Alright, here goes!
A couple years back my dad, who is a bit of an audiophile, gave me some really great, brand spanking new Bose speakers as a birthday present, and gave me his old Sony TA-1055 amp to drive them; something of a rite of passage present your might call it (was for my 18th after all). The TA-1055 was a phenomenal piece of hardware, and drove my Bose desktops beautifully, but it's quite old and started showing its age, giving me quite a lot of problems, I was repairing it every second week. Finally, a couple months back, it broke once and for all, and to be honest, I don't feel like spending the cash or time on troubleshooting it at the moment, and would rather build myself a brand new amp.
So... I'm an audio amplifier noob, but not an electronics noob; I'm a third year electronic engineering student and I'm pretty damn good at what I study.. Dare I say I'm level with many people on this site with my electronics grounding? I doubt that, most of you are probably far wiser than me, which is why I come to you for help! But still, I'm just saying have some potential
My plan then, and some questions:
I want to build a desktop amp, preferably paint it matte black with a darkened perspex front, with my control interfaces and some digitally driven displays shining via LCD's through abovementioned darkened perspex (This eye-candy and control stuff I'll elaborate on some other time; I'm quite capable of doing this as I'm good and pretty experienced when it comes to basic digital stuff; but for the purpose of suggestions you may have, take into account I'll need a 5V rail and probably about 50W of power, for safeties sake, to run this part of my amp).
I want the amplifier to run somewhere between 50 - 75W RMS (I think thats good enough for desktop speakers?) and to have some sort of pre-amp equalizer controls. I would love it to be a transistor based amp, as I'm very interested in that area of study and I need the experience; as well as the fact that I live in South Africa, so acquiring more complex amplifier IC's might be difficult (although op-amps are readily available, I don't think they give good sound quality?)
I may like to partly control the amp via IR; the amp will be next to my PC, but sometimes I might like to control it from across the room. Mostly, I'd do this as its a challenge to do! I have some experience with IR, built an IR motor speed controller last year, so I'm not a complete noob, but I understand I might be biting off a little more than I can chew with this idea, crit me if you want, I can always add this bit later I surmise.
Finally; I want to build it myself, ground up, no kits! Circuit schematics are okay, but all the physical work I would like to do myself, make it a labour of love. I have a good grasp on making and using PCBs, I have ultiboard and multisim for circuit design and testing, and in then end... I want it to be mine. Or mostly mine at least...
The questions I have for you then:
Where to start? Any good circuit schematics, good internet resources to look at, nice starting amps? Power Supplies; do I have to fork out half the cost of the amp to buy a transformers? Or will a cheapish 18-0-18 transformer work? I know almost nothing about amplifer's power needs, this is my biggest area of difficulty. (I have a 300W PC PSU, could I use that? Or the old PS in the TA-1055, though I'd prefer to save the old amp; its pretty vintage). Finally, any suggestions? I promise to put up pretty pictures of the amp when I'm done, share my circuit diagrams with the world...
Thanks for anyone who read the above, its hella long and probably mostly boring, any tips and correspondance would be much appreciated!
A couple years back my dad, who is a bit of an audiophile, gave me some really great, brand spanking new Bose speakers as a birthday present, and gave me his old Sony TA-1055 amp to drive them; something of a rite of passage present your might call it (was for my 18th after all). The TA-1055 was a phenomenal piece of hardware, and drove my Bose desktops beautifully, but it's quite old and started showing its age, giving me quite a lot of problems, I was repairing it every second week. Finally, a couple months back, it broke once and for all, and to be honest, I don't feel like spending the cash or time on troubleshooting it at the moment, and would rather build myself a brand new amp.
So... I'm an audio amplifier noob, but not an electronics noob; I'm a third year electronic engineering student and I'm pretty damn good at what I study.. Dare I say I'm level with many people on this site with my electronics grounding? I doubt that, most of you are probably far wiser than me, which is why I come to you for help! But still, I'm just saying have some potential
My plan then, and some questions:
I want to build a desktop amp, preferably paint it matte black with a darkened perspex front, with my control interfaces and some digitally driven displays shining via LCD's through abovementioned darkened perspex (This eye-candy and control stuff I'll elaborate on some other time; I'm quite capable of doing this as I'm good and pretty experienced when it comes to basic digital stuff; but for the purpose of suggestions you may have, take into account I'll need a 5V rail and probably about 50W of power, for safeties sake, to run this part of my amp).
I want the amplifier to run somewhere between 50 - 75W RMS (I think thats good enough for desktop speakers?) and to have some sort of pre-amp equalizer controls. I would love it to be a transistor based amp, as I'm very interested in that area of study and I need the experience; as well as the fact that I live in South Africa, so acquiring more complex amplifier IC's might be difficult (although op-amps are readily available, I don't think they give good sound quality?)
I may like to partly control the amp via IR; the amp will be next to my PC, but sometimes I might like to control it from across the room. Mostly, I'd do this as its a challenge to do! I have some experience with IR, built an IR motor speed controller last year, so I'm not a complete noob, but I understand I might be biting off a little more than I can chew with this idea, crit me if you want, I can always add this bit later I surmise.
Finally; I want to build it myself, ground up, no kits! Circuit schematics are okay, but all the physical work I would like to do myself, make it a labour of love. I have a good grasp on making and using PCBs, I have ultiboard and multisim for circuit design and testing, and in then end... I want it to be mine. Or mostly mine at least...
The questions I have for you then:
Where to start? Any good circuit schematics, good internet resources to look at, nice starting amps? Power Supplies; do I have to fork out half the cost of the amp to buy a transformers? Or will a cheapish 18-0-18 transformer work? I know almost nothing about amplifer's power needs, this is my biggest area of difficulty. (I have a 300W PC PSU, could I use that? Or the old PS in the TA-1055, though I'd prefer to save the old amp; its pretty vintage). Finally, any suggestions? I promise to put up pretty pictures of the amp when I'm done, share my circuit diagrams with the world...
Thanks for anyone who read the above, its hella long and probably mostly boring, any tips and correspondance would be much appreciated!
First thing to do is break it down into sections:
* Input selector - if you want more than one input. Simplest thing is a rotary switch. If you're thinking future control by a microcontroller, then use relays. Telecommunications relays (for example Omron G5V-2) are ideal. Driving them is obvious
* Preamp - basically, your volume control. If you want to control volume via remote, then there's two solutions - either get a motorised potentiometer and control that, or use an IC such as the TI PGA2311. If sourcing exotic IC's is going to be a problem, you will have to go for the first route.
* Power amp - obviously the guts. There's quite a few neat schematics around here. I would recommend both MikeB's SymAsym and Destroyer X's DX amp, however these really want output devices that again, you might find hard to get reliably. In that case, I recommend Sixtek's ST151 amplifier which is fairly flexible in which parts you can use.
* Power supply - Bad news, +5V and PC power supplies no good here. Good news, building a basic unregulated linear supply to feed the power amp is very easy. Making a symmetric supply for opamps is also quite easy.
I hope this is enough to get you going with
* Input selector - if you want more than one input. Simplest thing is a rotary switch. If you're thinking future control by a microcontroller, then use relays. Telecommunications relays (for example Omron G5V-2) are ideal. Driving them is obvious
* Preamp - basically, your volume control. If you want to control volume via remote, then there's two solutions - either get a motorised potentiometer and control that, or use an IC such as the TI PGA2311. If sourcing exotic IC's is going to be a problem, you will have to go for the first route.
* Power amp - obviously the guts. There's quite a few neat schematics around here. I would recommend both MikeB's SymAsym and Destroyer X's DX amp, however these really want output devices that again, you might find hard to get reliably. In that case, I recommend Sixtek's ST151 amplifier which is fairly flexible in which parts you can use.
* Power supply - Bad news, +5V and PC power supplies no good here. Good news, building a basic unregulated linear supply to feed the power amp is very easy. Making a symmetric supply for opamps is also quite easy.
I hope this is enough to get you going with
Since as you seem unsure about the power supply side, I thought this article would be a big help to you:
http://sound.westhost.com/psu-wiring.htm
The 35-0-35 supply voltage shown in that circuit will power ST151 adequately for 50W into 8 ohms. I'd look for a 160VA transformer, larger is OK, but not larger than 300VA or you will have to deal with switching the inrush current. Toroidal transformers are generally best, but use what you can get.
If you have any preamp or op-amp based circuits, they will want a symmetric 15V supply (+15V and -15V with respect to ground). It will need to be regulated. You may be familiar with regulator IC's such as LM317 already - this and it's negative version LM337 will make an adequate circuit for supplying any op-amp based circuits such as preamps/tone controls you may want. You can use the 35V outputs from the power amp circuit- just make sure you heat sink the regulator IC's well as they will get rather hot.
http://sound.westhost.com/psu-wiring.htm
The 35-0-35 supply voltage shown in that circuit will power ST151 adequately for 50W into 8 ohms. I'd look for a 160VA transformer, larger is OK, but not larger than 300VA or you will have to deal with switching the inrush current. Toroidal transformers are generally best, but use what you can get.
If you have any preamp or op-amp based circuits, they will want a symmetric 15V supply (+15V and -15V with respect to ground). It will need to be regulated. You may be familiar with regulator IC's such as LM317 already - this and it's negative version LM337 will make an adequate circuit for supplying any op-amp based circuits such as preamps/tone controls you may want. You can use the 35V outputs from the power amp circuit- just make sure you heat sink the regulator IC's well as they will get rather hot.
Thanks a lot for the help jaycee, hugely appreciated! I have somewhere to start.
I've got a lot to mull over, just started reading through the power supply stuff. I'm relatively familiar with power supplies; I built two last year, I'm just completely befuddled when it comes to their functioning in a traditional audio amplifier. A case of too much theory and too little practice i think. So, i understand the basics of ps, just not what I should be looking at for this amp, so i'll get reading.
I did find a 2x0v-50v, 160VA transformer at a reasonable priced (+- R350/$50/30 punds), would that be a worthwhile purchase? Also, i've been toying with the idea of building my PS as an external unit, reducing noise and shielding costs, etc, then running a line from the external PS unit to the amp on my desk. Good idea, bad idea?
Amp wise, Sixtek's is a nice simple amp, and relatively cheap (I ran the components by a local electronics store, scraping in under R220; about 30 dollars/20 pounds, for one channel and not including the ps, or the heat sinks), and I think thats pretty good? But! I ran that DXamp's part list, which looked very interesting, by the same store, and they stock them all; if the output devices you spoke of were the 2SA1943 and the 2SC5200 transistors, i can get them quite easily, and the other transistors are all pretty standard. This amp is a little bit more expensive, but I'm willing to pay for it, if it is the better choice?
As for an input selector; the amp is aimed mainly at a stereo input from my PC/Ipod; just a left and right channel, and I dont really need anymore than that, so I think an input selector is needless, though it might be fun to put one in... I'll think about it.
Pre-amp wise, my friend pointed me in the direction of a really neat digital potentiometer today, I'm going to look into that further, sounds like it will make IR control a whole lot easier. The other goal of the preamp was to have a little control over the system's bass and treble; or is it better if i control that from the input device side, from a complexity point of view, especially as this is my first amp?
I've had a little experience with regulator IC's, but far from enough. I'll go do some research into them later tonight, pull up datasheets and the like, but I understand why they'll be needed.
Once again thanks for the help jaycee, huge kudos! Any more advice would be great!
I've got a lot to mull over, just started reading through the power supply stuff. I'm relatively familiar with power supplies; I built two last year, I'm just completely befuddled when it comes to their functioning in a traditional audio amplifier. A case of too much theory and too little practice i think. So, i understand the basics of ps, just not what I should be looking at for this amp, so i'll get reading.
I did find a 2x0v-50v, 160VA transformer at a reasonable priced (+- R350/$50/30 punds), would that be a worthwhile purchase? Also, i've been toying with the idea of building my PS as an external unit, reducing noise and shielding costs, etc, then running a line from the external PS unit to the amp on my desk. Good idea, bad idea?
Amp wise, Sixtek's is a nice simple amp, and relatively cheap (I ran the components by a local electronics store, scraping in under R220; about 30 dollars/20 pounds, for one channel and not including the ps, or the heat sinks), and I think thats pretty good? But! I ran that DXamp's part list, which looked very interesting, by the same store, and they stock them all; if the output devices you spoke of were the 2SA1943 and the 2SC5200 transistors, i can get them quite easily, and the other transistors are all pretty standard. This amp is a little bit more expensive, but I'm willing to pay for it, if it is the better choice?
As for an input selector; the amp is aimed mainly at a stereo input from my PC/Ipod; just a left and right channel, and I dont really need anymore than that, so I think an input selector is needless, though it might be fun to put one in... I'll think about it.
Pre-amp wise, my friend pointed me in the direction of a really neat digital potentiometer today, I'm going to look into that further, sounds like it will make IR control a whole lot easier. The other goal of the preamp was to have a little control over the system's bass and treble; or is it better if i control that from the input device side, from a complexity point of view, especially as this is my first amp?
I've had a little experience with regulator IC's, but far from enough. I'll go do some research into them later tonight, pull up datasheets and the like, but I understand why they'll be needed.
Once again thanks for the help jaycee, huge kudos! Any more advice would be great!
Hey there, I'm the SA, DX man... the plain DX can be build for just over R100 useing budget components... from local supliers like RS and Mantech... Get the 5200/1943 from communica as they stock ISC ones, the other local toshibas are fake...
Feel free to contact me for assistance if you wish to go down this route....
Feel free to contact me for assistance if you wish to go down this route....
One mistake I think you might have made with the power supply... AC voltage from transformer secondary != DC voltage once rectified and smoothed. A transformer with 50V secondary windings would give you nearly 70V DC supplies. The general rule of thumb is AC Voltage * 1.414 = DC voltage. For your amp, you'll want about 35V, so you will want a transformer with 25V secondaries.
Thanks for the help. Jaycee, i noticed the error of my ways almost as soon as I posted that, just never got around to editing it; i forgot that transformers are rated at RMS voltages. Nordic, I kind of jumped the gun on you there; I priced my parts through RS and Mantech last night; I cant get everything for quite R100 bucks, more like R150, but for an amp like this I think thats well worth it. I'll probably purchase from Mantech in the end, visited their Durban premises today and they were very helpful.
The transformer is still my biggest issue cost wise; Mantech quoted me R640 for a 25-0-25, 225VA transformer!! Thats a little too much for me, so I'll take to the yellow pages to see if I can find a cheaper one.
So I'm pretty much set on building the DXamp now, but I'm still needing a little help. I'm going to build one channel first, then purchase the rest and build the second amp, take things slowly. My questions then:
I understand the schematic for the DXAmp's PS that Carlos has on dxamp.com, except why the two induction coils are present, could someone enlighten me? Also, I'm presuming that one PS could power both my channel's amps, as well as my preamp (via regulation, thanks for those IC's jaycee)? I'd rather take any small quality hit that a single PS might cause if it kept a little cash in my pocket, I'm only a student after all.
The DXamp is pretty complicated; I'm relatively good with transistor based amplification, so I can keep up with most of the schematic, although I'm a little too lazy to do most of the calculations to further my understanding. Probably my main point of confusion would be the bias servo.. I understand the principles of biasing, but could someone just give me a more info on it... I'm feeling a little lost. Also, there doesn't seem to be a schematic, parts list or PCB for the bias servo.. Im a novice, i apologize in advance for my silly questions
Finally, cooling. Looking at some of the photos in the DXamp thread, a relatively standard heatsink seems to suffice for the output transistors, nothing crazy, but what will I need for the bias servo and my preamp's power regulators. Also, probably a question for later, but I will be making a nice enclosure for the amp; will I need a fan or two to cool it down?
Thanks for the help all you guys, hugely appreciated!
Nice to have some South African aid too; Nordic, I saw you were quite involved in the DXamp's design when I checked the thread, was great seeing a local presence on the forums, I thought I was all alone...
The transformer is still my biggest issue cost wise; Mantech quoted me R640 for a 25-0-25, 225VA transformer!! Thats a little too much for me, so I'll take to the yellow pages to see if I can find a cheaper one.
So I'm pretty much set on building the DXamp now, but I'm still needing a little help. I'm going to build one channel first, then purchase the rest and build the second amp, take things slowly. My questions then:
I understand the schematic for the DXAmp's PS that Carlos has on dxamp.com, except why the two induction coils are present, could someone enlighten me? Also, I'm presuming that one PS could power both my channel's amps, as well as my preamp (via regulation, thanks for those IC's jaycee)? I'd rather take any small quality hit that a single PS might cause if it kept a little cash in my pocket, I'm only a student after all.
The DXamp is pretty complicated; I'm relatively good with transistor based amplification, so I can keep up with most of the schematic, although I'm a little too lazy to do most of the calculations to further my understanding. Probably my main point of confusion would be the bias servo.. I understand the principles of biasing, but could someone just give me a more info on it... I'm feeling a little lost. Also, there doesn't seem to be a schematic, parts list or PCB for the bias servo.. Im a novice, i apologize in advance for my silly questions
Finally, cooling. Looking at some of the photos in the DXamp thread, a relatively standard heatsink seems to suffice for the output transistors, nothing crazy, but what will I need for the bias servo and my preamp's power regulators. Also, probably a question for later, but I will be making a nice enclosure for the amp; will I need a fan or two to cool it down?
Thanks for the help all you guys, hugely appreciated!
Nice to have some South African aid too; Nordic, I saw you were quite involved in the DXamp's design when I checked the thread, was great seeing a local presence on the forums, I thought I was all alone...
Jonathan Turck said:
The coils form what is called a CLC filter (capacitor, inductor, capacitor). It's basically just to "clean up" the supply. It's not 100% essential - the resistors and the inductors wound around them could just be replaced with links.
Jonathan Turck said:
Yes, one supply will work just fine for powering the power amps, and if you use a 25-0-25 transformer (giving 35V supply rails) you will be able to run an LM317/337 based circuit from there to provide 15V supplies for any op amps.
Jonathan Turck said:
The circuit design is based on a circuit known as the "Lin" design. You may want to look that up, or if you're at college/university, look in some books.
Jonathan Turck said:
Also, there doesn't seem to be a schematic, parts list or PCB for the bias servo.. Im a novice, i apologize in advance for my silly questions
The bias servo basically maintains a constant voltage between the bases of the driver transistors. This effectively sets the standing current through the output stage - you may have heard of "biasing an amp". It also performs thermal regulation - as transistors heat up, they will pass more current, which makes them hotter.. etc. The bias servo regulates the current flowing through the output stage, to prevent thermal runaway.
Jonathan Turck said:
The bias servo will mount on the heatsink in between the output transistors - it has to go here to pick up the thermal feedback from the outputs, so that it can maintain the bias voltage. If it isn't mounted there, the amp goes into "thermal runaway" which basically means the transistors get hotter and hotter and.. *BANG*.
If you build a preamp supply then the regulators will need heatsinks - these can be the kind you get for mounting to TO-220 packaged devices.
Jonathan Turck said:
I would say as long as you use a good size heatsink and have some ventilation holes in the top and bottom, then no, you won't need a fan.
That transformer should be adequate....
The amp on DXAMP.com is the HRII, the original DX amp is hosted by Greg Erskine.. just check Carlos' signature for the URL... it is a simpler/cheaper build...
The PSU is realy good... I don't think you even need that thick wire there...
I would make two PSU's though, to at least seperate the channels through the banks of capacitors... and feed that from that transformer in parallel...
The amp is a 3 stage design, meaning you do not need a preamp.... (it just adds more stages of distortion), If gain is a problem it can be corrected with two resistors... (considering the mp3 player source, you may want to do that.)
The HRII is superior to the DX in every way... (i.m.o)
Beware mantech 2sc5200 is fake
This is what is inside
Try to get the ISC ones, or fairchild... local stock of those seem fine copies.
The amp on DXAMP.com is the HRII, the original DX amp is hosted by Greg Erskine.. just check Carlos' signature for the URL... it is a simpler/cheaper build...
The PSU is realy good... I don't think you even need that thick wire there...
I would make two PSU's though, to at least seperate the channels through the banks of capacitors... and feed that from that transformer in parallel...
The amp is a 3 stage design, meaning you do not need a preamp.... (it just adds more stages of distortion), If gain is a problem it can be corrected with two resistors... (considering the mp3 player source, you may want to do that.)
The HRII is superior to the DX in every way... (i.m.o)
Beware mantech 2sc5200 is fake
This is what is inside
Try to get the ISC ones, or fairchild... local stock of those seem fine copies.
Hi Johnathan
For information on biasing and SS amps in general I would recommend Doug Self's book:
http://www.dself.dsl.pipex.com/ampins/books/book.htm
It should appeal to you an Engineer (it's technical).
----------------------
I built the standard DX amp, it's wonderful!! Gonna build the HR when it's warm enough to get back into my garage.
Cheers
Andrew
For information on biasing and SS amps in general I would recommend Doug Self's book:
http://www.dself.dsl.pipex.com/ampins/books/book.htm
It should appeal to you an Engineer (it's technical).
----------------------
I built the standard DX amp, it's wonderful!! Gonna build the HR when it's warm enough to get back into my garage.
Cheers
Andrew
Wow, a lot of really useful info their guys, thanks for all the feedback! I've run across a little snag, with funding actually, forgot about valentines day and the obligatory dinner, flowers and gifts that come with it, not a cheap affair to say the least. So I'm a little strapped for cash, going to have to wait til I get paid before I purchase the transformer. I've got enough for the rest of the parts, at least for one channel, so I'm going to go grab the components early next week... My Faculty will let me raid their stores for the smaller resistors and caps, and I'm gonna see If I can get those big wattage resistors and the PS caps from them too, as well as some of the smaller transistors; as it is I have quite a few lying around at home, mostly BC547s and their derivatives. They might even be kind enough to let me use their PCB printer stuff, I'm chatting to a lecturer now.
Now, onto all that stuff you guys gave me. Huge thanks Jaycee, that info was really useful. I'd built PS's, but never with the coils; I'm actually going to apply that very principle to a PS im building for this semester's design project, rack up a few design marks. As for biasing, I did a whole course on DC biasing of BJTs, and quiscent points and all the rest, but that biasing circuit had me buggered, things a lot clearer. As for that thermal feedback, never would have guessed that, this amp impresses me more and more, im presuming it works by heating the resistor, changing coductivity and altering current appropriately? Anyway, lots to consider.
Nordic, do you think its perhaps a better idea if I build the DXamp instead of the HRII, as this is my first amp? Or should I cope with either? As for the PS, my friend and I had discussed using two circuits earlier that day, just wanted to ask and see what you guys had to say about it. I'll ensure I stay away from the mantech trans, it shouldnt take too long for me to source a worthwhile distrubuter.. unfortunately, my varsity works through mantech, so I cant order through them.
I'll take a look at that book too, unfortunately purchasing a book from overseas is a mission sometimes, I'll check out shipping prices, but It'll definitely help in all my future audio endeavours.
Thanks a lot guys, I'll keep you informed on developments, should get the amp built at least within the next two weeks, put some photos up, even if getting the transformer takes a little longer
Now, onto all that stuff you guys gave me. Huge thanks Jaycee, that info was really useful. I'd built PS's, but never with the coils; I'm actually going to apply that very principle to a PS im building for this semester's design project, rack up a few design marks. As for biasing, I did a whole course on DC biasing of BJTs, and quiscent points and all the rest, but that biasing circuit had me buggered, things a lot clearer. As for that thermal feedback, never would have guessed that, this amp impresses me more and more, im presuming it works by heating the resistor, changing coductivity and altering current appropriately? Anyway, lots to consider.
Nordic, do you think its perhaps a better idea if I build the DXamp instead of the HRII, as this is my first amp? Or should I cope with either? As for the PS, my friend and I had discussed using two circuits earlier that day, just wanted to ask and see what you guys had to say about it. I'll ensure I stay away from the mantech trans, it shouldnt take too long for me to source a worthwhile distrubuter.. unfortunately, my varsity works through mantech, so I cant order through them.
I'll take a look at that book too, unfortunately purchasing a book from overseas is a mission sometimes, I'll check out shipping prices, but It'll definitely help in all my future audio endeavours.
Thanks a lot guys, I'll keep you informed on developments, should get the amp built at least within the next two weeks, put some photos up, even if getting the transformer takes a little longer
Jonathan Turck said:
Actually the heated part is the BD139 transistor that makes the bias servo. This causes it's conditions to change which regulates the current. This is why a BD139 is used - the TO-126 case is ideal for thermally coupling to a heatsink.
Sometimes you also see a string of diodes used, and the principle is similar - the heating causes the voltage drop of the diodes to change, and this controls the current. As an experiment, take a 1N4148 diode, and put it on your multimeter's diode test. Now, warm the diode - the heat from a lamp will do. Notice what happens on the meter
Hi J, yep the DX is much easier to assemble, allthough it has an extra control to adjust the DC offset... just buy a few extra BD139 and 140 because you will likely fry one or two on your first build... (I know I did)...
DX is more powerfull than the HRII, but slightly less detailed.... there is definatly a large part of people who will like DX more than HRII, especialy at a party... it does not have a peak in bass frequencies, but it "extends" bass notes, makes them feel a bit longer...
It will dance circles around a gainclone both in respect of power handling (100W into 4 ohms) and sonics...
DX is more powerfull than the HRII, but slightly less detailed.... there is definatly a large part of people who will like DX more than HRII, especialy at a party... it does not have a peak in bass frequencies, but it "extends" bass notes, makes them feel a bit longer...
It will dance circles around a gainclone both in respect of power handling (100W into 4 ohms) and sonics...
Aight! Im on; I'm going the plain old DXamp way; my dad has offered to fund most of the amp, if I build him one sometime during the year; I'm thinking I'll leave the HRII til then, build him something pretty.
I'll be sure to get a couple BD139s, i presume thats just messups in the biasing? Also, which is more recommendable; building the bias on a little PCB, or on a punchboard? Nordic, where did you get those power transistors from, I cant source them from anywhere other than mantech?
I'm using the PCB printing labs at my uni to make the boards, so I'm getting them done nice and cheaply; the rest of the components I'm picking up during the week, i'll throw some photos up when I get a channel built. Thanks guys!!
I'll be sure to get a couple BD139s, i presume thats just messups in the biasing? Also, which is more recommendable; building the bias on a little PCB, or on a punchboard? Nordic, where did you get those power transistors from, I cant source them from anywhere other than mantech?
I'm using the PCB printing labs at my uni to make the boards, so I'm getting them done nice and cheaply; the rest of the components I'm picking up during the week, i'll throw some photos up when I get a channel built. Thanks guys!!
Alright, a problem with the PCBs: My university technicians will print the boards for FREE! And do all the drilling, etc. Well not quite free... They asked for the donation of a cake to the tech department, I'll argue not. One problem; for whatever reason they need the PCB original file; an Ultiboard or similiar PCB development file, its something to do with the software they use to produce the boards. Are those files available anywhere, or do I need to figure out some way to develop them, like laying out the circuit and developing my own PCB? I've checked Greg Erskine's site, only the .jpg, which is unfortunately not enough. Help!
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