Minirec issue in Modern Mode

[robotik]

Hi all,

My mini rectifier modern mode is experiencing volume drop if the volume and/are gain knobs are in 9 o clock position or lower. This happens only in modern mode in both 10w and 25w. The other modes (clean, pushed, vintage) are all fine. Any idea on the possible problem?

 

[elvis]

Could be hop-off. When a potentiometer gets to either extreme, it can lose electrical contact and go high-resistance, which gives a fast signal drop. You may not notice in other modes either because you run the volume and gain higher (modern mode is inherently much louder) or possibly the pots are ganged, with a different internal circuit for each mode.

 

[Authorized Boogie]

Could be hop-off. When a potentiometer gets to either extreme, it can lose electrical contact and go high-resistance, which gives a fast signal drop. You may not notice in other modes either because you run the volume and gain higher (modern mode is inherently much louder) or possibly the pots are ganged, with a different internal circuit for each mode.

+1! This is my thought exactly...

 

[robotik]

Can this be solved by cleaning the pots? If replacement is needed, what pots are needed? I noticed this issue only last week at bedroom level.

 

[Authorized Boogie]

Its not a dirty pot. When you are at the very extreme end of the pot, the wiper can lose contact with the pad - which will result in signal loss. The pots were not meant to be used at such low settings, so this can be an issue anytime you are at the extreme ends of the pot sweep. Thanks!

 

[elvis]

Best bet is to put an attenuator in the FX loop. Something clean, like an EQ set all flat for example, with the output level turned down.

 

[robotik]

So the issue is normal in modern mode? Nothing to do to resolve it? Not a big deal to me but just curious. Thanks for your responses.

 

[elvis]

I think so. The amp is not designed to run at whisper-quiet volumes. It was definitely not designed to be a practice amp.

If you want to run VERY low volume, I recommend a dummy load box like a cab clone with a direct out into a small powered monitor or a home stereo system. That works really well. And you can crank it up a bit so you're not running an anemic signal into the power stage.

 

[KiwiJoe]

Can this be solved by cleaning the pots? If replacement is needed, what pots are needed? I noticed this issue only last week at bedroom level.

I gig with my Mini Rec with low-gain and high volume, so I had been running my gain around 9 o'clock (and the volume around 2 o'clock). I found the adjustment of the gain knob really spikey down low in the range like that, for just the reasons that have been outlined in the posts above. I switched to a 12AY7 in V2, and that made all the difference in the world. Now, I have the same gain level with the knob around noon as I did before with the knob around 9 o'clock, but I now have all kinds of fine adjustability below noon to really fine tune the amount of gain. You might want to consider that option.

 

[robotik]

I'll try swapping 12ay7 in V2. Thanks for the suggestion.

I observed lately that issue lies on the volume pot. The gain pot's sweep works well. The modern mode has very big volume difference to vintage mode and channel 1.