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I think the OPA164x devices are generally superior to the LM4562, but the patter’s PSRR is superb so I use it as a reg. As a GP audio amp stage, it has been shown to have many flaws. Quite why TI haven’t sorted it. Might be they know it’s days are numbered and the OPA devices are better.

4 V RMS out suggests +- 7.5 V rails, not 5 V. There are quite a few PGA products that use these voltages so my guess is one of these is buried in there somewhere, although looking at the main analog board I see lots of very small 8 pin and 6 pin devices.

If you want a decent preamp and don’t want to pay a lot of money for it, you are going to have to assemble the PCB’s yourself and if it has some of the features on this preamp, code as well. Then there’s the engineering in the housing (drill, machine, anodise etc). It’s a EU product, so will be...

I have only unbalanced inputs (6 off) two unbalanced outputs, one unbalanced record output and one balanced output on my preamp. The balanced input thing is overrated IMV. The 193 mW into 32 ohms is disappointing - there are lots of nice driver chips that are capable of 5 or 10x that power level.

Here is an all active RIAA design with very low measured noise and distortion Part One https://audioxpress.com/files/attachment/2735 Part Two https://audioxpress.com/files/attachment/2736

I don’t really have a problem with ‘gentlemen’s club’ amps like the AudioNote. Personally I would never spend the $6k asking price on one, but who am I to judge. If someone gains pleasure from it, good for them. I guess it’s like a good bourbon vs a 15 yr old single malt. The problem I have is...

If people believe there is a man in the sky they have to obey in order to avoid hell . . . I suppose they’ll believe a 10W AudioNote amp featuring 2% distortion ‘sounds magical’. Do a search on recent Stereophile reviews

I’ve done a DC Blocker plus soft start here https://hifisonix.com/projects/soft-start-dc-blocker-for-mains/ I had a YouTube video up showing the effectiveness but took it down since I want to reshoot it.

For FR anything better than 0.3 dB RIAA conformance 20 Hz to 20 kHz should be considered good. What is important is that at >>20 kHz the response is well behaved and does not exhibit any peaking. Note that most MM carts exhibit some peaking due to the mechanical behaviour of the stylus and the...

There are two basic approaches to phono smp design 1. active/passive. With this approach, you amplify the signal from the cartridge and then feed it into an equaliser network. 2. all active. With this approach, the equalisation is applied around the main gain stage Designers have their...

Seems to me this might be what’s going on here:- 1.The loop gain is VERY high (rough guess 100 dB or more) and the multi-pole compensation suppresses distortion in the audio band up to 20 kHz to very low levels 2. This will also provide very good in-band IMD performance which is clearly evident...

That’s excellent. But the review graphs here don’t seem to show that. Might be Amir needs to add a 19+20 kHz IMD test. I would recommend that for any amplifier - whether class D or linear AB etc

I was commenting on the shape of the distortion curve not how the feedback works. That the Hypex amp use multi-pole feedback compensation is well documented. In the distortion graph shown it bulges between c 7 kHz and HF and espec on the higher order harmonics. One of them is at -80 dB which is...

Given the HF distortion profile, I suspect the two tone IMD results won’t be good. Getting amplifier mA to show good distortion at 1 kHz is relatively easy, but it gets harder at HF. -110 dBr full 2 tone output power would be a good result.

The HF distortion profile is more like that of a zero global feed back amp. Simple question: why is this? A two tone IMD test will expose any inherent HF non-linearity and does not require bandwidths of >21 kHz since the intermod components are folded down into the audio band.

By any measure, the HF distortion on this amplifier is very high. I’d like to see a 19+20 kHz IMD test.

Domestic speakers are designed so that the response tips up by 1-2 dB in the lower octaves.

I am struggling to understand how a review methodology that rates products primarily on measurements can measure the KEF LS50’s, get superb results and then give a ‘not recommended’ rating. Is this a case of ‘objectivist fantasy vs subjective reality’? I‘ve had a pair of these since 2017...

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