Reamping question

[TimWaldvogel]

I have made a diy reamp box in the past using the schematic on the Jensen transformer site. I used an edcor pc10k:10k instead

I gave that one to my brother and
I have an idea of using a existing guitar pickup as a inductor in the circuit for a more realistic sound for reamping maybe? 

I also am looking for a schematic for a active reamp box. 
Can you guys help me out and maybe throw around some ideas?

[DougH]

Try it with no reamping at all first. You may find it's effect is minimal. Amp input is high Z.

[boogietone]

Assuming that you are recording a direct guitar or bass signal for reamping, the influence of the pickup and all other guitar bits and pieces is already in the recorded signal. You generally want the reamp box to be a low impedance source and as clean as possible.

If you are interested in sending the signal to a "load sensitive" device, replicating a guitar pickup - tube amp interaction for instance, I would build a circuit to replicate the loading sensitivity as a separate effect to be placed between the reamp box and the amp/pedal. You could put the circuit in the same box, of course, with a selectable output. This is useful only if the first amp or effect that is getting the signal is actually load sensitive. A high impedance input, including most buffered pedals, will negate any efforts here.

[wavley]

This might help


http://www.hansenaudio.se/techpage.htm#active%20DI-box,%20my%20work%20horse%20from%201975

[TimWaldvogel]

Has anybody built an active reamp Using the AMZ pc boards for buffers etc?

[DougH]

I thought the point of reamping was to provide a high Z source to mimic a pickup?

[ashcat_lt]

The point of reamping is to run a pre-recorded signal out through an amplifier, though the term is sometimes used when just running out through pedals.  The point of the reamp boxes is to provide attenuation - to bring line level signals down to guitar level so the amplifier(/pedals) will respond as expected - and to provide isolation to avoid the possibility of ground loops between recorder and amp.

[wavley]

I thought the point of reamping was to provide a high Z source to mimic a pickup?

My favorite way to do this is to use a passive di in reverse, so yes, at least the way I look at it.  Of course, it's very rare for me to reamp a guitar, sometimes I reamp something that my bass player who temporarily lives two states away recorded direct and emailed me, so I'll run it through his amp here, usually it's because I want to mash up drums or run keyboard parts that I recorded direct so I wouldn't bother my wife through an amp or space echoes.

[boogietone]

Reamping is a old production technique where a prerecorded signal is sent out to an effects chain and or amp and rerecorded.

The term applies to anytime you send a signal to outboard gear but it is usually used to mean a dry guitar or bass part that is sent to an actual amp with a speaker moving air and rerecorded. I would say that its main purpose is to take the line level from the board down to an instrument level signal that is best for an amp, etc. But, you can send drum hits through a bass amp, a vocal part through an EP-1, or add bathtub 'verb to a guitar solo.

A reamp box could simply be a DI box run backwards or something active like Radial's X-Amp (http://www.radialeng.com/di-xamp.htm).

There are many reasons to do this. It allows selection of amp/speaker/mic combinations after the fact, recording in a bedroom at night and then getting the amp tone at the studio or when the neighbors won't complain. If you only have a small board, reamping allows you to have the same part (re)recorded though multiple effect/amp chains or the same amp with different mics/mic positions for a thicker sound using the same board input.

The output impedance could be whatever you wanted. For a guitar signal, it could be made to mimic a pickup. The X-Amp's output impedance is on the order of 5K.

[TimWaldvogel]

Can a typical op amp handle a line level signal without clipping?

I'm trying to figure out how to build an active DI mostly.

My old reamp box was cool but I want to build another one.

The idea for the guitar pickup as an inductor was merely an attempt at have an accurate resistive and inductive load on the signal opposed to just having a resistive load on the signal going into the guitar amp. I don't have inductors laying around, but I Do have guitar pickups laying Around. Would this help in an passive unit?

Is there an available schematic for an active reamp box?

[Perrow]

Can a typical op amp handle a line level signal without clipping?

I'd say yes, given high enough Vcc and low enough gain there should be no problem.

[petemoore]

Can a typical op amp handle a line level signal without clipping?
  First: What is atypical or line level ? Then Yeaprobly...these types of opamp circuits will have 15+/15- split supply to accomodate higher voltage signal peaks.
  I'm trying to figure out how to build an active DI mostly.
  It sounds like it'd be easy as anything else to build save the jack mounting, perhaps just buying something'd be good.
My old reamp box was cool but I want to build another one.
The idea for the guitar pickup as an inductor was merely an attempt at have an accurate resistive and inductive load on the signal opposed to just having a resistive load on the signal going into the guitar amp. I don't have inductors laying around, but I Do have guitar pickups laying Around. Would this help in an passive unit?
  Old wah inductor ? or just a Radio Shack one ? See AMZ for pickup simulator/inductor circuits for guitar FX.
Is there an available schematic for an active reamp box?
  Perhaps, or an amalgum of schematic fragments could be fitted to 'reamp box'.
   Terms tend to confuse me, what a re-amp box even 'is' would be better illustrated with a schematic, otherwise starting with a block diagram to demonstrate the intents and needs of the circuits goals.

[artifus]

Terms tend to confuse me, what a re-amp box even 'is' would be better illustrated with a schematic, otherwise starting with a block diagram to demonstrate the intents and needs of the circuits goals.

http://en.wikipedia.org/wiki/Re-amp

*edit* http://www.jensen-transformers.com/datashts/6110kb.pdf

[wavley]

My question is, what kind of interface are you using to drive this thing?  Then we can worry about if the op-amp will clip or not and other such matters.  For example: my Motu 896HD has balanced outs that can be switched from +4 to -10dB and fine tuned in the software from there so I really don't have to worry about clipping anything on the output.  Personally, depending on your interface, I don't see much of an advantage to an active circuit here if you have balanced outs that are perfectly capable of driving a transformer, plus the CMRR of a transformer is pretty danged good.  So I would just keep on using a passive box with my long run of cable would be balanced and my short one unbalanced.  Edcor makes some pretty decent transformers for pretty cheap and you can even chose one that has some attenuation built in.

Or you can do an electronically balanced circuit and ditch the transformer all together if you want, I suppose the advantage of that is that you can build in some tone shaping.

[Jazznoise]

I use one of those Thomann DI Boxes (10 euro) backwards and it does the job more or less perfectly.

But I'll let you decide as some of my freinds have been sceptic so I made an A/B comparison. Same amp, same settings, same mic, same distance, same recording. Be aware that you have to watch your mixer outputs, I had my aux about less than halfway.  http://soundcloud.com/jazznoise/recording-vs-re-amp

[wavley]

I use one of those Thomann DI Boxes (10 euro) backwards and it does the job more or less perfectly.

But I'll let you decide as some of my freinds have been sceptic so I made an A/B comparison. Same amp, same settings, same mic, same distance, same recording. Be aware that you have to watch your mixer outputs, I had my aux about less than halfway.  http://soundcloud.com/jazznoise/recording-vs-re-amp

It's funny, because I have several DI's active and passive ranging from cheap up to an Anthony DeMaria Tube DI and hands down my favorite thing to reamp with is a cheap passive DOD from the 80's run backwards and my second favorite is the radio shack impedance matcher run backwards.

[artifus]

funny thing, taste. always makes me laugh when i see 'what's the best...' threads! i prefer the word 'different'

[ashcat_lt]

I use one of those Thomann DI Boxes (10 euro) backwards and it does the job more or less perfectly.

But I'll let you decide as some of my freinds have been sceptic so I made an A/B comparison. Same amp, same settings, same mic, same distance, same recording. Be aware that you have to watch your mixer outputs, I had my aux about less than halfway.  http://soundcloud.com/jazznoise/recording-vs-re-amp

I can't tell a difference from listening, at least not the way this is presented.  Neither is any "better" to my ears.  I've downloaded it to play around and compare in a bit more "scientific" way for fun. 

Any chance you could do me a favor and run one more pass straight from the mixer to the amp w/out the DI?

[artifus]

to compare two signals in your daw pan both centrally and reverse the phase (polarity) of one or the other. the result you observe is the difference.

ie - two identical signals should cancel each other out completely. silence.

[boogietone]

I found the reamped (2nd) version to be a bit fuller/warmer. Just looking at the waveforms in soundcloud shows that they are not exactly alike.

What kind of amp and what kind of gain structure did you use into it?