Wayne's BA 2018 linestage

[Russellc]

With a little card board box over the boards it is a little more stable, but maybe up to 2.5 or 3.0 mv......guess its time to add a pair of RCAs on the input and outputs and hear this thing!

Russellc

 

[6L6]

Maybe I just need a comfort level adjustment! Nightmares of speaker frying.

Let’s say for a second you have 50mV DC on your speakers.

0.050v/8ohm = 0.0062A, or 0.00031W that your speakers coils need to deal with.

 

[Russellc]

Ok, attaching RCA plugs. Have selector and power switch coming from tubecad. Looks like Diyaudio store doesnt have the Galaxy 388 width case....nuts. Used two of those cases for preamps, perfect size without going full width.

Next size down from full size is 9 inches, little too small.
Russellc

 

[Mod Man]

Received a Galaxy 330 X 280 yesterday. A little large in my opinion but pleanty of room for Wayne’s linestage and TubeCad power supply .

 

[wdecho]

With a little card board box over the boards it is a little more stable, but maybe up to 2.5 or 3.0 mv......guess its time to add a pair of RCAs on the input and outputs and hear this thing!

Russellc

Think what a millivolt is, 1,000th of a volt. Waving you hand close to it can make a change when dealing with millivolts. DC on the output of an amplifier just moves the voice coil a certain amount. You get a turn on turn, off thump but as long as the voice coil in not impeded for full movement it is not that big a deal. With my big efficient horns 50mv DC on output is not really detectable. I have built some gainclones in the past with close to 100mv DC on the output without any problems. Button it up and enjoy.

 

[Russellc]

Let’s say for a second you have 50mV DC on your speakers.

0.050v/8ohm = 0.0062A, or 0.00031W that your speakers coils need to deal with.

Oh, I was under impression that power amp would somehow "amplify" the DC to a higher level. I probably shouldn't measure DC on my other preamps for best sleep. I guess speakers can only see what is at output of power amp, if all well there nothing to worry about.

Russellc

 

[Russellc]

With a little card board box over the boards it is a little more stable, but maybe up to 2.5 or 3.0 mv......guess its time to add a pair of RCAs on the input and outputs and hear this thing!

Russellc[/QUOTE

Waving you hand close to it can make a change when dealing with millivolts.

Yes, you should have seen me freaking out trying to set DC off set on my first BA3 preamp....while sitting under a ceiling fan...

Russellc

 

[labjr]

Maybe you can use your preamp as a theramin?

 

[Russellc]

Received a Galaxy 330 X 280 yesterday. A little large in my opinion but pleanty of room for Wayne’s linestage and TubeCad power supply .

I really liked the size like 6L6 used in his BA3 as preamp build thread. Right at 12 inches wide, I don't see it in the store anymore....is yours 330 wide? If so I must have over looked it.

Russellc

 

[Dennis Hui]

Might be this one:

Galaxy 2U w/Steel Covers – diyAudio Store

It looks like a good size.

Dennis

 

[wdecho]

Oh, I was under impression that power amp would somehow "amplify" the DC to a higher level. I probably shouldn't measure DC on my other preamps for best sleep. I guess speakers can only see what is at output of power amp, if all well there nothing to worry about.

Russellc

Amplifiers do not amplify DC. Of course you want as little DC on the output of a linestage as possible but a tiny bit ,a few millivolts, is not going to hurt a SS amplifier. Another case with a tube amplifier. If you have what you consider too much DC on the output of a linestage just put a good cap on the output.

 

[Russellc]

Might be this one:

Galaxy 2U w/Steel Covers – diyAudio Store

It looks like a good size.

Dennis

Yup, but I will need at least 3U to clear heat sinks on power supply. Appears to be the right width.

Russellc

 

[Mark Johnson]

I'm using horizontal mount heatsinks on one of my projects, and am finding it easy to fit a PCB that dissipates ~ 10 watts, into a ventilated chassis whose height is only 1U.

Here's one of the heatsinks I'm using, Mouser part # 532-551002B00G .

 

[Russellc]

This is the tubecad power supply that 6l6 recommended. Like a ding ding, I specified the higher heatsink, which I don't even feel getting warm. I will check out the part number you show.

Thanks for the tip,

Russellc

 

[Mod Man]

The inside height of the 2U is a little over 3". Should fit you regulator.
I measured the total current for the line stage and it's 70mA. I don't think you need a heat sink at that level.

 

[Russellc]

I don't think you need a heat sink at that level.

That's what I meant by stating it doesn't get warm.....its what I have, not need. Yes, I see height of case, sink is 2.5", then there are legs...I have some shorter ones if necessary. I like lots of room in cases, more air, easier to set, adjust, repair, modify etc. No biggie. I sent an email to them and can no doubt work it out. If not, it will be used in some other of the plethora of First Watt projects I have going on.

Russellc

 

[Russellc]

Already got email canceling...now to reorder!

Russellc

 

[Dudeisms]

Dumb newbie question... got a recommendation for a nice IEC power inlet? Filtering necessary or helpful? And or fuse holder

Also which resistors are the output resistors? I need to use 27k or whatever was recommended in thread earlier to lower the gain. Thanks in advance

 

[6L6]

The choice of IEC is largely a space issue - if you have lots of real estate for it to intrude into, I'd go whole hog and get one with switch, fuse, and filter. They have no wiring required, you just attach your transformer and chassis to the L, N, and Earth tabs.

 

[Dudeisms]

Ok I will get one of those... any specific specs I am looking for?... I see lots of choices. I don’t have a case yet, but I am sure I will have enough real estate.... because I already need it for a 2nd toroidal and extra pcbs for the attenuation and selector