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Old 24th April 2009, 07:32 PM   #1691
Salas is offline Salas  Greece
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Prefer the lowest Idss for Q5. If you have a couple of GR 4-5mA, even better. There is a reason. The lower the idss, the lower the pinch off, and more the breathing space under Vbe. But we don't want too low, so to keep the Zener working strong enough.
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Old 25th April 2009, 04:41 PM   #1692
RCruz is offline RCruz  Switzerland
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Hi Salas

I am using 8mA jfets on Q5 (below the zener)... should I replace those by some 4-5mA ?

Ricardo
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Old 25th April 2009, 06:05 PM   #1693
Salas is offline Salas  Greece
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Yes, you can save the stronger ones for audio like the RIAA. Maybe you have some low ones that don't batch with the others, and can serve better as shunt's Q5s.
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Old 27th April 2009, 08:51 PM   #1694
RCruz is offline RCruz  Switzerland
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Default More voicing....

Hi Salas

After replacing the signal cord between 101pre and 103amp with a specially built with silvered 5 pin din and mogami wire, I noticed a good increase in detail.

This detail is welcome in the CDP and the Tuner but the Riaa now sounded a little forward and piercing in the highs.

I reinstaled the stock cable and althou I had no edgy sound, I really missed the added detail.

So I decided to reinforce the bypass on riaa C3 and my first impressions are favorable but I am afraid to be altering the riaa curve.

I have the following values:

C2 = 47.36nF (as measured with the DMM)
C3 = 16.23nF (15720 + 330 + 120)pF

C2/C3 = 2.918 (Looks good)

Am I creating some kind of distortion or time skidding? (The resistors are 47k and 6k8 kiwames 1%)

Acording to http://www.beigebag.com/case_riaa_5.htm I should reduce the resistor values to 46150 and 6720 ohm to reach optimum values but that is not practical.

Ricardo
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Old 27th April 2009, 11:25 PM   #1695
Salas is offline Salas  Greece
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Our Riaa values include the first stage output impedance and second stage loading. Also they are judiciously voiced a bit, so don't go with calculators. In general, I don't think that is a good idea to tweak basic Riaa tonality just to allow for interconnects that you will change again maybe in the future or they will settle softer in a while etc.

Why don't you readjust your VTA first? It is possible that the silver new connector part is a bit over the top for detail, so it could be counteracted that way.
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Old 28th April 2009, 03:37 PM   #1696
RCruz is offline RCruz  Switzerland
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Thank you Salas.

I will now rollback this mod.... I noticed odd effects (less stage width and unconfortable mid range).

I will verify VTZ and also the cart loading.

Ricardo
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Old 28th April 2009, 04:23 PM   #1697
RCruz is offline RCruz  Switzerland
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Just removed the aditional 120p cap on C3 and the stage widened and got taller instantly.

The odd mid freq effect also vanished.

I love the über detail...

Ricardo
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Old 29th April 2009, 07:39 PM   #1698
RCruz is offline RCruz  Switzerland
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The riaa is so detailed I can easily set up VTA. Why did I not remenber this in the first place ?

I lowered the arm .3mm and all the harshness went away.

Once again I should have known better

The sound is now better than ever.

I am quite sorry to have reported my previous mod that should never have happened. (Feeling like a )

Ricardo
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Old 29th April 2009, 08:05 PM   #1699
RCruz is offline RCruz  Switzerland
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Default Nichicon

Today I received from China two 15000uF 63V Nichicon (M) labelled as Marantz.

I bought them believing these were Gold Tune KG caps but the label only states "Marantz"

The size does not appear on nichicon site but they are heavy and look great.

Only 30 minutes after replacing the 10.000uF BHC by these, I noticed lower noise floor and much better bass......

Outstanding sound

Ricardo
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Old 29th April 2009, 08:09 PM   #1700
Salas is offline Salas  Greece
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Thanks Ricardo for your mods quest reports. Adds much value for those making the phono. I hope that Kent will conclude the practical part with making and posting the final PCBs too.
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