Hi,
Thanks, that's the sort of answer i was looking for. PSU is a 36V Switch mode wallwart, single clcrc filter to 32V, one lm7824 on top of a bypassed led and 47uF cap. Last a rc stage 10R/1000uF. per channel.
I know, heresy but funds are tight and i had to use what i had. The 10R should isolate the 1000uF enough i think and that's an elna silmic II. the b1 uses a single lm317, bypassed devider.
Joris
Thanks, that's the sort of answer i was looking for. PSU is a 36V Switch mode wallwart, single clcrc filter to 32V, one lm7824 on top of a bypassed led and 47uF cap. Last a rc stage 10R/1000uF. per channel.
I know, heresy but funds are tight and i had to use what i had. The 10R should isolate the 1000uF enough i think and that's an elna silmic II. the b1 uses a single lm317, bypassed devider.
Joris
Those circuits had been voiced with the first gen simpler shunts on slower high biased TO-247 Mosfets that contributed oomph. So they may need some re-tuning with different PSU. Especially if SMPS based.
Only make sure on the scope there isn't any switching frequency residue finding its way to the phono's rail or ground because PSRR is almost null in such circuitry. That would decidedly thin it out. That's a noise pollution first subjective effect. Line filtering done carefully but switching noise can couple like electromagnetic signal to an antenna too.
Also if there is path or wiring distance between the second stage's output point and the buffer, stick a 100Ω inline isolation resistor at the output point. Q2's drain node in those schematics.
Let us know how tuning goes on and stay safe, best of health.
Only make sure on the scope there isn't any switching frequency residue finding its way to the phono's rail or ground because PSRR is almost null in such circuitry. That would decidedly thin it out. That's a noise pollution first subjective effect. Line filtering done carefully but switching noise can couple like electromagnetic signal to an antenna too.
Also if there is path or wiring distance between the second stage's output point and the buffer, stick a 100Ω inline isolation resistor at the output point. Q2's drain node in those schematics.
Let us know how tuning goes on and stay safe, best of health.
Hi,
Yes, i know the psu is not nearly as good as ccs shunt. I did scope various points but no clear signals up to 10mHz. The B1 has a 1k gate resistor after the volume pot. Should that not suffice for the output series resistor? There's about 15 cm of wire per channel.
Edit: I do use a coupling cap, 4,7uF, at q2's drain, 1m resistor to ground.
Anyway i will try and see. Probably later this week. For now it's spinning records and quite nicely. I like it! this was build for the second setup in the living room. It is already better than expected.
Joris
Yes, i know the psu is not nearly as good as ccs shunt. I did scope various points but no clear signals up to 10mHz. The B1 has a 1k gate resistor after the volume pot. Should that not suffice for the output series resistor? There's about 15 cm of wire per channel.
Edit: I do use a coupling cap, 4,7uF, at q2's drain, 1m resistor to ground.
Anyway i will try and see. Probably later this week. For now it's spinning records and quite nicely. I like it! this was build for the second setup in the living room. It is already better than expected.
Joris
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That 1K resistor is a gate stopper for B1. It should be best located very close to its gate pin. Without any it oscillates due to wide bandwidth and incoming wiring/layout inductance. But it can also use lower in value when no long interconnects are involved.
Since the distance is 15cm only and you don't see any weird riding waveform on the signal path all should be well as it is.
Since the distance is 15cm only and you don't see any weird riding waveform on the signal path all should be well as it is.
Hi,
Yes, i know what the gate stopper is for. Just did not see the use of an extra resistor in that line. Stray capacitance is low with the short wires.
Hooked up the scope and a function generator this morning. There is a very low 2mV frequency at about 10Hz but that is probably residual as it is measurable at any point. No other signals to be seen. Even with 1V/1MHz input for the line stage right next tot the phono inputs, no signal is measurable in the phono stage. max resolution about 0.2mV.
So i guess it comes down tot riaa components being slightly off. Thanks for the design and advice!
Regards,
Joris
Yes, i know what the gate stopper is for. Just did not see the use of an extra resistor in that line. Stray capacitance is low with the short wires.
Hooked up the scope and a function generator this morning. There is a very low 2mV frequency at about 10Hz but that is probably residual as it is measurable at any point. No other signals to be seen. Even with 1V/1MHz input for the line stage right next tot the phono inputs, no signal is measurable in the phono stage. max resolution about 0.2mV.
So i guess it comes down tot riaa components being slightly off. Thanks for the design and advice!
Regards,
Joris
Nice that your build is clean so to know where to aim for. In other words for tuning it. That second stage output resistor suggestion was just in case there was a damping problem directly at the second stage's output. Because it was originally made with its own single JFET buffer tightly put together. Not tested with an external buffer back then.
I am only very cautious with SMPS and phonos because I have even witnessed 20Hz-20kHz FFT clean as a whistle on the bench with such PSU and an op-amp 60dB phono (high PSRR chips) but when on the actual system it turned very audibly hissy. Replaced with linear PSU with nothing else touched, total silence. Those hundreds of kHz switching frequencies find crazy ways to couple back sometimes.
I am only very cautious with SMPS and phonos because I have even witnessed 20Hz-20kHz FFT clean as a whistle on the bench with such PSU and an op-amp 60dB phono (high PSRR chips) but when on the actual system it turned very audibly hissy. Replaced with linear PSU with nothing else touched, total silence. Those hundreds of kHz switching frequencies find crazy ways to couple back sometimes.
I am almost done with my boards and transformer (Antek) arrived yesterday.
I have a question about the 100 ohm resistors included in my kit. I have the big kit, with all the premeasured/matched parts.
The BOM listed them accordingly:
(RX-1): 71-RN55E100 (Mouser #) RN-55E1000BB14 (Manuf. #) .1%
(R20): 71-CMF55100R00BEEB (Mouser #) RN-CMF5500R00BEEB (Manuf #) .1%
(R21): 71-CMF55-D-1001R (Mouser #) CMF5501R00DHR6 (Manuf #).5%
(R22): 71-CMF55-D-1001R (Mouser #) CMF55100R00DHR6 (Manuf #).5%
What came is:
4 pieces of :
Bag marked "0.1% signal resistors" (4) marked on body CMF100 .1% T9 1850
Bag marked "signal resistors" (4) marked RN55C1000F
Am I correct that the .1% CMF100 are for positions RX-1 and R20? and RN55C100F for positions R21 and R22?
I have no doubt I have the correct parts and they are measured correctly, just dont want to mix them and their positions up
Thanks in advance,
Russellc
I have a question about the 100 ohm resistors included in my kit. I have the big kit, with all the premeasured/matched parts.
The BOM listed them accordingly:
(RX-1): 71-RN55E100 (Mouser #) RN-55E1000BB14 (Manuf. #) .1%
(R20): 71-CMF55100R00BEEB (Mouser #) RN-CMF5500R00BEEB (Manuf #) .1%
(R21): 71-CMF55-D-1001R (Mouser #) CMF5501R00DHR6 (Manuf #).5%
(R22): 71-CMF55-D-1001R (Mouser #) CMF55100R00DHR6 (Manuf #).5%
What came is:
4 pieces of :
Bag marked "0.1% signal resistors" (4) marked on body CMF100 .1% T9 1850
Bag marked "signal resistors" (4) marked RN55C1000F
Am I correct that the .1% CMF100 are for positions RX-1 and R20? and RN55C100F for positions R21 and R22?
I have no doubt I have the correct parts and they are measured correctly, just dont want to mix them and their positions up
Thanks in advance,
Russellc
I am almost done with my boards and transformer (Antek) arrived yesterday.
I have a question about the 100 ohm resistors included in my kit. I have the big kit, with all the premeasured/matched parts.
The BOM listed them accordingly:
(RX-1): 71-RN55E100 (Mouser #) RN-55E1000BB14 (Manuf. #) .1%
(R20): 71-CMF55100R00BEEB (Mouser #) RN-CMF5500R00BEEB (Manuf #) .1%
(R21): 71-CMF55-D-1001R (Mouser #) CMF5501R00DHR6 (Manuf #).5%
(R22): 71-CMF55-D-1001R (Mouser #) CMF55100R00DHR6 (Manuf #).5%
What came is:
4 pieces of :
Bag marked "0.1% signal resistors" (4) marked on body CMF100 .1% T9 1850
Bag marked "signal resistors" (4) marked RN55C1000F
Am I correct that the .1% CMF100 are for positions RX-1 and R20? and RN55C100F for positions R21 and R22?
I have no doubt I have the correct parts and they are measured correctly, just dont want to mix them and their positions up
Thanks in advance,
Russellc
Russellc, you are correct with the positioning.
Signal resistors are less important for precision than the .1% ones.
I have had to make a number substitutions based on some availability issues with some Dale resistors. So some CMF became RN resistors. Possibly the other way around. I am quite certain the part substitutes will have very little influence on expected house sound. If there was any doubt, I would consult Salas on the matter.
Thankyou, I figured that whatever part was substituted is measured, matched whatever, I knew some were more critical than others. What I really know, is that given a chance to mess up, I am liable to.
Now for a case...well, I will try it caseless at first fire up on my pizza board.
Thanks,
Russellc
Now for a case...well, I will try it caseless at first fire up on my pizza board.
Thanks,
Russellc
![IMG_4814[1].JPG](/community/data/attachments/828/828314-4cadf4d1025558661016cb299f25244d.jpg)
They are all close, but I didn't know if matched by position, as you pointed out, or by the board. Looks like position, Q1 to Q1, etc.
I will wait for Salas for last advice, probably your answer resolved it, (close enough to not matter) but I am prone to trouble with these things!
Russellc
I will wait for Salas for last advice, probably your answer resolved it, (close enough to not matter) but I am prone to trouble with these things!
Russellc
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