I just found out that i can live without the tefloncaps at 135Dollars a pop. I will start with the 1uf Rifa mkp i have lying around for now
I meant the Russian military NOS FT-3 and the like.... they are quite inexpensive and effective.
0 47uF 5 200V Teflon Hi End Capacitors ft 3 Lot of 1 | eBay
I have now checked the voltage on pin 6 of the opamp - its 7V for one channel and 16 for the other. This is very dissapointing since I put significant effort in matching the transistors, they are matched far better than 5%.
I would say, be not too disappointed
a tiny difference makes for a large output difference on the servo (it does not have a very large 'authority'). The ‘true’ effect of the servo can only be seen at R5. I would say, as long as the pin 6 voltage is below 2/3's of the supply voltage (+ or -) it is fine.
Hi Frans,
Yes, I'm more worried about the channel that has 16V which is too high. Strangly I can adjust my input offset to less than 1mV and it stays there on that channel, too.
Can you explain about R5, it's not mentioned in the guide.
Regards
Sven
PS: These are my input stages:
Yes, I'm more worried about the channel that has 16V which is too high. Strangly I can adjust my input offset to less than 1mV and it stays there on that channel, too.
Can you explain about R5, it's not mentioned in the guide.
Regards
Sven
PS: These are my input stages:
An externally hosted image should be here but it was not working when we last tested it.
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Hi Sven,
Oeps I did 'over'-read that (the 16V) and yes that is marginal to say the least. I should not say too much about this stuff, as the RIAA itself is not my terrain. But I can say the next; the R5 resistor is where the servo output is added/injected into the RIAA, and thus where the servo tries to control the offset. There are other people here that should look at your measurements
Regards,
Frans
In my opinion you can do a simple test if everything is working as should. Just give (temporarily) the servo a bit more authority. Do this by paralleling the 150K (R43a and R43b) with an extra set of 150K resistors (effectively halving there value to 75K). This will not harm anything, but (in my opinion again ) it should about halve the voltage at pin 6 of the opamp. And (if it halves’) thus confirm that everything is operating as should.
I would like to see some additional comments on this (from the RIAA experts here).
) it should about halve the voltage at pin 6 of the opamp. And (if it halves’) thus confirm that everything is operating as should.I would like to see some additional comments on this (from the RIAA experts here
).
Just one additional comment - I'm still waiting for my RIAA resistors to arrive and in the meanwhile (to allow caps to form) I'm using a 18k resistor in the external RIAA connector which may (?) result in the circuit behaving differently. This is also the reason why I'm only measuring stuff and not listening to it. Probably better to wait until the "real" RIAA network is installed and worry about it then.
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Found a little amount of time at the weekend to work on the paradise.
One channel is working realy fine.
-The other is worse.
First I got -15,4V at the Output and on RIAA. Checked all mirrors and the inputstage.
After changing the trannies in the input (real close matched!!) the voltage changed to +15 V.
First thought about an error at measurement. But I`m shure that I picked the right polarity.
Any Ideas to solve this?
One channel is working realy fine.
-The other is worse.
First I got -15,4V at the Output and on RIAA. Checked all mirrors and the inputstage.
After changing the trannies in the input (real close matched!!) the voltage changed to +15 V.
First thought about an error at measurement. But I`m shure that I picked the right polarity.
Any Ideas to solve this?
Found a little amount of time at the weekend to work on the paradise.
One channel is working realy fine.
-The other is worse.
First I got -15,4V at the Output and on RIAA. Checked all mirrors and the inputstage.
After changing the trannies in the input (real close matched!!) the voltage changed to +15 V.
First thought about an error at measurement. But I`m shure that I picked the right polarity.
Any Ideas to solve this?
What's your servo output voltage? And, did you put a "neumann" resistor or a wire?
Then somethign else is wrong. Can you please check the voltage on both ends of R5? Should be +/- 0.6V
Hallo Zusammen
Habe jetzt 4 Paradise Platinen gelötet, alle Werte waren OPTIMAL, nur der Offset Drift
ging von 120mv- bis 120mv +, was nur ein Temperatur problem ist.
Habe probehalber ein kleines Pappgehäuse über ALLE Kleintransistoren gebastelt, und
der Offset hat nur noch eine Drift von 5mv !!!
Jetzt bin ich zufrieden ;-))))
Lieben Gruß Heinz
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translated by moderation
Hi
Paradise now have 4 boards soldered, all values were OPTIMAL, only the offset drift
decreased from 120mV to 120mV, +, which is just a temperature problem.
Have ..(tentatively wrote(???))... a tiny Pappgehäuse about ALL small transistors, and
The offset is only a drift of 5mV!
Now I'm happy;-))))
Kind regards Heinz
Habe jetzt 4 Paradise Platinen gelötet, alle Werte waren OPTIMAL, nur der Offset Drift
ging von 120mv- bis 120mv +, was nur ein Temperatur problem ist.
Habe probehalber ein kleines Pappgehäuse über ALLE Kleintransistoren gebastelt, und
der Offset hat nur noch eine Drift von 5mv !!!
Jetzt bin ich zufrieden ;-))))
Lieben Gruß Heinz
********************************
translated by moderationHi
Paradise now have 4 boards soldered, all values were OPTIMAL, only the offset drift
decreased from 120mV to 120mV, +, which is just a temperature problem.
Have ..(tentatively wrote(???))... a tiny Pappgehäuse about ALL small transistors, and
The offset is only a drift of 5mV!
Now I'm happy;-))))
Kind regards Heinz
Hallo Zusammen
Habe jetzt 4 Paradise Platinen gelötet, alle Werte waren OPTIMAL, nur der Offset Drift
ging von 120mv- bis 120mv +, was nur ein Temperatur problem ist.
Habe probehalber ein kleines Pappgehäuse über ALLE Kleintransistoren gebastelt, und
der Offset hat nur noch eine Drift von 5mv !!!
Jetzt bin ich zufrieden ;-))))
Lieben Gruß Heinz
********************************
Hi
Paradise now have 4 boards soldered, all values were OPTIMAL, only the offset drift
decreased from 120mV to 120mV, +, which is just a temperature problem.
Have ..(tentatively wrote(???))... a tiny Pappgehäuse about ALL small transistors, and
The offset is only a drift of 5mV!
Now I'm happy;-))))
Kind regards Heinz
What is a 'Pappgehäuse'? Do not isolate the transistors, compleatly, from the environment! They will 'collect' heat, and then will over-heat (it's not a pretty sight
).What is a 'Pappgehäuse'? Do not isolate the transistors, compleatly, from the environment! They will 'collect' heat, and then will over-heat (it's not a pretty sight
He was just trying... Nevertheless, that points towards an interesting insight, that simply by isolating from air movement the drift reduces significantly. Have to try this at home....
great job heinz! let us know your listening experience...
Hi,
i have just finished populating the boards and i have no words on how thankful i am to the organizers if the pcb`s and the discrete element group by. alfred and joachin have gotten a lot of well deserved credit here, but all the work that went into sorting caps and resistors - this was birger`s part i understand - leave me with extreme gratitude.
now, while i am waiting for the transformers to set my stuff on fire i keep wondering about several things:
- the thermal drift issues in the entrance stage.
we all have seen how little temperature differences did mess up the hfe measurements, illustrating how disatrous temperature differences can be for a circuit full of high gain trannies. so how about thermocoupling pairs of transistors together?? the cardbord box heinz mentioned could be understood like this, thermocoupling by placing in the same (but totally uncontrolled - FdW) ambient temperature.
a far better way must be bridging all eight input transistors by glueing a copper bar across their tops, thus eliminating temperature differences without risk for thermal runaway? same with other functional pairs like, basically these circled in blue in the assembly guide. i did couple transistorpairs in my symasym, as it was mentioned in the documentation.
i leave other question unasked for now, as i make progress with my thermocoupling i will post pictures.
i have just finished populating the boards and i have no words on how thankful i am to the organizers if the pcb`s and the discrete element group by. alfred and joachin have gotten a lot of well deserved credit here, but all the work that went into sorting caps and resistors - this was birger`s part i understand - leave me with extreme gratitude.
now, while i am waiting for the transformers to set my stuff on fire
i keep wondering about several things: - the thermal drift issues in the entrance stage.
we all have seen how little temperature differences did mess up the hfe measurements, illustrating how disatrous temperature differences can be for a circuit full of high gain trannies. so how about thermocoupling pairs of transistors together?? the cardbord box heinz mentioned could be understood like this, thermocoupling by placing in the same (but totally uncontrolled - FdW) ambient temperature.
a far better way must be bridging all eight input transistors by glueing a copper bar across their tops, thus eliminating temperature differences without risk for thermal runaway? same with other functional pairs like, basically these circled in blue in the assembly guide. i did couple transistorpairs in my symasym, as it was mentioned in the documentation.
i leave other question unasked for now, as i make progress with my thermocoupling i will post pictures.
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