| diysmartdeep21 |
I want to use STK amplifier for my 10 inch 120mm magnet 60 watts woofer is stk stable
I want to use the higher order crossovers and like 3rd order crossovers with STK ics
which is the best IC in STK series with 60watts output....
just give me the information regarding this....
best regards,
Sandeep |
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| richie00boy |
| You need to tell us what impedance the drive unit is as the chips will have a minimum impedance rating. |
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| diysmartdeep21 |
I need excellent quality and even it must drive heavy magnets woofers>>>>>>>
what is the model number and aslo tell me the manufacturer... |
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| Tekko |
| How about STK0060 ? 60 watt continous and 200w peak. |
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| diysmartdeep21 |
| impedence is 8 ohms |
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| richie00boy |
| Should be fine with any chip then. |
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| diysmartdeep21 |
| anybody please answer this even if u have faintest idea>>>>>>>> |
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| diysmartdeep21 |
what ive heard about STK ICS sometimes they fail and all the DC voltage is suddenly appears accross the speakers and they finally blow up !!!!!!!! the speakers!!!!! is this true?
what must be done in order to avoid this ..... give me an advice...
ive heard that if we use the speaker protection ckt then it works firne but give me some links so that ican build a simple speaker protection ckt... |
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| costiss |
| try some ti opa549 with hefty power supply.. will drive almost anything within its power limits, but has only a 36 w power rating.. sonically, its one of the finest amps you can find, provided the project is done with utmost attention to component quality and construction... |
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| Razor_Edge |
Hi sandeep,
Though I am not good at these kind of problems :rolleyes: I would certainly let you know if I learn something. On "how to get around this kind of speaker blowup problem." Meanwhile just try tweaking out with a fuse :att'n: rated slightly less the the current carrying capability of the speaker coil.
Peace
Deepak |
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| diysmartdeep21 |
| i need atleast 50 WATTS RMS audiophile quality chip amp...... and highly stable amp please tell me anyone the manufacturer of such kind of amplifier ic.... |
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| diysmartdeep21 |
| can i use this TI OPA amps in parallel to achieve more power? |
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| diysmartdeep21 |
how to calculate the speaker protection with fuse
so how to calculate the fuse value?
like for an example sometime the stability of the STK AMPS are not good in that case how can one use the protection for that...
fuse does it work? |
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| breez |
| I'm building one based on LM3886 at the moment and 50W RMS is what it should output according to my calculations :P Be sure to use bigger than 1000uF supply caps as the ripple would rise too high at high output power with the basic GC caps... |
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| diysmartdeep21 |
| can this drive 10inch 60watts rms 120 mm magnets woofer? |
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| richie00boy |
You asked for a 50 watt chip so that's what you got. It should be fine.
The woofer size and magnet is totally irrelevant to how much power. |
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| diysmartdeep21 |
breez .... well what must be the current ratings of the transformer that must be used
and what about the capcitors for filters like.. im expecting to use about 20,000 uf per rail and totally 40,000 uf total so... |
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| Jason Watts |
This is what I use.
Fuse(amps)=1.414*((Driver Power Rms)/(Driver Impedance))^(1/2) |
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| breez |
60W should be achievable at 8 ohm if you just supply enough voltage and current and take care of cooling the thing (can't go wrong with building the thing for 60W RMS continuous sine waves :p will be very reliable in casual use).
| quote: | Originally posted by diysmartdeep21
breez .... well what must be the current ratings of the transformer that must be used
and what about the capcitors for filters like.. im expecting to use about 20,000 uf per rail and totally 40,000 uf total so... |
For ~60W you'd need at least 2.75A per rail. Rail voltages need to be ~22V * 1.41 + 1.1 (diode loss) + 4 (chip needs headroom) = ~36.1V plus whatever headroom is needed for ripple. So you are going to need 38-40V rails. A 2x28VAC, 2x3A transformer would be just enough. If you want to be on the safe side you could get a transformer with higher current capability. This is for one channel.
20000uF per rail sounds good.
another edit: With very high rail voltages you need adequate cooling even with 8 ohm load. This amp will not be happy with 4 ohm load anymore with these rails, it heats like no tomorrow... |
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| Netlist |
It is my experience that fuses are too slow to protect the chip.
All STK powered amps I repaired in the past had no blown fuse but a damaged chip.
Sure you want to put a fuse in the power line and perhaps one as a speaker protector but they won't save your chip in case of a breakdown.
P.S.: On internet chatting, forums or email, the use of ALL CAPS is considered as shouting. Please turn them off.
/Hugo :) |
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| simon5 |
| Even a fastblow fuse is not fast enough? |
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| Netlist |
Maybe that could work in some cases, I can only tell from experience. Others may prove me wrong.
I wouldn't want to buy a bunch of STK's to test it though ;)
/Hugo |
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| Stuart Easson |
Hi,
Most amps whether in modules or constructed of discrete compenents have a failure mode where one or other pole of the output stage can fail shorted. If that happens the full rail voltage can be dumped onto the speaker. Either use an output cap if ultimate quality isn't needed, some sort of active speaker protector or fuses, though these are slow, and you may still damage your speaker if the overload is bad enough.
Good luck
Stuart |
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| Leolabs |
| You may try LM4780 in parallel,driving capability is much better |
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| demogorgon |
please, i beg it of you:
www.google.com
and did you search before posting?:att'n:
not trying to be a wise *** here, but i just entered the forum and saw you had made up 5 new threads in no time, when you cold have found all answers in a datacheet and on google, and collected your questions in one thread.
regards
marius |
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| diysmartdeep21 |
sorry man ive been searching these things since very long time in...
google, altavista, lycos, yahoo, rediff, etc...but coldnt find in any of this search engines
and im not boasting myself and why are u such angry....??
i didnt make any mistake...
but im totally out of time and im directly askin u people becoz u are lot more experienced than me...
Sir its better to ask in the group of experts rather than searching somewhere ...
any way thanks.....and be cool... |
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| Netlist |
Have a look here
Many of these threads have a lot of info.
/Hugo :) |
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| arasuk |
Hi smart adeep,
I am suggestting on availability in AP or kar, Stk 4191, 461,465 should be better and easily available, but also beware of FAKES there are tooooooooo!! much of them.
Thanks
Arasuk;) |
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| diysmartdeep21 |
arasuk then what about the ICS like LM 4780 are they available at Bangalore?
and what about the STK 4048 XI are they available at SP ROAD ?
did u ever try?
and also about the Toroidal Trans are they available there?
and also 10,000 uf caps? |
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| diysmartdeep21 |
so how to connect the LM 4780 in parallel?
just to connect the output in parallel? like " Y " shape?
or else how? |
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| pinkmouse |
:cop:
diysmartdeep, please respect these forums.
I have merged all your threads into one. Please do not create lots of threads on the same topic, one will do.
So far, all the questions you asked could have been answered by doing some reading of old threads here at diyAudio.
Please do not use capital letters all the time.
Thank you |
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| arasuk |
Hi smartdeep,
Well it's been long time I tried those STK Ics, & was not happy with them, I always prefer discrete BJT Amps,
Regarding 4780 I think they are not available in Bangalore as yet!!
Toroidal Trans are available,, not off the shelf,, but can get custom designed.
Yes of course any value caps are available here.
My best bet to start off the project for you is try lm3886 as these are available easily and are more stable , rugged and powerfull , you will be happy forever!!!!!
:D
Thanks
Arasuk |
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| theChris |
fast rundown:
dc offset may be corrected with done using a capacitor, relay (with circuit), or fuse.
parallel amps -- you will need equal gain on each amplifier -- mismatches lead to current flow between amps which can be very bad.
my suggestion for you is to try the lm3886 single first, should get you to the 50W range.
if you need more power, bridged lm3886 (2 chips) or 1 bridged lm4780. this works only for 8ohm loudspeakers.
netlist -- (on fuses) save the chip? or the speaker? |
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| diysmartdeep21 |
In india what is the cost of each toroidal transformer which has the ratings..... of 625VA and with 35 volts for my LM 4738... ok ive searched alot for this but couldnt find ....
just tell me where can i find this at Bangalore sp road or else tell me where can i find ready made... |
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| diysmartdeep21 |
Ive searched and im tired finally
Ive got 5 LM4780 chips and also STK amps which sounds good and as far as the stability is concerned which is best
what about the higher order crossovers can i use it with the LM and with STK s
wat about the STK 4044XI do they sound good and please tell me about the stability>>>>>>>
please guys please......... |
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| x. onasis |
You want...
Whatever the cost.....
The best....
Many can tell you the 4780 is pretty darn good. Lots of power, whatever the crossover.
The best is always subjective. (Your choices of compromises.)
Sometimes what you need is what you want, and the price you pay is what you need to learn. So do. And learn. Whatever the cost? Pay the price.
Have fun, it'll bring you good luck. |
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| carlosfm |
| quote: | Originally posted by diysmartdeep21
I need excellent quality and even it must drive heavy magnets woofers>>>>>>> |
...| quote: | Originally posted by diysmartdeep21
please guys please......... |
I don't know if you even know what you want, really.:clown: |
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| diysmartdeep21 |
thank u guys...
but as far as the higher order crossovers are concerned ive seen that chip amps blows ...so
My requirement is using the 3rd order passive crossover with the LM4780 what do u say....the still it will be stable???????
If its stable then really im very lucky...
what ...??
let me seee u reply.... |
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| diysmartdeep21 |
ok friends some of my simple questions are...
1. Is there any relation between the oversize magnet size and the type of amp ( like what ive heard that chip amp cannot drive heavy magnet woofers like (155 mm magnet size ) is it true?)
secondly can i use 3rd order crossover with the LM 4780? by making the same pcb which is given in the datasheet?
how to calculate the power ratings for the amplifier like my LM 4780 i know that the voltage ratings typical values are +/- 35 volts but what about current ratings how to calculate this... ?
please give me reply for these.... |
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| carlosfm |
| quote: | Originally posted by diysmartdeep21
My requirement is using the 3rd order passive crossover with the LM4780 what do u say....the still it will be stable??????? |
You would need an input buffer, like an op-amp, and make the filter with it.
But an OPA541 or OPA549 could work alone.
| quote: | Originally posted by diysmartdeep21
what ...?? |
Read above.
| quote: | Originally posted by diysmartdeep21
let me seee u reply.... |
Read above.
| quote: | Originally posted by diysmartdeep21
what ...?? |
Read above! :clown: |
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| diysmartdeep21 |
| but passive crossovers like 2nd or 3rd order dont work? with the LM4780?.... |
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| carlosfm |
| quote: | Originally posted by diysmartdeep21
but passive crossovers like 2nd or 3rd order dont work? with the LM4780?.... |
Give me an example of what you want to do.
Is it really a passive crossover?
So the chip doesn't have anything to do with it. |
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| diysmartdeep21 |
yeah i want to use the passive crossover like the dynaudio audience speakers they use the 3rd order crossovers so if i want to hook this LM4780 with that then what happens ...
like the other chips like stk they blow up... is it the same case with LM 4780?
another question ive been trying to get reply but nobody is replying....that is....
what are the toroidal trans ratings that must be used with this LM4780 chips...yes ive searched the datasheet i got only voltage ratings i dont know the current ratings like...
we i want to use the 35-0-35 toroidal transformer and what about the current ratings? just telll me one number which matches perfectly and will be highly stable.... |
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| richie00boy |
The passive crossover inside the speaker cabinet has nothing to do with the amp. The magnet weight and speaker size has nothing to do with the amp.
If you have heard of a chip amp blowing up it's because it was not properly implemented or it was being abused. |
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| arasuk |
Hi Sandeep!!!!
As Richie00boy!! explained , there's no relationship between big magnets and driving them!!
1. The chip lm4780 should be able to drive those drive unit you have but find its Impedence.
2. Use any order crossover that no way related to destruction of chips.
3. Remember these chips are recommended to work in +/- 35 volt DC so lessen the secondary turnings depending on the load you would like to drive.
4. And of course the current rating again depends on the load you are applying.
I strongly recommended you refer this Fantastic forum & some audio books, and then go ahead to projects.
Thanks
Arasuk |
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| diysmartdeep21 |
are there any softwares for room acoustics with 3d plots with multicolour 3d waterfall plots.. etc... i need something like that...
please give me some links if u know any of them....other than LSPCAD, WINISD etc..
ive searched the forums... i couldnt find them.. please give me some names of the free softwares.. or demo ones..... |
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| diysmartdeep21 |
Like instead of using the 500VA 22-0-22 toroidal transformer with 10,000uf of capacitor per rail and totally about 20,000uf per LM4780? which gives an equivalent of approximately 20 amperes of current at critical stages
or
using a 100VA with 22-0-22 toroidal transformer with about 20,000uf of capacitor per rail and totally about 40,000uf per LM4780 whcih give and equivalent of approx 40 amps of current at crital stages....
which one do u suggest and why?
I think second one is the best one...for performance and i want to use only 4700uf caps connected in parallel ( i know the size becomes large but it becomes much more cheaper for me... |
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| diysmartdeep21 |
ok guys thank u very much and
what about if the output get shorted? does the amp blows?
if the amps blows...
then if its in the case of 2nd order or above crossovers the output becomes shorted at the woofer then.. what even though the amp will be stable? |
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| carlosfm |
| quote: | Originally posted by diysmartdeep21
ok guys thank u very much and
what about if the output get shorted? does the amp blows?
if the amps blows...
then if its in the case of 2nd order or above crossovers the output becomes shorted at the woofer then.. what even though the amp will be stable? |
I would worry much more to make the amp stable to work at 4,000 meters under water on the Pacific ocean. |
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| breez |
| quote: | Originally posted by diysmartdeep21
20 amperes of current at critical stages |
What kind of a load are you running? 1 Ohm? With 22V secondaries you will be voltage limited long before anything near 20 amps is required. Also, the chip's current limit is much lower. |
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| richie00boy |
| Passive crossovers do not short anything out, they disconnect the specific drive unit from the driving signal. |
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| diysmartdeep21 |
| i couldnt get you i couldnt understand your language just tell me in electronics terminology please.... |
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| diysmartdeep21 |
well actually the chip current is limited to 11.5 amps right...>>> well if that is the case then can i use about *****120VA *****22-0-22 with 20,000uf per rail and total 40,000uf of capacitor for one Single LM4780 chip? so at max it may draw about 15amps is it right and note that can I USE 120VA toroidal trans with that value of capcitance?
coz i dont want to spend much on transformers.. |
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| richie00boy |
| quote: | Originally posted by diysmartdeep21
i couldnt get you i couldnt understand your language just tell me in electronics terminology please.... |
I'm not convinced you really want me to do that ;)
Think of the crossover like a variable resistor in series with the drive unit. As the signal frequency approaches the crossover frequency, the resistance of the variable resistor is increased so less power gets to the drive unit. As the crossover frequency is passed the resistor gets more and more resistive. |
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| diysmartdeep21 |
well what u say is right and its applicable with the first order crossover and
in the case of higher order crossovers the concept becomes totally opposite like it will be exactly using an variable resistor connected in parallel with the driver ...
right >>>>
now u got the idea what happens with the higher order crossovers... well the above case is with the 2nd order crossover then imagine about 6th order... that means that they have got similar ie about 3 variable resistors which are connected in parallel... so what about this case... can u explain...?? |
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| diysmartdeep21 |
HEY PLEASE ANYBODY ANSWER THIS...
well actually the chip LM4780 current is limited to 11.5 amps right...>>> well if that is the case then can i use about *****120VA *****22-0-22 with 20,000uf per rail and total 40,000uf of capacitor for one Single LM4780 chip? so at max it may draw about 15amps is it right and note that can I USE 120VA toroidal trans with that value of capcitance?
coz i dont want to spend much on transformers.. |
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| richie00boy |
| quote: | Originally posted by diysmartdeep21
well what u say is right and its applicable with the first order crossover and
in the case of higher order crossovers the concept becomes totally opposite like it will be exactly using an variable resistor connected in parallel with the driver ...
right >>>>
now u got the idea what happens with the higher order crossovers... well the above case is with the 2nd order crossover then imagine about 6th order... that means that they have got similar ie about 3 variable resistors which are connected in parallel... so what about this case... can u explain...?? |
I was trying to keep things simple :)
You are correct that there is another variable element, but this element is *after* the one mentioned above so it's diminishing resistance is 'shielded' from the amp by the other increasing resistance. |
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| grege |
hi diysmartdeep21,
[deleted]
EDIT: Looks like you went to Texas instead. :D |
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| diysmartdeep21 |
| GREGE what do u mean....i couldnt understand that... what... in texas..hmmm please give straight answers...... |
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| diysmartdeep21 |
| can I use a 120VA toroidal with 22-0-22 with about total 40,000uf ( 20,000uf per rail )... can I do this ? will the amp be stable? |
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| runebivrin |
| quote: | Originally posted by diysmartdeep21
can I use a 120VA toroidal with 22-0-22 with about total 40,000uf ( 20,000uf per rail )... can I do this ? will the amp be stable? |
Maybe it will be stable, maybe it won't. While the PSU has something to do with this, it will mainly depend on what chip you use to build it with, what components you use, how you wire it and what loudspeakers you connect it to.
2*22 volts is not really enough to get you 60 watts. Something like 2*28 is more likely to produce what you need.
Supply caps looks completely enough.
Rune
PS. Texas is a part of this forum where slightly offensive posts get moved. look here:Texas |
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| carlosfm |
| quote: | Originally posted by diysmartdeep21
can I use a 120VA toroidal with 22-0-22 with about total 40,000uf ( 20,000uf per rail )... can I do this ? will the amp be stable? |
You want to drive big woofers, so you should not compromise on the PSU.
You would be better using a 2x22v to 2x24v trafo at around 400VA.
Anyway, besides this, you are making lots of questions while the answer for most are on the datasheet, and you can also search the forum.
And I'm not Mr. Tube.:D :D :D |
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| diysmartdeep21 |
well RUNEBIVRIN well actually I wan to use the LM4780 chip so and as 22-0-22 volts are the output from the transformer then after rectification it goes to arround 31.68volts and this will be given to the chip
so I think this is much better and stable operating voltage for the LM4780 and if we use about 28-0-28 then after rectification it goes to 40.32 and with peak to peak it will go to 80.64 V which is very very close to the max voltage so ive chosen 32volts at the chip input so that it matches the requirement...
Thank you very much |
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| runebivrin |
Well, the thread started out with STK modules and 60W into 8ohms, but I suppose you've changed your mind...
Rune |
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| diysmartdeep21 |
| well i got 5 chips from natinal semic LM4780 and ive decided to work with these because of its quality...so what do u say which power supply shall I use... |
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| diysmartdeep21 |
LM 4780 are they sensitive? do they get destroyed by the static voltages of our fingers after touching the pins just like the mosfets?
Because I have touched the pins and I am doubtful about their working?LM4780 are they static sensitive devices?
Now do they work ? |
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| runebivrin |
Either work your way backwards from the desired power or forward from available transformers.
If you want 60W in 8ohms you'll need +-35V. If you use the standard single rectifier bridge, you'll need (35+1.5)/sqrt(2) = 25VAC. Of course you'll need 2*25V.
The chip is spec'd for this, so should be OK with sufficient cooling. You might want to look into paralleling the two amplifiers in the chip for better low impedance handling.
If what you have is a 2*22V 120VA transformer, by all means use it. You'll get +-30VDC, which will give you 45W output. There won't be an audible difference. If you want to run continously on full power you need one transformer per channel, as it will draw around 90W/channel then.
Rune |
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| diysmartdeep21 |
| well RUNE thank you very much according to voltage specifications its ok but what about the current requirements the current ratings of the 120VA transformer for the 22-0-22 will be about 2.72 per each rail... so can the chip work with that low current? |
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| carlosfm |
| quote: | Originally posted by diysmartdeep21
but what about the current requirements the current ratings of the 120VA transformer for the 22-0-22 will be about 2.72 per each rail... so can the chip work with that low current? |
http://www.diyaudio.com/forums/show...0557#post580557
:dodgy: |
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| richie00boy |
| Without getting into an argument about how an oversized VA transformer may sound better, 120VA will be fine for 22-0-22 one channel, just about barely adequate for two channels if you don't crank it. A good rule of thumb is transformer VA = 2x amp power. As 22-0-22 will give you 45W......... |
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