I got the XA252 SET fired up on the bench. My crappy test speakers are singing!!!
25+25V donuts get me 31.8V rails.
One channel I max out the bias current pot at ~1.7A The bias pot is clicking at max.
The other channel I max out at about ~1.6A.
The heatsinks on the Bose chassis can take a lot more... I'm tempted to go up to 1.8A, close it all up and see how hot it gets.
ZM- should I drop in a ~1K2 in position R28 to get a little more bias?
Tomorrow I'll let it cook a few hours.
Once I get bias dialed in just right I'ts on to the faceplate. This will take some creativity to get right. 2 analog VU meters + backlighting, 2 LED VU Meters that I'll replace, and a logo light.
25+25V donuts get me 31.8V rails.
One channel I max out the bias current pot at ~1.7A The bias pot is clicking at max.
The other channel I max out at about ~1.6A.
The heatsinks on the Bose chassis can take a lot more... I'm tempted to go up to 1.8A, close it all up and see how hot it gets.
ZM- should I drop in a ~1K2 in position R28 to get a little more bias?
Tomorrow I'll let it cook a few hours.
Once I get bias dialed in just right I'ts on to the faceplate. This will take some creativity to get right. 2 analog VU meters + backlighting, 2 LED VU Meters that I'll replace, and a logo light.
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I'm scared
that bench is too clean .......
I like my coffee black and my bench clean 🤣
1k2 swap (well 2k2 parallel with 2k7) worked to get the bias up.
I’m cooking it on the bench now to see what the heatsinks feel like after an hour or so.
I’m cooking it on the bench now to see what the heatsinks feel like after an hour or so.
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I moved the amp from the bench to my Tannoys last night and listened for a while. I left it on all night, and now I've had about 90 minutes of music and some coffee.
Spooky. 3D. Detailed. Fast. BASS. Dead quiet. Simply beautiful.
I'll have to try this on my Hartsfields next. I'll wait until I have finished the bling VU meters on the front panel.
Superb job ZM!! And of course, blame Pa!
Spooky. 3D. Detailed. Fast. BASS. Dead quiet. Simply beautiful.
I'll have to try this on my Hartsfields next. I'll wait until I have finished the bling VU meters on the front panel.
Superb job ZM!! And of course, blame Pa!
It just gets better the more you listen 🙂 Congratulations
The front panel is the next phase of this project. Parts are inbound now.
It will have a logo at the top left with backlight. I will add a LED meter at the open hole on the left. And I will backlight the big analog meters and make them dance, too.
For now, audio only.
It will have a logo at the top left with backlight. I will add a LED meter at the open hole on the left. And I will backlight the big analog meters and make them dance, too.
For now, audio only.
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Smoked glass.
Here’s my idea for the logo light box. I’m going to go for LED instead of incandescent bulbs. Probably blue.
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I used the original Bose plexi/lexan as the cutting & drilling template. Mine came out "good enough", I think. The cuts will be behind the metal plate, which is behind the smoked glass. So my sins will be twice hidden.
At first I looked online for someone who does custom cut/print on lexan. Honestly didn't look too hard after I found a price of $50+tax+ship to cut one small piece. Printing not included. So it looks like more DIY Time.
My solution - I bought 2 sheets 12" x 12" x 1/8" of white translucent plastic on Amazon and printer transparency sheets.
I used a jigsaw with "ultra clean" blade on the plastic, then tiny and successively bigger drill bits for the holes.
I played around with fonts printed up some "logo" text on the transparency sheets and cut it to fit over the lexan. The print isn't perfect, but I'm sure it will be fine hiding behind smoked glass. I tried the current Formula 1 font, which looked cool. But I think it will look dated quicky. The font you see is "Optician Sans", which looks like a classic eye chart.
I'll repeat this cutting and drilling process on the LED VU Meter plastic.
The transparency of my lexan is different from the original Bose. Let's what happens with 2023 LED's or LED bayonet bulbs vs. 1970's incandescent.
At first I looked online for someone who does custom cut/print on lexan. Honestly didn't look too hard after I found a price of $50+tax+ship to cut one small piece. Printing not included. So it looks like more DIY Time.
My solution - I bought 2 sheets 12" x 12" x 1/8" of white translucent plastic on Amazon and printer transparency sheets.
I used a jigsaw with "ultra clean" blade on the plastic, then tiny and successively bigger drill bits for the holes.
I played around with fonts printed up some "logo" text on the transparency sheets and cut it to fit over the lexan. The print isn't perfect, but I'm sure it will be fine hiding behind smoked glass. I tried the current Formula 1 font, which looked cool. But I think it will look dated quicky. The font you see is "Optician Sans", which looks like a classic eye chart.
I'll repeat this cutting and drilling process on the LED VU Meter plastic.
The transparency of my lexan is different from the original Bose. Let's what happens with 2023 LED's or LED bayonet bulbs vs. 1970's incandescent.
yeah
Bubba Bob is in possession of Holy Set of pcbs
zero specimen - all prototyping finished wit those
in fact, he initially got very next set, but he was successful in BigBadaBoom
#452, I've told him then - in future, you'll get populated and tested and pre-set channel modules
he's my Bubba, so why not
Bubba Bob is in possession of Holy Set of pcbs
zero specimen - all prototyping finished wit those
in fact, he initially got very next set, but he was successful in BigBadaBoom
#452, I've told him then - in future, you'll get populated and tested and pre-set channel modules
he's my Bubba, so why not
I suppose if the new piece has its own bulb, you could probably change the resistor feeding the bulb to dim it a little bit. Looks pretty good. I'm really excited to see it wrapped off. I bet you are too.
As flocchini said, The sound will get better and better. 🙂
Progress Porn Post. A window of opportunity for a rare two days without life getting in the way of pleasant pastimes arose and I did the carpe diem bit. Built the XA252 and Scryer kits that had wended their way through Ancient Batsch (twice), Viking land and finally to this rock a few months back. Fun.
Sadly, completion is in the hands of customs as they have the chassis' and toroids. So we wait....
Sadly, completion is in the hands of customs as they have the chassis' and toroids. So we wait....
