Speaker Popping

[Don]

I was given this old Playmaster 40/40 amplifier to fix some hum problems
which I have solved but there is another problem I have found, but could be
a design fault, if another electrical device, ie a light on the same ac
mains circuit is switched on it produces a loud pop in the speakers. I have
also noticed that there is a loud pop when the amplifier is switched on as
well. How can I fix this?

 

[Tom MacIntyre]

I was given this old Playmaster 40/40 amplifier to fix some hum problems
which I have solved but there is another problem I have found, but could be
a design fault, if another electrical device, ie a light on the same ac
mains circuit is switched on it produces a loud pop in the speakers. I have
also noticed that there is a loud pop when the amplifier is switched on as
well. How can I fix this?

Could be bad coupling capacitors in the outputs feeding the speakers.
For both to have the same problem is unlikely, although it's possible
for an old amplifier. May be just poor design.

Tom

 

[Kevin McMurtrie]

I was given this old Playmaster 40/40 amplifier to fix some hum problems
which I have solved but there is another problem I have found, but could be
a design fault, if another electrical device, ie a light on the same ac
mains circuit is switched on it produces a loud pop in the speakers. I have
also noticed that there is a loud pop when the amplifier is switched on as
well. How can I fix this?

Check it on an o'scope to see if the amplifiers are under biased or
under compensated, making it very susceptible to spurious oscillation.
There may also be remaining problems related to what was causing the hum.

 

[James Meyer]

I was given this old Playmaster 40/40 amplifier to fix some hum problems
which I have solved but there is another problem I have found, but could be
a design fault, if another electrical device, ie a light on the same ac
mains circuit is switched on it produces a loud pop in the speakers. I have
also noticed that there is a loud pop when the amplifier is switched on as
well. How can I fix this?

Does the pop when external devices are turned on or off happen when
there is absolutely nothing plugged into any of the amp's input jacks?

The pop when the amp is turned on is something that happens "normally"
to many older amps.

Jim

 

[Jerry G.]

Many of the older amplifiers, and some of the very high power amplifiers
do not have a delayed muting relay on the output. Many of the consumer
type amplifiers have this type of relay to not allow the speakers to be
connected until the power supply and output stage are fully started up.
The speakers are therefore not connected until the amp is properly
started.

What you can do is leave the speakers in the off position for about 10
seconds after turning on the amplifier. If here are no speaker
switches, you can wire some external switches and mount them in a box on
the side.

Or, you can do what I do, is to leave the amp on 24/7. I found that
overall there were less problems with this type of practice.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
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I was given this old Playmaster 40/40 amplifier to fix some hum problems
which I have solved but there is another problem I have found, but
could be
a design fault, if another electrical device, ie a light on the same ac
mains circuit is switched on it produces a loud pop in the speakers. I
have
also noticed that there is a loud pop when the amplifier is switched on
as
well. How can I fix this?

 

[N. Thornton]

The pop when the amp is turned on is something that happens "normally"
to many older amps.

Exactly. It just indicates lack of PSU regulation and low PSU noise
rejection. Simplest solution is a 0.22uF cap across the mains
transformer secondary, and another one on the PSU rail near the
amplifier. Usually that will de-pop it reasonably well.

Regards, NT

 

[ånønÿmøu§]

I was given this old Playmaster 40/40 amplifier to fix some hum problems
which I have solved but there is another problem I have found, but could be
a design fault, if another electrical device, ie a light on the same ac
mains circuit is switched on it produces a loud pop in the speakers. I have
also noticed that there is a loud pop when the amplifier is switched on as
well. How can I fix this?

I'm having a similar problem, but for now, I don't care about the "power on" pop. My setup is at the church I
go to and I'm not exactly sure if its the amp or the wireless microphones are at fault. The pops are very random
and I'm not sure what the cause really is. I've narrowed it down to these odd possibilities:
1) Some EMI noise source.
2) Static electricity.
3) A mechanical "noise" from the microphone holder.
4) A poor connection at the battery holder or power switch in the microphone.
5) Popcorn noise from the microphone.

 

[Don]

I'll try the 0.22uF cap but would you place it directly across the secondary
or after the bridge reg's?

 

[N. Thornton]

The *best* place to place snubbers is at the *source*... snub the
offending switch.

Well Jim, you know its my job to disagree with you Seriously tho,
these old amps will be vulnerable to numerous switches etc. You can't
snub the source because there isn't one, there's a house full of them.
The only practical solution is to give the amp some click-proofing
filtering.

Regards, NT

 

[N. Thornton]

I'll try the 0.22uF cap but would you place it directly across the secondary
or after the bridge reg's?

Maybe you'd best not take the cover off at all.

Regards, NT