| Tyimo |
Hi!
I was looking for a nice and simple SE amp with one ECL82 per side and found two attractive circuits.
I would like ask the experts about these designs:
-are they operate in Class A?
-has any negative fead back in the circuits?
-which one is better? :-)
Thanks and greets:
Tyimo |
|
|
| Tyimo |
Here is the another competitor!
:cop: Note. Power supply removed from schema -- to dangerous to contemplate |
|
|
| PRR |
> -are they operate in Class A?
Yes, obviously.
> -has any negative fead back in the circuits?
No. (I won't count the cathode resistor in the first one.)
> -which one is better? :-)
They are essentially THE SAME. Draw them both in the same style: very minor differences.
One BIG difference: #1 does not show a power supply, #2 does, and the #2 power supply as drawn is a death trap!!! It shows one side of the wall-power line connected to chassis. There no indication which side is utility-ground. It is uncertain which wall-socket pin is grounded (60% of my kitchen outlets had black and white reversed). The chassis is exposed to the users at the input connector, which makes the whole hi-fi system "electrically HOT". It can kill you or your children. And as drawn, turning the power switch Off ensures that the chassis will be "hot". Do not build that power supply as shown!!! |
|
|
| Giaime |
| Please moderators, remove that awfully dangerous schematic, as PRR said. :hot: |
|
|
| Tyimo |
| And here is the first one's PSU: |
|
|
| Giaime |
| quote: | Originally posted by Tyimo
Giaime: here is a corrected schem. |
That is always no-good, the B+ runs directly from the mains. You should use an isolation trasformer between the diode and the mains, to mantain safety rules. And also a half wave rectifier is no good. Try to redesign the PSU using PSUDesigner. |
|
|
| kevinkr |
I think I would just build the more recent of the two circuits, supply decoupling looks to be marginally better in the newer design.
If you do build the earlier one do get a power transformer with about a 180-200V secondary as well as a filament winding. You can use a bridge rectifier, bear in mind the original halfwave rectifier would have dropped significantly more voltage than a full wave bridge.
The old power supply design as previously stated is extremely hazardous to put it mildly.:bigeyes:
Kevin |
|
|
| choky |
search for "Aleksandar Kitic" in this forum.
LH84 (if I remember OK ) looks promising |
|
|
| Tyimo |
Hi!
| quote: | | the B+ runs directly from the mains |
Giaime! Yes, you are right! I looked only the main-audio circuit section and not the whole circuit with the PSU... That PSU design was realy a "deadly joke" Thanks for the moderators that removed it from the schematic!
Kevin: Thanks! Which one do you mean: the Noel82, with coloured schem ? I would anyway build a better PSU for this amp.
Greets:
Tyimo |
|
|
| Tyimo |
| quote: | | How about Morse's Gnat? |
Thanks Dave! Very interesting thread.
Tyimo |
|
|
| kevinkr |
Hi Tyimo,
Yes I meant the Noel82, but many of the links provided here lead to equally good designs. :D I think for a little added complexity that an SE design featuring EL84 and ECC83 or similar would be even better.
Kevin |
|
|
| Tyimo |
Hi Kevin!
Yes, a SE design featuring EL84 and ECC83 would be more discrete and could sound better, but than I would rather build a Parallel SE amp with one ECC83 and two EL84 to get a bit more output power and lower output impedance...this could be another thread :-)
Have you any idea?
Tyimo |
|
|
|
