Hello everyone .. I want to make an power amplifier for guitar which is up to 20 watts. to have only volume (ie to be clean). basically to have for pre-amplification 1 or 2 ecc83 - ecc81 and for output to have 2 el84 (push pull). the rectifier will be made of diodes so we are talking about class AB ,, I just do not find any schematic on the internet.. somebody help me .
Welcome to the Tubes / Valves Threads of diyAudio Forum.
This is most often tube Hi Fi amps, sometimes guitar amps.
Did you know there is an Instruments & Amps portion of diyAudio Forum?
They do guitar tube amps there.
By the way, getting 20 Watts out of a pair of EL84 amplifiers is normally only possible on a guitar amplifier that is clipping.
There is less possibility of getting 20 clean watts from a pair of EL84 out of a Hi Fi amp.
Either the signal will be distorted (clipping), not Hi Fi; or the design of the amplifier that squeezes that much undistorted power out, will be exceeding the maximum dissipation ratings of the EL84 tubes.
This is most often tube Hi Fi amps, sometimes guitar amps.
Did you know there is an Instruments & Amps portion of diyAudio Forum?
They do guitar tube amps there.
By the way, getting 20 Watts out of a pair of EL84 amplifiers is normally only possible on a guitar amplifier that is clipping.
There is less possibility of getting 20 clean watts from a pair of EL84 out of a Hi Fi amp.
Either the signal will be distorted (clipping), not Hi Fi; or the design of the amplifier that squeezes that much undistorted power out, will be exceeding the maximum dissipation ratings of the EL84 tubes.
More like 15W is possible, check the guitar amplifier section.
See if you can find an old Dynaco SCA-35 or ST-35 to rebuild.
The three transformers in them alone are over $300 new.
See if you can find an old Dynaco SCA-35 or ST-35 to rebuild.
The three transformers in them alone are over $300 new.
15w with two EL84. Google Vox AC15 or an early Marshall that uses that tbe. I cannot remember the model. There are tons of schematics but not so much here at diyaudio.
rayma,
Many on this forum can design a push pull EL84 guitar amplifier that will deliver 20 Watts at heavy clipping (like a heavy metal guitar amplifier).
10 Watts rms into 8 Ohms is 8.94Vrms, and that is 12.65V peak.
When the amplifier clips at 12.65V peak, we have 20 Watts rms.
When a sine wave peak voltage, and a square wave peak voltage are equal, the square wave power is 2X the sine wave power.
No, it is not Hi Fi, it is heavy metal. Many do not like that sound, others do.
Many on this forum can design a push pull EL84 guitar amplifier that will deliver 20 Watts at heavy clipping (like a heavy metal guitar amplifier).
10 Watts rms into 8 Ohms is 8.94Vrms, and that is 12.65V peak.
When the amplifier clips at 12.65V peak, we have 20 Watts rms.
When a sine wave peak voltage, and a square wave peak voltage are equal, the square wave power is 2X the sine wave power.
No, it is not Hi Fi, it is heavy metal. Many do not like that sound, others do.
As said, EL84 15-18W... 6V6 if you want 20-30W if you abuse the max B+ is possible. So many great circuits out there. The AC15 and the Tweed Deluxe are 2 of the most famous amps ever. Both are what you are looking for.
I want to build a power amp . Only clean volume To add pedals for preamp sections . . I search and I found the Chinese mooer TE-20 .. I don’t find the schematic but I found that have 2x el84 - 1x ecc83 and 1x ecc81 …for overdrive amps I build my Marshall clone 1974x( 18 watts) and the orange clone dark terror (7 and 15 watts ) . Now I need to build a clean power amp .
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Fender blues junior, half power Vox AC30 & Peavey Classic 30.
Pedal platform might help in your Google search.
Pedal platform might help in your Google search.
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I found it but I have some questions .. https://el34world.com/charts/Schematics/files/Mesa_boogie/Boogie_20_20_poweramp.pdf
Some parts ( resistors and caps ) say for value , I.e. 120R 10watt but for some other it doesn’t say .. for what it does not mention, it is 1/2 watt for resistors and 400v for caps ? And what is that with 10x 330R resistors in series between A voltage and B ?? Is right ?
Some parts ( resistors and caps ) say for value , I.e. 120R 10watt but for some other it doesn’t say .. for what it does not mention, it is 1/2 watt for resistors and 400v for caps ? And what is that with 10x 330R resistors in series between A voltage and B ?? Is right ?
Yes, 1/2W and 400V should do ok for the unmarked parts.
That long resistor string is ridiculous though, so just use a single 3.6k 1W resistor instead.
That long resistor string is ridiculous though, so just use a single 3.6k 1W resistor instead.
Ok that’s fine .. and tell me how to find what mA are the voltage cable ( secondary coil of transformer )?
Send input jack straight to P1 and call it "Volume"
Replace 5Y3 with a couple 1N4007 and lower suggested PT voltage to compensate that.
Say 220+220V secondary, not highervthan 2 x 240V, you won´t need the 5V filament winding.
If you need "just the power amp", here or in a Fender/Marshall/Vox circuit, floor pedals will have difficulty drving them, if at all, play it safe and keep *one* gain stage in between.
That schematic is a minefield, full of errors (and it´s a "Factory" 🙄 😎 😱 schematic, go figure)
330Vac secondaries give you raw +466V 😱; dropping them to +390V at power tube plates is crazy, or at least very poor engineering, besides being crazy dangerous.
Imagine you pull *one* powr tube, or it simply goes off for any reason.
The Presence pot circuit is NONSENSE.
WHY 47k//10k at the input?
Rayma already mentioned the crazy 330 ohm dropper string.
Bet will find more if I decide to waste time on it.
Yes you are correct .. now I see it’s little strange schematic … so I’m looking for your schematic ( Phoenix ) .. tell me something : 1st: I keep the schematic pure .. I use the the 1st stage preamp ,, need to make the main transormer more volts from 220+ 220 as you saying ? Like it say the diagram 298+298 I mean .
2nd : how much watt it is and how much ohm speaker need ? I think 8 ohm but for sure . 😛
And on 1N4007 bridge need to put caps ?
2nd : how much watt it is and how much ohm speaker need ? I think 8 ohm but for sure . 😛
And on 1N4007 bridge need to put caps ?
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plig88,
Questions:
Is this guitar power amp for use as a:
Jazz guitar?
An entertainer in a small night club?
As a practice amp?
For a large auditorium?
For an Outdoor concert?
To Playback a Guitar recording?
Etc.
Define a target.
Take Aim.
Hit the target.
We are already on Post # 19.
Questions:
Is this guitar power amp for use as a:
Jazz guitar?
An entertainer in a small night club?
As a practice amp?
For a large auditorium?
For an Outdoor concert?
To Playback a Guitar recording?
Etc.
Define a target.
Take Aim.
Hit the target.
We are already on Post # 19.
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Sorry, missed bottom 2 lines.
The "Phoenix" is actually a Dr Z Carmen Ghia but they didn´t want to infringe on the brand.
Killer *simple* amp (2 knobs), that´s why I suggested it.
A little red monster! The Dr. Z Carmen Ghia 18 watt EL84 head! With a Fender CS Masterbuilt Tele! - YouTube
Personally I would build it in full, to use as flat power amp add a switching jack feeding the volume pot and bypassing first pramp stage, BUT you can also use it on its own in an emergency.
220+220VAC with SS rectifiers will give you needed ~300V DC
YOU asked for EL84 and "20W" so I suggested closest I could find.
Speaker impedance?:
you will buy an "18-20W" 2 x EL84 transformer which will have 4-8-16 ohm taps, at least 2 of them, use the one matching your speakers.
EDIT: 5751 is a tamer, supposedly premium 12AX7 sister, I would straight use 12AX7 or 12AT7 which are easily available.
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