This. Also they produce distortion.They don't hold their value when they heat up, or when they get old. Noisier than modern types. Expensive
Let's get this straight:
Carbon comp = bad
Carbon film = good
Metal film = more good
Carbon comp = bad
Carbon film = good
Metal film = more good
I meant for 6922 tube in a preamp gain stage
Is this the project? Do you have a schematic or is it a finished preamp?
Please note that power capability is just one aspect to chose an appropriate resistor. Voltage capability is another one. So a 1 W plate resistor is recommendable in certain cases.Power tube cathode resistors work hard, everything else can be 1/2w.
I doubt on that. My theory is: No one knows how a vintage guitar amplifier sounded when it fell from the manufacturer's production line. But all guitarists know how they sound nowadays. As you said:Carbon Comp resistors add something to the sauce in a Guitar amp.
Yes! I bet that the respective then new amp didn' sound any different form a today's new one. Their nowaday's sound is just an acquired taste due to the aged components.They don't hold their value when they heat up, or when they get old.
I prefer metal film resistors, where possible, as they're as cheap as carbon films now. Otherwise WW's. Carbon comp is an outdated and unreliable technology.
Best regards!
I decided to use plate choke.Is this the project? Do you have a schematic or is it a finished preamp?
What about NI wirewound resistor for cathode resistor?Let's get this straight:
Carbon comp = bad
Carbon film = good
Metal film = more good
Carbon comp = bad
Carbon film = good
Metal film = more good
Wirewound = really good
Carbon film = good
Metal film = more good
Wirewound = really good
I'm often a contrarian here on DIYAudio, I find many posts long on opinion but short on facts.
For example, the CC R;s are noisey, In 1957 I built this preamp for a General Electric Variable Reluctance Phono
pickup, mV's of signal. Its still here on the shelf but not run for years, Need another for stereo.
While in use it was very quiet.
Next amp your build that needs only a 2 Volt signal has a problem, it may be the
century olde tube making the noise in the cct.
For example, the CC R;s are noisey, In 1957 I built this preamp for a General Electric Variable Reluctance Phono
pickup, mV's of signal. Its still here on the shelf but not run for years, Need another for stereo.
While in use it was very quiet.
Next amp your build that needs only a 2 Volt signal has a problem, it may be the
century olde tube making the noise in the cct.
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I considered to build either 6922 or 6GK5 linestage.Is this the project? Do you have a schematic or is it a finished preamp?
I want to use plate choke to replace the 13.7K, and lower the B+ for lower drop as the plate choke is around 400-500R
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Technology marches on. Would use 1959's tech motor oil in a new car?
Will destroy the new car engine in short order...........
CC resistors wont destroy the amp but will make it noisier
Will destroy the new car engine in short order...........
CC resistors wont destroy the amp but will make it noisier
Carbon film resistors also don't survive short overload conditions, which they might see in a guitar amp setting.
Seen many posts here from the experienced 'smart set' which indicate Comp resistors are the lowest noise. So I've always used them in grid bias/ coupling/ stopper apps. Sure they tend to drift over time, usually higher in value, so might require annual check. Carbon film are used in all other places except PS circuits, which metal film gets the nod- those things are tough
Jim
Jim
Nope. Comp resistors are the highest noise. Carbon film is better, metal film is better and wire-wound of bulk foil types are the best for noise performance.
No. The voltage coefficient of noise in carbon composition resistors is 300. In metal film it is 1. So CC are the highest noise, by two orders of magnitude.Comp resistors are the lowest noise
I would instead use a metal oxide resistor as a plate load. They are available in appropriate power ratings from the usual suspects (Digi-Key and the Mouse) and they can be overrated so that the heating due to power dissipation and their voltage coefficient of resistance are low.
The higher the power rating of a resistor, the physically larger it is, and the higher its voltage rating. This helps to cut down the resistance change induced by the voltage gradient across the resistor.
The higher the power rating of a resistor, the physically larger it is, and the higher its voltage rating. This helps to cut down the resistance change induced by the voltage gradient across the resistor.
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I have used several 1/4 was metal film resistors in series as plate loads. The resistances add up to the amount I need, and the wattages add to the amount I need, too. The little resistors are readily available in a wide range of resistances.
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