Volume too sensitive on my Spider IV Guitar Amp

[JonathanAnon]

Hi guys,

I have a Spider IV Guitar Amp 75W that has basically no sound between 0 and 1.5 on the main volume knob (which goes up to maximum 10), then once it goes above 2 the volume is waaaaay too loud... I end up spending ages trying to tinker between about 1.8 and 2 to try and find the level I require... Realistically I would never need the sound higher that 2.5 on the amp settings...

I'm thinking of introducing a similar value pot in series with the current volume pot as a sort of overall amp master volume, adjust this pot to the resistance value where the main volume knob gives me the range of sound volumes that I require between 1 and 10 on the main volume pot.. Is there any problems I should look out for... ?

(Also when I find that resistance value that gives me the range of volumes that I am looking for, I intend to just solder in a resistor in place of the second pot so the value cant be changed by accident)

All opinions appreciated.. thanks..

[t.j.]

Re: Volume too sensitive on my Spider IV Guitar Amp

does the guitar not have a volume control on it? cause it should not be that sensitive !

[JonathanAnon]

Re: Volume too sensitive on my Spider IV Guitar Amp

Nah T.J., it's nothing to do with the volume on the guitar... I guess I should have a bought the 30W version of the amp, but I just need to work with what I got now... No money :-(

[t.j.]

Re: Volume too sensitive on my Spider IV Guitar Amp

does not the drive control the input from the guitar? put a couch cushion in front of it! lol... jk... there has to be a way to adjust it to do what ya want with out hard modding it!

[smason]

Re: Volume too sensitive on my Spider IV Guitar Amp

You have it on "insane"

Are you talking about the master volume?

[JonathanAnon]

Re: Volume too sensitive on my Spider IV Guitar Amp

Yeah it's the master volume switch..

[smason]

Re: Volume too sensitive on my Spider IV Guitar Amp

I wonder if it's just dirty. I can't imagine Line 6 designing it that badly.
My Marshall 8240 needs a serious pot cleaning the master crackles and goes from quiet to blow the doors off. I rarely use it, so I've been procrastinating.

[999999999]

Re: Volume too sensitive on my Spider IV Guitar Amp

Yes you could add a resistor, but to replicate the Pot setting you need two resistors to act as a voltage divider. On the second pot you adjusted you would measure between the wiper and input for a resistor between signal input and the (main pot, or if placed after the main pot then between it and amp input) and between the wiper and ground for a 2nd resistor you place between signal and ground.

I know nothing about this amp, BUT there may be another solution that leaves you with higher SNR, to instead reduce the gain of the amp circuit. Whether that is easy or hard depends on how it is designed, if it uses an IC power amp chip it may be pretty easy. It would sound "better" from a purist audio point of view, but I'm not sure if this matters on a guitar amp as much.

[JonathanAnon]

Re: Volume too sensitive on my Spider IV Guitar Amp

Yes you could add a resistor, but to replicate the Pot setting you need two resistors to act as a voltage divider. On the second pot you adjusted you would measure between the wiper and input for a resistor between signal input and the (main pot, or if placed after the main pot then between it and amp input) and between the wiper and ground for a 2nd resistor you place between signal and ground.

I was working this out in my head, and like what you are saying the only way it would have worked practically would to have replaced (say) a 500k volume pot with two 250K pots... If I'd just added another 250K pot in series with the existing pot, I would have shifted the 0 settings up to about 3 or 4 (I think)....

Anyway, I opened it up today... to make a start on my alterations... however, the pot is soldered in to a PCB, a small PCB.... It's too high risk, and there IS NO ROOM to introduce another component... This forces me back to looking at software solution... :-(

Hey just as a theoretical suggestion here (and not something that I would ever intend on doing), if I put a 4 ohm resistor in series with the output speaker it should drop half the voltage across this, but I'm assuming no such resistor could possibly exist that could dissipate that amount of power as heat?

[budm]

Re: Volume too sensitive on my Spider IV Guitar Amp

Can you verify if one end of the pot if you look from the front, the left terminal should be connected to ground if it is setup as volume control not Gain control. If one end is grounded, then use the Ohm meter between Ground and the center viper pin and see if the resistance vary when you adjust between FCW (Full Clockwise) and FCCW (Full Counter Clockwise).

[spleenharvester]

Re: Volume too sensitive on my Spider IV Guitar Amp

Are you just using it for bedroom-level volumes mate? If so it might just be you bought one that was a bit too loud I have a 40W Valvetronix and you can hear it outside with the volume on 4.

[JonathanAnon]

Re: Volume too sensitive on my Spider IV Guitar Amp

Been toying around with this, and the only conclusion that i can come to is to set the volume level on the individual patches and then ignore the volume pot...

What I have also noticed is that the volume pot works as follows... nothing up until 1, moves between 0-100% volume between 1 and 2.5, and then stays at 100% the rest of the way up the pot to 10..

Why in god's name did they do this? Did they use the wrong pot (maybe linear instead of log?)... I've looked up the line6 forums and a number of people have the same issue, so it's not just mine.