Hi Diomedian,
Yes i am using an 18vdc wallwart. I basically just ran a wire from the negative rail to the chassis. The increase in sound quality improved by a big margin articulation became much clearer, as did instruments and there positions, also bass lines are much easier to follow. So would definetely recommend grounding the chassis. Well thats my experience with it anyway. Also lowering the 1k resistors to 330ohm help further clear things up and bass seems much tighter.
Alon
Yes i am using an 18vdc wallwart. I basically just ran a wire from the negative rail to the chassis. The increase in sound quality improved by a big margin articulation became much clearer, as did instruments and there positions, also bass lines are much easier to follow. So would definetely recommend grounding the chassis. Well thats my experience with it anyway. Also lowering the 1k resistors to 330ohm help further clear things up and bass seems much tighter.
Alon
Malka07 said:
It took me quite a while, but I finally found Papa's recommendation - back on page 31, our friend ABO shorted the output resistor and reduced the input to 100R. Papa noted that he didn't recommend shorting the output but would "recommend exploring lower values, such as 221 ohms."
Thanks for the pointer, Malka07!
-j
Nelson,
While you are on the topic, what is the best method to ground the chassis?
Thanks,
Keith Lockwood
Sam with the showing scalp flat top, particular about the point it made.
F.Z.
From "Bongo Fury", performed live in concert at the Armadillo Word Headqaurters, Austin ,Texas May 20th&21st, 1975
While you are on the topic, what is the best method to ground the chassis?
Thanks,
Keith Lockwood
Sam with the showing scalp flat top, particular about the point it made.
F.Z.
From "Bongo Fury", performed live in concert at the Armadillo Word Headqaurters, Austin ,Texas May 20th&21st, 1975
B1 DC on output
Hi,
I just built the B1 using Pass pcb.
When I turn on the B1, I see 2VDC on the output, this is
after the 10uF coupling cap
After few seconds, it will
drop down to 0V. Is this normal? In this case, I would
get big turn on thump?
I'm using LM1084 VR set and output measures 18.5VDC for
psu.
I'm using 1000uF 100V x2 since that's what I have on hand
for filter caps.
Is JFET JBOZ (single fet from NP) sound quality same as B1?
If I build JBOZ, it's pretty much the same SQ but with more gain?
thanks!
Hi,
I just built the B1 using Pass pcb.
When I turn on the B1, I see 2VDC on the output, this is
after the 10uF coupling cap
After few seconds, it willdrop down to 0V. Is this normal? In this case, I would
get big turn on thump?
I'm using LM1084 VR set and output measures 18.5VDC for
psu.
I'm using 1000uF 100V x2 since that's what I have on hand
for filter caps.
Is JFET JBOZ (single fet from NP) sound quality same as B1?
If I build JBOZ, it's pretty much the same SQ but with more gain?
thanks!
ah, you answered my question with your question
I had no load on it at all since I wanted to check out everything
first. Good thing I did, if not, it would have been quite a disaster.
I connected 2nd pot wrong, had CCW tied to CW on pot.
NP pcb is on opposite side for ccw, I did not notice this, duh. When I measured AC with DMM, I noticed it was full voltage.
rewired. it's up and running now. thanks again.
Dobs said:Stoopid question, but what is the difference between a preamp and a buffer?
Look the exact same thing to me
GAIN!
A preamp has gain (o/p signal higher than i/p), a buffer doesn't (o/p = i/p).
What's the purpose of a buffer then? To lower the impedance and to "isolate" source and the next component in the chain.
B1 offers also a volume control.
A buffer typically has a gain of 1, i.e. no gain. Its job is to offer input and output impedance that play nicely with sources and amplifiers. And likely some volume control in there as well as a source selection capability.
A preamp will have some gain. The amount of gain depends on the design. It too, will have its own input and output impedance more or less suited to different sources and amplifiers and a volume control. In more complex pre-amps, you have a the ability to select different sources as well. Sometimes known as a 'control amp'.
That's my understanding (albeit limited) of things. Some have said I know, or don't know, "diddly squat"; so take my response for what it is worth
Ryan
ps... yeah, what he said
A preamp will have some gain. The amount of gain depends on the design. It too, will have its own input and output impedance more or less suited to different sources and amplifiers and a volume control. In more complex pre-amps, you have a the ability to select different sources as well. Sometimes known as a 'control amp'.
That's my understanding (albeit limited) of things. Some have said I know, or don't know, "diddly squat"; so take my response for what it is worth
Ryan
ps... yeah, what he said
massimo said:
GAIN!
A preamp has gain (o/p signal higher than i/p), a buffer doesn't (o/p = i/p).
What's the purpose of a buffer then? To lower the impedance and to "isolate" source and the next component in the chain.
B1 offers also a volume control.
Ok,
So the B1 to stay a buffer the volume control need to be passive, otherwise it will add some gain and become a preamp right?
B1 chassis grounding
NP has said that chassis grounding is important, but which way is correct? The mounting holes on the PCB have exposed ground traces around them, so if you use metal screws and metal chassis, a ground will be established at each corner of the PCB. I was always under the impression that there should be only one path to ground. I am in the process of building the B1 and was planning to use an IEC jack and tie its ground pin to the chassis - the PCB board would be isolated using nylon screws, and RCAs would be insulated from chasis as well. In fact, the IEC ground to chassis connection would be the only contact with chassis, so effectively, the circuit would float. Is this incorrect? Am I heading in the direction of hum city?
NP has said that chassis grounding is important, but which way is correct? The mounting holes on the PCB have exposed ground traces around them, so if you use metal screws and metal chassis, a ground will be established at each corner of the PCB. I was always under the impression that there should be only one path to ground. I am in the process of building the B1 and was planning to use an IEC jack and tie its ground pin to the chassis - the PCB board would be isolated using nylon screws, and RCAs would be insulated from chasis as well. In fact, the IEC ground to chassis connection would be the only contact with chassis, so effectively, the circuit would float. Is this incorrect? Am I heading in the direction of hum city?
Thanks a lot Nelson.
I was wondering the very same thing.
I guess being a newbie to DIY am a bit of a worry wart(I guess better than being a wall wart) and I like to hear things like this right from the man himself.
Thanks again.
Keith
Is that a real poncho? Or a Sears poncho, Hmm, no foolin'.
F.Z.
I was wondering the very same thing.
I guess being a newbie to DIY am a bit of a worry wart(I guess better than being a wall wart) and I like to hear things like this right from the man himself.
Thanks again.
Keith
Is that a real poncho? Or a Sears poncho, Hmm, no foolin'.
F.Z.