Marantz 1090 crackling sound problem

[playman]

Hello badcappers

I have a problem with my sound system.
I have a Marantz model 1090 connected to my pc, and to the amp I have
connected 2x Sony "SS-WS9" 4ohm woofers to left 1 and left 2
and 2x "philips 70fb565/o2p" 4-8 ohm to right 1 and right 2.

Here is a video of the sound.
https://app.box.com/s/bsudwodwf58ztf60mdyr

It's kinda hard to describe, but when I plug the second woofer to the amp
the crackling starts when I increase the volume, the crackling sounds in both of the
woofers, when I unplug the woofer the crackling stops.
I did not hear any crackling in the other speakers.

Any one know what's wrong?

[playman]

Re: Marantz 1090 crackling sound problem

no one?

[lexwalker]

Re: Marantz 1090 crackling sound problem

I have a problem with my sound system.
I have a Marantz model 1090 connected to my pc, and to the amp I have
connected 2x Sony "SS-WS9" 4ohm woofers to left 1 and left 2
and 2x "philips 70fb565/o2p" 4-8 ohm to right 1 and right 2.

Here is a video of the sound.
https://app.box.com/s/bsudwodwf58ztf60mdyr

It's kinda hard to describe, but when I plug the second woofer to the amp
the crackling starts when I increase the volume, the crackling sounds in both of the
woofers, when I unplug the woofer the crackling stops.
I did not hear any crackling in the other speakers.

Any one know what's wrong?

Could be amplifier drive power overload. Anyway, those outputs are for 8 ohms impedance. You could try adding an additional 4 Ohm resistor (must be at least 2W or higher) in series with each speaker that has 4 Ohm impedance...

[budm]

Re: Marantz 1090 crackling sound problem

You are loading the output with less than 4 Ohms, it just cannot handle it. You will damage the output circuits.

[playman]

Re: Marantz 1090 crackling sound problem

Could be amplifier drive power overload. Anyway, those outputs are for 8 ohms impedance. You could try adding an additional 4 Ohm resistor (must be at least 2W or higher) in series with each speaker that has 4 Ohm impedance...

Do you have any idea where I might be able to salvage those resistors from?
there is no spare parts store in my town and ordering 2 resistors is
just to expensive, and since I get my hands on quite a lot of electronics
salvaging should not be a problem.

You are loading the output with less than 4 Ohms, it just cannot handle it. You will damage the output circuits.

Less then 4 Ohms? each woofer is 4 Ohms and I have them connected
in their separate output channel.
I don't have them connected in series or parallel, or am I misunderstanding something?

Wild Idea, since they have to be 8 Ohms can I connect them in series to make them 8 Ohm?
Or will that be to much for the output channel to handle?

[lexwalker]

Re: Marantz 1090 crackling sound problem

Do you have any idea where I might be able to salvage those resistors from?
there is no spare parts store in my town and ordering 2 resistors is
just to expensive, and since I get my hands on quite a lot of electronics
salvaging should not be a problem.

Try looking at switching power supplies (especially computer ones). At the output side, often they have a dummy load resistor. If lucky can find some around 10 Ohms, which can be wired in parallel to create a 5 Ohm resistor. If want more precise value (of 4 Ohms) then parallel another resistor around 20 Ohms.

[playman]

Re: Marantz 1090 crackling sound problem

Tanks for the answer lexwalker.
I've salvaged the required resistors I needed.
I've measured the Ohms out of the woofers, and 1 is 8.1 Ohm and other is 7.6 Ohm.

Yet still I'm experiencing the same crackling noise, not quite sure, but I think I can get higher volume until the crackling starts.
Do I need to ad more Ohms to the speakers or is there something broken in the amp?
As I'm not the original owner, I've no idea of the treatment from the previous owner.

[lexwalker]

Re: Marantz 1090 crackling sound problem

Tanks for the answer lexwalker.
I've salvaged the required resistors I needed.
I've measured the Ohms out of the woofers, and 1 is 8.1 Ohm and other is 7.6 Ohm.

Yet still I'm experiencing the same crackling noise, not quite sure, but I think I can get higher volume until the crackling starts.
Do I need to ad more Ohms to the speakers or is there something broken in the amp?
As I'm not the original owner, I've no idea of the treatment from the previous owner.

Then better check the connections, contacts and soldering joints first (on the speakers and amplifier terminals). The crackling could be a sign of insufficient power supply, thus check the components in the amplifier, particularly the power supply board (and especially the capacitors). Also check the decoupling capacitors, as well as any output coupling capacitors. Plus at the output side, look for stability resistor-capacitor combos (which is used to prevent oscillations).

[playman]

Re: Marantz 1090 crackling sound problem

Then better check the connections, contacts and soldering joints first (on the speakers and amplifier terminals). The crackling could be a sign of insufficient power supply, thus check the components in the amplifier, particularly the power supply board (and especially the capacitors). Also check the decoupling capacitors, as well as any output coupling capacitors. Plus at the output side, look for stability resistor-capacitor combos (which is used to prevent oscillations).

Thank you lexwalker, i'll start checking that out when I have my replacement amp ready.
Just two things, what are coupling capacitors and a resistor capacitors?
Are they any different then normal capacitors?

[lexwalker]

Re: Marantz 1090 crackling sound problem

Thank you lexwalker, i'll start checking that out when I have my replacement amp ready.
Just two things, what are coupling capacitors and a resistor capacitors?
Are they any different then normal capacitors?

Coupling capacitors are those directly in the audio path (sometimes known as D.C blocking capacitors). Usually you can find them in preamp stages, as well as output stages (for power amplifiers with single supply). That resistor-capacitor combo is also known (in technical terms) as Zobel network. Depending on amplifier design, you can find them at the output section of the power amplifier stage.

[budm]

Re: Marantz 1090 crackling sound problem

When you have speakers selector switch set to 1 (speaker set #1 L&r) + 2 (speaker set #2 L&R), that will put speakers 1 and 2 in parallel. I.E. speaker 1 left = 8 Ohms, Speaker 2 left = 8 Ohms, total load for the left amp will be 4 Ohms. The lower the Ohms the more current it will try to draw from the amp.

[playman]

Re: Marantz 1090 crackling sound problem

When you have speakers selector switch set to 1 (speaker set #1 L&r) + 2 (speaker set #2 L&R), that will put speakers 1 and 2 in parallel. I.E. speaker 1 left = 8 Ohms, Speaker 2 left = 8 Ohms, total load for the left amp will be 4 Ohms. The lower the Ohms the more current it will try to draw from the amp.

So are you saying that since I have those speakers and woofers connected
I'm putting 4 Ohms on the amp?
Does that mean that I should increase the Ohms of the speakers and woofers to 16 Ohms so the
total Ohms of the amp would total to 8 Ohms?
Or am I misunderstanding something?
Sorry for my newbiesm.

[playman]

Re: Marantz 1090 crackling sound problem

no answer to my last question?

[rhomanski]

Re: Marantz 1090 crackling sound problem

The total resistive load needs to be 8 ohms ideally. Hooking loads in parallel, which is what you do when you use all the outputs on an amp will lower the total resistive load. Sometimes too low. I hear you about stores in Iceland. I was there once in the eighties. Beautiful place. I stayed at the blue lagoon, Vid Blaa Lonid, I think IIRC.

That Marantz is a beautiful unit but very old. It should have a total rebuild to sound it's best. Your problem could lie in that direction but nonetheless, You can't go below 4 ohms without damaging the unit. Just use the speakers you can and don't connect more than it can use.

[playman]

Re: Marantz 1090 crackling sound problem

The total resistive load needs to be 8 ohms ideally. Hooking loads in parallel, which is what you do when you use all the outputs on an amp will lower the total resistive load. Sometimes too low. I hear you about stores in Iceland. I was there once in the eighties. Beautiful place. I stayed at the blue lagoon, Vid Blaa Lonid, I think IIRC.

That Marantz is a beautiful unit but very old. It should have a total rebuild to sound it's best. Your problem could lie in that direction but nonetheless, You can't go below 4 ohms without damaging the unit. Just use the speakers you can and don't connect more than it can use.

Thanks for the reply.
Yes the blue lagoon is called Bláa lónið, it's really beautiful place but has gotten pretty pricey today

I just wanted to use the 4 ports that the amp had and use the 4 speakers that I have here, I guess I have to change that setting.

You mention a total rebuild of the amp, what does that mean?
Just replace all caps or something more drastic then that?

[rhomanski]

Re: Marantz 1090 crackling sound problem

Replacing all the electrolytic caps is a start. You need to replace the heat sink grease and clean all the switches and controls and perhaps the diodes and some transistors. At least the protection relay and associated circuitry. The relay gets old and crusty, it can be cleaned but will eventually fail. The magnetic field will send a pulse back when it collapses so after about 76 manufacturers started putting a diode to block it. That reverse flow burned out a lot of transistors. Even diodes though have only a limited PN junction and will eventually fail. If you look at the junction under an electron microscope you will see craters where the junction is destroyed. When the destruction is complete the diode fails. Also some transistors from the period have proven themselves to be unreliable. The 2sa725 and 726, 2sc1312 and others.

[playman]

Re: Marantz 1090 crackling sound problem

Thank you rhomanski for that detailed reply.
The first thing I did when I received the amp was to clean the switches/controls, got them all pretty good
except for the selector switch, I sometimes have to touch it to get full audio.
I guess next I'll take the caps and thermal paste, is it ok to use CPU thermal paste?
Transistors and diodes will have to wait, unless I'm able to salvage some diodes here.
I only finished 2 semesters in electronics in school, so my knowledge is somewhat limited regarding the rest of the rebuilding process.

Now I haven't looked into the amp recently, but if there are ceramic or any other kinds of cap's
can I change them for electrolytic caps of same rate?
And would that have any significance impact on the audio?

[rhomanski]

Re: Marantz 1090 crackling sound problem

I have heard both ways on thermal grease. Some said don't use computer grease some have said they do and don't have any problem.

Electrolytic caps are one way. That is to say they have a positive and a negative lead. Others don't. So you would have to use a bipolar electrolytic which are more rare. Also the other kinds usually have lower noise. Depending on where you use electrolytics you can add hiss. I usually try to replace kind with kind wherever possible. Even replacing transistors can get hairy. I was recently replacing transistors in my tuner and had a few left of one type. I ordered more of the same kind and later found out the manufacturer had changed the base and collector lead. Took me a while to find all the problems that caused.

[rhomanski]

Re: Marantz 1090 crackling sound problem

Some people have used the cpu grease and said they had no problem.

You would have to use a bipolar electrolytic probably and they may add hiss. Use kind for kind whenever possible. There are a lot of considerations when substituting. If you guess wrong you could get a destructive oscillation and burn out more than you can fix easily. Only the electrolytic capacitors need to be changed. They will dry out over time. Ceramic and what have you will last a lot longer.