Hi,
the 2n3055 come in different versions which have different characteristics.
Similarly, different suppliers (smaller companies & fakes) may not reach the published specs from the big reputable manufacturers.
The 3055 was a slow, low gain, low voltage output device. Take care to replicate these characteristics.
The gain is possibly the least sensitive of these. You may improve performance, very slightly, by selecting a higher gain device that maintains a more linear gain characteristic over a wider range of operating currents.
A higher voltage device could be substituted but high voltage is usually designed in at the expense of some other characteristic, be careful.
the 2n3055 come in different versions which have different characteristics.
Similarly, different suppliers (smaller companies & fakes) may not reach the published specs from the big reputable manufacturers.
The 3055 was a slow, low gain, low voltage output device. Take care to replicate these characteristics.
The gain is possibly the least sensitive of these. You may improve performance, very slightly, by selecting a higher gain device that maintains a more linear gain characteristic over a wider range of operating currents.
A higher voltage device could be substituted but high voltage is usually designed in at the expense of some other characteristic, be careful.
I have spent at least 30 mins on two occasions looking on the site for any thing that refers to this amp but I have found no info! So any help will be appreciated.
Mainly with regards to decent output and driver transistors as the amp is a reasonable simple affair.
I would like to know what are consisdered the best devices in the sub 50 watt 8ohm class of amp.
regards Trev
Mainly with regards to decent output and driver transistors as the amp is a reasonable simple affair.
I would like to know what are consisdered the best devices in the sub 50 watt 8ohm class of amp.
regards Trev
The whole idea is to extend the amplifier bandwidth and linearity etc
I have full facilities ie oscillators ,scopes distortion analysers etc.
I have asked this question as I am not up to speed on the latest devices available ! I want to find what are the flavour of the month at this moment?
My idea is to modify the dead channel and then compare it with the existing channel.
So please give me your suggestions
Circuit topology seams to be an npn diff pair fed via a two transistor current source
the output is then fed into a PNP driver that has a two transistor constant current load
Output stage isa pair of fully complimentary emitter followers.
protection is the normal type of complimetary transistors that monitor the emitter current of the output devices and then divert the drive current if required
Regards Trev
I have full facilities ie oscillators ,scopes distortion analysers etc.
I have asked this question as I am not up to speed on the latest devices available ! I want to find what are the flavour of the month at this moment?
My idea is to modify the dead channel and then compare it with the existing channel.
So please give me your suggestions
Circuit topology seams to be an npn diff pair fed via a two transistor current source
the output is then fed into a PNP driver that has a two transistor constant current load
Output stage isa pair of fully complimentary emitter followers.
protection is the normal type of complimetary transistors that monitor the emitter current of the output devices and then divert the drive current if required
Regards Trev
Oh, then perhaps you can look at the outputs used on the SymAsym - several have tried this amp designed by MikeB, and like it:
http://www.lf-pro.net/mbittner/Sym5_Webpage/symasym5_3.html
Several DIYrs have also tried other output transistors on the same amp, but you'll have to hunt it down in a rather long thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=60918&perpage=10&highlight=&pagenumber=1
http://www.lf-pro.net/mbittner/Sym5_Webpage/symasym5_3.html
Several DIYrs have also tried other output transistors on the same amp, but you'll have to hunt it down in a rather long thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=60918&perpage=10&highlight=&pagenumber=1
Hi,
do not buy 2sc3281/2sa1302. there are fakes in the market to replace these long obsolete devices.
Similarly take care to buy genuine 2sa1943/2sc5200 which are Toshiba's replacement.
Onsemi do an equivalent MJ(L)1302/3281 and also a high voltage version with more low current gain MJ(L)4302/4281.
Sanken do a range of high speed, high gain output devices that have an excellent reputation, but in some markets they are less than competitively priced. 2sa1215, 1216, 1294, 1295, 1303.
If you want a halfway house then the very robust 15003/4 and 21193/4 in To3 case will drive almost any load from +-35V when paired up. There are also a wide selection of 10MHz devices
When selecting devices, look at fT, gain @ 100mA and @ 5A, I @ rail to rail voltage, I @ rail to ground voltage, Mounting type (To3,Mt200,To264,To247=Mt100,To220, in decreasing dissipation ability).
Download Data Sheets before making final decision.
You should look at your existing PCB to ensure there are locations (used or empty) to adjust HF compensation when you propose a major change in device characteristics.
You can add a full Thiel Network to the output terminals rather than on the PCB (some designers say this is the better location anyway) if there is insufficient space.
You need a schematic, buy, borrow or reverse engineer.
Many amplifiers respond more to improved power supply. This is partly due to skimping on the PSU because this is the second most expensive item after the chassis (or do we include distribution costs? then it's third dearest). transformer, capacitors, RC snubbers, interference suppression, spike attenuation, all come into PSU mods.
Input filtering can have a profound effect on the final sound.
Remove all high K ceramics that have variable voltage across them.
do not buy 2sc3281/2sa1302. there are fakes in the market to replace these long obsolete devices.
Similarly take care to buy genuine 2sa1943/2sc5200 which are Toshiba's replacement.
Onsemi do an equivalent MJ(L)1302/3281 and also a high voltage version with more low current gain MJ(L)4302/4281.
Sanken do a range of high speed, high gain output devices that have an excellent reputation, but in some markets they are less than competitively priced. 2sa1215, 1216, 1294, 1295, 1303.
If you want a halfway house then the very robust 15003/4 and 21193/4 in To3 case will drive almost any load from +-35V when paired up. There are also a wide selection of 10MHz devices
When selecting devices, look at fT, gain @ 100mA and @ 5A, I @ rail to rail voltage, I @ rail to ground voltage, Mounting type (To3,Mt200,To264,To247=Mt100,To220, in decreasing dissipation ability).
Download Data Sheets before making final decision.
You should look at your existing PCB to ensure there are locations (used or empty) to adjust HF compensation when you propose a major change in device characteristics.
You can add a full Thiel Network to the output terminals rather than on the PCB (some designers say this is the better location anyway) if there is insufficient space.
You need a schematic, buy, borrow or reverse engineer.
Many amplifiers respond more to improved power supply. This is partly due to skimping on the PSU because this is the second most expensive item after the chassis (or do we include distribution costs? then it's third dearest). transformer, capacitors, RC snubbers, interference suppression, spike attenuation, all come into PSU mods.
Input filtering can have a profound effect on the final sound.
Remove all high K ceramics that have variable voltage across them.
Hi,
both are referred to as To3p.
To247 is about 16mm by 20mm.
To264 is about 20mm by 26mm.
Both have a single hole mounting.
Some have an isolated screw hole that needs only a plain isolator between the metal tab and heatsink for electric insulation. Some have the metal tab very close to the screw fixing and need an isolating bush for true electrical insulation.
The screw hole diameter seems to vary between 3.1mm (3mm) and 3.6mm (3.5mm or No6). I suspect this is defined in a standard somewhere and may be why some manufacturers state different case codes for their product even though superficially they look similar.
I notice that the Scottish (Scotch) version is omitted from your observation. Is that because one can never have too much whisky?
both are referred to as To3p.
To247 is about 16mm by 20mm.
To264 is about 20mm by 26mm.
Both have a single hole mounting.
Some have an isolated screw hole that needs only a plain isolator between the metal tab and heatsink for electric insulation. Some have the metal tab very close to the screw fixing and need an isolating bush for true electrical insulation.
The screw hole diameter seems to vary between 3.1mm (3mm) and 3.6mm (3.5mm or No6). I suspect this is defined in a standard somewhere and may be why some manufacturers state different case codes for their product even though superficially they look similar.
is this a hint that I talk too much?
I notice that the Scottish (Scotch) version is omitted from your observation. Is that because one can never have too much whisky?
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