understood. 
on the hum issue: turns out i get an increased hum no matter which source or preamp (various phono pre amps, B1, iPad) i plug into my power amp. actually the hum increases as soon as i plug interconnects into the power amp. so i guess i have to move this issue to another thread....
on the hum issue: turns out i get an increased hum no matter which source or preamp (various phono pre amps, B1, iPad) i plug into my power amp. actually the hum increases as soon as i plug interconnects into the power amp. so i guess i have to move this issue to another thread....
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In my build I'm using these for my 10uf caps at C101/C201: Mundorf - Inner Excellence
They fit the board and the price is ok. Do I need to fix them to the board with acetoxy free silicone or something similar to reduce/prevent stress on the leads? (The question is really independent of the brand, but I included the link to give dimensions.)
They fit the board and the price is ok. Do I need to fix them to the board with acetoxy free silicone or something similar to reduce/prevent stress on the leads? (The question is really independent of the brand, but I included the link to give dimensions.)
post exact schm , not pic of parts placement
desolder psu from B1 , connect 1R resistors inline with both rails , power up , measure voltage across resistors , post here
this is OT and it took me 2 month to do it
I did as you recommended and the voltage measures 30.16 V. exactly the same measurement i get without resistors.
what does that tell me ?
the issue was that by accident i attached the power supply to my b1 with reversed polarity (that was 2 month ago). you helped me troubleshoot the b1 and it seemed not to have taken any damage.
then you gave me advice on how to check if the psu survived the reverse polarity. to do so you advised me to attach 1r resistors in line with the rails and measure voltage across them. this is what i just did and the voltage is exactly the same as without resistors. now i was wondering
1) what the purpose of the measurement with the resistors in line is?
2) if that tells me that the psu is fine?
the voltage between +/- is 30v. 15v if i measure across "+" and ground or " - " and ground. that's the way its supposed to be i guess.
sorry for the confusion
then you gave me advice on how to check if the psu survived the reverse polarity. to do so you advised me to attach 1r resistors in line with the rails and measure voltage across them. this is what i just did and the voltage is exactly the same as without resistors. now i was wondering
1) what the purpose of the measurement with the resistors in line is?
2) if that tells me that the psu is fine?
the voltage between +/- is 30v. 15v if i measure across "+" and ground or " - " and ground. that's the way its supposed to be i guess.
sorry for the confusion
in line resistors where there to measure voltage sag across them , and reflect is there any malfunction
it was supposed that you do that and write back your findings , so we can proceed further if needed , or declare it OK
this way , asking zillion years later , you're just adding confusion to already confused ZM
it was supposed that you do that and write back your findings , so we can proceed further if needed , or declare it OK
this way , asking zillion years later , you're just adding confusion to already confused ZM
If you measure +/-15V on the output of that PSU it's probably fine. However, what isn't fine is that you seem to have a dual-rail PSU supplying a single-rail amplifier. Can you draw how the two boards are connected together? From an earlier picture it looks like you have previously run the B1 on two 9V-batteries in series - did it hum then?
i'm afraid you're quite right. i did use the dual power supply for the (single rail) b1. i have to admit that i really only used it for maybe 5 seconds - with reverse polarity as mentioned before. after that i only used the two 9V batteries. and yes, there was some hum - how did you know?
unfortunately i don't remember how i connected the together. i believe +15v to '-' on the B1 and -15v to '+' on the B1. Wrong obviously.
Would it be possible to use a dual supply for a single rail amp at all?
I would like to build a B1 to connect to my Amp Camp Amplifiers, I am building two, with both the switch for bridged mode and the XLR input (for balanced input).
Would the B1 be a good preamp for that setup?
Could I build the B1 with balanced outputs (and RCA input)?
Will the power supply I added work properly with the B1?
Sorry for soooo many questions..
Cheers,
Neel
Would the B1 be a good preamp for that setup?
Could I build the B1 with balanced outputs (and RCA input)?
Will the power supply I added work properly with the B1?
Sorry for soooo many questions..
Cheers,
Neel
So many grounds
I'm building the B1 and my Pass Lab board has each of four standoff holes grounded. My experience in tube amps makes me reluctant to do more than one ground connection to the case. Anybody had ground loop problems?
The board only switches the hots of the two inputs while their grounds are all commoned. In stomp boxes the sound is better with grounds switched too. Anyone have experience on isolating and switching the signal source grounds?
Thanks
Dan
I'm building the B1 and my Pass Lab board has each of four standoff holes grounded. My experience in tube amps makes me reluctant to do more than one ground connection to the case. Anybody had ground loop problems?
The board only switches the hots of the two inputs while their grounds are all commoned. In stomp boxes the sound is better with grounds switched too. Anyone have experience on isolating and switching the signal source grounds?
Thanks
Dan
I'm posting my build, below, just to share with others on the thread...
But first I'd like to thank Jim (6L6) and Gianluca (HiFi2000). Jim answered, very patiently, LOTS of questions, and Gianluca made sure the chassis fit all of the parts properly. My build and understanding certainly would have been lesser without their assistance. Their time and contribution to the threads (in Jim's case) and customer service (in Gianluca's case) certainly make the DIY experience of many folks much better. Many thanks to you both.
I built my B1 to match the ACA amps I built concurrently. The only modification I made from the stock form was to add a power switch to the front panel.My big parts splurge were the Goldpoint attenuators, which are fantastically cool. Everything inside is from the recommended parts on the BOM with exception of the Mundorf caps I purchased at a stellar discount, and then only because I couldn't find the ones NP used.The hookup wire is Kimber, the RCAs are Cardas and the switches are NKK. These aren't the cheapest parts, but are far from the most expensive. I'm not sure the unit would sound much different if I used more or less expensive parts. In fact, I'm a little amazed at how little sound signature the B1 has. NP noted that some folks find passive pre's lifeless in sound quality, but I don't find that in this case.
The B1 and the ACAs were my first builds. I think the jump in the learning curve from the ACAs to the B1, which is very easy, had more to do with learning how to pick parts from Mouser, follow a BOM and other minor skills not needed with a project like the ACAs.
I'm very happy with my little DIY system. Now I"m off to try a few more complex projects like the Pearl 2 and the AJ. I've caught the DIY bug and really enjoying learning about how the electronics "work" and the simple pleasure of putting something together with my own hands.
Thanks again to Jim and Gianluca!
But first I'd like to thank Jim (6L6) and Gianluca (HiFi2000). Jim answered, very patiently, LOTS of questions, and Gianluca made sure the chassis fit all of the parts properly. My build and understanding certainly would have been lesser without their assistance. Their time and contribution to the threads (in Jim's case) and customer service (in Gianluca's case) certainly make the DIY experience of many folks much better. Many thanks to you both.
I built my B1 to match the ACA amps I built concurrently. The only modification I made from the stock form was to add a power switch to the front panel.My big parts splurge were the Goldpoint attenuators, which are fantastically cool. Everything inside is from the recommended parts on the BOM with exception of the Mundorf caps I purchased at a stellar discount, and then only because I couldn't find the ones NP used.The hookup wire is Kimber, the RCAs are Cardas and the switches are NKK. These aren't the cheapest parts, but are far from the most expensive. I'm not sure the unit would sound much different if I used more or less expensive parts. In fact, I'm a little amazed at how little sound signature the B1 has. NP noted that some folks find passive pre's lifeless in sound quality, but I don't find that in this case.
The B1 and the ACAs were my first builds. I think the jump in the learning curve from the ACAs to the B1, which is very easy, had more to do with learning how to pick parts from Mouser, follow a BOM and other minor skills not needed with a project like the ACAs.
I'm very happy with my little DIY system. Now I"m off to try a few more complex projects like the Pearl 2 and the AJ. I've caught the DIY bug and really enjoying learning about how the electronics "work" and the simple pleasure of putting something together with my own hands.
Thanks again to Jim and Gianluca!
Attachments
As to lifelessness and the B1 I think it is entirely related to all the ancillaries. I was never quite happy with it driving F5 in the system it was in....seemed like I needed more throttle that a pre with gain gave.
Driving my BA3 amp which has more gain, I never noticed so much.
In my vinyl system with Pearl 2, I substituted B1 for usual pre with no problems either.
Pearl has plenty of gain, and even though power amp was F5 at time, ( or was it BA3?) there was plenty of drive.
In systems without a lot of gain and somewhat inefficient speakers, even though plenty "loud" something seemed missing that pre with gain returned.
Will vary from setup to setup and user to user. In proper setup, all is fine with B1, or at least that is how I sense it in multiple systems here.
Russellc
Driving my BA3 amp which has more gain, I never noticed so much.
In my vinyl system with Pearl 2, I substituted B1 for usual pre with no problems either.
Pearl has plenty of gain, and even though power amp was F5 at time, ( or was it BA3?) there was plenty of drive.
In systems without a lot of gain and somewhat inefficient speakers, even though plenty "loud" something seemed missing that pre with gain returned.
Will vary from setup to setup and user to user. In proper setup, all is fine with B1, or at least that is how I sense it in multiple systems here.
Russellc
