Відео

You'll get the performance specified in the Purifi 1ET400A data sheet: purifi-audio.com/document/share/32/11348bfa-bc4c-4811-891e-ed4e1501ab94

Yeah... That would be a pretty logical extension of my product portfolio. It's been on my radar for quite a while now.

A feed-through terminator like the HP 10100C that I'm using in the video has the 50 Ω in parallel with the load. The load of the amplifier is 47 kΩ, so the 50 Ω terminator makes the generator 'see' 50 Ω.

Depends on your disposable income. Many build DIY amps...

Fluke 70-series or 80-series would be great. They're not that expensive used. Get one that's calibrated.

Because they'd want a really, really good amp.

I do take payments in CAD by eTransfer. That way both of us save a few percent. You can always contact me by email to set that up.

My Modulus-286 and Modulus-686 are all surface mount. As are several of my other circuits.

Have a look at the Modulus-286 and Modulus-686. They're fully assembled and all SMD. I'll have more Modulus-286 available in about a month.

Great suggestion. Thank you. Which tools should I assume the builder has access to for the oscillation video?

@@Neurochrome2010 From what I have learnt, DSO is a must. I tried to check chipamp oscillations on a DSO(not mine) but couldn't understand what to look for

I'll see if I can get something together. Thanks for the suggestion.

I bought the Purifi amp modules from Purifi and the SMPS1200 from Hypex. The input buffer and chassis I design and sell. Don't like XLR connectors? Just build it with RCA inputs.

@@Neurochrome2010 very nice. See I love doing this because I enjoy beautiful sound that reveals sound stage and depth.

I will at some point. I'm currently mulling over how to best approach that situation. The chassis are expensive, and I can't afford having too much money tied up in aluminum. I'm considering combining the Modulus Chassis with the Purifi Chassis. Another option could be to have a dedicated Purifi chassis but add support for the newer amp modules as well. Decisions, decisions.

@@Neurochrome2010 yeah I did notice that they are very similar.

Yep. The only drawback of a 'universal' chassis is that it would have a lot of holes in the bottom panel and many of these holes would go unused. That could cause confusion.

@@Neurochrome2010 maybe you could label them like set a and b or something

If I wanted to go completely crazy (and pay extra) I could just have a legend printed on the inside of the bottom panel. Though, a page in the documentation could do the same trick. I'm sure I can find a good solution. Anyway. If you sign up for my newsletter (neurochrome.com/newsletter) you'll be the first to know about a new chassis.

The HP 6237 is hard to beat.

Sounds like a dead relay. It's pretty common that relay contacts oxidize. You might be able to salvage it if you can open the relay and polish up the switch points. The DeoxIT I use in the video should work on that.

@@Neurochrome2010 I have some deoxit D5. Friend of mine and I swear by the stuff. Adrian Black keeps some in a needle dropper bottle. I've been meaning to do the same. Absolutely will try it on that relay. Been meaning to. Just my PC sits on top of the receiver and unhooking everything is a nightmare. Been a backburner thing. Its front panel is all sorts of weird too. I'll press one button and it'll do something completely different than the button I pressed. I think something degraded in the membrane for the buttons. Not sure. Could be the weight of my PC on top of it too. Not great. Also last time I tried looking for it I couldn't narrow down where it was. I'm better at reading schematics now so maybe I'll find it in the service manual.

Sometimes cleaning the PCB under the membrane keyboard with a pencil eraser can help. Then wipe it off with isopropyl alcohol.

@@Neurochrome2010 Well I got to it today. Popped the plastic covers off the relays. Cleaned them up as good as I could. Couple tacks of hot glue to hold the caps back on. I thought the front panel would of had a membrane. Turns out they're just the typical square push buttons. However instead of having 4 legs on each corner. They only have two in the middle of either side. They all weren't going dead short when pressed, and some are paired up with a resistor so the MCU can tell what is pressed. Since the buttons weren't going dead short, I think it was confusing the MCU. I would've replaced them but didn't have that style so deoxit and worked it in. Come to think of it I might of been able to just rotate the 4 pin ones 45 degrees and made the replacement ones I have work. Oh well. Also the remote never worked for the thing. Messed with the IR sensor while I was there and got it working. Not sure if it was a dry solder joint or not. Re-flowed them just in case. Now the damn positive terminal on one of my speakers broke. Trying to glue the part back together but if that doesn't work. Just going to hard wire it with a knot on the inside. Just some old Yamaha speakers. They plug up to this Ensemble 4 sub that takes the output of the receiver and has terminals to go back out and to the speakers. Free yard sale stuff from a decade ago lol. Cheers.

That's disappointing. I'm not super surprised, though. Some things are too cheap.

@@Neurochrome2010 Do you have suggestions for the reputable brnds to minimize the chances for this to happen again? I don't need any more functionality than this thing gives, I only need it to work.

Yep: ua-cam.com/video/Vz0cEK4dX0A/v-deo.html The HP 6227B would be a good option too.

By the way, i opened my broken unit, and found that this time the reason is quite obvios - one of the components burned and shuttered in pieces. I could try to replace it if i knew what that thing was. So next time you open it in one of your videos, if you remember, could you check out U4 component and tell me its marking, please? Although yours look a bit different, i expect it is only the allignment.

I've gotten rid of both supplies I had as they had no use to me. Sorry, buddy.

The design documentation for the Input Buffer is made available when your order ships. Should you get stuck during the build I'm happy to help you. If you don't want the speakON but do want both RCA and XLR, I suggest getting the Neutrik RCA jack and mounting it in the speakON hole. You'll still have to drill a hole for the selector switch but that's manageable. It's easier for me to help you by email, so go to my website - www.neurochrome.com - and toss me an email through the Contact Us form.

I follow the AES48-2019 standard on this. If you want the EMI/RFI filter on the Modulus-86 to work you'll need to connect pin 1 to the Modulus-86 circuit board. This connection is also needed to ensure that the common-mode voltage remains within the allowed range.

You'll be hard pressed to build a lab grade power supply for $50-60. I often find used gear at lower cost than I can build something good for myself. The RK6006 is an interesting option. I highly doubt they would work well, but they could be interesting to look at, nonetheless.

@@Neurochrome2010 I'm still very much at the hobbyist level and hobby level tools. I only need something that I can current limit so I can inject voltage into shorted boards to pinpoint the component. Basic macbook/pc repair. I'm just not sure if I want to chance having a issue with the RK6006 module, or just pay $70 for the HM310 and be done with it. HM310 I get off Amazon, the RK6006 Aliexpress, and if I have a issue with it. Not as easily returnable. Its on Amazon too but with a $18 markup or so. Might as well buy the HM310. Thanks for the reply though. Still very undecided on what I want to get.

A cheap hack to get a current limiter is to insert a 10 Ω resistor in series with the supply output. That works great for testing power amps. If the amp misbehaves the resistor will cook and interrupt the flow of current.

@@Neurochrome2010 That goes beyond my knowledge. I'm not sure if that applies to a more digital circuit like a macbook logic board. I need to be certain that my current limiting is accurate. Else you could cook something like the SMC and the board is indefinitely a parts board once that happens. I was told 1V 2A is what I want to inject on my shorted rail, then feel around for hot components. Not to mention I'd like to do this more frequently, so having the right tool is ideal. Thank you nonetheless. I know this supply will work for what I need. It just seems like I'm paying more for less. If I where to build one with the RK6006, it'd be more easily repairable/maintainable down the road (providing the module isn't the issue) and I'd also gain fixed 3.3, 5 and 12v outputs. Going to check out your Part 2. Also local people know I'm looking for old equipment. Ideally get it damaged at a lower price, I currently cant justify $400 or so, even though its likely worth it.

In that case I would look for a lab supply that can provide 0-15 V at maybe 0-5 A. Ideally with a lower range of, say, 0-6 V. The HM310 will likely be just fine for your needs. Don't bother with the programming feature and save yourself some money.

Cool! Many of the cheaper DMMs won't go much past 440 Hz.

I can certainly take a look. 5A is a bit wimpy for an audio amp at 60 V, though. 10 A would be more interesting.

@@Neurochrome2010 5 amp or 10A would be your choice, I am going to use mine to power/test low amp LEDs, BTW,thanks for your quick reply .

You turn the amp on either with the push button on the front panel or with the 12 V trigger. Many higher end preamps have a 12 V trigger output that can be used for this.

No kidding!

Yeah. I'm not sure either. The 9115B certainly performs much better than the $100 supplies, but it does have its drawbacks. I wasn't aware of the HP/Agilent 6675A. It also needs 240 V input... I ended up settling on a pair of 6654A. I think they'll work well.

@@Neurochrome2010 Just yesterday I’ve seen a 6654A for 200€ in perfect condition (which is almost half the average asking price in Germany), but I can’t justify to buy another (heavy) power supply. I might regret not buying it. If I remember correctly they use a preregulator of some sort (to be expected at this power level), but still achieve very low noise. A teardown/test would be appreciated 😅 Yeah, haven’t thought about the 240V issue. Here in Europe that shouldn’t be a problem I guess.

EUR 200 is a great deal ... if the supply works. And actually not a bad deal if it doesn't. The front panel encoders often take a beating but they're easy to replace (I have a video on that too). I think HP just brute-forced it. Large heat sink, large fan, etc. I don't think there's a pre-regulator. At least I don't recall one from the schematic in the service manual.

@@Neurochrome2010 Yep, you're right and that is a bit crazy. Up to >500W of power dissipation, I guess. At least in my 6642A they do not use different transformer taps. And It must have been the 667xA series PSU I was thinking about - these do have preregulators.

$499 while supplies last. You can find it here: neurochrome.com/collections/connectors-parts/products/purifi-chassis The chassis comes with all the mounting hardware and mounting plates necessary to build the amp you see in the video.

@@Neurochrome2010 thanks for the reply

Yep. It's a power amp. You'll need some sort of volume control. I use the volume control that's built into my DAC.

@@Neurochrome2010 have u a video,for volume control,that's built one?????

Not yet.

I use a little current probe that I made: neurochrome.com/pages/measure-current-with-an-oscilloscope

I tried 10000 uF to no avail.

Not really. I've only tested that one. If you don't mind a fixed output voltage, any of Mean Well's offerings would be good options. I've used the RPS-400-27 in audio amps with excellent results. But for lab supplies I'd stick with the old HP/Agilent 6600-series.

Thanks, the MN LRS 150 24 is interesting because have a trimmer for fine Voltage settings. Maybe by replacing it with an higher impedance pot. the V.out can be regulated lower

That's likely. I'd be careful about such modifications, though. If you change the adjustment range on the power supply you also change the feedback loop. That can result in instability.

I will check impedance of original, then changing gradually with new one, for 12V there is LRS 150 12. Thanks for the tips

You're welcome. Also, if you don't mind the fan noise, the SE-600-series is excellent as well. I used to use a pair of SE-600-36 for testing power amps. I'm hoping that the pair of HP 6654A that I just bought will take their place (and allow for testing higher voltage amps too).

Oh, wow. That's no fun. You may be able to find a replacement through Mouser.com. Just search for 'encoder' and you'll find a bunch. You'll have to go through the data sheets for the mechanical dimensions to make sure they fit.

I just did my fix, added two caps(mlcc 100nF x2) to encoder pins, the original caps on board are 10nF which are next to the 10pin female connector. The encoder schematic is extremely simple, no external pullup resistors.

@@槑 wait, you can fix the encoder with capacitors? I thought the erratic behaviour was due to mechanical problems. I might as well give it a try.

Thank you. Yeah. I've become a lot more comfortable talking to the camera ... and better at video editing too. :)

I appreciate your input and suggestions, especially the one about grounding. I'll keep those in mind for next time. I did test to see whether a dynamic load would cause the supply to cycle between two ranges. That does not appear to be the case (good!).

@@Neurochrome2010 That‘s good to know!

The ferules are not in the signal path, though.

I specify ±1% tolerance metal film resistors on the BOM. There's no need for fancy "audiophile" resistors,. If you have a resistor kit already, I'd just use what you have. Just stay away from carbon composite resistors as they have very high excess noise. Carbon film is OK but metal film is preferred. Also note that I have a Modulus-86 Stereo Kit available. It comes with all the necessary parts so you don't have to hunt for them: neurochrome.com/products/modulus-86-stereo-kit

@@Neurochrome2010 thanks Tom. And for other components is it a similar story? As long as the components meet specification it should be ok? Just sometimes hear about people upgrading components of existing equipment and wondering if there's anywhere that's worth spending a bit more for higher quality, or standard stock stuff is fine in general for this type of design? Your kit is in my potentials list (though import duties to UK add some unexpected extra pain, and 2 unpopulated boards keeps it under the £135 duty threshold), may just need some practice first before jumping!

Honestly, in my not-so-humble opinion, the main feature of audiophile components is that they drain your wallet much, much faster than regular components. Audiophile components typically have worse specs on parameters that can be measured objectively. For example, I measured some audiophile capacitors a while back while I had access to an HP 4194A impedance analyzer. The audiophile capacitors had higher ESR and ESL than the plain vanilla Panasonic part from Digikey, i.e., the audiophile capacitors were further from the ideal capacitor than the off-the-shelf parts even though they were 40x the cost. There is no need - I repeat: no need; none; at all - for audiophile components in the Modulus-86 or any other circuit that I design. If you want to geek out with audiophile components you're free to do so. Just keep in mind that you will most likely get worse performance and you will pay much more. In the best case scenario there will be no difference between the performance with the audiophile parts and those I specify on the BOM, but there will be a significant cost added with the audiophile components.

I am planning a video on how to do distortion measurements on the cheap. So stay tuned.

It's pretty rare that I switch to batteries. The output impedance of a battery is pretty nonlinear, so they don't always offer good performance - especially with power amps. But they can be alright for line-level work. I used a pair of power tool batteries to power a precision oscillator at one point. That worked pretty well, but that was also a Class A circuit. Class A/B is a completely different ball of wax as I cover in a different video (ua-cam.com/video/j-zLrcLZLc0/v-deo.htmlsi=DbeDoq0GAsQb9q-1). Good point, though.

@@Neurochrome2010 I wouldn't use a battery for a power amp. Just low level stuff.

Heh... I find it more intuitive to go the other way around. Start with good test equipment so it doesn't get in the way of your design. Then characterize the circuits with a real-world supply (which can be a good one such as my Preamp Power Supply: neurochrome.com/products/preamp-power-supply).

@@Neurochrome2010 Well you must be making some pretty nice stuff I'll stay tuned. Anyways I thought we were talking about power supplies not so much test equipment.

I consider lab power supplies to be test equipment.

You're quite welcome. For higher output power, the HP/Agilent 65xx and 66xx series are hard to beat. I've been using a pair of 6643A for years for power amp testing and just picked up a pair of 6654A for higher power and higher voltage.

Sadly I'm not surprised. That's why I tested the ones on the Hanmatek.