Lab Rat Low Volume Output

ThatDude

ThatDude

Active member
Does the Lab Rat have a lower volume output than the original Rat Circuit? I have to turn the volume almost all the way up to get about unity volume output. Compared to my builds of original Rat circuits it definitely has less volume on the output. I am not sure if that the way Lab Rat circuit is, or if I something is not right with my build.
IMG_1950.jpeg
 
I haven’t built one but what you’re experiencing doesn’t sound right.
Your soldering looks good but has your input jack, ground solder flowed properly?
Also, might be worth swapping tubes to check that’s not the issue
 
SamuelG said:
I haven’t built one but what you’re experiencing doesn’t sound right.
Your soldering looks good but has your input jack, ground solder flowed properly?
Also, might be worth swapping tubes to check that’s not the issue
Click to expand...
Thanks @SamuelG. I’ll check the ground of the input jack and swap tube and see if that fixes it. I’ll report back.
 
Just dusted of my 50year old CRO and with all knobs on 12 o'clock I had the same out as in, with the volume on full I more then doubled the output signal. I like my old CRO with a real cathode ray tube in it.

edit: I just noticed all the dust at the bottom of the screen in the pic, it has been a long time since I used it.
 

Attachments

  • LabRat All Knobs 12 oclock.jpg
    LabRat All Knobs 12 oclock.jpg
    194.5 KB · Views: 8
  • Lab Rat Volume Full.jpg
    Lab Rat Volume Full.jpg
    229 KB · Views: 7
Last edited:
Tassieviking said:
Just dusted of my 50year old CRO and with all knobs on 12 o'clock I had the same out as in, with the volume on full I more then doubled the output signal. I like my old CRO with a real cathode ray tube in it.

edit: I just noticed all the dust at the bottom of the screen in the pic, it has been a long time since I used it.
Click to expand...
Thanks @Tassieviking. Sounds like it’s something in my build. I am going to look into it. I don’t remember the output being that low always. Something probably needs fixing.
 
One thing you may want to check is that the ends of C15 or C16 isn’t grounding on the bottom of the pot.

These pots have metal on the bottom that goes to ground, so if the legs are a bit long signal could go to ground.
 
Re-hashing this thread. I had another tube wear down prematurely. I measured some voltages and it seems like the tube might be getting starved of power and getting damaged. I am measuring 8.89v across pins 4 and 5 of the tube, it seems like the voltage is not getting stepped up to 12v in the circuit. I measured across the circuit and seem to be getting 244v for the B+ line where needed but I am consistently getting 8.8-8.9v on the heater power output. I measure 11.9v when I run the pedal at 12v though. Is this pedal supposed to run off 12v or 9v? I am using a Cioks DC7 for the power supply. I have version 1.1 (12/2023) of the PCB. Thanks in advance.
 
Reading up on this, it sounds like 9v across the heater is the way this is designed. Any recommendations of places I should check to see why tubes would be wearing down in a matter of a few hours of playing time? The pedal is not dead, but there is definitely a volume drop.
 
Most people run these pedals on 9V with no problems but you can run them on 9V-12V if you want, some people prefer to use 12V because they think there is a difference in tone compared to 9V.
The heaters are wired for 12.6V operation but nearly all tubes work fine running on 9V as well, there have been some tubes that do not like 9V on the heaters.
The manufacturers recommended heater voltage for the tubes is 12.6V +-10% so you should be ok with up to 13.86V on the supply to the pedals, if you include the 0.3V drop across the 1N5817 protection diode you can supply the pedal with 14.16V and still be within the tube specifications.

EDIT: What brand and type of tube are you using?
 
Tassieviking said:
Most people run these pedals on 9V with no problems but you can run them on 9V-12V if you want, some people prefer to use 12V because they think there is a difference in tone compared to 9V.
The heaters are wired for 12.6V operation but nearly all tubes work fine running on 9V as well, there have been some tubes that do not like 9V on the heaters.
The manufacturers recommended heater voltage for the tubes is 12.6V +-10% so you should be ok with up to 13.86V on the supply to the pedals, if you include the 0.3V drop across the 1N5817 protection diode you can supply the pedal with 14.16V and still be within the tube specifications.

EDIT: What brand and type of tube are you using?
Click to expand...
Thanks for the reply. The first tube was a JJ, and the second was a Psvane. I’ll running it at 12v with a new tube and see if it lasts longer. For C1 (10uF electrolytic cap) should I be using a 400v cap there? I measured 244v on the B+ line which is close to the 250v limit of the cap I have in there now. Thank you again.
 
I used 250V 10uF on my first build but all after then have been using 400V 10uF, 400V fit fine and they cost the same as 250V so you might as well get the higher voltage ones. I did use 10uF 450V caps on some builds because they were in front of me but they are a tighter fit to get in there.

The 250V rating on the cap is just the rated voltage it can run at, the caps should not have any problem running at 250V all day and they usually have no problem running at more if they need to. I like a better safety margin so I go for a higher rating.

I also use 100uF 50V caps instead of the 100uF 25V caps in the build doc because the footprint on the PCB is for an 8mm diameter capacitor in the supply filtering on all the C2CE builds, makes no difference but the cap sits better on the board with the 50V cap.
 
Last edited:
You must log in or register to reply here.
Back
Top