Starkrimson (BOSC) by Orchardaudio VS Purifi 1ET400A (and EVAL1 or neurochrome board?)

[yoodog]

hi guys trying to grasp what is a better amp - both are great no questions, but I tried to compare they specs and graphs.
- according to graphs posted in Orchardaudio page (starkrimson), most of them are not as good as Purifi (1et400a) measurements
- But Orchard Audio website specs for some rerason show better values than on their own graphs in the link above (it is possible that graphs were measured on an older HW version, but there is no way to know, may be they just show better numbers on the webpage )
- Orchard Audio seems a lot easier to incorporate into DIY projects I think (looks alot less scary no matter how amateur it sounds - have you seen Purifi manual I mean )

 

[restorer-john]

@SIY has extensively tested both these amplifiers in a review for AudioXpress magazine.

I can't seem to find the link @orchardaudio posted to the PDF.

 

[yoodog]

https://audioxpress.com/article/fre...d-audio-bosc-and-purifi-audio-eigentakt-eval1

you mean this? found it yesterday. it is quite interesting indeed. And I actually agree 100% from comparing available charts. Purifi cost about same over all without EU tax as Orchardaudiio Starkrimson amp, but Purifi graphs are better over all in my opinion, even though the other is def amazing and clean amp, just not as much. QC seems to be even better than Purify based on consistency between ch and so on, but again, both "know what they are doing" Later one is def easier to implement / or more like - less confusing due to luck of details and IO pin head and shit

 

[orchardaudio]

hi guys trying to grasp what is a better amp - both are great no questions, but I tried to compare they specs and graphs.
- according to graphs posted in Orchardaudio page (starkrimson), most of them are not as good as Purifi (1et400a) measurements
- But Orchard Audio website specs for some rerason show better values than on their own graphs in the link above (it is possible that graphs were measured on an older HW version, but there is no way to know, may be they just show better numbers on the webpage )
- Orchard Audio seems a lot easier to incorporate into DIY projects I think (looks alot less scary no matter how amateur it sounds - have you seen Purifi manual I mean )

What spec are you specifically looking at. Let me know if you have any questions.
www.orchardaudio.com/contact-us

 

[orchardaudio]

Starkrismson is now the new name of BOSC. Also, I am very happy to report that I have changed the input impedance of the amplifiers to 44k, without any degradation to performance.

THD Ratio vs Power into 8-ohm load


Multitone:


Wideband FFT of with -60dB input:


THD+N Ratio vs Frequency @ 10W:

 

[orchardaudio]

Save 15% during our holiday sale through December 10th.

www.orchardaudio.com/shop

Use code "holiday15%" at checkout.

 

[Head_Unit]

Multitone

From another thread entirely, maybe not even on this board, someone compared a multitude into a resistor and then into an actual speaker. Could you do that? It would be very interesting. Maybe in one of the other threads you started, or maybe a new thread. The hypothesis was that the reactive load caused a large degradation in performance with some little Class D amp compared to a test resistor, and that it was an interesting phenomenon, and could be a kind of merit of an amp to have less difference. Of course comparisons would be meaningless without some standardized speaker load simulation, which will not represent all speakers, and due to lack of motion not really be like a speaker.
BUT it would still be interesting

 

[orchardaudio]

From another thread entirely, maybe not even on this board, someone compared a multitude into a resistor and then into an actual speaker. Could you do that? It would be very interesting. Maybe in one of the other threads you started, or maybe a new thread. The hypothesis was that the reactive load caused a large degradation in performance with some little Class D amp compared to a test resistor, and that it was an interesting phenomenon, and could be a kind of merit of an amp to have less difference. Of course comparisons would be meaningless without some standardized speaker load simulation, which will not represent all speakers, and due to lack of motion not really be like a speaker.
BUT it would still be interesting

This was done by a third party (@SIY), you can see here:
https://audioxpress.com/article/fre...d-audio-bosc-and-purifi-audio-eigentakt-eval1

Summary: They found no difference between resistive load vs dummy speaker load.

For me, it is not practical to drive a speaker at that power level, as it will make me deaf real fast. I do not have an anechoic chamber.

 

[Head_Unit]

For me, it is not practical to drive a speaker at that power level, as it will make me deaf real fast. I do not have an anechoic chamber.

Oh that is simple, move the speaker outside and point it at the neighbors! More seriously the measurements are really amazing, congratulations. I still have to look for the thread I referenced, they used multi-tone with a resistor and then a speaker. A lot more junk with the actual speaker so maybe that would be a good test.

On a different note, how about driving lower and lower impedances compared to Class AB? I worked for a giant autosound company whose managing director for amplifiers was explaining to me that the losses increased tremendously as you went from 4 to 2 to 1 ohm (square of the current though not really that simple, especially as there was also DC-DC conversion involved). In setups like your topology does that still hold true? Or not at all? Or what happens? (My hypothesis was that in those DC-DC Class AB scenarios I do not believe you get more actual dynamic power at clipping into the lower impedances, though I could never get time to implement a measurement setup to definitively prove or disprove it.)

 

[orchardaudio]

Oh that is simple, move the speaker outside and point it at the neighbors! More seriously the measurements are really amazing, congratulations. I still have to look for the thread I referenced, they used multi-tone with a resistor and then a speaker. A lot more junk with the actual speaker so maybe that would be a good test.

On a different note, how about driving lower and lower impedances compared to Class AB? I worked for a giant autosound company whose managing director for amplifiers was explaining to me that the losses increased tremendously as you went from 4 to 2 to 1 ohm (square of the current though not really that simple, especially as there was also DC-DC conversion involved). In setups like your topology does that still hold true? Or not at all? Or what happens? (My hypothesis was that in those DC-DC Class AB scenarios I do not believe you get more actual dynamic power at clipping into the lower impedances, though I could never get time to implement a measurement setup to definitively prove or disprove it.)

Regardless of amplifier technology, you cannot change physics.
100W into 8-ohm is 3.535A
100W into 4-ohm is 5A (1.414 x 3.535)
100W into 2-ohm is 7.071A (1.414 x 5A)
100W into 1-ohm is 10A (1.414 x 7.071A)

While the output power stays the same the current increases by a factor of sqrt(2) or 1.414 every time you half the load. So amplifier has to be able to supply the higher current.

 

[Head_Unit]

While the output power stays the same the current increases by a factor of sqrt(2) or 1.414 every time you half the load.

I think I did not word my question well, sorry. What I understood form the managing director was that for DC-DC Class AB the losses would also be the square of the current (maybe not exactly, there was a lot of sake involved in this discussion ). That gets HUGE at lower impedances. Since Class D operation/topology is different, my question is when you go from 8 to 4 to 2 to 1 ohm, how much do the losses increase? (And thus the efficiency decrease?).

 

[orchardaudio]

The conduction losses in class-d also increase with the current. There are multiple elements in class-d that pass the current, mainly the switching devices and the inductor in the output filter. These elements have resistive components. The power loss in the resistive components is R*I^2. The R stays constant for the most part so the loss increases exponentially with an increase in current.

So the efficiency of a class-d amp will also be worse with 100W into 4 ohm than with 100W into 8 ohm for example.

For example in my 150W Starkrimson monoblocks, the inductor has a DCR of 9.6mohm:
So for 100w into 8 ohm the inductor will dissipate 120mW (3.535 x 3.535 x 0.0096)
So for 100w into 4 ohm the inductor will dissipate 240mW (5 x 5 x 0.0096)

 

[Spinitch]

OA - specs suggest with US plug option should work in Japan, East or West? Can swap plug and use in most other countries. US of course.
Ext. Power Supply Input Voltage: 90 to 264VAC
Ext. Power Supply Input Frequency: 47 to 63Hz

 

[orchardaudio]

OA - specs suggest with US plug option should work in Japan, East or West? Can swap plug and use in most other countries. US of course.
Ext. Power Supply Input Voltage: 90 to 264VAC
Ext. Power Supply Input Frequency: 47 to 63Hz

The amplifiers will work anywhere in the world, and if you look at my website I offer 5 different plug options which cover most of the world. Yes the US power cord also works in Japan.

 

[Trouble Maker]

The amplifiers will work anywhere in the world, and if you look at my website I offer 5 different plug options which cover most of the world. Yes the US power cord also works in Japan.

View attachment 119868

Be careful if the device is grounded, (almost?) none of the outlet's in Japan have the third/ground prong.
You can get an adapter that goes from 3 prong to 2 prong, with a wire for the ground.

They sell these everywhere, you might even be able to get them at a conbini, convince store, which are everywhere and open 24/7/365. But I'm 100% sure you can get them at most hardware (Kamashin, Kanseki), electronics (Yamad Denki, Yodobashi Camera) and home goods stores (Nitori, Tokyo Interior); between these kinds of stores most people will have one of these close by.

However, at least in our apartment not many of the outlet's had the ground connector; I think only the microwave, toilet (bidet/heated seat) and maybe the refrigerator. I'm guessing this is pretty normal there.

Or some devices sold there will have the ground wire built in, but split off from the main plug. I think our moven (microwave oven) and bidet was like this.

I had to get those adapters for my LS50Ws that we took over, but just cut the ground wire off since the outlets they were by didn't have that ground connection. I guess I like to live dangerously.

 

[Andykay]

https://audioxpress.com/article/fre...d-audio-bosc-and-purifi-audio-eigentakt-eval1

you mean this? found it yesterday. it is quite interesting indeed. And I actually agree 100% from comparing available charts. Purifi cost about same over all without EU tax as Orchardaudiio Starkrimson amp, but Purifi graphs are better over all in my opinion, even though the other is def amazing and clean amp, just not as much. QC seems to be even better than Purify based on consistency between ch and so on, but again, both "know what they are doing" Later one is def easier to implement / or more like - less confusing due to luck of details and IO pin head and shit

Yeah read that article it doesn't say too much really. Not useful .

 

[restorer-john]

Yeah read that article it doesn't say too much really. Not useful .

Yeah OK.

Pretty much the most comprehensive article and review to date.