Questions about the GPDI/IRs SMPS Power Supply and Increased Preamp Plate Voltage

Stage & Studio Valvulator GPDI/IR
1

I’m interested in the Fryette GPDI/IR after falling in love with some of the Deliverance profiles available for Tonex. After watching some videos of Steve discussing the GPDI, I have two points of concern about the product:

  1. In this Youtube interview with Perfecto De Castro, Steve explains that a big con of class D amplifiers is that, though technically inaudible, there is a big negative impact to the feel of the sound due to use of high frequency filters that work via applying phase shifts to high frequency signal components. Would the GPDI power supply’s SMPS design require similar filtering, thus suffering from similar “feel” drawbacks? If that’s the case, would this be mitigated using only the GPDIs preamp with an external tube power amp, or does SMPS introduce similar high frequency issues at the preamp level?
    Reference: 1:34:00 to 1:43:00 of https://www.youtube.com/watch?v=orCUQDRV53g

  2. Steve talks about how that the headroom of the GPDI was improved by increasing the plate voltage of the preamp tubes to give an experience that is “more akin to the playing experience of our big amps”. Is it correct to say that this increase still doesn’t make the GPDIs headroom exactly rise to the levels of the Deliverance heads? I’m loving the headroom of the Deliverance 120 Tonex captures and would be hesitant to compromise if the GPDI has much lower headroom. How does the headroom of the Synergy Deliverance module compare?
    Reference: https://www.youtube.com/shorts/5WylBx0l9aw

Mostly concerned that I would buy the GPDI/IR or Deliverance module and that it wouldn’t give me the same responsiveness as profiles, even if combined with a girthier tube power amp.

Thanks,
Alex

2

Welcome to the forum Skeletor.

  1. The power supply does require filtering to eliminate EMI, but that does not happen at the output stage. That’s entirely isolated to the power supply function and does not impact the fidelity and responsiveness of the output stage.

  2. As explained in that video, the improved power supply in the GPDI duplicates the voltage levels present in the Deliverance amps. But that’s not the only reason the GPDI delivers a more satisfying playing experience. Check out that same video here: https://youtu.be/orCUQDRV53g?t=4891 where Steve discusses the “Flipbook analogy”. That’s something that even the slightly lower headroom first generation GPDI and Synergy modules excel atin terms of playing experience compared to whatever amp module or profile you are comparing them to.

Dave