Those are really good news.... I will build severall riaa circuits to experiment with different kinds of components
I had a wonderfull experiment with Mouser and parts are arriving today ... way cool
I just downloaded the latest BOM from hesener's post on th GB thread... what is the purpose of R104b R204b resistor with X value ?
these are just to finetune the current of the CCS in the power supply section. In most cases you will not need them, if your power resistors R104, R204 are reasonably good.
typically in shunt regulators you want to set the current at twice the load current, so that you operate well within the sweet spot of the regulator, and that is the case here. So the absolute value of the CCS current does nto really matter much.
but I will leave it to Frans (the PSU designer) to comment.....
Thank you so much.... As you can see, my calculations give similar results to your simulation
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A while ago I recommended micas from Jahre. They also do build to order. I think 1% is no problem. Why not go for them?
http://www.jahre.de/index.php?id=61
http://www.jahre.de/index.php?id=61
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Those are really good news.... I will build severall riaa circuits to experiment with different kinds of components
I had a wonderfull experiment with Mouser and parts are arriving today ... way cool
I just downloaded the latest BOM from hesener's post on th GB thread... what is the purpose of R104b R204b resistor with X value ?
Those are really good news.... I will build severall riaa circuits to experiment with different kinds of components
I had a wonderfull experiment with Mouser and parts are arriving today ... way cool
I just downloaded the latest BOM from hesener's post on th GB thread... what is the purpose of R104b R204b resistor with X value ?
There are 3/4 parts that set the CCS current: Led L110, Vbe Q102 and R104/104b.
The CCS current = ( V(L110) – Vbe(Q102) ) / R104.
Some of these (all
) are a bit imprecise and may lead to slightly different currents in both CCS’s, to adjust these and ‘not needing to change the bulb’ – sorry replace the resistor (and possibly damage the board) an optional parallel resistor was introduced.To make currents in both CCS’s equal, add power
, measure the voltages across the resistors R104 and R204, then (for the side with the highest voltage) calculate the current Ih = Vh / Rh . Then for the side with the lowest voltage calculate a resistor Rl = Vl / Ih. (where h=High side, l=Low side).Next we need to calculate the parallel resistor to introduce, 1/Rx = 1/Rl – 1/Rh.
I hope that this is clear
P.s. http://www.youtube.com/watch?v=Qa_gZ_7sdZg
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Micas can sound stark... I only use them to "top up" and reach optimun values. They match well with larger vaules polypropylenes.
If the 11n are not carefully matched between channels, you might get an audible difference similar to gain difference between cahnnels.
In my Paradise I matched the two channels to better than 0.1%, using 100pF, 220pF caps (in my case, Wima MKS2) as needed (and of course measuring them all) to combine to the perfect value. Similar for the resistors. This took me around 1hr to get it all sorted, but it really is worth the effort.
Perfectly clear... Thank you so much....There are 3/4 parts that set the CCS current: Led L110, Vbe Q102 and R104/104b.
The CCS current = ( V(L110) – Vbe(Q102) ) / R104.
Some of these (all
To make currents in both CCS’s equal, add power
Next we need to calculate the parallel resistor to introduce, 1/Rx = 1/Rl – 1/Rh.
I hope that this is clear
P.s. Blue alert - Red Dwarf - BBC comedy - YouTube
Can we modify the resistors values to "hot rod" the shunt so it works at higher ccs current ?
What do you use to measure such tight tollerances? Or do you just match the chanels?
I would think so too.
This is what I am going to do:
When I will get the boards, I will build them up using standard parts (WIMA/ DALE/ PANASONIC FC) measure, listen and cross reference it with other phono I have.
Then I will upgrade with The custom 11n and 32nF Aura T I have in the house.
If the phono will respond the way other piece of equipment responded, I will let you guys know and who is interested can join a group by for the VCAP CuTFT.
Souds like a plan?
The reason i've been buying RIAA caps (1%) by the 100's and K's over the last +25 years.
http://www.diyaudio.com/forums/soli...ls-blowtorch-preamplifier-35.html#post1285128
Aah, Freak city, my kind of town.
Shame that almost all old Ossi buildings in Berlin are gone, no more demolition club parties.
Radisson Blu Alexanderplatz (beats me why someone who lives right at the ocean, picks an aquarium hotel
)Attachments
There is a difference... It is quite difficult to get a good stable soundstage if you use different resistor, cap values (keeping the same RC number), so I find it very expensive to build a very well matched riaa because I always need to buy 10x times the number of parts needed so I can get almost exact matched parts.
I am experienced in this subject as I have built several passive riaa filters in the past.
I dream about teflons but how much would it cost to have matched pairs with the exact values needed ?
unless you buy them from Parts Conn or direclty from Audience or V-Cap, then you can only buy 2 and precision will be better than 1% ()in my experience most of the time is below 0.5%)
If you know what you want and you know what you need, there is no need for anybody to buy 100s of parts!