Sorry for the schematic to be rotated, it wasn't accepted and I lost detail when trying to resize.
I started off with complementary feedback pairs for all transistors.
I made sure the local feedback loops where very small by placing transistors on both sides and using 805 1k SMD resistors.
Didn't workout though, lots of noise. So I ended up with the circuit as posted.
All capacitors are Rubycon ZL series.
All transistors are 2SC2547E and 2SA1085E, except for the power supply (ZTX960B and ZTX790A).
The 100 ohm resisors for filtering the references are all 805 SMD's on the bottom side.
Riv is made up with 1.5K RikenOhm and 10k DALE RN65C.
The Civ is 2nF Philips KP
All references VRx are TL431's (2.5V) the PNP has two red LED's
I'm using some OPA627 for the DC servo, bit overkill, but had not been using 'm ever since I stopped using opamps as I/V converters. The integrator capacitor is on the bottom side, I used a 100nF ERO KP capacitor. Earlier I tried a Blackgate 0.47u/50V NX-HiQ but that leaked too much, resulting in too big an offset.
Pot R2 is adjusted for 0Vdc, the DC servo catches any drifts between ca. +/-150mV
Pot R1 is adjusted for 0Vdc on the DAC outputs.
I'm using some weird resistor values, just happened to be the DALE's I had available. 180 ohms for the 1st current sink and 820 ohms for the second current sink should work just fine.
R11, R6 and T9 are a cascode on the 2nd current sink, they could be omitted. My simulator tells me it does zip for THD. I had them already in, so didn't bother taking them out.
Finally the sound:
Incredible, finally I prefer my TDA1541A-S2 player above my TDA1543 player. Transparency has increased a lot compared to the single ended version of this circuit (see simple I/V threads).
It is amazing how much detail comes out now
I've got another board, that includes TDA1543 as well, with power supplies, reclocking, Tent XO. Hopefully will have it finished in a couple of weeks.
Is sent Peter Daniel the same boards, hopefully he has got something to add to this thread very soon (I'm quite sure...)
Happy building.
I started off with complementary feedback pairs for all transistors.
I made sure the local feedback loops where very small by placing transistors on both sides and using 805 1k SMD resistors.
Didn't workout though, lots of noise. So I ended up with the circuit as posted.
All capacitors are Rubycon ZL series.
All transistors are 2SC2547E and 2SA1085E, except for the power supply (ZTX960B and ZTX790A).
The 100 ohm resisors for filtering the references are all 805 SMD's on the bottom side.
Riv is made up with 1.5K RikenOhm and 10k DALE RN65C.
The Civ is 2nF Philips KP
All references VRx are TL431's (2.5V) the PNP has two red LED's
I'm using some OPA627 for the DC servo, bit overkill, but had not been using 'm ever since I stopped using opamps as I/V converters. The integrator capacitor is on the bottom side, I used a 100nF ERO KP capacitor. Earlier I tried a Blackgate 0.47u/50V NX-HiQ but that leaked too much, resulting in too big an offset.
Pot R2 is adjusted for 0Vdc, the DC servo catches any drifts between ca. +/-150mV
Pot R1 is adjusted for 0Vdc on the DAC outputs.
I'm using some weird resistor values, just happened to be the DALE's I had available. 180 ohms for the 1st current sink and 820 ohms for the second current sink should work just fine.
R11, R6 and T9 are a cascode on the 2nd current sink, they could be omitted. My simulator tells me it does zip for THD. I had them already in, so didn't bother taking them out.
Finally the sound:
Incredible, finally I prefer my TDA1541A-S2 player above my TDA1543 player. Transparency has increased a lot compared to the single ended version of this circuit (see simple I/V threads).
It is amazing how much detail comes out now
I've got another board, that includes TDA1543 as well, with power supplies, reclocking, Tent XO. Hopefully will have it finished in a couple of weeks.
Is sent Peter Daniel the same boards, hopefully he has got something to add to this thread very soon (I'm quite sure...)
Happy building.
Correct, too much hassle to route it, I just solder it on the bottom side between pin 2 and 6 of the opamp.jean-paul said:
The I/V doesn't care about oversampling or not...zygibajt said:
2SC2240 should do just fine
Peter Daniel said:
Simulation shows 2nd harmonic to increase 8dB and 3rd harmonic to increase 10dB when using BC547B and BC557A.
They are supposedly inferior sounding parts as well; get some 2SC2240BL and 2SA970BL from Jocko, let me know how much he wants for 2*50 pieces
Hi Rudolf,
Excellent, as always.
Did I understand you: you started using a complementary feedback pairs for all transistors but found the option you posted here better? Did you mean literally all? If CFP is used as a signal transistor (T8), I can’t see much point of using T6 at all.
Nice to see the TL431 used as a voltage references for the current sources.
As about the SPICE and distortion, it is possible to get the useful conclusions this way but you’ll hardly simulate the difference in distortion between certain types of transistors. Sometimes the difference shown by various SPICE models for the same transistor is bigger than differences between the various transistors.
Pedja
Excellent, as always.
Did I understand you: you started using a complementary feedback pairs for all transistors but found the option you posted here better? Did you mean literally all? If CFP is used as a signal transistor (T8), I can’t see much point of using T6 at all.
Nice to see the TL431 used as a voltage references for the current sources.
As about the SPICE and distortion, it is possible to get the useful conclusions this way but you’ll hardly simulate the difference in distortion between certain types of transistors. Sometimes the difference shown by various SPICE models for the same transistor is bigger than differences between the various transistors.
Pedja
Yep, I mean what I wrote, there was a CFP (1k feedback resistor) for each individual transistor in the schematic.Pedja said:
Turned out I made a nice UHF oscillator
Well T6 enables me to skip the coupling capacitor Pedja.
Could be. I'm not into the non-oversampling hypeBricolo said:Maybe the question Peter wanted to ask (and mee too
does it need an additional filter when used with a non oversampling dac?
If yes, what filter would fil?
You might wanna read at the begin of this thread
BTW, I started with the version for the TDA1543, should be able to post next weekend.
rbroer said:
Yep, I mean what I wrote, there was a CFP (1k feedback resistor) for each individual transistor in the schematic.
Turned out I made a nice UHF oscillator
Well T6 enables me to skip the coupling capacitor Pedja.
Could be. I'm not into the non-oversampling hype
You might wanna read at the begin of this thread
BTW, I started with the version for the TDA1543, should be able to post next weekend.
Nice design.
Myself and C. Buckingham have implemented heaps of these
I-V's. BJT, Jfet, MOS, folded and non-folded, SE complementary etc
etc.
Getting the the CFP's to not oscillate is no problem,
must have base stoppers on some or all BJTs, also
uninterupted gnd plane and good bypasses help.
Getting CFP to sound as good as non CFP *IS* a problem.
It always had an amazingly clean presentation (it will have
lower THD) but just seemed to lack the utter naturalness of
non CFP iterations. In our experience, CFP is sterile, non-CFP
sings.
WRT BC557/547 Vs 2sa970/sc2240 (BL) , you can get VG
results with 557C/547C but having checked the data sheets
of 970/2240 they DO look even better WRT Hfe linearity vs
current over a wide range, also have very low noise.
Gotta try some a those.... should have known Jocko
Cheers,
Terry
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