OK, it would be a waist of energy but you can put a voltage divider behind the Borboli,
say 1/3, for example a 200 Ohm and a 100 Ohm resistor. The Boboli will then see 300 Ohm loading and the Paradise will see 100 Ohm. Even when you make the input impedance of the Paradise 150 Ohm ( the same then the Boboli has ) it will reduce it´s output by 6dB already.
say 1/3, for example a 200 Ohm and a 100 Ohm resistor. The Boboli will then see 300 Ohm loading and the Paradise will see 100 Ohm. Even when you make the input impedance of the Paradise 150 Ohm ( the same then the Boboli has ) it will reduce it´s output by 6dB already.
Ok back to same work.
Little one gone back
Yes seems he does have audio virus 2, He was able to load and set up telly for his DVD since 2 & 1/2 and he likes records more than CD, his favourites are James Brown and Talking Heads we have best time taking F5 to silly levels and bouncing around Living Room.
He be 4 in August and we have been shopping around for school uniforms.
Boards are powered up I need to sort out supply and pre-regulator + how to fit the lot in the box I have at present but it looks like I will have to go shopping for new one as I like to keep traffo away from rest.
I will of course get last few resistors before I really start listening
Saying that a couple of quick square taken at 10Khz and 1Khz
This is al open on the bench trough an anti-RIAA no screening whatsoever and fluorescent tube just few inches away.
Impressive?
I am really!!!
Hopefully I may be able to listen to in next couple of days (got to finish pre amplifier as well)
After that I be on Holidays to Venice and getting Yearly fix of live concerts.
Little one gone back
Yes seems he does have audio virus 2, He was able to load and set up telly for his DVD since 2 & 1/2 and he likes records more than CD, his favourites are James Brown and Talking Heads we have best time taking F5 to silly levels and bouncing around Living Room.
He be 4 in August and we have been shopping around for school uniforms.
Boards are powered up I need to sort out supply and pre-regulator + how to fit the lot in the box I have at present but it looks like I will have to go shopping for new one as I like to keep traffo away from rest.
I will of course get last few resistors before I really start listening
Saying that a couple of quick square taken at 10Khz and 1Khz
This is al open on the bench trough an anti-RIAA no screening whatsoever and fluorescent tube just few inches away.
Impressive?
I am really!!!
Hopefully I may be able to listen to in next couple of days (got to finish pre amplifier as well)
After that I be on Holidays to Venice and getting Yearly fix of live concerts.
Attachments
Ricardo, there is a way to cancel the input offset, even with higher value load resistors or higher impedance cartridges. I have shown that before and will adopt it for the Paradise.
It is a local feedback loop around the input stage. It theoretically also reduces distortion.
I will draw the circuit tomorrow.
It is a local feedback loop around the input stage. It theoretically also reduces distortion.
I will draw the circuit tomorrow.
Here is an interesting phono stage. The 82 Ohm resistor in the source of the input Fet makes me doubt if this is the optimum solution for very low noise with low impedance MC cartridges but the "mono ruble filter" is an idea that has to be tested.Phono Pre-amp Circuit
That is what I was looking for, I remenber you posted that solution before but can not find the post.
I will wait for yout drawing.
Regards
Ricardo
Here is the offset cancelation circuit. Values of the emitter resistors are for the Paradise R2.
The original ones where a bit lower but that does not matter. Tapping into one pair of input transistors is enough. Connect the loading resistor, 2kOhm in this case, without connecting the cartridge. Set the DC at the input to 0V with the trimmer. Connect the cartridge and look if there is any fine trim necesarry.
It may be that the 10kOhm resistor has to be lowered somewhat, say to 6,8kOhm. If that does not help the trimmer can be lowered too, say to 50kOhm.
There are other options to trim the input offset, also automatic with a current mirror and servo that injects current into the input but i prefer this passive solution because it does not inject noise.
The original ones where a bit lower but that does not matter. Tapping into one pair of input transistors is enough. Connect the loading resistor, 2kOhm in this case, without connecting the cartridge. Set the DC at the input to 0V with the trimmer. Connect the cartridge and look if there is any fine trim necesarry.
It may be that the 10kOhm resistor has to be lowered somewhat, say to 6,8kOhm. If that does not help the trimmer can be lowered too, say to 50kOhm.
There are other options to trim the input offset, also automatic with a current mirror and servo that injects current into the input but i prefer this passive solution because it does not inject noise.
Well, finally I got to connect the paradise in my system and there are news...
No worries about input offset.... with a Denon DL160 and 1kr loading there is no input offset.
It seems my choice of riaa values are ok because I have a nice midrange without any harshness (subjectively speaking).
Bass is strong, punchy and detailed. Highs are clear with loads of micro detail... good.
I can not go deeper in my listening impressions because only one channel is amplifying... the other one is silent. So I had to listen with two riaas connected, using the right channel of my resident jfet SE thing to evaluate.
I am having trouble with the shunt in my "bad" channel. On negative shunt I measure around 43V on TP201 TP202 (the good one measures around 29v)
Output of the shunt is ok at -24v... do not know the implications, but the truth is it does not work.
I have a steady 7mV output offset and no sound.
No worries about input offset.... with a Denon DL160 and 1kr loading there is no input offset.
It seems my choice of riaa values are ok because I have a nice midrange without any harshness (subjectively speaking).
Bass is strong, punchy and detailed. Highs are clear with loads of micro detail... good.
I can not go deeper in my listening impressions because only one channel is amplifying... the other one is silent. So I had to listen with two riaas connected, using the right channel of my resident jfet SE thing to evaluate.
I am having trouble with the shunt in my "bad" channel. On negative shunt I measure around 43V on TP201 TP202 (the good one measures around 29v)
Output of the shunt is ok at -24v... do not know the implications, but the truth is it does not work.
I have a steady 7mV output offset and no sound.
What is the voltage between TP201 and 202? This is Paradise V1? What is the input voltage?