B1 Buffer Preamp

Ex-Moderator R.I.P.
Joined 2005
I really like the look of veroboards:D
and now is the time to try it
might be something like this
a lot of work for a couple jfets :p
but its diy, and having fun :)
 

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6L6

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Joined 2010
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Laurent - My most sincere thanks, and a hearty congratulations on your completed project!


To those not familiar with Laurent's project, it is a single chassis implementation of a B1, a digital-controlled attenuator with front panel display, and the active crossover for the Linkwitz Orion speaker. Each module has it's own discrete regulated power supply. Wow!

IMG_3394.jpg


IMG_3398.jpg
 
Ex-Moderator R.I.P.
Joined 2005
Audio GD supplies. Nice :)

looks like very skilled people
seems to be mostly plug and play stuff

but also a bit like they throw in a lot of components, just for the fun of it
but maybe it does make sense
I'm not clever enough to know anything about it
I like the KISS method better, for obvious reasons :D

btw, how important is low ESR caps, to the power supply in with a preamp :confused:
or maybe its even better to not use low ESR caps ?
 
I'm not saying you should go buy it, I was just recognizing the power supplies in that build 6L6 posted. I think they will supply max 800mA as is and up to 1.5A. Its actually about the same price to build than most regulator based circuits assuming you would put a sink on your regulator and use some decent caps for filtering. Uses 2sa970 and its counterpart as well as 2sc5170 and 2sa1930. BC639 I think to.
A lower ESR I believe will do a better job filtering anything that happens by that isnt DC. I think thats why lower ESR but I am probably wrong about that.
Any noise in the power supply can make its way into your signal in a preamp, since just like an amp active preamps modulate the supply rails.
 
Hi,

I didn't think 6L6 would post the pictures, I would have made an effort otherwise and made some clearer ones!
I am a beginner in DIY and still have plenty to learn, forums like this one are really helpful.
I did use a Lite Audio chassis indeed, 59 euros here, and apart from 4 screws out of maybe 30 not fitting in the holes, I feel the quality is fair, you cannot obviously compare with chassis that retail for more, although I bought a chassis in France once for 80 euros that was absolutely rubish, returned it straight away.
I used 2 Audio GD PS, well spotted! they retail for 32$ and the build quality is good, it was a no brainer to be honest! But there are no measurements on their website so cannot comment on the performance, although they are very silent. I have an Audio Gd Dac and I am most impressed with it, they seem to specialize in overkill PS for all their designs, some of them having 13 filtering stages..

The B1 is hidden under the R2R volume control as I tried to keep everything close to the RCA and avoid long runs of cables.

Thansk again to everyone here.

Cheers

Laurent
 
hmm, to save money, I'm thinking about a box design like this
stacked wood with air between the plated
as such it could be a dust collector too :eek:


I am a complete noob, but I do believe the sound and background was much quieter when my preamp was enclosed in a full metal box as compared to with an open lid. Maybe due to some EMI/RF shielding? Therefore I would always use a metal box for preamp, never wood.

Will be interesting to hear if the seasoned ol' hands on diyaudio subscribe to this view?

--G
 
The 2 biggest deals with picking up noise are low impeadance inputs and short lines, cables etc.. And, gain.
If your preamp is <2X-10X(6-20db) don't worry about the gain part. Conversly if you have a 60db phono pre...
Longer lines/cables are like an anttena that has more sensitivity. The longer it is the more voltage it has on it.
The lower the input impeadance, the less voltage developed at the input. You really only need external sheilding with high gain circuits IMHO.
Proper grounding is ussually much more difficult to figure out...
 
Ex-Moderator R.I.P.
Joined 2005
found some faults in my front wood
makes it much more interesting
tho it may have a story less nice
will be exciting to see if it stays that way

and a few more things to complete the front design
I probably spend too much time on those details
but I find them important
 

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Ex-Moderator R.I.P.
Joined 2005
Those beautiful Bulgin......

it is indeed
and the other plastic one, with the funny name OTTO, isn't cheap either
quite sophisticated contact tehcnology

both of them should handle 2.5/A with 250Vac

but for the time ever I want to try a front mounted power switch
basicly because of the LDR's, that shouldn't be 'forgotten' with power on

btw, getting closer to a layout I hope will work well
I thought this would be easy, yet seems there's still a long way
well, I have decided to use Panasonic FM caps
 

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