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Convert an Adcom 5500 to Aleph J?
Convert an Adcom 5500 to Aleph J?
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Old 15th July 2018, 02:36 AM   #1
Jeffreyjuice is offline Jeffreyjuice
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Default Convert an Adcom 5500 to Aleph J?

I recently picked up, in great condition, an Adcom 5500 thinking i would use the chassis and power supply to house an Aleph J clone I've been wanting to build. The chassis has plenty of heat-sink and all the connections I would want. But in my haste i neglected to check the power supply schematic... I was seduced by the gleaming pics of BEER CAN SIZE CAPS! 60 Volts DC is way too much for the Aleph J.

1. Is it possible to replace the transformer with a lower voltage transformer, maybe even two (one for each channel) and use the existing PSU circuitry?
2. I was planning on selling the power amp boards on Ebay, should I sell off the complete power supply and build my own? (it'll be difficult parting with 4 18,000uF Capacitors!)
3. Build speakers that will handle the 200 watts per channel and enjoy the Adcom 5500 in it original glory?

It's worth mentioning option three might not pass the partner test as I am just completing, quite slowly, some very reasonable sized diy bookshelf speakers to replace some old Sansui sp200's that a driver went on.

I have very good electronics building and modification skills but circuit design is a bit over my head currently. Any help is greatly appreciated!
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Old 15th July 2018, 05:25 PM   #2
Nelson Pass is offline Nelson Pass  United States
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Convert an Adcom 5500 to Aleph J?
If your transformer is also tapped for 240V and you run that at 120V,
then you can think in terms of 30V rails. This is close to the maximum
rating of the Jfets, though, so if you want to drop the voltage a bit with
an RC filter, that would give you 2 benefits.

Looks like your transformer has the dual primary coils....
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Old 15th July 2018, 09:01 PM   #3
Zen Mod is online now Zen Mod  Serbia
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Convert an Adcom 5500 to Aleph J?
as Pa said

then look at Babelfish J thread for recipes about cascoding , not matching or matching and 42
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Old Yesterday, 06:12 AM   #4
Jeffreyjuice is offline Jeffreyjuice
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Holy Smokes! Nelson Pass himself is the first response to my inquiry! And with such a great suggestion, Thanks Nelson!

Quote:
Looks like your transformer has the dual primary coils....
I was under the impression that you designed this amp..?

Then Zen Mod jumps in WOW! ZM i am 10 pages into babelfish j and most of it's over my head. Can a 50 WPC version of this be built? and are pc boards still availible?
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Old Yesterday, 06:58 AM   #5
levistubby is offline levistubby  United Kingdom
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If the Adcom 5500 is in full working order, it seems a shame to destroy it, especially if using some of its parts results in a less than optimal new build..
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Old Yesterday, 07:35 AM   #6
gadut is online now gadut  Indonesia
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Quote:
Originally Posted by levistubby View Post
If the Adcom 5500 is in full working order, it seems a shame to destroy it, especially if using some of its parts results in a less than optimal new build..
Agree...

why not building a completely new set on AlephJ?
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Old Yesterday, 10:04 AM   #7
Zen Mod is online now Zen Mod  Serbia
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Convert an Adcom 5500 to Aleph J?
Quote:
Originally Posted by Jeffreyjuice View Post
Holy Smokes! Nelson Pass himself is the first response to my inquiry! And with such a great suggestion, Thanks Nelson!



I was under the impression that you designed this amp..?

Then Zen Mod jumps in WOW! ZM i am 10 pages into babelfish j and most of it's over my head. Can a 50 WPC version of this be built? and are pc boards still availible?
sky is the limit , with Aleph topology

pcbs are not a problem

though - reconsider what other Greedy Boyz are saying - maybe is best to sell Adcom as is , and then invest in new hardware
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Old Yesterday, 05:18 PM   #8
Nelson Pass is offline Nelson Pass  United States
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Convert an Adcom 5500 to Aleph J?
Quote:
Originally Posted by Jeffreyjuice View Post
Holy Smokes! Nelson Pass himself is the first response to my inquiry! And with such a great suggestion, Thanks Nelson!
Low hanging fruit.

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Old Today, 12:01 AM   #9
Jeffreyjuice is offline Jeffreyjuice
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@Levistubby and Gadult my plan is to build "NEW" Aleph J boards into the Adcom 5500 hardware. A chassis and the connectors alone cost nearly double what I picked up the Adcom for. Plus someone will be able to purchase some very reasonably priced boards to restore their once beloved 5500. I'm not sure how his is a shame since two people will now be enjoying music they love. Keeping the 5500 is a stretch for me since I'm looking to build an amp, or two maybe twenty, and really want to stay in the 25 to 50 WPC range. Frankly, the only reason I'm looking to keep the power supply is that it just looks so solidly built that I'd like to try out re-using it. Should the PS prove disappointing, oh well it'll just be another project!
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Old Today, 01:05 AM   #10
Zen Mod is online now Zen Mod  Serbia
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Convert an Adcom 5500 to Aleph J?
it sez power consumption 1400W , which means xformer is good for at least 1K2

if you run two 115Vac primaries in series , on 115Vac mains (as Pa advised) , xformer could bring half power of said 1K2 , so aroundish 600W

say that you're good up to 150W of heat per side (maybe with little Babysitter help) , and that xformer can cover that

so , you're in bracket of 50W Aleph

though , 4pcs of 18mF ......... that's on sissy side , you'll need more for intended Iq
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