Ideal voltage
There has been some talk about the ideal voltage to power the B1. The specs call for 18-24v but somewhere there is a quote of Nelson saying that 10v is "magic" or "special." My thought is that at 10v there is enough voltage for dynamics but the voltage is low enough to add some second order harmonic distortion -- sort of mimicking a tubey sound.
So what are people using as their supply voltage?
There has been some talk about the ideal voltage to power the B1. The specs call for 18-24v but somewhere there is a quote of Nelson saying that 10v is "magic" or "special." My thought is that at 10v there is enough voltage for dynamics but the voltage is low enough to add some second order harmonic distortion -- sort of mimicking a tubey sound.
So what are people using as their supply voltage?
Re: Ideal voltage
This is what I remember.
Anyway, read the whole thread: I know it's huge, but worthy.
If I'm not wrong, Nelson didn't suggest a different voltage. Other guys (Zen mod ?) proposed a modified version of the circuit using a dual p.s. (+/-) gettin rid of the i/p caps. Later Salas talked about his experiments with higher voltage and found +/-10V as the magic spot for the K170s in use (I mean K170s with a specific Idss). He also eliminated the o/p caps.marc brown said:There has been some talk about the ideal voltage to power the B1. The specs call for 18-24v but somewhere there is a quote of Nelson saying that 10v is "magic" or "special." My thought is that at 10v there is enough voltage for dynamics but the voltage is low enough to add some second order harmonic distortion -- sort of mimicking a tubey sound.
So what are people using as their supply voltage?
This is what I remember.
Anyway, read the whole thread: I know it's huge, but worthy.
marc brown said:
Capacitors are a rather contentious issue around here - some claim they do more to colour the sound than any other component. The ridiculous number of "audiophile" film capacitors for sale and the almost magical properties ascribed to them would seem to back this sentiment. Regardless of what you think about capacitors in particular, reducing the parts count in the signal path is a good thing as _anything in the circuit (including things like layout) can potentially effect the signal. Don't forget we're all a bunch of nuts!
-j
marc,
I don't have the experience with caps used to carry signal.
As Diomedian posted, I chose the capacitor-less version to reduce part count and layout where the audio signal is concerned.
However, I do plan to build a budget version with 1 input rather than 2 as designed by Nelson and with budget caps. But that won't be anywhere in the near future.
Whichever route you go, just remember to enjoy the fruits of your labor!
I don't have the experience with caps used to carry signal.
As Diomedian posted, I chose the capacitor-less version to reduce part count and layout where the audio signal is concerned.
However, I do plan to build a budget version with 1 input rather than 2 as designed by Nelson and with budget caps. But that won't be anywhere in the near future.
Whichever route you go, just remember to enjoy the fruits of your labor!
someone slap me down if I'm wrong here....
Marc, I think that Nelson's remark pertained to those using a V+/V- arrangement. 10 V+ and 10 V-. If you will notice, that there is a voltage differential of 20V between + and -.
Hence, in Nelson's design, the wall wart does not have a negative rail, only positive, and he recommends 18 to 24 V.
Stick with what he recommends for the wall wart and you will be fine.
Marc, I think that Nelson's remark pertained to those using a V+/V- arrangement. 10 V+ and 10 V-. If you will notice, that there is a voltage differential of 20V between + and -.
Hence, in Nelson's design, the wall wart does not have a negative rail, only positive, and he recommends 18 to 24 V.
Stick with what he recommends for the wall wart and you will be fine.
pinkfloyd4ever said:
I think he's using a blue Panasonic 3W Metal Oxide available from Digikey. That's his preferred power resistor type.
Check the B1 article: the first picure shows a blue big resistor close the two bigger elcaps.
Mills are expensive non-inductive resistor, in that position a slightly inductive one doesn't harm at all (and it's probably better).
sonidos said:
Hi,
Can you describe further the differences between the Aunt Corey Passive Preamp and the B1?
I have the key components for the Aunt Corey unit and am trying to decide whether I should dedicate my resources for connectors (RCAs, etc.), potentiometer, switches, knobs, and case towards that or whether I should get the parts needed for the B1 instead.
Any further observation comparing the two would be most appreciated.
Also, the picture of the B1 on the First Watt site show a view inside the chassis. The pots look like they may be the PEC molded carbon units, though it's hard to say for sure. Are they, in fact, the PECs?
I've used the dual ganged stereo version of the PEC pot in several applications, and aside from the issue with tracking variation and a slight softness in the bass, I find them to be extremely musical, nicer than the Alps blue velvet or black beauty, IMO.
Thanks!
KT
KT, you'll probably have to wait just a little bit longer for an honest answer from me. I haven't finished the B1 yet and someone commented that they had built Aunt Corey's buffered passive preamp and a B1. Between the two they preferred the B1. I haven't had the chance to compare the two but I'm getting very close.
Plus, a friend of mine was a friend of Corey's and designed the buffer and sold it commercially for a while. I've attached the image here. This unit includes a hand-built Penny & Giles pot and Audioquest solid core silver wire.
If it helps, I bought a pair of PECs for the B1 and they do look awfully like what is pictured with Nelson's first photos of the B1. I believe Peter Daniel had started a thread some time ago that praised the PEC pots and I decided to give them a shot.
Let me know if you have any other questions and I'll be happy to answer when I get the chance.
Attachments
KT said:
I haven't listened to Aunt Corey's preamp but I'd probably be inclined to build the B1.
First off, it's 15 years newer. There's a learning curve. Nearly every company makes better Hi-Fi than they did 15 years ago.
Secondly, the B1 is a Nelson Pass design. He has a knack for coming up with simple circuits that outperform most everything else out there.
I have a Wavelength Sine Preamp that's about 15 years old. It has tubes and a Penny & Giles pot in it too and Jensen transformers. I look forward to comparing it to the B1 if I ever get around to building the circuit. I think I'm gonna try to build the F5 amplifier first and compare it to my SET amps.