[gates_2]

oh- i need to change my order with you then Ti ....:-/

 

[swt61]

Well I got back from a 6 week out of town job today, and my β22 was waiting for me, along with my new Opus DAC .

This β22 is a four channel balanced unit with dual σ22 power supplies in a seperate chassis. It also has speaker binding posts installed for efficient speakers. The stepper is Twisted Pear Audio's Joshua Tree logarythmic stepped attenuator, and it's fully programmable.

No real impressions until I've had a few days to spend with it, but I have a big, stupid grin on my face that won't go away.

These were built by fierce_freak, and his workmanship is incredible!

 

[utilisateur]

I'm planning on building a β22 aswell ; I was just having a look at the heatsinking for use as a speaker amp and tried to calculate the needs
BUT assuming 3/4 of max output current i get an output power of 13,5W with 30V supply , with a minimum load of 6 Ω and a maximum ambient temperature of 40°C amb's equation shows the need for a thermal resistance way below 2°C/W
to stay below 100° , which would be impossible with the mosfets thermal resistance !?

I'd be pleased to get some help/hints here

here the equation

TIA!

Quote:

Originally Posted by swt61 Well I got back from a 6 week out of town job today, and my β22 was waiting for me, along with my new Opus DAC . This β22 is a four channel balanced unit with dual σ22 power supplies in a seperate chassis. It also has speaker binding posts installed for efficient speakers. The stepper is Twisted Pear Audio's Joshua Tree logarythmic stepped attenuator, and it's fully programmable. No real impressions until I've had a few days to spend with it, but I have a big, stupid grin on my face that won't go away.

sweet

looking forward to further impressions

 

[amb]

You should assume a much lower average output power (e.g., 1/10 of maximum) for the purpose of this calculation because music is not sine waves. You'll get much more reasonable heatsink demands. See a similar discussion in the β22 thread at headwize starting at post #502 and a few posts onwards.

 

[utilisateur]

Aah thanks alot amb thats wonderful

so 1/10 would be a safe assumption?
sweet thats 5°C/W alot more practical
i have to add up the heat dissipation of every transistor that attaches to one heatsink though eh?

compliments for your work and helpfulness

regards

EDIT. thank you for the specific link , your answers over there help alot

 

[amb]

Quote:

Originally Posted by utilisateur /img/forum/go_quote.gif so 1/10 would be a safe assumption? sweet thats 5°C/W alot more practical

Yes, it's safe as long as you don't use the amp to run a disco.

Quote:

i have to add up the heat dissipation of every transistor that attaches to one heatsink though eh?

Makes sense, doesn't it?

 

[swt61]

Quote:

Originally Posted by amb /img/forum/go_quote.gif Yes, it's safe as long as you don't use the amp to run a disco.

Crap! Well I guess I'll put that mirrored ball in the for sale forum.

 

[el_matt0]

hey all, ive got a question about what exact wiring scheme i should use for my beta22 setup. i plan to have one set of balanced outputs, 2 single ended 1/4 outputs, and speaker outputs (not all for simultaneous use hehe). i know there are several diagrams on the AMB site that are very close to this, but the one thing that im unsure of is, i dont want to necessarily have any single ended inputs, id be much happier with just one set of balanced inputs. can i make this work is basically what im asking

? any help or advice = greatly appreciated as always. thanks all

 

[n_maher]

Matt,

Yes, it's perfectly possible to do this. How? I'm going to let you stew on that one a bit and see if you can't figure it out. Ask yourself, what is a balanced signal really and how is it different from a single ended signal? And the answer is in amb's beta22 web pages.

 

[swt61]

And I have only balanced inputs on mine, with a SE 1/4" output, as well as balanced and speaker outputs.

 

[el_matt0]

do i just wire them all up together? ie, for the speaker outputs i just run L+, L-, R+, R- each to a binding post right? i connect the XLR balanced outputs as before, but with grounds as shown in many of the diagrams on AMBs site. and then for the SE outputs, do i just run my L+ to the L signal, the R+ to the right signal, and what for the ground, both L- and R-? do these outputs not connect to the ground pins of the pot?

 

[strangedaze39]

Wow do I need one of these. Very cool guys.

 

[naamanf]

Quote:

Originally Posted by el_matt0 /img/forum/go_quote.gif do i just wire them all up together? ie, for the speaker outputs i just run L+, L-, R+, R- each to a binding post right? i connect the XLR balanced outputs as before, but with grounds as shown in many of the diagrams on AMBs site. and then for the SE outputs, do i just run my L+ to the L signal, the R+ to the right signal, and what for the ground, both L- and R-? do these outputs not connect to the ground pins of the pot?

Look at the last picture in the "Wiring & Ground" section on the B22 site. Just like that. With the SE jack wire the ground to PSU ground.

Edited.

 

[n_maher]

It would also be wise to peruse the "Other Options" section of the site.

 

[el_matt0]

thanks guys i think ill manage to figure it out, ill be sure to have more questions if not!

on a bit of a different note, i figure this is the appropriate place to place the question, what speakers would you guys say pair best with something like the b22? i think im looking for a moderately affordable (definitely <$1000) pair of bookshelves (as bookshelves are pretty much all it is intended to drive right?). any advice would be appreciated. for those of you that do already use a b22 for speakers, do you just use speakers with woofers in em, or do you use a separate sub (if you do use a separate sub how do u hook it up since i believe ive only seen most ppl incororate 2 pairs of speaker outputs from the b22)