actually, for a sub amp, you should be able to use the same transistors as a UPS, since you only need about 500hz bandwidth anyway.
I was lookin around the net ...
i came across this amp ...
I think i might be able get my hands on the tip3055/2955's
Is this amp any good for a sub.
The notes say that if more transistors are paralleled to the existing output stage it can even run a 4ohm load.
How exactly is this done? does it mean that all i have to do is add another pair or two of 3055/2955's on each side?
Will the power supply need any alteration?
Can this amp be pumped up to say 200wats by adding transistors?
How good is 2n3055 transistor? Can i get one in a to220 package? or is it only made in to3?
i came across this amp ...
I think i might be able get my hands on the tip3055/2955's
Is this amp any good for a sub.
The notes say that if more transistors are paralleled to the existing output stage it can even run a 4ohm load.
How exactly is this done? does it mean that all i have to do is add another pair or two of 3055/2955's on each side?
Will the power supply need any alteration?
Can this amp be pumped up to say 200wats by adding transistors?
How good is 2n3055 transistor? Can i get one in a to220 package? or is it only made in to3?
Attachments
This is going to be my first high-power amp. I am not sure if I can try very complicated stuff. Is the A40 amp very complicated? I have seen the amp on the Pass Labs website but have not gone very deep into it. Could you guys elaborate on the quasi-comp output stage? I will do some reading up too.
Vivek
Vivek
The MJE2955/MJE3055 are versions of the 2955/3055 that are available in a TO220 package, but with lower power dissipation.
I'd say that there are far more durable and faster transistors available now for around the same price or slightly more, that it probably doesn't make sense to go with the 2955/3055 any more, especially if there is no constraint on the package type.
The best bet in India now is the original Toshiba a1943/c5200 pair. The next best bet is the original MJ15003/MJ15004, if they're available. The third best bet is the BD249C/250C, either MOSPEC or Motorola - but the PNP is rated at only 100V Vceo, and is harder to find.
I'd say that there are far more durable and faster transistors available now for around the same price or slightly more, that it probably doesn't make sense to go with the 2955/3055 any more, especially if there is no constraint on the package type.
The best bet in India now is the original Toshiba a1943/c5200 pair. The next best bet is the original MJ15003/MJ15004, if they're available. The third best bet is the BD249C/250C, either MOSPEC or Motorola - but the PNP is rated at only 100V Vceo, and is harder to find.
thanks for replying linuxguru ... so are u saying that the a1943/5200 can be directed used to replace the 3055/2955 pair in the circuit ... or are there any mods necessary?
Plus can u name any exact alternatives for the 3055/2955 pairs .. that are easily available in india ... and which are a direct fit.
Incase i wanna add 2 more pairs to the existing circuit in the output stage ... will that need any changes? by how much will i need to upgrade the power supply?
Plus can u name any exact alternatives for the 3055/2955 pairs .. that are easily available in india ... and which are a direct fit.
Incase i wanna add 2 more pairs to the existing circuit in the output stage ... will that need any changes? by how much will i need to upgrade the power supply?
i was just searchin on the net and i found that BD243/244 also similar ratings ... as the 3055/2955...
and also the bd911/912
http://www.st.com/stonline/products/literature/ds/5356/bd911.pdf
check it out please
http://www.st.com/stonline/products/literature/ds/5053/bd243c.pdf
and also the bd911/912
http://www.st.com/stonline/products/literature/ds/5356/bd911.pdf
check it out please
http://www.st.com/stonline/products/literature/ds/5053/bd243c.pdf
bd243/244 are a lower power (65W vs. 115W), lower current (8A vs. 15A) TO-220 (Versawatt) transistor pair - they're not a direct replacement for a TO-3 2955/3055 pair for high-power applications.
bd911/912 are a faster TO-220 substitute for the 2955/3055 at 90W, 15A, 3 MHz.
In the ESP circuit shown, the 2955/3055 are used as CFP output pairs with BD139/140. These are highly prone to oscillation, and the substitution of a faster output device (like the a1943/c5200) coupled with a slower driver may lead to instability/oscillations. It may need larger lag compensation caps, at the least.
bd911/912 are a faster TO-220 substitute for the 2955/3055 at 90W, 15A, 3 MHz.
In the ESP circuit shown, the 2955/3055 are used as CFP output pairs with BD139/140. These are highly prone to oscillation, and the substitution of a faster output device (like the a1943/c5200) coupled with a slower driver may lead to instability/oscillations. It may need larger lag compensation caps, at the least.
So can u suggest some other circuit .. which is easy to build .. as its only my 3rd amp ... but 1st descrete amp ...
Any circuit that is about atleast 200w into 4ohms ... and which has parts easily available in india ...
Any circuit that is about atleast 200w into 4ohms ... and which has parts easily available in india ...
Hi,
any BJT design using 2 pair of >150W devices running from 35Vac (+-50Vdc) should give 110W into 8ohm and 200W into 4ohm if properly built.
How reliable into a severe 4ohm load will depend on cooling and device SOAR.
any BJT design using 2 pair of >150W devices running from 35Vac (+-50Vdc) should give 110W into 8ohm and 200W into 4ohm if properly built.
How reliable into a severe 4ohm load will depend on cooling and device SOAR.
thnx for the reply andrew...
But as linuxguru said ... that if i use any other transistor .. there will be oscillations?
What exactly will the oscillations do in a subwoofer?
because i will be placing a filter circuit at the input?
The other thing ... can a +/-56v psu be used in the project 68 of esp .. that is the one with the tip3055/2955's?
But as linuxguru said ... that if i use any other transistor .. there will be oscillations?
What exactly will the oscillations do in a subwoofer?
because i will be placing a filter circuit at the input?
The other thing ... can a +/-56v psu be used in the project 68 of esp .. that is the one with the tip3055/2955's?
are Tips OK @ 112Vce?
What if the mains voltage goes high resulting in +-61Vdc at the supply rails. Are the Tips or any other OK @ 122Vce?
What if the mains voltage goes high resulting in +-61Vdc at the supply rails. Are the Tips or any other OK @ 122Vce?
How about Michael Chua's c200 amp?
http://www.ampslab.com/c200.htm
On page 6, he describes a quasi-complementary output stage version. You should be able to use your transistors in place of the MJ15003 with that. It uses TIP29C/30C as drivers.
http://www.ampslab.com/c200.htm
On page 6, he describes a quasi-complementary output stage version. You should be able to use your transistors in place of the MJ15003 with that. It uses TIP29C/30C as drivers.
sr2002 said:
Me, just like you, made working amps from IC chips first before ever building descrete amps. IMO it's WAY too hard to build a 200W descrete amp if you never even built a 1W amp first.
I'd recommend when learning descrete amps, is to build a small battery-powered amp first to learn how they work. Once you master the method of building one of those, you can move to bigger amps.
With batteries, If something goes wrong with the circuit, you may get some hot transistors, or dead batteries, but no fire or sparks. I used 9V (+/-4.5V 6 AA cells) on my RS electronic breadboard, and get very loud sound from 8 or 4 ohms.
Once I mastered the battery amp, then built a 50W single-supply mono amp. Learned from that, then built a 350W mono sub amp with active fan cooling, and overheat protection and more. IMO you learn as you go..
I don't know what transistors are for sale in India, since you have limited choices, I'd recommend for a 200W amp, just use the biggest & highest voltage power transistors you can get, (100V or more) don't really matter what specific transistor as long as they can handle the power. Use more transistor pairs in parallel than necessary to make the amp more reliable.
For example, I know I could have done fine with 2 or 3 pairs of outputs for a 350W amp, but I used 5 pairs instead just to be safe.
Good luck with your subwoofer amp project. Try the amp on battery first, then go for the full power after that. 😀
Meanwhile, I found some MJ15025 transistors to go with the 2N3773 ones. They were some old stock Motorola ones. Will it be okay to use the two either for the PA300 or ETI466? Now that I have good NPNs, I am even considering Quasi's Bipolar 350 amp. Opinions most welcome.
Vivek
Vivek
Eworkshop .. thanks man ... really feells good to know that someones supporting .. and understanding u ... unlike some sarcastic ... know-it-all hotshots ....
But anyways ... i found the tip3055/2599's today ...
im attaching the photo just check em out .. i mean i dunno if they are chinese or original ...
I got two pairs of the power transistors ... wich im planin to put in parallel ... so do i need to change the powe supply ... or shoould i like it to +/-35v? Because im planin to use a 4ohm sub.
What ampere rating transformer should i use?
What will the estimated power output be with two pairs of output transistors? into 4ohms ?
does the esp project 12 ... have any circuit or speaker protection?
Is there any schematic for such kind of protection ... which can be added?
What is the worst thing that can happen if i short circuit somethin?
i hope it wont blow the sub?
Cause i can go with burned transistors ... have had lots of accidents even in my chip amp projects ... Placed the capacitors with incorrect polarity ... they just bursted like a firecracker ....lol
But anyways ... i found the tip3055/2599's today ...
im attaching the photo just check em out .. i mean i dunno if they are chinese or original ...
I got two pairs of the power transistors ... wich im planin to put in parallel ... so do i need to change the powe supply ... or shoould i like it to +/-35v? Because im planin to use a 4ohm sub.
What ampere rating transformer should i use?
What will the estimated power output be with two pairs of output transistors? into 4ohms ?
does the esp project 12 ... have any circuit or speaker protection?
Is there any schematic for such kind of protection ... which can be added?
What is the worst thing that can happen if i short circuit somethin?
i hope it wont blow the sub?
Cause i can go with burned transistors ... have had lots of accidents even in my chip amp projects ... Placed the capacitors with incorrect polarity ... they just bursted like a firecracker ....lol
Attachments
I think we are going a little off-topic here. My idea of starting this thread was to discuss the PA300 and ETI466 amplifiers and output transistor substitution as I am unable to find the original output transistors. I'm sorry but I do not mean to be rude.
Cheers,
Vivek
Cheers,
Vivek
I can see vivek ... im sorry for deviating the topic ... but the only reason i barged into ur thread is because .. u seemed like a quite knowledgeble person and ur from india .. so i felt it would be convinient .. to discuss my problems with u ...
im pretty u will find ur solution man ... dont worry about it ...
Im sorry for deviating the topic again ... but ... can u please answer the questions i asked in the previous post ....
And do u think the transistors are original?
im pretty u will find ur solution man ... dont worry about it ...
Im sorry for deviating the topic again ... but ... can u please answer the questions i asked in the previous post ....
And do u think the transistors are original?
That's okay Sr2002. No hard feelings. Like you saw in one of my earlier posts, I had to cut up one transistor to find out if they are genuine ones. And they turned out to be.
Maybe you should try it too to make sure that they are good ones. It really seems like a cheap way to ensure that you have good quality transistors. I sure would not like to blow up my expensive subwoofers. Even if I had inexpensive speakers, I still would not like to see them go up in smoke. Remember, if the output transistors fail and there is no speaker protection circuitry, the DC supply voltage will appear across the speakers.
Maybe you should try it too to make sure that they are good ones. It really seems like a cheap way to ensure that you have good quality transistors. I sure would not like to blow up my expensive subwoofers. Even if I had inexpensive speakers, I still would not like to see them go up in smoke. Remember, if the output transistors fail and there is no speaker protection circuitry, the DC supply voltage will appear across the speakers.
- Status
- Not open for further replies.