[CJG888]

Do you know what your dealer will do yet?

Are you going to change the coupling caps? If so, to which brand are you likely to change them?

I am considering either Mundorf or Audio Note.

 

[jamescodway]

He's going to open it up and make a recommendation on new caps plus something to reduce/eliminate the mains hum.
 
His personal taste is grado. We debated the lack of affordable great amps in the UK for Grados... I think his ears are very different to mine as he has no time for any Sennheisers. In this context, I'll be taking the recommendations somewhat on trust!!
 
The main thing is the 50hz mains hum.
 
I'll keep you posted...
 
I wish the Psvanes were more readily available in UK/EU 

.
 
Best
 
James

 

[CJG888]

Please let me know the outcome!
 
I'm tempted to pick up some TOTL Mundorf caps on my next trip to Europe. Also, do you think there is room for a DACT stepped attenuator in there?

 

[jamescodway]

Hello there. Update on the work in progress...

"The main issues we’ve found are poor routing of some of the wiring, the mains input runs very close to the mains inlet, the high voltage supply is noisy and the heater supply is noisy.
 
We’ve made it almost completely silent by addressing some of the above, we are now taking things off systematically to see what is critical and what is not. The heater supply is absolutely a problem (we’re running it off a bench power supply and it’s much improved), we’ve tried an extra cap stage and it helped, but I will get some parts and see if we can add some extra (resistor & capacitor) stages to really reduce the noise without losing too much voltage. The wiring has been rerouted so that’s it’s further away from the mains connections, we’ve experimented with wiring the mains into the chassis further away from the rear panel but that was less of a benefit so that can hopefully remain as original (it would be a bit of a fiddle to do anything else to be honest).
 
In terms of upgrades there are a couple of signal caps i’d suggest changing, assuming they’d fit then using the Mundorf Silver/Oil type would be advisable and it’d be nice to change the input wiring to something like Audio Note AN-A. "

I'll keep you posted.

Best

James

 

[jamescodway]

I'm hoping to get the amp back in the next 5-10 days. I'll report full specifications and findings.
 
Best
 
James

 

[jamescodway]

I've had the amp back a couple of weeks now. The hum is reduced but not gone. It has made the amp somewhat more usable with quieter/classical music. The power supply has been beefed up and the RS-1s and k701s are a step up in performance as a result. New HD800s are excellent if not the best in terms of hum. The guys put in a lot of hours and testing but charged me very little. Overall the conclusion was that the box and power supply design is flawed from the p.o.v of hum. A long time to wait but a decent upgrade for the price (Deco Audio in Aylesbury).
 
Best
 
James

 

[tubeform]

Ive changed pentodes EL 84 with double triodes ECC 99 JJ and changed circuit, I changed 12AU7 wth 12AX7. Triode sound is the best. But the best was triode amp with 2A3 6 W for channel, made in  Czech Republik by JH sound.

 

[capitanharlock]

I recently took out the Cyber 20 from the box where it was, since I just bought a Grado Ps500e, and since I didn't remember any noise or hum.

I can say that I remembered correctly: at first I heard a strange low background noise (kind of cracks and pops) but I soon discovered that I had to tighten better the PSU cable (the connector isn't really perfect), and the noise disappeared.

My Cyber 20 is completely silent, at least using two Grados (Rs125 and Ps500e).
The Grados are relatively high efficiency headphones, so they should reveal any hum better than an high impedance one.

The output level with the Grados is very high and I can't use more than half of the volume knob excursion.

If it can helps, my Cyber 20 has still the original stock tubes, and it's been used only some hours.

Hope it helps.

 

[ddd777]

  Get the Psvanes! I'll repeat that, in case I didn't make myself clear. GET THE PSVANES!!!!
 

I just popped in to say a big "thank you" for your advice: Psvanes with consonance is really it. You nailed it perfectly! I match two psvanes with telefunken for the power and akg k340 connected at 'high' position output, and I couldnt be happier! It just oozes so much musicality, sweetness and brilliancy.. What a perfect little setup it is.
thank you, sir, for excellent match.