The Newton 300B

[Ray P]

Result!

I see you've even produced a user manual, tucked to the side of the nearest metronome!

[Cressy Snr]

Fab stuff Dave.

[Irene Idler]

I see you've even produced a user manual, tucked to the side of the nearest metronome!

Believe it or not, that's actually a bound set of every issue of the daily Los Angeles Tribune newspaper from February 1916. The front page of the first issue has the headline, "ZEPPELIN RAID OVER LONDON," underlined by a row of tiny swastika dingbats. Little did they know.

Tragically, before I got my hands on it, some bastard cut out the interview with Nikola Tesla, in which he predicted that in the future, war would be conducted by wireless. The guy really was prescient. There's still an ad for the interview, though, and it's pretty cool. Unfortunately, newsprint being what it is -- especially when idiots have tried to touch it up with sellotape -- the whole thing is in a right state and bits fall off every time I get it out, so I rarely do. It's fascinating to look through, though. It was such a different time!

[Thermionic Idler]

Nice write up and photo. Great news that you are really happy with them.

Ah, the open hearth fire on the TV screen. I’ve got that, complete with authentic crackle in my car

Nice!

Thanks Greg, these were inspired originally by hearing your WAD push-pull 300B at that Eggfest years ago - the way that amp communicated the music has stuck with me for years, and I eventually had to scratch that itch!

[Nick]

The guy really was prescient.

Is that an alternative spelling of "mad as a box of frogs"?

[Irene Idler]

The guy really was prescient.

Is that an alternative spelling of "mad as a box of frogs"?

Well, sure, that too, but I'm guessing you'd be a bit strange too if you could predict the future that accurately!

[Thermionic Idler]

Thanks for the kind comments everyone. Well, I had to do something during lockdown!

Oh and thanks to Ant for doing a cracking job with the wood chassis and transformer covers.

[Nick]

The guy really was prescient.

Is that an alternative spelling of "mad as a box of frogs"?

Well, sure, that too, but I'm guessing you'd be a bit strange too if you could predict the future that accurately!

Let me know when there is any actual prediction instead of vague hand waving.

[Irene Idler]

Is that an alternative spelling of "mad as a box of frogs"?

Well, sure, that too, but I'm guessing you'd be a bit strange too if you could predict the future that accurately!

Let me know when there is any actual prediction instead of vague hand waving.

Back in a bit. I have to go launch a DDoS attack.

[Nick]

Well, sure, that too, but I'm guessing you'd be a bit strange too if you could predict the future that accurately!

Let me know when there is any actual prediction instead of vague hand waving.

Back in a bit. I have to go launch a DDoS attack.

And you think that’s what he had in mind when he said "in which he predicted that in the future, war would be conducted by wireless"?

[Irene Idler]

Let me know when there is any actual prediction instead of vague hand waving.

Back in a bit. I have to go launch a DDoS attack.

And you think that’s what he had in mind when he said "in which he predicted that in the future, war would be conducted by wireless"?

Quite possibly. I'm pretty sure conducting war via his World Wireless System, which would transmit energy through the air wirelessly, is what he meant. If that's the case, it's looking more and more like we're already there.

But let's not clutter up Dave's nice amp thread arguing over the finer points of energy weapons, which I'm sure aren't what anyone is here for.

[Thermionic Idler]

Meanwhile, a question to the board - should I be addressing the over-voltage on the heaters or is this within tolerance? All heaters are AC.

EDIT... hmm, some research seems to suggest I can answer my own question - they're all sitting about 10% high give or take a bit, which is a fair bit outside the 7% that the Mullard engineers suggest should be the limit. I don't think that can be doing the sound any favours either.

Looks like some dropper resistors are called for...

[steve s]

Looks like some dropper resistors are called for...

I always check the incoming mains voltage, as the heater volts will vary with that, ie my house is usually around 245 volts but I can see well over 250 in the early hours, (I once measured 274 !) So make sure your heater voltage is set with attention to this.
Looks a great job..

[Thermionic Idler]

Looks like some dropper resistors are called for...

I always check the incoming mains voltage, as the heater volts will vary with that, ie my house is usually around 245 volts but I can see well over 250 in the early hours, (I once measured 274 !) So make sure your heater voltage is set with attention to this.
Looks a great job..

Thanks Steve, I just checked the voltage and we're at about 245 volts as well, no wonder the 300B heaters are too hot, the 5V transformer's primary is wired for 230V (I should have paid more attention to that). I have a variac so for the sake of the filaments I'm going to try running them on a reduced supply voltage for this evening's listening (assuming the supply was around 245 at the point of measurement then it needs to go down to 220 or so). Of course the B+ voltages will also all go down by 10% so it'll be interesting to hear the effect on the sound.

[steve s]

I've never found heater voltage to have much effect on the sound dave, but I've always been careful and not set them high,


If your ht is right, I would use a couple of large (probably) sub 1 ohm droppers.