I am with hesener in thinking that one BC327/337 is populated with the wrong polarity device. I would triple check all transistors on the pcb carefully.
Actually, at this point it would be wise to sit down with the "bad" board and triple check everything...all resistors, cap polarities, etc. It is time consuming but worth the effort.
Hi Ricardo, can you check Q49/Q50/Q51/Q52 for correct type and polarity? Something is "Clamping" the voltage at R5 and the servo cannot move the needle. Also, can there be a short to the GND plane around these transistors and R5?
Just took another look at your new measurements, and I have a suspicion around Q49 and Q50. Can you please check these two (or even replace them), and see if there is no shortcircuit to ground on the base of Q50, R5 or R46?
I think we are all curious how it sounds. I am nearly ready with my boards. I am waiting for the big Dale resistors for the RIAA.
First, I changed the input network (loading resistor and connectors) for my FPS to the same as in my Paradise, now both have Dale resistors and rotary switch with silver connectors. It did make a change towards more details and better resolution, although it was not huge.
Then I spent a few hours playing with both FPS and Paradise, both with headphones and loudspeakers, and one of my favourite records (Dead can dance live 2005). I still find that the FPS is slightly more "gentle" and "elegant", whereas the Paradise is a touch brighter and more forward. Both have the same details in my opinion, its just a very slightly different presentation.
I like the bass better in the paradise, it seems a little more defined. One thing that struck me when listening with loudspeakers was that the location of instruments and singers, the space, is breathtaking with the Paradise - I did spend a lot of time though to make sure the caps and resistors in the RIAA networks match to each other as precise as possible (if I remember correctly, I could get to better than 0.1%). Maybe I should take a look at these components in the FPS.....
Did you get the parts I sent?
Then I spent a few hours playing with both FPS and Paradise, both with headphones and loudspeakers, and one of my favourite records (Dead can dance live 2005). I still find that the FPS is slightly more "gentle" and "elegant", whereas the Paradise is a touch brighter and more forward. Both have the same details in my opinion, its just a very slightly different presentation.
I like the bass better in the paradise, it seems a little more defined. One thing that struck me when listening with loudspeakers was that the location of instruments and singers, the space, is breathtaking with the Paradise - I did spend a lot of time though to make sure the caps and resistors in the RIAA networks match to each other as precise as possible (if I remember correctly, I could get to better than 0.1%). Maybe I should take a look at these components in the FPS.....
Did you get the parts I sent?
Hi hesener
As you know I am eager to get a crack at it so keep the first set of boards from the next batch for me.
Could you compare Phase response between Paradise and FPS stage location answer lays there I think.
As you know I am eager to get a crack at it so keep the first set of boards from the next batch for me.
Could you compare Phase response between Paradise and FPS stage location answer lays there I think.
I think what you hear is also what i have experienced. Fet´s have a slightly mellower tone, call it warm, call it elegant, it is hard to describe. When you are used to tubes it is maybe easier to listen to Fet´s.
Bipolars are more crispy and tighter in the bass. One explanation i have is the lower 1/F corner and they have more Gm.
Have you checked the RIAA precision again with another method ?
Maybe there is a slight difference that explains some tonal differences.
Some sources say that 0,2dB in octave to octave balance is just audible.
Yes, maybe your Paradise has better channel match then your FPS. The FPS i have, made by Pilgham Audio is plus-minus 0,1dB accurate so maybe it is another reason.
Anyway, i am very happy that the Paradise images well. It is important for me.
Bipolars are more crispy and tighter in the bass. One explanation i have is the lower 1/F corner and they have more Gm.
Have you checked the RIAA precision again with another method ?
Maybe there is a slight difference that explains some tonal differences.
Some sources say that 0,2dB in octave to octave balance is just audible.
Yes, maybe your Paradise has better channel match then your FPS. The FPS i have, made by Pilgham Audio is plus-minus 0,1dB accurate so maybe it is another reason.
Anyway, i am very happy that the Paradise images well. It is important for me.
FPS and Paradise should match in phase up to 200kHz. I use shunt feedback in the FPS.
That gives accurate phase in the extreme treble and does not suffer from the extra pole that parallel feedback has.
That gives accurate phase in the extreme treble and does not suffer from the extra pole that parallel feedback has.
I think you also experience that you use much better parts choices then the rather ordinary parts that come with the FPS. Still i think for what it is it is a bargain.
The parts you took for your build are also my favorites, and i listened to many over the years. One part does not make a big difference but it adds up in total.
The parts you took for your build are also my favorites, and i listened to many over the years. One part does not make a big difference but it adds up in total.
Here is my next take at inverse-RIAA, based on a schematic that Joachim was kind enough to send me. The components are ALL measured using an Agilent LCR meter that has just recently been calibrated, and they match to better than 0.1% (1kHz, 500mV). Still need to put this into an enclosure and try it out....
Forgot to mention, this has two symmetric inverse RIAA channels so 4 in total.....
Forgot to mention, this has two symmetric inverse RIAA channels so 4 in total.....
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I agree. The FPS has done so much for my system, and my ability to hear more, it is fantastic. And I could not spend 10,000,- on a phono stage "off the shelf".... you all know why ;-)
Maybe I should really try and replace a few components in the FPS to see if something can be improved. First thing would be the power supply. In fact, now that the layout is done it would be quite easy to make the "Frans" regulator a standalone PCB - maybe there would be more people interested than just myself?
Hi bksabath, of course!
great idea, lets see if I can get that measured this week....
Good that you build the Anti RIAA.
What you could try is substitute the NE5534 with OPA1641. The gain-bandwidth is the same so it should not screw up the lead-lag compensation.
Have you seen my post of a low noise modification of the input cascodes ?
What you could try is substitute the NE5534 with OPA1641. The gain-bandwidth is the same so it should not screw up the lead-lag compensation.
Have you seen my post of a low noise modification of the input cascodes ?