As you've found out fuses should be put before the rectifier bridge if you do not have a DC protection circuit. This way it's very unlikely for the output to go DC due to output transistor failure. The most common thing to happen is a short so when this blows the fuses both rails go away, not just the one to blow first.
If you want to use that topology a regulated supply for input stage/VAS is probably a good idea but you will probably need a higher voltage extra supply for the regulators to not loose output swing and some way of making the amp clip cleanly.
The Vbe multiplier must be attached to the main heatsink or you'll have thermal stability problems, those smaller transistors are not drivers, they are more like a VAS.
If you want to use that topology a regulated supply for input stage/VAS is probably a good idea but you will probably need a higher voltage extra supply for the regulators to not loose output swing and some way of making the amp clip cleanly.
The Vbe multiplier must be attached to the main heatsink or you'll have thermal stability problems, those smaller transistors are not drivers, they are more like a VAS.
HI
If you look at the schematic what Ferenczi Posted the first one , click on the black you will see two fuse to protect the power transistors .
Those fuses only 2A and very easily ca blow up .Com pair 20A if you use double set power transistors .
It happenned with me and the 56VDC destroyed my speaker .
I agree fuse are very important at the right place even to protect your house in case something would happen .I do not talk about fuse after the rectifier.
Please click on the black posted by Ferencz and saved after magnified so you can see clearly what I'm talking about .
One more time is very stupid to protect a $3 transistor and you let your speaker get damaged which cost 100x more .After the rectifier OK to use fuse but not before the power transistor. Inside in the circuit that a bad protection .Better to buy some speaker protection than those fuses degrade the sound and if out of two one blows up your mid woofer finished .
Thanks for your advise and welcome !
Greetings
If you look at the schematic what Ferenczi Posted the first one , click on the black you will see two fuse to protect the power transistors .
Those fuses only 2A and very easily ca blow up .Com pair 20A if you use double set power transistors .
It happenned with me and the 56VDC destroyed my speaker .
I agree fuse are very important at the right place even to protect your house in case something would happen .I do not talk about fuse after the rectifier.
Please click on the black posted by Ferencz and saved after magnified so you can see clearly what I'm talking about .
One more time is very stupid to protect a $3 transistor and you let your speaker get damaged which cost 100x more .After the rectifier OK to use fuse but not before the power transistor. Inside in the circuit that a bad protection .Better to buy some speaker protection than those fuses degrade the sound and if out of two one blows up your mid woofer finished .
Thanks for your advise and welcome !
Greetings
After the rectifier/before the transistor is equivalent in this regard.
Both positions will cause DC on output if a transistor blows.
Before bridge rectifier will cause both rails to disappear if the output stage shorts.
But it's not an absolute protection, there are other ways the output can go DC than a shorted power transistor, so one should use a crowbar/relay circuit.
Both positions will cause DC on output if a transistor blows.
Before bridge rectifier will cause both rails to disappear if the output stage shorts.
But it's not an absolute protection, there are other ways the output can go DC than a shorted power transistor, so one should use a crowbar/relay circuit.
Hello
You right, but again to protect the 10A transistor with a 2A fuse and let you instead your driver blow up that very stupid .And if we double the power transistors we can talk 20A . I talking here to protect only the power transistor with a 2A fuse .
Yes we can use a fuse between the bridge in the amp PC board an good to have that .
But here I talking about protection( only) of the Darlington transistor with a 2A fuse .
When one side that fuse blows up the DC goes to the speaker coil . It happenned with me and I know what I'm talking about!!!
I know it happenned with me .
We took out those protection fuse , doubled the output transistors .My friend almost 20years using every day his amp no problem at all .And he turn on the bias 250mA .
So his amp run at least 50C degree , almost 20 years !!!
So the amp is solid like a rock with out those stupid fuses .
You may disagree but I do not like fuse at all on the PC board at all .
I have more than 20 years DIY experience .
Just take a look at the Nelson Pass amplifiers , please show me a fuse on the PC board .
Or let just talk about the Aleph X it run on high current an I put a 2A fuse before the output mosfets each side ???!! I think is a very bad idea .
Any way thanks for your comment .
I think you didn't get my point .
Please take a look the first schematic Ferencz posted , click on the black picture and you can see those 2 stupid fuse bypassed by 1uF capacitors .
You right, but again to protect the 10A transistor with a 2A fuse and let you instead your driver blow up that very stupid .And if we double the power transistors we can talk 20A . I talking here to protect only the power transistor with a 2A fuse .
Yes we can use a fuse between the bridge in the amp PC board an good to have that .
But here I talking about protection( only) of the Darlington transistor with a 2A fuse .
When one side that fuse blows up the DC goes to the speaker coil . It happenned with me and I know what I'm talking about!!!
I know it happenned with me .
We took out those protection fuse , doubled the output transistors .My friend almost 20years using every day his amp no problem at all .And he turn on the bias 250mA .
So his amp run at least 50C degree , almost 20 years !!!
So the amp is solid like a rock with out those stupid fuses .
You may disagree but I do not like fuse at all on the PC board at all .
I have more than 20 years DIY experience .
Just take a look at the Nelson Pass amplifiers , please show me a fuse on the PC board .
Or let just talk about the Aleph X it run on high current an I put a 2A fuse before the output mosfets each side ???!! I think is a very bad idea .
Any way thanks for your comment .
I think you didn't get my point .
Please take a look the first schematic Ferencz posted , click on the black picture and you can see those 2 stupid fuse bypassed by 1uF capacitors .
Hello
In one sentence even the transistor will remain OK when the fuse blow up the power from another side -DC or +DC it doesn't mater goes to the speaker coil. The transistor remain open when the -DC or +DC missing because the fuse gone . I did tested these , I removed one side the fuse and that it .
Which one do you think blow up firs a 2A fuse or 2x10A power transistor .
I think the fuse and the result the same , your speaker gone .
You save the power Darlington worth $6 and burn a Scan Speak driver ???I dont know if these only truth when we using Darlington transistos?
There are better protection that that method .
If we use fuse to protect a complete PC board or the transistors and when blows up but the transistor remain close that is correct .
But if one side the transistor get open because the fuse gone that is NO GOOD.
I tested the amp , when I took out one fuse the DC was on the output terminal .I put back the fuse and the amp was fine again .
So after we decided to take out both fuse, It is not safe at all , very high risk with out speaker protection !
Greetings
In one sentence even the transistor will remain OK when the fuse blow up the power from another side -DC or +DC it doesn't mater goes to the speaker coil. The transistor remain open when the -DC or +DC missing because the fuse gone . I did tested these , I removed one side the fuse and that it .
Which one do you think blow up firs a 2A fuse or 2x10A power transistor .
I think the fuse and the result the same , your speaker gone .
You save the power Darlington worth $6 and burn a Scan Speak driver ???I dont know if these only truth when we using Darlington transistos?
There are better protection that that method .
If we use fuse to protect a complete PC board or the transistors and when blows up but the transistor remain close that is correct .
But if one side the transistor get open because the fuse gone that is NO GOOD.
I tested the amp , when I took out one fuse the DC was on the output terminal .I put back the fuse and the amp was fine again .
So after we decided to take out both fuse, It is not safe at all , very high risk with out speaker protection !
Greetings
I think
if we want to discuss Speaker Protection we are a bit Off Topic.
I am sure there are old topics that discuss this.
Or we can start a new topic.
I agree with Protect Speakers is more important than protect transistors !
...................................................
Some good readings:
Loudspeaker Protection and Muting
Rod Elliott (ESP) Updated 22 July 2007
http://sound.westhost.com/project33.htm
Elliott makes reference to one only one source:
References:
Douglas Self - Muting Relays Electronics World, July 1999
If you want to read Douglas Self article you may try this link:
http://paid4share.net/download.php?id=4341
Somebody is sharing, currently it works ... but nobody can know for how long ...
if we want to discuss Speaker Protection we are a bit Off Topic.
I am sure there are old topics that discuss this.
Or we can start a new topic.
I agree with Protect Speakers is more important than protect transistors !
...................................................
Some good readings:
Loudspeaker Protection and Muting
Rod Elliott (ESP) Updated 22 July 2007
http://sound.westhost.com/project33.htm
Elliott makes reference to one only one source:
References:
Douglas Self - Muting Relays Electronics World, July 1999If you want to read Douglas Self article you may try this link:
http://paid4share.net/download.php?id=4341
Somebody is sharing, currently it works ... but nobody can know for how long ...
Nice amplifier..... Marshall Leach style...of course a matter of coincidence
... you have designed something even better than Leach amplifier in my point of view.
Nice one!
Leach made into the seventies...you made near 1980...... even influenced by Leach ideas you have made evoluted amplifier.
I personally do not appreciate the sonics when we have double differential....those complementary ones....because hard to match them...already not easy to match 2 NPN....now imagine ot match more 2 transistors.... and PNP, that usually have more gain..... to match all that stuff is hard.
The condensers you have will discharge very slowly because your diodes into the rails...BUT..... will produce a double thump during the power on.... i imagine..... maybe i am wrong.
Well..... you are showing your first one..... where is the last one?... because evaluating by this first one you may have a very good one now a days.... this first one is already good!
regards,
Carlos
... you have designed something even better than Leach amplifier in my point of view.
Nice one!
Leach made into the seventies...you made near 1980...... even influenced by Leach ideas you have made evoluted amplifier.
I personally do not appreciate the sonics when we have double differential....those complementary ones....because hard to match them...already not easy to match 2 NPN....now imagine ot match more 2 transistors.... and PNP, that usually have more gain..... to match all that stuff is hard.
The condensers you have will discharge very slowly because your diodes into the rails...BUT..... will produce a double thump during the power on.... i imagine..... maybe i am wrong.
Well..... you are showing your first one..... where is the last one?... because evaluating by this first one you may have a very good one now a days.... this first one is already good!
regards,
Carlos
Hello lineup
You right we should keep up the original topic , the amplifier .
There are a lot of speakers protection kit even on the forum ..
For me these amp is more important because of the simplicity of the amp the circuit and of course the great sound .
I heard something from these amp sound what I need to have it again ..
My friend has the same opinion .
I wait on Tymo if he would be so kind to design the PC board lay out so I can make my own PC board .
It not my taste to use P to P connection in a amplifier like these .
These a bit complex especially if we double the output .
Greetings
You right we should keep up the original topic , the amplifier .
There are a lot of speakers protection kit even on the forum ..
For me these amp is more important because of the simplicity of the amp the circuit and of course the great sound .
I heard something from these amp sound what I need to have it again ..
My friend has the same opinion .
I wait on Tymo if he would be so kind to design the PC board lay out so I can make my own PC board .
It not my taste to use P to P connection in a amplifier like these .
These a bit complex especially if we double the output .
Greetings
HI Carlos
It is a good solution to use a slow starter like Rode designed on his ESP site .
Yes I turn of the power and the amp still sounded for a couple minutes until the voltage went done and the sound started to get distorted . Of course depend the volume level and the bias of the amp. My fried use it in a 250mA Iq .It does bring some improvement into the sound but more heat !
The schematic originally not my own design . I did some mode in it .
It is a great sounding amp and I want these again .
Matching the Transistors are important , and you right almost impossible to match the power Darlingtons but still sounded better with 2 pair transistors than only one pair . Another advantage we can use higher V power supply .
So I only match the signal and the driver transistors !
Greetings
It is a good solution to use a slow starter like Rode designed on his ESP site .
Yes I turn of the power and the amp still sounded for a couple minutes until the voltage went done and the sound started to get distorted . Of course depend the volume level and the bias of the amp. My fried use it in a 250mA Iq .It does bring some improvement into the sound but more heat !
The schematic originally not my own design . I did some mode in it .
It is a great sounding amp and I want these again .
Matching the Transistors are important , and you right almost impossible to match the power Darlingtons but still sounded better with 2 pair transistors than only one pair . Another advantage we can use higher V power supply .
So I only match the signal and the driver transistors !
Greetings
I think we are misunderstanding each other in some way, I too believe the way they placed the fuses is pretty stupid. But moving it from there to between amplifier and power supply (one per rail) isn't any better.
If put between power supply and amp and say one output transistor shorts then one fuse will blow before the other and you will often get DC on output!
Better is having fuse only on the AC-side of the bridge rectifier. Often in commercial amps the only fuse/circuit breaker is before transformer. These are better solutions but must of course be chosen to give enough protection from fire.
If you do fuse DC rails you will need a reliable speaker protector!! It has the advantage of letting the amp continue working if one channel blows up. Not a concern for hifi but for PA I'd rather have an amp with one side still working than total silence.
If put between power supply and amp and say one output transistor shorts then one fuse will blow before the other and you will often get DC on output!
Better is having fuse only on the AC-side of the bridge rectifier. Often in commercial amps the only fuse/circuit breaker is before transformer. These are better solutions but must of course be chosen to give enough protection from fire.
If you do fuse DC rails you will need a reliable speaker protector!! It has the advantage of letting the amp continue working if one channel blows up. Not a concern for hifi but for PA I'd rather have an amp with one side still working than total silence.
Hi ferencz,
Was that Japanese schematic a commercial design? If so, who was it made by?
Thank you very much BTW.
Hi gaborbela,
The Japanese design actually looks pretty good. Those signal transistors they used are very good (classics in high end) and still available from vendors.
This little amp might make a very nice nice project. A board design would be a nice start. If the PCB is designed for normal transistors, you can still use darlingtons by shorting the E-B pads on the extra part. One board then does all. For 56V use, two outputs should be used.
Darlington transistors normally don't work as well as single parts. If the current through the driver isn't high enough, then it will not work well.
-Chris
Was that Japanese schematic a commercial design? If so, who was it made by?
Thank you very much BTW.
Hi gaborbela,
The Japanese design actually looks pretty good. Those signal transistors they used are very good (classics in high end) and still available from vendors.
This little amp might make a very nice nice project. A board design would be a nice start. If the PCB is designed for normal transistors, you can still use darlingtons by shorting the E-B pads on the extra part. One board then does all. For 56V use, two outputs should be used.
Darlington transistors normally don't work as well as single parts. If the current through the driver isn't high enough, then it will not work well.
-Chris
Hello megajoke .
Exactly , you heat the nail on the head that is what I did !!! The only fuse I used before the transformer on the AC input .That was the best solution in here .
I just didn't want to talk about because (that not the safe way is a short cut, for a little improvement ) may be someone do build the amp in the same way I do not want to be responsible .
Usually it is for safety purpose people use fuse on the PC boards or after the bridge but how I already stated I do not like fuses after the bridge rectification specially in low current biased amplifier .In another word in Class A/B amp .
In these amp we already discussed why and any another Class A/B amp the fuse on the PC board degrade the sound .
I do not want to spend $20 on a special fuse .
I know many of you disagree with these but these is my statement and I use it these way my amps .There are many different DC detectors , speakers protector , etc but that is not my cup of tea .
Please U build your amp after how think is safe and how you like it but the risk is yours who ever build these amp . Not you medajoke , anybody who build these amp or another please do not follow my bad example!
anatec you right , over 50V power supply it is better to double the output transistors .
I did built up the Darlington transistor out of two transistor (Toshiba , Motorola transistors I used ), two resistor and a diode but it the amp got somehow very slow and lifeless .
To build the Darlington out of two transistor is possible even with great result but we need to calculate to get the same speed , gain etc .
I do not have simulator .
The best for me to stick with the orig transistors . That works , rock solid even my friend biased his amp 250mA . Almost 20 years he had no problem at all ..
Another Japanese amp a bit similar to the Hiraga Class A at least the output transistors discontinued parts . I do have the original Hiraga Clone so I'm not isterested much on that . But can be a great amp to !!
I'd rather want to listening the Darlington amp than the Hiraga Class A , I do not say the Class A Hiraga not a great amp but these somehow faster much smoothness and better involving .It bring realy the musician at the front of you .
There is something in the sound what hard to explain , warm , tube like but fast with great dynamic (with 2 pair power transistors)
Like the Naim there is something in the sound that not often we can hear .
N Pass Aleph3 , it is different than the rest of the Aleps . Or one more example P Daniel Patek amplifier , there are amplifiers with better bass , better these or that but all together He still stick to his amp .
Yes I did had the opportunity to listen his system and sounds great .
Something similar in these amp is very different but in a good way .
Greetings
Exactly , you heat the nail on the head that is what I did !!! The only fuse I used before the transformer on the AC input .That was the best solution in here .
I just didn't want to talk about because (that not the safe way is a short cut, for a little improvement ) may be someone do build the amp in the same way I do not want to be responsible .
Usually it is for safety purpose people use fuse on the PC boards or after the bridge but how I already stated I do not like fuses after the bridge rectification specially in low current biased amplifier .In another word in Class A/B amp .
In these amp we already discussed why and any another Class A/B amp the fuse on the PC board degrade the sound .
I do not want to spend $20 on a special fuse .
I know many of you disagree with these but these is my statement and I use it these way my amps .There are many different DC detectors , speakers protector , etc but that is not my cup of tea .
Please U build your amp after how think is safe and how you like it but the risk is yours who ever build these amp . Not you medajoke , anybody who build these amp or another please do not follow my bad example!
anatec you right , over 50V power supply it is better to double the output transistors .
I did built up the Darlington transistor out of two transistor (Toshiba , Motorola transistors I used ), two resistor and a diode but it the amp got somehow very slow and lifeless .
To build the Darlington out of two transistor is possible even with great result but we need to calculate to get the same speed , gain etc .
I do not have simulator .
The best for me to stick with the orig transistors . That works , rock solid even my friend biased his amp 250mA . Almost 20 years he had no problem at all ..
Another Japanese amp a bit similar to the Hiraga Class A at least the output transistors discontinued parts . I do have the original Hiraga Clone so I'm not isterested much on that . But can be a great amp to !!
I'd rather want to listening the Darlington amp than the Hiraga Class A , I do not say the Class A Hiraga not a great amp but these somehow faster much smoothness and better involving .It bring realy the musician at the front of you .
There is something in the sound what hard to explain , warm , tube like but fast with great dynamic (with 2 pair power transistors)
Like the Naim there is something in the sound that not often we can hear .
N Pass Aleph3 , it is different than the rest of the Aleps . Or one more example P Daniel Patek amplifier , there are amplifiers with better bass , better these or that but all together He still stick to his amp .
Yes I did had the opportunity to listen his system and sounds great .
Something similar in these amp is very different but in a good way .
Greetings
ferencz said:
It was interesting to see this Hungarian forum topic about this amplifier.
Several pages and schematics. Thanks, ferencz
We have another diyaudio member that knows the Hungarian language,
one good friend of mine: Gyuri, member profile
He, too, can do some translations for us ....
Yes, you are right, gaborbela
This amplifier has some elements same as Hiraga Class A.
Which is also one current feedback amplifier.
Tyimo is great guy. We have discussed a lot.
But looks he is not so often around this forum now.
Tyimo profile: http://www.diyaudio.com/forums/member.php?action=getinfo&userid=4077
Tyimo was around yesterday, but his latest post was 1 month ago ( 13th Oct 2008 )
He is also from Hungary
This amplifier has some elements same as Hiraga Class A.
Which is also one current feedback amplifier.
Tyimo is great guy. We have discussed a lot.
But looks he is not so often around this forum now.
Tyimo profile: http://www.diyaudio.com/forums/member.php?action=getinfo&userid=4077
Tyimo was around yesterday, but his latest post was 1 month ago ( 13th Oct 2008 )
He is also from Hungary
Hi gaborbela,
There are ways to protect a speaker load without putting anything in line with the output. A fuse between the amplifier and speaker will certainly degrade the sound, for good technical reasons. An output relay is a better choice. Just pick the right one.
There are designs out there commercially that run the protection circuit off it's own transformer. This is referred to as a "housekeeping" transformer. When the protection circuit detects a fault, it shuts the power down to the amplifier. Possibly only the output stage is shut down. Carver amplifiers shut down the entire amp and has one of the most effective protection systems I know of.
You see, you don't have to give up sound quality to have good protection for your speakers.
If you have fuses in your DC power lines, decoupling capacitors near the outputs will help quite a bit. The voltage amp section is ideally run off a voltage regulated supply.
-Chris
There are ways to protect a speaker load without putting anything in line with the output. A fuse between the amplifier and speaker will certainly degrade the sound, for good technical reasons. An output relay is a better choice. Just pick the right one.
There are designs out there commercially that run the protection circuit off it's own transformer. This is referred to as a "housekeeping" transformer. When the protection circuit detects a fault, it shuts the power down to the amplifier. Possibly only the output stage is shut down. Carver amplifiers shut down the entire amp and has one of the most effective protection systems I know of.
You see, you don't have to give up sound quality to have good protection for your speakers.
If you have fuses in your DC power lines, decoupling capacitors near the outputs will help quite a bit. The voltage amp section is ideally run off a voltage regulated supply.
-Chris
Hello lineup
I know Tymo from the forum about two years or more .
He did promise if he will have some free time for these project will design the PC board for these amp to me .
Probably before the end of the year .
We are friends even do we newer ever met .
Hi is a great guy and has a lot of experience about different amplifiers , speakers etc .
He built a great amplifier the choke loaded SEWA . Now he is busy because he wants to improve it to the X-ed verizon .
We change mail every week a couple times .
I hope he will have some spare time to help with these project .
I can each the PC board if I have a layout but to design that not my strength.
Greetings
I know Tymo from the forum about two years or more .
He did promise if he will have some free time for these project will design the PC board for these amp to me .
Probably before the end of the year .
We are friends even do we newer ever met .
Hi is a great guy and has a lot of experience about different amplifiers , speakers etc .
He built a great amplifier the choke loaded SEWA . Now he is busy because he wants to improve it to the X-ed verizon .
We change mail every week a couple times .
I hope he will have some spare time to help with these project .
I can each the PC board if I have a layout but to design that not my strength.
Greetings
