Powering Up the Boards
Thank you all for your quick responses! I will try slow 6A for the line and secondary fuses and fast 4A for the rail fuses. Looks like I’m ready to power up the boards. What do you think of this procedure, which is derived from Jens’ and Leach’s web sites?
“If you are unsure of anything,” use 100 ohm 1/4 W resistors in place of the four rail fuses.
Adjust P1 on each circuit board for maximum resistance.
Connect the + from the power supply to VCC and the - to VSS.
Connect the grounds for signal in and signal out to star ground.
Power up the amp using a Variac to slowly increase the AC input voltage from 0 V to 120 V.
“If anything is wrong, the 100 ohm resistors will limit the current and smoke! If things are OK, the voltage drop across the 100 ohm resistors should be less than about 2.5 VDC.”
Turn the amp off and discharge the power supply.
Remove the 100 ohm resistors and install the install the rail fuses.
I noticed that Jens has this on his site: “The voltage with respect to ground on the basis of T1 and T6 should be 40 and +40V.” Are there other voltage measurements that should be made?
Thanks in advance for your comments.
Thank you all for your quick responses! I will try slow 6A for the line and secondary fuses and fast 4A for the rail fuses. Looks like I’m ready to power up the boards. What do you think of this procedure, which is derived from Jens’ and Leach’s web sites?
“If you are unsure of anything,” use 100 ohm 1/4 W resistors in place of the four rail fuses.
Adjust P1 on each circuit board for maximum resistance.
Connect the + from the power supply to VCC and the - to VSS.
Connect the grounds for signal in and signal out to star ground.
Power up the amp using a Variac to slowly increase the AC input voltage from 0 V to 120 V.
“If anything is wrong, the 100 ohm resistors will limit the current and smoke! If things are OK, the voltage drop across the 100 ohm resistors should be less than about 2.5 VDC.”
Turn the amp off and discharge the power supply.
Remove the 100 ohm resistors and install the install the rail fuses.
I noticed that Jens has this on his site: “The voltage with respect to ground on the basis of T1 and T6 should be 40 and +40V.” Are there other voltage measurements that should be made?
Thanks in advance for your comments.
O.K.
The boards arrived at my front porch this afternoon. I will post some picks and some comparisons next to the 10 transistor board when I shrink the files.
As usual Jens has done a really nice job. These boards are nice and thick, the silkscreen is very legible and the finish is bright and shiny. I will have to cut the extension board off as proposed earlier to fit the priority envelope. No big deal here.
Having previously paid for these boards I as usual was anxious to see the finished product. No surprise here.
I will start stuffing the mailing envelopes tonight and should have some of them mailed by Thursday.
As usual most of you followed through with prompt payment. Thank you.
If you have not yet paid please either pay or notify me so someone else may claim your boards.
Tad
The boards arrived at my front porch this afternoon. I will post some picks and some comparisons next to the 10 transistor board when I shrink the files.
As usual Jens has done a really nice job. These boards are nice and thick, the silkscreen is very legible and the finish is bright and shiny. I will have to cut the extension board off as proposed earlier to fit the priority envelope. No big deal here.
Having previously paid for these boards I as usual was anxious to see the finished product. No surprise here.
I will start stuffing the mailing envelopes tonight and should have some of them mailed by Thursday.
As usual most of you followed through with prompt payment. Thank you.
If you have not yet paid please either pay or notify me so someone else may claim your boards.
Tad
Tony,
I will let everyone know of any available boards. I only need a few myself.
I think I will bridge four of these -- always wanted 800 watts -- for a low end amp and put together a tri-amp setup. I need to figure out a suitable speaker setup for the bottom end. Hell 48 On Semi transistors should drive about anything. Ain't this a great hobby. I have this fantastic old welding machine with monster transformers. Should be a good fit.
Tad
I will let everyone know of any available boards. I only need a few myself.
I think I will bridge four of these -- always wanted 800 watts -- for a low end amp and put together a tri-amp setup. I need to figure out a suitable speaker setup for the bottom end. Hell 48 On Semi transistors should drive about anything. Ain't this a great hobby. I have this fantastic old welding machine with monster transformers. Should be a good fit.
Tad
evette,
I can not afford to just give them to you. Joking. If you will send me your email, mailing address, and full name I will include you in the list for unclaimed boards. Just click on my name to the left and you will find my email address. At this time all of the boards are spoken for though not yet all are paid for. I should know something by the middle of next week as to whether any pcb's are left over. Fair enough? There are two others also waiting for unclaimed pcb's. I only need 4 boards and most assuredly will part with the rest.
I have been studying this new 12 output board this morning and Jens has given us some huge power supply traces. There is also the feedback circuit which someone will have to explain to me the best way to implement. I would think that varying resistor values would change the feedback affect. I also think this will help to stabilize the large number of outputs.
Tad
I can not afford to just give them to you. Joking. If you will send me your email, mailing address, and full name I will include you in the list for unclaimed boards. Just click on my name to the left and you will find my email address. At this time all of the boards are spoken for though not yet all are paid for. I should know something by the middle of next week as to whether any pcb's are left over. Fair enough? There are two others also waiting for unclaimed pcb's. I only need 4 boards and most assuredly will part with the rest.
I have been studying this new 12 output board this morning and Jens has given us some huge power supply traces. There is also the feedback circuit which someone will have to explain to me the best way to implement. I would think that varying resistor values would change the feedback affect. I also think this will help to stabilize the large number of outputs.
Tad
to all group buy participants,
I have 9 pcb's which have not yet been paid for. If you received and invoice and have not yet paid, please do so. If you do not want the boards please let me know and I will give some of those waiting a chance to purchase. If not contacted by the middle of next week I will assume you do not want them. Fair enough??
I have all of the shipping cartons addressed for mailing tomorrow. The domestic -- U.S. -- shipments will leave in the morning. I will have to wait until Saturday to post the international shipments due to the extra paperwork involved. All boards will ship this week.
Thanks to all who have made this possible. Without your participation I would not have been able to acquire my own boards.
Tad
I have 9 pcb's which have not yet been paid for. If you received and invoice and have not yet paid, please do so. If you do not want the boards please let me know and I will give some of those waiting a chance to purchase. If not contacted by the middle of next week I will assume you do not want them. Fair enough??
I have all of the shipping cartons addressed for mailing tomorrow. The domestic -- U.S. -- shipments will leave in the morning. I will have to wait until Saturday to post the international shipments due to the extra paperwork involved. All boards will ship this week.
Thanks to all who have made this possible. Without your participation I would not have been able to acquire my own boards.
Tad
Regulated Power Supply
Is anyone interested in a regulated power supply for the front end?
I have been looking at adapting a circuit offered up by 'coffin' on another thread. It should work quite well as a Leach front end regulator. If there is sufficient interest I could start a new thread and document a group buy.
Is anyone interested in a regulated power supply for the front end?
I have been looking at adapting a circuit offered up by 'coffin' on another thread. It should work quite well as a Leach front end regulator. If there is sufficient interest I could start a new thread and document a group buy.
Here is the link http://www.diyaudio.com/forums/power-supplies/63844-mmini-regulator-sample-offering.html
I have already worked up a nice 2 layer board using stock parts from Digikey and Mouser. However I would want to secure coffin's blessing before making that public. Assuming that happens I would have no problem supplying the PCBs, BOM and instructions to assemble.
I have already worked up a nice 2 layer board using stock parts from Digikey and Mouser. However I would want to secure coffin's blessing before making that public. Assuming that happens I would have no problem supplying the PCBs, BOM and instructions to assemble.
Hi Tad
This thread is about the group buy for 2007.
You should used this one (2009)
Leach Amp pcb group buy interest
This thread is about the group buy for 2007.
You should used this one (2009)
Leach Amp pcb group buy interest
WJH wrote (regarding his 10-transistor build):
Hi Guys!
I've had a couple friends check out two of my boards that were "iffy", found/corrected a couple things (one rail fuse clip wasn't making good contact, one of the driver leads was shorted) and now everything tests out O.K.!
Just drilling a few more holes on the chassis, and hope to complete assembly and start listening this next week. I hope I'm not alone in completing my amp!
Anyone else out there have project updates, or photos?
Please post!
-Chas
Hi Guys!
I've had a couple friends check out two of my boards that were "iffy", found/corrected a couple things (one rail fuse clip wasn't making good contact, one of the driver leads was shorted) and now everything tests out O.K.!
Just drilling a few more holes on the chassis, and hope to complete assembly and start listening this next week. I hope I'm not alone in completing my amp!
Anyone else out there have project updates, or photos?
Please post!
-Chas
I got my regulators all soldered together and tested this morning. These are the regs Bob Ellis and Jens collaborated on. I have a 64 volt tranny feeding each of the regs and they are rock steady at 80 volts. This should be plenty for my Leach with the 70 volt rails.
I have had quite a bit of initial interest in a second group buy on these boards. It is part of a new thread for round two. If you are in need of any of these pcb's please add your interest to that thread and we can see how things will progress. If we get to 80 or 100 boards I will order them.
Hope to have further news of my amp project later this week. I have been working on it in the very early mornings before work. Not much time these days.
Tad
I have had quite a bit of initial interest in a second group buy on these boards. It is part of a new thread for round two. If you are in need of any of these pcb's please add your interest to that thread and we can see how things will progress. If we get to 80 or 100 boards I will order them.
Hope to have further news of my amp project later this week. I have been working on it in the very early mornings before work. Not much time these days.
Tad
Luke,
That is some ways off right now. I have to make sure the smoke stays in the box before I proceed. Magic smoke --- not too good.
I also am in the process of removing five of the BCxx devices and putting in the MPSA42/92 items. Just some caution. I usually have a set of spare boards for smoke and fire issues. Not this time. Have to be real careful.
I even added the proverbial 100 ohm safety resistor to the incoming power. Aren't we getting careful these days.
Now 70+ volt rails with a very stout power supply and the 80 volt frontend should get me near 300 strong watts in 8 ohms. About what I want. Never can judge how much sag I will get.
Still have the dual mono single mono issue going on. I can not make up my mind on this. I like the symetry of dual mono. What with one board on each side and such. It will just be one big monster. 4 trannys, two huge heatsinks, 32 capacitors. That is a lot for one box.
I am getting ahead of myself. Must first contain the smoke.
The second round group buy is progressing nicely. Some of you may rethink buying some extra boards. Never know when the solder bug will bite. It is after all only money. We can always earn some more.
Tad
That is some ways off right now. I have to make sure the smoke stays in the box before I proceed. Magic smoke --- not too good.
I also am in the process of removing five of the BCxx devices and putting in the MPSA42/92 items. Just some caution. I usually have a set of spare boards for smoke and fire issues. Not this time. Have to be real careful.
I even added the proverbial 100 ohm safety resistor to the incoming power. Aren't we getting careful these days.
Now 70+ volt rails with a very stout power supply and the 80 volt frontend should get me near 300 strong watts in 8 ohms. About what I want. Never can judge how much sag I will get.
Still have the dual mono single mono issue going on. I can not make up my mind on this. I like the symetry of dual mono. What with one board on each side and such. It will just be one big monster. 4 trannys, two huge heatsinks, 32 capacitors. That is a lot for one box.
I am getting ahead of myself. Must first contain the smoke.
The second round group buy is progressing nicely. Some of you may rethink buying some extra boards. Never know when the solder bug will bite. It is after all only money. We can always earn some more.
Tad