Melody 400W Power Amplifier

Ermac · 14th July 2009, 03:54 PM

Hi everyone,

Does anyone have built this amp so far?
It looks good to me. I want to either build this or LYNX-3.

Which one do you suggest?

Would someone please clarify me why powerAms having an opamp in their first stage aren't so popular?(like PA-300 from Elektor)

Regards!
Ermac

Ermac · 15th July 2009, 07:42 AM

Here's the schematic:

AndrewT · 15th July 2009, 08:55 AM

it looks to me that someone has redrawn this with a 4pair output stage. They have increased the supply voltage without regard to what voltage suits the transistors specified.
It uses driver devices for the pr-driver and Vbe multiplier.
And uses driver devices for the VAS.
These devices should be low Cob, high gain (at low current), High fT at low current, high Vce0
Most of the voltage amp stage uses 546/556 these are 65V devices.
Do you really expect all of them to survive 140V? (i.e. Vc + |Ve| = 70+70 = 140)

Ermac · 15th July 2009, 09:53 AM

It can be used with 50-0-50V supply.

AndrewT · 15th July 2009, 10:17 AM

using +-50Vdc it becomes a 200W amplifier with the wrong devices specified.

Ermac · 15th July 2009, 10:36 AM

I think using four pair output devices is for lowering the load down to 2 ohms.

AndrewT · 15th July 2009, 11:12 AM

yes. 4pair of mJ14003/4 kept cool can drive a 2ohm speaker load from +-50Vdc.
If sufficient smoothing is fitted and a high dissipation heatsink is used, you may get 400W into 2ohms

Ermac · 15th July 2009, 11:41 AM

Quote:

Originally posted by AndrewT
yes. 4pair of mJ14003/4 kept cool can drive a 2ohm speaker load from +-50Vdc.
If sufficient smoothing is fitted and a high dissipation heatsink is used, you may get 400W into 2ohms

Exactly, I want to do so! But I hesitate whether build LYNX3.0 or Melody. LYNX with opamp in its fisrt stage and Melody with transistors... Which one do you suggest?

AndrewT · 15th July 2009, 11:53 AM

I don't know either amplifier, but the Melody with inappropriate transistors specified at various locations can hardly be recommended.

Ermac · 15th July 2009, 11:56 AM

Ok, thank you for your input and ideas.

14th July 2009, 03:54 PM	#1
Ermac diyAudio Member Join Date: Dec 2008	Melody 400W Power Amplifier Hi everyone, Does anyone have built this amp so far? It looks good to me. I want to either build this or LYNX-3. Which one do you suggest? Would someone please clarify me why powerAms having an opamp in their first stage aren't so popular?(like PA-300 from Elektor) Regards! Ermac

15th July 2009, 08:55 AM	#3
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	it looks to me that someone has redrawn this with a 4pair output stage. They have increased the supply voltage without regard to what voltage suits the transistors specified. It uses driver devices for the pr-driver and Vbe multiplier. And uses driver devices for the VAS. These devices should be low Cob, high gain (at low current), High fT at low current, high Vce0 Most of the voltage amp stage uses 546/556 these are 65V devices. Do you really expect all of them to survive 140V? (i.e. Vc + \|Ve\| = 70+70 = 140) __________________ regards Andrew T.

15th July 2009, 10:17 AM	#5
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	using +-50Vdc it becomes a 200W amplifier with the wrong devices specified. __________________ regards Andrew T.

15th July 2009, 11:12 AM	#7
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	yes. 4pair of mJ14003/4 kept cool can drive a 2ohm speaker load from +-50Vdc. If sufficient smoothing is fitted and a high dissipation heatsink is used, you may get 400W into 2ohms __________________ regards Andrew T.

15th July 2009, 11:53 AM	#9
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	I don't know either amplifier, but the Melody with inappropriate transistors specified at various locations can hardly be recommended. __________________ regards Andrew T.


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15th July 2009, 09:53 AM	#4
Ermac diyAudio Member Join Date: Dec 2008	It can be used with 50-0-50V supply.

15th July 2009, 10:36 AM	#6
Ermac diyAudio Member Join Date: Dec 2008	I think using four pair output devices is for lowering the load down to 2 ohms.

15th July 2009, 11:56 AM	#10
Ermac diyAudio Member Join Date: Dec 2008	Ok, thank you for your input and ideas.

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