How to reamp into preamps (repreamp?)

[Paul W]

I'm thinking of doing some controlled experiments on preamps and it seems like it ought to be easy (in principle) to play mic-level recorded signals into preamps for very controlled experiments.

I'm familiar with reamp boxes that generate instrument-level signals for guitar amps and pedals, but I don't recall hearing about re-preamping boxes that generate mic-level signals.

Is that a thing? How would I go about that?

Related question: are there any archives or other good sources of pristine recordings of mic-level signals (presumably through high-end "clean" preamps and converters), for such experiments?

It seems like there ought to be, and it ought to be comparatively easy to compare preamps (at least relative to things like compressors), running varied standard clips through them at different gain levels to see what "color" you get (or not). (And maybe with a few different output impedance levels from the repreamp box?)

 

[pmfalcman]

A passive DI box?
They're meant to convert hi-Z line output to low-Z mic level after all, right?
Unless the hi-Z to low-Z part causes issues it should do the trick.

 

[Khron]

They're meant to convert hi-Z line output to low-Z mic level

* instrument output

(Line-to-mic, especially if galvanic isolation is not necessary and/or the line-level source is balanced, can simply be achieved with a resistive pad / attenuator)

 

[emrr]

Line to mic pad. ‘U’ pad with 40-50dB loss. Don’t overthink it.

 

[Rob Flinn]

There are a few DI boxes that already do this.

For example this Hughes & Kettner one.
https://www.ebay.co.uk/itm/256715023977?_skw=di+box&itmmeta=01JCQYZ4504A990KA0X04E01R2&hash=item3bc5686669:g:AgYAAOSwJAtnNVTL&itmprp=enc:AQAJAAAA4HoV3kP08IDx+KZ9MfhVJKkAPXzDIyiXGUUET0pJkqlYvYzT6D5ST8vNhAyANeQi2n3k8/XxvshPDoxRN8AT+5D37uPqakMDNDZS8h85/I8--hW2xPa97GMKyGCIQrYcH/2p/CHpX8YWUu1wGZhDkRnAfyA9GXjH3GX4/8LREfHl51tJNuNf+YKg0ZmCIrAMuCHZ3L3pKP7pnrNh0GmdMZb8EwoFasZxLwMdEhsPzn3g7giS+bYKdmeheKJMoBpQAItJkIzw7wE+/NJozvuFxm/rq/fkqxymwiFGhwQop--n|tkp:Bk9SR8rC_P7lZA

or this MTR one

https://www.ebay.co.uk/itm/25671476...ztpQkENivQBgHBp7jj/WEC8A==|tkp:Bk9SR8rC_P7lZA

 

[pmfalcman]

* instrument output

I stand corrected.
I took a shortcut -> instrument level hotter than mic level = ~line level.

 

[kingkorg]

I'm thinking of doing some controlled experiments on preamps and it seems like it ought to be easy (in principle) to play mic-level recorded signals into preamps for very controlled experiments.

I'm familiar with reamp boxes that generate instrument-level signals for guitar amps and pedals, but I don't recall hearing about re-preamping boxes that generate mic-level signals.

Is that a thing? How would I go about that?

Related question: are there any archives or other good sources of pristine recordings of mic-level signals (presumably through high-end "clean" preamps and converters), for such experiments?

It seems like there ought to be, and it ought to be comparatively easy to compare preamps (at least relative to things like compressors), running varied standard clips through them at different gain levels to see what "color" you get (or not). (And maybe with a few different output impedance levels from the repreamp box?)

It depends on what you are trying to do.

In lots of cases "color" will depend on mic output stage>pre input stage interaction.

If you are emulating say Neumann TLM mic into a pre, then you can just plug ballanced output of your interface into whatever pre you are testing. TLM has low impedance output and is no different to whatever interface you have. You just varry the output level of your interface, why would you even need anything in between?

If you want to emulate sm57, then you have to emulate the output impedance and transformer performance. Sm57 will behave differently depending if pre is transformer coupled. This goes for most transformer coupled mics, and it's where lots of the "vibe" comes from.

My 1176 into La2a chain creates weird HF roll-off which i like. If i test both of the devices on their own, it is not present. The "magic" happens between 1176 output, and La2a input transformers.

Just done with k67 testing, and unity gain mics at least in theory, can put out 25Vpp, so i don't think you need attenuation att all, you just use output slider. Doug Ford confirmed this to be the case when Røde NTK circuit was designed and tested.

 

[kags]

I just did a shootout with some students of an SM 57 into a handful of different preamps, some with variable impedance (ISA, API512, Neve 1073, Warm wa12, summit, SUPRE, Chandler) and the 57 really sounds different into different pres/impedances.