Terry,
Take your DC volt meter and connect the red wire to E of T16 and the black to E of T23.
Remove signal from input (and speakers just in case).
Turn on amp.
Using R52 and R46 as 0R47 calculate 0.06A *(R52+R46) = 56 mV
This gives 60mA in every pair of output transistors.
Let the amp heat for an hour and adjust P1 until the voltage reads 56mV.
Keep the amp turned on and watch the voltage. Adjust if necessary.
Adjust for optimal sound and make sure heat is not a problem.
I think that is it...... 🙂
BTW typical DC losses will be VCC*I*6 = 55V*0.06A*6=20W
\Jens
Take your DC volt meter and connect the red wire to E of T16 and the black to E of T23.
Remove signal from input (and speakers just in case).
Turn on amp.
Using R52 and R46 as 0R47 calculate 0.06A *(R52+R46) = 56 mV
This gives 60mA in every pair of output transistors.
Let the amp heat for an hour and adjust P1 until the voltage reads 56mV.
Keep the amp turned on and watch the voltage. Adjust if necessary.
Adjust for optimal sound and make sure heat is not a problem.
I think that is it...... 🙂
BTW typical DC losses will be VCC*I*6 = 55V*0.06A*6=20W
\Jens
Hi Still4given,
this applies to all three amps you have already finished (not the Aleph).
they are all push pull output stage.
they are all emitter follower.
they all have emitter resistor to output.
they are all set up by measuring the voltage across the emitter resistor.
measure the Re voltage.
measure or read the value of Re.
Calculate the emitter current(amps) Iq=Vre / Re.
For an output stage that has one pair of devices the total current through the pair Iq=Vre/Re.
for two pair Iq=2*Vre/Re. and for 3 pair Iq=2*Vre/Re.
Go and write this into your reference book (data page) and then insert the appropriate data for each channel of each of your amplifiers. For future reference you should also add in all the reference voltages to the schematics for each design. Just in case one develops a fault.
Once you have the quiescent voltages use the same formula to calculate all the quiescent currents and add them to the schematic.
You should by then be starting to recognise some patterns and similarities and from this start to appreciate the differences in the front ends of the amps. From which some understanding of the electronics will follow.
I see Jens just beat me to it.
this applies to all three amps you have already finished (not the Aleph).
they are all push pull output stage.
they are all emitter follower.
they all have emitter resistor to output.
they are all set up by measuring the voltage across the emitter resistor.
measure the Re voltage.
measure or read the value of Re.
Calculate the emitter current(amps) Iq=Vre / Re.
For an output stage that has one pair of devices the total current through the pair Iq=Vre/Re.
for two pair Iq=2*Vre/Re. and for 3 pair Iq=2*Vre/Re.
Go and write this into your reference book (data page) and then insert the appropriate data for each channel of each of your amplifiers. For future reference you should also add in all the reference voltages to the schematics for each design. Just in case one develops a fault.
Once you have the quiescent voltages use the same formula to calculate all the quiescent currents and add them to the schematic.
You should by then be starting to recognise some patterns and similarities and from this start to appreciate the differences in the front ends of the amps. From which some understanding of the electronics will follow.
I see Jens just beat me to it.
Hi Andrew,
That sounds like very good advice. If I could only find the time. I will try and fit that in somewhere. 😀
It has been a while since I set the bias on the Leach. I guess I should check it to see where it is at. I believe I set it at 58.4V using the method that Jens just suggested. It will be interesting to see if it is still there. I remember that raising it did seem to smooth out the highs some.
Blessings, Terry
That sounds like very good advice. If I could only find the time. I will try and fit that in somewhere. 😀
It has been a while since I set the bias on the Leach. I guess I should check it to see where it is at. I believe I set it at 58.4V using the method that Jens just suggested. It will be interesting to see if it is still there. I remember that raising it did seem to smooth out the highs some.
Blessings, Terry
Loboone said:
I began my 1st project, a BOSOZ, using the Pass schematic and parts list, then, like you, wondered about upgrading all the parts to maximize performance. Not knowing what I was really doing, but reading up on resistors and capacitors and silver wire, made me mentally think up all kinds of crazy confiurations.
In the end, I just used standard parts (extra uf on the PS), silver wire and solen caps, and after the almost 2 years of work, was just happy that the thing worked.
Having made a Krell clone and a chipamp, and a few other things now, and having blown up numerous components, making lots of mistakes, I have decided to forgo the craziness.
For many of us, including me, just getting the amp to work is a major accomplishment. I'm going to tackle this Leach after an A-X, and then I'll only be 2 years behind Terry, assuming for the normal build schedule.
JensRasmussen said:
Hi Jens,
Do you think that 60mA is optimal or just a starting point? I think someone said that higher bias on these is not necessarily better. How high can I safely go do you think? I just wan to smooth out the highs a little.
Thanks, Terry
60 mA is a starting point IMO.....
I don't remember what my setting is, but mine is still a bit on the bright side on some tracks... I guess it is also a matter of how well the CD you listen to is produced.
\Jens 🙂
I don't remember what my setting is, but mine is still a bit on the bright side on some tracks... I guess it is also a matter of how well the CD you listen to is produced.
\Jens 🙂
JensRasmussen said:
OK then. If yours is on the bright side too, I won't worry about it. I can always EQ. You can always get rid of highs. If they are not there is is very difficult to add them.
Blessings, Terry
SPICE version of leach amp?
Jens, i was referred to this thread by a fellow member. He said that you put the leach amp into pspice and I was just wondering if you would be kind enough to share your work with a fellow audio diy'er. I wanted to use SPICE to probe different parts of the amp to learn how it works. Thanks in advance!
Jon
Jens, i was referred to this thread by a fellow member. He said that you put the leach amp into pspice and I was just wondering if you would be kind enough to share your work with a fellow audio diy'er. I wanted to use SPICE to probe different parts of the amp to learn how it works. Thanks in advance!
Jon
"OK then. If yours is on the bright side too, I won't worry about it"
Sounds like it's a trait. Could be related to the Leach Design itself, biassing, or the cramped board layout. Which begs the question: On what basis was this very cramped layout done?
Cheers,
Greg😀
Sounds like it's a trait. Could be related to the Leach Design itself, biassing, or the cramped board layout. Which begs the question: On what basis was this very cramped layout done?
Cheers,
Greg😀
Ha I never professed to design a great website. I don't have the time. I was never into 'special effects'. I'm down to earth and so is my website. It gets the message across.
But apparently you build pretty amps that defy the laws of physics - I'm intrigued.
Cheers,
Greg
But apparently you build pretty amps that defy the laws of physics - I'm intrigued.
Cheers,
Greg
jens
BTW typical DC losses will be VCC*I*6 = 55V*0.06A*6=20W
------------------------------------
Hi Jens i dont understand your calculation very well what is 6
for (is it for devices?) how many devices is your amp using
good to talk to you jens, share with us the magic stuff, thnks
btw Dr Leach awesome guy ive been to his webpages and he
has some excellent material there
cheers
BTW typical DC losses will be VCC*I*6 = 55V*0.06A*6=20W
------------------------------------
Hi Jens i dont understand your calculation very well what is 6
for (is it for devices?) how many devices is your amp using
good to talk to you jens, share with us the magic stuff, thnks
btw Dr Leach awesome guy ive been to his webpages and he
has some excellent material there
cheers
Who ever "professed to design a great PCB" ? Who ever said the person who designed this PCB had alot of time? What I can tell you is that the designer has done something constructive, which is more than I can say for you.
IMO you are not down to earth - and seem to need a new hat. Perhaps visit this store - they may have one that fits.
You seem too have enough time to mouth off about other people's work, but not quite enough to offer any solutions.
My recommendation is for you to save up the time from a couple of these mouth off sessions, as they are not constructive anyway, and sue it constructivly. Either rework your site into something intelligable or provide us with a better PCB design for the Leach which is not simply a rehash of this one.
IMO you are not down to earth - and seem to need a new hat. Perhaps visit this store - they may have one that fits.
You seem too have enough time to mouth off about other people's work, but not quite enough to offer any solutions.
My recommendation is for you to save up the time from a couple of these mouth off sessions, as they are not constructive anyway, and sue it constructivly. Either rework your site into something intelligable or provide us with a better PCB design for the Leach which is not simply a rehash of this one.
Sweetie,
Grow up - learn to take advice without smarting. You want a great board layout. Can you afford it
Just because you don't know how to doesn't mean it's not important to the performance of the final result. You put in so much effort then have a 'she'll be right' approach to layout or consider it only superficially.
IT MATTERS. Deal with it.
Greg
Grow up - learn to take advice without smarting. You want a great board layout. Can you afford it
Just because you don't know how to doesn't mean it's not important to the performance of the final result. You put in so much effort then have a 'she'll be right' approach to layout or consider it only superficially.
IT MATTERS. Deal with it.
Greg
The layout of PCB's for minimal interaction is an art - ask an RF designer! I do this as a part of the design of my products because I have honed this skill over many years of practical product design.
I'm telling you it's important so you're eyes and minds are open but it's a part of my skill-set I'm not willing to give away. You can learn the same way I did - by experience and with an open mind. No wideband amplifier is impervious to it's environment.
Buying designer endorsed PCBs is one way. Ignoring interactions is no way.
Cheers,
Greg
I'm telling you it's important so you're eyes and minds are open but it's a part of my skill-set I'm not willing to give away. You can learn the same way I did - by experience and with an open mind. No wideband amplifier is impervious to it's environment.
Buying designer endorsed PCBs is one way. Ignoring interactions is no way.
Cheers,
Greg
Hello all,
I'll see what I can find when I get home 🙂
I would like to emphasize that the amp I build is only bright one some tracks, I have yet to determine if it is the amp (speakers vs amp) or the track. This weekend I will test the track with my reference amp and see if there is any difference. I have not listened to the track with my ref amp as I have had the amp in stock since we moved.
BTW the layout is not cramped at all, there is tons of space left.... I could have used SMT parts in some places but did not to make it easier to build by hand.
What laws are we talking about here? - Please explain further share all of your GURO powers please
I’m just an average Joe that was stupid enough to post some stuff I messed about with in my spare time for all of you to comment… I’m no guro on linear LF amp stuff, but I work with high performance switch mode power supply stuff and I know how important the PCB layout is.
That would be the DC losses (VCC=55V) from the DC current (60mA) in the output stage (6 transistors). You need to add losses from actually playing music
Help us by beeing the GURO you claim to be - put your money where your mouth is!
I this the marketing section of your company speaking?
I did change the input filter of the amp compared to the original, maybe it's worth trying out the original config also.... More info after the weekend.
\Jens
frckid said:
I'll see what I can find when I get home 🙂
amplifierguru said:
I would like to emphasize that the amp I build is only bright one some tracks, I have yet to determine if it is the amp (speakers vs amp) or the track. This weekend I will test the track with my reference amp and see if there is any difference. I have not listened to the track with my ref amp as I have had the amp in stock since we moved.
BTW the layout is not cramped at all, there is tons of space left.... I could have used SMT parts in some places but did not to make it easier to build by hand.
amplifierguru said:
What laws are we talking about here? - Please explain further share all of your GURO powers please
I’m just an average Joe that was stupid enough to post some stuff I messed about with in my spare time for all of you to comment… I’m no guro on linear LF amp stuff, but I work with high performance switch mode power supply stuff and I know how important the PCB layout is.
mastertech said:
That would be the DC losses (VCC=55V) from the DC current (60mA) in the output stage (6 transistors). You need to add losses from actually playing music
amplifierguru said:Sweetie,
Grow up - learn to take advice without smarting. You want a great board layout. Can you afford it
Just because you don't know how to doesn't mean it's not important to the performance of the final result. You put in so much effort then have a 'she'll be right' approach to layout or consider it only superficially.
IT MATTERS. Deal with it.
Greg
Help us by beeing the GURO you claim to be - put your money where your mouth is!
amplifierguru said:
I this the marketing section of your company speaking?
I did change the input filter of the amp compared to the original, maybe it's worth trying out the original config also.... More info after the weekend.
\Jens
"ask an RF designer"
I did not know that we were designing the Leach as an RF amplifier
I suggest that if your only purpose for being here is to punt your own products without contributing technically – then rather leave. It is COWARDLY for you to criticize vaguely without specific examples and technical discussion. It is this sort of commentary that is dimming the lights of diyaudio.
I just had to laugh at the mutually exclusive "No wideband amplifier is impervious to it's environment" and "with an open mind". I certainly wouldn't want somebody with this sort of intellect designing my audio equipment.
I did not know that we were designing the Leach as an RF amplifier
I suggest that if your only purpose for being here is to punt your own products without contributing technically – then rather leave. It is COWARDLY for you to criticize vaguely without specific examples and technical discussion. It is this sort of commentary that is dimming the lights of diyaudio.
I just had to laugh at the mutually exclusive "No wideband amplifier is impervious to it's environment" and "with an open mind". I certainly wouldn't want somebody with this sort of intellect designing my audio equipment.
Hi Sweetie,
I really only offerred my kit products to give a FINE example of what could be achieved and make it available at minimal cost to DIYers. I have given this forum a great deal in a short time despite the troglydite's smarting. I don't need to do it - but I have - for the education of those interested in my field of endeavour and who want to best their system! Unfortunately, in this country, there are no positions that pay state wages to produce 'free to air' product designs so I have to retrieve something for mine!
If you're complaining about my miniscule prices for the trouble of dealing with scurrilous commercial vendors then I'm terribly sorry! If you want me out of here because I challenge your belief regime I'm here forever! There are people out there who want better audio not blinkered belief.
Only trying to help.
Cheers,
Greg
I really only offerred my kit products to give a FINE example of what could be achieved and make it available at minimal cost to DIYers. I have given this forum a great deal in a short time despite the troglydite's smarting. I don't need to do it - but I have - for the education of those interested in my field of endeavour and who want to best their system! Unfortunately, in this country, there are no positions that pay state wages to produce 'free to air' product designs so I have to retrieve something for mine!
If you're complaining about my miniscule prices for the trouble of dealing with scurrilous commercial vendors then I'm terribly sorry! If you want me out of here because I challenge your belief regime I'm here forever! There are people out there who want better audio not blinkered belief.
Only trying to help.
Cheers,
Greg
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