don't fix it if it ain't broken.
A few words since I would like to acquire at least 4 boards.
Improve it yes, but do not fix what is not broken has been my motto.
As per Jens suggestions a few posts back (Post #267):
Changes are:
1) Better symmetry in layout.
2) Bigger rails (Now done with planes rather than tracks)
3) Feedback point moved (don�t know if this is needed but now Andrew will be happy)
4) Made better room for heat sinks on driver transistors
5) Changed small signal transistors to BC546/556
I do agree with all of them except for #3, there is no indications that this is presently an issue with so many boards and amplifiers which have been built in the past. The other drawback is that the new layout will have to be proven and this will require an extra effort for this to happen before the GB.
Therefore I would suggest to release the suggested improvements minus the output placement change. Also leave the Zobel and if the user wants to hook up a network at the speaker terminal then let him or her do it by choice.
My two cents worth... I just want to get a few boards after having missed the past GBs for different reasons.
Thanks
A few words since I would like to acquire at least 4 boards.
Improve it yes, but do not fix what is not broken has been my motto.
As per Jens suggestions a few posts back (Post #267):
Changes are:
1) Better symmetry in layout.
2) Bigger rails (Now done with planes rather than tracks)
3) Feedback point moved (don�t know if this is needed but now Andrew will be happy)
4) Made better room for heat sinks on driver transistors
5) Changed small signal transistors to BC546/556
I do agree with all of them except for #3, there is no indications that this is presently an issue with so many boards and amplifiers which have been built in the past. The other drawback is that the new layout will have to be proven and this will require an extra effort for this to happen before the GB.
Therefore I would suggest to release the suggested improvements minus the output placement change. Also leave the Zobel and if the user wants to hook up a network at the speaker terminal then let him or her do it by choice.
My two cents worth... I just want to get a few boards after having missed the past GBs for different reasons.
Thanks
Zeljko M said:...... if you guys do not make it until end of January I will have to make my own boards.
I understand that you want to design "ultimate" leach clone but 80% of builders wont be able to get all that fancy parts.
Like it or not.
Zeljko M
The Question is...just for fun...why should the guys be "stressed" by your opinion? The other group buys had to wait and so we have to wait...until the board is ready.
Fancy parts? Where do you live? You can get almost all Parts at Digikey, farnell, Rs-Components, Conrad electronics and Reichelt. They deliver world wide....i am not shure with Reichelt and Conrad.
So, my opinion is......Guys...lets order when the Board is finished. No rush...and if we reach 100 Boards....it will be most likely cheaper.
regards
Alan
I like option number 2. The components on the board with the short feedback trace.
Essentially the major schematic change is the addition of the feedback loop. (The layout change is board mechanics) How much feedback will you expect to need in this new layout. Do YOU EXPECT to encounter problems with this design necessitating the testing of a prototype board.
How does this differ from the original Leach feedback scheme.
I have not done any in depth electronic testing of my amp. (do not know how) but the original design sounds quite good without the feedback. Thanks Tad
Essentially the major schematic change is the addition of the feedback loop. (The layout change is board mechanics) How much feedback will you expect to need in this new layout. Do YOU EXPECT to encounter problems with this design necessitating the testing of a prototype board.
How does this differ from the original Leach feedback scheme.
I have not done any in depth electronic testing of my amp. (do not know how) but the original design sounds quite good without the feedback. Thanks Tad
DVBjunky said:
The Answer is...just for fun...
No body should be "stressed", I was trying to push GB a little.
Now I am still at sea, but when I get home I'll have to solder something. If you like to wait, or look at waiting as some kind of fore play - OK!
RS is very expensive in Croatia, I have not tried farnell and Conrad.
Can you find good price for output transistors and make small "GB"? I'm in!
In order to obtain a decent price on the boards for the last GB we had to wait 30 days for delivery. I believe it was worth it to get the boards at 13.00 each.
The best price I have found on the output devices is Avnet -- thanks Bob Ellis -- though at this time there is quite a long lead time on delivery.
Totally overwhelmed by the fact that everyone on the Wiki actually paid and took delivery of the boards --- very unusual in todays world -- I would be willing to do a group buy on OP devices and power supply caps. Let me know. I also benefit greatly from these purchases. Tad
The best price I have found on the output devices is Avnet -- thanks Bob Ellis -- though at this time there is quite a long lead time on delivery.
Totally overwhelmed by the fact that everyone on the Wiki actually paid and took delivery of the boards --- very unusual in todays world -- I would be willing to do a group buy on OP devices and power supply caps. Let me know. I also benefit greatly from these purchases. Tad
peranders said:
From Leach's web site:
R50 and C25 mount on the loudspeaker output binding posts. On the first amplifier I built, I had these on the circuit board where they caused violent oscillations because the current through R50 and C25 generated positive feedback when it flowed through the circuit board signal ground lead. When the oscillations occurred, the heat sinks would get very hot. Moving R50 and C25 to the loudspeaker output binding posts solved this problem.
Zeljko
In the previous GB of the Jen's 10 transistor layout Advanced Circuits allowed me to purchase 120 boards with a first time customer discount of 500.00. I passed the total savings on to the group. We paid roughly 13.00 U.S. for each pcb.
I doubt that the previous deal will extent to the current amp layout which we are at this time trying to iron out.
The total price for the pcb's will not be known until the gerber files are downloaded and quoted. As Bob Ellis stated earlier in this thread boards of this size usually cost about 20.00.
So if you are interested in any of this place your name on the Wiki for boards when they are made available. I hope this cleared that up. Tad
On another note. Jen's I have full confidence in your ability to work out the details of this new design. In fact -- in my opinion --you can create something totally new and unique and we can give that a try. This current design I have running does not even get warm at extended full volume. Push the design to 250 watts. I would like that. I am having lots of fun here. Tad again
In the previous GB of the Jen's 10 transistor layout Advanced Circuits allowed me to purchase 120 boards with a first time customer discount of 500.00. I passed the total savings on to the group. We paid roughly 13.00 U.S. for each pcb.
I doubt that the previous deal will extent to the current amp layout which we are at this time trying to iron out.
The total price for the pcb's will not be known until the gerber files are downloaded and quoted. As Bob Ellis stated earlier in this thread boards of this size usually cost about 20.00.
So if you are interested in any of this place your name on the Wiki for boards when they are made available. I hope this cleared that up. Tad
On another note. Jen's I have full confidence in your ability to work out the details of this new design. In fact -- in my opinion --you can create something totally new and unique and we can give that a try. This current design I have running does not even get warm at extended full volume. Push the design to 250 watts. I would like that. I am having lots of fun here. Tad again