Maybe we are just rearranging deck chairs, but it will be a much more efficient arrangement, and hopefully more comfotable chairs. I don't see anything wrong with that.
My guess is that there is only 1 king on this thread:W.M. Leach jr.
He has written a great book on audio design and is a teacher who is very well respected by his students.
I wish a had had a professor like him, mine was a jerk from Romania.
He has written a great book on audio design and is a teacher who is very well respected by his students.
I wish a had had a professor like him, mine was a jerk from Romania.
WorkingAtHome,
"Not really sure what else we could change without completely throwing out the original circuit design. "and " What else do you think should be updated "
Made the point several times that there was little to change.
If you expect to make 300 watts with the original design, at least 93V dc is required. (66-0-66 V AC 10 A) $107.30 w/o shipping at one reputable maker. Anyone want to use 100V caps on their power supply? Maybe 125V caps would be better. Purchased any lately? At 85 V you can expect 250-270 watts. A bit safer for 100V caps, eh?
Perhaps folks will re examine the verbiage posted earlier in posts #74 thru #77. High temps on devices leads to failure. But then none of you will actually try to run this beast at 200 plus watts will you? No, you will only run it at 40% max. An acceptable livingroom temperature in Holland might not be in Dallas, Texas on July 4th. "Plastic watts are not equal to metal watts. Maximum junction temperatures are different. It ususally takes 1.5X or even 2X as many plastic to be truely equal to the same part number in metal."
Is it 1.5 or is it 2?How big must the heat sink be if it turns out to be 2?
The only mention of the MJL1302(a) and MJL3281 as being preferences has been posted by jacco vermeulen. One might begin to question the agenda of the author. One need not emulate his professor.
It will be your amp to build any way you choose. But the consequences of your choices can not be avoided. And it's doubtful you can get repair service from Rotterdam or Denmark.
My goodness, what pesky questions and observations.
The NJL3281D (NPN) NJL1302D (PNP) is a worthy change that would require a "redesign" of the board in more ways than just plugging it in as a replacement. It's also plastic and new and high voltage which would seem to satisfy all those whinning about the "old, aged, soon obsolete" TO3 output transistors.
From onsemi's propaganda:
The ThermalTrak family of devices has been designed to eliminate
thermal equilibrium lag time and bias trimming in audio amplifier
applications. They can also be used in other applications as transistor die protection devices.
Features
• Thermally Matched Bias Diode
• Instant Thermal Bias Tracking
• Absolute Thermal Integrity
• High Safe Operating Area
Benefits
• Eliminates Thermal Equilibrium Lag Time and Bias Trimming
• Superior Sound Quality Through Improved Dynamic Temperature
Response
• Significantly Improved Bias Stability
• Simplified Assembly
• Reduced Labor Costs
• Reduced Component Count
• High Reliability
TO-264, 5 LEAD CASE 340AA BIPOLAR POWER
TRANSISTORS
15 A, 230 V, 200 W
Having to mount those bias diodes was always a minor annoyance.
Prosit
"Not really sure what else we could change without completely throwing out the original circuit design. "and " What else do you think should be updated "
Made the point several times that there was little to change.
If you expect to make 300 watts with the original design, at least 93V dc is required. (66-0-66 V AC 10 A) $107.30 w/o shipping at one reputable maker. Anyone want to use 100V caps on their power supply? Maybe 125V caps would be better. Purchased any lately? At 85 V you can expect 250-270 watts. A bit safer for 100V caps, eh?
Perhaps folks will re examine the verbiage posted earlier in posts #74 thru #77. High temps on devices leads to failure. But then none of you will actually try to run this beast at 200 plus watts will you? No, you will only run it at 40% max. An acceptable livingroom temperature in Holland might not be in Dallas, Texas on July 4th. "Plastic watts are not equal to metal watts. Maximum junction temperatures are different. It ususally takes 1.5X or even 2X as many plastic to be truely equal to the same part number in metal."
Is it 1.5 or is it 2?How big must the heat sink be if it turns out to be 2?
The only mention of the MJL1302(a) and MJL3281 as being preferences has been posted by jacco vermeulen. One might begin to question the agenda of the author. One need not emulate his professor.
It will be your amp to build any way you choose. But the consequences of your choices can not be avoided. And it's doubtful you can get repair service from Rotterdam or Denmark.
My goodness, what pesky questions and observations.
The NJL3281D (NPN) NJL1302D (PNP) is a worthy change that would require a "redesign" of the board in more ways than just plugging it in as a replacement. It's also plastic and new and high voltage which would seem to satisfy all those whinning about the "old, aged, soon obsolete" TO3 output transistors.
From onsemi's propaganda:
The ThermalTrak family of devices has been designed to eliminate
thermal equilibrium lag time and bias trimming in audio amplifier
applications. They can also be used in other applications as transistor die protection devices.
Features
• Thermally Matched Bias Diode
• Instant Thermal Bias Tracking
• Absolute Thermal Integrity
• High Safe Operating Area
Benefits
• Eliminates Thermal Equilibrium Lag Time and Bias Trimming
• Superior Sound Quality Through Improved Dynamic Temperature
Response
• Significantly Improved Bias Stability
• Simplified Assembly
• Reduced Labor Costs
• Reduced Component Count
• High Reliability
TO-264, 5 LEAD CASE 340AA BIPOLAR POWER
TRANSISTORS
15 A, 230 V, 200 W
Having to mount those bias diodes was always a minor annoyance.
Prosit
acenovelty said:
I refer you to postings : 34-51-59-72-73
A couple of those were yours, AceNovice !
Just for the record :
A livingroom amplifier is not a PA amplifier.
Even with full 300 watts employed the average load on an amplifier used at home is 40 % of the load of the same amplifier used for PA purposes.
Anyone that does not know this rule knows very little of amplifier design.
Rotterdam or Houston may differ 15 C/ 29 F , the difference will not kill the amplifier.
btw:
i know how hot it is in Texas, been there, have a girlfriend there.
Even considered moving there, i like the Texas caddy and ABS in Houston.
Temperature isnt lethal there, the humidity is.
I am using MT200 devices if Jens makes boards that they will fit on. Otherwise i'll use regular flatpacks, and stated as such before
"I gathered that the ones considered are the MJL1302(a) and MJL3281"
"A couple of those were yours"
Post
#34.......by djk
#51.......All perfectly suitable
#59........price comparison
#72........nope
#73........Don’t forget that the NJL3281D has the lowest SOA of all the output bjt’s onsemi makes that we have discussed as yet. It’s really an MJL3281A. by LBHajdu
Actually my choice is the Mj15003/4.
"I can do a better single sided layout of the Leach with a modern pcb designing program in 2 hours. My pc can do it in Eagle, Ultiboard2001, Orcad, or a bunch of other programs( thank you, FTP's). I'd alter the layout, certainly would not handwire the output devices, add some extra space for larger or additional components, change the TO3's for flatpacks, make the entire layout 1-dimensional, etc, etc , etc."
So why have YOU not done it? Is everything about you?
Now really, better to be AceNovice than to emulate one's professor from Romania.
BTW, Texas women know BS when they hear it, Texan girlfriends are known to shoot a guy who misrepresents the facts. Be careful out there.
Prosit
"A couple of those were yours"
Post
#34.......by djk
#51.......All perfectly suitable
#59........price comparison
#72........nope
#73........Don’t forget that the NJL3281D has the lowest SOA of all the output bjt’s onsemi makes that we have discussed as yet. It’s really an MJL3281A. by LBHajdu
Actually my choice is the Mj15003/4.
"I can do a better single sided layout of the Leach with a modern pcb designing program in 2 hours. My pc can do it in Eagle, Ultiboard2001, Orcad, or a bunch of other programs( thank you, FTP's). I'd alter the layout, certainly would not handwire the output devices, add some extra space for larger or additional components, change the TO3's for flatpacks, make the entire layout 1-dimensional, etc, etc , etc."
So why have YOU not done it? Is everything about you?
Now really, better to be AceNovice than to emulate one's professor from Romania.
BTW, Texas women know BS when they hear it, Texan girlfriends are known to shoot a guy who misrepresents the facts. Be careful out there.
Prosit
jacco vermeulen said:
I agree. He is a great guy. I had him for an analog electronics class, and a special topics class. When is he around, his door is almost always open, and he is willing to discuss anything relating to audio electronics.
As for the layout, I might work up a layout as well to see if we can generate some ideas for this project.
--
Brian
I made a parts list, as the website is a bit confusing with having to refer to both pages.
Values look alright?
I made a few substitutions for the transistors for newer devices:
mps8099 -> ztx751
mps8099 -> ztx651
mje15030 -> mje15034
mje15031 -> mje15035
mj15003 -> mjl4381a
mj15004 -> mjl4302a
I helped a couple of friends build normal leach amps with these transistors, and they seem to work fine as a straight drop-in replacement, and Dr. Leach said that they would work find also, after showing him the datasheets.
--
Brian
Values look alright?
I made a few substitutions for the transistors for newer devices:
mps8099 -> ztx751
mps8099 -> ztx651
mje15030 -> mje15034
mje15031 -> mje15035
mj15003 -> mjl4381a
mj15004 -> mjl4302a
I helped a couple of friends build normal leach amps with these transistors, and they seem to work fine as a straight drop-in replacement, and Dr. Leach said that they would work find also, after showing him the datasheets.
--
Brian
You can also use MPS651 and MPS751 from onsemi instead of ztx651 and ztx751, and they are heaps cheaper and easier to get most of the time....well in Australia anyway....
Hope this helps.
Bowdown
Brian:
Are there good substitutes for the 2N3439 and 2N5415? I
think I can still get these, but a second source would be good.
I'm thinking a layout using plastic case transistors ought to
have provisions for three output pairs for an extra margin, but
I'll go with whatever design you guys decide on...
Presently refitting my Leach amp with Fairchild Stealth
rectifiers.
--Damon (Ack! People are quoting me!)
Jacco:
I own property in Murray, Texas; everything has thorns,
especially the rattlesnakes. Last I heard there was only a
volunteer fire station left. No plans to live there; way too
remote and too bloody hot! Except in Houston, where the
humidity WILL kill you if you're not acclimated. Gah...
But with no neighbors, I can turn the volume ALL the way up!
Are there good substitutes for the 2N3439 and 2N5415? I
think I can still get these, but a second source would be good.
I'm thinking a layout using plastic case transistors ought to
have provisions for three output pairs for an extra margin, but
I'll go with whatever design you guys decide on...
Presently refitting my Leach amp with Fairchild Stealth
rectifiers.
--Damon (Ack! People are quoting me!)
Jacco:
I own property in Murray, Texas; everything has thorns,
especially the rattlesnakes. Last I heard there was only a
volunteer fire station left. No plans to live there; way too
remote and too bloody hot! Except in Houston, where the
humidity WILL kill you if you're not acclimated. Gah...
But with no neighbors, I can turn the volume ALL the way up!
While I was sleeping
This turned in a mud throwing competition.
I’m not a moderator, but I don’t really like the tone of the thread. It’s supposed to be fun, not a contest is assault.
Lighten up you guys – I’m getting a headache
EDIT: Brian, thanks for the info regarding alternative parts
\Jens
This turned in a mud throwing competition.
I’m not a moderator, but I don’t really like the tone of the thread. It’s supposed to be fun, not a contest is assault.
Lighten up you guys – I’m getting a headache
EDIT: Brian, thanks for the info regarding alternative parts
\Jens
Coulomb said:
I'll need a bigger amplifier. 😉 I have one planned
that'll do at least 500 watts/channel, maybe a kilowatt
if I can afford the power supply for it.
Heck, I can crank it to 12, if I have to paint the
number on!
--Damon, father of the BUBBA
"Our amps go to 11"
MARTY: Can I look at it?
NIGEL: No.
MARTY: Don’t look at it.
NIGEL: No, you’ve seen enough of that one. This is a top to a, you know, what we use on stage, but it’s very...very
special because if you can see...
MARTY: Yeah...
NIGEL: ...the numbers all go to eleven. Look...right across the board.MARTY: Ahh...oh, I see....
NIGEL: Eleven...eleven...eleven....
MARTY: ..and most of these amps go up to ten....
NIGEL: Exactly.
MARTY: Does that mean it’s...louder? Is it any louder?
NIGEL: Well, it’s one louder, isn’t it? It’s not ten. You see, most...most blokes, you know, will be playing at ten. You’re
on ten here...all the way up...all the way up....
MARTY: Yeah....
NIGEL: ...all the way up. You’re on ten on your guitar...where can you go from there? Where?
MARTY: I don’t know....
NIGEL: Nowhere. Exactly. What we do is if we need that extra.. push over the cliff...you know what we do?
MARTY: Put it up to eleven.
NIGEL: Eleven. Exactly. One louder.
MARTY: Why don’t you just make ten louder and make ten be the top... number... and make that a little louder?
(pause)
NIGEL: These go to eleven.
MARTY: Can I look at it?
NIGEL: No.
MARTY: Don’t look at it.
NIGEL: No, you’ve seen enough of that one. This is a top to a, you know, what we use on stage, but it’s very...very
special because if you can see...
MARTY: Yeah...
NIGEL: ...the numbers all go to eleven. Look...right across the board.MARTY: Ahh...oh, I see....
NIGEL: Eleven...eleven...eleven....
MARTY: ..and most of these amps go up to ten....
NIGEL: Exactly.
MARTY: Does that mean it’s...louder? Is it any louder?
NIGEL: Well, it’s one louder, isn’t it? It’s not ten. You see, most...most blokes, you know, will be playing at ten. You’re
on ten here...all the way up...all the way up....
MARTY: Yeah....
NIGEL: ...all the way up. You’re on ten on your guitar...where can you go from there? Where?
MARTY: I don’t know....
NIGEL: Nowhere. Exactly. What we do is if we need that extra.. push over the cliff...you know what we do?
MARTY: Put it up to eleven.
NIGEL: Eleven. Exactly. One louder.
MARTY: Why don’t you just make ten louder and make ten be the top... number... and make that a little louder?
(pause)
NIGEL: These go to eleven.
BrianGT said:
I took a look see at the data sheet of those devices.
They are 350 volt models, which means that they can handle Vpp on their own.
With these there would the option for replacing the stacked outputs with only parallel devices.
Someone mentioned the idea earlier.
Anyone ever considered the option, Brian ?
If not, maybe you could ask Professor Leach for his opinion, i remember you offered to contact him if the need arose.
I wondered if there is room on the output boards for small caps, close to the collector of each output device, something like 1000uF each.
These could add more stability for impuls power, with a 300 watt amplifier i thought that would be a nice thing, and it looks good imho.
I am not here to win a posting contest, i just would like a set of really nice, top notch quality,pcb's.
PerAnders stated at the beginning of the thread of the regular Leach that this amplifier deserves a high quality pcb.
I can do a pcb myself, if i want it fast i place the components on the board, number the pin connections and press autorouting.
There are only a few basic rules for pcb design, but making a good board layout requires much skill and experience.
Jens is a professional pcb designer, i am just a rookie, i am smart if i ask him for a set of boards.
I hope you understand that i am not going to respond to certain postings anymore, i just want a couple of boards and enjoy myself.
Damon:
last summer temperature reached low 100s here, i live at the seaside and you figure how high humidity is in a place below sealevel.
Most of my relatives are US citizens, i lived in Seattle for a year.
If you bump into someone with my last name in Washington state you bet they'll have my big nose, there are a hundred or so big noses in the Seattle area.
Texas has a long history of shipping relations with Holland, there is a vast shipping and offshore industry on the Texas south coast.
In my opinion, Texas has a lot to offer, i have met the friendliest people from Texas and South Texas is not a bad area to live.
And its a nice ride in the weekends to Carolina boat casino's.
I really do not understand why Texas is so much put down.
Seattle, thats a whole different ball game !
Re: While I was sleeping
Jens is right, and I'm now making it official.
JensRasmussen said:Lighten up you guys – I’m getting a headache
Jens is right, and I'm now making it official.
Jacco,
I plan to use the 350V devises for my extended Leach... with 5 in parallel. The rails will be arround +-70V.....
Maybe there will be less need for a new layout?
<
I wondered if there is room on the output boards for small caps, close to the collector of each output device, something like 1000uF each.
These could add more stability for impuls power, with a 300 watt amplifier i thought that would be a nice thing, and it looks good imho.
<
You need much less... I use 100nF on each collector in my extended version 😉
\Jens
I plan to use the 350V devises for my extended Leach... with 5 in parallel. The rails will be arround +-70V.....
Maybe there will be less need for a new layout?
<
I wondered if there is room on the output boards for small caps, close to the collector of each output device, something like 1000uF each.
These could add more stability for impuls power, with a 300 watt amplifier i thought that would be a nice thing, and it looks good imho.
<
You need much less... I use 100nF on each collector in my extended version 😉
\Jens
Jens,
i am commited to order two extended 10 device boards from you, as is.
If those boards can be used for the Super Leach you'll be saving me money.
What better present for a Dutch scrooge?
But i was suggesting only.
I would like to know how someone like the designer would think of the possibility.
Is it much trouble to separate gain and output powerlines on the extended Leach board Gerbers, and have a number of those made?
With separate connections i could add a regulated powersupply for the front stages without having to cut any traces.
Still4given can have full benefit of his power transformer that has dual 55 volts and 15 volts secondaries.
With separate lines people will need lower voltage output stage transformers, as i posted earlier.
Given the drop in voltage from entrance of the amplifier till the output stage it seems a waste when there is only one powerline delivering the voltage on the Super Leach.
300 watts in 8 Ohm equals around 50 volts, 15 volts lower than the 65 volts transformer the Super Leach will need for that output with only single rails, nearly 22 VDC difference.
100nF on 100Volts gives only 0.0005 joules per cap.
For a 10 mS burst 12 times 100 nF would be good for 6 watts, the way i calculated.
Is that enough ?
i am commited to order two extended 10 device boards from you, as is.
If those boards can be used for the Super Leach you'll be saving me money.
What better present for a Dutch scrooge?
But i was suggesting only.
I would like to know how someone like the designer would think of the possibility.
Is it much trouble to separate gain and output powerlines on the extended Leach board Gerbers, and have a number of those made?
With separate connections i could add a regulated powersupply for the front stages without having to cut any traces.
Still4given can have full benefit of his power transformer that has dual 55 volts and 15 volts secondaries.
With separate lines people will need lower voltage output stage transformers, as i posted earlier.
Given the drop in voltage from entrance of the amplifier till the output stage it seems a waste when there is only one powerline delivering the voltage on the Super Leach.
300 watts in 8 Ohm equals around 50 volts, 15 volts lower than the 65 volts transformer the Super Leach will need for that output with only single rails, nearly 22 VDC difference.
100nF on 100Volts gives only 0.0005 joules per cap.
For a 10 mS burst 12 times 100 nF would be good for 6 watts, the way i calculated.
Is that enough ?
Jens,
First, thank you for your willingness to take on this project. Please do not get discouraged by some of the bickering already witnessed in the thread. I think Jacco's list of requirements is reasonable.
Jens, are the above requirements achievable? I propose we base our discussion on the above requirements.
To the naysayers: Think of it as not a Leach redesign, but a new PC Board design for the Leach amp with the purpose of minimizing the external hard wiring and utilizing more modern TO-247 devices so the amplifier can be built easily by the novice as well as the experienced DIYer.
First, thank you for your willingness to take on this project. Please do not get discouraged by some of the bickering already witnessed in the thread. I think Jacco's list of requirements is reasonable.
Jens, are the above requirements achievable? I propose we base our discussion on the above requirements.
To the naysayers: Think of it as not a Leach redesign, but a new PC Board design for the Leach amp with the purpose of minimizing the external hard wiring and utilizing more modern TO-247 devices so the amplifier can be built easily by the novice as well as the experienced DIYer.
jacco vermeulen said:
Well after 1 ms the big 10000uF I have on board will take over 😉
You can ues whatever you can fit on the board, I think there are 1uF 100F film cap that can be used.
Look in the BOM on the webpage, and see the size of the box cap and it's pin distance.
BTW The extended Leach uses 105µm CU = 3 oz and the board is 2.4 mm
\Jens
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