B1 Buffer Preamp

[marc brown]

I'm looking at transformers and they rate them for the secondaries wired in parallel and series -- with series having twice the voltage rating.

How do you wire them in parallel? How about series? I looked online and couldn't find any wikis.

Is the B1 better off with 18V or 9V + 9V?

thanks for the help

 

[Babowana]

Is the B1 better off with 18V or 9V + 9V?

I know that B1 will work happily if receives 18-24VDC from any external power supply.

I understand that you are going to use a transformer having 2 x 18Vac secondary (18Vac in paralleling) or 2 x 9Vac secondary (18Vac in series), to get the recommended 18-24Vdc. And, I think that anyone is equally okay.

Hoping I understood your question correctly . . .

Cheers,

>><<

 

[troystg]

I'm looking at transformers and they rate them for the secondaries wired in parallel and series -- with series having twice the voltage rating.

How do you wire them in parallel? How about series? I looked online and couldn't find any wikis.

Is the B1 better off with 18V or 9V + 9V?

thanks for the help

This would work...


http://www.parts-express.com/pe/sho...165 &FTR=&CFID=4668909&CFTOKEN=27301370

 

[vdi_nenna]

This would work...http://www.parts-express.com/pe/sho...FTOKEN=27301370

"No load voltages can be up to 50% higher"

Mr Pass said it can deliver higher voltages under no load. See last sentence in description on site.

I suggest that the R1 power resistor be made a little larger to provide some more filtering, since the supply is unregulated. Maybe 5 ohms
at 3 watts.

 

[merlin2069er]

power switch?

Just wondering if I should add a power switch to the B1. I know it wouldn't hurt.


I'm also conflicted about getting great hookup wire for the B1. Please let me know what a reasonable quality and gauge would be.

Thanks,
JG

 

[labjr]

Re: power switch?

Just wondering if I should add a power switch to the B1. I know it wouldn't hurt.


I'm also conflicted about getting great hookup wire for the B1. Please let me know what a reasonable quality and gauge would be.

Thanks,
JG

If you look on partsconnexion there's all kinds of hookup wire.

http://www.partsconnexion.com/catalog/wire.html

KIMBER TCSS is only about $1 ft. You can go crazy with AGSS silver wire but it's expensive.

 

[troystg]

Steve @ Apex.jr has Silver plated copper with Tefl#* (the DuPont guys are still banning the use of that word) insulation in various gauges and colors..

 

[Tea-Bag]

I think for B1 signal wire (RCA's volume pot) anything 28ga and below is good. Too big is what won't fit into the hole.
of course I prefer a good clip lead until I have all the nuances figured out.

 

[scranton]

B1

This is a remarkable component. I have had it in place of my old modded 565 adcom preamp for a couple of weeks. With a 555 adcom amp and open baffle speakers I can't believe the quality of the sound.

 

[Melon Head]

Its excellent to see someone reporting back good results with this preamp.

 

[Melon Head]

LT Spice

I am learning LT Spice at the moment.
So I decided to a spice model of the B1.
However looking at the distortion profile, their is mainly 3rd Harmonic distortion with no 2nd Harmonic.
This seems a little strange as I didn't see Nelson talk about their being any 3rd Harmonic.
Anywy has anyone else modeled this circuit?

The way I measured it, was with the following parameters (feel free to correct me on anything):
- Voltage input amplitude of +/- 1V (ie 2V p-p)
- Volume setting at 12 O'clock using 25k linear pot
- Load = 47k resistive load
- DC Power = 18V

I am a little unsure of the CD Player spec. Is it 2V rms, 2V amplitude, or 2V p-p?

Anway have a look at the attachment.

PS This is an awesome tool for understanding circuits.

 

[Melon Head]

Sorry about the attachment. I'll have to shrink the file size down.

 

[folkeb]

I've just finished my cardboard box version of the B1, using NP's DIY board. I have mostly used standard components with the exception of my favorite film caps - obbligato. The 10uF are rather large so it doesn't look as neat as the original does, but who cares about looks! The only pot I had laying around was a 50k alps, but I understand that some prefer lower values. I know that my DAC sounds better with 10k than 50k in my aleph P (SE version with 10k on the input).

So far the sound is impressive, and I am not certain if I want to reconnect my aleph P. Now I need to improve the PSU...I've just done it real simple - a 22000uF after the rectifier brigde.

Thank you mr. Pass yet again!

 

[Salas]

Re: LT Spice

I am learning LT Spice at the moment.
So I decided to a spice model of the B1.
However looking at the distortion profile, their is mainly 3rd Harmonic distortion with no 2nd Harmonic.
This seems a little strange as I didn't see Nelson talk about their being any 3rd Harmonic.
Anywy has anyone else modeled this circuit?

The way I measured it, was with the following parameters (feel free to correct me on anything):
- Voltage input amplitude of +/- 1V (ie 2V p-p)
- Volume setting at 12 O'clock using 25k linear pot
- Load = 47k resistive load
- DC Power = 18V

I am a little unsure of the CD Player spec. Is it 2V rms, 2V amplitude, or 2V p-p?

Anway have a look at the attachment.

PS This is an awesome tool for understanding circuits.

I did run some actual FFT through B1 when I made mine and the even order was dominating odd order in all orders. It also distorted the less, the more I turned the volume clockwise.

CD is about 6V P-P.

 

[labjr]

Re: Re: LT Spice

I've just finished my cardboard box version of the B1, using NP's DIY board. I have mostly used standard components with the exception of my favorite film caps - obbligato. The 10uF are rather large so it doesn't look as neat as the original does, but who cares about looks! The only pot I had laying around was a 50k alps, but I understand that some prefer lower values. I know that my DAC sounds better with 10k than 50k in my aleph P (SE version with 10k on the input).

So far the sound is impressive, and I am not certain if I want to reconnect my aleph P. Now I need to improve the PSU...I've just done it real simple - a 22000uF after the rectifier brigde.

Thank you mr. Pass yet again!

Are there any B1 boards currently available? Or maybe you made your own?

 

[Melon Head]

Thanks for that Salas.

Did you use LTSpice to do your FFT measurents, or were they real measurements performed with a distortion analyzer?

Anyway here is the attachment.

 

[jameshillj]

Don't forget that the final SOUND depends a lot on those Series Signal capacitors AND the power supply. [don't skimp this].

 

[AndrewT]

Re: Re: LT Spice

I did run some actual FFT through B1 when I made mine and the even order was dominating odd order in all orders. It also distorted the less, the more I turned the volume clockwise.

CD is about 6V P-P.

yes.
Upto 2.2Vac = 3.1Vpk = 6.2Vpp

 

[Salas]

Thanks for that Salas.

Did you use LTSpice to do your FFT measurents, or were they real measurements performed with a distortion analyzer?

Anyway here is the attachment.

Real.

 

[Melon Head]

Do you have any idea what I might be doing wrong?
Or is this a common problem with simulators?