Hopefully, just a final question.
All the LT is now fine and I'm checking HT.
I'm checking voltages against values given in Alan's earlier post.
This is what they should be.
V1 pin 1 and 6, 82-95V, depends on MM/MC mode, Jfet characteristics and LED forward voltage. More importantly the 33K anode load resistor should have 105-110V at the high voltage end.
This is from the MosFet and derived from a voltage divider from full HV supply.
V1 pin 3 and 8, around 2V (1.8-2.2) again depends on Jfet characteristics and LED forward voltage in MM mode.
V2 pin 1 and 6, around 130V, depends on the ECC83.
V2 pin 3 and 8, around 0.9V
V3 pin 1 and 3, this is full HT, 225-235V perfect.
V3 pins 3 and 8, around 135V, depends on ECC83. Make sure the 1N4001 is in the right way around
This is what I'm measuring
V1 - 1 & 6 - 87.9 & 88, 3 & 8 - 1.99 & 2
Voltage on anode load resistor (which I'm taking to be R11P) around 200 at one end, 111 at the other.
V2 - 1 - 118.5, 6 - 122.9, 3 - .865, 8 - .823
V3 - 1 & 6 - both 214, 3 - 119.7, 8 - 124.5
So V1 looks spot on, V2 somewhat low (valve is an old used Mullard), and V3 seems low.
One other thing is that Alan states there should be around 10v voltage drop across R9P, I have no drop at all over that resistor.
Are these values acceptable, or is there a problem?
Many thanks.
All the LT is now fine and I'm checking HT.
I'm checking voltages against values given in Alan's earlier post.
This is what they should be.
V1 pin 1 and 6, 82-95V, depends on MM/MC mode, Jfet characteristics and LED forward voltage. More importantly the 33K anode load resistor should have 105-110V at the high voltage end.
This is from the MosFet and derived from a voltage divider from full HV supply.
V1 pin 3 and 8, around 2V (1.8-2.2) again depends on Jfet characteristics and LED forward voltage in MM mode.
V2 pin 1 and 6, around 130V, depends on the ECC83.
V2 pin 3 and 8, around 0.9V
V3 pin 1 and 3, this is full HT, 225-235V perfect.
V3 pins 3 and 8, around 135V, depends on ECC83. Make sure the 1N4001 is in the right way around
This is what I'm measuring
V1 - 1 & 6 - 87.9 & 88, 3 & 8 - 1.99 & 2
Voltage on anode load resistor (which I'm taking to be R11P) around 200 at one end, 111 at the other.
V2 - 1 - 118.5, 6 - 122.9, 3 - .865, 8 - .823
V3 - 1 & 6 - both 214, 3 - 119.7, 8 - 124.5
So V1 looks spot on, V2 somewhat low (valve is an old used Mullard), and V3 seems low.
One other thing is that Alan states there should be around 10v voltage drop across R9P, I have no drop at all over that resistor.
Are these values acceptable, or is there a problem?
Many thanks.
They are all good. V2 voltages are dependent on the valve.
HT seems a little low but will work fine.
As a final check what AC do you have from the transformer?
HT seems a little low but will work fine.
As a final check what AC do you have from the transformer?
Thanks Alan
AC from transformer is
HT, 178v with valves in, 183.3v with valves out.
LT, 10.2v with valves in, 10.8v with valves out.
I've had it running and it sounds great.
Many thanks for a brilliant design, and answering my daft questions.
AC from transformer is
HT, 178v with valves in, 183.3v with valves out.
LT, 10.2v with valves in, 10.8v with valves out.
I've had it running and it sounds great.
Many thanks for a brilliant design, and answering my daft questions.
This phono stage has excellent sound, but if I have one complaint it would be bass area. It sounds thinner, not much, but it lacks some energy and punch.
I've decided to buy Focusrite soundcard and measure this phono stage with it, with antiriaa circuit.
My ears did not fool me and the original frequency responce shows about ~1.5dB lower output below 1kHz and about additional 0.5dB below 100Hz. I've tried ECC803S JJ and Telefunken ECC83. I forgot to measure it with 6N2P-EV.
So, with one little mod this can be easily corrected. R17L and R17R are 33K. Solder 180K acros them or replace 33K with 28K.
It sounds better now. A great phono stage indeed.
Pictures are scaled as they are, they are directly exported from REW.
Regards
I've decided to buy Focusrite soundcard and measure this phono stage with it, with antiriaa circuit.
My ears did not fool me and the original frequency responce shows about ~1.5dB lower output below 1kHz and about additional 0.5dB below 100Hz. I've tried ECC803S JJ and Telefunken ECC83. I forgot to measure it with 6N2P-EV.
So, with one little mod this can be easily corrected. R17L and R17R are 33K. Solder 180K acros them or replace 33K with 28K.
It sounds better now. A great phono stage indeed.
Pictures are scaled as they are, they are directly exported from REW.
Regards
Attachments
New BOM
BB3 - New BOM - Google Sheets
Please note, i am still in the process of checking the Part Numbers against current stock options.
BB3 - New BOM - Google Sheets
Please note, i am still in the process of checking the Part Numbers against current stock options.
Just a quick question,
Is their any reason not to use a case mounted switch running from the jumper pins to change from 6n2p to ecc83?
Is their any reason not to use a case mounted switch running from the jumper pins to change from 6n2p to ecc83?
[emoji106]
The BB3 hasn't been available to DIY for some time now.
Good luck with your project [emoji4]
I am so glad I bought a board when they were available. Currently listening in MM mode with my Decca Gold and loving it.
Fantastic.
It's still nice to hear the positivity for the Phonostage.
Never tried a Decca Gold with a BB3......should I revisit? I'll think about it.
I wonder the same,kan there be a shourtcut if the switch is set in the wrong possision?
Me to,I just sold my paradise phonostage,I think its more fun listening to the Bigbottle....