How to Pass a little time ...cont

Holy cow! I don't think I understood how big those heatsinks were until this picture. Inspiring work.

 

if you fancy a drive up to the brew city this weekend I can hook them up and give you a listen - am home alone saturday

 

Would absolutely love to, but I promised that I would help my girlfriend take her mother car shopping. Already put it off twice...

 

Guilt is a powerful force

I scavanged a pot off another preamp and wired up the NuTube buffer - did not expect that !! It sounds incredible.



(not pretty but functional)

could be the combo PASS SIT with NuTube but it seems to work well - I wonder if it would be too much of a good thing with decent speakers.

..dB

 

Spent a glorious day in DIY heaven

My PASS SIT amp closed up but not yet finished - needs finished - initial plan was to paint it but this beast sits at about 50 deg C - most paint will not tolerate that, might explore high temp paints. Anodizing is an option but I am not pulling the whole thing apart - so would have to just be the panels.




The trigger to start the amp - this is Ti Kan's trigger from AMBLABs



Back panel



Internal rail leds for my peace of mind - I hate not knowing that everything is powered as it should be and this way I can chill




and because i had to be around to watch the multimeters while I cooked the amp for a few hours today

Norwood daughter board for the M2X



Muses volume control for the B1 nutube pre






The SIT amp is sounding pretty damned amazing. It ran for about 8 hours straight while I teased the offset into place - finally settled at less than 10mV per channel. Going to run through this exercise with sacrificial speakers for a few more days then plug it into the main rig for a listen.

..dB

 

Head to an autoparts store and grab some engine enamel. I have had very good luck with Rust-Oleum specifically and it gives a good finish.

 

now just to wait for some decent weather - the last time I sprayed down in the basement, I messed with the HEPA filters and was not a popular guy , aside from the fact that new filters cost significantly more than a can of spraypaint

Hooked it up to the Maggies today - been "working" listening to music - keep getting distracted and finding myself sucked into the music - a very good place to be. This amp reminds me of my original stacker and has the same spatial realization as the stacker power that started me off on this entire adventure.



just scary good, totally not practical though, the amp weighs a ton, doesn't fit into the rack and near boils at 50deg C (too hot to touch for more than a few seconds) , but what sound!!

..dB

 

don't paint radiators. Only anodizing or natural color. dye strongly affects the cooling.

The paint layer is equivalent to thermal protection. Paint will add you 10-15 degrees of heat on transistors.

 

I was planning on leaving them alone, mostly because it would be a real pain to disassemble them . thanks for the warning though as it hadn't occurred to me.

..dB

 

Technology of electrochemical dyeing of aluminum simple. But smelly.


An alternative to electrochemistry. Paints, but the coating is not resistant.

 

that is all I need , add smell to noise and my wife will truly divorce me

I used to etch my own PCBs and the mess of the ferric chloride used to drive her mad - i see that you have a "mad scientist" lab, very envious

 

My wife, a former police officer, thinks " a man without a hobby is a potential criminal"

 

Congrats on the radiator dBel

 

Lucky we were having - 50 deg Temps for a while

 

Had been struggling a little to get the amp to bias up appropriately and ( smarter folk than me ) finally figured out that the Vgs of the SIT was too far out of range for the design of this amp. I had measured the Vgs at 19V when I was originally screening components but as the Vgs is dependent on Drain voltage which are higher than anticipated - my amp sits at 25.4 rails - the Avel-Lindberg must have poorly spec'd secondaries so unloaded the AC is closer to 20V and rectified takes it up close to 26VDC unloaded. ( the amp is designed with an anticipated 22.4V on the rails )

This meant that the SITs were passing close to 3A with the additional voltage and the bias adjustment didn't work as the Vgs of the SITs and FETs were too close .

Added a patch using a small IRF520 mosfet to drop the voltage to the SIT down to 20V , this drops the Vgs of the SIT and brings the numbers into alignment for the bias circuit to work as designed,



Ran the amp for 5 hours and it is rock solid, still sounding great - finally at a point where I don't need to worry about the amp and can sit back and enjoy

..dB

 

in the spirit of idle hands and passing time



I wanted the Lineaum ribbon from the optimus LX-5 and had always been curious about Monsoon planars ( which I may drop into the OBs too )

but for kicks I thought what would happen if......

surprisingly not too shabby !

..dB

 

At first glance it looked like you added a nice space heater to your workshop.

 

really good sounding space heaters - for a very messy workspace

 

Building yet another PASS amp - have posted most of this at DIYA but wanted to share with all you good people

This one came about by chance and an itch which always seems to occur when things get incrementally busier at work. It must have something to do with stress management but when things get obnoxiously busy at work, I find myself driven to build "stuff" and as it happens I found a board for the Mini Aleph on DIYA ( to complement the F3, F4, F5 boards that are in my drawer already !!!! ) But as all the the latter are complex and require serious heatsinking, I figured a "simple" Aleph build would be easier to accomplish.

psu

It turned out the transformer that I had labelled 24V in my parts bin was not 12-0-12 but 24-0-24 which put an initial spanner in the works. I had a 35-0-35 transformer in the bin too so I decided to try my hand at unwinding the secondary and clipping it in 1/2 to give me a theoretical 17.5 vAC

I can assure anyone who has this transient mad idea, stop and buy a transformer - winding those secondaries tight and aligned was a major PIA and I ended up with serious repetitive strain injury in my wrists. BUT the project was a success and I ended up with 19-0-19 when measured.

The chassis was a swap meet find - a repurposed Tandberg case that I cleaned up.





back panel



FETs mounted





Ready to be tested



Wiring added



Test phase

- initial bias at stock settings for power up



Fully biased to 1.2A



I let it cook for several hours with repeated bias setting until it finally settled in - put it into the bench test system to make sure it generated music and it sounded promising.


Moved it to my desk which is where it will ultimately rest for near field listening while I work at home.



I can pick up a very low level hum in the system which I will address once I figure out the front plate , in the mean time, I will continue to enjoy what appears to be another winning design from NP. The sound is effortless with great detail and transients are excellent. Bass does not disappoint. It replaces another NP designed ADCOM 5300. I can hear differences but not "night and day" - I really think those ADCOM units are a steal if you bump up their bias points - I picked up the ADCOM for $200 and would never be able to build its replacement for the cost.


..dB

 

I actually have some mini-Aleph boards I picked up pretty cheap from chipamp.com when it was still operational. I'm debating if I should do the 10w version or full 30w.