B1 Power Supply
Hi,
I happen to have a 24V regulated power supply (from an old Self "Advanced Pre-amp"). I am hoping to use this in the B1 buffer project, but I note that the voltage, at 24V, is right at the limit of the recommended range. Does anyone have experience or recommendations about the use of this voltage with the B1?
Thanks for the help
George
Hi,
I happen to have a 24V regulated power supply (from an old Self "Advanced Pre-amp"). I am hoping to use this in the B1 buffer project, but I note that the voltage, at 24V, is right at the limit of the recommended range. Does anyone have experience or recommendations about the use of this voltage with the B1?
Thanks for the help
George
I seem to remember Papa saying earlier in the thread that he had used it with up to 40V. Maybe he can comment...
As a side note, I replaced all of the 1uF caps with Vitamin Q's and the 15kuF Panasonic caps with 10kuF Nichicon KG's. Initial indications are: richer sound, more detail, a more fleshed out midrange, bigger bottom, and "tubier" according to friends. I also experimented with a few more supply voltages and 18V seems to be the "sweet spot", at least to my ears.
My own question that continues to go unanswered...
Can a TVC or AVC be used with this buffer?
As a side note, I replaced all of the 1uF caps with Vitamin Q's and the 15kuF Panasonic caps with 10kuF Nichicon KG's. Initial indications are: richer sound, more detail, a more fleshed out midrange, bigger bottom, and "tubier" according to friends. I also experimented with a few more supply voltages and 18V seems to be the "sweet spot", at least to my ears.
My own question that continues to go unanswered...
Can a TVC or AVC be used with this buffer?
Yep , I've built mine with a single 100k Alps blue pot and it works just fine .
My power amps are quite sensitive and I find lower value pots go from silent to too loud to soon .
the attenuator resistance should not affect the log law of the track/steps of the attenuator.
Before I built the B1 I played around with purely passive pre's and I found if I used a 25k pot the usable range before the volume got too loud was around 1 hour ( if we use the clock face method ) .
I don't know how or why but when I used 100k I get around 4 hours of usable volume control which means I can get the volume just right especially for late night listening .
So now I just stick to 100k pots , for me in my system it just works .
Hi,
I wonder if the input impedance of the receiver affected the law of the pot? A low value Rin (say 20k) and a high value (100k) linear taper pot would mimic a log law pot over part of it's rotation.
Could that explain what you heard?
Certainly this law faking resistor effect will be more pronounced with a higher pot value.
Or could your pots have had different linear taper, log law taper or audio taper to the tracks?
That too could explain the apparent difference.
Certainly it is not 100k vs 25k for what you have tried and found lacking.
If you use a 25k pot then the minimum Rin should be >=50k,
a 100k pot should feed an Rin>=200k.
I would go further and suggest a 10k log law pot with Rin~=50k
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Your 2SK389 JFET's are quite valuable at this time. You might consider selling them, if you do not need them for a project.
I have seen prices of more than $10 for 2SK389's. Here is an example:
Buy LSK170 and 2SK389 JFETS in small quantities
Just use 2SK170's for the B-1 buffer.
I have seen prices of more than $10 for 2SK389's. Here is an example:
Buy LSK170 and 2SK389 JFETS in small quantities
Just use 2SK170's for the B-1 buffer.
I have both versions of the B-1 buffer in use and I prefer the Direct Coupled B-1 [no caps]. You could sign up on Tea-Bag's pcb waitlist, if you are interested.