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[natehansen66]

Cool thanks!! I do have a question as it looks like you have xlr jacks for input. I've read Bruno's pin 1 paper several times now, as well as studying their drawings. I've also gone through the Rane tech note about balanced signal grounding. From all of that (if I understand correctly, big if!) I'm I under the impression that the cable shield should be grounded to the chassis at the input, and signal ground from the board at a separate location, yet every implementation I've looked at online has positive, negative, and shield connected from the amp board to the input jack. Am I misinterpreting the info or does everybody else have it wrong (I doubt it!)?

[mwillems]

Cool thanks!! I do have a question as it looks like you have xlr jacks for input. I've read Bruno's pin 1 paper several times now, as well as studying their drawings. I've also gone through the Rane tech note about balanced signal grounding. From all of that (if I understand correctly, big if!) I'm I under the impression that the cable shield should be grounded to the chassis at the input, and signal ground from the board at a separate location, yet every implementation I've looked at online has positive, negative, and shield connected from the amp board to the input jack. Am I misinterpreting the info or does everybody else have it wrong (I doubt it!)?

I am using XLRs and my pin 1 is directly connected to both the chassis and to the input cable shield. On the amp side the cable shield is connected to the input "ground" tab on the amp board.  I did that based on this Hypex wiring diagram: http://www.hypex.nl/docs/appnotes/wiring.pdf .  It shows a direct connection between the amp input ground tab and pin 1 through the cable shield (on the right side).  

The idea (as I understand it) is that all the grounds should be the same ground (chassis ground and audio ground are the same).  He discusses it to some extent in the grounding paper as well, about half way down the first page: http://www.hypex.nl/docs/appnotes/earth_appnote.pdf

If you're referring to his comment in the pin 1 paper about needing to tie the audio circuit to the chassis "elsewhere," I agree that's a confusing comment that appears to contradict his wiring diagram.   I think the answer lies at the top of the first page of that same paper: http://www.hypex.nl/docs/appnotes/pin1_appnote.pdf  

He quotes a common customer question: "Your amp module connects the audio ground to the chassis. This will cause hum when connecting. Can you please insulate the heatsink."  I read that as saying that the amp grounds the audio circuit to the chassis through the heatsink, as well as through the amp ground tab.  Basically, I think the amp's design furnishes the additional chassis ground connection "elsewhere," when the heatsink is mounted to a metal chassis.  

I admit that that's a somewhat "close reading" of the pin 1 paper, but I can think of no other way to reconcile that comment with the wiring diagram, which is pretty clear on what should happen.  I can say that I've had no ill effects and no ground hum from following the wiring diagram attached above.

[natehansen66]

Ok thanks for taking the time to help, I should be good to go. UPS guy dropped a box full of UcD modules with a PS today, and the chassis should be in tomorrow.........I'm gonna be drilling holes this weekend 

[mwillems]

Ok thanks for taking the time to help, I should be good to go. UPS guy dropped a box full of UcD modules with a PS today, and the chassis should be in tomorrow.........I'm gonna be drilling holes this weekend 

Sweet, let me know if I can help with anything else.  I'm excited to hear your impressions.

[kiwi]

Just to chime in... I am absolutely loving my hypex amps... I'm not in the "low wattage" category, with my Magnepans... but the amps are absolutely wonderful.  One of the simplest DIY setups going.  Just connect and plop into cases.

[Appelbom]

This was a great read!

I´m in a similar situation with a BMS4554 sitting in an 18sound horn. Looking for that ultimate low watt, low noise amp.
Any development or new alternatives since this thread was established a few years back??

Cheers

[mwillems]

This was a great read!

I´m in a similar situation with a BMS4554 sitting in an 18sound horn. Looking for that ultimate low watt, low noise amp.
Any development or new alternatives since this thread was established a few years back??

Cheers

I'm still happily chugging along with my hypex ucd 180's suitably modified.  A good friend of mine is using a First Watt J2 for a similar set of horns, and he's very happy with the sound. It's a nice piece of kit, but a class A amp can get a bit toasty :-)

[Appelbom]

Thanks for the update and the nice thread!

[Mitchco]

An alternative is the Amp Camp Amp kit: https://diyaudiostore.com/collections/frontpage/products/amp-camp-amp-kit?variant=21206375620  They are currently out of stock, but often replenished.

Simple to build and excellent sound quality. Even with the SMPS, they are low noise amps and with a voltage gain of 14 dB, one does not need to pad down the compression driver. Mine are running JBL 2453h -SL compression drivers and could not be happier.

[mwillems]

An alternative is the Amp Camp Amp kit: https://diyaudiostore.com/collections/frontpage/products/amp-camp-amp-kit?variant=21206375620  They are currently out of stock, but often replenished.

Simple to build and excellent sound quality. Even with the SMPS, they are low noise amps and with a voltage gain of 14 dB, one does not need to pad down the compression driver. Mine are running JBL 2453h -SL compression drivers and could not be happier.

That's a heck of a deal for a Pass-designed amp, even if it is build it yourself.  I certainly know what my next amp project will be if the UCD's ever burn out.

[natehansen66]

I'm also still using my modified Hypex ucd180..... About 4 years now. Not low wattage but low gain. Very little hiss from my horns. I don't see any reason to try anything different.

[astromo]

An alternative is the Amp Camp Amp kit: https://diyaudiostore.com/collections/frontpage/products/amp-camp-amp-kit?variant=21206375620  They are currently out of stock, but often replenished.

Simple to build and excellent sound quality. Even with the SMPS, they are low noise amps and with a voltage gain of 14 dB, one does not need to pad down the compression driver. Mine are running JBL 2453h -SL compression drivers and could not be happier.

Thanks to this post, kudos to you Mitchco, I built myself two ACAs. They're running as fully balanced monoblocks (one side benefit - the balanced design helped deal with a hum hassle I had, so that was worth the effort right there).

My speakers aren't as sensitive as mwillems (91 dB @ 1W/1m) but even so, these little guys do a darn fine job. The latest form of the ACA is the v1.6 (i.e. v1.5 with 24VDC PSU). See here for relevant performance graphs:
https://diyaudiostore.com/products/meanwell-24v-5a-psu-with-power-cord

Just took a while for the kit to become available and then get delivered ... and then get built. My first go wielding a soldering iron and I had power on with no smoke for both units and so far so good. That's a special feel (made me smile the first couple of times) listening to music I "made" myself.

I'm still happily chugging along with my hypex ucd 180's suitably modified.  A good friend of mine is using a First Watt J2 for a similar set of horns, and he's very happy with the sound. It's a nice piece of kit, but a class A amp can get a bit toasty :-)

My ACAs' fins warm up to about +25°C above ambient, so 45-50°C. That's not too hot. I just keep them in a well ventilated spot - can't keep them locked up. A single ACA is pretty cheap / easy, if you want to try something different, then keep it in mind.


mwillems, what are the details of the speakers you've got? Were they a buy or DIY?

[mwillems]

I'm still happily chugging along with my hypex ucd 180's suitably modified.

So to follow up, a few months ago, following a power outage, my Hypex amp would not turn on.  I tried replacing the fuse and a few other tricks, but no dice.  It turned out the SMPS power supply had failed after being on more or less continuously inside my entertainment center, with limited ventilation, for five years    The amp modules were fine despite all that, but I was quite embarassed I never thought to measure the temperature.

So I replaced SMPS and all is running well again. I've found some suggestions for how to fix a failed SMPS, but I figured that would be a fun rainy day project to make a spare, and I needed audio in the meanwhile.  Worth noting for anyone considering a Hypex build: if you run your hypex amp continuously with the metal amp box inside a wooden entertainment center with passive cooling (read ventilation holes and no fans), it may only last five years!  I've since taken the doors off the entertainment center and things run much cooler now.

mwillems, what are the details of the speakers you've got? Were they a buy or DIY?

I built mine; we call them the "War Horns".  They're about 13 cubic feet (2'x3.5'x2') and they took almost two years to build (at a relaxed pace).  The low ends each use a 2x2 array of peerless 8" woofers up to about 800Hz.  The high ends (above 800Hz) are slightly modified Altec 511B horns (from the "voice of the theater") but using a newer compression driver (now using a pair of used JBL 2426s with aftermarket diaphragms, but I originally used a pair of BMS drivers).  The -3dB point on the low end is around 27Hz, and they play up to 20KHz or so (but they start beaming a bit by 14KHz).  The power handling of the speakers and amps should (in theory) run up past 120dB, but I don't think I've ever run them that loud.  I also run a frankensub that only has the .1 channel from movies routed to it. 

JRiver is (mostly) my crossover and pre-amp feeding into a Steinberg UR824 which feeds the Hypex amps (the modified UcD180's on the high end, and a pair of UcD400's on the low end). I did have to break down and get a MiniDSP 2x4 that I use as the system default output though (feeding the Hypex amps as well). I was having lipsync issues with the WDM driver on windows that I simply could not cure reliably, and I've been trying to transition all my PCs to linux anyway, but there are no input options in JRiver on Linux.  So the MiniDSP seemed like an option.  It doesn't have the same power and flexibility as JRiver, and doesn't have the same low distortion as the Steinberg, so it will never be a real replacement for critical listening, but it's good enough for streaming video from the web or playing video games, and despite the not great electrical specs it works fine with a 10dB pad inline.

I'm hoping the War Horns are the last set of speakers I ever need; I've been using them for more than five years or so now and I never get tired of hearing them.

[Mitchco]

Thanks to this post, kudos to you Mitchco, I built myself two ACAs. They're running as fully balanced monoblocks (one side benefit - the balanced design helped deal with a hum hassle I had, so that was worth the effort right there).

My speakers aren't as sensitive as mwillems (91 dB @ 1W/1m) but even so, these little guys do a darn fine job. The latest form of the ACA is the v1.6 (i.e. v1.5 with 24VDC PSU). See here for relevant performance graphs:
https://diyaudiostore.com/products/meanwell-24v-5a-psu-with-power-cord

My ACAs' fins warm up to about +25°C above ambient, so 45-50°C. That's not too hot. I just keep them in a well ventilated spot - can't keep them locked up. A single ACA is pretty cheap / easy, if you want to try something different, then keep it in mind.

astromo - cool! I recently upgraded my ACA's to the Meanwell 24v supplies and rebiased. The compression drivers I use have a sensitivity of 113 dB SPL, 2.83V (1W) @ 1m (3.3 ft). No padding, just a protection cap. Dead silent, with the faintest hiss only when the ear is right up to the compression driver.

Re: 50°C well that sounds about right - Crikey Hot!

How do you like the sound quality :-)

[astromo]

mwillems / Mitchco

Do you have a DIY speaker design you can share?

High sensitivity speakers could add up to a whole lot of purity or extreme depending on how you cut your cake.


I'm really enjoying putting the ACAs through their paces. They show excellent detail. Some of my standard audio test tracks are Alan Parsons "Sirius"/"Eye in the Sky" and Jeff Wayne's "Eve of the War" and when they're delivered they result in the right emotional response for me. I've cranked it with a Schiit Freya as the pre .. works for me .. clear without distortion and at party going levels in my main living room with its lively wooden floor. Yes, Mitchco the quality is there as far as I'm concerned, even if I don't have sound engineer's ears. Thanks for the tip off, really appreciated.

All that said, I did notice a lack of drive way down low with Beasties Boys "Brass Monkey" but that sort of bass is a real test and not normal for my standard listening repertoire (I don't consider this a negative at all btw - this wasn't part of the functional spec). So, I'm planning on an Aleph J build (for more power / bass definition) for the living room and the ACAs will head to my studio. In the studio I've got speakers set up close in, so very little gain is required.

[mwillems]

mwillems / Mitchco

Do you have a DIY speaker design you can share?

Not as a CAD file or in a neat package; I worked out some general ideas in software simulators, and then I sketched out my designs long hand.  A lot of the hard work was done with a microphone and DSP after I finished the build.  If you can share some design parameters (i.e. what you're looking for exactly), I can definitely share relevant tools I used in designing mine, and some lessons learned over building a few dozen speakers over the years.  But really, if you plan to use JRiver or a DSP box in front of the speakers as the crossover, that frees up a lot of design space; traditional speaker design emphasizes selecting drivers and cabinet dimensions to maximize the flatness of frequency response and to minimize the power loss in the crossover (doing serious DSP in analog is hard and expensive). When you have near infinite DSP at your disposal, you can pick your elements and box to prioritize low distortion, high sensitivity, or solid deep bass extension, knowing that, if there are a few ripples or a big difference in sensitivity, you can worry about it "post-production."  Obviously there are limits (some driver faults can't be fixed, and a ported box will always sound somewhat different than a sealed box), but it opens up the options quite a bit.  For example, my high-end is about 20dB more sensitive than my mid-bass, which would involve throwing away a lot of power with a passive crossover, but is trivial to resolve when bi-amping.

A good place to start with rough cabinet dimensions is something like WinISD (http://www.linearteam.org/) or "The Edge" (http://www.tolvan.com/edge/help.htm).  In WinISD you can plug in the parameters for drivers you're considering and vary the box volume and design to see how your bass will look.  The Edge will then help you figure out the best place to put the drivers in the box.  I could offer a lot more on various subjects (especially construction techniques), but I'm rambling.

[Mitchco]

mwillems / Mitchco

Do you have a DIY speaker design you can share?

High sensitivity speakers could add up to a whole lot of purity or extreme depending on how you cut your cake.
...

Try a variant of Zilch's famous Econowave designs: https://www.diysoundgroup.com/htm-12-kit.html

Zilch's thread: http://audiokarma.org/forums/index.php?threads/zilchs-ak-design-collaborative-econowave-speaker.150939/

Cheers!

[mwillems]

Try a variant of Zilch's famous Econowave designs: https://www.diysoundgroup.com/htm-12-kit.html

Zilch's thread: http://audiokarma.org/forums/index.php?threads/zilchs-ak-design-collaborative-econowave-speaker.150939/

Cheers!

I hadn't thought about Zilch in a few years; his compression driver measurements were instrumental when I was picking drivers way back when. 

[astromo]

Thanks for that feedback the pair of you.

Speaker building is not a first priority for me right now. It's more a case of fact finding.

It also sounds like I'm better off learning up about cross-overs in depth, as a first port of call.

Cheers

[mattkhan]

Best way to do that (imv) is to build a speaker 

[astromo]

Best way to do that (imv) is to build a speaker 

I dare say you're right and applying that logic means that I'd need to work out the most appropriate for my capabilities and understanding .. it's a journey, for sure.

[mwillems]

I personally found Rod Elliot's articles on bi-amping and cross-overs to be very helpful in orienting my thinking: http://sound.whsites.net/articles.htm

He talks about the advantages of active speakers with separate amplification for each stage, and some general principles of crossover design at a high level.  His other articles are quite good too.