Roll Call: Who's building, built, or thinking of building a beta22? - Page 192

Quote:

Originally Posted by bcg27 

Probably $5-600 for a bare minimum build

Yep this is better (I was allowing for a larger attenuator)

Almost ready to make my mouser order and I'm looking for a few recommendations. Mouser part numbers preferably.

First, LEDs. Which ones are people using for the boards? And what would be a good choice for a panel mounted indicator LED? For the latter, what's a good way to mount them? It seems you can buy little plastic holders for this function.

Second, switches. I need switches for three purposes:

1. Switch between transformer primaries and power entry model to select between 115 and 230V. Obviously needs rating for the higher voltage, not sure what kind of current (perhaps 80/115 = 0.7A ? But inrush is higher I suppose?). Doing two transformers so needs to be 4PDT.

2. Power switch, also between power and primary (aside: it doesn't matter if it's on the live or netural line, does it?). Same ratings I assume. Simple switch (SPST).

3. Source select switch. Sits in signal path (quality). 2x DPDT preferably, or 1x 4PDT.

Third, mounting hardware. What are people using? :)

Fourth, I'm looking at this power entry module (Mouser 631-FN282B-6-06). It's cheaper than the non-medical grade ones for some reason, OK to use?

Thanks very much

Quote:

Originally Posted by joeyjojo 

Fourth, I'm looking at this power entry module (Mouser 631-FN282B-6-06). It's cheaper than the non-medical grade ones for some reason, OK to use?

 

I used that exact module in my Buffalo DAC build. No problems at all.

For voltage selection, they make a number of power entry modules that provide this function. Digikey seems to list more of them than Mouser does, but I may have missed them. Search for :voltage selector: on Digikey, then select the power entry modules. You can probably find the same at Farnell, etc. in the UK.

Excellent, thanks very much. I'm now thinking this one: 592-PM0SXSSXB, which has connections for dual primary transformers, standard filter, 10A rating and shielding. It's ideal.

So, still to figure out are the LEDs, individual power switches (2xSPST for dual s22s), source selection switch (2x DPDT), and mounting hardware.

Power switch: 540-CRE22F2PBBNE ? What the hell is quick connect? As opposed to soldering...

Also, how about this as a source select 633-GW22LHP ? It takes .100 molex by the look of it, which is nice.

Edit: damn the power switch is minimum order size 810 :/

LED's are extremely unimportant. You don't even need them actually. Any color is fine, just calculate the appropriate resistor you need from the led forward voltage drop and your power supply rails and you are done. 

Quick connect means you use things like this: http://www.mcmaster.com/#lug-terminals/=fyouvv

Switches are one of the things that makes your build unique. Pick something with an appropriate rating that you like the look and form factor of. That's about all there is to it. 

Its quite an expensive amp, is it so much better than the M3?

Yes, IMHO. 

Quote:

Originally Posted by K3cT 

Yes, IMHO. 

+1 on that :)

The law of diminishing returns sets in, I threw everything at mine, I don't think I could have spent more on the build and I love it, it is great and wouldn't replace it, if you can afford to do it right, do it.... :]

However, it started a chain reaction, previously I had M3 and EMU0404, once at the B22 I had to buy new DAC, then new 'phones and a lot of tweaks until I was as happy. It was a bit like a last 15% thing, M3 was 85% and the B22 brought the last 15% (for a lot of money)

I suppose what I am saying is that don't expect miracles, nor it to be your last purchase and given my experience with an all Blackgate N'd, PRP, balanced, Goldpoint attenuated monster I can't imagine a two board B22 is miles ahead of an M3. As always, the more transparent the equipment the worse the music gets, I still enjoy the M3 at times for the warmth :)

Quote:

Originally Posted by amb 

If you're using a source that is "too hot", then you might want to add an input attenuator at the amp. Here is a schematic of a switchable attenuator. It is drawn for an unbalanced (2 or 3 channel) amp, for a 4-channel balanced amp you'll need to double everything for the negative signal, and use either a 4PDT switch, or two DPDT switches.



If you use the same value for all the resistors, then the attenuator will drop the effective gain of the amp by one half (-6dB). A good value to use is anywhere from 10K to 47K.
 

Ti, what's this? With the switch one way it shorts the resistor and sees the signal, with the switch the other way it sees ground...?

With the switch in the position as shown in the figure, the input goes directly to the pot (no attenuation). With the switch flipped, input goes through Ra and then to the pot with Rb in parallel to the pot... i.e., a voltage divider. Attenuated.

In other words...it's a "mute" switch...

Thanks Pars, I was being thick.

Reading through these threads has convinced me to build a Beta 22. I need to let my wallet recover from my latest headphone binge (MiniMAX, GrubDAC, and Denon D5000 headphones, all in the span of a month.) I'm probably going to do the 3 board active ground, with separate enclosures for the amp and power supply. (I actually have a Sigma 22 kit on order to replace a blown power supply on one of my other amps, so that will be good practice.)

I started sketching out some case ideas. I have access to a pretty insane (in a good way) machine shop at work, which will make the case work easier. I'll probably have to wait until Fall to order the board sets, but I'm going to get the BOM started and get some parts together for the case and wiring. In the mean time I plan to do a lot of reading (I'm about 1/2 way through this thread, and have spent some time at Headwize as well.