Hey wirewiggler,
When I researched solder paste to use with my Controleo3 oven, I read up on the topic on Chip Quik's website. They indicated that refrig storage was preferable with their products but not an absolute must-do. My home is temp controlled, so I just keep a tube of it in a box under my desk. 0 issues with it sitting there.
When I researched solder paste to use with my Controleo3 oven, I read up on the topic on Chip Quik's website. They indicated that refrig storage was preferable with their products but not an absolute must-do. My home is temp controlled, so I just keep a tube of it in a box under my desk. 0 issues with it sitting there.
I forgot to add the following. Although they spec 1 year for their paste, they instructed that one shouldn't necessarily discard it as it will likely still be good past the 1 year. I did happen to try this on this project with the Chip Quik tube that I had for well over a year. I squeezed out a bit from the tube, cleaned the tip, then applied it to the board. The joints looked good and well soldered to the board. YMMV, but worked for me.
Hi Andrew, I'm still making some steady progress on all these X-Altra projects. Hoping to wrap up one of them in the next couple of weeks. The Great Resignation is putting a damper on my free time. No rush, but is the preamp portion of the circuit within view? I had a hard time sourcing the 25VA xformer, but as luck would have it, DigiKey now has stock on the Amgis. Order placed! Hope all is well on your side of the pond.
Thank you for a great circuit, Andrew .
After reading through the PDF, I see that the op amp bootstrapping resistors are swapped between the schematic and the LTSpice model. In the schematic, R21 taps from the emitter of the NPN, whereas the equivalent (R2) in the model taps from the emitter of the PNP.
Question (which may be a dumb one) - does this make a difference?
EDIT: never mind, I figured it out! Derp
. After reading through the PDF, I see that the op amp bootstrapping resistors are swapped between the schematic and the LTSpice model. In the schematic, R21 taps from the emitter of the NPN, whereas the equivalent (R2) in the model taps from the emitter of the PNP.
Question (which may be a dumb one) - does this make a difference?
EDIT: never mind, I figured it out! Derp
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Well it was fun putting this together, I learned a how to solder with a hot air pencil. I wish I could say powering up went without a hitch, however it did not. C10 is the only cap not clearly marked with polarity on the circuit board. It was late and I was going to double check it in the morning you know how that turned out. Fortunately I was powering it up slowly and caught it before if blew or cooked the 1 ohm resister. I fixed it and everything came up ok however I will replace them any way. I also meant to put in a different opamp fortunately, it was a breeze to swap with the hot air pencil, after all they do call it a rework station. Now I need to build the power supply and figure out what to put it in.
Bill
Bill
Bill, that's awesome. A reflow station is on my wishlist.
Andrew, so routing psu >> baxandall >> headamp, my thinking is to use the same type relay on the Baxandall tone control, with a front panel switch to turn off the output of one of the two so that both are not on at the same time and have the tone control loaded down with both the head amp AND the amplifier at the same time. I don't know what is the accepted wisdom when routing the signal. I see that two relays shouldn't load down the psu beyond the design limit. Any thought on the wisest layout of the signal?
Andrew, so routing psu >> baxandall >> headamp, my thinking is to use the same type relay on the Baxandall tone control, with a front panel switch to turn off the output of one of the two so that both are not on at the same time and have the tone control loaded down with both the head amp AND the amplifier at the same time. I don't know what is the accepted wisdom when routing the signal. I see that two relays shouldn't load down the psu beyond the design limit. Any thought on the wisest layout of the signal?
Two relays will be fine Javier. The PSU can do 40 mA on the relay supply (12V Panasonic AGN realty’s) so that’s up to 4 relays.
The Baxandall tone control should be able to drive a power amp and headphone amp in parallel. Typical power amp Z in is 10 k and up and the headphone amp is ok with a 47 k input bias resistor or just direct coupled from the driving source (your tone control stage in this case).
(BTW, the new X-Altra Mini II boards are coming along great. Hopefully in a few weeks I can present a complete line preamp using the existing modules plus a new simplified MC/MM and a choice of discrete or op-amp based line amplifier.)
The Baxandall tone control should be able to drive a power amp and headphone amp in parallel. Typical power amp Z in is 10 k and up and the headphone amp is ok with a 47 k input bias resistor or just direct coupled from the driving source (your tone control stage in this case).
(BTW, the new X-Altra Mini II boards are coming along great. Hopefully in a few weeks I can present a complete line preamp using the existing modules plus a new simplified MC/MM and a choice of discrete or op-amp based line amplifier.)
Andrew, thanks for the detailed explanation. My thoughts tend to get a bit jumbled and I had a hunch that I was somewhere in the ballpark (the bathroom maybe?). Thanks for making it clear.
Ahhh, more temptation! I've got the chassis now so now to ponder which boards I want once you having everything ready. By next year I want to have the preamp ready with the headphone amp. I'm fortunate that I found a local shop about 3 km from my home that will silkscreen on metal. I intend to fancy this up a bit.
Ahhh, more temptation! I've got the chassis now so now to ponder which boards I want once you having everything ready. By next year I want to have the preamp ready with the headphone amp. I'm fortunate that I found a local shop about 3 km from my home that will silkscreen on metal. I intend to fancy this up a bit.
Bill what reflow station do you have? I'm looking for one but have a hard time to interpret the specs versus what I would need.
Jan
Jan,
It is a Yihua 862BD ,it was a not really expensive off Amazon but it seems to work pretty good. It also replaced my aging Weller. What I really like is I broke down and bought a Hako desolder gun I should have bought it years ago. I also used a hot plate under to work and that helps getting the solder off the syringe onto the board.
I did not comment on sound of the headphone amp because I was powering it from my bench supply and it had a bit of glare. Now powering it from the proper power supply glare is gone and nice balanced sound. Now give it a little time to run in before I put my good headphone on and listen critically. One thing the mute led turns on but does not have enough current to latch the relay.
It is a Yihua 862BD ,it was a not really expensive off Amazon but it seems to work pretty good. It also replaced my aging Weller. What I really like is I broke down and bought a Hako desolder gun I should have bought it years ago. I also used a hot plate under to work and that helps getting the solder off the syringe onto the board.
I did not comment on sound of the headphone amp because I was powering it from my bench supply and it had a bit of glare. Now powering it from the proper power supply glare is gone and nice balanced sound. Now give it a little time to run in before I put my good headphone on and listen critically. One thing the mute led turns on but does not have enough current to latch the relay.
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