Buffer with a boost

[MirrorProfiles]

Considering a buffer pedal to go after my reamp box - needs to have a boost function (nothing ridiculous, but the cleaner the better. Doesn’t have to be a pedal format necessarily, if there is something with a beefy power supply and more headroom/less noise then I’m all for it.

Looking at Lehle Sunday Driver, 29 OAMP, Wampler Decibel +. But I really have no idea what’s out there or if there’s something obvious/decent ai should consider.

 

[James Freeman]

In my experience, FET based buffers create harmonics even when operating in the linear range ala BOSS pedals, so I prefer op-amp based buffers for they are more transparent.
Also, you can run opamp based buffers with a 12v or 18v power supply to get ±6v or ±9 peak rail voltage, that's +14.7dBu or +18.3dBu of clean headroom, and with a standard 9v power you get ±4.5v rails which is +12.3dBu.

Regarding boost, it is problematic, boosts often clip with input signal lower than the ± rail voltage, so you will probably have LESS true headroom than using the reamp box alone, but you might have a louder distorted signal which I assume is not what you want.

MOSKY Pure Buffer is the purest form of op-amp based buffer, it's a clone of the JHS Little Black Buffer.

 

[MirrorProfiles]

Hmm, yeah I’m not unhappy with my reamp level - can comfortably have things set up for 12dBu. I just wondered if I can get around 9dB more to play with and then I have a bit more wiggle room on the input side of things.

Mosky seems a good shout, will take a look. Even if I just continue to use my reamp chain as is, I wouldn’t mind having a buffer around just in case

 

[James Freeman]

Did you try to use a DI Box in reverse with a 25k volume pedal after it?
I can easily get a voltage at the output (input of DI box) that electrocutes me when I touch the cable with my fingers, with a 60Hz sine tone form the audio interface.

The audio interface can output like 4v (+15dBu) and the DI transformers typically have 10:1 turn ratio, I get a SHOCKING (literally) 40v at the output.
Don't feed that into any electronics without a volume box after the DI Box.

 

[MirrorProfiles]

Did you try to use a DI Box in reverse with a 25k volume pedal after it?
I can easily get a voltage at the output (input of DI box) that electrocutes me when I touch the cable with my fingers, with a 60Hz sine tone form the audio interface.

The audio interface can output like 4v (+15dBu) and the DI transformers typically have 10:1 turn ratio, I get a SHOCKING (literally) 40v at the output.
Don't feed that into any electronics without a volume box after the DI Box.

Ha I’ve sold off my other DI boxes but maybe I should try this route…

 

[James Freeman]

High Voltage!
Bruh.... 43v

Yeah, my audio interface is like +15dBu at the outputs and the passive DI box has standard 10:1 turn ratio transformer.
400Hz sine at 0dBFS form my DAW.

I've been reamping like that with the 25k volume box with great results, and I can calibrate to any dBu as you can see.

 

[James Freeman]

I should mention that a typical line outputs from audio interfaces have very low output impedance, like 100 to 300 ohm.
The impedance ratio of the DI Box is 100:1 (turn ratio squared), so you get between 10k to 30k output impedance after the DI Box, that's right about the range of passive guitar pickups output impedance.
Actually, now that I think about it, I need a higher impedance volume box, probably in the 250k-1Meg range, like a typical electric guitar volume pot value.

EDIT:
Yep, I confirm, with the 25k volume box I get 20v at full volume so the output impedance after the DI Box is around 20k+.
With a 500k volume box I get the original 40vAC at full volume, so use a high impedance volume box or pedal after the DI Box.
That should have been obvious to me, we convert low impedance back to high impedance when using the DI Box in reverse.

 

[MirrorProfiles]

what’s the downsides vs having a reamp box with a customised transformer ratio? presumably it would be less hassle than having to make different transformers?

or is it just less juggling around afterwards to get things where you need?

 

[James Freeman]

I don't think there is any difference at all between passive reamp boxes and DI Boxes in reverse except the lower ratio transformer in the reamp box.
Reamp boxes use 1:1 to 4:1 transformers from what I gather on google, and DI Boxes are typically 10:1 to 12:1.

It's a matter of output voltage and impedance, nothing more.
You probably don't want 40v to fry your electronics and lower output impedance is always better, so 10:1 is overkill for reamping and WILL damage equipment.

Yes, less juggling if you have "correct" level and impedance form the get go, most people adjust reamp boxes by ear and know fuck all about dBu or Impedance.

Sources:
https://www.diyrecordingequipment.c...y-how-the-line2amp-reamping-box-works-and-why
https://gearspace.com/board/showpost.php?p=9255480&postcount=15


EDIT:
BTW, "Touch Voltage" should not exceed 50vAC according to regulations, 35v is already quite uncomfortable.
An audio interface can output +18dBu (6v AC) through a 12:1 DI Box is 72v AC, that's almost mains.

 

[MirrorProfiles]

An audio interface can output +18dBu (6v AC) through a 12:1 DI Box is 72v AC, that's almost mains.

My monitor outs have up to 24dBu… sort of wish all my D/A had that much juice

 

[TubeStack]

Fulltone 2B has had my interest as a buffer + boost, but I haven't tried it yet.