tvrgeek
Major Contributor
Being an old QE, reading through this was fun and seeing the openness of Buckeye is refreshing.
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Buckeye Hypex Nc502mp Multichannel Amp Teardown
- Thread starter amirm
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I wonder if a wave washer would suffice the "gas tight" requirement.
tvrgeek
Major Contributor
If on the other side, maybe. We used stacks of them as springs to mount TO-3 transistors. But for a lug to chassis, no need. Lug to a board, then maybe an advantage as boards cold flow. The most reliable connections to solder on a lug/pigtail so it could mount to the chassis with a proper hardware stacked torqued. For an amplifier, I would pigtail-star them.
Even the TO-3 transistors, we soldered a lug to the board that sat on the transistor top flange with the spring stack. That way the current path was not through the hardware, but lug to board. I hate TO-3 and worse TO-66. Glad to see TO-3P and 220 packages!
Some of this may seem over complicated, but when people spend hundreds of thousands on computers and down time costs thousands a minute, it matters.
I also learned form my old British car experiences, to use dielectric grease in the fast-ons. The actual connections are from microscopic points and punch through, but the grease keeps it air/moisture tight. Basically, fast-ons are not the best, but they serve a purpose so using them to the best is OK.
As far as crimps, a proper AMP ratchet crimper with the correct die forms a fine crimp. To go further, the hydraulic mil-spec type can actually form a cold weld. Ever see one with two tiny round dots in the insulation? That is one. Quality of the lug counts. Some are basically crap with the brass alloy to week to hold up the pressure. The Hot/glue/heat shrink are very good and some even have a low temp solder that bonds at the same time. Price does go up a bunch and for a protected environment, overkill. For cars and boats, they are worth it.
Making my brain hurt. It was 30 years ago when I was in the lab!
Even the TO-3 transistors, we soldered a lug to the board that sat on the transistor top flange with the spring stack. That way the current path was not through the hardware, but lug to board. I hate TO-3 and worse TO-66. Glad to see TO-3P and 220 packages!
Some of this may seem over complicated, but when people spend hundreds of thousands on computers and down time costs thousands a minute, it matters.
I also learned form my old British car experiences, to use dielectric grease in the fast-ons. The actual connections are from microscopic points and punch through, but the grease keeps it air/moisture tight. Basically, fast-ons are not the best, but they serve a purpose so using them to the best is OK.
As far as crimps, a proper AMP ratchet crimper with the correct die forms a fine crimp. To go further, the hydraulic mil-spec type can actually form a cold weld. Ever see one with two tiny round dots in the insulation? That is one. Quality of the lug counts. Some are basically crap with the brass alloy to week to hold up the pressure. The Hot/glue/heat shrink are very good and some even have a low temp solder that bonds at the same time. Price does go up a bunch and for a protected environment, overkill. For cars and boats, they are worth it.
Making my brain hurt. It was 30 years ago when I was in the lab!
What I did (am doing) in my current build:
freeDSP Aurora-based USB 8-channel DSP/DAC/Preamp/Amp Build (in progress)
Build thread for my Aurora-based (almost) "everything" box. This will contain, at the very least, the following devices: - freeDSP Aurora - Mean Well RPS-30-7.5 - (2x) TPA3255EVM - (TBD) (2x) JLE TICore260BTL - Connex SMPS800RS The intended use is for the Aurora to act as a USB sound card in...
audiosciencereview.com
I don't have all the photos to show right now, but the ground bolt stackup goes like this, from outside to inside:
Step 1: Mechanically & electrically bonding the screw to the enclosure
- Serrated-flange cap screw - digs into the aluminum for a gas-tight connection
- Aluminum sheet metal enclosure
- Heavy-duty Belleville washer - maintains compressive pre-load in the bolted joint to make sure the cap screw never opens up or loosens
- Big fat nut to fully support the extra-wide OD of the Belleville washer. Ended up using a strut channel nut since I had one.
Step 2: Connecting stuff
- High-strength hex nut
- Crimped PIDG ring terminal
- (hidden in photo, sandiwched between a hex nut and a ring terminal) a Belleville washer with serrated faces - provides extra long-term preload and thread locking, and also cuts through oxides on both sides to improve electrical conductivity (the ring terminal has to conduct through the hex nut(s) before reaching the grounded bolt/enclosure)
- High-strength hex nut
I did a test joint with the smaller Belleville washers next to the ring terminals and found that the hex nut faces did get scraped clean, so I'm quite confident the electrons will go where they need to.
tvrgeek
Major Contributor
One of the reasons we blocked star washers is the serrations could dislodge fragments of metal which was not nice floating around on circuit boards. That they did not work was the major reason. Split locks were just as bad. Bevel washers are great when there is considerable thermal expansion and contraction. Transistor flange to heat sink for example. I am glad to see most transistors are mounted with spring clips now and TO-3 style packages are not as common.
Back in the olden days, we used glypt.
Back in the olden days, we used glypt.
I have seen a lot of these used in industrial automation panels/racks, as well:
Hi folks,
I recently became a member of the Buckeye amp family, having ordered a 4 channel nc252mp based amp and a 4 channel NC502MP based amp. In a 7.1.4 system the stronger 502 amp is for side and rears and the 252 amp is for my Atmos channels.
Long story short, when I hook up the amp with 2 nc252mp modules to my bed layer speakers they’re super quiet and all that’s heard is the amp. Basically it sounds amazing and perfect. But when I hook up my amp with the 2 nc502mp modules there‘s immediately very loud noise coming from the speakers they’re hooked up to. Unfortunately I can’t up a video with the noises but it sounds like electrical interference mixed with high pitched noises and such. It’s very distracting! Futhermore the sounds ONLY come on when sides and/or rear speakers are hooked up and it doesn’t go away regardless if I have the xlr cables connected or not? My side and rear speakers are JTR Noesis 110HT‘s btw.
Is there any kind of a fix to this noise from the nc502mp amp? I’m assuming it had to do with the distance to my side and rear speakers (~20 feet away) since none of my LCRs have the sound when connected to that amp. I figured I’d ask before returning the amp for a refund. I’ve posted this question on the other Buckeye amp thread as someone may have a simple solution I haven’t thought of.
TIA
-John
I recently became a member of the Buckeye amp family, having ordered a 4 channel nc252mp based amp and a 4 channel NC502MP based amp. In a 7.1.4 system the stronger 502 amp is for side and rears and the 252 amp is for my Atmos channels.
Long story short, when I hook up the amp with 2 nc252mp modules to my bed layer speakers they’re super quiet and all that’s heard is the amp. Basically it sounds amazing and perfect. But when I hook up my amp with the 2 nc502mp modules there‘s immediately very loud noise coming from the speakers they’re hooked up to. Unfortunately I can’t up a video with the noises but it sounds like electrical interference mixed with high pitched noises and such. It’s very distracting! Futhermore the sounds ONLY come on when sides and/or rear speakers are hooked up and it doesn’t go away regardless if I have the xlr cables connected or not? My side and rear speakers are JTR Noesis 110HT‘s btw.
Is there any kind of a fix to this noise from the nc502mp amp? I’m assuming it had to do with the distance to my side and rear speakers (~20 feet away) since none of my LCRs have the sound when connected to that amp. I figured I’d ask before returning the amp for a refund. I’ve posted this question on the other Buckeye amp thread as someone may have a simple solution I haven’t thought of.
TIA
-John
Does it do it no matter the channels the surrounds are hooked up to?
Also if you switch inputs, like put the front left/right Input on the surround channels, does it do it?
Yes, it did it no matter which channel is hooked up nor input. Fortunately there haven’t been any noise related issues since I went all nc252mp modules. I just saw your question today.
ItSoundsNatural01
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Long story short, no one could figure out what was causing the noises. But thankfully Buckeye amp issued a full refund for the faulty amp. Out of curiosity, and really wanting to try the nc502mp modules, I decided to order a VTV amp with the same modules in a Ghent case. I figured, hey if the noise is still present even with a VTV maybe my speakers or some other part of my system just refuses to play nice with nc502mp modules (but not nc252mp’s strangely enough). Upon receiving the amp I was pleased to see a full amp testing by audio precision. The VTV amp itself has worked without any issues, I’m more than happy with the audio performance the nc502mp’s give.
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Yea still no idea what the issue was. I sold that amp to a customer after it was returned and it works perfectly fine for them 
I’m actually glad the amp worked well for some else and it’s a happy ending after all. To this day I still don’t understand why it didn’t work in my system and consider it just a fluke. I run and love my Buckeye amp w/ nc252mp modules for Atmos duty, I still wouldn’t hesitate to recommend the brand to anyone!Yea still no idea what the issue was. I sold that amp to a customer after it was returned and it works perfectly fine for them
Nice amp! I've bought some hypex modules too. It appears that in this amp the XLR pin 1 is connected to the pcb grounds.Yea still no idea what the issue was. I sold that amp to a customer after it was returned and it works perfectly fine for them
After reading the white paper on the Hypex site: Dealing with legacy pin 1 problems, I was going to connect them to the eathed chassis.
Is Hypex right, the paper seemed to make a lot of sense, or is it better to use signal ground as in the Buckeye?
Maybe that is the reason for some people having groundloops, despite using differential XLRs.
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I connect Pin 1 to the chassis ground on all my amp builds (even the Ghents). Then the ground wire for the Hypex module (PCB) is connected to the chassis ground as well, near the Pin 1 grounding point.
Actually on my builds you can see the Neutrik connectors have a spade tab. The Hypex module (PCB) ground attaches to this tab while the Pin 1 wire attaches to one of the XLR mounting screws. So both are connected through the XLR body/chassis ground, per Hypex recommendations.
Thanks!
Count Dacula
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In automotive DC applications, pulling a ground off different points of the chassis can result in a voltage differential across sub component systems.
TheWalkman
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I ended up going with the Audiophonics HPA-S400 (Purifi) in June, 2022 and couldn’t be happier: this is my endgame amp.
After much searching and buckets of cash, I have finally attained Audio Nirvana and can now focus my energies on listening to the music I love and not chasing the elusive, sound of, “a magical wire that amplifies perfectly” that I have chased for decades.
(If only I could bring back the decades old, high frequency response of a pair well worn ears that have served me well!)
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