Try to search metal pen holder or cutlery holder with appropriate size.
It's a little ugly, but effective if you can ground it aesthetically.
It's a little ugly, but effective if you can ground it aesthetically.
Dear All,
Noob question. I've some Buz 901 on hand, can this be use to build a source follower ?
If so, would appreciate a guidiance on how to set it up to work optimally with 01a.
many thks
Noob question. I've some Buz 901 on hand, can this be use to build a source follower ?
If so, would appreciate a guidiance on how to set it up to work optimally with 01a.
many thks
I am starting to build 01a preamp and I can not find any information if filament pin1 is positive or negative or it does not matter? Other thing is that if I use Rod Coleman V9 regulator with 6 sic diodes connected to the positive side and sic diode cathode to the overall amp ground (not regulator - negative?)?
Like in this picture?
Like in this picture?
I built the Bartola 01a line stage a few years ago. Never got the hum controlled. Have a few ideas and will get back to it one day. Good luck with yours.
Connect the diodes to the negative side, with the V9.
I think it's worth comparing the sound of a good resistor - like the excellent non-inductive (Ayrton Perry wound ) Ohmite WNE, with a DC link bypass capacitor, against the diodes.
What value resistor and bypass capacitor to use with CX-301a? So the connection would be as shown in the picture?
It's not filament biased version, so via resistor (or diode string) only the tube cathode current (few mA) flowing.
In the #704 post the schematic is simple cathode biased version (with diode string). The R.C. regulator feeds only the filament.
If you change diode string to (relatively large) resistor, must to use (relatively large) bypass capacitor.
Sample:
If you change diode string to (relatively large) resistor, must to use (relatively large) bypass capacitor.
Sample:
SIC diodes sound edgy and unpleasant on music like classical and opera. I tore them all out and used good resistors and DC Link caps. Filament bias is even better.
I'm not surprised you preferred the resistor, Andy! I don't like diodes of any kind in the cathode.
Filament bias is perfect for 01A stages (only burns ca. 1.2W in the resistor), but you need to change the DC input voltage to 14 - 17V, to get the same 5V bias.
If you can make up 20 to 22 ohm with available Ohmite WNE resistors (parallel preferred) that will be well worth listening to.
The Ohmites are industrial resistors, made with high quality materials and construction, including copper leads, & Ayrton Perry winding .
They should be able to challenge most audio types IMHO
Filament bias is perfect for 01A stages (only burns ca. 1.2W in the resistor), but you need to change the DC input voltage to 14 - 17V, to get the same 5V bias.
If you can make up 20 to 22 ohm with available Ohmite WNE resistors (parallel preferred) that will be well worth listening to.
The Ohmites are industrial resistors, made with high quality materials and construction, including copper leads, & Ayrton Perry winding .
They should be able to challenge most audio types IMHO
If I use 20 ohm resistor then I connect it like in this schematic? What would then be a good bypass capacitor for that?
@euro21 Why are you using in the #712 post in filament 1k resistor R2 with 1000uF if others use only 20-25 ohm resistor? What is the difference? In this schematic pin 4 is used as positive voltage from regulator and pin 1 is flowing to ground through resistor and cap?
@euro21 Why are you using in the #712 post in filament 1k resistor R2 with 1000uF if others use only 20-25 ohm resistor? What is the difference? In this schematic pin 4 is used as positive voltage from regulator and pin 1 is flowing to ground through resistor and cap?
In post #704 the schematic shows cathode biasing.
In the #715 it's filament biasing.
Another animals. 😉
In the #715 it's filament biasing.
Another animals. 😉
Yes, for filament bias, connect it like that. No need for a bypass capacitor: with filament bias, the Rk of 20 .. 22 ohm is low enough already.
BTW, low filament current is not recommended for long term use. At 200mA, the 01A might only live for ca. 100 hours. You can adjust the filament current to get 4.75V on the socket, but lower than that is not good.
Hi Rod,
The WNE range seems quite limited. To get 20R for filament bias I would have to connected two
WNE10RFET in series. Or two 50R an and one 100R in parallel. They seem reasonably priced at Digikey. Go parallel? Do you personally prefer these to the Mills MRA12?
4.75V at the socket is approx 235ma. Do I understand you correctly that it is best to keep the current at least that much?
Thanks. Nash
The WNE range seems quite limited. To get 20R for filament bias I would have to connected two
WNE10RFET in series. Or two 50R an and one 100R in parallel. They seem reasonably priced at Digikey. Go parallel? Do you personally prefer these to the Mills MRA12?
4.75V at the socket is approx 235ma. Do I understand you correctly that it is best to keep the current at least that much?
Thanks. Nash
Two 10R in series looks fine; there's a tiny noise improvement with parallel, but that applies to cheaply constructed parts more (current noise in the end cap and leadout attachment points).
I am not suggesting to throw out MRAs to fit the ohmites, but they are worth comparing, on account of excellent materials and low parasitics at a attractive price.
The specification for filament heating temperature is calibrated against the voltage, so the -5% must be applied to the 5V. Current between samples is not controlled nor specified, beyond the guide value.
I am not suggesting to throw out MRAs to fit the ohmites, but they are worth comparing, on account of excellent materials and low parasitics at a attractive price.
The specification for filament heating temperature is calibrated against the voltage, so the -5% must be applied to the 5V. Current between samples is not controlled nor specified, beyond the guide value.
Thanks Rod.
Always appreciate your suggestions. For $7 most certainly worth the try.
I had not realized the link between the filament voltage at the socket to the filament heating temperature. I was fixated on the 0.25 amp current guide value. Just reset the Vfil to 4.75V. Measurement acoss the 19.5R resistor is 4.90V ie 0.251amps. What is the -5%? Is it an established safe de rating number for this tube?
Always appreciate your suggestions. For $7 most certainly worth the try.
I had not realized the link between the filament voltage at the socket to the filament heating temperature. I was fixated on the 0.25 amp current guide value. Just reset the Vfil to 4.75V. Measurement acoss the 19.5R resistor is 4.90V ie 0.251amps. What is the -5%? Is it an established safe de rating number for this tube?