high pitched beep tone in Eros

[Jeroen]

After having worked excellent for a couple of years lately my Eros phono amp sometimes produces a beep tone in one channel. Most of the time it's the same tone, sometimes the beep lowers an octave. It's there half of the time and not very loud, but very annoying.

I told an audio friend about this problem, he suggested that the powersupply is oscilating.

Does anyone could help me solve this problem?

Thanks in advance!

Best Regards,

Jeroen

[Doc B.]

Sounds like a cell phone is transmitting.

[Jeroen]

Hi Doc,

Thanks for your input. Could be a cellphone, but the thing is, the beep problem started a couple of months ago while we have cellphone's for a  couple of years here in Holland.

Last month a dedicaded audio group was installed in our appartemt. Since then the volume of the beep lowered a bit, but the beep still is there..

[Paul Joppa]

Are the beeps always the same length of time?  Are they a consistent level, or do they fade in and out? Do they occur at random or regular time intervals? Can you guess the audio frequency? These questions are aimed at indicating whether it's an internal or external source.

Does it happen with the input cables removed? You may need to insert shorting plugs to really determine this, but worth it to try without

Being in one channel suggests it may be a tube, or a connection. You can swap the EF86's to see if it follows the tube. If you have a spare 12BH7 and/or 6922, swapping them in (one at a time) that might reveal something.

[Natural Sound]

Is it safe to assume that the tube shields are in place?

[Jeroen]

The Beep tone is constant during 15 minutes or so.  I guess the frequentie is around 5000 Hz. I swapped the EF86 tubes, but the tone remains in the left channel.

I will try to remove the input cables and shorten the input. And will search for a spare 12 BH7 tube.

Tube shields are present.

[Jeroen]

Problem solved!

It was the E88cc tube (Tesla)  causing the beep tone.  I replaced it bij a JJ balanced tube. Great improvement in soundstage, much deeper and wider,  and far more open sound. I can recommend this tube warmly!

Regards,

Jeroen