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Old 20th June 2002, 10:37 PM   #21
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I would say so. Anywhere from 30v dc to 50 like somebody else I know of, will work. Just remember the changes I recomended, an extra diode, BF469 in Q3 with 68pF cap for C2 and the Toshiba 2SC5200/2SA1943 outputs on Q6 & Q7. You can download the schematic on the previous page and get the boards from RCS. You will find it all in the previous correspondence.
And, don't forget to post your impressions here for others to see!
Cheers,
tomcat
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Old 29th March 2008, 08:50 AM   #22
Muff is offline Muff  Australia
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This is a very old thread, but I wanted to mention that the digi125
will give impressive results when the motorola MJ802 MJ4502 outpud devices are used in place of the standard drivers and configure four of the digi125`s as bridged pairs, I built this amp around fifteen years ago and it has given stunning performance without any of the high frequency instability that can affect the amp when constructrd in its default configuration. Its driving a single pair of three way speaker cabinets with fifteen inch drivers,
and sounds transparent but if needed (parties or whatever) I can ramp it up, actually the room on the opposite side of the wall the speakers are in front of has to have the pictures taken down or they get blown off
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Old 8th April 2008, 05:25 AM   #23
jaya000 is offline jaya000  India
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Toshiba 2SC5200/2SA1943 or motorola MJ802 MJ4502?
Which will be better?
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Old 8th April 2008, 07:13 AM   #24
GK is offline GK  Australia
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Wow! this brings back memories.
I've got the original ETI magazine featuring the DIGI-125, bought when I was a high school student.

Sorry to say it, but it really isn't a good design. Class B operation of the output devices and TO-92's as drivers for the low fT TO3 outputs! The whole thing was also packed on a tiny circuit board with really narrow tracks for the high current paths.

I think the ETI-480 with the four output device option is a better design than this.
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Old 8th April 2008, 09:23 AM   #25
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Quote:
Originally posted by jaya000
Toshiba 2SC5200/2SA1943 or motorola MJ802 MJ4502?
Which will be better?
I used Toshiba 2SC5200/2SA1943.

regards
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Old 8th April 2008, 09:28 AM   #26
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Quote:
Originally posted by G.Kleinschmidt
Wow! this brings back memories.
I've got the original ETI magazine featuring the DIGI-125, bought when I was a high school student.

Sorry to say it, but it really isn't a good design. Class B operation of the output devices and TO-92's as drivers for the low fT TO3 outputs! The whole thing was also packed on a tiny circuit board with really narrow tracks for the high current paths.

I think the ETI-480 with the four output device option is a better design than this.
Hi Glen,

I'm not sure if this PCB is close to the original, but on 25VDC rails I found the VAS transitors to be the one to worry about heat wise.

I was surprised, with a few mods, this simple amp sounded quite good. I preferred it to the Gainclones I was builting at the time. It definitely responded well to a little more bias and a bootstrap on the VAS.

BTW: The power traces are quite thin as you mentioned.

regards
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Old 8th April 2008, 11:34 AM   #27
jaya000 is offline jaya000  India
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Quote:
I was surprised, with a few mods, this simple amp sounded quite good. I preferred it to the Gainclones I was builting at the time. It definitely responded well to a little more bias and a bootstrap on the VAS.
Give details about what mod u did.
Preferably schematics.
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Old 8th April 2008, 11:42 AM   #28
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Hi jaya00,

Just use the search facility, it was all covered about 4 years ago.

regards
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Old 10th April 2008, 09:44 AM   #29
Muff is offline Muff  Australia
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The digi125 is a class A amplifier, confirmed when I contacted the designer Graham Dicker.
He sent me instructions with the last batch of boards I purchased last year, for a 200watt version which uses the MJ15003/004 devices, however in this form the Amp is in class B operation.
If anyone wants the instruction I can post them here.
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Old 10th April 2008, 10:12 AM   #30
ilimzn is offline ilimzn  Croatia
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Based on the posted schematic, this amp has rather undefined bias, which is likely class B or could even be said it's class C depending on what transistors one uses. The 'floating base' darlingtons do not inspire confidence either.
There is a quote attributed to Alber Einstein: Things should be as simple as possible, but no simpler. Well, it seems to me this amplifier attempts to be simpler.
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