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    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Internal placing of components

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#23
mosfetmaster said:
Obviously I'm not obliged to mount components on PCBs but it seems to be the best way for a beginner; mounting components on chassis and wiring them manually appears to be a much more troublesome way to proceed.
Click to expand...

I like PCBs too. You draw the circuit, make the PCB, place the components, it works. There can be problems with tubes, however, that you don't get with solid state.

Tubes, valves, run hot. Many resistors in tube amps run hot. It is not uncommon to melt the solder on a PCB. You cannot twist heater traces on a PCB, better to wire these. Components on a turret board have air circulating around them, you can do this on a PCB, but first you must know that you need to do it.

Good luck.

w
 
#24
mosfetmaster said:
So, I begin to think that lodging power supply unit in a case apart would be the best choice...
Click to expand...

You can fit it on the same chassis. This is what I would do!

Decide which side you want the mains switch to be on at the front. This gives the side for the power supply!

Install the mains switch in the chasss and put a filtered mains socket on the same side at the back.

Now mount your power Tx towards the front on the same side as the power switch leave some room to put an inrush current suppressor between the switch and the power Tx primary to stop inrush current in the torroid.

Now run your mains with a twisted pair through a ferrite bead along the side of the case to the switch.

The next thing is to mount the Audio input on the other side at the back of the case . You can put relay switching for inputs if you want to. Then run your Audio from the back along the side of the case with screened cables to your volume control.

The centre of the case is now free to mount your tubes etc.

Put any power supply caps and regulators between the power Tx and the mains filter at the back of the case on the same side as the power switch.

You can now mount your output transformers on the top at the back of the case and make them look nice. Leave your output connections in the middle at the back.

You should be able to figure the rest out from here!🙂

Regards
M. Gregg
 
#25
M. Gregg,

Wow! Thanks for the layout placement. I'm a nuby and just starting my first amp. I was thinking about running the main ac up the middle and branching off left and right for each channel ending up with the opt's right by the speaker terminals. Sorta keeps everything symmetrical if you know what I mean. Will this work OK?

Regards,

John
 
#26
jea said:
M. Gregg,

Wow! Thanks for the layout placement. I'm a nuby and just starting my first amp. I was thinking about running the main ac up the middle and branching off left and right for each channel ending up with the opt's right by the speaker terminals. Sorta keeps everything symmetrical if you know what I mean. Will this work OK?

Regards,

John
Click to expand...

You are best off keeping the AC line stuck in the corner of the chassis. Twist it tightly. I think puting the AC and rectifier dead center is the worst place as it exactly minimises the distance from the AC to al other parts of the amp.

I'm thinking that in my next amp I will place all the AC wire, recifier and first filter cap inside a closed steel box under and at the and of the main chassis.

Then I thought I'd build a wood cabinet for the amp and put the DC suply in it's own cassis, maybe mounted upside down the to top of the cabinet. Most DIY'rs don'r bother with caninets for hifi amps but I think they allow a way to get the power supply far from the other stuff. I think I wrote above how the inverse square law helps.
 
#27
Well, guys,

Thanks to everyone for the opinions and the suggestions: I have now many points to refelect...I'll let you know.🙂

But now comes out a new issue: my amp would be "integrated": I have a stereo preamp and two push pull amplifiers with EL34 (one for channel); Now, I have only a transformer with 220 VAC on secondary, so 310 VDC that is ok for the preamp, but too low for EL34;
How could I resolve this?
Should I use a second anodic transformer with proper voltage (260-300 VAC) to supply EL34 anodes?
Could I elevate 310 VDC in some way such as duplicating cells?

Thanks 🙂
 
#29
John,

If you are mounting the power Tx on top of the chassis, you could move it to the back on the same side to improve the looks if you prefer looks to functionality, the chassis will shield the underside. However the layout in the picture will minimise any pickup. I also notice that the output Tx is a bit close to the input phono connections. I would move it over a fraction.


Regards
M. Gregg
 
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#31
M Gregg,

Yes the power trans will be on top. What about moving the speaker terminals to the right and mounting the input connections to the left of the speaker terminals. Any problem with that? Any thought about the minimium distance between the speaker treminals and the speaker terminals to the input connections?

Regards,

John
 
#33
John,

Do not put your "audio in" between the power supply and the output.
You have to understand that the higher the Voltage and current on any part of the equipment it will produce higher magnetic fields.

AC voltage is a major problem. So heaters/ mains cables output Tx all have changing current. DC is a problem also if it is changing in values.

So in order of Noise you have Mains power and all related equipment "cables, Tx,"
Then you have output power equipment cables and Tx.

The low voltage input is sensitive to any magnetic fields or high voltage/high current parts. You must keep any gain stages away from all these sources of power! If you ignore this you will have problems. If you do not star earth all your equipment (have one connection that all earths go to), you will have differences in potential between parts in your equipment. This will cause current to flow through your ground system.

If a magnetic field around equipment comes in contact with a conductor it will induce a current. This will be amplified and you will get hum and distortion!

The ultimate goal is to stop any fields from power or output from interfearing with your low level signals. The higher the voltage or current through a cable "or pcb track" the greater the distance the magnetic field expands from that cable.

This is basic transformer/ generator theory! However you could just try a layout and hope for the best. You might be lucky.

Regards
M. Gregg
 
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#36
John,

Also please remember you are working with high voltage. Please put a discharge resistor across your HT caps a 1M ohm at 2w-3W will discharge your HT over a period. Remember always test with a multimeter before you touch anything even if it has been off for some time!
 
#37
Wavebourn said:
Have you seen this thread? http://www.diyaudio.com/forums/tubes-valves/71300-photo-gallery.html
Click to expand...

Well, really I meant something else;🙂
I already have a precise idea of what I want and already have the proper case ready for the mounting according with, and THIS is my real limitation in placing components.
I already choosen a "visual" layout for tubes, already have the case top panel holed, so the challenge is to make the best job starting from that.
If I'm here asking for opinions and suggestion is just to try a bit harder than a square box, do you understand?...
I would make a good level job.

Anyway as already said (but maybe you missed the post) at the moment I have enough "materials" to think about, so I'll reflect and I'll decide.

In add, I reported a new issue in a previous post, I propose it again here:

I have a stereo preamp and two push pull amplifiers with EL34 to supply; Now, talking about anodic voltage, I have only a transformer with 220 VAC on secondary, so 310 VDC that is ok for the preamp, but too low for EL34s;
How could I resolve this?

1- Using a second anodic transformer with proper voltage (260-300 VAC) to supply only EL34s anodes apart.

2- elevating 310 VDC in some way such as duplicating cells, getting the proper voltage.

3- Getting working EL34s with 310 VDC.

What would be your suggestion about?

Thanks 🙂
 
#40
mosfetmaster said:
I have a stereo preamp and two push pull amplifiers with EL34 to supply; Now, talking about anodic voltage, I have only a transformer with 220 VAC on secondary, so 310 VDC that is ok for the preamp, but too low for EL34s;
How could I resolve this?

1- Using a second anodic transformer with proper voltage (260-300 VAC) to supply only EL34s anodes apart.

2- elevating 310 VDC in some way such as duplicating cells, getting the proper voltage.

3- Getting working EL34s with 310 VDC.

What would be your suggestion about?

Thanks 🙂
Click to expand...

Here you go: http://www.diyaudio.com/forums/tubes-valves/38278-line-tube-learning-newbies.html
 
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