I've built several of theese. They are derived from something like a PA-600 originally published in Elrad many years ago. It's an easily scalable concept.
I made my own PCB layout and replaced the complete protection circuit. Due to the simplicity of the circuit, they are reliable and easy to build.
They exactly sound the way you would expect a "opamp input stage high feedback bipolar amplifier" to sound: somewhat compressed, a bit cold... IMHO, they are ok for PA use, especially for the low frequency range in active setups. Keeping big woofers under control is their strength.
If you need an amp for your band or party room, there you go. Use a bigger transformer and add some big caps in the power supply, though.
However, if you need an amp for your high end system, check the PassLabs designs.
Best regards, Oliver
I made my own PCB layout and replaced the complete protection circuit. Due to the simplicity of the circuit, they are reliable and easy to build.
They exactly sound the way you would expect a "opamp input stage high feedback bipolar amplifier" to sound: somewhat compressed, a bit cold... IMHO, they are ok for PA use, especially for the low frequency range in active setups. Keeping big woofers under control is their strength.
If you need an amp for your band or party room, there you go. Use a bigger transformer and add some big caps in the power supply, though.
However, if you need an amp for your high end system, check the PassLabs designs.
Best regards, Oliver
Schematic
Could you send a schematics to this forum, this will be great. I have built a 50W current nfb IGBT amp ( replace IGBT by Hex Fets ). I had a lot of problems with it: cannot find a parts which pass to pcb, and a discription isn't good. I think T.Giesberts projects are too complicated, but if you like parameters ( thd < 0,0000....% ) those amps are very good.
Could you send a schematics to this forum, this will be great. I have built a 50W current nfb IGBT amp ( replace IGBT by Hex Fets ). I had a lot of problems with it: cannot find a parts which pass to pcb, and a discription isn't good. I think T.Giesberts projects are too complicated, but if you like parameters ( thd < 0,0000....% ) those amps are very good.
I've got the whole PA-300 article, 1.7MB/pdf - but not in english, sorry. Schematic, PCB, placing, measurements are included.
Anyone who is interested let's throw me a mail and then I send you the article.
alf_audio@inbox.com
Anyone who is interested let's throw me a mail and then I send you the article.
alf_audio@inbox.com
Hello Supernet,
I have built about 10 modules based on the Elektor circuit pa300
using MJ15003/4 they sound good and are reliable. I also use them in the amps i hire out and i get good comments from clients who hire them. One word of caution when using the ne5534
op amp you must connect a 47pf cap fron pin 6 to pin 2 of the op
amp or the module will oscillate. I am busy building the pa 600 at the moment and will post circuit and pictures as soon as i'm
finished.
I have built about 10 modules based on the Elektor circuit pa300
using MJ15003/4 they sound good and are reliable. I also use them in the amps i hire out and i get good comments from clients who hire them. One word of caution when using the ne5534
op amp you must connect a 47pf cap fron pin 6 to pin 2 of the op
amp or the module will oscillate. I am busy building the pa 600 at the moment and will post circuit and pictures as soon as i'm
finished.
Jacco, I respect your view, but I can't agree!
PA-300 looks good enough for general PA and HiFi purpouses, and nothing seems wrong arond the driver/OP stage.
I don't think that the linked design, called "Lynx" (that reminds me to Phase Linear 300 amplifier) would substantially beat PA-300's quality - except when used as a part of an audiophile system.
PA-300 looks good enough for general PA and HiFi purpouses, and nothing seems wrong arond the driver/OP stage.
I don't think that the linked design, called "Lynx" (that reminds me to Phase Linear 300 amplifier) would substantially beat PA-300's quality - except when used as a part of an audiophile system.
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