[dude_500]

Quote:

Originally Posted by UKToecutter /img/forum/go_quote.gif Oh, I forgot to ask. Did anybody use the ε27 board to mount their pot? Is it worth doing?

I used it and it works very well, I think it's a great idea, especially if you need to do maintenance on it in the future where removing solder joints right on the pins could cause damage.

I have since ordered the combo again for another build of a different amp... that will be my volume knob of choice unless I find something superior in the same price range.

 

[oneplustwo]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Since the LED is powered off the rails, and since you have no rail voltage, might not be anything wrong there. The first thing I would do is go through every component, making sure it is the right part (particularly transistors) and that they are oriented properly. If that is fine, then with a schematic handy as well as the operating points, you probably want to start at the input and work towards the output until you find something that isn't right. Double check your transformer wiring as well.

Thanks for the guidance Pars. I checked the trafo wiring and part orientation. Might be difficult to check that the parts are actually correct... dang things are so hard to read, but I'll give it a go.

 

[UKToecutter]

Quote:

Originally Posted by dude_500 /img/forum/go_quote.gif I used it and it works very well, I think it's a great idea, especially if you need to do maintenance on it in the future where removing solder joints right on the pins could cause damage. I have since ordered the combo again for another build of a different amp... that will be my volume knob of choice unless I find something superior in the same price range.

Thanks dude_500.
I'll add that to my next order

 

[UKToecutter]

Does anyone know who manufactures that braided cable sheething that people are using in their builds. Makes a real nice finish.

Look at http://www.head-fi.org/forums/6291774-post2106.html

2nd picture down shows what I mean. On the right hand side.......

Very pretty

 

[Possede]

Hello UKToecutter, thanks for the kind comments. I got the braid from SMCS-UK Commonwealth Stamps on eBay. Very cheap and fast delivery. It's either the 3mm or 6mm.

 

[UKToecutter]

Thanks Possédé

I'm on it

 

[jlefley]

I'm starting to gather parts for a 4 ch balanced beta22/dual sigma 22 build and I'm wondering if there would be any noticeable effect on SQ or anything else if I used one of the s22 boards to power a Joshua Tree attenuator with two relays boards. I realize that the regulator on the JT relay driver board will get pretty hot due to the larger input voltage but apart from that would the ~400ma that the JT draws have any other noticeable effects on the amp?

 

[IPodPJ]

You could get a 3rd trafo and a cheaper low noise power supply.

 

[jlefley]

Quote:

Originally Posted by IPodPJ /img/forum/go_quote.gif You could get a 3rd trafo and a cheaper low noise power supply.

Considering the simple power supply that the JT relay driver board has integrated, it seems like it doesn't really an additional power supply with good regulation or low noise properties to supply the onboard regulator. I think it would be redundant to put an additional power supply in the box with the sigmas just to provide regulated power to the 5v regulator on the JT board located in the box containing the b22s. I'm just thinking that it would be an easy solution to draw power from one of the s22 that will be in place unless it will have any sort of adverse affects.

 

[IPodPJ]

Well I'm adding a third to mine to keep the audio channels completely free of any possible noise from the LEDs, relays, or motor drive on the attenuator. Just a suggestion. I know it isn't common, and I'm not sure if anyone's ever done it on their B22.

 

[linuxworks]

it would seem wise, if you can afford the space/etc, to have a separate power supply for digital control things. I'm going that way in my arduino builds and if you do have a bank of non-latching relays, you may want to have a pre/post setup for that. meaning, you can have preregulated voltage (before the 'logic' 5v regulator section) going to relays and then post-reg for the things that really need something a lot closer to 5v.

many relays come in various voltages and so you could select your relays in the 'bank' to be a few volts higher than the 5v logic section needs and then feed the relays off of this pre-reg voltage.

not the only way, but a nice stingy way to do it

same applies to motor-pots. some won't take more than 5v but I think I've had some that ran faster at 9v and didn't seem unhappy about it

so you could do the pre/post thing for motor pots, too. just be sure the pot can *take* more than 5v.

I would not have control circuits going too close to audio paths and that also does include deriving b+ from the audio power supply rails. I do like the idea of a separate reg and trafo chain and if you get a custom trafo build (like from sumr) you can request another winding just for the digital control stuff. I was going to do that, myself, for an amp+controller project. if you can get an extra winding for almost-free (custom trafo with 1 more winding) do it! else you have to find space for a small 7v (etc) trafo for the 5v digital stuff.

 

[linuxworks]

Quote:

Originally Posted by UKToecutter /img/forum/go_quote.gif Does anyone know who manufactures that braided cable sheething that people are using in their builds. Makes a real nice finish.

is that tech-flex that you're talking about? the blue stuff that I use, for example:

I used some blue for some runs and some black for the b22 amp boards to the motherboard. red shrink tubing just cause that's what I had on hand at the time

is this what you're referring to? you can buy it in many colors and use whatever color heat-shrink you want. you can pick a theme and run power with one color and line-in with another and line-out with another! or not

its not braid and not shielded, just a plastic expanding web-like thing that collects wires into tight groupings. and when you cut this stuff to length it frays and so you *have* to do the heatshrink tubing thing or it will look really unfinished and sloppy.

 

[jlefley]

Yeah the more I think about it and based on the replies I'll probably just get an additional transformer and put together either a TREAD or sigma25 to provide the 5v.

 

[Beefy]

Quote:

Originally Posted by jlefley /img/forum/go_quote.gif Yeah the more I think about it and based on the replies I'll probably just get an additional transformer and put together either a TREAD or sigma25 to provide the 5v.

The JT controller has an onboard voltage rectifier and voltage regulator. Why do you feel the need to feed it DC?

 

[linuxworks]

just a thought: but do you want to design your 'infrastructure' (ps and wiring) based on some products or make it more generic? the JT has onboard reg and stuff but others may not. if you plan for it in the infrastructure you have more upgrade options available to you later on. since the chassis is a big part of the cost, it might make sense to plan for extra PS lines 'just in case'.

heck, I'd want an extra 5 and an extra 12/-12 or something like that in case I need extra audio rails