Pass B1

[omishra]

I agree on the quality part i.e. purity of copper strands. What about shielding?
Is it required or not?

Shielding is required whenever there is probability of intrusion to signal. Here once signal enters inside the box, nothing can interfere from outside. All TT phono wires and PS are kept away from line level wires. Internally all bare wires can not talk to each other unless -

1. They are unterminated, can act as antenna. This is not case here.
2. They are at different level of same signal, can interfere the poor among them. This is not case here. Only phono wires needs protection but I moved them away quickly to another partition. It saved.
3. They are different signals all together. This case, whenever signal lines are running parallel, they can induce each other at very minute levels of few micro/pico volts and get rejected by line level circuitry.

In my implementation I am not running any ground wire along with signal. They are single strand of live wire. Grounds from in/out and PCBs are running towards PS only. Though B1 make ground contact to chassis, that's only place it is. No other ground current among other modules. That's secret of silence - No ground loop and no cross talk inside the box.

 

[quad]

Hi Sachin / Omishra,

During cellar cleaning up I came across CANARE cables of different lengths (0.5M-2.0M). PM your addresses to me, I will ship them to you. I know they can be more useful to you guys.

Great offer, and a very well deserved one.
These two guys are doing a great job for the audio DIY community,

 

[gopib]

+1 to quad's reply.

Sachin and Omishra you guys are wonderful.

 

[kroyin]

If you want to make your B1 2.1 (if you have a active subwoofer with L-R input) then you can do it

Q>Can I drive the sub direct from the CD player (with or without a resistive splitter) or do I need to build a second B1 buffer for this?

Pass Answer>I would try it either direct or by splitting the output of the B1 and
see what works best - both approaches have the potential for
working fine.

Actual implementation (blow up the pictures in Post 2573)

B1 Buffer Preamp - Page 258 - diyAudio

 

[Audiodoc]

I have used my B1 as 2.1 by using one input and two (parallel outputs) one to the power amp driving my Wharf 10.1s and one to my Wharf SW150 subwoofer. It works. Just select an adequate crossover frequency in the sub depending on your speaker.

 

[doors666]

I have used my B1 as 2.1 by using one input and two (parallel outputs) one to the power amp driving my Wharf 10.1s and one to my Wharf SW150 subwoofer. It works. Just select an adequate crossover frequency in the sub depending on your speaker.

This would work as long as your speakers can handle full range signal. otherwise a high pass would be needed to filter out the lf from signal to speakers.

Has anyone tried to use pass b1 as a headphone amp?

 

[Audiodoc]

Since it has unity gain it wont work as an amplifier as such, however one may try it with iems or sensitive headphones.

Wharf 10.1 handle almost the entire spectrum from 40 -20k so not a problem in my case. However others may need a crossover as you mentioned.

 

[captrajesh]

Unless the speakers are part of a sub-sat / active system, all speakers, big or small, have their own passive crossovers to adequately protect them from playing beyond their capabilities. Then where is the need for providing a separate hi-pass filter?

Another thing; the B1 is a no gain buffer pre. How it can act as a headphone amplifier?

 

[cmsajith]

Unless the speakers are part of a sub-sat / active system, all speakers, big or small, have their own passive crossovers to adequately protect them from playing beyond their capabilities. Then where is the need for providing a separate hi-pass filter?

Another thing; the B1 is a no gain buffer pre. How it can act as a headphone amplifier?

to avoid the frequency overlapping or peaks due to multiple speakers reproducing the same frequency.

 

[Audiodoc]

In my case the wharfedale 10.1 can reproduce from say 40 hertz to 20000 hertz. What we want to know is the -3 dB point of the front speakers. Then set the subwoofer cut off little higher say 60 Hz in this case. Thereby extending the low frequency response of your system. Usually I fell my bookshelves have enough bass for most of my musical needs however the sub provides the essential low frequency punch in many bass heavy tracks.

 

[doors666]

Unless the speakers are part of a sub-sat / active system, all speakers, big or small, have their own passive crossovers to adequately protect them from playing beyond their capabilities. Then where is the need for providing a separate hi-pass filter?

Another thing; the B1 is a no gain buffer pre. How it can act as a headphone amplifier?

No captain, none of the speakers come with low freq protection. the woofer is protected from higher frequencies, but not from low frequencies. e.g. it might be protected from going above 2500hz, but not from handling say below 30hz. If a ported speaker has its port tuned to say 30hz, and you feed it strong content at 20hz, that is below its tuning freq, the port unloads (works against the woofer instead of helping the woofer, woofer has to put extra effort), you will see the woofer cone going back and forth at full excursion at high speeds, eventually blowing up, not a pretty sight.

If you are interested, I can recommend a few movie scenes that will make it happen, be careful though:lol:

 

[captrajesh]

to avoid the frequency overlapping or peaks due to multiple speakers reproducing the same frequency.

I thought that one is required to dial in the subwoofer to kick in to take charge from where the speakers can't go. Isn't it so?

 

[captrajesh]

No captain, none of the speakers come with low freq protection. the woofer is protected from higher frequencies, but not from low frequencies.

AFAIK, any driver needs 'protection' to prevent it from playing below it's 'FS' by limiting the extent of exexcursion. No protection is needed for it to play the higher frequencies. The X-over stops feeding the driver higher frequencies by limiting the higher frequencies through gradually reducing the signal's amplitude and the smaller driver (midrange driver in a 3 way speaker or tweeter in a 2 way speaker) would be fed the higher frequency signals through increasing the signal's amplitude gradually so that the music is produced seamlessly, as per the designer's choice. Am I missing anything here!

it might be protected from going above 2500hz, but not from handling say below 30hz. If a ported speaker has its port tuned to say 30hz, and you feed it strong content at 20hz, that is below its tuning freq, the port unloads (works against the woofer instead of helping the woofer, woofer has to put extra effort), you will see the woofer cone going back and forth at full excursion at high speeds, eventually blowing up, not a pretty sight.

IMHO the blowing up would happen if one plays at far higher amplitude (loudness) than the speaker can handle.

 

[doors666]

AFAIK, any driver needs 'protection' to prevent it from playing below it's 'FS' by limiting the extent of exexcursion. No protection is needed for it to play the higher frequencies. The X-over stops feeding the driver higher frequencies by limiting the higher frequencies through gradually reducing the signal's amplitude and the smaller driver (midrange driver in a 3 way speaker or tweeter in a 2 way speaker) would be fed the higher frequency signals through increasing the signal's amplitude gradually so that the music is produced seamlessly, as per the designer's choice. Am I missing anything here!

IMHO the blowing up would happen if one plays at far higher amplitude (loudness) than the speaker can handle.

That is correct.
Below port tuning frequency, it will happen at a lot lesser amplitude. So is the case with sealed also. To easily understand this, think of a tweeter, it can handle some 50 wattsat say 10khz. It can also do 1khz, but it can only handle probably 5 watts. Same case with woofers.

 

[doors666]

Ok guys, I am facing some issues with my pass b1 build and the cabinet. I am in the office, so will post pics in the evening probably, briefly the issue is -
1. the rca connectors are too small for the cabinet. I got the MX ones, without the connector soldering tab, they just fall through the holes. Did I purchase the wrong ones. I thought that they are all standard size.
2. When I fit the volume control knob with the board into the volume control hole, no threads come out on the other side. There is a small notch on the volume control that prevents it from fully entering the hole.
3. The rotary input selector has similar issue, the rod goes in, but the threads dont even enter the hole, so it cant appear on the other side. can I use a toggle switch for the time being with the same hole. Are there different sizes available for the rotary ones, what do I need to ask while buying.
4. Where can I buy the screws and standoffs for mounting the pcbs in bangalore, not so easily available on SP road. what size am I looking for?
5. There are some white colored tabs that came with the cab, what are these for?

 

[omishra]

1. the rca connectors are too small for the cabinet. I got the MX ones, without the connector soldering tab, they just fall through the holes. Did I purchase the wrong ones. I thought that they are all standard size.

These MX one missing plastic isolators hence going through. Buy either neutrik or ebay one

neutrik connectors which cost almost ~200 each
NYS367-0 - NEUTRIK - SOCKET, PHONO, CHASSIS, BLACK | element14 India
NYS367-2 - NEUTRIK - SOCKET, PHONO, CHASSIS, RED | element14 India

Gold plated from ebay which cost Rs 50/pair like this.
3-Pair GOLD Amplifier Audio Terminal RCA CONNECTOR FEMALE CHASSIS Panel PCB Jack | eBay

2. When I fit the volume control knob with the board into the volume control hole, no threads come out on the other side. There is a small notch on the volume control that prevents it from fully entering the hole.
3. The rotary input selector has similar issue, the rod goes in, but the threads dont even enter the hole, so it cant appear on the other side. can I use a toggle switch for the time being with the same hole. Are there different sizes available for the rotary ones, what do I need to ask while buying.

I found this problem while looking into Swapnil's build. I suggest Swapnil to post some pics from his build which I suggested for "L' board behind the holes to mount these pots and rotary switch.

M3 threaded 0.5mm pitched spacers of 5mm length and M3 pan headed 5mm screw on top with M3 flat headed 7mm screw for bottom will do.

 

[svaze]

My build is not yet complete, however I will post a pic (later today) of how Om suggested I mount the LSA.

For the source selector rotary switch, Om helped me recess the face plate slightly (around the hole meant for the source selector) so that some of the threads were protruding out of the face plate and I could then mount the nut.

I bought some Neutrik NYS 367 connectors from Biren of Kiran Sales. He is a dealer for Neutrik products in Mumbai. You can contact him on biren at kiransales dot com. IIRC I paid 70 rupees per connector.
Or maybe you can contact the distributor of Neutrik in India to find out who is the authorized dealer in your city.

~Swapnil

 

[svaze]

Here are the pics:

The 4 holes on the left are for inserting the LEDs of the source selector board. Unfortunately the drill bit went a bit too far while drilling the 3rd hole. Will be fixing that by putting some filler and repainting the face plate.

 

[Audiodoc]

Tips for drilling.
1. Sharp quality drill bits.
2. Drill from the opposite side or use the depth monitoring rod on the drill.
3. Use some lubricant on the bit.
4. Before drilling mark with pencil followed by a hammer and nail to punch a depression so that your drill bit doesn't wander.
5. For the selector knob a special bit needs to be used otherwise you can use a switch with a long shaft.

 

[omishra]

That mistake was by me. despite all experience and above due care. Even we used masking tape to protect finish.
The wooden willow support had hole and drill went through quickly. Rubbing some burr on the plate. Looking at some jugaad tape over that.