The real draw of the TIP35/6 is the usefully high hFE at 25A. More than the C5200. That's why you find these things in a lot of mid-wattage 2-ohm car amps, where you are operating off 25-30V rails. Of course, universal availability isn't hurting anything.
The SOA isn't THAT bad. Full power to 30V, the same as may vintage TO-3 types. Most "audio" types start their s/b limits at 50V, and I see them being used well beyond SOA ratings all the time in store-bought equipment.
The SOA isn't THAT bad. Full power to 30V, the same as may vintage TO-3 types. Most "audio" types start their s/b limits at 50V, and I see them being used well beyond SOA ratings all the time in store-bought equipment.
Amplifier was waiting so long but finally I have assembled it.
Operating parameters with one pair of TIP35C/TIP36C:
-supply voltage: 2x42V@36V at load,
-max voltage with minimal distortion (3.8Ohm resistive load): 19V,
-output power: 95W,
-dissipated power: about 90W.
Amp has worked at this ratings about 10min and I'm happy, that transistors didn't explode.
Operating parameters with one pair of TIP35C/TIP36C:
-supply voltage: 2x42V@36V at load,
-max voltage with minimal distortion (3.8Ohm resistive load): 19V,
-output power: 95W,
-dissipated power: about 90W.
Amp has worked at this ratings about 10min and I'm happy, that transistors didn't explode.
Ian got it right. The TIP35/36 really aren't well suited to Hi-Fi service. Besides the Hfe Vs Ic non linearity, they're really slow. The upside is that they're cheap at $1.28, but NJW0281/NJW0302 are $1.13 and $0.93 on ONSemi's site and they'd make a way better amplifier. If you have some really cheap TIP35/36 from surplus, go for that to learn, but there are better choices for a final amplifier. Use a couple or three in parallel so that you stay on the flat part of the Ic/Hfe curve.
A resistor test load is NOT a stressful test for an amplifier.
An 8ohms capable amplifier must be able to drive an 8r0 for ever, if you can keep the heatsink cool enough.
The same 8ohms capable amplifier should be able to drive a 4r0 test load for some minutes, again taking steps to keep the sink cool enough.
My test for adequacy of Current Output is to drive a 2r6 resistor for a few seconds to nearly the same output voltage as the 8r0 test load.
i.e. 2r6 @ ~-1dBV relative to 8r0.
I have built four quite different amplifiers that can achieve better than -0.6dBV into 4r0 relative to 8r0.
An 8ohms capable amplifier must be able to drive an 8r0 for ever, if you can keep the heatsink cool enough.
The same 8ohms capable amplifier should be able to drive a 4r0 test load for some minutes, again taking steps to keep the sink cool enough.
My test for adequacy of Current Output is to drive a 2r6 resistor for a few seconds to nearly the same output voltage as the 8r0 test load.
i.e. 2r6 @ ~-1dBV relative to 8r0.
I have built four quite different amplifiers that can achieve better than -0.6dBV into 4r0 relative to 8r0.
You've got right, but during normal listening amp never works at max continuous power.
Probably I'd make test with 2Ohm resistive load and result will be known, this transistors are so cheap and good for experiments.
At such a small supply voltage (36~37V at load) in my opinion 100W at one pair isn't difficult to reach, but may be a bit dangerous...
My earlier amp (only 2x35V with no load) was built using one pair of transistors similar to 2N3055, short circuit for a few seconds didn't do anything with them.
Probably I'd make test with 2Ohm resistive load and result will be known, this transistors are so cheap and good for experiments.
At such a small supply voltage (36~37V at load) in my opinion 100W at one pair isn't difficult to reach, but may be a bit dangerous...
My earlier amp (only 2x35V with no load) was built using one pair of transistors similar to 2N3055, short circuit for a few seconds didn't do anything with them.
One pair of these at +/-37V with 4 ohms is less "dangerous" than one pair of C5200 type being used at +/-70V in a typical store-bought reciever. You know, one that says "8 ohms minimum load" right on the back of it. Or three pair of C5200 on +/-67V driving 2 ohms (BTW, it's called an RMX1450 and they don't blow up that often).
The usual power prediction I use is:
Maximum output power into a reactive speaker is approximately the total 25°C device capability divided by 5 to 6.
For a one pair stage of 115W devices, this comes out at [115+115] / 5 or approximately 46W, 27.1Vpk.
This would be the target for an 8ohms capable amplifier.
Into 4r0 expect 70W to 80W, 23.8Vpk to 25Vpk, into 2r6 expect 90W to 110W, 21.6Vpk to 24Vpk.
If the amp can't meet these dummy load targets, then the amplifier+PSU is not a "very good" 8ohms capable amplifier.
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I have a stock of TIP35C/36C. I would like to build an amp with them using a +/- 35V supply. Could you share your schematic?
If you want to save the pain of blowing TIP35/36 on 35V rails, be sure to use a cheap, undersized EI transformer. The sag of the rails under load (which most constructors don't have the test equipment to see or measure) will save them from an early fate. Either that or use only 25-30V rails.
In my experience, people using these transistors at 35V or more (yes, me too) are already using small transformers - It's only "stiff" power supplies that can be a problem.
In my experience, people using these transistors at 35V or more (yes, me too) are already using small transformers - It's only "stiff" power supplies that can be a problem.
From practical experience making musical instrument amps, which are always used loud for many hours, one pair TIP35/36 is safe for +/-47V rails and 8 ohm speaker loads.
Use a good heatsink and let air flow around it (i.e. not inside a closed cabinet) and 2 pairs are fine for same nominal rails , 4 ohms load, larger heatsinks.
Why "nominal" rails?:
Real World PSU typically drop 15/20% under load.
And that´s normal.
Use a good heatsink and let air flow around it (i.e. not inside a closed cabinet) and 2 pairs are fine for same nominal rails , 4 ohms load, larger heatsinks.
Why "nominal" rails?:
Real World PSU typically drop 15/20% under load.
And that´s normal.
I disagree.
A 35-0-35Vac transformer gives around +-50Vdc in a biased ClassAB amplifier.
The nominal voltage will remain within 1V, even when producing 10W of output power into a 8r0 load. How often does your amplifier get to with -10dB of maximum power? How long does the output stay at that high level?
By the time the amp is at half maximum power (-3dB ref max), I would expect the PSU voltage to have dropped by 2Vdc to 3Vdc, i.e to around +-47.5Vdc. This is "only" a 5% drop for half maximum power.
I would expect a reasonable PSU to drop no more than 6 or 7Vdc (to around ~+-43Vdc) when delivering a continuous output at the maximum rating.
That 7V is still "only" 14% and the amplifier should not be producing "maximum power" for longer than a few tens of micro seconds. During that transient the PSU is basically delivering power by slightly depleting the supply rail capacitances.
One should NEVER be able to measure supply rails that drop by 15% to 20% while reproducing audio signals.
RE tip35/36C From st micro.
These transistors are amazing, at 25amp cont and 50amp peak your fuse will blow before the ST.
I use them in most repair and reworks.
Be sure to by the same batch number on both for audio perfection/perfect match.
if in doubt take a good dmm and measure the B/C B/E to ensure they are a perfect match.
They put toshiba 5198/1941 and most of the sankens to shame.
The toshiba 1943 and 5200 can also be substituted with the ST's.
If you purchase from a reputable company the chances of them being rip offs are minimal.
When it comes to TO3 packs i only use the tranis from the quad 909, a beast which i had the Pleasure of testing to for a few weeks after rebuild, at 25% drive it drove my 300wrms at some serious db ratings.
The police were at the door within 15 minutes to "Please don't rearrange the "neighbors ornaments".
The 909 used MJ15003's, 20a, 140v, 250w, 6 per channel.
The 5200/1943 are for the budget price point importers, they dont have much overhead and pop easily even with the best protection.
44CT357
These transistors are amazing, at 25amp cont and 50amp peak your fuse will blow before the ST.
I use them in most repair and reworks.
Be sure to by the same batch number on both for audio perfection/perfect match.
if in doubt take a good dmm and measure the B/C B/E to ensure they are a perfect match.
They put toshiba 5198/1941 and most of the sankens to shame.
The toshiba 1943 and 5200 can also be substituted with the ST's.
If you purchase from a reputable company the chances of them being rip offs are minimal.
When it comes to TO3 packs i only use the tranis from the quad 909, a beast which i had the Pleasure of testing to for a few weeks after rebuild, at 25% drive it drove my 300wrms at some serious db ratings.
The police were at the door within 15 minutes to "Please don't rearrange the "neighbors ornaments".
The 909 used MJ15003's, 20a, 140v, 250w, 6 per channel.
The 5200/1943 are for the budget price point importers, they dont have much overhead and pop easily even with the best protection.
44CT357
Had to check because I found it unbelievable and you are right, they don't.
Useless crappy datasheet if it omits such an important parameter.
I make Guitar amps since forever (1969) and I remember early on I had discarded TIP35/36 because of the horrible SOA rating (considering its otherwise high voltage and current capability)
There must be a reason *nobody* (I'm talking commercial makers) uses them, except Gallien Krueger ... who use 4 of them for +/-40V rails and 100W RMS into 4 ohms.
So I kept searching and found On Semi datasheet ... OMG!!!
http://www.onsemi.com/pub_link/Collateral/TIP35A-D.PDF
Dissipation curves bend sharply down between 32 and 35V !!!!!!!!!!!!!
They are good candidates only for low voltage (+36V single supply) very high current transformer output PA amps, which are meant to be emergency powered by 2 x 12V car batteries in series ( think Indian made Ahuja Amplifiers) .
But for conventional amps ... keep searching.
FWIW smaller and cheaper TIP142/147 have in practice same or better SOA, go figure, so *they* became an Industry standard.
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