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Post by bikescene on Feb 1, 2024 9:30:59 GMT -6
I finally put together my Hairball FET500 Rev D kit that I bought from Black Friday. Sorting the resistors was the main source of my procrastination, but I was motivated to get the kit built by the end of January. The directions on the Hairball site were fine, and the visual build map made it easy to populate the PCBs. Mechanically, the assembly lined up with minimal issues.  I just calibrated the unit before I had to go to work. The trim pot for gain reduction metering is a 20 turn pot. I didn’t realize at first (or forgot) and thought the adjustment range was within 1 revolution. Otherwise, Hairball’s online directions and YouTube calibration tutorial were easy to follow along to. I didn’t do the THD calibration step, and am not sure I have the patience to figure out how to. I only got to play with it briefly on a snare track for a few minutes and only on the 20:1 ratio that was used for calibration. Not enough time to discern the nuances of the sound, but enough for instant gratification. I’m looking forward to comparing the FET500 to the other 1176-ish plugs I have (UAD, Softube FET, IK, PSP FETpressor). |
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Post by ironinthepath on Feb 2, 2024 8:09:21 GMT -6
Awesome! I bought a stereo matched Rev D 500 kit during the lockdown era of pandemic but never actually built it…
This is motivation!
Would love to hear your thoughts on the sonics too.
-Chris
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Post by ragan on Feb 3, 2024 13:31:05 GMT -6
I built a Rev A. I sold it when I got the Stam ADG but it was cool. Might build another one someday.
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Post by okcrecording on Feb 3, 2024 14:31:13 GMT -6
Fantastic bike. I have one of these I need to build myself.
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Post by bikescene on Feb 4, 2024 13:39:06 GMT -6
Awesome! I bought a stereo matched Rev D 500 kit during the lockdown era of pandemic but never actually built it… This is motivation! Would love to hear your thoughts on the sonics too. -Chris The build is pretty quick after stuffing the resistors. Some of the components are close together, but nothing as bad as a 2520 op amp. Calibration is much easier with a 500 series extender when you decide to build your kits. The gain reduction trim pot is on the main PCB, accessed through a hole on the meter PCB. Reaching through the side of a 500 series chassis to make this adjustment is kind of annoying, although not impossible. I’ve been evaluating the sound on drums at low and high ratios. My first inclination was to use the 20:1 and slam modes to crush drums, which was fun. Lower ratios like 4:1 and 2:1 sound nice for less aggressive transient control. The knobs are small, so I’m not making fine resolution turns. Though having a physical control for the release is a revelation, especially when crushing drums. It just feels better to react to a sound by twisting knobs, rather than trying to discern if a 0.1 change on a plug-in knob matters. I haven’t compared to plugins yet. The module does run very warm, so it will be interesting to see how it holds up over time. |
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Post by ironinthepath on Feb 4, 2024 14:20:23 GMT -6
Any thoughts on whether the Rev D 500 has a "sound" on its own before compressing (without any gain reduction)?
I assume it will and it's in the ballpark of most 1176-style compressors, the key difference for me is not knowing about the Ed Anderson transformers (and I haven't yet looked to see how different, if at all, the Rev D 500 units are compared to the full 19 inch rack Rev D transformers used by Hairball). Thanks!
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Post by bikescene on Feb 4, 2024 16:34:29 GMT -6
Any thoughts on whether the Rev D 500 has a "sound" on its own before compressing (without any gain reduction)? I assume it will and it's in the ballpark of most 1176-style compressors, the key difference for me is not knowing about the Ed Anderson transformers (and I haven't yet looked to see how different, if at all, the Rev D 500 units are compared to the full 19 inch rack Rev D transformers used by Hairball). Thanks! I’ll try to run some audio through it some time this week, and will see if it’ll be any use. I took a peak at the FET Rack build guide. It looks like the input (C-3837-1) and output (EA-5002) transformers are identical. Transistors, trim pots, and many capacitors look to be the same. The heat sink for the 2N3053 looks like it’s more beefy in the rack, and that part gets hot. The FET500 has to use low profile radial electrolytic caps throughout out of necessity. Completely different metering circuitry though. Not sure who builds the EA-5002 now. It sounds like it used to be built by Magnetic Components prior to 2021 from this thread: groupdiy.com/threads/calling-ed-anderson.77475/#post-989976 |
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Post by ironinthepath on Feb 4, 2024 20:32:44 GMT -6
A friend of mine LOVES his 19 inch hairball rev D, and if there is no compromise in the transformers I’d guess there’s a pretty good chance that the differences mentioned won’t be too detrimental. I need to solder mine up!
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kcatthedog
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Post by kcatthedog on Feb 5, 2024 2:02:15 GMT -6
I wasn’t aware there were YT calibration videos. i had some trouble my A a while back ( could’ve been older eyes reading resister values) and sent it in which added to the cost.
Great that the 500 worked out for you!
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Post by audiospecific on Feb 5, 2024 16:15:46 GMT -6
its just a 600 ohm iron output transformer. But that edcor XS4400 I've been working with would work as well as the 600 ohm 1:1 that Jensen made for the API modules.
The input transformer is not difficult either. That is an iron core transformer that was undersized (1/8 W) accidentally on purpose.
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Post by matt@IAA on Feb 6, 2024 9:44:57 GMT -6
I took a peak at the FET Rack build guide. It looks like the input (C-3837-1) and output (EA-5002) transformers are identical. Transistors, trim pots, and many capacitors look to be the same. The heat sink for the 2N3053 looks like it’s more beefy in the rack, and that part gets hot. The FET500 has to use low profile radial electrolytic caps throughout out of necessity. Completely different metering circuitry though. Not sure who builds the EA-5002 now. It sounds like it used to be built by Magnetic Components prior to 2021 from this thread: groupdiy.com/threads/calling-ed-anderson.77475/#post-989976For the avoidance of confusion - the output transformer used in an 1176 is not a standard 1:1 600 ohm transformer. The design uses several different feedback paths through the transformer. Cinemag makes a UA-5002 under their part number CM-96731. No idea if it will fit in a Hairball PCB or 500 series in general. Here's the Cinemag data sheet cinemag.biz/output/PDF/CM-96731.pdf |
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Post by ironinthepath on Feb 6, 2024 10:11:16 GMT -6
I agree with Matt, it's also clear when looking at the original schematic from MNAT: mnats.net/files/FET-D500.pdf (see output transformer T2). Basically the same concept is used Universal Audio's 1108 mic pre: www225.pair.com/audio/waltzingbear/Schematics/Urei/UA_1108_and_man.pdf (schematic on last page of pdf) For a while I've meant to dig into the design and better understand the details of the magnetically coupled feedback path, haven't done that yet though. Have been considering making a DIY 1108 preamp in the process (and bought two of the original UA transformers, well the reissue, for the project). If I do it, I'll definitely report back. |
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Post by audiospecific on Feb 6, 2024 10:41:07 GMT -6
I took a peak at the FET Rack build guide. It looks like the input (C-3837-1) and output (EA-5002) transformers are identical. Transistors, trim pots, and many capacitors look to be the same. The heat sink for the 2N3053 looks like it’s more beefy in the rack, and that part gets hot. The FET500 has to use low profile radial electrolytic caps throughout out of necessity. Completely different metering circuitry though. Not sure who builds the EA-5002 now. It sounds like it used to be built by Magnetic Components prior to 2021 from this thread: groupdiy.com/threads/calling-ed-anderson.77475/#post-989976For the avoidance of confusion - the output transformer used in an 1176 is not a standard 1:1 600 ohm transformer. The design uses several different feedback paths through the transformer. Cinemag makes a UA-5002 under their part number CM-96731. No idea if it will fit in a Hairball PCB or 500 series in general. Here's the Cinemag data sheet cinemag.biz/output/PDF/CM-96731.pdfI'm still thinking its a 600 ohm quadfilar of some sort.
The output stage has been one of the design flaw areas they worked on and made revisions. Revesion F & G use a 300 ohm ct by 4 coils quadfilar. Which actually are the better (less noise) than the a &b models people are cloning.
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Post by matt@IAA on Feb 6, 2024 11:11:04 GMT -6
It isn’t quadrifilar - the UA5002 has five windings.
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Post by bikescene on Feb 6, 2024 13:12:44 GMT -6
I took a peak at the FET Rack build guide. It looks like the input (C-3837-1) and output (EA-5002) transformers are identical. Transistors, trim pots, and many capacitors look to be the same. The heat sink for the 2N3053 looks like it’s more beefy in the rack, and that part gets hot. The FET500 has to use low profile radial electrolytic caps throughout out of necessity. Completely different metering circuitry though. Not sure who builds the EA-5002 now. It sounds like it used to be built by Magnetic Components prior to 2021 from this thread: groupdiy.com/threads/calling-ed-anderson.77475/#post-989976For the avoidance of confusion - the output transformer used in an 1176 is not a standard 1:1 600 ohm transformer. The design uses several different feedback paths through the transformer. Cinemag makes a UA-5002 under their part number CM-96731. No idea if it will fit in a Hairball PCB or 500 series in general. Here's the Cinemag data sheet cinemag.biz/output/PDF/CM-96731.pdfI agree. What I meant was that the model numbers of the FET/500 transformers match those respective model numbers of the big FET Rack. Poor choice of words on my end. |
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Post by ironinthepath on Feb 6, 2024 13:42:19 GMT -6
"What I meant was that the model numbers of the FET/500 transformers match those respective model numbers of the big FET Rack" That's the main thing, thanks for that! -Chris |
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Post by bikescene on Feb 12, 2024 19:21:10 GMT -6
app.box.com/s/ljslu4qtib39z70e1jqmsu8eo781ovp0ironinthepath I ran a short snippet of audio through the FET500. One of the clips is the compressor with no gain reduction. The link to audio is above. I got sick and didn’t get a chance to run better audio through. I also ran through my other 500 series modules run flat to reference colors their circuits impart vs the FET500 with no GR. Five 48kHz short excerpts of mono drums 1 - bypassed sound on the FET500 2- FET500 No GR 4:1 Att 9:00 Rel 3:00 3 - FET500 9dB GR 4:1 Att 9:00 Rel 3:00 4 - CAPI VP28 Unity Gain 5 - DIYRE EQP5 w/ Vintage Option EQ Flat On another note, I couldn’t get UAD Rev E or Softube FET Comp Mk II to behave like the FET500 in the low end. LED vs VU metering was a very different experience. I was going to render the plugins to share, but then couldn’t reliably trust my hearing from congestion.
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