"Uwe Surojegin" wrote:

Hello Folks,
I'm servicing an Acram Alpha 3 amplifier. The amp gives clear and nice sound
up to a volume of around 11 o'clock on the volume potentiometer. Above 12
o'clock the amplifier gives a "bad" distortion on both channels.
Has anyone an idea what that that could be?

The problem could be caused by oscillation. Have you checked the
amp with a o'scope?

Norbert

Hi again,
I have not checked the amp with a scope - I dont have one. But, in general
.... it could well be that the amp is going into clipping already. I'm not
very familiar with the Alpha 3 model. Maybe someone could give me input
about his experience(s) with the Alpha 3 model. Would appreciate it.
P.S. I'm running the amp into an 8 Ohm speaker system. So the impedance
could not be the reason.

Rgds
Uwe

"Norbert Hahn" schrieb im Newsbeitrag
...
"Uwe Surojegin" wrote:

Hello Folks,
I'm servicing an Acram Alpha 3 amplifier. The amp gives clear and nice
sound
up to a volume of around 11 o'clock on the volume potentiometer. Above 12
o'clock the amplifier gives a "bad" distortion on both channels.
Has anyone an idea what that that could be?

The problem could be caused by oscillation. Have you checked the
amp with a o'scope?

Norbert

Uwe,
You should be able to get specs at Arcam's website, www.arcam.co.uk.

Regards,
Tim Schwartz
Bristol Electronics


Uwe Surojegin wrote:

Hi again,
I have not checked the amp with a scope - I dont have one. But, in general
... it could well be that the amp is going into clipping already. I'm not
very familiar with the Alpha 3 model. Maybe someone could give me input
about his experience(s) with the Alpha 3 model. Would appreciate it.
P.S. I'm running the amp into an 8 Ohm speaker system. So the impedance
could not be the reason.

Rgds
Uwe

"Norbert Hahn" schrieb im Newsbeitrag
...
"Uwe Surojegin" wrote:

Hello Folks,
I'm servicing an Acram Alpha 3 amplifier. The amp gives clear and nice
sound
up to a volume of around 11 o'clock on the volume potentiometer. Above 12
o'clock the amplifier gives a "bad" distortion on both channels.
Has anyone an idea what that that could be?

The problem could be caused by oscillation. Have you checked the
amp with a o'scope?

Norbert

Hi there Uwe,

The amplifier's volume control feeds the power amps directly if you
use the direct switch. At full volume setting it will only take about
300 millivolts to clip the amplifier, so it looks to me like your
source voltage is higher than that (a CD player perhaps, which can
deliver 2 volts at full output?). So my best guess is that Tim is
correct and there is nothing wrong with the amplifier. Send me your
fax number and I'll have someone fax over the circuit if you are still
stuck.

John Dawson (Arcam)

Tim Schwartz wrote in message ...
Uwe,
You should be able to get specs at Arcam's website, www.arcam.co.uk.

Regards,
Tim Schwartz
Bristol Electronics


Uwe Surojegin wrote:

Hi again,
I have not checked the amp with a scope - I dont have one. But, in general
... it could well be that the amp is going into clipping already. I'm not
very familiar with the Alpha 3 model. Maybe someone could give me input
about his experience(s) with the Alpha 3 model. Would appreciate it.
P.S. I'm running the amp into an 8 Ohm speaker system. So the impedance
could not be the reason.

Rgds
Uwe

"Norbert Hahn" schrieb im Newsbeitrag
...
"Uwe Surojegin" wrote:

Hello Folks,
I'm servicing an Acram Alpha 3 amplifier. The amp gives clear and nice
sound
up to a volume of around 11 o'clock on the volume potentiometer. Above 12
o'clock the amplifier gives a "bad" distortion on both channels.
Has anyone an idea what that that could be?

The problem could be caused by oscillation. Have you checked the
amp with a o'scope?

Norbert

Hi there John,
first of all: Many thanks for all the input and help. Second: My fax number
is: +49-7541-26060
I checked my CD player output: Very low voltage, not nearly close to 300 mV.
Of course, I had to replace the volume poti (was broken, originally I guess
20K Ohm) and replaced it with a 50K Ohm Alps potentiometer. So this could
certainly not be the case. Other parts have been checked already ... but
still not really satisfied. Other high-end freaks which are familiar with
this unit tell me that the clipping would be tolerated around 2 o'clock -
but not before. So, I'm still trying to double-check my circuit etc and the
AC - DC sources, diodes and capacitors. I'll keep you posted.

Uwe

"John Dawson" schrieb im Newsbeitrag
om...
Hi there Uwe,

The amplifier's volume control feeds the power amps directly if you
use the direct switch. At full volume setting it will only take about
300 millivolts to clip the amplifier, so it looks to me like your
source voltage is higher than that (a CD player perhaps, which can
deliver 2 volts at full output?). So my best guess is that Tim is
correct and there is nothing wrong with the amplifier. Send me your
fax number and I'll have someone fax over the circuit if you are still
stuck.

John Dawson (Arcam)

Tim Schwartz wrote in message
...
Uwe,
You should be able to get specs at Arcam's website, www.arcam.co.uk.

Regards,
Tim Schwartz
Bristol Electronics


Uwe Surojegin wrote:

Hi again,
I have not checked the amp with a scope - I dont have one. But, in
general
... it could well be that the amp is going into clipping already. I'm
not
very familiar with the Alpha 3 model. Maybe someone could give me
input
about his experience(s) with the Alpha 3 model. Would appreciate it.
P.S. I'm running the amp into an 8 Ohm speaker system. So the
impedance
could not be the reason.

Rgds
Uwe

"Norbert Hahn" schrieb im Newsbeitrag
...
"Uwe Surojegin" wrote:

Hello Folks,
I'm servicing an Acram Alpha 3 amplifier. The amp gives clear and
nice
sound
up to a volume of around 11 o'clock on the volume potentiometer.
Above 12
o'clock the amplifier gives a "bad" distortion on both channels.
Has anyone an idea what that that could be?

The problem could be caused by oscillation. Have you checked the
amp with a o'scope?

Norbert

"Uwe Surojegin" wrote:

I checked my CD player output: Very low voltage, not nearly close to 300 mV.

Only a very few CD players have such low output voltage, unless they
have a volume control.

Of course, I had to replace the volume poti (was broken, originally I guess
20K Ohm) and replaced it with a 50K Ohm Alps potentiometer. So this could
certainly not be the case.

The volume control of my amp is located in the feed back loop, thus
its value is important. Replacing a 20 kOhm potentiometer with a
50 kOhm type would influence stability.

But I don't know your amp so it can be a different problem. OTOH you may
simple connect a resistor in parallel to the volume pot (47 kOhm are a
good start) and check if the distortion/oscillations are gone.

HTH
Norbert