Occam’s Razor then says there is no 20th order filter, just an ASRC to 44.1 kHz.The main thing is that the result will be the same - complete removal of higher harmonics and distortion after 24 kHz.
Occam’s Razor then says there is no 20th order filter, just an ASRC to 44.1 kHz.The main thing is that the result will be the same - complete removal of higher harmonics and distortion after 24 kHz.
A thinking person always has the right to change his mind!Occam’s Razor then says there is no 20th order filter, just an ASRC to 44.1 kHz.
I think that the full digital amplifier itself is still not well recognized in the audio world.Considering the features and the price, I'm surprised non a lot of people are buying the Sabaj A30a or other digital amplifiers such as the SMSL VMV A2 using the Axign AX 5689 IC. Also the Harman Kardon Citation Amp (using the same chip) apparently was a failure from the commercial point of view.
so then I tagged the right person@peterwen is looking for new product requests and product improvement ideas.
The first mass-produced fully digital amplifiers (FDA) appeared back in 2003.I got my first FDA around 2014 when I purchased a pair of Nubert nuPro A-300 active monitors that actually used 2x2 FDAs internally
I was mesmerized by the concept already at that time and I had high hopes that it will become more widespread and will evolve further
Then in the last 5-7 years I have never had any other FDAs but heard some models from FX-Audio and HifiMeDIY but those were not outstandingly good (they weren't bad either)
The Sabaj A30A (now on its way to me) will be my next FDA and I will be curious to compare it to my Topping DM7 and Hypex NC250MP combo
Comparing it with my Loxjie A30 I guess won't be that much exciting since I would expect the A30A to vastly supersede it
I would LOVE to have a multichannel FDA in the future though - I genuinely believe that it shall be the future of development: imagine just connecting one box to your computer via USB and there you have your multichannel system ready to go; no DAC, no hassle but great sound quality....
The 3rd problem is the most serious.Hola, new member, and new owner of an A30A, I've a couple of issues/questions with the amp and not sure whether to ask here or direct to @peterwen ?
1st, amp is linked via USB to my mac, I've been using soundflower to get native mac volume controls, this has worked on all my previous amps / outputs but trying to route to 'SABAJ USB AUDIO' gives me nothing, nada. Selecting the amp directly (bypassing soundflower and it's volume controls works fine)
2nd, I have a mixer & decks routed to the coax port, the only way I get any volume is maxing the mixer's coax output to +18db and turning the amp volume past 80, 100 on the coax input volume is equivalent to about 40 on the other inputs. (optical goes to a pi with Kodi, analogue goes to a record deck so I can't use another input port)
3rd, most crucial issue, swapping between inputs gives me a very loud thump, (loud enough for me to worry about the health of my sub/speakers), thump is *not* effected by volume control, eg, volume at 1 still gives a loud thump from speakers & sub
I've not updated the firmware having seen the previous posts about volume being effected (which would be a huge issue for the mixer volume above)
Does anyone know how I might get any of these resolved?
So the 3rd issue is sorted. I pulled everything apart, amp was still popping with all inputs disconnected, disconnected the sub and the pop vanished!The 3rd problem is the most serious.
Does the pop noise occur even if all cables (USB, OPT, COAX, AUX, SW-out) other than the A30a's power supply and speaker cables are disconnected and the input is switched?
If the resulting pop noise still occurs, reset the A30a by pressing the main dial by selecting RESET in the menu item.
If the pop noise comes out even after resetting, I judge that your A30a is malfunctioning.
Ask your retailer to exchange or return the A30a.
Thank you for your report.So the 3rd issue is sorted. I pulled everything apart, amp was still popping with all inputs disconnected, disconnected the sub and the pop vanished!
I'm using an REL T5i sub woofer, REL's documentation recommend using high level pickups taken straight from the speaker terminals, worked fine on my Peachtree amp, worked fine on my Arcam, makes the Sabaj amp grumpy. I've moved to line RCA for the sub and all is now well. I'm presuming this is related to class D vs Class A/B & G of the previous amps. The REL specs say it will work with class D but obviously something amiss.
Just the coax volume and USB interface which I'm guessing will be a firmware update? (if I get very lucky!)
Referenced to what?A half voltage of the power supply voltage is applied to the speaker terminals.
This is the basic knowledge for using BTL amplifiers.Referenced to what?
I was using high level as the REL documentation said it was supported on class D, have reverted to a line input to solve the thumping noise.Thank you for your report.
Were you connecting the A30a's speaker output to the REL T5i's Hi Level input?
The A30a amplifier method does not allow Hi Level connections like class A/B amplifiers. Abnormal current flows and the protection circuit is activated frequently. In the worst case, the amplifier section of the A30a will be damaged.
If you use a subwoofer with the A30a, be sure to use the RCA SW-OUT to connect to the Low Level input of the REL T5i.
Do not connect anything other than speaker cables to the speaker terminals of the A30a. Also, do not connect the negative terminals of the speaker terminals to a common connection.
A half voltage of the power supply voltage is applied to the speaker terminals.
The following are the improvements that can be made by updating the firmware.
1、Added "SPDIF SENSE" option in the menu. Users can choose the appropriate value according to their own needs. When there is no sound from the optical input, increase this value to match the optical output device with larger clock jitter (eg TV /game console).
2, The SW output is properly mixed with R-ch and L-ch issue.
3, Optimized the volume curve.
4, Added "SUB OFF" option.
Thank you for the long explanation but you still have not answered my question. A voltage is a difference between two points.This is the basic knowledge for using BTL amplifiers.
A PWM type STA516BE is used for the output amplifier of A30a with BTL connection.
In addition, the output of most class D amplifier products and full digital amplifiers such as SMSL VMV A2, SA400, AIYIMSA D03 is also BTL type like A30a.
The BTL method is a method that obtains a large output by pairing two amplifiers and is used in many amplifier products.
However, the speaker terminal is applied with half the voltage of the power supply voltage, which limits its use.
For details, if you search for "BTL method" on the web, you will find many commentary articles.
``Restrictions on the use of BTL amplifiers''
You cannot connect anything other than speakers to the output.
The signal for SW cannot be extracted from the speaker terminal.
Only products that switch between + and - can be used as a speaker switcher.
Etc···
Unfortunately, there are few examples that describe these things in the manual.
The actual A30a STA516BE circuit uses PBTL with parallel BTL connections for R/L-ch. (Attachment STA516BE-3)
"BTL/PBTL type amplifier"
Topping: All amplifiers except LA90
SMSL: All amplifiers except VMV A1, A300 (2ch mode)
Sabaj: All amplifiers except A5/A8, A10a 2022/A20a 2022 (2ch mode)
Loxjie: All amps
AIYIMA: Most class D amplifiers such as A07/A04/A200/A08Pro/A08/D03/D05
I asked:A half voltage of the power supply voltage is applied to the speaker terminals.
Referenced to what?
Well, these amps usually have a single voltage supply. So to work properly, they swing one side of the amp inverted from the other side, you you can still have full swing output. Consequently, the resting voltage (no signal) will be half of the supply voltage. The reference here is the GND.I am still asking: that half voltage that is applied to the speaker terminals are referenced to what? Obviously that voltage is not between the two speaker terminals. How does one measure that voltage?
Is the half PSU voltage measured between GND (as the ground of the RCA sockets) and either of the positive (red) and minus (black) speaker terminals?Well, these amps usually have a single voltage supply. So to work properly, they swing one side of the amp inverted from the other side, you you can still have full swing output. Consequently, the resting voltage (no signal) will be half of the supply voltage. The reference here is the GND.
Yes, at rest, both should show the same (half VCC) voltage. If there is a signal, they will move in opposite directions.Is the half PSU voltage measured between GND (as the ground of the RCA sockets) and either of the positive (red) and minus (black) speaker terminals?
No idea, that may differ per specific implementation.Do you know if GND is connected to the power connector earth connection?
How? All units are manufactured the same, isn't it? Either the case is earthed or it is floating. There is no signal I can see on the device photographs to say either, hence my asking as you seem to know the unit.No idea, that may differ per specific implementation.