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Hi!

Welcome to my DIY audio forum.

Cheers
Per-Anders Sjöström

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#1
Phono RIAA amplifiers / Re: QSXM2 - My realisation
Last post by slimak - June 26, 2022, 04:29:44 PM
#2
Phono RIAA amplifiers / QSXM2 - My realisation
Last post by slimak - June 19, 2022, 08:30:05 PM
QSXM2 from Slovakia :-)
Very nice sound.
#3
Power supplies / Re: SSR01 => unregulated DC in...
Last post by peranders - May 18, 2022, 06:35:36 AM
I'm sorry I forgot to answer you. The regulator has up 120 dB PSRR so it means 1 v ripple ends up with 1 uv ripple out. The only thing you must pay atttention to is min and max voltage in. If you use the preregulator then min voltage is 4 volt more in than your output voltage. Without preregulator it's 2.5 volt.
#4
Power supplies / Re: SSR01 => unregulated DC in...
Last post by kunlun121 - May 11, 2022, 02:18:26 PM
In the end I was happiest with a 100uF smoothing capacitor. That is not a typo. (Measured load was 40mA rather than simulated 18mA.) It leaves a significant ripple for the SSR01 to deal with, but with 10V headroom in unregulated DC input this was no problem to eliminate for the super regulator: there was no measurable AC on the SSR01 output. The turntable sounded better with each reduction of smoothing capacity. Lower than 100uF probably won't be useful but I may yet try 56uF so see what happens. The super regulator is a weird and wonderful device.
#5
Power supplies / Re: SSR01 => unregulated DC in...
Last post by kunlun121 - April 18, 2022, 01:30:27 PM
Your SSR04 uses 2200uF. I started out with around double that, but it didn't sound right. Too slow and heavy. At around 2000uF it's already much better. I'd like to try and reduce it further, but ripple will keep increasing. I have an LTSpice model of my rectifier bridge and smoothing caps that sit before the SSR01. By varying the load it is quite easy to see the resulting amount of ripple. Can you give some guidance of the maximum amount of ripple that you'd recommend is okay for the SSR01 to receive?
#6
Power supplies / Re: SSR01 => unregulated DC in...
Last post by kunlun121 - April 16, 2022, 10:41:26 PM
I'll take a look. The current consumption looks like it's around 15-20mA.

Rephrasing the question, how much ripple can I feed the SSR01 (30V version) before the SSR01 begins having trouble rejecting it?
#7
Power supplies / Re: SSR01 => unregulated DC in...
Last post by peranders - April 06, 2022, 07:44:50 PM
For inspiration you can check how SSR04 is designed.

Important for design: What is the max current consumption of your amps?
#8
Power supplies / SSR01 => unregulated DC input ...
Last post by kunlun121 - April 03, 2022, 07:30:17 PM
Hi Per-Anders,

I'm trying to figure out how to best provide unregulated DC power to the SSR01 boards. I am using a toroidal transformer and a basic discrete full wave bridge rectifier with some smoothing caps before the SSR01.

I'd like to know how much smoothing is necessary. Or better, the minimum amount of smoothing I can get away with. Can you advise about the minimum total size of the smoothing capacitance required for optimal operation of the super regulators? Or would you advise to maximise smoothing capacitance given the available space on my boards?

The application at hand is the 30V version I ordered the boards for. I want to use it for a minimalistic phono stage, so the load is pretty insignificant. But I'd like to know this number for different voltages / applications too. Is there relatively straightforward way of calculating that for different voltages? What are the relevant variables in determining the minimum smoothing capacity?

Thank you for looking into this.

BTW and off-topic: please find some other way of ascertaining that I am not a robot. These letter combination images are impossible to read, also for a living breathing if ageing human in need of reading glasses...
#9
Phono RIAA amplifiers / Re: QSXM2 troubleshooting!!
Last post by W1DAN - February 13, 2021, 01:57:44 AM
Hej Per Anders!

I would like to increase the gain about 6dB. Would I increase R51 to do this?

I am using a MM cartridge and the preamp is working pretty well (still have an issue with the right channel DC offset without input termination).

Thank you,
Dan
#10
Phono RIAA amplifiers / Re: QSXM2 troubleshooting!!
Last post by W1DAN - February 01, 2021, 02:57:29 AM
Per Anders:

The RIAA stage came up fine for the left channel. On the right channel RIAA section I still have some offset on the output when the preamp has 10mv at TP1. For now I inserted a 10UF capacitor in series with R93, and the main output DC is now fine.

On the preamp DC servo amp IC1, when my test oscillator is set to 20hz, I see a sine wave on the output pin 6, as well as a little at C9. Would this AC audio correction signal "subtract" the from the main signal low frequency audio? Either way I added 10uF across C9 to make the correction voltage pure DC.

I'm listening to the preamp now-sounds clean. I will then look for the cause of the right channel DC offset and eliminate the audio coupling capacitor.

Good progress this weekend! Thank you again for your assistance!!

Cheers,
Dan