The measured attenuation (at 1 kHz) was 11.5 dB - 2 dB more than predicted by the turns ratio. I measured the frequency response with line levels (+4 dBu) and got 15 Hz to 20 kHz +/- 2dB. I based my design on the Jensen AS092 schematic - my updated schematic is attached. So, not the greatest low end, but it is rated at 135 mW and we're going to be using it at line level so we can expect much better low frequency response. The frequency response of the 145R is rated at 150 Hz to 15 kHz (+/- 1 db, reference 1000 Hz). This can be achieved by adjusting the input level to the reamp box and / or using a level control on the reamp box. The 145R will give around 20*log10(1/3) = -9.5 dB attenuation, so we'll need an additional 12 dB of level reduction to match +4 dBu to a typical guitar level. (The Hammond 145R is available from a number of on-line sources including Mouser and Digikey. What is critical is to correctly load the secondary of the transformer. Then out of the reamp box to the instrument in of the AX8 with a standard guitar cable, then Out1 XLR from the AX8 to the XLR in of the sound card. We just need to attenuate the output level somehow.ĭigging around in my transformer "junk box", I found a Hammond 145R - 20k primary to 2K secondary (a turns ratio of around 3:1). If you can, you need to go XLR out from the sound card to XLR in of a reamp box such as Radial x-amp. Going without, as others have mentioned, causes a lot of unusable noise and everything just sounds worse. You should definitely get a dedicated re-amp box. Having A/Bd both on my personal setup, Id say yes. My conclusion: the transformer turns ratio isn't that critical. a reamping box is nothing else really but a 'backwards' DI box with the correct specs to match level and impedance. Other designs (e.g., the popular "New York Dave" design) use a 4:1 step-down transformer. Some designs use a direct box step-up transformer (the original reamp box did this, using a 1:7 transformer with input attenuation) while other designs use a 1:1 transformer (the Jensen design shown in application note AS092.pdf does this). It also needs isolation on the output to avoid ground loops. Output level: ideally the same as your guitar - around 100 mV RMS or -18 dBu (unbalanced) - this can vary quite a bit depending on your pickupsįrequency response: For guitar - 69 Hz (drop C#) to 10 kHz or so (for bass we'd need to go down to 30 Hz) Input level: typical line level from a mixer or audio interface - +4 dBu (balanced) It worked out much better than expected so I'm sharing my design in the hope that others will find it useful.Ī quick survey of reamp box designs led me to the follow requirements: I didn't have a reamp box so I decided to build one. (There's a good video on YouTube by Pete Thorn showing this.) All you need is a decent audio interface, a mic (or two) and a reamp box. After some digging, I found that you don't need the Tonex Capture. I recently got a Tonex pedal and wanted to capture a couple of the tube amps I've made.
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