DIY Preamp based on B1

[anilva]

Got the long pending Preamplifier close to completion. This is based on the following:

1. HT MC Phono preamp
2. CNC MM Phono preamp
3. B1 Buffer preamp
4. Input selector switch from Ebay
5. Rotary stepped volume control based on fixed resistors
6. Regulated PS board designed by Om.

Essentially this will give 1 MC input, 1 MM input and 2 Line Level inputs with ability to electronically select the inputs and control the volume.

All assembled and tested. Everything works fine. Little tidying up the wiring is left along with few provisions I need to make for ground/earth connect for phono stage near the phono inputs. I also need to change the power switch from the red neon one to plain black one with LED indication for power. Did not have the right switch and had to make do.

Have not done full audio listening tests, but I can immediately recognize the Pass Labs character from the B1 preamp. The phono preamps are working fine. May need to fine tune the wiring paths for any hum pickup.

Thanks in full to Sachin and Om Mishra for getting me all the components and PCBs (except the source selector).

Did initial listening tests connected to the Pass F5 Turbo V2 amp. Sounds very good. Need to listen more for further fine-tuning.

Here are the pictures.

Cheers.

 

[omishra]

Thanks Anil, please let us know how it sounds. Also I am keen to see internal layout.
Once more .. Nice cabinet.
Regards.

 

[sachu888]

Hi anilva,
All your builds look very professional :clapping:
very nice looking cab.
Regards,
Sachin

 

[anilva]

Sachin/Om,

When I build my amps and preamps, I build for myself and do not focus at all on the looks except the basic ones. WAF on all my builds is '0'. I am nowhere close to Bibin's cabinets.

Similarly when I wire, I wire for functionality keeping in mind basic wiring rules on signal, power, criss crosses etc. Once they work well, then I do the trimming and harnessing of the internal wires. One of the reasons I have not shown the internal pictures is because I have not done the trimming yet. Nevertheless, I will show the internal wiring picture as well shortly.

Currently the MC phono has got OPA 2107 and the MM has 2134 opamps. The PS is set for 18VDC to B1 and 12-0-12 DC for phono stages. I hope the voltages are correct.

Cheers.

 

[sachu888]

Hi Anil,
Yes Voltages are correct.You can increase B! voltage upto 23V.I am running my B1 on the same voltage.

Regards,
Sachin

 

[bijinmb]

Hi Anil,

Wonderful to see that our FM's Pass B1 eggs are hatching one by one!

Spectacular work as usual from you.

 

[spirovious]

Its nice to see so many DIY projects,congrats anilva.

 

[murali_n]

Hi anilva,

Congrats on your build,

I suggest that you put 49990 OpAmps in all ckts since, it is the best sounding ever, I heard. :licklips:

Just my Rs.2/-

N.Murali

 

[vin_eme]

Anilva,

one small suggestion, you can drill 3mm holes in the front face place for the source selection LED's, it would look cool. Also this can indicate which source input is switched one.
Just my few cents

cheers
Vincent.

 

[sann]

Wow, I am eagerly waiting to complete my F5 to listen to B1-F5 combo, please update with the listening impressions.
Regards,
Sann

 

[sann]

I suggest that you put 49990 OpAmps in all ckts since, it is the best sounding ever, I heard. :licklips:
N.Murali

Hi Murali,
I have been experimenting with LM49990 since last few days, have kept it constant in SSP before B1, and rolling in CNC, whatever combo I try, I fall back to 49990-->49990, however last night I discovered that LM49990-->opa2134, gives more weight and clarity to vocals with slightly better imaging.
What you guys feel?
Regards,
Sann

 

[bibin3210]

Sachin/Om,

When I build my amps and preamps, I build for myself and do not focus at all on the looks except the basic ones. WAF on all my builds is '0'. I am nowhere close to Bibin's cabinets.

Similarly when I wire, I wire for functionality keeping in mind basic wiring rules on signal, power, criss crosses etc. Once they work well, then I do the trimming and harnessing of the internal wires. One of the reasons I have not shown the internal pictures is because I have not done the trimming yet. Nevertheless, I will show the internal wiring picture as well shortly.

Currently the MC phono has got OPA 2107 and the MM has 2134 opamps. The PS is set for 18VDC to B1 and 12-0-12 DC for phono stages. I hope the voltages are correct.

Cheers.

It is really nice looking cab.....a clean classic look......but what distract me is those two knobs and the red switch.

If you can change those knobs to some metal knobs with flanges and as you mentioned plain black switch, it looks awesome.

Thanks,
Bibin

 

[josephjohnt]

Great build Anil. Congrats. The side grill on the cabinet looks impressive. What cabinet are you using?