Nobsound 300b Monoblocks - HELP NEEDED!

[Wakefield Turntables]

When you say they should have worked from the beginning, you did start off by plugging in a source and pre and playing some music didn't you? As you only mention running then with no input and you can't judge a valve amp that way as it's not designed to be used with no input.

Yes, of course, I don't make a habit of just plugging a single monoblock into a speaker and listening to it all night.

[Lawrence001]

Ok it's just the only two statements referring to hum are these:

"The amps exhibit no hum from the Tx when fired up but as hum like a complete bugger when you attach them to a passive speaker, this is with no pre-amp connected."

"just attached the speaker cable from the speaker to the amp. No other cables. I've just tried powering up from the wall socket and still same old hum"

Personally I'd expect them to hum a bit connected as you describe, from my own experience with valve amps. At no point do you refer to any hum when they are connected into the full system and playing music. So I'm just asking if they also hum in that situation?

[rcarruthers]

https://www.ebay.co.uk/itm/284646515...EAAOSwhMFh-TCk

"Note: This 300B tube amplifier is second-hand, and there is some noise because the tube filament voltage is not adjusted well, we will send you a potentiometer to solve this problem.”

I was hoping to try these out with my ESL 57s & see if they had enough power to handle the impedance swings. SETs are usually not recommended for electrostats, but someone tried 300Bs & said they worked great.

They are affordable & good looking, so prob too good to be true!

[Lawrence001]

Is it really wise to bung in a potentiometer to the average punter to solve a heater filament voltage issue??

Sent from my BKL-L09 using Tapatalk

[Firebottle]

I think they are suggesting fitment of a hum-bucking potentiometer, it may reduce the hum, it may not.

I don't think the heater voltage is the issue.

[Lawrence001]

Either way I'm not sure eBay would approve of them saying this in the description "we will send you a potentiometer to solve this problem.”

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[guy]

Strange that if it would be easy for potential purchaser to fix that the seller doesn't just do it before listing

[rcarruthers]

Strange that if it would be easy for potential purchaser to fix that the seller doesn't just do it before listing

That was my question to Douk. No reply yet.

[Wakefield Turntables]

You'll not get one either!