Please try it without load, that should be around 28V.
Because the heavy load that is why you measure a lower voltage all the way to the bridge rec.
400VA for both channel it gets compressed. That is what I think but maybe I am wrong.
Are you sure your transformer has 20VAC secondary
It can not be the bridge rec. Unless U pick up an old Selenium type (hard to find).
I see on the picture you use normal bridge rec. I would advise disconnecting everything (load including your cap. multip.) from the bridge and measure it that way. You will find faster what cause that much V drop.
Something fishy there but that can not be the bridge rec. that works or not that simple.
It can not be the bridge rec. Unless U pick up an old Selenium type (hard to find).
I see on the picture you use normal bridge rec. I would advise disconnecting everything (load including your cap. multip.) from the bridge and measure it that way. You will find faster what cause that much V drop.
Something fishy there but that can not be the bridge rec. that works or not that simple.
Hi Gaborbela,
You are correct, something is fishy here??
The transformer secondaries read 20.3V with no load on it at all.
When I connect the bridge rectifiers with no load on them, the reading is 19.8vdc?? If I connect the CMX to the rectifiers, the reading at the rectifiers outputs jumps to 22.5vdc? That does not seem right at all. The rectifiers are not new, I salvaged them out of an old amplifier probably about 20 years old.
Brain dead thermal safety shutoff for B.B.: 75C bimetallic switch with spade connectors and good for 10amps.
2 x 167F 75 Celsius Temperature Controlled Switch Thermostat KSD302 N.O | eBay
2 x 167F 75 Celsius Temperature Controlled Switch Thermostat KSD302 N.O | eBay
But the voltagedrop is too high and I think that might be caused by the too large capacitive load on the bridges. You can try to solve that by adding small resistervalue between bridge and large cans, but easiest testing probably is replacing the 47.000's for a smaller value. (or other rectifiers)
(I vaguely remember seeing a similar capacitive load problem on a bridge rectifier years ago in tubeheater supply, so if your transformer isn't 18V that might be case here too????)
(I vaguely remember seeing a similar capacitive load problem on a bridge rectifier years ago in tubeheater supply, so if your transformer isn't 18V that might be case here too????)
I made full turn on my build. Ordered 2 dell heatpipe-sinks also and place this build in 4u case with fans (if they fit inside). Now I can take my time to build those 2 bigger cases with huge sinks ready for BigBoy monoblocks, and cause theres nice option for fans, going to fit fans inside for hot summer days and control them with BB.
Juntuin,
Glad you will still be making the new big case for the B.B. it’s certainly big enough. Is it that you want to see the 20w one fired up and running or is that it needs its own case so you can have two amps?
I have an interesting story with the ALPHA20. My wife came down to my speaker lab last night and wanted to hear the new speakers that I just built. She rarely ever comes down let alone ask to listen. These are the 10F-8424 Scan Speak and RS225-8 transient perfect FAST speakers in newly built Baltic Birch cabinets. They are only 82.4dB at 2.83v and 1m. She asked me to play some of her own tunes from CDs and played them loud. Like nightclub loud, looking for distortion - she could not find any! She said these sound really really good and I want you to build a pair for the living room anyhow - just a testament that the amp (and speaker) can actually deliver the goods to my most difficult judge of sound quality. It really did sound good loud - I never turned up quite that loud before for fear of her saying it’s too loud and turn it down.
Glad you will still be making the new big case for the B.B. it’s certainly big enough. Is it that you want to see the 20w one fired up and running or is that it needs its own case so you can have two amps?
I have an interesting story with the ALPHA20. My wife came down to my speaker lab last night and wanted to hear the new speakers that I just built. She rarely ever comes down let alone ask to listen. These are the 10F-8424 Scan Speak and RS225-8 transient perfect FAST speakers in newly built Baltic Birch cabinets. They are only 82.4dB at 2.83v and 1m. She asked me to play some of her own tunes from CDs and played them loud. Like nightclub loud, looking for distortion - she could not find any! She said these sound really really good and I want you to build a pair for the living room
anyhow - just a testament that the amp (and speaker) can actually deliver the goods to my most difficult judge of sound quality. It really did sound good loud - I never turned up quite that loud before for fear of her saying it’s too loud and turn it down.
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This is a little different to what I remember doing long ago, but I am no engineer LOL
https://www.tme.eu/nl/Document/1e8c469bc0d7401251dff83ab1ec114b/gbi35a.pdf
https://www.tme.eu/nl/Document/1e8c469bc0d7401251dff83ab1ec114b/gbi35a.pdf
Hey X, I need 2-channels for my horns (Alpha 20) and 2-channels for mid/mass (there's BigBoy). 20 will replace ACA and BB replaces darTZeel someday (I don't like that amp anyway). If and when I'm going for passive system, I like to keep two good amps at hands. I'm pretty sure that I like these amps since Alephs have been my favorites
Based on your story it seems that Alpha20 can deliver more than you could imagine with that 20w
Forgot to ask again: is 2x30v (545va) trafo too much for BB to handle?
Based on your story it seems that Alpha20 can deliver more than you could imagine with that 20w
Forgot to ask again: is 2x30v (545va) trafo too much for BB to handle?
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She asked me to play some of her own tunes from CDs and played them loud. Like nightclub loud, looking for distortion - she could not find any! She said these sound really really good and I want you to build a pair for the living room
Now open CLUB X!! Right on
Those speakers sound interesting also.
Thanks Irribeo,
How small? I have .22r 3w resistors on hand.
I think I’ll swap the 47mfd caps for smaller ones also.
Regards