What causes grainy sound

[indra1]

... I assumed they are very low bandwidth.

Vladimir was talking about the 1T910A Ge PNP 35W 30MHz ft.

 

[picowallspeaker]

I had a very good sound from two simple projects that Rockmandrake published along here 10 years ago. AD 147 or similar...
Being very old transistors, they deteriorate very quickly for the reason of the white powder inside them that changes over time.

 

[mountainman bob]

My_Ref Fremen Edition - Build thread and tutorial. The schema is in the google drive link of the first post. May be you can find the PCB somewhere on ebay or something.

Thanks John,

And thanks to everyone for the help in trying to figure things out.....whether or not the differences I hear are only my imagination they are there none the less.......maybe everyone should enjoy a bit more imagination?

 

[mountainman bob]

Bob also mentioned slew rate, but I think JC likes high slew rate in his amps, so it is not because of the lack of it. High slew rate tends to increase the overshoot factor. But from Stereophile measurement I could see that the Parasound has so smooth squarewave. May be JC tried to make this smooth (for marketing purpose) and the effect is something that Bob didn't like. From Bob description of the sound, I thought there is possibility that base resistors have been aggressively used. But if we follow the logic that all amps sound the same, it could be just Bob's ears

Here’s a pic if that’s the same one.....

https://www.stereophile.com/images/1115PHalofig14.jpg

This is description from Alterman audio.....

“FETs. His design uses balanced push pull complementary circuits. Dual JFETs are used for the input section. FETs are Field Effect Transistors which combines many of the sound characteristics of tubes with the advantages of transistors. Matched MOSFETs are used in the driver stage.
The output stage uses 12 high voltage, high current bipolar transistors”

Here is a link to the stereophile measurements......

Parasound Halo Integrated integrated amplifier Measurements | Stereophile.com

Anyone see anything that would equate with what i’m hearing?

Thanks,
Bob

 

[VladimirK]

Vladimir was talking about the 1T910A Ge PNP 35W 30MHz ft.

Output resistance 0, 075 R with 1t910a, and 0, 018 R with 1t813a

 

[analog_sa]

Looking at the datasheets only the 910 has a a spectacular Ft. The 813 sheet mentions only the switch off delay which is probably irrelevant for linear applications.

The 813 appears a lot easier to source but is it worth it? Big sonic difference to the 910?

 

[VladimirK]

Looking at the datasheets only the 910 has a a spectacular Ft. The 813 sheet mentions only the switch off delay which is probably irrelevant for linear applications.

The 813 appears a lot easier to source but is it worth it? Big sonic difference to the 910?

Sound is a bit more detailed with 910, but their reliability is not so good for se operation. Also transistors forming output triplet are germanium. Ge has less base region resistance in chip, theirfore less output resistance

 

[VladimirK]

Ft for 813 should be around 10MHz, by analogy with gt806 transistor. 813 has two 806 chips in parallel.

 

[johnego]

Vladimir was talking about the 1T910A Ge PNP 35W 30MHz ft.

1T910A. Does T stand for T-rex? Vladimir knows good stuff, I think the Ge I have access to won't be half close. BTW, I need to make a commitment now not to waste my time thinking about Ge anymore...

 

[N101N]

The fastest and purest sound was with Ge output amp.

Ft does not denote operating bandwidth. Operating bandwidth has many mysterious dependencies and it cannot be measured. Ge output transistors have low bandwidth thereby high distortion due to high voltage and current gain, huge Cob, low intrinsic impedance and poor electron mobility. The Ciuffolli Power follower is a bad design with a ridiculous power supply. Also, it is anything but single-ended. Some people develop an admirable capacity to fool themselves.

 

[analog_sa]

I'll skip the philosophical questions this last post prompts, but why is the obviously single ended follower be "anything but single ended"? Saying it is "anything but a follower" would certainly be less contentious.

 

[N101N]

It is obviously not a single-ended, but an arrant balanced topology (180° phase relationship, output not referred to ground). Nor is it a follower in any sense (follows excitation poorly). The author himself served up a muddy circuit description.
The expression "single-ended push-pull" does not make sense either.

Philosophical questions are accepted.

 

[Bigun]

Ft does not denote operating bandwidth. Operating bandwidth has many mysterious dependencies and it cannot be measured. Ge output transistors have low bandwidth thereby high distortion due to high voltage and current gain, huge Cob, low intrinsic impedance and poor electron mobility. The Ciuffolli Power follower is a bad design with a ridiculous power supply. Also, it is anything but single-ended. Some people develop an admirable capacity to fool themselves.

It's be said before on this forum - the best sound ALWAYS comes from something unusual, over simplified, and especially using obsolete components or materials. And the poor sounding options are those that are engineered based on modern current production components and materials, and especially if employing SMD ic's used for volume production.