beta22 question
Mar 17, 2011 at 7:15 PM Thread Starter Post #1 of 14

ezzieyguywuf

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Is it possible to build one that could be used as both a headphone amp and, in the future, as a speaker amp? On the website it says it can be built for either of these tasks, but I'd prefer an all-in-one solution. Maybe a gain switch or something? Or is it just not that simple?
 
Mar 17, 2011 at 7:32 PM Post #2 of 14

IPodPJ

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You can, yes.  The problem though is that most headphones will respond well to a low gain setting (especially if you are running them balanced), whereas speakers won't unless they have very high sensitivity.  Even then you'd probably want to use a higher gain setting for speakers.  You want to use as little gain as you need for headphones so that you get the maximum travel out of your attenuator.  If you have too much gain then not only will you be potentially getting excess noise but you won't be able to turn your attenuator up very far.  Unless you are using orthodynamic headphones it will be hard to get a perfect balance of both, since the Beta does not have variable gain.  If you do plan on using the amp for both, then you'll probably want to choose a gain setting somewhere in the middle, such as 5 or 8.
 
Mar 17, 2011 at 7:57 PM Post #3 of 14

digger945

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See my post below.
bigsmile_face.gif

 
Mar 17, 2011 at 8:14 PM Post #4 of 14

bcg27

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I know amb has recommended against socketing the resistors and caps that govern the gain of the amp, however if it is working fine for you then maybe it is fine. The only ortho that really needs higher gain than dynamics is the he-6 anyway.
 
Have you considered adding a pre-amp when you want to use it with speakers? A gain of 5-8 for headphones and then putting a gain of 2 or 3 in front in a preamp should handle both situations well.
 
Mar 17, 2011 at 8:22 PM Post #5 of 14

digger945

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I should note, I do not own, nor have I ever built a Beta 22. I am using the socketed method on my balanced Dynahi amp. The two are a little different. 
 
I would like to take back my suggestion to socket the resistors on the Beta22. If there should be a resistor that is not making good contact in the feedback circuit, then you run the risk of damaging the amp and any headphones plugged in. 
 
I really shouldn't make suggestions for other people, and I shouldn't make the assumption that everyone will take the same level of care in changing gain (using this method) as I do.
 
I will be deleting the suggestion in my post above.
 
Sorry about that.
smily_headphones1.gif

 
Mar 17, 2011 at 9:02 PM Post #6 of 14

johnwmclean

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Dang Scott...
 
...my tweeters just dispatched from of my Sonus Faber’s at high velocity, nearly took an eye out on the way through.
 
...any more suggestions?
 
basshead.gif

 
Mar 17, 2011 at 9:27 PM Post #7 of 14

digger945

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Seems like I have been making a lot of bad suggestions lately. I wrongly assume that everyone is as eager to experiment as I am. 
 
You would think that after so long, I would learn to keep my mouth closed and just read and observe.
 
It would be hard to put a figure on just how many parts I have blown up and made glow white hot from heat. The burning smell is terrible sometimes. Not a good way of giving advice to other people, huh.
 
Mar 17, 2011 at 10:08 PM Post #8 of 14

bcg27

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Quote:
Seems like I have been making a lot of bad suggestions lately. I wrongly assume that everyone is as eager to experiment as I am. 
 
You would think that after so long, I would learn to keep my mouth closed and just read and observe.
 
It would be hard to put a figure on just how many parts I have blown up and made glow white hot from heat. The burning smell is terrible sometimes. Not a good way of giving advice to other people, huh.

 
Nothing wrong with suggestions as long as proper cautions are also given. Personally I think that socketing the gain caps/resistors would be fine, but when the designer of the amp gives a recommendation it's probably not a bad idea to follow it. Also I had no need for variable gain so didn't even really consider the issue when I built mine. 
 
Edit: I should add that my B22 has a gain of 5 and works brilliantly both with hd600s and my newly acquired lcd2s.
 
Mar 17, 2011 at 10:20 PM Post #9 of 14

wink

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Quote:
Seems like I have been making a lot of bad suggestions lately. I wrongly assume that everyone is as eager to experiment as I am. 
 
You would think that after so long, I would learn to keep my mouth closed and just read and observe.
 
It would be hard to put a figure on just how many parts I have blown up and made glow white hot from heat. The burning smell is terrible sometimes. Not a good way of giving advice to other people, huh. 

It's the pioneers we all remember, and not those who jump on the bandwagon...
Also, we need more people to keep the Darwin Awards going.......... Those who are too clever to remain in the gene pool of humanity.
 
http://www.darwinawards.com/darwin/darwin2010.html 
 
Mar 18, 2011 at 1:38 AM Post #10 of 14

ezzieyguywuf

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Well, maybe I'll just make two separate beta22's then. I don't really own any speakers worth amping right now. I do however own some really nice Denon D2000's which don't require all that much gain (I can't turn the dial all the way up on my compass as its way too loud). I do wish to invest is some higher impedence 'phones, but I'm not sure when as I think the beta22 will be my next project, followed by a mini3 and some sort of portable dac for my laptop.
ezziey
 
Mar 18, 2011 at 6:37 AM Post #12 of 14

bcg27

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Quote:
Well, maybe I'll just make two separate beta22's then. I don't really own any speakers worth amping right now. I do however own some really nice Denon D2000's which don't require all that much gain (I can't turn the dial all the way up on my compass as its way too loud). I do wish to invest is some higher impedence 'phones, but I'm not sure when as I think the beta22 will be my next project, followed by a mini3 and some sort of portable dac for my laptop.
ezziey


AMB also has another project specifically targeted towards speakers, the B24 amp. It is a class AB amplifier that I think is capable of just under 200 watts per channel @ 8 ohms. There is also a post on the AMB forum about converting it to pure class A operation, in which case I think it was capable of somewhere around 40 watts per channel. I would like to build it some day when I have a dedicated 2 channel speaker system, but for now my HT speakers do double duty for music.
 
 
 
Mar 18, 2011 at 9:39 AM Post #13 of 14

ezzieyguywuf

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I've never heard of these HE-6's you guys speak of. I'll see what I can find out about them.
 

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