This is the datasheet I used:
http://www.lite8.com/download/2SC1845.pdf
....Or should I have typed 2pF?
http://www.lite8.com/download/2SC1845.pdf
....Or should I have typed 2pF?
"Which datasheet do you wanna use today" 
Cob looks like a nice straight line in that NEC datasheet, unlike the others...
Here's what I used:
Black trace is the ON Semiconductor datasheet for the BC560C, and those are the parts that I actually used.
Red trace is from Fairchild KSA992.
Blue trace is from Fairchild BC556..560.
Cob looks like a nice straight line in that NEC datasheet, unlike the others...
Here's what I used:
Black trace is the ON Semiconductor datasheet for the BC560C, and those are the parts that I actually used.
Red trace is from Fairchild KSA992.
Blue trace is from Fairchild BC556..560.
Attachments
Hi everybody.
I read this topic up and down and need just to understand a couple of things,
lots of info to process..... for my brain.
I wonder first, as it looks like it has riaa equalization in the middle,
does it also need subsonic filter, ?
been many different disscusions about this.
also about the transistor choice, I can actually use bc550c /bc560c or 2SA1316 and 2SC3329 or bc337/bc327/ or the 2SC1845 / 2SC992.
I will use a ortophon MM with
Internal impedance, DC resistance
1 kOhm
Internal inductance
580 mH
Recommended load resistance
47 kOhm
Recommended load capacitance
200-400 pF
I appreciate all help I can get,
best regards Niklas.
I read this topic up and down and need just to understand a couple of things,
lots of info to process..... for my brain.
I wonder first, as it looks like it has riaa equalization in the middle,
does it also need subsonic filter, ?
been many different disscusions about this.
also about the transistor choice, I can actually use bc550c /bc560c or 2SA1316 and 2SC3329 or bc337/bc327/ or the 2SC1845 / 2SC992.
I will use a ortophon MM with
Internal impedance, DC resistance
1 kOhm
Internal inductance
580 mH
Recommended load resistance
47 kOhm
Recommended load capacitance
200-400 pF
I appreciate all help I can get,
best regards Niklas.
Hi Niklas,
which Ortofon cartridge do you intend to use with your SUPRA?
From another board I do know of some issues with too high input capacitance that cannot be handled by a few distinct cartridges. So make sure that your phono cables don't have a too big addidional capacitance. Remember that the SUPRA preamp is intended to be used primarily with MC, not with MM cartridges.
Best regards, Uwe
which Ortofon cartridge do you intend to use with your SUPRA?
From another board I do know of some issues with too high input capacitance that cannot be handled by a few distinct cartridges. So make sure that your phono cables don't have a too big addidional capacitance. Remember that the SUPRA preamp is intended to be used primarily with MC, not with MM cartridges.
Best regards, Uwe
ortophon 10
Hi,
I was supposed to use ortophon 10 with a dual 505.
so are there another diy ready with pcb print somethere that very good. ?
Hi,
I was supposed to use ortophon 10 with a dual 505.
so are there another diy ready with pcb print somethere that very good. ?
I've had a look at the schematic for the supra 2.0 now. Since the input is terminated with 100pF and 47k, it's probably meant to be used with MM systems. The design comprises of four non-inverting LT1028 working into an inverting buffer with a total gain of 45dB at 1kHz, followed by a three-stage active RIAA network including a 10Hz and a 50kHz pole. The pcb is solely surface mount and the four other opamps are LM837 in a single package. Not much to complain so far, since all parts are standard E48 values and thus easily available. Overload performance should be as good as it gets, since all the gain is in the first stage with the others basically being buffers only. Reducing the overall gain would yield some more headroom (I've opted for 35dB instead of 45dB), but that's another story.
Of course I had to simulate the circuit with a noiseless inverse RIAA network and the cartridge values of 410R and 480mH, and here the simulator seems to confirm my concerns. See the results attached. With the LT1028 model for the parallel input quad and my NE5534A model for the other opamps, the output noise in the range of 20Hz to 20kHz integrates to almost 830uV. Using my NE5534A model for all eight opamps, the result is certainly a lot better with an RMS value of only 115uV! Using the NE5534A model from TI's website the result is even better still.
The sim might not hold true in the real world (the absolute values certainly won't), but if I were the inventor of the supra 2.0, I'd certainly get myself some NE5534A and pop them in there to be sure - they're not that expensive after all
"my NE5534A model" is simply the UniversalOpamp2 of LTspice with the following model parameters:
Avol=1Meg GBW=10Meg Slew=9Meg
ilimit=35m rail=2 Vos=0.5m phimargin=45
en=3n5 enk=30 in=400f ink=1k Rin=100k
The last line is most relevant for noise simulations, with en and in resembling the datasheet values for voltage and current noise, respectively. enk and ink resemble the frequency knee where the shot noise takes over; I've chosen them empirically to match the graphs from the datasheet.
If you take into account A-weighting or ITU-R 468 weighting, you'll probably find that a single NE5534A outperforms four NE5534As. The input stage of an NE5534A appears to be biased quite close to the noise optimum for typical moving-magnet cartridge impedances.
Anyway, I read about the Supra 2.0 circuit in the July/August edition of the Dutch version of Elektor. It is clear that the designers underestimated the effect of the equivalent input noise current and the cartridge inductance; in fact all their measurements are with a source impedance of either 0 or 560 ohm. According to my calculations, even a single TL071 could noise-wise easily outperform the Supra 2.0 for typical moving-magnet cartridge impedances.
In any case, I've sent Elektor an e-mail with the calculation and with the advice to only use the Supra 2.0 with moving coil cartridges, or to replace the input op-amps with FET op-amps like the OPA134 or the OPA132.
Last edited:
test results.
Hi, I can confirm that yesterday,
i tested my Riaa and the data is the same
it follows the RIaa curv as i should and
Got 35 db i gain, with a result of 0.001 thd.
then on my Ortophon I loaded 220pf and had 47k to ground
works really nice.
but i heard that recommended Gain would be like 46db. ?
Hi, I can confirm that yesterday,
i tested my Riaa and the data is the same
it follows the RIaa curv as i should and
Got 35 db i gain, with a result of 0.001 thd.
then on my Ortophon I loaded 220pf and had 47k to ground
works really nice.
but i heard that recommended Gain would be like 46db. ?
I'm curious, too, 'cause I think paralleling that much input devices isn't a good idea w.r.t. Miller capacitance.
Best regards!
I have already mounted this version of 'Supra' and the disappointment was very large, aggressive highs and very flat bass, another director had the same result as me.
I must say that the circuit board was not that of 'scafas' and without questioning the design of Elektor I expect to see the summary of 'maxwell007'.
have you tried to adjust some value of the components in the riaa section?I have already mounted this version of 'Supra' and the disappointment was very large, aggressive highs and very flat bass, another director had the same result as me.
I must say that the circuit board was not that of 'scafas' and without questioning the design of Elektor I expect to see the summary of 'maxwell007'.
the sound of the SLN is very controlled in the bass section but this was well known.
No, I had mounted the values mentioned by Elektor, the capacitors were 1% polystyrene and the metal resistor 1%.
It is possible that it was because of the pcb that I drew, your is very well drawn and it interests me to know the results with this one.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.