automatic censorship???
I wrote b u g g e r s (of course, without the spaces) and it seems it was automatically parsed to ******s.
Now, from Random House anabridged dictionary, I had the second entry in mind: "Informal: any object or thing", which is perfectly acceptable American English.
even the forth entry does not sound too bad:
Chiefly Bristish Slang
a despicable or contemptible person, esp. man
b an annoying or troublesome thing, situation, etc.
I know that some people in anglo-saxon countries are very sensitive to what they perceive to be inappropriate language, but I feel this censorship by automatic parsing even of words which are perfectly acceptable in large parts of the English speaking world and only mildly derogatory in others is going too far.
I wrote b u g g e r s (of course, without the spaces) and it seems it was automatically parsed to ******s.
Now, from Random House anabridged dictionary, I had the second entry in mind: "Informal: any object or thing", which is perfectly acceptable American English.
even the forth entry does not sound too bad:
Chiefly Bristish Slang
a despicable or contemptible person, esp. man
b an annoying or troublesome thing, situation, etc.
I know that some people in anglo-saxon countries are very sensitive to what they perceive to be inappropriate language, but I feel this censorship by automatic parsing even of words which are perfectly acceptable in large parts of the English speaking world and only mildly derogatory in others is going too far.
Capslocker,
little trouble to retype the message without words that upset Anglo's instead of advocating revolution.
Now-B-Off, or give us your holy words again, the diyaudio civ. way.
little trouble to retype the message without words that upset Anglo's instead of advocating revolution.
Now-B-Off, or give us your holy words again, the diyaudio civ. way.
rajeev luthra said:
Rajeev, the lamp has one thing the resistor does not, thermal inertia. So it give you more power/ current sink when it comes to music/ dynamic signal. For testing I like this, you get more dynamic headroom. The reverse is true as well, it hogs up more current when needed (a short in OP stage) than a resister which is relatively constant, because the lamp acts like a variable resistor.
PS: Now I understand why your were asking us to go to eBay, you have never been there lol.
I suggest you use the "search" to find what you want. Browsing does not always work on ebay.com because sellers sometimes put things in the wrong category. The "search" will find them all.
In the search field just put Shure +SM58
or goto this link:
http://search.ebay.com/Shure-SM58_W0QQsojsZ1QQfromZR40QQsatitleZShureQ20+SM58
Also once you go to an item you are interested in, look at the seller's feedback (usually a number next to seller ID). Avoid feedback less than 30-40 or less than 98%. Read what buyers have said about him etc.
Good luck!
K-
Capaslock,
The mje 15034/35 are some of the best drivers availible today
Rodolfo,
2N3055 is still availible here and very cheap too , its the workhorse of
the industry !!!!
Roger,
MJ15022/23 are very expensive here , but now the prices of Toshiba
devices are getting lower .
Jacco,
Actually necessity is the mother of invention , here we face another thing
which is CASH , hence if things were not availible easily and if you
would be tight on funds , then the passon in you to do something
automatically generates simple ideas and that is what we people do ,
for you all this is not required .
Thanks for finding out reg the SM58 set with receiver , if you come
across a bargin offer , please let me know .
K-Amps
Yes now you understood ,
Thanks for the Link I will try there , do some stores or suppliers from
wherehouses in the US offer attractive bargains on these ??
You know about the amp I am making , the TX is 62-0-62 , what will be
the current at PO max at 4 ohms and 2ohms , if we consider 850w at 4
ohms and dc supply at +/- 87v , will it be 850/87= 9.77A ( I have not
taken into account any losses or voltage drop ) then I have 11 devices
per rail , the current through each device will be 9.77/11= 0.88 A per
device , I want to know the voltage drop across the 0.5ohm emmiter
resistor so that I can finalise the value of the resistor going to the
protection transistor base . I think I am wrong somewhere , could you
please help ?
The mje 15034/35 are some of the best drivers availible today
Rodolfo,
2N3055 is still availible here and very cheap too , its the workhorse of
the industry !!!!
Roger,
MJ15022/23 are very expensive here , but now the prices of Toshiba
devices are getting lower .
Jacco,
Actually necessity is the mother of invention , here we face another thing
which is CASH , hence if things were not availible easily and if you
would be tight on funds , then the passon in you to do something
automatically generates simple ideas and that is what we people do ,
for you all this is not required .
Thanks for finding out reg the SM58 set with receiver , if you come
across a bargin offer , please let me know .
K-Amps
Yes now you understood ,
Thanks for the Link I will try there , do some stores or suppliers from
wherehouses in the US offer attractive bargains on these ??
You know about the amp I am making , the TX is 62-0-62 , what will be
the current at PO max at 4 ohms and 2ohms , if we consider 850w at 4
ohms and dc supply at +/- 87v , will it be 850/87= 9.77A ( I have not
taken into account any losses or voltage drop ) then I have 11 devices
per rail , the current through each device will be 9.77/11= 0.88 A per
device , I want to know the voltage drop across the 0.5ohm emmiter
resistor so that I can finalise the value of the resistor going to the
protection transistor base . I think I am wrong somewhere , could you
please help ?
I like the MJ'22/23's. I've just had good luck where I used them. Peavy had a 200watt ss guitar amp that used them at one time. Can't think of the model right now. They just take abuse really well! I've been informed that the MJ15024/25 will take more power but I haven't used them yet. The TO-3 case works for me and don't mind making room for them. Plus, they're easy for my big, fat mechanics hands to handle.
On the same kind of line; If you have been using motorola's and switched to on-semi's, what do you think of them? I can still get moto's down here. But on-semi looks like a good option.
Roger
On the same kind of line; If you have been using motorola's and switched to on-semi's, what do you think of them? I can still get moto's down here. But on-semi looks like a good option.
Roger
Re: Re: Favorite High Power Output Transistor
If you try the Mj21193/4/5/6, you will never use a MJ15022/3/4/5 again. 😉
rodolfo said:
If you try the Mj21193/4/5/6, you will never use a MJ15022/3/4/5 again. 😉
Rajeev,
I have made several amplifiers using a 1kVA toroid Per channel at 62-0-62 with +/- 87 vdc rails. On a good day, I get clipping at 400 watts 8 ohms and 650 watts into 4 ohms (a little higher if I take into account my AC mains voltage drop, but not much more) . Caps are 33000 per rail or 66000uF per channel. My amp uses no current limiting apart from fuses. I have a 2sc52000/A1493 driver driving 8 MJ21195/96 devices with 0.22 ohm E resistors. The drivers have a single 15 ohm resistance between their emitters and run very hot.
I am just wondering if you will hit 850 watts into 4 ohms. With those rails. I suspect you will need to got to +/- 96 vdc with a 1 kVA trafo .... probably more.
I have made several amplifiers using a 1kVA toroid Per channel at 62-0-62 with +/- 87 vdc rails. On a good day, I get clipping at 400 watts 8 ohms and 650 watts into 4 ohms (a little higher if I take into account my AC mains voltage drop, but not much more) . Caps are 33000 per rail or 66000uF per channel. My amp uses no current limiting apart from fuses. I have a 2sc52000/A1493 driver driving 8 MJ21195/96 devices with 0.22 ohm E resistors. The drivers have a single 15 ohm resistance between their emitters and run very hot.
I am just wondering if you will hit 850 watts into 4 ohms. With those rails. I suspect you will need to got to +/- 96 vdc with a 1 kVA trafo .... probably more.
K-Amps ,
Thanks ,
What is the max rail voltage I can go upto with 2sc52000/A1493 , also you did not tell me about the current the trs will be drawing at po max
Thanks ,
What is the max rail voltage I can go upto with 2sc52000/A1493 , also you did not tell me about the current the trs will be drawing at po max
2SA1943, not 1493.
Max Vce is 230V, i'd say keep under 100 volts.
I'd like some of that SC520000000000
Max Vce is 230V, i'd say keep under 100 volts.
I'd like some of that SC520000000000
Rajeev,
I have heard from others too, that above 85vdc, you have to use many many 5200/1943's because the SOAR declines sharply (exponentially).
Do you have the option of using the MJ21193/94? They are the 100vdc kings in today's world. I have 20 pairs or so that I can sell and ship along with the Shure mic... but if you have already bought the 5200/1943's then your call.
The 5200/193 can be used (theoratically) till +/- 115 vdc however you will need 4x number of devices in your application, i.e. at 96 vdc if you want lets say 800 watts here is what it will roughly work out to be for a 4 ohm scenario.....
At full load your rails will drop to about 80vdc so for 800 watts (56volts AC at 4 ohms) thats about 10 amps per rail.
For 10 amps at 80 vdc, you need about 24 pairs because the Ic at 160vce is about 0.2 amps based on the SOAR chart of the 1943/5200. If you settle for 600 watts at 4 ohms, 12 pairs will be fine. For 2 ohms you will need more pairs.. ;-).
Additionally I'd add more pairs to take care of non-resistive loads. Thats roughly 25% to 40% more devices.
However if you use the MJ21193/4 pair, (TO-3's) then you can do 800 watts with only 5-6 pairs !!! 😀 Because the Ic at 160vce is about 1 amp or 5 times the 5200/1943. Then add more for reactive loading and with 8-10 pairs you could probably drive 2 ohms too.
The 5200/1943 are very nice devices but they are not really meant for very high power amps, only 100-150 wpc... 200wpc tops.
K-
I have heard from others too, that above 85vdc, you have to use many many 5200/1943's because the SOAR declines sharply (exponentially).
Do you have the option of using the MJ21193/94? They are the 100vdc kings in today's world. I have 20 pairs or so that I can sell and ship along with the Shure mic... but if you have already bought the 5200/1943's then your call.
The 5200/193 can be used (theoratically) till +/- 115 vdc however you will need 4x number of devices in your application, i.e. at 96 vdc if you want lets say 800 watts here is what it will roughly work out to be for a 4 ohm scenario.....
At full load your rails will drop to about 80vdc so for 800 watts (56volts AC at 4 ohms) thats about 10 amps per rail.
For 10 amps at 80 vdc, you need about 24 pairs because the Ic at 160vce is about 0.2 amps based on the SOAR chart of the 1943/5200. If you settle for 600 watts at 4 ohms, 12 pairs will be fine. For 2 ohms you will need more pairs.. ;-).
Additionally I'd add more pairs to take care of non-resistive loads. Thats roughly 25% to 40% more devices.
However if you use the MJ21193/4 pair, (TO-3's) then you can do 800 watts with only 5-6 pairs !!! 😀 Because the Ic at 160vce is about 1 amp or 5 times the 5200/1943. Then add more for reactive loading and with 8-10 pairs you could probably drive 2 ohms too.
The 5200/1943 are very nice devices but they are not really meant for very high power amps, only 100-150 wpc... 200wpc tops.
K-
Hi K-amps,
For four pairs of transistors with +/- 80 volts supply the curves are within the SOA on the chart. It is however close to the limit above 30 volts . With inductive loads it might touch or cross the curve at some points. But that is the 'continuous' current curve.
On ac signals this must be tolerable . No doubt that if the load drops below 4 ohms it might be entering a dangerous area. But doubling the transistors ( 8 pairs) would halve the current and so it should be in a safe region for 4 ohms. Why 24 pairs ? For 1 ohm loads ?
Why do you consider the situation 160V/0.2Amps ? This situation should not occur . This is a ClassAB amp - right ?
I have tried the 5200/1943 with 90v rails, I used 5 pairs and they blew driving an 8 ohm load when they reached 300 watts (resistive). Rails had dropped to 75vdc at the time. If your rails hold steady at +/-80vdc (loaded not unloaded) 4 pairs will not survive. Rajeev wants to drive 2 ohm loads... 24 pairs was a conservative estimate for a worst case scenario. If other variables (apart from robustness and reliability) are more paramount, these numbers can be reduced, however the design objectives need to be clarified and consequences understood.
K-
PS: Commercial amps with 80vdc supplies can survive with 4 pairs of 150w devices because under load, the rails drop to 60-65vdc, and at that levels, the Ic capacity increases dramatically as opposed to 80-96vdc range.
K-
PS: Commercial amps with 80vdc supplies can survive with 4 pairs of 150w devices because under load, the rails drop to 60-65vdc, and at that levels, the Ic capacity increases dramatically as opposed to 80-96vdc range.
If Rajeev is not in favor of bridging to get this much power, why not stack the critters.
That should be good for 5 amps at 100v per double-decker.
Like Leeches.
That should be good for 5 amps at 100v per double-decker.
Like Leeches.
JensRasmussen said:
Thanks Jens,
How many do you need for 850 watts 4 ohms or 1700 watts 2 ohms? What rails etc.
Rajeev is not building an 8 ohm amplifier but 850 watts into 4 ohms. I reckon 96 vdc per rail minimum and 12 pairs.
derating...
Only gonna beat this drum just once here...
You can't use the SOA curves for 25c to 'guess' whether the transistors will survive at extremes of use...there is no way to keep the transistors cold enough at these output levels for the published curves to be useful...they need to be redrawn at the 'normal' operating temp...5 pairs will have a short and spectacular life...12 pairs might not be enough...20+ pairs is silly, better get some nicer transistors...
Stuart
Only gonna beat this drum just once here...
You can't use the SOA curves for 25c to 'guess' whether the transistors will survive at extremes of use...there is no way to keep the transistors cold enough at these output levels for the published curves to be useful...they need to be redrawn at the 'normal' operating temp...5 pairs will have a short and spectacular life...12 pairs might not be enough...20+ pairs is silly, better get some nicer transistors...
Stuart
I use the 1 second curve based at Tj = 150 degrees C.
Mind you the load line is worst case reactive load!
What is the better way of reading the SOA curve?
BTW, just last night I drew 450W into 4 ohms using 5 parallel 4281 devises at 75V non loaded rails.
\Jens
Mind you the load line is worst case reactive load!
What is the better way of reading the SOA curve?
BTW, just last night I drew 450W into 4 ohms using 5 parallel 4281 devises at 75V non loaded rails.
\Jens
K-Amps you wrote eirlear ,
Post #141
""For 2 ohm operation into 85v rails, I'd go 8 pairs of the 5200/1943's. I
would drive these with the same type i.e. 5200/1943.
This will optimize distortion for 4e operation and make 2e operation
pretty practical. Using standard drivers will let you drive 8e safely but any
reactive loads or lower impedances will strain the smaller drivers.
I have used this combinition with excellent results.
Also While using the 5200/1943 as drivers, I used a single (common)
emitter resistor of 20 ohms bypassed with a 1 uF switch-off cap across
this floating emitter resistor.""
You recomended 8pairs in output and I am using 11pairs . I have made the pcb for using the 5200/1943 and got a suitable heatsink for the same .
Post #141
""For 2 ohm operation into 85v rails, I'd go 8 pairs of the 5200/1943's. I
would drive these with the same type i.e. 5200/1943.
This will optimize distortion for 4e operation and make 2e operation
pretty practical. Using standard drivers will let you drive 8e safely but any
reactive loads or lower impedances will strain the smaller drivers.
I have used this combinition with excellent results.
Also While using the 5200/1943 as drivers, I used a single (common)
emitter resistor of 20 ohms bypassed with a 1 uF switch-off cap across
this floating emitter resistor.""
You recomended 8pairs in output and I am using 11pairs . I have made the pcb for using the 5200/1943 and got a suitable heatsink for the same .
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