Looking For a Discrete 50w+amp Project useing Parts I have???

Minion · 10th June 2007, 08:13 PM

Hi, I am looking for a Power amp schematic that would utilize some of the Parts I have which would be suitable as the Power stage for a Guitar or Bass amp running 8 Ohm speakers....

I happen to have quite a few Transistors that would be suitable as output stages and have a couple good Power Transformers (30v,0v,30v-200vA) that should be adequate for building an amp in the 75w range and I have lots of Parts but I am haveing trouble finding a suitable Schematic/Project that would utilize the Parts I have available so I am here to ask you good Folks if you could maybe point me in the right Direction.......

Here are some of the Transistors I have:
MJ11016/MJ11015 30A 120v 200w To-3 Darlingtons
MJE3055/MJE2955 70v 10A To-220
Tip31C/32C 100v 5A To-220
Tip41C/42C 100v 7A? To-220
BD139 80V 1.5A SOT-32
BC550C/560C 50V 100mA T0-92
2N4401/4403 40v 600ma T0-92
2N3904/3906 T0-92
2N2222A T0-92
IRF630 200v 9A N CH-Mosfet T0-220
RFP8P08 80v 8A P-Ch Mosfet To-220

And I have some Various other Small signal Transistors and some J-fets and all the Caps and resistors and PCB material I need, or at least for the most Part......

So if someone knows of a Guitar/Bass amp project that will utilize the Parts I have or even a Power amp stage that would be awesome.......

Thanx a Lot.....

Cheers

sixtek · 10th June 2007, 09:05 PM

Hi,

Try ST151. Short circuit-protected, 50...60W-RMS on 8Ohm, cheap parts but good quality.
http://sixtek.uw.hu/st151.html

Schema:
http://sixtek.uw.hu/st151_krajz.pdf
PCB and placing:
http://sixtek.uw.hu/st151_nyak.pdf
http://sixtek.uw.hu/st151_beult.pdf

Quiescent current 30mA, adjusted with P1.

30-0-30 mains transformer will be just excellent.
Use your MJE2955/3055's (selected to 80V Vceo) as OP devices, and BC550/560's instead of BC547/557's. As drivers BD139/BD140 or the slow TIP31C/TIP32 will do the job.
As VAS and Vbe transistor let's use BD140 and BD139.
Then the two pair of MJE OP devices's SOA for 50W/8Ohm will be OK.

Good luck,

Leolabs · 11th June 2007, 02:28 AM

4 ohms OK????

sixtek · 11th June 2007, 08:39 AM

Quote:

Originally posted by Leolabs
4 ohms OK????

You mean ST151?

Then my answer is yes, that's absolutely OK. The amplifier designed to 4...8 Ohm speaker impedance.
See homepage: "100W/4Ohm, 60W/8Ohm"

Minion · 11th June 2007, 04:34 PM

Thanx for the Link to the ST151, Looks like it is what I am looking for accept I don"t have any BD140"s (Just a bunch of BD139 NPN), Could I use a BC139 in Place of a BD140 and Just switch the Colector for the Emiter???

Thanx

sixtek · 11th June 2007, 06:27 PM

Hi,

No, NOT! Don not try that crazy modification unless you want some smoke

Use TIP32C in place of BD140.

Minion · 11th June 2007, 06:51 PM

Thanx a Lot......I"ll give it a shot and see how it work out and let you know....

Cheers

dvisves · 11th June 2007, 07:23 PM

Looking at the power transistors you have,why not buy an LM391 driver IC from SGS Thomson .The circuit is readily available on line.I have built few of this amps.They are short circuit proof and have very low distortions.Of course the heat sinks will have to be large.

jaycee · 11th June 2007, 08:09 PM

If you only want 50W into 4 ohms, then you could drop the power rails to 25V.

You can then use BC550 in place of BC557, use TIP32C for T3, TIP31C for T6, BD139 for T4, TIP41C/42C for T7/T11, and MJE3055/MJE2955 for T8-9/T12-13.

Really what would be best is if you could get BD140 for use as the VAS... or even MJE350.

sixtek · 11th June 2007, 08:14 PM

Dvisves,

Minion haven't got LM391...
And on the margin that IC is obsolete.

Cheers,

10th June 2007, 08:13 PM	#1
Minion diyAudio Member Join Date: May 2006	Looking For a Discrete 50w+amp Project useing Parts I have??? Hi, I am looking for a Power amp schematic that would utilize some of the Parts I have which would be suitable as the Power stage for a Guitar or Bass amp running 8 Ohm speakers.... I happen to have quite a few Transistors that would be suitable as output stages and have a couple good Power Transformers (30v,0v,30v-200vA) that should be adequate for building an amp in the 75w range and I have lots of Parts but I am haveing trouble finding a suitable Schematic/Project that would utilize the Parts I have available so I am here to ask you good Folks if you could maybe point me in the right Direction....... Here are some of the Transistors I have: MJ11016/MJ11015 30A 120v 200w To-3 Darlingtons MJE3055/MJE2955 70v 10A To-220 Tip31C/32C 100v 5A To-220 Tip41C/42C 100v 7A? To-220 BD139 80V 1.5A SOT-32 BC550C/560C 50V 100mA T0-92 2N4401/4403 40v 600ma T0-92 2N3904/3906 T0-92 2N2222A T0-92 IRF630 200v 9A N CH-Mosfet T0-220 RFP8P08 80v 8A P-Ch Mosfet To-220 And I have some Various other Small signal Transistors and some J-fets and all the Caps and resistors and PCB material I need, or at least for the most Part...... So if someone knows of a Guitar/Bass amp project that will utilize the Parts I have or even a Power amp stage that would be awesome....... Thanx a Lot..... Cheers

11th June 2007, 07:23 PM	#8
dvisves diyAudio Member Join Date: May 2007	Looking at the power transistors you have,why not buy an LM391 driver IC from SGS Thomson .The circuit is readily available on line.I have built few of this amps.They are short circuit proof and have very low distortions.Of course the heat sinks will have to be large. __________________ deevee

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10th June 2007, 09:05 PM	#2
sixtek diyAudio Member Join Date: Jan 2007	Hi, Try ST151. Short circuit-protected, 50...60W-RMS on 8Ohm, cheap parts but good quality. http://sixtek.uw.hu/st151.html Schema: http://sixtek.uw.hu/st151_krajz.pdf PCB and placing: http://sixtek.uw.hu/st151_nyak.pdf http://sixtek.uw.hu/st151_beult.pdf Quiescent current 30mA, adjusted with P1. 30-0-30 mains transformer will be just excellent. Use your MJE2955/3055's (selected to 80V Vceo) as OP devices, and BC550/560's instead of BC547/557's. As drivers BD139/BD140 or the slow TIP31C/TIP32 will do the job. As VAS and Vbe transistor let's use BD140 and BD139. Then the two pair of MJE OP devices's SOA for 50W/8Ohm will be OK. Good luck,

11th June 2007, 02:28 AM	#3
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	4 ohms OK????

11th June 2007, 04:34 PM	#5
Minion diyAudio Member Join Date: May 2006	Thanx for the Link to the ST151, Looks like it is what I am looking for accept I don"t have any BD140"s (Just a bunch of BD139 NPN), Could I use a BC139 in Place of a BD140 and Just switch the Colector for the Emiter??? Thanx

11th June 2007, 06:27 PM	#6
sixtek diyAudio Member Join Date: Jan 2007	Hi, No, NOT! Don not try that crazy modification unless you want some smoke Use TIP32C in place of BD140.

11th June 2007, 06:51 PM	#7
Minion diyAudio Member Join Date: May 2006	Thanx a Lot......I"ll give it a shot and see how it work out and let you know.... Cheers

11th June 2007, 08:09 PM	#9
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	If you only want 50W into 4 ohms, then you could drop the power rails to 25V. You can then use BC550 in place of BC557, use TIP32C for T3, TIP31C for T6, BD139 for T4, TIP41C/42C for T7/T11, and MJE3055/MJE2955 for T8-9/T12-13. Really what would be best is if you could get BD140 for use as the VAS... or even MJE350.

11th June 2007, 08:14 PM	#10
sixtek diyAudio Member Join Date: Jan 2007	Dvisves, Minion haven't got LM391... And on the margin that IC is obsolete. Cheers,

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