Simplistic NJFET RIAA

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Hi Salas

Here you have the latest layout for the riaa. Could you please comment on the locations ?

Centre cap is a 100n FT-3 and below is a 47n obbligato gold. In the output there is a 4u7 obbligato gold.

I am doing it p2p but maybe I will build a pcb for later use.

Can I use 680uF caps on C5 and C6 ?

Regards

Ricardo

I like this layout. Logical, start earthed, straightforward. Of course you can use 680uF. Even for the LEDs capacitor. Panasonic FM at least.
 
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Good.... the 680uF will be BGNx.

Already have a psu with 1 tx double winding 25v 40VA feeding 2 x (full bridge + 15000u Nichicon KH) and two shunts working since yesterday.

The shunts have a led vdrop of 5,7v so I am using 10r for R1.

I am inclined to do not connect the gnd of the psu´s together inside the psu case.... both +v and 0v will travel independent from psu case to riaa case and the only gnd connections will be done inside the riaa in the star earth.

Waiting for XLR 5 pin for the external psu connections.

As for cable I do not know what to use... maybe kimber KWIK-16 !?

Ricardo
 
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Hi salas and all,

"Matching time" and after reading PSGR's excellent construction tips I constructed a test jig for fets and leds (pics will come shortly).
Oh man... :spin: it took me 1 day to find the following pairs (and quads):

for Q1 (0.890, 0.889)
for Q5 (0.871, 0.869)
for Q2 (0.856, 0.856)
for D1-D4 (7.3, 7.32)

in parenthesis are the voltage drop reading of my DMM over a 100R (actually 99R) resistor.

Being in the upper value range for fets and the lower for leds I need your comments just to be sure :)
 
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Shunts ready and tested....
Channel one is ready for testing...:)

Ricardo
 

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diyAudio Chief Moderator
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Temperature is dropping and diy comes alive again. Look what the cat brought in :)

Salas, is the post #133 schematic still actual for the Denon DL-160? I'm aiming for circa 1.5V output. 1K loading I presume?


Congrats on getting the Denon.1k RL works for me, yes. That one linked is good for minimalism, but is bettered for resolution by the Medium MC cascode one. The minimal one gives different sound, more tubey. Its good to try out if you are in the mood, maybe it suits better your system. Still with both circuits, you will never get to 1.5V RMS for 0dB record modulation. Around 200mV with the minimalistic and around 500mV with the 48dB cascode with the DL160. If you will try out the minimalistic, make sure that you got no less than 50k of line input to drive. You can use 100R trimmers instead of the Rs resistors in the minimal one and when with about 7V Vd, you will get about 300mV and 44dB with a good distortion profile. Because the records have strong modulations, the way I have chosen the gains and sensitivities, you get about the same subjective volume for same knob position when using a CDP and the TT. You don't want gain for 0db 1V to 1.5V believe me. I have tried high MC into 55dB gain and I had to back up the volume a lot VS CDP, plus the JFETs pick up a lot of distortion, and unwanted gain noise is added.
 
Congrats on getting the Denon. 1k RL works for me, yes.

Ah, I had that minimalistic schematic wrong. The post #1812 schematic is the cascoded one of course. If the output voltage is on par with the CDP then everything is fine ;)

After the break up with the Gyrodeck my setup consists of a whacked up Lenco 75 on which I try different arm and cartridge combinations. Got good results already with the Stanton 881S on a Hitachi arm. With the Denon came a rather fragile Dual tone arm (in fact the complete Dual was there too). I'm thinking about building an 'all out' version phono with four regulators in a copper enclosure. Would this be wise or do I better keep it simple because of the not so high end turn table? :scratch2:

Came across a couple of 1K tants in the parts bin. Are these the famous Shinkos?
 

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diyAudio Chief Moderator
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Ah, I had that minimalistic schematic wrong. The post #1812 schematic is the cascoded one of course. If the output voltage is on par with the CDP then everything is fine ;)

After the break up with the Gyrodeck my setup consists of a whacked up Lenco 75 on which I try different arm and cartridge combinations. Got good results already with the Stanton 881S on a Hitachi arm. With the Denon came a rather fragile Dual tone arm (in fact the complete Dual was there too). I'm thinking about building an 'all out' version phono with four regulators in a copper enclosure. Would this be wise or do I better keep it simple because of the not so high end turn table? :scratch2:

Came across a couple of 1K tants in the parts bin. Are these the famous Shinkos?

The DL160 goes well with ULM arms too. Its light mass enough, I use it on a mission 774 with no problems, just excellent control. I guess that the Dual is a ULM too?

I suggest you change R2 to 27R because the DL160 is on the low output side of real MM. That will give you 44-45dB. With such gain my volume control tracks near behind CDP on average 33RPM LP. On 45RPM EPs with +6dB more average modulation it is louder than CDP.

Spend first on table and arm. What you have made is already good for much better a TT. The DL alone is gonna give you a glimpse.

No, those are not Shinkoh, those are Chinese (not bad, OEM for UK AN, but not the Shinkoh resolution), still your best for load.
 
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Very nice! Ricardo, in the third picture, what are those boards with the big black caps? Two diodes + C filter?
Thank you !!

The boards have four diodes HEXFRED and the smoothing cap.

The TX has double output windings so this will enable a true double mono setup.

Now I am strugling with the strong and oversized shielded cable.... What lenght should I use to connect this psu to the main riaa case ?

Ricardo
 
The DL160 goes well with ULM arms too. Its light mass enough, I use it on a mission 774 with no problems, just excellent control. I guess that the Dual is a ULM too? Spend first on table and arm. What you have made is already good for much better a TT. The DL alone is gonna give you a glimpse.
Yessir, the Dual 505 mkII has an ULM arm which suits the DL-160 excellent. Lowest notes are missing somewhat impact compared to the heavy platter Lenco/MM but mid and high definition is much better. See what you like about it, I have to confirm this phono is revealing :)

Has anybody perhaps tried this isolator?
 
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With the right TT and arm combination, the DL160 has bass as a strong point too. Play with your VTA a little by changing mats on the Dual, you may fool it out a bit. Also use a downforce gauge for verifying exactly 1.6gm, it balances audibly better if there.

P.S. I haven't used an isolator, but the price is too much for what it is made of, you could DIY one, certainly for higher mass, and VTA adjustable arms though.