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Roll Call: Who's building, built, or thinking of building a beta22?
Jan 20, 2011 at 3:36 PM Post #2,851 of 3,218
Nice build, LeMat. What did you use for the cases? The volume knob looks like a GoldPoint, but how did you fashion the lighted ring?
 
Jan 20, 2011 at 3:47 PM Post #2,852 of 3,218


Quote:
chronomitch said:
Nice build, LeMat. What did you use for the cases? The volume knob looks like a GoldPoint, but how did you fashion the lighted ring?
Click to expand...


Cases are from Hifi2000. Took a while to get these, with very little communication, but it's very well made, and perfectly packaged (each plate is wrapped into thermo-plastic)
 
Volume knob and attenuator are indeed from goldpoint.
 
Lighted ring "how to " has been very well explained here : http://www.head-fi.org/forum/thread/85561/post-pics-of-your-builds/7710#post_7207929
 
Only difference, I used only one disc of frosted perspex.
Holes are sized so I can "plug-in" 5mm LED.
 
Feb 27, 2011 at 3:55 PM Post #2,853 of 3,218
I have a persistent problem guys. I had a board before that didn't measure correctly on R10, R11 and R12. They measured 1 volt lower than R9. So I gave up and got a prebuilt board thinking I would save some time and effort. Sure enough, the board works, but looks horrible and nothing even remotely like the other boards I have. So I bit the bullet and bought a new set from Jeff Rossel and lo and behold, that board has the same problem as my first one :frowning2: Any ideas would be most helpful since I cant really find anything obviously wrong with the boards.
 
Mar 8, 2011 at 12:59 AM Post #2,855 of 3,218
sphinxvc said:
 
I was pondering building a 2CH Beta to start out with and then eventually making it a 4CH in the future - what gain is optimal?  (The gain is locked and unchangeable, correct?)
Click to expand...

I built a 3-channel Beta 22 with a gain of 5 for the boards, and it is more than loud enough for anything I have tried it with (HD800, HD650, LCD-2). Remember that when you go balanced, the gain is doubled. So if you use a gain of 5 for each board, using them in a balanced configuration would yield an effective gain of 10.
 
It's not the end of the world if you need to change the gain of your boards, as you only need to change two resistors (R3, R4) and four capacitors (C2-C5).
 
Dec 27, 2011 at 1:51 PM Post #2,857 of 3,218
Jan 4, 2012 at 4:09 AM Post #2,858 of 3,218
Jan 8, 2012 at 5:13 PM Post #2,859 of 3,218
 
My first post of many in this thread - hi all and thanks in advance for any help! We'll start with a hopefully relatively easy one...
 
Quote:
amb said:
Quote:

Originally Posted by johnwmclean /img/forum/go_quote.gif
AMB, since on the subject of gain I have a question.
I'm building a dac that outputs 4Vp-p in balanced, my Beta 22 is set to 2 total 4 in balanced, driving 650's.
Do you think I have an issue with these gain settings?


4Vp-p is only 1.4Vrms and should not be excessive with the HD650 on a low gain amp.

EDIT: I hope you really mean 4Vp-p, and not 4Vrms. If the latter, then the gain might be on the high side. Only way to know is to try it, I guess.
Click to expand...


 
I am planing to build a beta22 with balanced functionality for use with a Cambridge Audio DACMagic, which says it puts out 4.2 V rms when balanced (2.1 V unbalanced). Yes, rms. This is going to be too much even for gain 2, no? Primary headphones are HD650s.
 
 
Jan 8, 2012 at 6:26 PM Post #2,860 of 3,218
Well if you are doing balanced (4 board) then a gain of 2 on each board turns into a gain of 4. I would say that is a bit high with such a hot source. A single ended with gain of 2 would probably be fine though. If you are set on building a balanced amp, I would spend the money on a good stepped attenuator, or better yet build amb's delta 1 attenuator. This will give you excellent channel balance even at high levels of attenuation that you will need.
 
Jan 8, 2012 at 8:33 PM Post #2,862 of 3,218
The value of the attenuator is not too important. Anything from 10k to 100k would be fine probably. I have used 25k in most of my builds. Like I said though I would build amb's delta1 if you can swing it for the excellent channel matching and other features.
 
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