Being critical however should not be judged as a threat but more as an attempt to keep eyes and ears open.
Absolutely - as long as we remain fact-based and avoid personal attacks and insults, a critical approach is definitely welcome.
I'm in West London; does anyone know (or anyone belong that is reading here) to one of these Clubs, near W4 post code?
I'm still weary of the Aluminium Case reflecting some RFI as a lot more current goes through these Amps than a DAC, right?
Thanks
I have a scope but I am wary it will show anything.
The only thing I could think of is that you are not filtering HF at the XLR jacks. A simple mod with a 100R resistor and 100p cap would close that avenue off.
Please read this link: https://onahighernote.com/blog/productfaq/linear-versus-switching-psu-in-mola-mola-kaluga/
It's really strange how lay people (especially those trained in the art of audiophilia by their peers who write for audio magazines) seem to think that switching power supplies are noisy. They're not. Given half a chance they're much quieter. All you need to take care about is of course the 100kHz and associated harmonics. Once I had that down the SMPS sounded much better than the big iron and copper affair that's incorrectly known as a "linear supply".
Quite a bold statement "it's a myth"
Ah English, it can be interesting when not read carefully.
Tom4s said
And I said
I doubt very much you will find a post in this thread where Bruno made the claims mentioned by Tom4s. It's a myth that keeps being retold, but the statements were never made. About the closest you will get is Bruno making a statement that it he finds it odd that some people are reluctant to use a switch-mode supply when they have adopted a switch-mode amp.
PS: BTW I raised with Theta the comments you linked to. Suffice to say they responded that while they very much enjoy their partnership with Bruno and agree on many things, they do not agree when it comes to the supply. Also, unfortunately, Stereophile weren't able to get a Kaluga to do a side-by-side shootout against the Prometheus, something they very much wanted to do and something I'd very much want to read about.
Tom4s said
And I said
I doubt very much you will find a post in this thread where Bruno made the claims mentioned by Tom4s. It's a myth that keeps being retold, but the statements were never made. About the closest you will get is Bruno making a statement that it he finds it odd that some people are reluctant to use a switch-mode supply when they have adopted a switch-mode amp.
PS: BTW I raised with Theta the comments you linked to. Suffice to say they responded that while they very much enjoy their partnership with Bruno and agree on many things, they do not agree when it comes to the supply. Also, unfortunately, Stereophile weren't able to get a Kaluga to do a side-by-side shootout against the Prometheus, something they very much wanted to do and something I'd very much want to read about.
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Besides, in that link an apparently very good SMPS (Mola-Mola Kaluga) was compared with an apparently not well measuring (and sounding?) linear supply:
".....Regarding the supplies, the proof is printed black on white in fig 4. in the Stereophile review of the Prometheus. Those 60Hz related components are simply nonexistent in the Kalugas. The most likely cause of those in the Thetas is the big toroidal transformer combined with the big capacitor tank and the rectifiers + associated wiring putting out a stray field. It's often said that toroids don't have a stray field. They do, and it's located where the wires come out. The field you get there is very nasty, consisting of 60Hz harmonics going all the way up into the kHz region. It's so strong that it is easily picked up by the speaker wiring so the amp output could be clean and you'd still get a buzz in the speaker as a result of the few inches of wire between the amp module and the chassis......."
Does that comparison make sense?
It is perfectly possible to construct a flawless linear supply in terms of hum, buzz and strayfields.
The economic factor (size, weight, cost) is very important so SMPS is much more attractive to the majority of manufacturers.
Taking the number of (active) components of SMPS and linear supplies into account (dissipation) a linear supply might be more reliable long term.
".....Regarding the supplies, the proof is printed black on white in fig 4. in the Stereophile review of the Prometheus. Those 60Hz related components are simply nonexistent in the Kalugas. The most likely cause of those in the Thetas is the big toroidal transformer combined with the big capacitor tank and the rectifiers + associated wiring putting out a stray field. It's often said that toroids don't have a stray field. They do, and it's located where the wires come out. The field you get there is very nasty, consisting of 60Hz harmonics going all the way up into the kHz region. It's so strong that it is easily picked up by the speaker wiring so the amp output could be clean and you'd still get a buzz in the speaker as a result of the few inches of wire between the amp module and the chassis......."
Does that comparison make sense?
It is perfectly possible to construct a flawless linear supply in terms of hum, buzz and strayfields.
The economic factor (size, weight, cost) is very important so SMPS is much more attractive to the majority of manufacturers.
Taking the number of (active) components of SMPS and linear supplies into account (dissipation) a linear supply might be more reliable long term.
Not sure about that. A linear supply requires rather large electrolytic capacitors - and they are not really known for their longevity...
Bruno (#1524):
".....The SMPS definitely sounds better. I haven't done the test with the Ncore modules but I did test the UcD400HG with the SMPS400 vs the HG supply. The SMPS is definitely better. It measures better too (THD at low frequencies). This is not illogical considering that the SMPS keeps the rail voltages symmetrical. This is discussed at length somewhere in this thread but one can be forgiven for having overlooked it among 1523 other posts...."
Indeed.
A 25 year old amp would only be from 1991. I have a lot of gear that is much older than that, and still works, but then again, I am really bad at throwing out stuff...
I would have expected that they designed the psu of the Theta flawless (given the pricetag) but I was surprised to learn this wasn't the case.
Thanks. I now remember that post. I also remember searching at length and in vain for where it was discussed at length. It wasn't. Why wouldn't a linear supply keep the rail voltages symmetrical?
Although I am not a classD fun, I compared a SMPS1200 with a linear PS in the same price range, on a class A/B amp
and found the to be SMPS1200 much much better.
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Sure we can have a look.
Unfortunately Modu are taking forever with the chassis work. In the meantime I am working on a new high performance regulated psu for 1A supply needs.
A "linear PS in the same price range" is very vague.
Could you provide specifications of that linear supply (type of power supply transformer, quality of capacitors and rectifiers, power rating, voltage sag at maximum power, and so on)?
And in what respect was it "much better"?
The linear was not something special: just a toroidal 500VA, 2 bridges 50A, 6 Philips 10.000uF and 6 bypass caps. like TNT-Audio PS.
I didn't do such measurements.
The SPMS was better in terms of transparency, dynamics, LF, HF and noise (hum).
http://www.diyaudio.com/forums/vend...-mosfet-amplifier-module-257.html#post4627019
I didn't do such measurements.
The SPMS was better in terms of transparency, dynamics, LF, HF and noise (hum).
http://www.diyaudio.com/forums/vend...-mosfet-amplifier-module-257.html#post4627019
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