[ColSaulTigh]

Looks like he has the older version 1956 and older with solid plates. Made for russian marine if there is a round stamp on the glass.

Did you hear a "1578" and 6h8s to be different?

I have, and yes, I hear a difference. 6H8S are not as clear and crisp, and (IMO) not as impactful with bass and sub-bass. More akin to a "6SN7" sound, whereas true 1578's are extended on both ends, more weighty, and more open and airy. Similar to how a 6F8G sounds, but not as wet and slick. Again, IMO, YMMV.

 

[Salmonad]

I have recently installed quad KT88 on my Euforia AE. I am hearing a hum that I never heard before using my ZMF Vérité Closed. Is this normal or is there a ”trick” I’m missing.
It has nothing to do with my chain since the hum is there even when not connected to anything. The tubes have been burned in for at least 100 hours.

Any tips?

 

[ThanatosVI]

I have recently installed quad KT88 on my Euforia AE. I am hearing a hum that I never heard before using my ZMF Vérité Closed. Is this normal or is there a ”trick” I’m missing.
It has nothing to do with my chain since the hum is there even when not connected to anything. The tubes have been burned in for at least 100 hours.

Any tips?

Clean the pins of both tubes and adapters and try again

 

[barontan2418]

I have recently installed quad KT88 on my Euforia AE. I am hearing a hum that I never heard before using my ZMF Vérité Closed. Is this normal or is there a ”trick” I’m missing.
It has nothing to do with my chain since the hum is there even when not connected to anything. The tubes have been burned in for at least 100 hours.

Any tips?

Possibly a faulty adapter. Doubt you have a spare so you could try using two different driver tubes without adapters then change all power adapters so as to test all four. It is not unheard of for KT88/KT66 to have a slight hum which is usually lost when music plays. Good luck. I run EL11'S into two KT88's which is totally silent.

 

[Salmonad]

Possibly a faulty adapter. Doubt you have a spare so you could try using two different driver tubes without adapters then change all power adapters so as to test all four. It is not unheard of for KT88/KT66 to have a slight hum which is usually lost when music plays. Good luck. I run EL11'S into two KT88's which is totally silent.

Thanks for the advice guys. I’ll try these things tomorrow.

 

[Salmonad]

Unfortunately I still have this zero volume hum no matter what tubes I put in. I cleaned the pins. Is there any more advice? Is there a specific way to clean the pins?
I don’t have anything but my zmf vc connected to the Euforia. It is not the headphones because I tried connecting these directly to my dac with on-board amp and there was no problem. I also tried connecting my Euforia to my dedicated electricity circuit that I use for my Hifi and I still had the hum.
I can’t talk about a black background as some do….no matter what tubes I put in.
I’m starting to question myself whether I am being too picky and maybe this is normal.

 

[incredulousity]

It’s your power. Try iFi DC Blocker and GND blockers. Or get a Furman at the least, or better still a Puritan PSM156. But they cost as much as your amp.

ZMF Verité of either type is about as sensitive a headphone to noise as you will find, short of IEMs.

 

[Salmonad]

It’s your power. Try iFi DC Blocker and GND blockers. Or get a Furman at the least, or better still a Puritan PSM156. But they cost as much as your amp.

ZMF Verité of either type is about as sensitive a headphone to noise as you will find, short of IEMs.

Why do I not hear this on any other equipment? Is the Euforia the least forgiving?

 

[incredulousity]

Why do I not hear this on any other equipment? Is the Euforia the least forgiving?

It’s actually much more likely a power problem than an amp problem. Tube amps are more sensitive. You might have bad tubes, but I think you said that it was regardless of tubes used. Does it make the noise with no input cables connected? Are your power cords and interconnects shielded, and separated?

 

[Salmonad]

It’s actually much more likely a power problem than an amp problem. Tube amps are more sensitive. You might have bad tubes, but I think you said that it was regardless of tubes used. Does it make the noise with no input cables connected? Are your power cords and interconnects shielded, and separated?

Power cords are fine….tried different ones at different locations in the house. I have a separate power line down to my music studio but even on this circuit it had a hum.
Interconnects weren’t even connected.

 

[incredulousity]

Could be the weird case of a bad transformer in the amp, or major EMI/RFI interference, though it seems you would have noticed difference moving amp around.

 

[Salmonad]

Could be the weird case of a bad transformer in the amp, or major EMI/RFI interference, though it seems you would have noticed difference moving amp around.

I’ll reach out to my local Hifi dealer and see what I can try. Thanks for your support.

 

[incredulousity]

Could be a whole house power issue too. What are you using for power conditioner now?

 

[Deleeh]

One thing must also be mentioned.
According to Feliks, putting 4 KT88 tubes on the Euforia is not intended.

Feliks recommends using the tubes listed in the manual.

Of course it is possible to use 4 Kt's, but I think that was the weakness of the Euforia if I remember the old reports correctly.
This is also due to the fact that they are quite close to the upper limit in terms of amperage.

I would be careful with the hi-fi dealer, if he knows that you are doing things that are not in the manual, he can refuse to repair them.
Even an exchange if you are still in it.

Take out two KT tubes and replace them with a couple of 6SN7 and see if it improves.

What you should also keep in mind in the future is that a set of 4 is also matched.
It can be that 1-2 tubes put too much strain on the bias control.
Usually one tube is enough and the drama is perfect.

You can check if one of the tubes hums when there are two 6SN7 in the front.
Plug in two Kt 88 and leave them in for 30 minutes, then switch them off, wait a bit and put in the next pair.
If only one channel is humming, mark the tube.

By the way, I also use adapted 6V6 tubes,
They also hum a little but not so much that it interferes with the music.
Of course you shouldn't do it but some 6V6 are better than 6SN7.

 

[Salmonad]

No conditioner but a Dynavox X4100 Power Filter connected to my Euforia.
Up until now I have only had my hifi stuff in the studio where I've never had problems. Now I'm listening in the bedroom but as I said, the problem is also with the amp when I take it into the studio.
I have been a bit reluctant to buy an expensive power conditioner for a 3000 Euro headphone amp. I don't think my DAC (Mola Mola Tambaqui) would benefit from a power conditioner.