Talk:Re-amp

Feb 15th 2010 Comments

Several professional reamplification interfaces actually do alter the IMPEDANCE (Z) of the source (in this case the output from DAW or Console, etc). Adding a resistor in series is not really the greatest technical approach as it will change frequency response creating a low-pass filter depending on the amplifier's (or destination) input capacitance and generally simply act as a voltage divider.

The point is to present a reactive source to the amp, so that the amplifier can "load" this source as it does a guitar pickup. In this sense reamping sometimes is ineffective achieving the original intention for three reasons: 1) It does not actually preserve the original source's amplitude. 2) It does not actually preserve the original source's impedance (Z, not just resistivity) 3) It really is a bit overkill. Converting a balanced signal to an unbalanced one is really no big deal, depending on the continent take the two right pins. Reducing amplitude is really no biggie, pull the fader down. As far as for amplifier loading,: the reason why amplifiers (and guitar effects in general) are designed to have a HIGH INPUT IMPEDANCE is so that it does not present a significant load to the pickup. The pickup is considered to be a voltage source. If the amp's impedance is too low it will reduce the voltage present at the pickup because the guitar's output impedance and the amp input impedance really are in parallel when connected. So, if the amplifier input was 300 ohm, then there would be almost no voltage present at it, as the current that flowed through 15kohms before is now flowing into 15kohms || 300ohms which is about 300 ohms. That is why when you connect an electric guitar directly into a microphone input it requires an awful amount of gain, is full of noise, and sounds generally horrible.

So for example, a 15 kOhm guitar pickup (these numbers are just for DC resistance) has a 400 mV output voltage. This would be equivalent to about 26uA flowing through the pickup's coil. That's it! the same 26 uA will be flowing through both pickup AND input stage of whatever load is presented when we connect the guitar to ANYTHING. If the Amp's input impedance is 1 MOhm then the voltage will be 26uA x (1MOhm||15kOhm) = 384 mV (give or take). If the Amp's input impedance is 300 Ohm (typical mic input) then the voltage present there will be about 26uA x (300Ohm||15kOhm) = 8 mV. Pretty simple, pretty horrible. So we are basically dealing with a voltage source, we must thus present a high input impedance. Once the signal is safely stored in a low-output impedance piece of equipment, then this will simply no even be an issue as far as Resistivity. The whole point of a Reamp box is then REACTANCE - but since we cannot keep an impedance map of the pickup, there is no way we can recreate it later. So end of issue. —Preceding unsigned comment added by 186.24.23.1 (talk) 15:01, 15 February 2010 (UTC)

29 August Revisions

With respect to the term "reamp" as used in re-recording via reverse DI techniques, we can find no written evidence of the term prior to 1993. John Cuniberti says he had never seen or heard the word "reamp" before he first coined it in 1993. Actually, he first branded his hand-made units with the word "re-amp" but AMP (the connector company) objected, so he changed it to "reamp." Without written evidence, we must assume (not conclusively, of course) that the word was coined by John Cuniberti. Stronger attribution should appear in the Wiki. "May have" is far too weak.

Have added three sections called "Example of Re-amping" / "References" / "Legal"

- Introductory paragraphs

- An Example of Re-amping

- Advantages of Re-amping

- Electronic Interfacing

- Terminology

- History

- Legal

- Links

- References

Revisions and concerns:

1.) The article stated that re-amped guitars are played only through vacuum tube guitar amplifiers. While this is true much of the time, it is not always true. Revision made.

2.) Re-amping is generally NOT employed during mix-down, but is generally an extension of the tracking phase (unless the studio has run out of tracks!) Revisions made in two areas.

3.) Consoles are not the only downstream "canonical" destination of a DI box. In fact, in today's studio, we frequently find outboard preamps in use, bypassing the console completely. Revision made.

4.) Note that DI boxes do not universally deliver a "high level" signal at their output. Some do, some don't. Some (many) are designed for mic-level output, some live-level. All DI boxes that I'm aware of deliver a balanced signal. Revised for specificity.

4a.) Moreover, "Reverse DI" does not universally describe the converse.

4b.) The article stated "When guitar amp or amp simulator designers try various circuit component values or settings, they can use the dry tracks as prepared, always-available input test signals, and consistent reference signals." This is unclear to me. I've not changed anything here, but perhaps it could be rewritten with more clarity - for example, what is a "reference signal" WRT "dry tracks" and "input test signals?" And how do these all clearly relate to re-amping?

4c.) The article states "Like running a guitar signal through a guitar effects pedal that is set to Bypass, re-amping introduces some degree of sonic degradation compared to playing a guitar live directly into a guitar amp rig." Many electronics devices and pedals offer a true (hard wired/relay/switched) bypass, thus avoiding degradation. This sentence should be rewritten with improved accuracy.

5.) The article states "It converts a balanced to an unbalanced connector, reduces the high +4 dB studio-level signal down to a -10 dB level"

A "connector" is not balanced or unbalanced. Plenty of pro kit uses XLRs that are wired unbalanced (Millennia and GML, for instance), and a great deal of balanced kit use 1/4" phone (TRS) connectors. Revisions made.

The stated "+4dB" and "-10dB" levels have little meaning in a reamping context. A proper re-amping device should reduce the signal level far more than 12dB (roughly the difference between +4dBm and -10dBv). An electric guitar should be seen as having a "nominal" level of around -20dBu to -30dBu, with great variations due to pickup sensitivity, active vs. passive, etc.. Many home studios run nominal "-10", and will still require an adequate reamping path. Too many dB references! Made revision towards clarity and simplicity.

6.) I have removed this: "As "reamp-ing" terminology became popular, the term re-amp or reamp has been used in the guitar amplifier field to describe the approach of running a vacuum tube power amp into a dummy load and then again amplifying the resulting line-level signal back up to a high-power level which drives a guitar speaker."

How common is the word "reamp" when describing a real-time "dummy-down/amp-up" technique? Where is this being used in common vernacular? Books? Magazines?

Postings at thegearpage.com. This is a novel (recent) and interesting usage, not an established common usage. MichaelSHoffman 00:28, 30 August 2006 (UTC)

Need some valid references to show common and accepted usage in the industry. I've checked some of the "power soak" references and cannot find ANY usage of the word "reamp" to describe real-time re-amplifying of a pre-soaked signal. If it's not a real time process, then it is conventional re-amping - not deserving of a separate mention.

It's a real-time process. MichaelSHoffman 00:28, 30 August 2006 (UTC)

If there is broad real-world generic acceptance of the word "reamp" applied to a power soak (or Speaker Soak®) scenario,

In case it's unclear, I've only referred to the Rockman Power Soak, not Millennia Speaker Soak. MichaelSHoffman 00:28, 30 August 2006 (UTC)

... I'm happy to include this - but it needs to cite adequate references. To convince other skeptics (like me), and remain honest historians, we'll need to cite substantial, authoritative references when claiming broad attribution.

7.) Clarified Les Paul section, better syntax, etc.

8.) I've looked around the Internet and find no references which in any way describe "re-recording" onto Berliner master disc cutters by Russolo in 1913. I've removed this citation. If someone finds a primary reference (not secondary), please add it back in and cite the source in the References section.

9.) Bob Olhsson's work, as (confusingly) written, appears to be nothing more than multi-tracking. I've asked Bob about to clarify the story. Pending his answer, I've removed the citation and will re-enter after his clarifications if appropriate to re-amping.

9a.) Roger Nichols tells me that his re-amplification technique was used first in 1968, not 1972. No transformer, just some resistors to link console to guitar amps. We'll report it as a self-citation ("Roger claims"). Made revision.

"Amp fatigue" may mean worn-out power tubes, which is common when pushing power tubes into high distortion for extended periods, and is audible as degradation artifacts such as the sound rising and dropping erratically. Output transformers in a tube guitar amp may arc across their internal windings after enough stress. Other components can become erratic under stress, such as capacitors and resistor solder joints. I haven't heard of speaker degradation, only blowing a speaker entirely. MichaelSHoffman 01:34, 30 August 2006 (UTC)

9b.) Need citation on the Phil Spector / Let it Be re-amping claim.

10.) The article used the word "reamp" (and derivatives) to describe the historical practices of re-recording. We can't re-name historical practices without ample precedent. This is an encyclopedia, not an editorial. Until this Re-amp Wiki was drafted, nobody in the history of audio recording had ever called the work of Shaeffer "re-amping" - nor Stockhausen or Varese (etc.). Today's historians and technical writers refer to the work of Murch and Shaeffer as "re-recording." The patent office refers to such work as "re-recording," and devices which assist in the process as "re-recording devices." As such, enormous historical and encyclopedic precedent must inform this conversation. There is no precedent that supports the use of the word "reamp" to describe the historical re-recording process, nor would great artists like Murch (i'm certain) find this at all an amusing rewrite of encyclopedic history.

I've changed historical references to the term "re-recording" with numerous modern attributions of "re-amping" where appropriate.

11.) No mention is made of Murch coining the term "worldizing." The article characterized the technique of "worldizing" as "adding room ambience to a dry recorded voice." Worldizing is vastly more complex than adding room ambience to voices. Made revision and added Nick Peck quote.

Have respectfully tried to keep as much of the article as possible, but trust these revisions are factually necessary, without getting overly-technical. Let's keep refining until we have a sound, historical document to all be proud of.

Best wishes, John

Generic term usage

There are differences; 'Xerox' is meaningless in derivation.

........

True, but terms such as "re-amp" and "reamplification" were not used in the audio industry until well after the 1994 trademark "Reamp" first appeared. We cannot argue that neo-colloquialisms such as "re-amp" as used to describe an audio re-recording device arose spontaneously. Regardless of its inherently descriptive nature, it is a fact that words such as "re-amp" and "reamplifier" are directly derived from/after the Cuniberti trademark "Reamp." Without the word/trademark "Reamp" having been coined in an audio context, it is far likelier that we would today be using the generic terms "guitar re-recording" or "reverse DI" to describe the specific process of two-pass amplified guitar recording. It's pure speculation to presume the terms "re-amp" / "reamplifier" / "re-amplification" (etc.) would have spontaneous appeared generically on their own.

It would be instructive to have a trademark attorney join this conversation, but my understanding is that, regardless of any inherent descriptive qualities, a trademark and obvious derivatives of that trademark remain in force as long as the trademark owner "enforces" its use. Examples include "escalator" - a descriptive trademark that was in legal force for decades, even though it was used contemporaneously as a descriptive term (today it is generic). Another example is "Band-Aid" - a highly descriptive term that has become a household expression while retaining exclusive, legal trademark rights for its owner. In other words, another company cannot rightfully market adhesive strips called "Band-aid" or some derivative, such as "Bandaid" or "Bandaids." Johnson & Johnson would be all over the infringing party.

The fate of the trademark "reamp" and obvious derivatives (such as "re-amp") rests fully in the hands of its legal owners. If a trademark owner does not vigorously enforce their exclusive identity with the mark (such as through Passing_off), a descriptive trademark will eventually be subsumed into general use. Time will tell. JL