[KPzypher]

The low hum is from both sides or single side?

Have you tried other tubes?

Yep both sides. And I've tried numerous tubes.

 

[KPzypher]

Sorry to change the subject from the noise issue, I'm sure it's frustrating, but I was wondering if anyone has had some experience with trying out tube types that are not specifically mentioned in the specs. In this thread we talked already about the 5755, which I wouldn't know or trust without knowing the recommendation came from the amp designer himself (and it's one of my faves!). I've since been reading about other tubes that could be compatible, but not having much experience with tube amps, I'm unsure of what could happen. Specifically, has anyone tried a pair of 6094 (apparently EL84-ish, but needs an adapter) or a 12BH7? Is there a way to tell if they are compatible, and how much damage can I do if I plug in a tube that the amp doesn't like?
[/Qtunes.

Yeah the 5755, Justin told me over the phone that was his favorite for the Pendant. I trust his judgment as the designer/maker. And sorry, don't have any experience with the other types you mentioned.

 

[attmci]

Some other suggestions:

Try the amp in your neighbors house to see if it's the ground loop hum (dirty power).

Fasten all the screws on the transformers.

Use a transformer cage like this:
https://www.radfordrevival.co.uk/spares-services/transformer-cages/

 

[zach915m]

Some other suggestions:

Try the amp in your neighbors house to see if it's the ground loop hum (dirty power).

Fasten all the screws on the transformers.

Use a transformer cage like this:
https://www.radfordrevival.co.uk/spares-services/transformer-cages/

These are good suggestions!

I wish I had more answers for specific noise issues with tube amps. Having gone to audio shows all over the world for ZMF - it's always been one thing or the other with tube amps and solving noise issues on the fly, and it's never the same amp or noise that I run into having to solve. There have been times where I will just pull an amp from our table at shows if I can't get it quiet enough.

One thing I've learned to do is bring two or three sets of tubes per amp to different locations because certain tube types and makes will pick up noise from one source over the other. Sometimes certain gear doesn't like being close to one another and then there's a plethora of other things I know we've talked about here as well.

I am lucky that in our shop and my home my amps are dead quiet when I have good tubes in them.

I know one thing I spoke to @ampsandsound about once is that different areas and locations can have voltage that is off of the needed voltage for the transformer. So even though the amp is set for 110v, and the USA is almost always hypothetically 110V, you might get an area, house, etc etc that is coming out at 100v or maybe even 120v or anywhere in between. Go too far off what the transformer is rated at, and you'll have a consistent ground hum. I've experienced this first hand many times, and sometimes in the UK even. I think the only fix is to get a noise isolator with it's own transformer in it that regulated the power back to 110v. Maybe @ampsandsound can chime in and let me know if what I'm saying makes sense or not to the conversation we had? Could this be what these Pendant users are running in to? Is there a surge protector or device you can use to check this and regulate it? Multimeter maybe?

 

[Polygonhell]

The standard voltage in the US is 120V, but the most common input voltage for power transformers seems to be 115V.
One thing I have not tried is shielding the power transformer, I think I have some magnetic shielding film somewhere.
I captured my mains voltage with a scope recently, I can post it if it’s actually useful, it’s far from ideal, but It’s 120V RMS, with no ground offset.
Obviously the best test would be to try the amp in a different location, but with the current situation, it’s not very practical.

back on the tube rolling topic, I didn’t really have a strong preference for any of the rectifier I tried, the old Mullard 12AU7 was my favorite, and I ended up using Tungsram EL84’s.

 

[ScornDefeat]

How hot do your EL84s/power output tubes get in your Pendants?

My input tube only gets mildly hot...but my powe output tubes get scorching. Probably hotter than any other tube gear I've had.

 

[KPzypher]

How hot do your EL84s/power output tubes get in your Pendants?

My input tube only gets mildly hot...but my powe output tubes get scorching. Probably hotter than any other tube gear I've had.

I got burned once touching those, so I'm guessing that's normal. The rectifier tube gets pretty hot too.

 

[ScornDefeat]

I got burned once touching those, so I'm guessing that's normal. The rectifier tube gets pretty hot too.

Very true, rectifier gets very hot, the output tubes get outright scorching. A very quick tap and I got burnt, they are no joke! Good to know it's not just mine haha

 

[Polygonhell]

Use a transformer cage like this:

FWIW I just tried wrapping the mains transformer in the magnetic shielding film I had on hand and no impact, Noise floor is exactly the same with or without it.

 

[ampsandsound]

Hey Folks. Few tid bits... All tubes get to enough to burn off your finger prints... completely normal and why I dont have sensation in 2 fingers.
All of our power transformers are spec'd as 120V or 230V accordingly and all include shields.
There are alot of factors that influence noise floor for which Zach listed the many.
System matching is super important with any tube amp with the Pendant included.
The Pendant was conceived as a dual purpose amp, quiet enough for high efficiency headphones and powerful enough for planers.
Using the low z will likely provide the lowest noise floor and most base grip whereas the High Z will give a lighter/more dynamic sound.
If noise is a principal concern, the low z is the very best chose.

One last thing.... I love JJ ECC99s on the Pendant... I also enjoy Japanese Mullard 12AU7s.

 

[steve468]

Hey Folks. Few tid bits... All tubes get to enough to burn off your finger prints... completely normal and why I dont have sensation in 2 fingers.
All of our power transformers are spec'd as 120V or 230V accordingly and all include shields.
There are alot of factors that influence noise floor for which Zach listed the many.
System matching is super important with any tube amp with the Pendant included.
The Pendant was conceived as a dual purpose amp, quiet enough for high efficiency headphones and powerful enough for planers.
Using the low z will likely provide the lowest noise floor and most base grip whereas the High Z will give a lighter/more dynamic sound.
If noise is a principal concern, the low z is the very best chose.

One last thing.... I love JJ ECC99s on the Pendant... I also enjoy Japanese Mullard 12AU7s.

Do you use the JJ ECC99 in place of EL84s? I’m not familiar with that tube, and online descriptions make it sound like it can be used anywhere depending on the application. Thanks for the input!

 

[ScornDefeat]

Do you use the JJ ECC99 in place of EL84s? I’m not familiar with that tube, and online descriptions make it sound like it can be used anywhere depending on the application. Thanks for the input!

The JJ ECC99 is a preamp tube, it would replace the 12AX7/ECC83.

 

[KPzypher]

Hey Folks. Few tid bits... All tubes get to enough to burn off your finger prints... completely normal and why I dont have sensation in 2 fingers.
All of our power transformers are spec'd as 120V or 230V accordingly and all include shields.
There are alot of factors that influence noise floor for which Zach listed the many.
System matching is super important with any tube amp with the Pendant included.
The Pendant was conceived as a dual purpose amp, quiet enough for high efficiency headphones and powerful enough for planers.
Using the low z will likely provide the lowest noise floor and most base grip whereas the High Z will give a lighter/more dynamic sound.
If noise is a principal concern, the low z is the very best chose.

One last thing.... I love JJ ECC99s on the Pendant... I also enjoy Japanese Mullard 12AU7s.

Thanks Justin for you input.

I thought 12BH7/ECC99s draw quite a bit more current? Is it safe to use on a Pendant??

What other input tubes are compatible w/ the Pendant besides the 12xx7 series?

Thanks again.

 

[ampsandsound]

We have tried without issue but can’t recommend formally yet. Need to do a bit more testing. The Mullard 12au7 that was made in Japan is remarkable as well.

 

[KPzypher]

We have tried without issue but can’t recommend formally yet. Need to do a bit more testing. The Mullard 12au7 that was made in Japan is remarkable as well.

Do let us know. I just ordered one after your last message lol