How can an audio reviewer mention this? :
" One thing you won’t be able to do with the Tube Box S2 MM/MC is swap out the tubes (not without some difficulty, at least)."
Best Phono Preamps of 2021 | The Master Switch
( see review 5 )
Have you ever used an Allen key? Once you remove the protection from the tube, you can do all the tests you want with other tubes, and when you are satisfied with one, close it!
I think the reviewer did not spend enough time to review, something more significant could have found .....
Have you removed the lid to see inside? Surely not ...
" One thing you won’t be able to do with the Tube Box S2 MM/MC is swap out the tubes (not without some difficulty, at least)."
Best Phono Preamps of 2021 | The Master Switch
( see review 5 )
Have you ever used an Allen key? Once you remove the protection from the tube, you can do all the tests you want with other tubes, and when you are satisfied with one, close it!
I think the reviewer did not spend enough time to review, something more significant could have found .....
Have you removed the lid to see inside? Surely not ...
Attachments
Just light the tube up with no B+ voltage or anything else and just have the op amps do the job. Charge tube prices. Heck, don't even put an HV supply in the sumbitch.
" The Pro-Ject Tube Box S2 boasts fully discreet circuit design without OpAmps "
That's exactly what the manufacturer's description says ......
Which causes me great confusion ....😕
I always thought that a "discrete" circuit did not use IC or OpAmps, only TR's ......
Tube Box S2 – Pro-Ject Audio Systems
That would have been an accurate review !
The ECC83s may be running in 'starved plate' mode.
This arrangement will produce distortion which may be pleasing to some ears!
Users like to do some 'tube rolling' to see if that makes an audible difference.
Last edited:
I knew it, they couldn't give such a wrong description ..... the
judgment industry is always on the lookout.....🙄
The S2 is a hybrid amp with JFETs doing a pre-gain and then the ECC83s taking care of the rest. Ripe for 'tube rolling'!
And, I may be wrong about the 'starved plate' operation as I read that there is a DC to DC convertor circuit (located between the front panel and the steel partition).
And, I may be wrong about the 'starved plate' operation as I read that there is a DC to DC convertor circuit (located between the front panel and the steel partition).
Last edited:
It is DC to DC conversion.
The 18V DC supplied by the outboard supply is converted electronically to the higher DC voltage (at least 100V) required by the anodes of the ECC83s.
Commentators should not confuse the $400 Pro-Ject Tube Box S2 with some cheap Chinese preamp where the valves are there simply for show!
The 18V DC supplied by the outboard supply is converted electronically to the higher DC voltage (at least 100V) required by the anodes of the ECC83s.
Commentators should not confuse the $400 Pro-Ject Tube Box S2 with some cheap Chinese preamp where the valves are there simply for show!
Last edited:
Here is the S2's product information sheet: https://www.project-audio.com/wp-content/uploads/2018/04/TubeBoxS2-EN.pdf
Note the part that says "Well filtered high-voltage anode supply".
Note the part that says "Well filtered high-voltage anode supply".
Its not rocket science to realize many readers couldn't tell an allen key from a torx wrench and would have difficulty with this - its a sad fact a lot of people have never used even a screwdriver in anger.
My gripe with some audio reviewers is the verbal diarrhea of nonsense they spew out, often corruptly disguising advertizing as criticism, or simply producing meaningless drively adjective soup. ******** baffles brains as they used to say.
Ok, I was quick to ask, because the appliance is powered by an external AC / DC adapter, so there can be no AC inside it. Except for analog audio signals, of course.
For young people and newcomers, I think it is interesting to mention that this process you describe was done with a design called "multivibrator" in car valve radios, raising the battery voltage to that necessary to power the "plate" (here is he usually calls the anode that way) Nothing new under the sun, it's in the basic electronics books. Only now miniaturization makes incredible designs.
PS: I wouldn't call it DC to DC conversion, because it's still DC, I'd call it "DC boost", or something similar.😉
Wikiwand)