andrewsrea
Active member
As you can see from the pictures below, I have the Median Compressor populated and loaded in the enclosure for functional test. FYI: I am calling my build, the 'Spirit of 1776' - a little play on the UREI 1176 it borrows from. I had a few challenges so far:
- Reviewed the design, compared it to the UREI schematic and decided to build it stock, as it is a great design which could easily be used for bass and keys as well.
- I had accidentally selected VSSOP sized (smaller than a tick) OPA1678 IC's from Mouser, which they could not be used to the SOT-23 to SIP adapter I purchased from PedalPCB. I reordered SOT-23 size (checking the footprint specs to the adapter), which a dozen cost me $18 delivered vs. the $40 that (4) TSSOP / VSSOP adapters would have cost. I'll most likely throw away the VSSOP's, because it is unlikely I'll every have a use for them.
- For functional test, I've substituted TL072's for the OPA1678. As others have stated with their builds, you could definitely use TL072 and not spend the time and money on the OPA1678. I will be using the OPA's which I expect would have an ever-lower noise floor and transparent sound, however the TL072's had no noticeable noise floor, even with the 'Compress' (threshold) on full. The tone from them was nice and accurate.
- Surface mount MMBF5457 was my first attempt at the surface mounted FETS, which was a failure as I do not have a convenient way of auditioning and matching them. Therefore, they were never close to the targets. Luckily, I considered this might happen and had already socketed for T0-92 2N5457, which claimed to be NOS Fairchild components I bought from PedalPCB.
- Found a matched pair of these 2N5457 Fairchilds and got close to the schematic specs (Vgs = 1.43 for Q1) and found that setting resulted in symmetrical compression of a 1kHz sine wave on an oscilloscope.
To be honest, guitar compression as an effect has rarely been my thing (pumping & breathing, squishy tone, etc) and I have lots of experience with studio compressors (mostly subtle effects), which are used as gentile ways of getting an instrument or vocal to sit in a mix. That said, I really like this pedal compressor over a Ross, MXR (VCA type) or a DoD 260 (opto-resistor type). My favorite setting so far is the Compress at 8:30, Attack at 9:00, Release at 8:30, Blend at 3:00, Tone at 11:00 and Volume at 2:00ish.
Ready for paint and marking!
- Reviewed the design, compared it to the UREI schematic and decided to build it stock, as it is a great design which could easily be used for bass and keys as well.
- I had accidentally selected VSSOP sized (smaller than a tick) OPA1678 IC's from Mouser, which they could not be used to the SOT-23 to SIP adapter I purchased from PedalPCB. I reordered SOT-23 size (checking the footprint specs to the adapter), which a dozen cost me $18 delivered vs. the $40 that (4) TSSOP / VSSOP adapters would have cost. I'll most likely throw away the VSSOP's, because it is unlikely I'll every have a use for them.
- For functional test, I've substituted TL072's for the OPA1678. As others have stated with their builds, you could definitely use TL072 and not spend the time and money on the OPA1678. I will be using the OPA's which I expect would have an ever-lower noise floor and transparent sound, however the TL072's had no noticeable noise floor, even with the 'Compress' (threshold) on full. The tone from them was nice and accurate.
- Surface mount MMBF5457 was my first attempt at the surface mounted FETS, which was a failure as I do not have a convenient way of auditioning and matching them. Therefore, they were never close to the targets. Luckily, I considered this might happen and had already socketed for T0-92 2N5457, which claimed to be NOS Fairchild components I bought from PedalPCB.
- Found a matched pair of these 2N5457 Fairchilds and got close to the schematic specs (Vgs = 1.43 for Q1) and found that setting resulted in symmetrical compression of a 1kHz sine wave on an oscilloscope.
To be honest, guitar compression as an effect has rarely been my thing (pumping & breathing, squishy tone, etc) and I have lots of experience with studio compressors (mostly subtle effects), which are used as gentile ways of getting an instrument or vocal to sit in a mix. That said, I really like this pedal compressor over a Ross, MXR (VCA type) or a DoD 260 (opto-resistor type). My favorite setting so far is the Compress at 8:30, Attack at 9:00, Release at 8:30, Blend at 3:00, Tone at 11:00 and Volume at 2:00ish.
Ready for paint and marking!
