B1 Buffer Preamp

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#2,102
chrismercurio said:
That's a nice case. Save your money for better parts maybe...but I like it.
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Thanks chris, i just bought a whole wack load of parts, pretty much quantitys of 40& Up for each item, ie plugs panel mount and solderable ones, stand off's leds resistors etc etc 🙂 Now to find a knob for this chassis.


I still REALLY like this one tho,

ga-9all_1.jpg
 
#2,105
All, Did we come to a consensus to modify the values of R102, R104, R202 & R204 from 1K to 221ohm for improved sound? Thanks, Tom
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sq225917 said:
Tom, yes. it works, tighter Bass with a touch more drive.
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would greatly appreciate your reasoning for lower the values. since there
is no gain, I'm scratching my head as to why the lower values help.

are these lower resistor values dependent on coupling cap values?

thanks 😉
 
#2,107
Newbie question- conceptual rather than DIY

I am rebuilding a system after a number of years out of the hobby. I am interested in the B1 but I want to understand why it improves sound quality. I have heard the pre to passive difference. I understanding their is no gain in the B1 and impedance matching is the goal but please read on.

Take two scenarios-Cd player to B1 to amp VS Cd to integrated amp. My understanding is that typical Cd player (not tubed or nos, correct me please) has a typical output impedance of .3 to .5K. The B1 as originally designed has an output impedance of 1K although some have modded it to have a .1 to .2K final resistor.

My understanding is that a 50K pot would be fairly typical for an integrated amp. So would not the Cd player to intergated amp be capable of driving longer interconnects? Is the 50K pot in the intergrated amp to a inch or two of wire to the following electronics the issue?

I am not questing Mr Pass or anyone here. A involved electronics explanation would go over my head but i would appreciate someone getting me into the ballpark. Thanks John
 
#2,109
jleaman said:
Ill try this, soon, Im having hard time looking for the 1ohm@3watt resistor, im not buying 10 or more only need 1 🙁 and im not spending 30$ for 2 15,000uf caps either.

I will change / modify the values of R102, R104, R202 & R204 from 1K to 221ohm to see if there is a difference.
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I have a bag of ~100 that probably has ~90 left. The are KOA Speer (Kiwame)...send me a pm with your address.

Chris
 
#2,112
mantisory said:
Hi all,
So, I am just wondering...how do I translate CW, W, and CCW to Ground, Input and Output on my DACT volume control?
Thanks for any assistance.
byron
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😛

CCW is the first lead, w is the center pin & cw is the final wiper lead.


Like this one,

An externally hosted image should be here but it was not working when we last tested it.




1 would go go ccw 2 to w and 3 to cw
 
#2,114
PSz. said:
Bengali,

Lower values of R104 and R204 provide a lower output impedance with the risk of oscillations if you go too low.

best regards,
psz.
Click to expand...

Thanks PSZ.

So with 221R, does the input impedance of the amp play a factor?
mine I believe is 47K. or input imped. of the amp does not matter.
anything lower than 221R will oscillate on it's own.

only the output resistors are changed? input res. stays at 1K? I'm using a 10K pot on the input side. will give it a try with the output resistors.

Have a great New Year and Decade to everyone and of course Mr. Pass! :cheers:
 
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