Buffer/Booster for H&K Red Box Pro

[Bill Mountain]

I picked up a used Red Box Pro and I want to experiment with it on my pedal board.  I was thinking of running it after a few different dirt pedals as a cab sim before hitting a recording interface or for running to the board when playing at decent clubs.  I'm a bass player so the original purpose of this DI is moot.  I'm going to email H&K to find out the maximum wattage it can handle but I doubt I'll want to use this on the output of my Hartke.  If I have a Super Bass or SVT then it might be a different story.

Anyway...

According to this: http://www.hexeguitar.com/schem/Redbpro.pdf the input impedance at line level with the speaker sim on is 5k.  I tried to follow the signal path in the schematic to verify but I am having trouble following the circuit.  I get the gist of it but it's still confusing.  What I'm also not able to tell is what sort of signal loss there is.  I know the transformer is -6db but the speaker sim has to be lossy as well.

All of this is to ask whether a standard MXR Micro Amp will sufficiently drive this or would I need a more sophisticated buffer?  A booster would only be necessary if the sim is excessively lossy.

I thought about doing something with a 386 chip but I already have the Micro Amp (my most used pedal ever).

Some simple experimentation would answer my questions but I'm away from my bench for a while and I thought this might make for an interesting discussion.

[pappasmurfsharem]

The Redbox does not have a dummy load in it.

So it doesn't "Handle Watts" per se.

You have to connect a speaker to the speaker output then run the XLR to the mixer.

If you want to use Line out on your amp then flip the switch to the Line IN Position, however depending on your AMP you will still need to have a speaker load or you can hurt things.

May not matter if you don't have a tube amp.

The Speaker In and Speaker Through options are "directly connected" Your amp isn't going to hurt it.

If you intend to use the Line in input you need a Line Level signal, which I don't think will work with just a micro amp. It would basically be the same as running your bass to a micro amp to the board. Just depends on the mixer has a Hi and Low Z option.

[Bill Mountain]

The Redbox does not have a dummy load in it.

So it doesn't "Handle Watts" per se.

You have to connect a speaker to the speaker output then run the XLR to the mixer.

If you want to use Line out on your amp then flip the switch to the Line IN Position, however depending on your AMP you will still need to have a speaker load or you can hurt things.

May not matter if you don't have a tube amp.

The Speaker In and Speaker Through options are "directly connected" Your amp isn't going to hurt it.

If you intend to use the Line in input you need a Line Level signal, which I don't think will work with just a micro amp. It would basically be the same as running your bass to a micro amp to the board. Just depends on the mixer has a Hi and Low Z option.

If I were to run it in line with my speaker wouldn't some of the components see a few watts of the 500+ that is going to my cabinet?  I want to make sure I don't burn any components up when I do that.  Why do I have to have a line level signal?  Are you suggesting that the Red Box attenuates the line level down to microphone level?  Whats the difference between line level and the 1V+ signal that's coming out of a fuzz pedal? Using the Red Box would be different than running the Micro Amp to the board because it would be a balanced signal and it would have a speaker sim engaged.


Edit: I hope I didn't sound too aggressive with my response.  These are just the questions I had in my head after I read your post.

[pappasmurfsharem]

If I were to run it in line with my speaker wouldn't some of the components see a few watts of the 500+ that is going to my cabinet?  I want to make sure I don't burn any components up when I do that.  

You would run the LINE OUT on your amp to the LINE IN/SPEAKER IN on the Red Box (with the line in switch engaged)
That is if your amp has a line out option, which I would assume if it did you wouldn't use the redbox

Speaker out and Line out are not the same thing. Line out is generally just the preamp output at line levels.

The 500watts would come from the speaker output on your amp not the line out.

So if you are running from the speaker out then switch to the SPEAKER IN mode and run the speaker out(on amp) to the Speaker input (on red box) then the speaker out( on redbox) to your cabinet.

Then the XLR (on redbox) out to the mixer.

If you have a Solid State amp you shouldn't need to have a speaker connected (you will still want Speaker Out selected from the redbox swtich) if you have a tube amp you will need to have the cabinet connected or risk blowing your amp.

Why do I have to have a line level signal?  Are you suggesting that the Red Box attenuates the line level down to microphone level?  Whats the difference between line level and the 1V+ signal that's coming out of a fuzz pedal?

Perhaps I mistyped the XLR output on the redbox outputs a Balanced Low Z (typical dynamic mic level)

If you intend to run direct from a pedalboard to a mixer then the redbox is expecting a line level input (with the LINE IN switch engaged). Guitars do not generally output LINE LEVELS.

Line Level is what you would see from a CD Player or MP3 Player.

Using the Red Box would be different than running the Micro Amp to the board because it would be a balanced signal and it would have a speaker sim engaged.

You can run direct through the redbox, but you would have to bring your effects to LINE LEVEL first then run the Redbox to the board.

It would be similar to running the microamp to the board because the redbox does not control level it it attempts to keep some sense of unity output with the input.

Pedals just don't push enough juice.


You could run something like this after your effects to the RedBox
tagboardeffects.blogspot.com/2013/01/mxr-headphone-amp.html‎

BTW what hartke do you have? Exact model if you don't mind.

[Bill Mountain]

If I were to run it in line with my speaker wouldn't some of the components see a few watts of the 500+ that is going to my cabinet?  I want to make sure I don't burn any components up when I do that.  

You would run the LINE OUT on your amp to the LINE IN/SPEAKER IN on the Red Box (with the line in switch engaged)
That is if your amp has a line out option, which I would assume if it did you wouldn't use the redbox

Speaker out and Line out are not the same thing. Line out is generally just the preamp output at line levels.

The 500watts would come from the speaker output on your amp not the line out.

So if you are running from the speaker out then switch to the SPEAKER IN mode and run the speaker out(on amp) to the Speaker input (on red box) then the speaker out( on redbox) to your cabinet.

Then the XLR (on redbox) out to the mixer.

If you have a Solid State amp you shouldn't need to have a speaker connected (you will still want Speaker Out selected from the redbox swtich) if you have a tube amp you will need to have the cabinet connected or risk blowing your amp.

Why do I have to have a line level signal?  Are you suggesting that the Red Box attenuates the line level down to microphone level?  Whats the difference between line level and the 1V+ signal that's coming out of a fuzz pedal?

Perhaps I mistyped the XLR output on the redbox outputs a Balanced Low Z (typical dynamic mic level)

If you intend to run direct from a pedalboard to a mixer then the redbox is expecting a line level input (with the LINE IN switch engaged). Guitars do not generally output LINE LEVELS.

Line Level is what you would see from a CD Player or MP3 Player.

Using the Red Box would be different than running the Micro Amp to the board because it would be a balanced signal and it would have a speaker sim engaged.

You can run direct through the redbox, but you would have to bring your effects to LINE LEVEL first then run the Redbox to the board.

It would be similar to running the microamp to the board because the redbox does not control level it it attempts to keep some sense of unity output with the input.

Pedals just don't push enough juice.

You are correct.  I was just using my amp as a reference as to why I want to know the max wattage that is recommended.  If I have access to an SVT I wouldn't be using the line out.  But on my amp I would be.

Guitars don't put out line level but some effects surely can.

When you say that effects don't have enough juice are you saying that line level signals have more current or voltage?

[pappasmurfsharem]

That I don't know. I just know it wont work per se. Impedance voltage blah blah. Its all greek to me.

Yes some effects can output at line levels, but I would imagine you would get some tone loss with the impedance issues.

However if you are asking if the redbox can handle the SVT i'm fairly certain yes.

The speaker in and out portion are directly connected nothing should get hurt in the process.

However it's not geared for bass so tonally you will lose some bottom end.

A bass specific DI would be much better for you needs. Or a Sansamp Bass DI, SVT tones direct to board.

I don't recommend spending the extra money on the 3 channel one though. I have it and I swear the digital POTS don't allow the same tone as my single stomp one. It was also noisier to my ears.

[Mike Burgundy]

http://www.diystompboxes.com/smfforum/index.php?topic=103006.0
As Papasmurf said, it's aimed at mimicking a guitar cab so you might not get the sound you wnat, but it'll work just fine. Just make sure the speaker is connected.