Tried a little more measurings to find my fault(s).
I can verify most of Heseners values, he published in the schematic amplifier annotated.pdf http://www.diyaudio.com/forums/group-buys/216891-paradise-phono-stage.html but I have ca. 5 V at pin 6 of the opa134 (should be around 0,5 V), on both of my boards.
Don't know how to fix this.
Christoph
Last edited:
Looking good.
Let the boards on for some days... the output offset will come down as the capacitors settle.
In my case, I was able to listen to good sounds once the offset became lower than 15mV
After some time, the offset is now 4mV
Do you have the scope (at least 50MHz) to check the stability? In my phono pre, I cannot use AD797 for example, if I do, I have similar problems you describe here (measured with DMM), with scope I would measure 13.5MHz oscillations of some 40mV - with AD797 in my phono preamp.
Which of these in Germany is similar to those in UK?
Bipolar-Standard-Leistungstransistor Diotec BC 327-40 PNP Gehäuseart TO 92 I(C) -800 mA Emitter-Sperrspannung U(CEO) -45 im Conrad Online Shop | 155829
Transistor bipolar Diotec BC 327-40 BK PNP Gehäuseart TO 92 I(C) -1 A Emitter-Sperrspannung U(CEO) -50 V im Conrad Online Shop | 140535
They are both from diotec, one with UCEO -50V 7 I=1A
and one with UCEO -45V and 800mA?
I did nit find clearer specifications for the 327 / 337 to help to choose.
These are the ones I bought.
Diotec BC327/40 Transistor PNP TO 92 1AA -45VV from Conrad Electronic UK
Diotec BC327/40 Transistor PNP TO 92 1AA -45VV from Conrad Electronic UK
Thanks, Marra,
I know. Because I wanted to user Conrad in germany I was loooking at the german page. They only offer the mentioned type but it is different to the one you ordered.
So to avoid sending from UK (which takes longer) i can choose between:
They are both from diotec,
one with UCEO -50V / I=1A
and one with UCEO -45V and 800mA
There are no ones from germany with -45V / 1A. What parameter is more important -45V or 1A?
I know. Because I wanted to user Conrad in germany I was loooking at the german page. They only offer the mentioned type but it is different to the one you ordered.
So to avoid sending from UK (which takes longer) i can choose between:
They are both from diotec,
one with UCEO -50V / I=1A
and one with UCEO -45V and 800mA
There are no ones from germany with -45V / 1A. What parameter is more important -45V or 1A?
Of that I am unsure.The ones I bought were what appeared when I entered the transistor type into Conrads search bar.I know it says Conrad UK but mine were delivered by UPS from Germany.
This is even more crazy. UK sells for 5 pence (equal to 6 cent) but does not deliver outside UK. conrad.com sells the same spec for 18 cent, that is three times the price in UK!!! For the difference one could order in UK and send it to Germany and still save money ...
Just ordered 200 of each type from Conrad-UK. Quantity discount on 327/40 = £0.03 each nett, NO QUANTITY discount on the 337/40(!!!!!) so they cost the full £0.09 each!!!😡
Seems strange. I will phone them in a couple of days and report back.
The cheapest source for the Diotec BC327-40 and BC337-40 I found, is SOSElectronic in Slovakia:
BC327-40TAPE DIOTEC | SOS electronic
€0.0168 per transistor plus VAT (minimum order 100)
BC337-40TAPE DIOTEC | SOS electronic
€0.0166 per transistor plus VAT (minimum order 100)
Further discounts apply.
Possible drawbacks are:
- minimum order €50
- apparently doesn't deliver to private persons, only to companies.
BC327-40TAPE DIOTEC | SOS electronic
€0.0168 per transistor plus VAT (minimum order 100)
BC337-40TAPE DIOTEC | SOS electronic
€0.0166 per transistor plus VAT (minimum order 100)
Further discounts apply.
Possible drawbacks are:
- minimum order €50
- apparently doesn't deliver to private persons, only to companies.