B1 builders thread

[richluvsound]

I took the pot and selector out and got it working with my phone as a pre .

The boards are fine and probably the way I wired the pots and selector thats causing me grief . No panic . I want to get the Pearl finished and drop back to this later .

thanks ... Rich

 

[dejanm]

Pass B1 as a buffer ...

The resistors are Caddock, input caps are Auricap and on the output I put BlackGates STD 200 uF. Output resistor is 50 Ohm instead of 1 KOhm. For balancing conversion I use really excellent Jensen transformers. 10 mF Mundorfs are in the supply, 1 Ohm resistor is Mills and wiring is silver-gold Mundorf wire.

Connectors are silver WBTs and XLR Furutech. IEC is also Furutech. Power supply is regulated with LM317 for 24 V DC. Transformer is 20 VA. (the other one is for supply of relays of my passive TVC).

It works really well ...

 

[Marra]

Nice work dejanm. Do you use the buffer before or after the TVC?
I would be very interested in seeing info about the relay switching of the TVC's if you care to post.

 

[dejanm]

Nice work dejanm. Do you use the buffer before or after the TVC?

I am using it after the TVC in order to reduce the impedance of the TVC.

I am using copper S&B transformers of the third generation in my TVC preamp. It has 24 positions of about 2 dB attenuation per position. Output impedance varries depending on the position but in average it is about 1 KOhm or a bit more than that. Now, after exchanging 1 Kohm output resistor of original Pass schematic with 50 Ohm one in this buffer, I have output impedance of about 100 Ohm.

I would be very interested in seeing info about the relay switching of the TVC's if you care to post.

Here it is:

 

[Marra]

Thanks dejanm I was hoping that you might post the information for the relay switching for the TVC; perhaps starting another thread so as not to take over this one. I too am using the S&B mk3's but havent tried it with a buffer as yet.

 

[6L6]

Wow - that's a beautiful project.

Thank you for the schematic of your switching, the SE to Balanced connections are of particular interest to me.

 

[richluvsound]

Thank you also for your drawing .... makes things a little clearer for someone
like myself just starting out .

Nice looking project , Rich

 

[dejanm]

Unfortunately Marra I do not have it anymore (TVC was finished in 2007). I only have this picture - maybe it can be of any help ... I ordered this PCB - it was done by profi's not by me ...

[/IMG]

Basically the implementation is straight-forward connecting the switches and Shallco selector with the relays ...

 

[Marra]

Thanks. I don't suppose you know if the relay boards are still available?

 

[dejanm]

Thanks. I don't suppose you know if the relay boards are still available?

I can connect you with the guy who made them for me so you can make a deal (or not) directly with him ... if you want. Send me a PM if you need more information.

 

[richluvsound]

I have never used these audio drivers before , are they polarised ?

I'm guessing they are and the dot on the board should match the dot on the part ?

http://www.farnell.com/datasheets/1360574.pdf

 

[AndrewT]

Hi,
balanced signals have two phases that are 180degrees apart.
If the half signal drops below +0.0V then this requires a dual polarity supply.

If you are asking can the chip be swapped around in it's socket, then no. All dip 8 chips have a marking indicating PIN1. This must be aligned with the PCB correctly to allow the chip to get the correct signals on all of it's pin.
The only chip I am aware of that does not get destroyed by inverting it in it's socket is the 741.

 

[richluvsound]

Thanks Andrew ,


I found a photo showing the correct orientation - it appears my guess was correct .

I have managed to make a supposedly simple build even more complicated . The great thing is , a few have been there before me .
I would advise everyone on the forum to buy shares in solder wick 😉

Rich

 

[bassnkeys]

My B1

I've posted my B1 at bassnkeys.

 

[6L6]

The photo you have posted currently looks like an old Onkyo cassette deck...

???

 

[bassnkeys]

There is a B1 in there with a Goldpoint stepped attenuator. If you click on large image a description comes up.

 

[richluvsound]

I have been thinking about using this for my Balanced B1 .... opinions are welcome please ?

Glasshouse Takman metal stepped attenuator Hifi Collective


Rich

 

[albertNL]

I have been thinking about using this for my Balanced B1 .... opinions are welcome please ?

Glasshouse Takman metal stepped attenuator Hifi Collective


Rich

I have bought the same (also for a B1) but Jaap (my friend who does the building for me) is still working on my F4's. Have no idea how they will sound.

 

[richluvsound]

Thanks Albert , that gives me confidence .

 

[Marra]

Balance XLR 23 Step Attenuator Potentiometer 20K Log | eBay

These work well to. I used a stereo version in my DCB1 before switching to an LDR attenuator.