You are talking about audio enthusiasts, not audiophools, here. Audiophools are the people who will spend a fortune on a bit of cable with 'magic' properties, then connect it to an SET amp and fed it from vinyl. They are also the people who will discuss at length, in a wine reviewers prose style, the difference in sound quality one gets by changing the brand of thermionic rectifier in one's valve amp.
David.
Or engrave 11's on the front...
In message , Mark Kent writes
If you retrace the thread back a couple of days, you'll find the mains cables costing £2000 etc ...
LOL...there's also cash to be made from carefully emulating that distortion in software. I run a Strat through a PC running guitar amp simulation software and then through a "transparent" SS amp and speakers. Have a choice of several (virtual) vintage Marshall amp/speaker combos plus many others, all just a few mouse clicks away.
It is horses for courses. An electric guitar played through a flat distortion/noise free amp sounds....er...flat and thin. It is a common studio technique to record from mics strategically placed around the speaker of a "tube amplifier" to get that electric guitar sound.
I mentioned those back near the start of the thread, and was probably responsible for most of the subsequent discussion!
MANY year ago? They still are - they're just much more expensive now!
Afraid I'm not clear what point you were trying to make above.
The reality AIUI is that the fields from the heater can affect the field and potential levels at the cathode, and thus affect its potential and emission. Ergo, hum can be produced from the 50Hz on the heater of the cathode. To what extent this will happen will depend on the details of the valve and design.
Saying the 'cathodes eject the electrons' is only one part of the story. The *device* also uses a heater and an anode - and grids if it is more than a diode. And the various potentials, etc, all can affect what then happens. Including those on the heater wrt the cathode, etc.
So the heater can inject hum, even you the collect it from somewhere else like the anode.
Slainte,
Jim
"Mark Kent" wrote
Not so. If that were true why did so many pro-audio designs from the 1930s to the 1960s use d.c. to feed the heaters of the early stages? The EF86 had a special heater design to minimise hum, even so it was necessary to use d.c. supplies to entirely eliminate hum in EF86s in low signal stages.
Valve rectifiers would be unsuitable to rectify heater supplies as they have too high a forward resistance. Selenium, or later silicon, rectifiers were used for this purpose.
David.
....... IS the right answer!
It is not just the heaters of course. You have to get the power to the heater via wiring which may lead close to the grid. In most cases this won't matter a fig, but in the case of a microphone pre-amp, you are starting with an input signal of nominally -50dBu. If you are looking for a signal to noise ratio of at least 60 dB, then a VERY small signal will appear within this margin. An interesting and mainly historic problem of course, since these days one would use a low-noise Op. amp fed in any case, from stabilised supplies.
Les.
An electric guitar "sounds" nothing like a guitar.
Would be interesting to hear the likes of Clapton/Hendrix through a "transparent" system.
I know. That is what I use as an amateur guitar player. But some prefer a more "authentic" sound from the real thing.
Agreed.
Actually, an electric guitar played through a flat distortion/noise free amp sounds a lot like a very smooth warm guitar.
However, if you want an "extra crispy" guitar, then adding linear and nonlinear distortion may be on your agenda.
There are a number of ways to add linear and nonlinear distortion to an electric guitar:
(1) A non-hi fi amplifier that adds linear and nonlinear distortion via tone controls and nonlinear amplification stages, as well as the built-in speaker with non-flat, non-linear response.
(2) Starting in the 60s and 70s, musicans started adding "stomp boxes", which are foot-activated, special-purpose linear and nonlinear distortion generators that work in the analog domain.
(3) Starting in the 80s and 90s, musicans started using multi-purpose "amp simulators" which are essentially digital devices that generate the same-old, same-old linear and nonlinear distortion.
(4) All of the above.
The classic approach to that would be a SM-57 or SM-58 close-micing the speaker of a guitar amp.
If you're really good with a parametric equalizer, you can simulate a lot of the linear distortion of a guitar amp, particularly with a digital mixing console. I've got my "special sauce" for the 02R96 that I apply to the electronic instrument and electric guitar inputs. Also use other flavors of it for voices and acoustic instruments.
I suspect that is what I tend to get. But is hard to be certain for source material that is 'studio built'.
Slainte,
Jim
Perhaps it is down to expectations of what a particular genre should sound like. Never mind, I'll defer to your experience on this.
Yes, to achieve a certain required sound, crunchy, fuzzy or whatever. Not necessarily to disguise poor playing technique.
Yes, I use (3) myself, occasionally (1)
And sometimes even a mike at the rear of an open cabinet.
I'm just a hobbyist/dabbler with a PC based "home studio" and not a recording expert. For guitar I use prewritten DSP based amp simulator plugins with specified amp/speaker simulations as my starting points and tweak from there.
Fascinating and interesting post. Thanks.
Agreed.
Agreed.
And, the tube socket wiring to the filaments carries at least 6 vac which is about +16 dBV compared to -50 dBV or less from the signal source.
The usual end run on the induced voltage problem was to float the filament wiring, and then have a pot to balance the two lines with respect to ground. In practice, you needed two filament windings and two pots (1 per channel) as the optimal setting for one channel was never the same as the optimal setting for the other.
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