I feel somewhat maligned by that comment My advice to anybody here is if you have an idea, theory, concept whatever..just try it. You will gain experience.
For a single input tube guitar amp, mostly they are 1 Meg input Z.
For a guitar amp with 2 inputs (Low/High): The jack# 1 high level input is Z=1Meg or around that. What happens on the low level input is you have a switched in voltage divider attenuator (also work as grid stoppers), typically 68K+68K, where the grid sees 1/2 the signal voltage level (-6dB)...but also the bottom resistor is grounded when the Low jack is used. There is an input impedance now down more than a factor of 10. Still works, although it does change the ''tone'' a little bit. Nothing drastic really, you could still boost up highs to compensate on the tone stack. It will, however, really start to suck tone if you dial down your guitar volume pot. Again it is playing on the whole source and load response.
SO I throw the question out there: is 1 Meg the ''right'' answer? Is below 100 K still working? If you have a Fender Twin or a Marshall Plexi , both would be right IMHO.
'Right' is probably the wrong word?, I would suggest a minimum of 1Meg, with more preferable (1Meg is a bit low if the guitar has 500K pot's). Lower values certainly 'work', but it affects the tone and the output level - and 'could' be preferable in some circumstances?.
I own a Fender KXR60 keyboard combo (1x12 speaker), this has two input channels, both balanced and only 18K input impedance. We once used it for a small gig with a passive bass plugged in one channel, and a passive guitar plugged in the other
Not something I'd recommend, and while the 'tone' might have been affected it wasn't affected as much as not having any amp at all. But as there was nothing to compare it with, who's to say the tone was affected?.
It was a VERY sudden gig, dropped on us at 30 minutes notice, and it was a question of trying to find 'something' to play through.
That was the point I was making exactly.
''Right'' answer is not an absolute, 100K or even 68 K is still workable..because they have put it in Hi/Low option for Fender and Marshall amps with 2 channel input. 1 Meg for a guitar is pretty much the standard, and most cases the better option. For a bass, I am not sure how the response is affected..that is why trying it would be a good thing. I like hearing bass with a significant amount of high end rolloff, so the transformer idea 'could' be a good thing. Twangy bass interferes with my twangy guitar playing!
lol i like that. I too prefer dark dub reggae bass tones. Tho to me the best way of getting this is to use the tone pot. If this isnt sufficient, then change the cap on the pot from .01uF to .022uF for example. Loading of pickups does more to the tone than simply killing highs and presence peak...
Sorry about that. I thought, perhaps, from the context you'd realise it wasn't directed at you. I was trying not to point a finger, nor brag about my own experience, but maybe that was the wrong approach.
1 Meg is the right answer if you want to please the greatest number of people. As I said in the beginning, it's a matter of taste that can't really be supported by electronics theory. You can explain the reasons it works, but you can't determine the 'right' value with electronic theory alone unless you drag in psycho-acoustic theories about perception and why too high a Q will sound "brittle" or "tinny".
Not to worry, we all have varying experiences. Agree that the 1 Meg is about the best answer for pleasing the most amount of ears, and given the wide array of potential pickups possible. Mondogenerator added a good point as well to what I was getting at, that the transformer acting as an L component, maybe with a cap network could do some interesting things. If you do a 2 transformer approach switching Parallel/Series and put an adjustable RC, could make for some decent sounds (for a bass).
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.