (Have tested with another amplifier)

So for 6 months I've been trying to fix it, but nothing seems to solve the problem, you seem to be my last hope.

Sincerely Regards

Have you heard any scratchiness when you adjust the controls and switches, or are they never changed? If you never use them, I would try cleaning them all. A tone bypass switch, speaker or source selector switch or if you're using a previously untouched area of the volume control, it could be that.

Or, as TLS mentioned, it could be the power supply.

However, now that you mentioned that the tweeters appear to be bad, you need to know that ribbon drivers aren't always capable of handling high power and they definitely don't like a lot of distortion.

 

[TLS Guy]

HI, I know earlier you had mentioned you tried the speakers with different amp and they worked fine; but now it sounds like the tweeters are blown, when they weren't on the other amp you tried, correct?

Oh dear! I suspect the voltage from the power supply was indeed low resulting in clipping at quite low volumes, causing failure of the tweeters. I don't believe that speaker company are still in business, but I could be wrong on that. If they are out of business, you are looking at building a system from ground zero pretty much

From your description of the woofer movement, it sounds as if the amp was letting through DC off set to the speakers, which a decent amp should never do. For me that would not tempt me to get the amp repaired. I would get something better.

 

[highfigh]

DC offset can just be a matter of an adjustment or if the amp is old enough and it sat for a long time, the filter caps are possibly bad. If you're particularly attached to the amp, you could repair it but it may be one of those situations where the cost would be more than it's worth. Fortunately, many amps that will do the job are easily available but that won't bring your tweeters back.

 

[Stiggie]

HI, I know earlier you had mentioned you tried the speakers with different amp and they worked fine; but now it sounds like the tweeters are blown, when they weren't on the other amp you tried, correct?

True, I also tested the amp with other B&W speakers. I've done that a couple of months ago, so I can't really tell what went wrong within my head. I think I might have been too objective, about thinking that it was just the amplifier that had a problem. I'm very sorry about that.

I've opened the tweeter, the cone itself is fully intact. It's the voicecoil wire that seems to have burned out (there's a brown liquid all over it). I suppose that it isn't repairable.


I feel bad about having to throw those incredible good speakers out of the window, just because of such a small problem =(.

 

[TLS Guy]

True, I also tested the amp with other B&W speakers. I've done that a couple of months ago, so I can't really tell what went wrong within my head. I think I might have been too objective, about thinking that it was just the amplifier that had a problem. I'm very sorry about that.

I've opened the tweeter, the cone itself is fully intact. It's the voicecoil wire that seems to have burned out (there's a brown liquid all over it). I suppose that it isn't repairable.


I feel bad about having to throw those incredible good speakers out of the window, just because of such a small problem =(.

The brown liquid is the ferrofluid, that cools the voice coil. You should have tested the tweeter with a multimeter, not opened it up!

I though those were ribbon speakers, it sounds like they are not. Is there a manufacturers name on the tweeter, and a model number?

I don't understand how you have blown two tweeters, unless there is something wrong with the amp, or you play music far too loud.

 

[Stiggie]

The brown liquid is the ferrofluid, that cools the voice coil. You should have tested the tweeter with a multimeter, not opened it up!

I though those were ribbon speakers, it sounds like they are not. Is there a manufacturers name on the tweeter, and a model number?

I don't understand how you have blown two tweeters, unless there is something wrong with the amp, or you play music far too loud.

The speakers are called "Magnat all ribbon 8", but the tweeter is just a 1" textile dome tweeter, same kind as this tweeter:

h**p://soundt.18.forumer.com/index.php?showtopic=908

(not a high enough postcount to post links)

No harm has been done by opening the tweeter, pretty sure of that. I also took a look at the crossover; no blown caps or anything like that. But it's true, I should have tested it with a multimeter first.

I'll post some photos of the tweaker, and the resistance of the voice coil. Should be around 5-6 ohms, right?

 

[TLS Guy]

The speakers are called "Magnat all ribbon 8", but the tweeter is just a 1" textile dome tweeter, same kind as this tweeter:

h**p://soundt.18.forumer.com/index.php?showtopic=908

(not a high enough postcount to post links)

No harm has been done by opening the tweeter, pretty sure of that. I also took a look at the crossover; no blown caps or anything like that. But it's true, I should have tested it with a multimeter first.

I'll post some photos of the tweaker, and the resistance of the voice coil. Should be around 5-6 ohms, right?

If its an 8 ohm tweeter it will be around 7 ohms or a little less. If four ohm around 3.

 

[Magnat10]

re: Magnat all ribbon 8

Stiggie, I have a few pairs of Magnat All Ribbon series myself 10's, 6's, 7P's and Dahlquist DQM9C <rebadged Magnat all ribbon>
The best were made late 70's early 80's later on the quality dropped as Recoton purchased them. The "all ribbon wire" refers to flat aluminum wire used on the coils of the drivers, computer wound the flat wire leaves no air gaps like round wire and you get more mass in the coil which increases the reponse. They also are very efficient in the low to mid 90 db range depending on unit and if you have no clipping indicators on your amp you likely exceeded it's capability. I run my Magnat all ribbon 10's on a Bryston 3B amp with Bryston .5B pre amp, the amp was tested at Bryston April 2006 and pushes 135 wpc at clipping. Thinking of my volume dial on the .5B as a clock face with 7 o'clock as 0 my clipping indicators go from green to red between 9 and 9:30, on other speakers it's usually 12 to 12:30. I don't listen at these levels but always check the ceiling to set the amp at a safe level.
You cannot buy replacement drivers from the manufacturer anymore thay have long since been discontinued, buying them on Ebay you will only find them in Europe and expect a fight if they are the sought after ones. I tried 4 times to get myself a good pair for spares and they cost me $180 plus shipping, at 5 seconds left on the auction my bid was $80. I will send you some spec info and pics of my mags, if I can help you finding new tweets please ask if you are interested in repairing them.