Much more information is needed. You need to provide details.
What size fuse?
So the fuse did not blow with the B1 disconnected?
How did you determine the current?
What is the design output voltage of the power supply? What is the measured output voltage of the power supply with the B1 disconnected?
Power supply schematic? If no, what is the regulator? Is there a bleed resistor? Post pictures of the bottom of the power supply pcb and details of the top side of the board if you do not have a schematic.
What size fuse?
So the fuse did not blow with the B1 disconnected?
How did you determine the current?
What is the design output voltage of the power supply? What is the measured output voltage of the power supply with the B1 disconnected?
Power supply schematic? If no, what is the regulator? Is there a bleed resistor? Post pictures of the bottom of the power supply pcb and details of the top side of the board if you do not have a schematic.
So you should have ~24VAC feeding the PS board prior to the diode bridge, the VDC measured on the first big cap should be ~33-34VDC and the regulator (I'm supposing for the B1 is 18-24VDC) output as measured at the output of the PS board is 18-24VDC?. This tranny + PS works correctly, yes? No blown fuse? The B1 circuit should only draw 20mA max. Disconnect all the signal inputs & outputs on the B1 (leaving just the +/- DC input) and just see if powering it up blows the fuse. Take the board out of the case and just put it on something non-conductive to do the power up test.
I looked at the board pictures and the K170s, the caps and the one diode are mounted correctly as far as I can see.
Pete
I looked at the board pictures and the K170s, the caps and the one diode are mounted correctly as far as I can see.
Pete
the values are of course different than this picture - and I am using fixed resistors.
Pictures of PSU - PCB (a spare I have)
I don't know if you are 120VAC or 220-240VAC mains where you are but I'm in the USA and the fuses in my IECs are routinely rated at 250V 3A slo-blo unless it's an amp & then I only go to 5-8A. So, you should go higher in the fuse department, yes.
IMHO you don't need that much capacitance in the PS for this preamp. I would guess that you only should need 6800-8200 uF (if that much) before the regulator and 100-220uF (low ESR) after the regulator. The B1 already has 2x 10000-15000 on the board. I used a Salas SSLV 1.3 UltraBiB shunt to drive my B1 and it had 8200uF before the shunt and 220uF after.
Ben Mah....your opinion?
Cheers, Pete
IMHO you don't need that much capacitance in the PS for this preamp. I would guess that you only should need 6800-8200 uF (if that much) before the regulator and 100-220uF (low ESR) after the regulator. The B1 already has 2x 10000-15000 on the board. I used a Salas SSLV 1.3 UltraBiB shunt to drive my B1 and it had 8200uF before the shunt and 220uF after.
Ben Mah....your opinion?
Cheers, Pete
@turion64
In Denmark we use 230V mains.
right now board is disconnected from in & output.
the power earth from IEC is disconnected (before it went to chassis, which may be illegal in Denmark).
fuses are 250 mA.
I first experimented a little with slowly turning a variac up. Fuse didn’t blow. So I thought I might give it a try at 250mA.
B1 LED is on.
it’s been running idle for some 20 minutes now.
next I will reconnect in/output and mount the board back in the chassis.
if that still doesnt blow the fuses - I think I will try with some music🎶😀
In Denmark we use 230V mains.
right now board is disconnected from in & output.
the power earth from IEC is disconnected (before it went to chassis, which may be illegal in Denmark).
fuses are 250 mA.
I first experimented a little with slowly turning a variac up. Fuse didn’t blow. So I thought I might give it a try at 250mA.
B1 LED is on.
it’s been running idle for some 20 minutes now.
next I will reconnect in/output and mount the board back in the chassis.
if that still doesnt blow the fuses - I think I will try with some music🎶😀
Update: Music in the living room 😀🎶
fuse did blow - so new suspect enters the crime scene.
I decided to connect things 1 by one - switch on the B1 and see if led lightens up.
with only CD and power amp it now plays.
the main suspect will be my cambridge DAC Magic - or the connection between the DAC and B1.
but the strange thing is that it played well for hours thru the DAC last Sunday.
Thank you for all the kind help so far.
fuse did blow - so new suspect enters the crime scene.
I decided to connect things 1 by one - switch on the B1 and see if led lightens up.
with only CD and power amp it now plays.
the main suspect will be my cambridge DAC Magic - or the connection between the DAC and B1.
but the strange thing is that it played well for hours thru the DAC last Sunday.
Thank you for all the kind help so far.
Inrush current was possibly the reason for the blown 100mA fuse. I explained that in my first post (my first post). The power transformer size determines the inrush current.
So now with the 250mA fuse, it powers up without the fuse blowing if the DAC is not connected. Is that also the case with the power line ground reconnected to the chassis and no DAC connected?
@Ben Mah
Right now the earth-leg of the IEC is not connected. Most consumer electronics in Denmark have only phase and null. And in older houses the wall-plugs only supports 2 wires. There has been some discussion in the audio-diy-community in Denmark whether or it’s against regulation to attach mains ground to the chassis.
but I think I will try it out during the week (have a board meeting tomorrow evening and the birthday of my father in law’s later in the week.
would it be an idea to try to measure difference in voltage potential between the grounds of the 2 units without really connecting them?
Right now the earth-leg of the IEC is not connected. Most consumer electronics in Denmark have only phase and null. And in older houses the wall-plugs only supports 2 wires. There has been some discussion in the audio-diy-community in Denmark whether or it’s against regulation to attach mains ground to the chassis.
but I think I will try it out during the week (have a board meeting tomorrow evening and the birthday of my father in law’s later in the week.
would it be an idea to try to measure difference in voltage potential between the grounds of the 2 units without really connecting them?
I know this question may have been already asked but this thread is huge, it's very difficult to surf it. I spotted questions about B1 and current DACs, however, my question here is about voltage dacs.
My DAC has a wonderful Cirrus CS 4398 voltage output device. The 4398 output is 2.3Vrms according to the datasheet. It has the usual cheap output stage with modest op-amps and components. I'd like to upgrade the output stage to hope for something better.
From the DAC I get into a low-gain tube line stage. Can a device like the B1 replace the cheap output stage to better manage the electrical transition between the DAC output and the preamp?
I hope somebody is willing to explain if this is feasible and/or useful.
My DAC has a wonderful Cirrus CS 4398 voltage output device. The 4398 output is 2.3Vrms according to the datasheet. It has the usual cheap output stage with modest op-amps and components. I'd like to upgrade the output stage to hope for something better.
From the DAC I get into a low-gain tube line stage. Can a device like the B1 replace the cheap output stage to better manage the electrical transition between the DAC output and the preamp?
I hope somebody is willing to explain if this is feasible and/or useful.
This sounds like almost exactly the right use for this unit. The B1 supplies no voltage gain but plenty of current, which should happily upgrade the output stage from your DAC.
If you're not using other sources, you could add a volume pot and use it direct into your amps. With 2.3V output, that should be plenty loud. I've used it with both a DAC and a phono stage, and it's plenty loud still.
If you're not using other sources, you could add a volume pot and use it direct into your amps. With 2.3V output, that should be plenty loud. I've used it with both a DAC and a phono stage, and it's plenty loud still.
@rikiheck: thanks a lot.
I won't use it as a preamp because (I mean with a volume pot and source selection) because I like the my way my preamp "colors" the sound (see PS below).
Hence, I presume I just need to replace the volume pot of the B1 with resistors to achieve an optimal output impedance, isn't it? The preamp input impedance is about 30k Ohms, so what do you suggest?
- - -
PS: I listen to both well and bad sounding records. Perhaps, except that for a minority of audiophile pressings, most of my vast music collection sounds crap unfortunately. For me audio is functional to the recording one enjoys. After so many disappointing experiences, I arrived to the conclusion to reduce the number of variables. I try to pursue transparency from source to the preamp, and from the preamp to speakers. In this way I achieve the "musicality" (read colored sound) by concentrating on just one gain stage (preamp) and speakers. Maybe I am wrong, but it works for me
I won't use it as a preamp because (I mean with a volume pot and source selection) because I like the my way my preamp "colors" the sound (see PS below).
Hence, I presume I just need to replace the volume pot of the B1 with resistors to achieve an optimal output impedance, isn't it? The preamp input impedance is about 30k Ohms, so what do you suggest?
- - -
PS: I listen to both well and bad sounding records. Perhaps, except that for a minority of audiophile pressings, most of my vast music collection sounds crap unfortunately. For me audio is functional to the recording one enjoys. After so many disappointing experiences, I arrived to the conclusion to reduce the number of variables. I try to pursue transparency from source to the preamp, and from the preamp to speakers. In this way I achieve the "musicality" (read colored sound) by concentrating on just one gain stage (preamp) and speakers. Maybe I am wrong, but it works for me
Yes, just replace the pot with resistors. The input will go to the pad marked "W" (wiper), and you can put a 50k resistor, say, between that and CCW (counter-clock wise), which is ground, to establish the input impedence. (I think the pot is specified as 50k, so that's where I got that number.)
Of course these choices are up to you, but the great thing about DIY is that it's easy to experiment. I also listen to a wide variety of music and, although I would say my system is pretty transparent, it probably is on the warmer side: The amps are Pass Aleph 1.2s, which have that 'tubey' sound for which the Alephs are well known. For a while, I also had a pair of VTL MB-185s, which use 6550 tubes, and the sound was remarkably similar.
Of course these choices are up to you, but the great thing about DIY is that it's easy to experiment. I also listen to a wide variety of music and, although I would say my system is pretty transparent, it probably is on the warmer side: The amps are Pass Aleph 1.2s, which have that 'tubey' sound for which the Alephs are well known. For a while, I also had a pair of VTL MB-185s, which use 6550 tubes, and the sound was remarkably similar.
