Simplistic NJFET RIAA

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Joined 2006
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What material is the resistive element in the precision Vishay pot? Wirewound?

Loading Riaa on upper side you may see in SRPP like with Nikitin solid state phonos. Not that unrelated to an anode Riaa on a pentode. Well, high impedance on one hand adds more noise and EMI susceptibility, also not so good in driving the second stage, but results to smaller capacitors physically on the other. Maybe the noise performance of the pentode as an input element already sets an SNR limit that preserving the head amp gain is preferable in a certain design. For headroom with MM and relying on a high ratio SUT for MC. Only the designer can give the whole story of his choices in reference to a concept he had.

Yes, wirewound.... a revelation IMO

Thanks for the comments about te circuit :)
 
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Where you install that? At back panel near the RCA and paralleling it? Wirewound are considered good in small signals in general, still maybe you were able to home in at load values that you did not have in Texas Z-Foil and that contributed somewhat to your liking? Or your impression are VS a B-Foil pot?
 
That's all very well that it honors first impressions still. If to install in the TT see to make nice little shield cans for it. Did you listen at normal to high volume enough? What is the system it plays in? (Sorry if I had asked before and I don't remember).

Yes, and it will be improved further with some better caps when I put in a new order at partsconnexion. I´m considering how to make the box at the moment. It´s a tight fit, so I think I might just make a small framework and shield it with foil.

My system is in the middle of a huge makeover, but right now the chain is:
Goldring Eroica lx
Linn lp12 with rb300
Folded simplistic
Passive doxa preamp (strangling a lot of the dynamics)
Electrocompaniet aw220
Dali Mentor Menuet

I also have a complete dcb1 in my drawer (untested yet), and I´m currently soldering my f5 together. I´m also getting an Ortofon rondo bronze in some weeks. In the atumn I hope to have the dcb1 and the simplistic psu in one box, with remote triggering to the f5. Before all that is in place, I have to make some compromises so the stereo is user (girlfriend) friendly.
 
I´m building the f5 with 220ohm feedback resistors to have some extra gain. I have though about this problem, but I´ve decided to try and see. I live in a small apartment with poor insulation to the neighbors, so I really don´t have any need for a loud system. Thats why I have the small, inefficient speakers in the first place.

Thanks for the advise anyway! I´ll be sure to send you my thoughts if I´m only getting whisper levels here. :)

What preamp would you recommend? I know there are rediculous numbers of designs out there, but thats why I´m asking.
 
diyAudio Chief Moderator
Joined 2002
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In case the levels will be enough for you the DCB1 will restore some dynamics in place of your now passive controller and you will know soon since you got one waiting in the wings but I still think some gain should allow better dynamic expression. You could try with something simple to make and evaluate.
Recommendation...hmm maybe the BA-1 front end so to keep in the PASS theme and there is an easy to get board on the DIYA store. P-BAGS-1V20 - Burning Amplifier Gain Stage for BA-1 & BA-2 (Requires bias boards and output stage; Makes 2 channels; Rev 2.0) - Pre-Amplifiers - PCBs
 
Ok. I´ll just have to wait and see. The f5 is a p2p build, so its not going that fast.
We are heading off topic here, but just one more question for you (for now :)):
The signal cable I´m using in the f5 has two internal wires plus a shield. The shield is usually connected floating in the "source" and not connected at the end. How should I do this in the f5? Only connected to signal ground in the amp and not on the chassis rca?

Or should I just use a standard coaxial cable?
 
Member
Joined 2006
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Where you install that? At back panel near the RCA and paralleling it? Wirewound are considered good in small signals in general, still maybe you were able to home in at load values that you did not have in Texas Z-Foil and that contributed somewhat to your liking? Or your impression are VS a B-Foil pot?

Vishay 1280G trimming potentiometers: Bulk metal foil pc mount type (5kohm)

I mounted the new ww pots near the output rca, with parallel connections.

I am using exactly the same load as before, the sound now presents more attack.
With the bulk metal sound is more gentle with better integration and fluidity but these are difficult ot get and expensive.
 
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Joined 2009
Paid Member
Vishay 1280G trimming potentiometers: Bulk metal foil pc mount type (5kohm)

I mounted the new ww pots near the output rca, with parallel connections.

I am using exactly the same load as before, the sound now presents more attack.
With the bulk metal sound is more gentle with better integration and fluidity but these are difficult ot get and expensive.

Ricardo I bought mine Vishay 1280G to Michael Percy Audio USA:)
 
......................The signal cable I´m using in the f5 has two internal wires plus a shield. The shield is usually connected floating in the "source" and not connected at the end. How should I do this in the f5? Only connected to signal ground in the amp and not on the chassis rca?

Or should I just use a standard coaxial cable?
Use the shielded twisted pair.
The cores carry the Signal Flow and Return.
The Shield gets connected to the Source Chassis and connected via a small ceramic cap (smd1206) to the Receiver Chassis.
 
Its deeper blue in real life, something like blue-black-green. Because the board is thick. When some direct light hits, it opens up in tone. The sinks will be designated as the 1.5inch height model to match the towering electrolytics and be heftier. Black gives more contrast. Blue blends nice. If it was PRP resistors and black connectors it would suit black better. Your call guys, just vote.

green
 
WOW Niko... amazing....!!!!

If you need any help fast, feel free to whip my @$$...

You have my soldering iron, my scope and my bow...

GvjbSSE.jpg
 
hi all,
finally after +1 year MC gain stage with Azur 540 I've made ptp Salas RIAA, MM version with buffer. Still not in the box and no listening yet, I think the hum is bit high, managed to get it down a bit. measured output with Visual Analyzer. Supply is Salas shunt reg with 5 leds.

opa-T-salas-riaa1.jpg

opa-T-salas-riaa2.jpg

njfet-riaa-1KHZ-1a.jpg

Is this quite normal? what is the average noise w/o input signal, got it 23mV rms with DVM. Advice to get hum down is appreciated, looking forward to listen :) and many thanks to Salas