Tube DI current rating & question

[skyline_01]

MODS: Please move if wrong category!

OK, so I just got a Sushi Box Finally tube DI and its current rating is 500mA for warmup, 250mA continuous. I don't have a dedicated wall plug for it and will be powering it with an under-pedalboard unit.

Question is, should I use a 500mA output or will a ~250mA handle the warmup period? I've got an email in with Sushi Box but haven't heard back yet (I'm sure he's hella busy making dope pedals). I think I may know the answer but welcome some expert input.

Many thanks!

 

[eeyorebass]

I'm not an expert, but I think this is a case where more is more better. If you can spare the 500ma output, put it there.

 

[bassbrad]

Hey @skyline_01 we have an active group for @Sushi Box FX and this is a FAQ that many members can answer for you.
250ma will be fine but it will take a bit longer to warm up, in my experience usually it's 30-45 seconds a lower power might take 90-120 seconds.
Join us at:
The Sushi Box FX Secret Society

 

[skyline_01]

Hey @skyline_01 we have an active group for @Sushi Box FX and this is a FAQ that many members can answer for you.
250ma will be fine but it will take a bit longer to warm up, in my experience usually it's 30-45 seconds a lower power might take 90-120 seconds.
Join us at:
The Sushi Box FX Secret Society

Oh, this is very helpful! Thanks for the info!

 

[Sushi Box FX]

Sorry, must have missed the email. I get a good handful of those and try to keep up, but sometimes they slip through unnoticed.

As for the actual minimum current required, it completely depends on how the power supply is designed. For instance, I have two power supplies from different manufacturers with the same current limit of 1700mA. One supply has been tested up to 2000mA and it still runs fine, if a bit warm. The other has had issues supplying 1000mA to a power-hungry tube pedal.

So every supply has a current limit, but in some cases it's a loose limit, where if a pedal tries to pull more than that it will sag for a bit then stabilize when the tube has heated up. Other supplies however have an overcurrent lockout, where they absolutely will not supply more than the current stated on the label. If this is the case, you'll likely see the LED blink on every couple seconds as the supply shuts down and comes back up in an attempt to check and see if the power-hungry device has been removed, and will never successfully boot. Where 250mA is the actual current draw of the pedal once the tube has warmed up, I would be really nervous about using a 250mA rated supply with it. So I won't promise that it won't work, but I will say that I have seen damage to power supplies and pedals from under-spec'd supply use.

 

[skyline_01]

Sorry, must have missed the email. I get a good handful of those and try to keep up, but sometimes they slip through unnoticed.

As for the actual minimum current required, it completely depends on how the power supply is designed. For instance, I have two power supplies from different manufacturers with the same current limit of 1700mA. One supply has been tested up to 2000mA and it still runs fine, if a bit warm. The other has had issues supplying 1000mA to a power-hungry tube pedal.

So every supply has a current limit, but in some cases it's a loose limit, where if a pedal tries to pull more than that it will sag for a bit then stabilize when the tube has heated up. Other supplies however have an overcurrent lockout, where they absolutely will not supply more than the current stated on the label. If this is the case, you'll likely see the LED blink on every couple seconds as the supply shuts down and comes back up in an attempt to check and see if the power-hungry device has been removed, and will never successfully boot. Where 250mA is the actual current draw of the pedal once the tube has warmed up, I would be really nervous about using a 250mA rated supply with it. So I won't promise that it won't work, but I will say that I have seen damage to power supplies and pedals from under-spec'd supply use.

No worries about the email thing - I just appreciate you weighing in on this!

I'll definitely be using a 500mA source then. But if you'll indulge another question - is there any discernible difference between using 9v and 12v?

Many thanks again!

 

[Sushi Box FX]

No worries about the email thing - I just appreciate you weighing in on this!

I'll definitely be using a 500mA source then. But if you'll indulge another question - is there any discernible difference between using 9v and 12v?

Many thanks again!

Nope, the only difference will be the actual temperature of the tube, 12V will get it hotter. The tube will see the same high voltage level regardless of input voltage.

 

[amper]

MODS: Please move if wrong category!

OK, so I just got a Sushi Box Finally tube DI and its current rating is 500mA for warmup, 250mA continuous. I don't have a dedicated wall plug for it and will be powering it with an under-pedalboard unit.

Question is, should I use a 500mA output or will a ~250mA handle the warmup period? I've got an email in with Sushi Box but haven't heard back yet (I'm sure he's hella busy making dope pedals). I think I may know the answer but welcome some expert input.

Many thanks!

You absolutely must use a higher current output to handle the inrush current when it is switched on. Once the tube is heated up, then it will draw less current.

 

[amper]

No worries about the email thing - I just appreciate you weighing in on this!

I'll definitely be using a 500mA source then. But if you'll indulge another question - is there any discernible difference between using 9v and 12v?

Many thanks again!

The heater voltage of a 12A-series tube is specified to be 12 V, so your pedal should be regulating the heater voltage, regardless of what voltage power supply you use. It should not make a difference.

 

[Sushi Box FX]

The heater voltage of a 12A-series tube is specified to be 12 V, so your pedal should be regulating the heater voltage, regardless of what voltage power supply you use. It should not make a difference.

The pedal does not regulate the heater voltage, but based on my testing 12A*7 family tube heaters can be run down to about 8V before you start actually hearing a difference, so I have no problem telling people to run my pedals at 9V or 12V because you won't hear a difference.