[rtate]

Just to report back on the dual pec pot, I took some measurments and the results are a bit concerning to say the least   

At 200 ohms there was a difference of 60 ohms
At 1K there was a difference of  250 ohms
At 20k there was a difference of almost 3k

I can't imagine that this wouldn't be audible!!!!
At this point I think I will order one of the stepped volume controls.....

[Jon L]

It's absolutely crazy, but I seemed to have bought yet another preamp, the Diyparadise Eva LDR 



Now I have my tweaked-out Transcendant Grounded Grid tube preamp, almost-tweaked-out Pass B-1, and a LDR preamp, which I assume will not have much to tweak. 

It's crazy because I run my system source-direct most of the time without a preamp, and so far preampless sounds "best" to me.  I guess I can have fun having my own preamp shoot-outs after each parts upgrade 

[wushuliu]

Jon L, thanks for posting the pics.  What B1 board are you using?  Doesn't appear to be a standard Pass B1 board.  Did I miss something?

What's the benefit of using 330R value?

Thanks!

Lower outpuit resistance has been found to increase clarity and dynamics. However you don't want to go too low or you risk oscillating your amp. The stock DCB1 recommends 220 ohms for instance; 330 ohms is the lowest I've tried and therefore the lowest i recommended at the beginning of this thread.

[roymail]

Lower outpuit resistance has been found to increase clarity and dynamics. However you don't want to go too low or you risk oscillating your amp. The stock DCB1 recommends 220 ohms for instance; 330 ohms is the lowest I've tried and therefore the lowest i recommended at the beginning of this thread.

AC, the (4) 1K ohm resistors on the B1?

[wushuliu]

AC, the (4) 1K ohm resistors on the B1?

Yeppers

[wushuliu]

It's absolutely crazy, but I seemed to have bought yet another preamp, the Diyparadise Eva LDR 



Now I have my tweaked-out Transcendant Grounded Grid tube preamp, almost-tweaked-out Pass B-1, and a LDR preamp, which I assume will not have much to tweak. 

It's crazy because I run my system source-direct most of the time without a preamp, and so far preampless sounds "best" to me.  I guess I can have fun having my own preamp shoot-outs after each parts upgrade 

Nice price on that too...

[Jon L]

Nice price on that too...

I know.  I can sort of see LDR volume-control integrated with B1 or DCB buffer in one box for REALLY nice preamp 

BTW.  Do you think just bypassing the volume pot in B-1 and soldering together input wire with output wire would be OK?

[Russtafarian]

BTW.  Do you think just bypassing the volume pot in B-1 and soldering together input wire with output wire would be OK?

That'll work Jon.  But keep in mind you may be changing the input impedance of the circuit by removing the pot.

[roymail]

I know.  I can sort of see LDR volume-control integrated with B1 or DCB buffer in one box for REALLY nice preamp 

BTW.  Do you think just bypassing the volume pot in B-1 and soldering together input wire with output wire would be OK?

Hey Jon,  I raised the same question back on page 25, post 489.  But, I'm still not real sure about it.  The Burson Buffer doesn't have a volume pot, just rca's.

[Jon L]

That'll work Jon.  But keep in mind you may be changing the input impedance of the circuit by removing the pot.

That's why I ask, Russ.  Wondering if I need to solder on some resistors instead of pot, and what do I do with the green ground wire soldered to the pot?  Leave it on the pot or solder it on to some random ground point on the board or chassis?

[Russellc]

It's come up several time on diyaudio.com. Doesn't mean yours won't be fine, but better safe than sorry. If you haven't used them yet, it's easy to do returns w/ digikey...

http://www.diyaudio.com/forums/chip-amps/40676-so-i-did-try-all-those-different-potentiometers-25.html#post807128

Just exchange for the mono pots from PEC, they work fine. It's what Nelson uses in the commercial version.

Russellc

[exojam]

Well the wall wart should be arriving today. Then I will find out if I hooked everything up correctly.

One thing has me thinking though. Right now my speakers are different length away from my listening position due to room layout. With the Onkyo I have the trims a little different to get 75db at the listening position. I hope that one side will not sound louder than the other through the pre amp.

James

[sondale]

Hey Jon,  I raised the same question back on page 25, post 489.  But, I'm still not real sure about it.  The Burson Buffer doesn't have a volume pot, just rca's.

Roy - have you tried it yet?

Alan

[roymail]

Alan,  I haven't tried it yet, just one of many things I haven't gotten around to doing.

[exojam]

Well I got the wall wart in and hooked up the B1. No left channel! Took it back out to the garage and found the left wire had come off of the RCA. Fixed.

First up were Robert Plant and Alison Krauss “Raising Sand”. On this album I noticed the vocals had even more separation than before, also the instruments were more defined. Next up was Willie Nelson. This also sounds very clear and all vocals and instruments were available to listen to separately or “all together” if that makes sense.  I suck at describing what I hear so I apologize about that.

What I found interesting is that I could tell a difference in the material, not an absolutely huge difference but a change for the better none the less, but my mother in law yelled out to me while listening to the WN album and asked why I turned it down. I called her out to show her the B1 and she commented on how she was able to listen to every instrument in the band and the vocals and thought it was fantastic.

The one bad thing about the way I made mine is that the sound from the right speaker gets to my listening position before the left due to the way the speakers sit in the room. With the B1 (as I have it) I cannot control this since I am using a single pot.  This was something I did not think of before going this route, so I guess I will just have to change the area I sit in while jamming.

All in all very happy.

[Russtafarian]

@JonL: If the pot is hooked up in the usual way (not as a shunt volume control) you can replace it with a resistor of the same value as the pot.  So if it's the 10k Alps pictured below, replace the pot with a 10k resistor for each channel.  You don't need to do anything with the ground wire other than make sure it doesn't touch and potentially short anthing else in the circuit to ground.  if you're not going to use a pot at all, remove the ground wire from the board.

[Jon L]

@JonL: If the pot is hooked up in the usual way (not as a shunt volume control) you can replace it with a resistor of the same value as the pot.  So if it's the 10k Alps pictured below, replace the pot with a 10k resistor for each channel.  You don't need to do anything with the ground wire other than make sure it doesn't touch and potentially short anthing else in the circuit to ground.  if you're not going to use a pot at all, remove the ground wire from the board.

Thanks Russ.  Will try that, but I'm beginning to think what's stopping me from soldering some good wire from my soon-to-arrive LDR attenuator's output right onto the B-1 board.  Bet that sounds fantastic 

[roymail]

Riddle me this Joker....whats GREEn with envy, cant get hard and loves taking a stiff horse cock in the arse? Why John R it be! Aaaargh hes a faggy pirate. Aaaargh!
haha John R u loser tigtey whitey tight ass!

The Man

Matt, you should soon see the inside of the intergalatic wastebin, a place for all those who don't play nicely!  Real men know when to behave. 

[exojam]

Here is a picture of the final outcome. I like the small foot print of it now but once that last hermit crab on the other shelf goes to see Davey Jones than I will make a better housing.

I also forgot to say thanks to Pass Labs for making this available and to all those who helped me get a finished B1!



James

[Nick77]

Well i just i would post a couple of pic's since i am totally finished with this B1 project. Cleaned up some wireing and installed Gen2 bypasses and with the new naked Vishays it rocks!!