I don't know which grounds connect together in my new amp

[Menryk]

Which of grounds (see numbers) I should connect together ?

Where is the best place to connect ?

[PRR]

Welcome.

It would really be better to steal a *complete* ground-plan from a known-good amp.

[jjasilli]

This is a complex topic with differences of opinion.  Actual physical ground connections are not always clear from schematics & layout diagrams.  Doug Hoffman who sponsors this Forum has proven grounding scheme info on the Library Pages of this Forum.  Also checkout sites on google such as the Valve Wizard and Aiken Amps.

[EL34]

I moved this, it was in the wrong board

[Menryk]

Hi PRR,
thank you very much for your ideas.
It looks interesting and good I hope it will work well.

My amp is prototype.
I tried to connect difference parts from difference equipment.
During my work I correct some problems but sound (clean) is good and over-drive not bad.
I'ts not my first amplifier - at the end of 60-ties I made Orange Mk2 without 2xEL34 (half power).
I used it to this days but it has too much power so I decided to build small but with effects.
I want to add digital reverb.

Of course I want to do the best I can so I try to correct some faults.
Because my amp is prototype I can't use some example.
What I see at the schematics, doesn't explain some details, like grounds.
I saw Peavey 20 and 30 and they have 3 or 4 grounds and between them they use resistors 47ohm.

Here are my questions.
1. What is the purpose for these resistors 47ohm in Peavey Classis 30 or 20?

2. My chassis and box are from steel.
On your picture you connect in-put with chassis and ground="0" from the cable with chassis too.
Am I right?

3. 2x100ohm with AC 6.3V for EL84 will be good?

4. In fact ground DC 6.3 I have 2x150ohm and this is ground 8 not minus.
And PLUS and MINUS are connect to the ECC83 - without ground.
Should I change this?

Please, look at my correction picture.

[PRR]

Does it play well?

[Menryk]

Hi PRR.

Now I'm in the proces to changing few things.
First time I had 2 grounds like in Peavey 20.
But I'm not convince that is the best.
I don't understand Peavey idea for grounds (resistors 47ohm).
Clean sound was good or very good.
Crunch not bad too.
When I will finish correct grounds (mechanical work) I will start to resolve problem with level of signal in LINE-output after preamp and sound corrector
and then I will add digital reverb.


Because it is SE class A so there is some law brum, very law brum (I hear it only when I put my ear to speaker)
and
when I change all potentiometers on full there was some hum.


Could you answer for my 1 and 2 question from last message, PLEASE?

And I add next 2 questions (number 3 and 4 from last message) about fillaments for ECC83 and EL84.

Which is better A or B
and
Which is better C or D

greetings
Menryk

[Menryk]

Hi jjasilli.

Exactly,
I agree with you because Actual physical ground connections are not always clear from schematics & layout diagrams. .

It is reason that I sent my question to Forum.
Of course I could connect all to 1 wire but I wrote some interesting artikles about connection elements and then I started to think -
May I change something to do better and maybe sound will be better (who knows).

And in the beginning I've heard cicada' effects. And then I started to correct filament chargers.

I have only few multimeters and I can't check what is happen inside my amplifier (like high frequencies).
You know, this is only hobby for my private use.

greetings
Menryk

[jjasilli]

It's not clear you have a ground issue.  A ground-noise issue will sound like a steady hum.  You are describing a repetitive chirping or pulsing.  Maybe this is a different issue:  motorboating???

Meanwhile, the device (amp) amp will function no matter where ground connections are made.  If there's no noise there's no problem.  Re grounding technique, noise can arise in 2 ways: power supply noise (60 cycle hum) mixes into signal; or ground loops.  (Hum & noise can arise in other ways, but we're focusing on grounding schemes.)  The Gremlin factor:  If two amps are built the same way, one may hum while the other doesn't!  Hence better practice is to follow an established grounding scheme.

BTW:  Your schematic is incomplete.  Is there a tremolo circuit?

[sluckey]

I'd like to see a complete schematic for this amp.

[Menryk]

Thanks jjasilli,

I am conscious about 50 cycle hum and ground loops.
First I asked because of these two reason.

Because of 50 cycle hum I divided capacitiors 2x50uF and 2x20uF and on the schematic PRR did almost all what I supposed.
Because of ground loops I tried confirm my thinking that I use only 1 point to ground down every block and cable.

I have no tremolo.
I plan to add digital reverb at least.

Normally I don't hear anything.
When all is on full then small noise-hum(shhhh).

But when I get into input, cable from guitar with all potentiometer on full I've heard noise like tz, tz, tz, tz - every second.
Do you know insects like cicada? Their voice is like tz, tz, tz or something like that.
And then I change charger for DC6.3 for ECC83.
I added 10000uF, 2x150ohm, 1x1ohm and 6800uF directly to tubes.

Next time I send schematic with more important details and generall arange of details.
Now only power supply.

Menryk
 

[Menryk]

Hi sluckey,

OK, I will send complete schematic.

Menryk

[Menryk]

It is assembly schematic.
With all potentiometers and switches and in-put socket and out-put socket (speakers).
Switch without notice turn-on over-drive.
At the schematic all function works.
I mean over-drive, Treble Boost and Bass Boost
The orange lines mean boards.
Reverb is disconected so points H and K are free.
Instead resistor 47ohm is wire

I still build this amp.
After resolving ground problem I will work with reverb.

[PRR]

> noise like tz, tz, tz, tz - every second. Do you know insects like cicada?

Cell-phone or similar. They "ping" the cell tower every second so it knows they are available.

Also Wi-Fi, Blu-Tooth, and other radio data.

Possibly airport radar.

[Menryk]

I've red that sounds like -tz -tz depends on semiconductors in chargers which are too slow ???
In fact they wrote about high-gain circuits where is very important no-hum charging filament of 1st tube ???

So maybe you (PRR) are right with some electronic sources.
I need observe carefully.

ANYONE could answer for my question from

reply #4 question 1 and 2
and
from reply #6, please?

Menryk

[ALBATROS1234]

I am a newbie but my experience is that where and how you ground everything makes a huge difference. Being an electrician we ground everything everywhere the more the better. In audio I found out the hard way this create all kinds of funky noises squeals pops and chirps. The last 2 amps I left all my grounds long until everything else was wired and the amp was working then using alligator clip leads experimented until there was no funky noises or excessive him. As a note I have only done my own circuits which were based on a combination of known schematics with small tweaks so I could not use the ground patter. From another amp.

[Menryk]

Thanks Albatros,

of course I agree - that is very important.

You know before I started to build amp I thought where I should put my important details like transformers, potentiometers, high voltage, low voltage and filament wires and how I need their arrange (spinal of transformers).
And try arrange where should be connections between wires.

This amp is good althought still I correct some things.
But my Orange Mk2 (60W) I soldered 3 times from the beginning.
And at the end I used printed board like in this small (5W) amp too.

Before that my amp sounds not bad BUT I want to do the best what I can.
So I will correct some details. And now I still build it.
And because it is prototype I can't use example of any amps.
I try to use basics principles.

So PRR drawed schematic of connections of my 5W amp and it is I expected, exept 3 points.
See Reply#1
So I'm glad for help. And I want to apply his ideas.

[EL34]

Here's how I ground stuff and never have any issues
http://el34world.com/charts/grounds.htm

[Colas LeGrippa]

It is so simple !
All of my builds: no hum, no hiss, no parasitic oscillation.


Preamp, but not the PI :


ALL the grounds to the ground of the input jack carefully installed for a perfect contact with the chassis, this includes all the preamp tubes but the PI.


Power section: (including the PI )


All the grounds from filtering caps, cathodes of power tubes, screen reference resistors, heater reference and so on, at a place near the filtering caps.


110V supply:


one and only one ground (not shared with nothing else) to the chassis, (close to the 110v cable entry) previously scraped to bare metal with a star locknut,  tightened to the bone !!!!


This looks like what PRR suggests and assures you of a stable amp. It is important though to ground the shielded signal cables ONLY AT THE INPUT JACK SIDE. Anyway you don't have no choice since there is no other preamp ground that you can choose, the other one being on the power amp side. For parasitic oscillation (to avoid, I should specify... ) it is important to add: grid stoppers on power tubes, resistor bypass caps in the case of a cathode bias amp, in a class A amplifier, absolutely important.


Colas

[Menryk]

Thanks Colas LeGrippa,

I applied suggestons of PRR.
Still I want to correct what I could change.
Mechanically I have what I have.

I attach view of my amp with explanations.