Hiss/noise

[Kmmm]

Hi
I've had a Eros for about 4 years now. Love it! But I've always been troubled with noise/hiss. I have 106db speakers. I just noticed that I have LM431 labeled "WS" should I try changing them?
I have to mention that I have tried replacing the tubes with 3 different sets, in several combinations – with no improvements... The amp is a Steremour (I)
with no hiss when the Eros is disconnected. https://bottlehead.com/smf/index.php?topic=5828.30

I have Another question as well (this might belong some where else..) : I'd like to implement a MiniDSP to my system Running my AER BD3 from the Steremour and the bass units from two Hypex UcD400HG
The stereomour using AC filaments does give me a hum. Not much but audible. If i put a HP filter on the stereomour running the full tones from say arround 200-250Hz i will still get the hum Right?
But if I put a cap in parallel on my element, say 50uf, would this block out the hum? I might be raving here...I'm new to this...

Greatfull for any help on this.

[Paul Birkeland]

Yes, I would try replacing the WS431s.

[Kmmm]

Thanks! I'll try that :-)

[2wo]

As for the hum. It is probably the residual from the AC on the 2A3 filament. Useing a filter on the input of the amp won't' help if that is the case, you can test this using shorting plugs on the inputs.

On the other hand if you are not using the amp to drive the woofer, the hum might be less noteasable. If it is, you can look into the D.C. Heater option....John

[Doc B.]

Also rewire the amp for the lowest output impedance. That will help to improve the S/N ratio.

[Kmmm]

Thank you for your input. Is there a DC heater option for the original Stereomur? I have been looking for that but not been able to find any. That would solve the problem.
As for the output impedance my full tones are 16 Ohm. It would still be OK to wire them for the lowest impedance?

[fullheadofnothing]

DC upgrade is for Stereomour II.

[Paul Joppa]

To fill in a bit, the lack of a DC heater supply was one of the reasons for the Stereomour II design revision. It's a little tricky to make a DC supply for the low-voltage, high-current 2A3 filaments - we had to make a new power transformer to get there.

I don't know how to do it, but this is a little off-topic for the Eros thread. If it needs to go much further, perhaps a new thread should be started in the relevant forum.

[Kmmm]

Yes, Paul, Sorry

I'll start another thread. Thanks!

[Paul Birkeland]

As for the output impedance my full tones are 16 Ohm. It would still be OK to wire them for the lowest impedance?

Yes.  Driving a 16 Ohm speaker on the 4 Ohm setting provides a lower noise floor, better damping (bass control), reduced distortion, and reduced power.  All but one of these characteristics is desirable.