OK, so I'm hopefully going to be heading off to University to study Electronic Engineering and want to bring a bit of HiFi with me, but don't think I can bring a bi-amped pair of Monitor Audio RX6 speakers with their 19" control amp, and power amps with me along with me, I doubt they would fit in a medium sized cardboard box... 
I've got a very good ESI 24bit/96KHz USB audio interface that will work well with a miniature silent PC, as well as a pair of Gale Gold Monitors that I've seen hit surprisingly loud levels with only an SE EL84 tube amp at 4 watts. With this in mind (as well as the fact that I'll be living in a small room in a hall where loud music is considered undesirable) 3 watts of RMS power should be enough for what I need.
I've got a decent 16V single winding transformer lying about that I pulled out of a cheap mini system a few years back, which I'd like to use for the power supply as it'll be getting thrown out if I don't use it.
I would have liked to use MOSFET's for this, but I need to get as much voltage swing as possible on the output as I'm only using a 16.6V single supply, so a couple of compound pairs seem like the best bet. I've also added a voltage divider for the headphone output, the values are quite low, but I wanted good damping on the phones as I do most of my listening on the 325is anyway. For this reason, I have made the quiescent current a slightly high 100mA, so I can use my cans in what is basically class A mode.
I'm going to have 4 inputs (FM radio, audio interface etc.) mainly for the reason that I can do it with a 3 way 4 pole rotary switch I have lying around. All the devices used are ones I already have to bring costs down and use up parts, this is basically the amplifier equivalent to the fry-up people have before they go off on holiday. I'm pretty sure I can fit this thing in a pretty small enclosure.
Anyway I'm not all too experienced in discrete amplifier design, I calculated my values to be sensible, but if I've left anything out then I would be very grateful for some advice...
Schematics attached.
I've got a very good ESI 24bit/96KHz USB audio interface that will work well with a miniature silent PC, as well as a pair of Gale Gold Monitors that I've seen hit surprisingly loud levels with only an SE EL84 tube amp at 4 watts. With this in mind (as well as the fact that I'll be living in a small room in a hall where loud music is considered undesirable) 3 watts of RMS power should be enough for what I need.
I've got a decent 16V single winding transformer lying about that I pulled out of a cheap mini system a few years back, which I'd like to use for the power supply as it'll be getting thrown out if I don't use it.
I would have liked to use MOSFET's for this, but I need to get as much voltage swing as possible on the output as I'm only using a 16.6V single supply, so a couple of compound pairs seem like the best bet. I've also added a voltage divider for the headphone output, the values are quite low, but I wanted good damping on the phones as I do most of my listening on the 325is anyway. For this reason, I have made the quiescent current a slightly high 100mA, so I can use my cans in what is basically class A mode.
I'm going to have 4 inputs (FM radio, audio interface etc.) mainly for the reason that I can do it with a 3 way 4 pole rotary switch I have lying around. All the devices used are ones I already have to bring costs down and use up parts, this is basically the amplifier equivalent to the fry-up people have before they go off on holiday. I'm pretty sure I can fit this thing in a pretty small enclosure.
Anyway I'm not all too experienced in discrete amplifier design, I calculated my values to be sensible, but if I've left anything out then I would be very grateful for some advice...
Schematics attached.
Attachments
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Joined 2009
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rule 1: students aren't supposed to be worried about what is undesirable
rule 2: students never have enough RMS power
live on the wild side.
Yes, buy a rack mount semi-pro power amp. 250 to 700 watts per channel should be adequate. Then some 15" two-way (semi)pro speakers with a sensitivity approaching 100 dB. Then you will win the stereo wars, and probably get invited to a lot of parties.
On the other hand, if you really don't want much power, try a T-amp or YDA148 amp. $20 will get you one of each (including shipping from China), if you're undecided. Add an input selector switch and a 12V to 14V power supply, and you're done. The YDA148 chip includes (optional) active anti-clipping features, but requires heatsinking for 4 ohm loads. I'd still recommend a sensitive pair of speakers.
On the other hand, if you really don't want much power, try a T-amp or YDA148 amp. $20 will get you one of each (including shipping from China), if you're undecided. Add an input selector switch and a 12V to 14V power supply, and you're done. The YDA148 chip includes (optional) active anti-clipping features, but requires heatsinking for 4 ohm loads. I'd still recommend a sensitive pair of speakers.
under this approach you may as well go with the ''Pro " idea like having pro amp of 700 W and 15" 2way speakers together with a couple of stands , a couple of cables , a traktor or hercules controller and one laptop .... Then you may as well start your own PA business even before going to the university ,,,Trust me this will teach you a holly lot more in business than a universit
kind regards
sakis
I started my own business way before university ... The first small club i constructed for a costumer which included small PA system Dimmers lighting and so on was done when i was 16....at the age of 18 i was already working in the biggest club of Athens making 3 times the money of an average salary....
kind regards
sakis
I started my own business way before university ... The first small club i constructed for a costumer which included small PA system Dimmers lighting and so on was done when i was 16....at the age of 18 i was already working in the biggest club of Athens making 3 times the money of an average salary....
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I think it'd be worth you buying a more usable transformer, so that you can get a symmetric supply and lose all the coupling capacitor hassle. A 2x15V 100VA transformer only costs ~£20. Your cheap mini system transformer is only likely to be 30-50VA at most.
Consider the more usual LTP topology for the input and you could probably do without the regulation, which would get you a bit more swing.
Consider the more usual LTP topology for the input and you could probably do without the regulation, which would get you a bit more swing.
Improvements!
Thanks for the suggestions everyone. Somehow I don't think I'm going to be able to fit a pair of two way 15" 500W speakers on a medium sized desk top, let alone their amplifier, and at that sort of sound level I don't think anyone could hang on to their hearing for more than a few minutes at that level!
100dBW running at 200W RMS would work out to be a jaw dropping 123dB, louder than a jet aircraft taking off, and I don't want that in a small room , and I'm pretty sure anyone in adjacent rooms won't appreciate it all that much either... I can get enough RMS watts - but I can never seem to get enough dBW. After all the building will have it's own central heating .
A split supply LTP topology would be better, but I don't have any more money for components and transformers, so have to use the ones I already have and if I don't use them then they will probably end up getting thrown out by my Mother...
I've made a few improvements based on what was said, firstly I've taken away the regulation to get some better peak-to-peak on the output. In order to get the adequate supply rejection to do this, I've put a CCS in the VAS to increase open loop gain (also increasing linearity).
I've also added a shunt regulator into the front end to get better supply rejection as it has a low (but linear) open loop gain and would suffer from supply ripple. It also allows me to bias the input with a constant voltage. I've added a pot so I can adjust to get the best output symmetry when I test the amp to get symmetrical clipping.
I've also changed a few of the transistors to BC337/327 because of the need for extra driving capability of the output devices.
With the improvements I now have a minimum RMS output of 5.5 watts per channel! (Assuming a +20V rail with worst case conditions into a 6 ohm load), that means 98.4dB of RMS sound output with the speakers I have!
Schematics attached.
Thanks for the suggestions everyone. Somehow I don't think I'm going to be able to fit a pair of two way 15" 500W speakers on a medium sized desk top, let alone their amplifier
, and at that sort of sound level I don't think anyone could hang on to their hearing for more than a few minutes at that level!100dBW running at 200W RMS would work out to be a jaw dropping 123dB
, louder than a jet aircraft taking off, and I don't want that in a small room , and I'm pretty sure anyone in adjacent rooms won't appreciate it all that much either... I can get enough RMS watts - but I can never seem to get enough dBW. After all the building will have it's own central heating .A split supply LTP topology would be better, but I don't have any more money for components and transformers, so have to use the ones I already have and if I don't use them then they will probably end up getting thrown out by my Mother...
I've made a few improvements based on what was said, firstly I've taken away the regulation to get some better peak-to-peak on the output. In order to get the adequate supply rejection to do this, I've put a CCS in the VAS to increase open loop gain (also increasing linearity
). I've also added a shunt regulator into the front end to get better supply rejection as it has a low (but linear) open loop gain and would suffer from supply ripple. It also allows me to bias the input with a constant voltage. I've added a pot so I can adjust to get the best output symmetry when I test the amp to get symmetrical clipping.
I've also changed a few of the transistors to BC337/327 because of the need for extra driving capability of the output devices.
With the improvements I now have a minimum RMS output of 5.5 watts per channel! (Assuming a +20V rail with worst case conditions into a 6 ohm load), that means 98.4dB of RMS sound output with the speakers I have!
Schematics attached.
Attachments
As an engineering exercise using only parts you have to hand, you've done quite well here. Build it and see how it sounds, especially if it'll cost you nothing.
I think the only thing I would suggest now is leave room on your PCB for some TO247 sized output transistors. You might find the TO-220's are a bit small. Also should you decide you really need more supply voltage, you only have to change the transformer and output devices then. The pinout is the same so you can still use your TO-220 devices, just bend the leads a bit.
I think the only thing I would suggest now is leave room on your PCB for some TO247 sized output transistors. You might find the TO-220's are a bit small. Also should you decide you really need more supply voltage, you only have to change the transformer and output devices then. The pinout is the same so you can still use your TO-220 devices, just bend the leads a bit.
If you're going to study EE, you'll collect spares so buying a transformer is sensible. A high powered headphone amp would do fine, the Panda kit with better driver and output transistors would give you a very detailed high bandwidth amp with potential for modding or even us as a headphone amp later.
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Joined 2009
Paid Member
You'll get to play it loud at the weekend. When I was a student in a Hall of Residence, we'd all wheel our hi-fi speakers out into the corridor, order pizza and hold an indoor street party with everyone tuned in to the same FM station to listen to the top 40.
And then there was the guy who had BIG tower speakers that could play some real bass. It sounded like somebody doing masonry work a couple of floors below me. Wharfdale's they were, driven by Sansui. The kit took up a fair bit of space in his small room, but it was the envy of the building. Except the guy who had most of the parts of his Alfasud in his room until they kicked him out, but that's another story.
Cheapest option for you, go buy some speakers and an amp etc. from ebay, there's a ton of the stuff out there and you won't be violating any potential rules about home made electronics that aren't certified for electrical and fire safety.
And then there was the guy who had BIG tower speakers that could play some real bass. It sounded like somebody doing masonry work a couple of floors below me. Wharfdale's they were, driven by Sansui. The kit took up a fair bit of space in his small room, but it was the envy of the building. Except the guy who had most of the parts of his Alfasud in his room until they kicked him out, but that's another story.
Cheapest option for you, go buy some speakers and an amp etc. from ebay, there's a ton of the stuff out there and you won't be violating any potential rules about home made electronics that aren't certified for electrical and fire safety.
Student are now Time and Money poor (very poor wages, and very high rents)
Student life changed radically between in the UK between 1991 - 1999.
We all should give monty78pig credit for such realistic requirements, and he is probably more aware what University is like in the UK, than any members of this forum who are not a current student in the UK, and probably knows more about his budget than we do.
If we ignore monty78pig's requirements and remember our own time, I wish I had built a box with one or two Car battery's a hi efficiency amp (with a super flexible set of audio inputs, and a premium volume control such as an ALPS blue velvet) in a box with wheels and two detachable rain proof speakers with, the box would be suitable for locking to a tree. This would have been so cool at University as the best parties where often outside and without electricity, and I was not always in the mood to pack up when it rains. but I will resist hijacking monty78pig's thread unless he thinks building what I suggest is what he wants.
I think we should all congratulate monty78pig for designing an amplifier from discrete components. What was the inspiration and reasons for such a design? I am not a electrical designer, but an engineer and like to hear as many requirements as early and often as possible, and only know basics so cant comment on your circuit design skills, but theirs lots more to constructing an amplifier.
I think you should concentrate on the box the amplifier goes in, you will need portability and although my "Time Machine" amplifier was a system of much interest, but the wires and "the Blue Light" and the "magic smoke" coming out where much more popular with my friends than myself, when I demoed the amp spread across my bed, so I built a wooden tray with wires attaching all the boards with easy access, (Knowing more now, I would rip a broken amp apart for the metal box and mount points for controls.)
As for the design, I would suggest you also build a balanced input to your amplifier, as it will improve the sound from otherwise noisy music sources (eg some laptops on mains power).
Boxes are often the most expensive part of an amplifier. Followed by the transformer, heat-sink and the connectors. I think its time for you to focus on the box. Then the heat-sink and power supply, then get back to your circuit.
For an amplifier box (for a home system), I would suggest you buy broken second hand HiFi amplifiers, which you can look up the schematics and repair it, classic Hi end HiFi is usually better profits if you resell your repairs. You might find after repairing at no/low profit classic amps you get a queue of students willing to pay you a small profit.
When you can't fix the amplifier, that is the box you should use for your own design, it seems from reading your post, you want to build an amp, to gain skills and be super HiFi, would a chip amp with a good power supply do? I expect you will mostly be doing DIGITAL electronics, at Uni (Or later with a job) these days.
So size and portability are big priorities.
And not much power is needed, this is surprisingly low requirements, and potentially easy with a Class A transistor amp. With such low power you might want soft limiting to protect the tweeter?
I would suggest your first project should be to build a class A headphone amp if you could draw enough current, (with at least a 50% safety margin on the transformer if you don't want the transformer to get hot and start to hum), You might be able to talk your parents info buying you a nice big transformer, (or better a lab power supply), as they might see it as educational. Also having a class A amplifier gets significantly cheaper to build as you reduce the power requirements.
Is using the transformer a requirement? You seem to have designed a small class AB amp, (reminds me of Leak Delta) so maybe the transformer has not got enough current to drive stereo class A? Do you have its ratings, or a picture?
I think this is cool and practical but since most of the reason most old HiFi amps sound so bad is capacitors being long after their sell by date, a few hours, to order, and a few more to replace the old ones, and some scientific based work can leave you with a much improved Carboot sale amplifier, older models are often easier to repair as they are often simpler.
I also suggest that building or repairing HiFi is much easier, if you have two HiFi systems. if you don't want to have 2 HiFi amplifiers you will want to make at least one spare board for each board type in the box, so your not without music when building or modifying your HiFi.
Good luck, but for practical reasons, I would suggest you get hold of an old classic amp in broken condition, (heavier per watt the better), and models older than 1980 tend to have better boxes, (or if price is a priority, try the council tip you might find some things to buy or be given for much less), replace the transistors and capacitors. I normally only make things these days that I cant buy at a reasonable price, (usually software) and still I have more space than most students do to build things. I'm building subwoofers for my Electrostatics at the moment, and its a big task.
I think a multimeter, an osciliscope, a thermostatic solder station, easy to use solder, screw drivers (and other assemble / disassemble tools) will take up a lot of your HiFi space, and that is a minimum of tools. (and yes you do need an osciliscope if you want to build an amplifier and not a radio transmitter)
Student life changed radically between in the UK between 1991 - 1999.
We all should give monty78pig credit for such realistic requirements, and he is probably more aware what University is like in the UK, than any members of this forum who are not a current student in the UK, and probably knows more about his budget than we do.
If we ignore monty78pig's requirements and remember our own time, I wish I had built a box with one or two Car battery's a hi efficiency amp (with a super flexible set of audio inputs, and a premium volume control such as an ALPS blue velvet) in a box with wheels and two detachable rain proof speakers with, the box would be suitable for locking to a tree. This would have been so cool at University as the best parties where often outside and without electricity, and I was not always in the mood to pack up when it rains. but I will resist hijacking monty78pig's thread unless he thinks building what I suggest is what he wants.
I think we should all congratulate monty78pig for designing an amplifier from discrete components. What was the inspiration and reasons for such a design? I am not a electrical designer, but an engineer and like to hear as many requirements as early and often as possible, and only know basics so cant comment on your circuit design skills, but theirs lots more to constructing an amplifier.
I think you should concentrate on the box the amplifier goes in, you will need portability and although my "Time Machine" amplifier was a system of much interest, but the wires and "the Blue Light" and the "magic smoke" coming out where much more popular with my friends than myself, when I demoed the amp spread across my bed, so I built a wooden tray with wires attaching all the boards with easy access, (Knowing more now, I would rip a broken amp apart for the metal box and mount points for controls.)
As for the design, I would suggest you also build a balanced input to your amplifier, as it will improve the sound from otherwise noisy music sources (eg some laptops on mains power).
Boxes are often the most expensive part of an amplifier. Followed by the transformer, heat-sink and the connectors. I think its time for you to focus on the box. Then the heat-sink and power supply, then get back to your circuit.
For an amplifier box (for a home system), I would suggest you buy broken second hand HiFi amplifiers, which you can look up the schematics and repair it, classic Hi end HiFi is usually better profits if you resell your repairs. You might find after repairing at no/low profit classic amps you get a queue of students willing to pay you a small profit.
When you can't fix the amplifier, that is the box you should use for your own design, it seems from reading your post, you want to build an amp, to gain skills and be super HiFi, would a chip amp with a good power supply do? I expect you will mostly be doing DIGITAL electronics, at Uni (Or later with a job) these days.
and want to bring a bit of HiFi with me, but don't think I can bring a bi-amped pair of Monitor Audio RX6 speakers with their 19" control amp, and power amps with me along with me, I doubt they would fit in a medium sized cardboard box...
So size and portability are big priorities.
And not much power is needed, this is surprisingly low requirements, and potentially easy with a Class A transistor amp. With such low power you might want soft limiting to protect the tweeter?
I would suggest your first project should be to build a class A headphone amp if you could draw enough current, (with at least a 50% safety margin on the transformer if you don't want the transformer to get hot and start to hum), You might be able to talk your parents info buying you a nice big transformer, (or better a lab power supply), as they might see it as educational. Also having a class A amplifier gets significantly cheaper to build as you reduce the power requirements.
Is using the transformer a requirement? You seem to have designed a small class AB amp, (reminds me of Leak Delta) so maybe the transformer has not got enough current to drive stereo class A? Do you have its ratings, or a picture?
I think this is cool and practical but since most of the reason most old HiFi amps sound so bad is capacitors being long after their sell by date, a few hours, to order, and a few more to replace the old ones, and some scientific based work can leave you with a much improved Carboot sale amplifier, older models are often easier to repair as they are often simpler.
I also suggest that building or repairing HiFi is much easier, if you have two HiFi systems. if you don't want to have 2 HiFi amplifiers you will want to make at least one spare board for each board type in the box, so your not without music when building or modifying your HiFi.
Good luck, but for practical reasons, I would suggest you get hold of an old classic amp in broken condition, (heavier per watt the better), and models older than 1980 tend to have better boxes, (or if price is a priority, try the council tip you might find some things to buy or be given for much less), replace the transistors and capacitors. I normally only make things these days that I cant buy at a reasonable price, (usually software) and still I have more space than most students do to build things. I'm building subwoofers for my Electrostatics at the moment, and its a big task.
I think a multimeter, an osciliscope, a thermostatic solder station, easy to use solder, screw drivers (and other assemble / disassemble tools) will take up a lot of your HiFi space, and that is a minimum of tools. (and yes you do need an osciliscope if you want to build an amplifier and not a radio transmitter)
Design specification and brief!
First off I'm not going to spend a single penny buying parts for this amplifier, all of the parts featured in the design are those that I already have, and the design is optimised to use up as much space-hogging stuff that I have lying around as possible!
So, here's my revised brief in order of priority:
I have bought repaired and sold hifi on eBay to get by
for the past few years over the summer to get by, haven't done so this time because of devotion to exams, I mainly serviced and re-sold Akai reel to reels, I know the 4000DS and a few others like the back of my hand, replacing caps and belts never paid so well.
Regarding construction of my amp, all regulations will be observed and I will build it to a high, aesthetic, standard. As far as tolerance to getting stolen/dropped/flooded with alcoholic beverage/flooded with vomit, I'm not really into drinking, alcohol is heavily taxed where as Salvia, which is legal over here, isn't, with the added benefit of no hangover/vomit
. Thanks for the advice though, I'll have to build an security alarm too!
The amp will have to have unbalanced inputs, it will be used with a Technics ST-GT650 tuner as DAB (the equivalent of HD radio for those across the Atlantic) has disgustingly low bitrates (try listening to 112kbps MP2), high quality USB audio interface (I'm using an ESR so no ground loops), a small single cassette deck (laugh if you will but I have lots of classical commercial cassettes that are of acceptably quality).
Also, I have decided to reduce R15 to 220R, and R20 to 1k8, although a very minor reduction, it increases open loop gain slightly which results in better supply rejection and lower distortion.
I intend this amp to be a bit of fun to build as well as a useful way to use up parts that would otherwise be thrown out, my room is a real mess and as soon as I'm gone, my Mum will be in there with a bin bag...
TLDR;
First off I'm not going to spend a single penny buying parts for this amplifier, all of the parts featured in the design are those that I already have, and the design is optimised to use up as much space-hogging stuff that I have lying around as possible!
So, here's my revised brief in order of priority:
- The amplifier must use parts I already have, lots of em , and complexity is preferred as long as it is worth it in performance terms.
- The amplifier must use my 16.5V transformer (it looks and feels at least 30VA, picture attached with CD for comparison, measures 50x60x55 excluding pins).
- The amplifier must fit into a 300x200x100 aluminium enclosure I have also have lying around (it was for a tube project that never was, a couple of years back, along with 5 Panasonic FC 4700uF 25V caps I got from RS a while back but never used).
- The amplifier must have a RMS power of least 4 watts and have good performance within it's limits, it will be driving 91Db/W speakers at considerate levels, it is not intended to be a party device, but to reproduce music accurately at moderate levels , besides I've heard my Gale's go painfully loud with just 2 watts RMS.
- Life is tough for students in the UK at the moment and the amplifier must be relatively power efficient, squeezing every last watt out of that transformer, I'll more than likely be paying for every KW/hr of energy I use through the nose , the less I use the better as every little helps. This rules out Class A (I'll probably already have a heater ).
- To impress people on my course with my design and build (especially build) skills. Judging by what I've seen most of them are still learning logic gates and MOSFETs (which is what A level teaches now instead of any other transistor) ...
- 16.5V transformer.
- 5x 4700uF FC 35V caps, the only ones I have.
- MJE15030/MJE15031, BC560/BC550, BC327/BC337, BC548, LM350K, MC7812.
- All E12 values of caps from 10p to 100uF.
- All E24 values of resistors from 1 ohm to 10M ohm.
- All E6 caps from 100uF to 1000uF, FC series.
- Binding posts, rca panel mount connectors, mains filter IEC power socket, various spacers and appropriate fixings.
- ALPS 10K and 22K log pot.
- 4way3pole BBM switch.
- 5mm LED's, red, green and yellow, with panel mount holders.
- Lots of wire.
- General diy electroics tools, mini lcd oscilloscope, benchtop PSU (20V 2A), several multimeters, function generator (not for THD tests, of course ), etc.
- An old 1C/W heatsink.
I have bought repaired and sold hifi on eBay to get by
for the past few years over the summer to get by, haven't done so this time because of devotion to exams, I mainly serviced and re-sold Akai reel to reels, I know the 4000DS and a few others like the back of my hand, replacing caps and belts never paid so well
.Regarding construction of my amp, all regulations will be observed and I will build it to a high, aesthetic, standard. As far as tolerance to getting stolen/dropped/flooded with alcoholic beverage/flooded with vomit, I'm not really into drinking, alcohol is heavily taxed where as Salvia, which is legal over here, isn't, with the added benefit of no hangover/vomit
. Thanks for the advice though, I'll have to build an security alarm too!The amp will have to have unbalanced inputs, it will be used with a Technics ST-GT650 tuner as DAB (the equivalent of HD radio for those across the Atlantic) has disgustingly low bitrates (try listening to 112kbps MP2), high quality USB audio interface (I'm using an ESR so no ground loops), a small single cassette deck (laugh if you will but I have lots of classical commercial cassettes that are of acceptably quality).
Also, I have decided to reduce R15 to 220R, and R20 to 1k8, although a very minor reduction, it increases open loop gain slightly which results in better supply rejection and lower distortion.
I intend this amp to be a bit of fun to build as well as a useful way to use up parts that would otherwise be thrown out, my room is a real mess and as soon as I'm gone, my Mum will be in there with a bin bag
...TLDR;
- I have all the parts/tools/test equipment/experience I need and live and breathe electronics, this is the cheapest way.
- I already have a nice system at home
- With my speakers, 5.5 watts is loud enough, quality matters more than raw power to me, I have a broad range of musical taste and prefer listening conditions other than very loud (I use headphones most of the time anyway), most club music that will end up getting played loud is hyper compressed (8dBFs is common), so no problem there!
- I need to use up components, this is the best way!
- I've already built a very nice Class A headphone amp! Also see attached.
Attachments
What? No chip amp??
So the heatsink may be your missing part?
Regarding the booze, I thought you were going to be studying in London where home brew used to reign supreme.
I only build speakers but all I remember of university life is late nite trade school classes followed by heavy drinking sessions at the local
So the heatsink may be your missing part?
Regarding the booze, I thought you were going to be studying in London where home brew used to reign supreme.
I only build speakers but all I remember of university life is late nite trade school classes followed by heavy drinking sessions at the local
The easiest and quickest way would be a good car radio with AUX input. You'll need to build only an enclosure with power supply and input selector. The radio could be swapped between this and your car (after all you're supposed to be a poor student) and no worry if it get's stolen: there are so many cars around ;-)
Hi Monty,
I've been following this thread, and enjoying the commentary and your well reasoned responses to all of the "suggestions." I like the headphone amplifier design, very elegant..
The power transformer looks reasonably sized for the task at hand and I would guess it is significantly more than 30VA I'd guess something over 60VA..
Good luck in school!
I've been following this thread, and enjoying the commentary and your well reasoned responses to all of the "suggestions." I like the headphone amplifier design, very elegant..
The power transformer looks reasonably sized for the task at hand and I would guess it is significantly more than 30VA I'd guess something over 60VA..
Good luck in school!
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