Has anyone heard an all valve rig e.g. Axis, S&P?

valve head777 wrote: Mmmm, does a TX core really change its magnetic properties? Generally, it's the output tx that dictates the sound before saturation occurs I believe. Overdriving valves does wear out the screen and output impedance is also crucial to this. The thing I like is the wave shape becoming a sort of saw tooth. I do know a builder who winds his tx's so they reproduce a square wave up to 40khz. His hifi amps do sound good. Unfortunately he's been brainwashed by the alt-right, but that's another story!! Maybe succumbed to too much RF radiation from his pirate radio transmitter heh heh..... Yes, the physical weight is horrible, but when people see the blue pulse in time with the b-line, they're sort of memorized! And they do seem to love it when the bass begins to fry.

Magnetics certainly can decay with time, some worse than others. Depends a lot on how the material is constructed I expect. Also laminations can come loose over time and start buzzing etc. For sure the output Tx has an influence on the sound but imho the key to it all is the interplay between the output valves and the Tx together in terms of setting a load line. Plus of course anything you design the pre-amplification driver stages to achieve.

Indeed setting the primary impedance is very important when it comes to your valve plates melting or not! And that is also affected by the load you put on the transformer secondary. In the opposite direction to solid state a valve amp is more likely to go pop if you put a higher impedance on the output Tx secondary.

A sawtooth wave is a combination of odd harmonics, so would be linked with a push pull output stage that tends to cancel the evens. Pentodes also tend more towards odd harmonics as I recall, can't quite remember why off my head though.

A well reproduced square wave up to 40KHz is quite respectable bandwidth, wonder what the lower limit of such an output Tx is.

More of a guitar amp person these days, but maybe in the future I'll have a go at some dual channel stuff. Spending a lot of time currently looking into variable power reduction circuits for guitar amps.

Roman wrote: I am putting together a vintage style rig. Looking at valve amps as an option. How do Valve a tron and Sound and Pressure sound compared to their solid state counterparts? We had a dance here using a valve amp on 4 scoops. I didn't hear enough of a difference to be convinced valve amps are necessary. Some people seem to be religious about the valve sound. Have you been to a Valve a torn or Sounds and Pressure dance? How was the sound? Valve amps are not the only factor though.

Out of interest, what valve amps did you use, and what scoop/driver combination?

I'm not 100% sure tbh, if you read Morgan Jones he most definitely ascribes to the deterioration of older magnetics such as chokes and transformers. I don't have enough real life experience to be totally confident in it. But entropy gets all things eventually so it would not surprise me if magnetic dipoles could reorder over time, perhaps due to the microstructure of the steel changing. I am thinking many decades here as opposed to a few years.

Pentodes probably do get harsher quicker when overdriven but as always the devil is in the details of how the particular circuit was made and what being overdriven means. Triodes are less noisy in general and usually the choice for HiFi as a result. Pentodes certainly dominate the world of higher power guitar but I couldn't say if its for tone or an easy power boost. Probably the 2 are inter related as always!

i remember a valve system are leeds area in the late 70s. they used ex-bbc valve amps, they could of been modified valve transmitter amps? used to cover 3000+ people

I've got a mental image of a chap face who winds reasonably sized 50-100W sized output Txs being presented with a picture and spec of the desired 20kg beast If the funds are there it'd be a neat challenge anyway.

I wonder if there is a market for 500W-ish channel PA amplifiers still. Bit of a lost art but no reason it couldn't be revived a little if the customers are there. Tube production doesn't look like it is ceasing anytime soon. Even transmitter tubes are still being produced for applications that demand them. Typically 7-10kV regulation is required for thin film evaporation processes for a start and that is a huge market which produces the compound semiconductors behind the wireless RF comms boom.

Hope this hasn't  gone too off topic for the OP......

16 drivers, 4 cabs fed with 500w of valve power each would be a system to behold. Drop John Holts 'Ali Baba' on Treasure Isle....... Bring a smile to my face!!!