Speaker noises

[Edward Huggins]

These speakers were indeed rather poor. The driver units were (but not always) bog standard Goodmans commercial units with very basic 2 element crossovers. They gave a rather "one note" bass. Their rival company "Period High Fidelity" (also based in Maidenhead) used Peerless drive units and their speaker designs were far superior.
I nearly lost my job with Pye (who owned them) complaining about poor quality standards! Have many Members have noticed just how many Dynatron units suffer from frequent failure in one channel of their audio stages......?

[19Seventy7]

Originally Posted by crackle

Have you had these speakers long, do you know their history?
I wonder if they could have been poorly re-coned in the past.

Another thing to check is the inner suspension by the voice coil, has this come away from the speaker frame.
Does the speaker cone make a scratching noise when you push it with evenly spaced pressure.

I've had them for around a year and a half now, and I have no idea of their history, bought them just being told the basics and that the system (Player and speakers) is in working order.

I can apply test them now and i'll get back with the results.

Originally Posted by snowman_al

Can you clarify a couple of things please?
Is it one or both speakers with the 'sparking' noise?
You say it / they make a noise when not playing music sometimes. Now you have the covers off can you watch the cones and see if they are moving in and out with nothing playing. Try different positions of the volume control too.
Do you have other speakers to try to make sure the amplifier or cables are not to blame?

I believe it's only both, but im not 100% too sure on this. I'll take the covers off again and put the volume up and watch, and I'll get back with the results from that too.

I don't have any other speakers, nor cable. Just the two that I bought originally.

Originally Posted by Techman

I've got a pair buried somewhere in the loft and I can tell you that they don't like a lot of "Quo" through them at high volume, even when powered by the original Dynatron system they came with, and are likely to make the noises you describe after such an event

I could also tell you that they don't seem to like a lot of Queen being played at a high volume either, which is unfortunate for them.
I would say that they sound quite decent, but I've never had another pair to compare them too.
Thank you all for your help, i'll get to testing now.

Thanks.

[19Seventy7]

It turns out it is both speakers, but the left being much worse. The left pops and scratches, while the right just scratches with no music, and on full volume.

When I first turn the system on, it's the worst, lasting around 3 to 5 seconds, before dying down, just to do randomly do so with use, or just being powered on.

Thanks

[Nuvistor]

With the description of those noises are you sure it’s the speakers and not two faulty amplifiers. With no drive, I.e, no music and full volume there should be virtually no signal being fed to the speakers to move the voice coils, perhaps just a small amount of noise (hiss).
Noisy volume controls could well produce those symptoms.

[snowman_al]

Now what happens if you swap the left and right speakers round?
Does the 'pops and scratches' sound move to the other speaker?

This will help identify if the problem is the speakers or an amplifier fault, poor switch contact or volume control etc..
Alan

PS, just re-reading your initial post about 2 different amplifiers. Can you do the same test again with the other amplifier too?

[crackle]

I think we need to establish if the cone is moving in and out freely with no rubbing and if the inner suspension is attached. The inner suspension cant really be checked without taking the speaker out of the cabinet and looking from the side of the speaker at the inner end of the diaphragm cone.
Move the diaphragm in and out to its full extension and see if the inner suspension comes away from the chassis.
At the same time listening for any scratching or rubbing noise.
I dont know the construction of these speaker drivers but I have seen a voice coil become loose on the coil former and slide on it, that would produce the type of noise you describe.
I am not too sure how you would test for that.

But if the speaker is OK then the problem is probably in the amplifier. Possible causes dirty/worn controls, dry joints, leaky/breaking down transistors or other components.

Mike

[19Seventy7]

Hi again,

It's been a while since I made this thread, but I just stopped using the record player and speakers as I couldn't sort them out.

I made a discovery last night that it is the record player, and not the speakers, and only the left channel is affected by the noise. I plugged in my headphones, and got the sound from them too, which I then realised it wasn't the speakers.
Both right channels work fine, the left channels is what has the interference.

Does anyone know what this is? I assume it'll be something to do with the left amplifier?

Thanks

[Edward Huggins]

It is often all too easy to assume that the problem in these cases will lay with the speakers, but experience shows this will rarely be the case.
Before we consider an amplification failure, are you completely sure that the lack of sound on the left hand channel occurs on BOTH Radio and Record reproduction?

[19Seventy7]

Hi,
I’ve just tried the record, radio and tape in put and all three have the noise on the left hand channel. Roght hand is fine, still on all three. Changing the speaker input from main to remote makes no difference either.

Thanks

[Edward Huggins]

We are still not sure if you have swapped the speaker leads over or tested on a battery as previously advised. Did you try this? If both speakers do prove to be working, then this sounds like a fault in the amplifier channel whether it be the electronics or some form of switching oxidisation. Is this something you would be prepared to troubleshoot and try to fix for yourself?

[19Seventy7]

Hi, yes sorry I should've said I did try with switching the cables round and the speakers are fine, both are working, and only omit the noise when plugged into the LH channel.
I'm more than happy to fix it, but im not too sure what i'd be looking for inside, I can take a photo of the electronics inside tomorrow if it will be of any help?
Edit: I have no way of testing it on battery. Mains interference did cross my mind, but it was working properly for sometime before.

Thanks

[19Seventy7]

Hi,

I was using my record player today, (Using both RH channels) and I stopped using it for a second, and so just stopped the music, but didn't turn the player off with the intention of using it again. I completely forgot about it when I just hear a pop and crackle. I quickly turned it all off and unplugged it. I felt the TT was quite warm, which was odd.

I've now taken the bottom off to see if anything had literally popped, but I cannot see anything. However, there is a small resistor or diode which looks like it's melted onto other components (I apologise, I don't know the correct terms properly) there are also other components which look to have melted together. The other PCB wasn't anywhere as warm, nor does it have the melted look on the respective parts.

These are on a small circuit (one of a pair, which I assume make up part of the amplifier etc) This is very warm to the touch (the other part isn't) and is directly under the warm part of the TT.

I lifted the PCB out of it's holder and looked on the underside, all the soldering seems to have a brown substance.

Could it've been the resistor/diode has failed, and is heating up the rest of the components.

Thanks

[music-centre]

The brown around the solder joints on the underside is just Flux residue and the material between the components on the other side looks to be around a lot of them, perhaps it was put on to keep components together when the boards were machine soldered?
Steve.

[Refugee]

It looks like wax to me.
If it is still on there it has not been hot enough to worry about.
The click must have been thermostat noise from something external to the record player.

[19Seventy7]

Oh that makes sense about the flux or wax, i'll ignore that then. The click was definitely inside the record player, as it's right behind me and the plug socket is a bit further away to my right, it was definitely inside the record player. I haven't turned it on obviously until I know what im dealing with

Thanks

[Refugee]

Thermostats do make clicks on audio equipment all the time.
I would guess that if you left it on and listened you would be able to find something close by such as a fridge that starts or stops when you hear the click.

[music-centre]

Originally Posted by 19Seventy7

Hi,

I was using my record player today, (Using both RH channels)

Hi,
You say using both RH channels but if you had one speaker plugged in to the main and the other in the remote speaker sockets they effectively would be in parallel on the one working channel and it may not have liked the reduced Impedance causing damage to it - I don't think it is anything you can see in the pictures though.

Up to you, but I think I would be inclined to quickly test it with one speaker on the previously working channel to see what you get.
Steve.

[ekjdm14]

As per the other replies I can't see anything obviously blown/melted, the components on that PCB wouldn't generally melt, rather char or blow apart & as the (presumed) wax appears not to have melted I wouldn't think those parts have been very hot.

I'd tend to suggest the heat has come from the output transistors (large T03 packages on the heatsink plate) having not enjoyed driving too little impedance as alluded to above.

At this stage I'd say do the same, see if it still works, since likely any damage would have been done. On the other hand, it'd be safer to do some diagnostics first in case one of the outputs has shorted. Firstly are all fuses intact? secondly, do any of the T03 transistors show as shorted? Possibly worth powering up with no speaker connected (provided it's OK on this amp to do so) and checking for any DC voltage on the output terminals.

What are the outputs on this? Number on the case beginning with AC? Just recently come across a germanium output that leaked & shorted as it warmed up so possible it temporarily shorted if it overheated?