Valve Itch phono

[stajo]

...Still its testing

True. Jumping ahead in my dreams thinking of possible chassies solution before I have a working solution. I can always plug 4 SSHVs on the bench. Have two, can solder two more. Then switch to two and maesure.

 

[stajo]

Hehe. Still laughing of your experts analysis of Accept as Wide band noice. I wonder what Udo Dirkschneider would have to say about that

 

[Salas]

Alright, I was a bit over. Its not Disorder or G.B.H

 

[merlin el mago]

Its OK for the DL-103R bcs its 18-19 Ohm for real so the 977 primary loading is very near.
59dB total will give 220mV. Not for a buffer preamp.

BTW the Jensen JT44 at 10KHZ square before and after Zobel termination on its secondary.

Jensen input impedance typical 430 ohms, do you use 6K81 + 200pF accross the secondary?
BTW I have a quote from Jensen JT-44K-DX 1:10 Step-up Transformers $233.47 USD including shipping but first I nedd to sell my Partridge.

That price is for a pair or each?

6K8 + 200pF dulled the leading edge too much for me. I ended at 100pF polystyrene for the picture I posted. But this is a test with longer cables so its possible to be optimized at 130-150pF in a build. And there is ear check in the end for each one's cart and phono.

Finally I bought the Jensen, meanwhile I'm waiting to arrives, with values for RC filter 6K8 + 100pF or I use the gen + scope with 10K square wave to adjust?

 

[Salas]

Great, I hope it was on a good price. Me I used scope and gen at 10kHz and 20kHz. But 6K8+100pF I found is a good start.

 

[merlin el mago]

Not as cheap as yours, 154$00 USD the pair.

 

[Salas]

Second hand?

 

[merlin el mago]

Yes.

 

[Salas]

They look like new apart from the soldered before cable ends, they are going to sound nice for stepping up the naked 103R you got.

 

[merlin el mago]

Thanks, let's see how well performs in your Itch

 

[Salas]

Let us know very soon. Start with no lower C in RC than 6k8+100pF.

 

[merlin el mago]

OK I will start with no lower than 6k8+100pF & I will let you know the scope results.

 

[Salas]

 

[merlin el mago]

Arrived the Jensen's, time to measure.

 

[merlin el mago]

I guess you use sinus waves?

What are you looking for, the same curve only difference gain?

With 200pf the curve seems equal with 10 & 20KHz, is ok?

 

[Salas]

Square waves. Looking to compensate for no overshoot. Before any RC, after RC:

 

[merlin el mago]

Thanks for the pics, very illustrative.

 

[Salas]

You measure (scope) on Jensen secondary. Feed its primary with 10mV RMS.

 

[merlin el mago]

OK I will measure with my DVM.

 

[stajo]

Salas I assume you did but sometimes those overshoots doesnt sound as bad as they look. What was the difference in sound to your ears? Calmer top? Did you give ony a resistor a goood try?