Layout for balanced beta22.. opinions please

[sachu]

I am actually planning on using this exact same (Par metal series 20 16 x 16 x 4) case for my balanced build.

According to my calculations, the nearest amplifier board would be about 4 inches from the transformer and the farthest is double that.

The transformer is 3.75 inches in diameter.

What do you guys think about this layout?

[digger945]

The "b" on board 1 isn't capitalised making your amp unbalanced.

May I ask what you used to draw the layout with?

[sachu]

Originally Posted by digger945

The "b" on board 1 isn't capitalised making your amp unbalanced.

May I ask what you used to draw the layout with?

hahha..

I used emachineshop..i will most probably use their service to get my front panel.

so what do you make of it?

[digger945]

Thanks for the link.

The first thing your gonna hear from the rest of the guys is "you should consider putting the transformers in a seperate enclosure."
After that your gonna hear "that's a lot of heat for one case."

You gotta ask yourself, if you get it all assembled and you hear the transformers, how much work, time and money is it gonna take to eliminate that.

[TimmyMac]

16x16 is huge... that's a lot of desk space if nothing else.

[sachu]

Originally Posted by digger945

Thanks for the link.

The first thing your gonna hear from the rest of the guys is "you should consider putting the transformers in a seperate enclosure."
After that your gonna hear "that's a lot of heat for one case."

You gotta ask yourself, if you get it all assembled and you hear the transformers, how much work, time and money is it gonna take to eliminate that.

Hehhe..i know. BUt what gets me is that the toroidal transformers are supposed to have least magnetic field leakage. I did not have any problems with this amplifier that i built about 3 years ago didn't have any hiss or noise problems.

It is known that the magnetic leakage coming off EI cores are some of the worst..

Most commercial and DIY builds I have seen don't use any kind of shielding with toroidal transformers as default.

The risk of there being noise is definitely there and if that be the case, i would then proceed to move the transformers to a different case.

Regarding the heat, that would be less of a problem as i will be using dual sigmas and driving for the most part headphones only. Also I live in the northwest..temperatures are pretty cool here for the most part and the Par metal case comes with ventilation on both top and bottom sides.


One more question, is it prudent to have an inrush current limiter for this build? or is the VA rating not high enough (2 160VA transformers) to justify it?

[digger945]

It's funny that you should ask that question, I just now finished reading AMB's post on another thread about the new replacement for the STEPS PS.
He was giving some facts about one of his PS's, talking about the fact that it is designed to have some "soft" start.
You may look for it, it's only a couple of threads away from this one now.

I have also tried to do a fair amount of research on this myself, coming to the conclusion that I may have to use a "slow blow" fuse to help deal with this minor problem.

Thanks again for that eMachineshop link , it's really cool.

[compuryan]

The layout looks good to me. I don't think it'll be as big as you think. 16x16 is big, for sure, but its not outrageous. Also, fully-internally shielded transformers are available to eliminate any trace of hum, but they are much more expensive than the regular transformers. Using a ground loop breaker will help with the noise too.

[digger945]

Anyone has noticed a new power supply design from Tangent's website?
top of page two.

[sachu]

Originally Posted by digger945

I have also tried to do a fair amount of research on this myself, coming to the conclusion that I may have to use a "slow blow" fuse to help deal with this minor problem.

Thanks again for that eMachineshop link , it's really cool.

Slo blow fuses don't really help with that problem..You would have to install an inrush current limiter. You can test to see if your circuit needs an in rush limiter by hooking up the toroid mains to a pwoer outlet leaving the secondaries open..if it needs a limiter then it would trip the circuit breaker.

we use emachaineshop for some of our reference prototypes..they do a very good job. Finishing is immaculate.

[digger945]

I'm sure it would be easy to calculate the surge at "turn on", however in my case (Dynamite) I am copying what others have already used.

Is the pricing for eMachineshop pretty reasonable?

[FallenAngel]

Have you considered power wiring, signal wiring and POT location? I don't care what transformers you have, you won't want Low-Z signal wires coming out of the pot to run beside the transformers and PSUs.

[sachu]

Originally Posted by FallenAngel

Have you considered power wiring, signal wiring and POT location? I don't care what transformers you have, you won't want Low-Z signal wires coming out of the pot to run beside the transformers and PSUs.

The pot would be mounted on the front panel, signal wiring would be all done using shielded cables. Power wiring would all be 16 or 18AWG cables and looking at the layout, it should all be located at the back end of the amplifier. The only wire running from the rear panel to the front would be the signal wires. Shielded wires should do well to clear up any noise issues (solved the problem as i had noise in my other amplifier with the EI cores).

[n_maher]

At a minimum I'd forgo symetry and stack the trafos on the left. Put the IEC inlet over there and keep all of your input audio signal wiring to the far right. It'll still hum, I can almost guarantee it, but maybe not enough to be annoying. In the end I question why someone would spend as much money as you are going to and be left with something pretty far from optimal.

Heat is also going to be a big issue, as already mentioned. You'll want to provide a good deal of venting both top and bottom and probably on the sides too. Be aware of all of this when you do your initial setup and decide what bias to run the output stages at.

And I don't see an amp in the link you posted sachu. I see a DAC (only thing with a toroid), speakers, a passive switch thing and picture of a collection of gear. My experience is that DAC's are sometimes less sensitive to noise because they have very little gain so if there is noise on the input you aren't likely to hear it.

[sachu]

Originally Posted by n_maher

At a minimum I'd forgo symetry and stack the trafos on the left. Put the IEC inlet over there and keep all of your input audio signal wiring to the far right. It'll still hum, I can almost guarantee it, but maybe not enough to be annoying. In the end I question why someone would spend as much money as you are going to and be left with something pretty far from optimal.

Heat is also going to be a big issue, as already mentioned. You'll want to provide a good deal of venting both top and bottom and probably on the sides too. Be aware of all of this when you do your initial setup and decide what bias to run the output stages at.

And I don't see an amp in the link you posted sachu. I see a DAC (only thing with a toroid), speakers, a passive switch thing and picture of a collection of gear. My experience is that DAC's are sometimes less sensitive to noise because they have very little gain so if there is noise on the input you aren't likely to hear it.

Thanks for the suggestions n_maher. This layout is not final of course, chasssi would be the last thing i work on but i want to keep it in mind so i can plan out the rest.
That is not a passive switch thing..

It is the passive preamp + 3 way active crossover + 7 chanel amplifer that goes with my DIY speakers (active). You just add a source to it and you are ready to go. Here is the pic of the setup . IN the middle (the top is the DVD transport, the middle is the DIY DAC, the bottom is the preamp+crossover+7 channel amp all built into one)

The two transformers are the ones at the far left, one is 350VA (drives the tweeter (LM3885) and mid amplifier (LM4780in bridged mode) channels).

The 650VA transformer drives the 2 chipamps (LM4780 in bridge mode) for each of the low channels. The 7th channels is used to drive a center channel speaker when used in a home theater setup (i think it is an OP541 chip amp)