Don't need anything extra but the switch.
Hmmm... It's actually a very interesting idea. The biggest thing that immediately comes to mind is make sure it's powered off when you throw that switch, but aside that, It's not ringing any alarm bells in my head.
Start a thread, take a bunch of photos and go for it.
Hmmm... It's actually a very interesting idea. The biggest thing that immediately comes to mind is make sure it's powered off when you throw that switch, but aside that, It's not ringing any alarm bells in my head.
Start a thread, take a bunch of photos and go for it.
I don't like idea of switching high DC inrush currents
maybe using solid state relays, so small 3PDT toggle switch operating them
besides that , it comes to my mind - each channel (of 2+2) having own dedicated speaker , or you intend to drive just one pair , using different amp for different mood ?
maybe using solid state relays, so small 3PDT toggle switch operating them
besides that , it comes to my mind - each channel (of 2+2) having own dedicated speaker , or you intend to drive just one pair , using different amp for different mood ?
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I don't like idea of switching high DC inrush currents
Yes indeed, DC is difficult to switch safely.
6L6 addressed that adequately.
maybe using solid state relays, so small 3PDT toggle switch operating them
besides that , it comes to my mind - each channel (of 2+2) having own dedicated speaker , or you intend to drive just one pair , using different amp for different mood?
Good question. I've pondered having a system that could be readily switched from rock and roll amp/speakers to singer and guitar amp/speakers.
Bit of a stretch highly contingent on whether 2 pair speakers could be properly placed in the same listening area. At any rate, I'll have to wait until I retire to pursue the notion. Probably best to keep working toward a system that does everything well.
Don't need anything extra but the switch.
Hmmm... It's actually a very interesting idea. The biggest thing that immediately comes to mind is make sure it's powered off when you throw that switch, but aside that, It's not ringing any alarm bells in my head.
Start a thread, take a bunch of photos and go for it.
+1
Success!
Replaced Q2,3,4 in board #1.
Fired it up, and whaddaya know, readings across source resistor and DC offset were in the ballpark.
Did anybody hear my whoop and holler?
Adjusted R27 to .350v across source resistor, DC offset is .035v.
1/2 hr warmup, adjusted to .400v and .000v.
Lid on for another 1/2 hr; adjusted bias from.384 to .400, offset from.005 to .000.
Checked board #2 bias .378, adjusted to .400, offset from .005 to .000.
Power down, take the wife out to supper.
Power up, bias on both sides .430-ish, did not adjust, offsets .003-ish, did not adjust. Power down.
Connect test speakers and Spotify, power up and we have clean music from not one, but TWO channels.
Zero turn on thump, or noise of any kind. 1rst song through a new amp is a big deal, Jimi Hendrix got the job with "All Along the Watchtower".
Oooh-la-la, can't stop grinning.
Many thanks to the group for the help and encouragement.
Replaced Q2,3,4 in board #1.
Fired it up, and whaddaya know, readings across source resistor and DC offset were in the ballpark.
Did anybody hear my whoop and holler?
Adjusted R27 to .350v across source resistor, DC offset is .035v.
1/2 hr warmup, adjusted to .400v and .000v.
Lid on for another 1/2 hr; adjusted bias from.384 to .400, offset from.005 to .000.
Checked board #2 bias .378, adjusted to .400, offset from .005 to .000.
Power down, take the wife out to supper.
Power up, bias on both sides .430-ish, did not adjust, offsets .003-ish, did not adjust. Power down.
Connect test speakers and Spotify, power up and we have clean music from not one, but TWO channels.
Zero turn on thump, or noise of any kind. 1rst song through a new amp is a big deal, Jimi Hendrix got the job with "All Along the Watchtower".
Oooh-la-la, can't stop grinning.
Many thanks to the group for the help and encouragement.
Scored one of those Mega testers (thanks for the recommend, MJ) and ran Q2,3,4 through it.
Q2 hFE=186 Uf=618mV
Q3 hFE=216 Uf=652mV
Q4 No, unknown, or damaged part
Detailed analysis of the impact of a fugazi Q4 is beyond me, but as the board worked after it was replaced.....
Obviously, this little doo-dad will be used for screening all components it will read before they go into the next set of amp boards I solder up.
Q2 hFE=186 Uf=618mV
Q3 hFE=216 Uf=652mV
Q4 No, unknown, or damaged part
Detailed analysis of the impact of a fugazi Q4 is beyond me, but as the board worked after it was replaced.....
Obviously, this little doo-dad will be used for screening all components it will read before they go into the next set of amp boards I solder up.
Well, I have a few listening sessions with the AJ and I must say that this thing is a beauty.
Sound is full, complete and actually somewhat amazing.
Background is almost eerily silent, when a song ends it seems as if the air has been sucked out of the room and the interval before the next one begins is too long.
I've caught myself at halfway through a CD for the second time without realizing completion, then smile and let it play to the end again.
This Firstwatt deal is legit.
Sound is full, complete and actually somewhat amazing.
Background is almost eerily silent, when a song ends it seems as if the air has been sucked out of the room and the interval before the next one begins is too long.
I've caught myself at halfway through a CD for the second time without realizing completion, then smile and let it play to the end again.
This Firstwatt deal is legit.
Let me tell you a secret: Nelson Pass really knows what he's doing. REALLY knows what he's doing.
Let me tell you another secret: It would be disastrous for him to attach his name to a stinko schitt_bird product or DIY project below the GrandMaster level. Therefore he doesn't.
If you put these two facts together and reach the following conclusion: {When Nelson Pass's name is on a product or DIY project it's very VERY likely to be extremely good}
then I agree with you.
Let me tell you another secret: It would be disastrous for him to attach his name to a stinko schitt_bird product or DIY project below the GrandMaster level. Therefore he doesn't.
If you put these two facts together and reach the following conclusion: {When Nelson Pass's name is on a product or DIY project it's very VERY likely to be extremely good}
then I agree with you.
A new Aleph J was born into the DIY world today! I set the bias and dc offset as described by 6L6 at the begining of this thread and it sounds great when i drive it with my laptop. Currently Nina Simone is filling our Saturday morning with lots of smiles.
The preamp, or even my phono stage is overdiving the amp. Lots of hum/buzzing. I'm guessing i need to adjust the input bias. Looks like the 2k trimmer R8 is for this purpose but where and how much voltage am I looking for when adjusting it?
The preamp, or even my phono stage is overdiving the amp. Lots of hum/buzzing. I'm guessing i need to adjust the input bias. Looks like the 2k trimmer R8 is for this purpose but where and how much voltage am I looking for when adjusting it?
Attachments
Odd. I've driven mine with Pearl 2 phono, (tons of gain) into BA3 FE (tons more gain) with no sort of over loading problem....
Russellc
It's not the input bias pot. Leave it at it's factory position. (about 1K)
Hummmm and buzzing is something else, can you describe more how it's set up?
Hummmm and buzzing is something else, can you describe more how it's set up?
when I drive the amp with the headphone output from my laptop it sounds great. when i plug into my peamp, Emotiva bassx100 the sound at powerup is a loud buzzing. I then tried directly connecting the amp to the phono stage, a boozehound labs mm stage there is a distinct hum and the volume is very loud.