Amplifier Goliath!

viktor1986 · 26th June 2005, 12:09 AM

Hi,my english is not good,so try too understand me.What could you tell me about this amplifier?Is it good?

Greg Erskine · 26th June 2005, 01:02 AM

hi viktor1986,

Your english is good, perfect in fact.

How about a few links to the Goliath in question? (You've got to make it easy)

diyman · 26th June 2005, 09:22 AM

If my memory is okay, I believe the design is more of less identical to the Crescendo Amp published by Elektor in the 80s except the OP Mosfets had been changed from Hitachis to IRFs. Original amp sounded pretty okay though not outstanding.

My 2 cts.

ckt

AndrewT · 26th June 2005, 09:51 AM

Hi,
the bias resistor needs to be changed to a temperature compensating bias voltage. Diodes on the main heatsink or Vbe (Vgs) multiplier. A dual complementary Vgs multiplier as Borbely may be the best option.
The input cap seems a bit small RC = 33mS.
The LTP current seems a bit low about at about 760uA, only 380uA per leg if balanced.
Gate source zeners direct across the FET legs would be better maybe 7V to 9V then the 220r current limits the zener on overload. But it still won't survive a short circuit. Needs short protection on the VAS transistors.
Leave an extra route for the Hi Frequency feedback capacitor to the bases of the inverting LTP pairs. and maybe space for an RC combination in // to the 47pF

The rest of the circuit seems well designed, e.g. good separation of power and signal grounds.

viktor1986 · 26th June 2005, 11:01 AM

Here is a link:

http://www.bas.abshost.net/mojiprojekti1.html

Go on "pojacala" and than on Goliath or another amplifier

The bias resistor is now 1k.

jacco vermeulen · 26th June 2005, 12:28 PM

With all this stuff coming from Serbia and Croatia maybe i should make an effort to learn to read the language.
I am really looking forward to the details of the 60watt class A amplifier(on the power amplifier current project list).

Using L-brackets to couple drivers and output Hitachi Mosfets is a very original idea, Sigma amplifier.
I have been thinking of building Dr. Jagodic's SMPS.

High time DIYaudio had a special thread for links to pages like the one from Dr. Jagodic.

viktor1986 · 26th June 2005, 04:36 PM

Could you tell me something more about this amplifier?How it work's?

I am not sure,I am in confusion,maybe I will built Legend amplifier with 8 IRFP250.What is better?

viktor1986 · 26th June 2005, 06:15 PM

Here is a schematic of Legend.I will use 8 IRFP250.

Goliath or Legend?

viktor1986 · 27th June 2005, 05:49 PM

Please Goliath or Legend?

Netlist · 27th June 2005, 06:00 PM

Quote:

Originally posted by viktor1986
Please Goliath or Legend?

What speakers are you going to use?

/Hugo

26th June 2005, 01:02 AM	#2
Greg Erskine diyAudio Member Join Date: Jan 2002 Location: Sydney/Australia	hi viktor1986, Your english is good, perfect in fact. How about a few links to the Goliath in question? (You've got to make it easy) __________________ Greg Erskine

26th June 2005, 09:22 AM	#3
diyman diyAudio Member Join Date: Nov 2001 Location: Malaysia	Goliath If my memory is okay, I believe the design is more of less identical to the Crescendo Amp published by Elektor in the 80s except the OP Mosfets had been changed from Hitachis to IRFs. Original amp sounded pretty okay though not outstanding. My 2 cts. ckt

26th June 2005, 09:51 AM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, the bias resistor needs to be changed to a temperature compensating bias voltage. Diodes on the main heatsink or Vbe (Vgs) multiplier. A dual complementary Vgs multiplier as Borbely may be the best option. The input cap seems a bit small RC = 33mS. The LTP current seems a bit low about at about 760uA, only 380uA per leg if balanced. Gate source zeners direct across the FET legs would be better maybe 7V to 9V then the 220r current limits the zener on overload. But it still won't survive a short circuit. Needs short protection on the VAS transistors. Leave an extra route for the Hi Frequency feedback capacitor to the bases of the inverting LTP pairs. and maybe space for an RC combination in // to the 47pF The rest of the circuit seems well designed, e.g. good separation of power and signal grounds. __________________ regards Andrew T.

26th June 2005, 11:01 AM	#5
viktor1986 diyAudio Member Join Date: Jun 2005 Location: Belgrade, Serbia	!!! Here is a link: http://www.bas.abshost.net/mojiprojekti1.html Go on "pojacala" and than on Goliath or another amplifier The bias resistor is now 1k. __________________ Pa mislim sta reci!

26th June 2005, 12:28 PM	#6
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	With all this stuff coming from Serbia and Croatia maybe i should make an effort to learn to read the language. I am really looking forward to the details of the 60watt class A amplifier(on the power amplifier current project list). Using L-brackets to couple drivers and output Hitachi Mosfets is a very original idea, Sigma amplifier. I have been thinking of building Dr. Jagodic's SMPS. High time DIYaudio had a special thread for links to pages like the one from Dr. Jagodic. __________________ Looks like Sponge Bob has killed another thread.


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27th June 2005, 05:49 PM	#9
viktor1986 diyAudio Member Join Date: Jun 2005 Location: Belgrade, Serbia	!!! Please Goliath or Legend? __________________ Pa mislim sta reci!

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