No build guide other than this thread. Nothing needs to be raised off the board if you use the specified 5W KOA BPR non inductive vertical power resistors.
Good luck with your build. It’s a straightforward amp to assemble. Soldering the big inductor on will take a big iron. Preheating the board with a hot air tool will help to slow the solder.
Good luck with your build. It’s a straightforward amp to assemble. Soldering the big inductor on will take a big iron. Preheating the board with a hot air tool will help to slow the solder.
Thanks,
I did try and solder the inductor with a 5mm spade bit on a weller station, successfulish, now waiting on another 5mm bit to attack it with an iron on both sides! On the inductor I take it that the larger rectangle pins are for mounting only?
I did try and solder the inductor with a 5mm spade bit on a weller station, successfulish, now waiting on another 5mm bit to attack it with an iron on both sides! On the inductor I take it that the larger rectangle pins are for mounting only?
It’s been a while but I don’t recall extra mounting tabs in the inductor. The flat copper wire was so substantial. But if there are more than 2 solder contacts then the two not connected are extra.
If you look at the layout the two big rectangular slots are the main connections for the Wurth inductor. The smaller pins ones are for home wound round wire inductors (18-16ga 12-15 turns around 0.5in mandrel).
2 of the holes are not connected and for stabilization of wire wound shielded inductor.
If you look at the layout the two big rectangular slots are the main connections for the Wurth inductor. The smaller pins ones are for home wound round wire inductors (18-16ga 12-15 turns around 0.5in mandrel).
2 of the holes are not connected and for stabilization of wire wound shielded inductor.
Pretty much assembled the boards now just sorting the molex sockets from the premium bom, just to check the fly wires to the Fets I take it 18awg is OK as that's the limit on the pins linked for the Molex connectors?
Also what wire size for the connector going to V123?
Also what wire size for the connector going to V123?
18ga silicone jacket high strand count RC battery wires is what I use.
Double check to make sure you have correct pins on wires. And correct N or P MOSFET installed.
V123 is the temperature compensation transistor. Only small gauge needed. I typically use 28ga silicone wire.
The griddle amp thread has some nice pictures of the FH9HVX build in case you haven’t seen it. Here is how I mounted the MOSFETs and the tempcomp.
Double check to make sure you have correct pins on wires. And correct N or P MOSFET installed.
V123 is the temperature compensation transistor. Only small gauge needed. I typically use 28ga silicone wire.
The griddle amp thread has some nice pictures of the FH9HVX build in case you haven’t seen it. Here is how I mounted the MOSFETs and the tempcomp.
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Perfect thanks I've ordered some.
That's what I'm building a 'griddle' amp, just wondering looking at your pictures why are you doubling up on the ground wires?
That's what I'm building a 'griddle' amp, just wondering looking at your pictures why are you doubling up on the ground wires?
Trying to reduce impedance to chassis ground to reduce EMI noise. Probably not necessary.
Glad someone else is building a griddle amp. It sure is unique. One of my favorite amps because nothing else like it.
Glad someone else is building a griddle amp. It sure is unique. One of my favorite amps because nothing else like it.
Chrisr3521,
I skipped the crimping part for the flying leads with something like this off the shelf part - you can consider this if you already haven't ordered the crimping tools:
https://www.amazon.com/ZLKSKER-Extension-Desktop-Computer-Connector/dp/B08R36YKPB
Keep the male part and connect the wires on the opposite end to your MOSFETs; there are 4 wires, so you need to cut off the one. And for the remaining 3 wires, you will be left with 2 wires with the same color - so put some different color heat-shrink tubing on it so that you have the MOSFET pins connected properly.
I skipped the crimping part for the flying leads with something like this off the shelf part - you can consider this if you already haven't ordered the crimping tools:
https://www.amazon.com/ZLKSKER-Extension-Desktop-Computer-Connector/dp/B08R36YKPB
Keep the male part and connect the wires on the opposite end to your MOSFETs; there are 4 wires, so you need to cut off the one. And for the remaining 3 wires, you will be left with 2 wires with the same color - so put some different color heat-shrink tubing on it so that you have the MOSFET pins connected properly.
I’m lucky enough to know Anand (Poseidon’s Voice) and have had the opportunity to hear a number of his creations in my system/room. I’ve long admired his knowledge of and passion for DIY audio, along with his commitment to build the highest quality DIY components.
On one of his visits, he hooked up one of his amps and sat down in the sweet spot, while I sat off to the side to listen. One of the tunes played was a Lyle Lovett song (I can’t definitively remember which one) and even though I was well outside the sweet spot, it hit me how much humanity and emotion the vocals were exhibiting. I mentioned this to Anand, but didn’t even think to ask what amp it was at the time. It definitely stuck with me though.
Fast forward a few months and my thoughts about that amp just surfaced out of nowhere. I reached out to Anand to find out which amp it was - it was his FH9HVX build. In a spontaneous fit, I asked him if he would build me one. His response was more than I could ask - he would sell me his build! For the last several months, I’ve been the proud new owner of Anand’s FH9HVX.
I’m mostly an objective audiophile these days and think differences in well designed amps are likely very small. Having said that, for some reason, I just really enjoy listening to this amp. I swap other objectively great amps in and out, but always end up with the FH9HVX as my favorite. I think it’s ever so slightly rounder and warmer than other amps I have on hand. To me, this makes instruments and voices sound more natural and less mechanical. It has plenty of clarity and detail, and is dead quiet, but those attributes aren’t thrust at you or glaringly obvious. To me, it’s a smartly balanced combination of all the things we audionuts are looking for.
Combine those attributes with Anand’s over-the-top build and you have a great package. I’m happy to be the owner of this great design and unique piece!
(Edit for missing ‘and’)
On one of his visits, he hooked up one of his amps and sat down in the sweet spot, while I sat off to the side to listen. One of the tunes played was a Lyle Lovett song (I can’t definitively remember which one) and even though I was well outside the sweet spot, it hit me how much humanity and emotion the vocals were exhibiting. I mentioned this to Anand, but didn’t even think to ask what amp it was at the time. It definitely stuck with me though.
Fast forward a few months and my thoughts about that amp just surfaced out of nowhere. I reached out to Anand to find out which amp it was - it was his FH9HVX build. In a spontaneous fit, I asked him if he would build me one. His response was more than I could ask - he would sell me his build! For the last several months, I’ve been the proud new owner of Anand’s FH9HVX.
I’m mostly an objective audiophile these days and think differences in well designed amps are likely very small. Having said that, for some reason, I just really enjoy listening to this amp. I swap other objectively great amps in and out, but always end up with the FH9HVX as my favorite. I think it’s ever so slightly rounder and warmer than other amps I have on hand. To me, this makes instruments and voices sound more natural and less mechanical. It has plenty of clarity and detail, and is dead quiet, but those attributes aren’t thrust at you or glaringly obvious. To me, it’s a smartly balanced combination of all the things we audionuts are looking for.
Combine those attributes with Anand’s over-the-top build and you have a great package. I’m happy to be the owner of this great design and unique piece!
(Edit for missing ‘and’)
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groovybassist,
Thanks for sharing your impressions.
What speakers are you using with the FH9HVX?
Thanks for sharing your impressions.
What speakers are you using with the FH9HVX?
I have two different speakers I’ve used the FH9HVX with - Philharmonic Audio HT Towers and Ascend Acoustics Sierra LXs.
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Thanks for sharing your adventures with the FH9HVX, @groovybassist !
I have always said that if I could only have one amp to do it all for the rest of my life, the FH9HVX would be not be a bad amp to have.
Anand’s superb build must be amazing to have in your audio rack.
Enjoy!
I have always said that if I could only have one amp to do it all for the rest of my life, the FH9HVX would be not be a bad amp to have.
Anand’s superb build must be amazing to have in your audio rack.
Enjoy!
I'm working on the layout of my amp, it's going in a hidden area so I'm just going to build it on a 12 inch by 12 inch aluminum plate, kind of like the griddle amps. A question I have to answer is how to orient the transformer - horizontally or vertically.
Horizontal should allow me to fit on the plate with no problem.
But vertically would allow a bit more room and potentially orient any stray flux away from the PCBs.
Opinions?
Horizontal should allow me to fit on the plate with no problem.
But vertically would allow a bit more room and potentially orient any stray flux away from the PCBs.
Opinions?
Did I break this thread? No comments for 3 weeks!
Anyway I went with the horizontal transformer orientation. I have 1 channel finished, it checked out perfectly. Dead silent with the input shorted, I actually thought something was disconnected at first. I'm now away on vacation for the next 3 weeks, when I return I'll finish and post pictures and measurements.
Anyway I went with the horizontal transformer orientation. I have 1 channel finished, it checked out perfectly. Dead silent with the input shorted, I actually thought something was disconnected at first. I'm now away on vacation for the next 3 weeks, when I return I'll finish and post pictures and measurements.
Strange, but I didn’t get a notification on this or must have missed it. Regarding orientation, it depends on the overall system and layout. But I often use horizontal because it is the easiest to implement. Glad that it worked out being quiet for you. What is important is to keep the input signal wires far away from the trafo.
IT IS ALIVE!!!
The first tests went very well, no audible noise at all with the inputs shorted. I painstakingly matched the input transistors so there's less than 1 mV offset on both sides. I did a brief listen with my crappy test MP3 player and lab bench speakers and so far it sounds great.
Tomorrow I'll clean up some of the wiring as well as the bench and do a lot more testing for temperature and distortion. Plus sharp eyes will notice that there's no output protection at all so I'm going to be adding output fuses plus a relay to disconnect the speakers if one of the supply fuses blows. Hopefully that will be enough protection.
Time to head out for some dinner and live music... the Yardbirds in Sellersville PA.
But did I mention.... it's ALIVE!!!
The first tests went very well, no audible noise at all with the inputs shorted. I painstakingly matched the input transistors so there's less than 1 mV offset on both sides. I did a brief listen with my crappy test MP3 player and lab bench speakers and so far it sounds great.
Tomorrow I'll clean up some of the wiring as well as the bench and do a lot more testing for temperature and distortion. Plus sharp eyes will notice that there's no output protection at all so I'm going to be adding output fuses plus a relay to disconnect the speakers if one of the supply fuses blows. Hopefully that will be enough protection.
Time to head out for some dinner and live music... the Yardbirds in Sellersville PA.
But did I mention.... it's ALIVE!!!
I did some temperature testing, and the results weren't good. There's a much bigger temperature difference between the output FETs and the aluminum plate than I expected. At 10 watts out I was seeing the FETs hit almost 200 degrees F while the plate was barely above room temperature. Look how distinct the temperature line is from the backside of the FET to the plate instead of a gradual fade to ambient. It looks almost like there's no thermal conduction at all!
To the best of my ability to visually observe the plate looks flat and the FET is tight against it. My first suspect is the insulators I got from Amazon since I couldn't find any thermal data on them. So I ordered some silicone elastomer and mica insulators from Mouser to see how they perform.
To the best of my ability to visually observe the plate looks flat and the FET is tight against it. My first suspect is the insulators I got from Amazon since I couldn't find any thermal data on them. So I ordered some silicone elastomer and mica insulators from Mouser to see how they perform.