Valve Itch phono

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Hehe :D

I recently got rid of the second stage RC filter with very good results. Now both first and second stages run directly commanded by the shunt´s output impedance. (I left an RC on the output buffer so it has it´s own "juice" and does not starve the others).

Sound is much more clearer now and I wonder how it should be with a dedicated shunt for each stage.

There is no second stage RC in the SNJR I think. Maybe you talk prior to 10.12.F0 pdf guide build. The itch does not have one there either.
 
I did a comparison on the second system vs the pearl with lundahl step ups. This has a plain power supply - basically just diodes, cap, 0.47R resistors and cap as the main PS, and then the onboard stuff on original pass boards. The lundahls are set up as 1:10.

In my own mind I had this set as the nicer phonostage pre-itch, but in fairness I had never done a real comaprison either. So this was an A/B between the pearl and itch.

The long an the short is that the itch won pretty much hands down. Like with the ono, the area it was better was in the soundstage - really a holographic one with the itch, but more flat with the pearl. Tone, frequency extremes, dealing with busy passages or sibilance, all pretty much the same, but when you actually sit down to listen between the speakers, well, the itch does very very well.

So just for the record, it seems the itch beats out everything else in the house.


System for reference: zyx r50> terminator type air bearing arm, Teres TT clone, DCB1, tubecad EL84 in triode mode, sachiko horns with low level support from 2 x rel subs.



Fran
 
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If it does not annoy you on 98dB speakers then what more. All in all you gave a very thorough account of the build, the grounding battle, the parts used currently, and the subjective evaluations. I must admit you deserve the title of the master Itcher up to now!:D
 
Itchy-and-scratchy-the-itchy-and-scratchy-show-331158_450_450.jpg
 
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I have been reading with interest about Frans build of the Itch and as I use an Xono clone I thought it would be interesting to build one to do a comparison. The only problem is I have no experience with valves[ tubes] other than building a Curcio Daniel pre in the 1990's and certainly have never done anything point to point. I guess I'm going to have to do a lot of reading and close studying of peoples photo's on this thread.

BTW Fran if I pm you my email would you please send me a copy of the Ono service manual. Thanks Marra
 
Marra, how did you do your ono clone?

Shoot me an email and I'll send you back the ono stuff no problem.

The itch is reasonably easy to build, but if you read my notes back up the thread, you will see I had to fight a bit with hum etc. All sorted now thanks to the excellent help and encouragement here. The major thing that sticks out to me is the high voltages involved. Just need to be extra careful.

Fran
 
OK, so remember back up a bit I did a comparison with my clone of the pass ono? Well, after that I started tricking about with the ono, just really swapping in different caps in certain parts of the circuit. The original caps in 2 out of the 3 cases were cornell CDT caps, the other was a panasonic FC 'lytic.

So after experiments with all the caps I had on hand I ended up swapping these out for Russian MGBO-1 bypassed with wima FKP 10nf (except one set where I used 3.3nf).

Anyway this has improved the sound out of the ono by quite a margin. So I thought it would be a good time to compare again with the itch. I hooked both up tonight to try out.

The ono is much much closer to the itch now, and it would be very hard to tell them apart. However, the itch is a bit tighter on the bass, plus it seems to have a tad more resolution. I say that because some small sounds are easier to hear with the itch.

I am very happy with this result.... essentially I now have 2 really top notch, excellent sounding phonostages - one the itch and the other is now nearly as good, all prompted by the itch!


I still have to get the russian FT3 and K72 caps, and I also ordered some more MGBO for the output caps plus some phillips mkc for bypassing.


Anyway, thought it might be useful information for someone.


Fran
 
looking forward to it!


The thing is..... the itch is a lot easier to build than the ono with a lower parts count. Might be cheaper too.

Have you tried different valves? I've never found that much difference between different brands of the same valve, but I have some 6N2P-ev here to try sometime. I used the ordinary 6n2 because I had a matched pair....


Fran
 
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