TIP33/TIP34 for output devices 1st SS amp.

Status
Not open for further replies.
Jump to Latest
bOTL

bOTL

Member
Joined 2010
botlaudio.com
#1
TIP33c/TIP34c for output devices 1st SS amp.

I know these are old devices but I was given 50 of each would like to build a SS power amp does anybody have a simple design that sounds good. Have built many tube projects. Any help would be great.

Happy New Year
 
Last edited:
#2
Yes, shame to waste any power transistor. You may be aware though, that basic TIP33/34 transistors are low voltage types (Vceo 40V) and +/- 24V power supply rails may be the absolute limit you could use with them in a normal push-pull complementary amplifier design. That would limit power from an AB class amplifier to about 25W/8R. However, there are any amount of audio amplifier designs discussed in this forum that could be adapted to operate with anywhere from 15-50V supplies.

The practical question though, is whether you can make your own PCBs or whether you need someone to supply them and this limits the choices. In your position, I would use a simple design on strip board or buy a pair of PCBs for a simple, popular design that suited broadly similar parts like TIP3055/TIP2955, on-line. Then fit your own parts and power supply to suit the lower voltage.
 
#4
Ian Finch said:
Yes, shame to waste any power transistor. You may be aware though, that basic TIP33/34 transistors are low voltage types (Vceo 40V) and +/- 24V power supply rails may be the absolute limit you could use with them in a normal push-pull complementary amplifier design. That would limit power from an AB class amplifier to about 25W/8R. However, there are any amount of audio amplifier designs discussed in this forum that could be adapted to operate with anywhere from 15-50V supplies.

The practical question though, is whether you can make your own PCBs or whether you need someone to supply them and this limits the choices. In your position, I would use a simple design on strip board or buy a pair of PCBs for a simple, popular design that suited broadly similar parts like TIP3055/TIP2955, on-line. Then fit your own parts and power supply to suit the lower voltage.
Click to expand...

Actual they are tip33c/34c
 
#5
#6
Id say look to build a 30W amplifier, say +/- 25V supply voltages. There's plenty of simple design using TIP2955/TIP3055 for example that you could use with the TIP33C/TIP34C. Dont bother with anything too elaborate 🙂
 
#7
bOTL said:
Actual they are tip33c/34c
Click to expand...
That does allow you to use slightly higher supply rails but it doesn't change the Safe Operating Area of the transistors. At 30V Vce for example, the current limit is down to 2-3A and with realistic temperature derating, make that 2A max. I'm happy to be corrected but I guesstimate 30W/8R to be a safe max. power limit for audio. http://www.mouser.com/ds/2/54/tip33-307823.pdf

There is always the option of using low impedance speakers or building twice the number of amplifiers and bridging them for more power but I don't find it worth the hassle or necessary for home use, at least.
 
#8
bOTL said:
Actual they are tip33c/34c
Click to expand...
Anything a TIP31/32 can do, that Kurozz used, a TIP33c/34c can do.
If you want something more powerful that a 100v Vceo rated transistor can stand, try this 5 transistor design: http://www.diyaudio.com/forums/solid-state/236256-retro-amp-50w-single-supply-20.html
I think it is designed for +50 v rail but I'm using 70.
Use heatsinks on the drivers & VAS transistor above 30v.
Your TIP33c/34c are slow, 3 mhz so no use buying the rare and hard to find fast transistors Mr Slavkovik specs for VAS & drivers. TIP41c/42c will do. 3 mhz transistors won't reproduce the highest of tinkly bells properly, but then your TIP33c/34c won't either with the same Ft. If you're driving 4 ohm speakers, just double up on the output transistors and emitter resistors, the TIP41c/42c drivers will drive them with a heat sink.
For a picture of a point to point build, look at post 212 of that thread. There are masks for etch it yourself boards in earlier posts. The TIP33c/34c will have to mount on a separate heat sink with flying wires, they are not TO3 like the artwork specifies. The way I built my AX6 as shown in the picture.
The rail voltage is 1.4* the specified transformer voltage, in case you didn't know. Minus two diode drop, 1.2 v. Buy caps specified higher than that voltage, too, instead of the 63 v ones Mr Slavkovik specifies.
I find the cheapest output tranistor heat sinks are from salvage. Salvage PCAT power supplies, salvage televisions (LED ones are really good) salvage VFD motor drives. They are quite expensive from the major suppliers. heatsinkusa in the vendor forum below has good USA prices but I don't know if he marks up his shipping costs or not like many tiny suppliers do. (UPS stores will kick back I suspect).
transformers are best from apexjr down in vendor forum or some importer in NJ I can't remember right now. Kurozz first amp would work on a doorbell transformer from the hardware store. I'm using 6.5 amp 70v for my AX6 out of my salvage dynaco ST120 chassis. Other parts come best from newark (NJ) mouser (TX) or digikey (MN). Don't forget the mica washer kits and heat sink compound. newark sells inexpensive mica kits (10 for $2.50) for TO3P with the plastic ferrules included that keep the screw from shorting. The flying TO220 heat sinks for the TIP41c/42c don't need insulators, and are pretty cheap from any of the above suppliers. Or I made some out of window frame with hole drilled in it, you'll see in the picture. A numbered drill index assortment is handy, mine has the # drill for the US number machine screws stamped right on it. #4 screws will fit all the heat sinks and transistors. I like elastic stop nuts because they don't come unscrewed. I get screws & nuts in packs of 50 or 100 stainless ones from mcmaster.com I also get the NEMA CE (garolite) blank canvas 1/16" board from them. Mcmaster and newark freight is under $10 usually unless you buy a 12x24" board, more like $13.
Have fun.
 
Last edited:
#9
As you've got plenty of these really old-school power devices, I'd recommend you to use a design of suitable age, e.g from the RCA Power Transistor Applications Manual, page 194. For 4 ohms load, use four pairs of your transistors, one pair as drivers, three pairs as power devices. Use a 35-0-35 V transformer and get a non-load rail voltage of +/- 50 V. You may obtain about 150 watts of output power from each channel.

Best regards!
 
#10
iirc telefunken et al. used this darlington's in some designs long time ago......
....have seen this in the hifi gear of a friend.
typically used with 50V....60V single supply / 2x25......30V dual supply and 8 ohm speakers........
 
#14
Kay Pirinha said:
As you've got plenty of these really old-school power devices, I'd recommend you to use a design of suitable age, e.g from the RCA Power Transistor Applications Manual, page 194. For 4 ohms load, use four pairs of your transistors, one pair as drivers, three pairs as power devices. Use a 35-0-35 V transformer and get a non-load rail voltage of +/- 50 V. You may obtain about 150 watts of output power from each channel.

Best regards!
Click to expand...
Thanks for the input it looks promising.

John C.
 
#17
Botl,
I have built amplifers using TIP31/32 and TIP41/42. One of them is attached - I have included schematics, PCB layout and silk. If you want the ALTIUM files I can shoot them through to you.

This is NOT the worlds best amplifier... the aim was something very (very) small and discrete.

To be honest, I can't remember the power supply I ran this off, it will not have been great - as the SOAR of the TIP31/32 and TIP41/42 is good, but they are not the sort of devices that you will use in an arc welder...

A few tings to note:
- The output needs to have an inductor in parallel to the "6R8 resistor". This is made by winding some 1mm copper wire around the resistor before loading it. Altium doesn't like "made up" things, so I just made a note to self to do that while building it.

I have specced a 2sc2682 VAS, anything VAS like and fast wiull be fine. BF469/70 would be a good alternative, choose your preference. A MJE340 would work, but not be great.

A few more comments:
- The tiny layout results in compromises in layout. The ground is not great, and
- You need two wire links. (The shame of it)
- The PCB is only 2.1 by 2.7 inches (55 by 69mm) this suited me in the intended application.
- If I recall you can expect no more than about 20 odd watts from the TIP31/32. Don't kid yourself you can make a monstr amp with these devices, the voltage limitations are pretty real.

I used these in test equipment - so modest power and "average" layout was ok.

View attachment TIP41-2 Amplifier.pdf

View attachment Top Layer.pdf

View attachment Silkscreen.pdf

View attachment Bottom Layer.pdf
 
#19
Kay - are you sure? You might want to do a fact check on this one.

The main failure mode of a trimpot is to go open circuit. In the case that the trimmer is:
- Between Base and Collector, then if the resistor goes open, the VBE multiplier is biased off, and all the VAS current goes through the output devices base circuit - i.e. over biases the output stage.

- Between the base and emitter, then if the resistor goes open, the VBE multiplier is biased hard on, causing the output stage to be under biased.
 
#20
You're right. Anyway, I've never seen an open circuit in trimpots of recent make.

My thoughts were: If the trimpot between base and emitter accidentally were set to zero ohms when you're turning the amp on, the output devices were fully biased and perhaps destroyed.

Best regards!
 
Status
Not open for further replies.
Top Bottom