The XKitz at least has some provision for adjusting levels, which is crucial. The parts look pretty cheesy. Filter caps appear to be ceramic, which is a recipe for disastrously awful sound, and the resistors don't look so good either, probably cheapest Chinese metal films. Even the RCA's look like ten cent junk. If you're interested in fidelity, this is not the way to go. If you just want a cheap toy to play around with and learn something, it might be worth it.
The KMTech looks to have slightly better components, and I can see bypass caps near all the opamps. Probably has polyester filter caps, which are second rate but better than ceramics. Uses all OPA2134 opamps, which will muffle highs but at least provide decent midrange. The PCB layout looks awful, with very little effort put into reducing loops. Again, ten cent RCA's.
Your choice of audio poison...or look into Elliott Sound Products, designed by someone who cares about what things sound like and wants to help people learn about and enjoy audio. I don't agree with everything he believes, but at least he uses fundamental engineering as a guide.
Peace,
Tom E
The KMTech is an equal component sallen key crossover (same as most). The layout causes no loop problems. The filter capacitors are polyester film. The op amps are good quality. You'll probably find you won't use the pcb rca sockets (don't know why they use them, when are they ever in the right place?). On some of the newer versions there is facility for level adjustment, a pot, but I don't think the output is buffered. Depending on your application this may not be necessary. The ESP design is similar and very good.
Hi drtebi,
Both the KMTech's and XKitz look fairly decent to me.
Agreed that ceramic caps are no good for frequency-setting, and that at least one of those board photos appears to show that very thing. But, it is so simple to replace those, either initially or later, with whatever flavor you want. Important to remember that this is your first active crossover and that building it is part of that valued experience. By the time you've finished one of these and used it for a while, your confidence will blossom, and you'll probably be ready to build your very own, full custom JFET LR4 as built by AndrewT.
Congrats on the Klark Teknik D410. Sounds like you're headed down a path much like mine -- grinding a Urei 527-A since 1975! 40 years ago hardly anybody had even heard of 1/3-octave EQ; today they're still sometimes amazed what it can accomplish.
I predict success.
Good luck,
Rick
Both the KMTech's and XKitz look fairly decent to me.
Agreed that ceramic caps are no good for frequency-setting, and that at least one of those board photos appears to show that very thing. But, it is so simple to replace those, either initially or later, with whatever flavor you want. Important to remember that this is your first active crossover and that building it is part of that valued experience. By the time you've finished one of these and used it for a while, your confidence will blossom, and you'll probably be ready to build your very own, full custom JFET LR4 as built by AndrewT.
Congrats on the Klark Teknik D410. Sounds like you're headed down a path much like mine -- grinding a Urei 527-A since 1975! 40 years ago hardly anybody had even heard of 1/3-octave EQ; today they're still sometimes amazed what it can accomplish.
I predict success.
Good luck,
Rick
The ESP projects are actually quite interesting; The "Project 125" might be the best choice for me—at this point my system is a 3-way, but the woofer cannot handle much (but is otherwise very nice), so I already thought about making it a 4-way system.
But, as far as I understand, Project 125 is the PCB only, correct? I would need to source all the parts myself, and put it together... it's also a 2-layer PCB, which may be a bit more challenging for a beginner(?).
Is it correct that there is a power supply on this board already? So essentially all I would need is two of the PCBs plus parts, a transformer, and a case and connectors?
The Klark Teknik D410 is indeed very nice, and also super quiet. It's a 10-band (or 2×5 band) parametric EQ by the way, not a graphic one.
Read the entire article if you haven't already. Look at the schematics. There is on-board regulation, but no large supply caps. Not sure if you'll need those or can run straight from a transformer. Perhaps all the small caps are enough reservoir. You could ask Rod.
This kit is a lot more complicated than P09, although sonics are no better and possibly a bit degraded with all those pots and an extra gain stage, but certainly has more flexibility and features if you think you need them. (The muting circuit is not really necessary, as you will probably almost never turn the xovers off unless they're wired to the PS of another component. They consume about as much power as an alarm clock.) More parts to buy, more stuff to solder, bigger enclosure required. Tough to screw it up if you can follow directions, but it's possible. Documentation is very good.
A two-sided board is no more difficult to build than one-sided, but it can be a bit more difficult to remove or change parts if you need to.
Peace,
Tom E
This kit is a lot more complicated than P09, although sonics are no better and possibly a bit degraded with all those pots and an extra gain stage, but certainly has more flexibility and features if you think you need them. (The muting circuit is not really necessary, as you will probably almost never turn the xovers off unless they're wired to the PS of another component. They consume about as much power as an alarm clock.) More parts to buy, more stuff to solder, bigger enclosure required. Tough to screw it up if you can follow directions, but it's possible. Documentation is very good.
A two-sided board is no more difficult to build than one-sided, but it can be a bit more difficult to remove or change parts if you need to.
Peace,
Tom E
Yes, it's the PC and instructions only; but all the parts are easily available from Mouser or DigiKey. The two-layer (top + bottom) is no more difficult---this one is fairly easy to assemble. There is power REGULATOR circuitry on board---you'll still need to provide a transformer, bridge rectifier, and large filter capacitors. It's an exceptional board!!
OK, I think I am on the right path then.
So what I need now is a transformer, and a power supply circuit, is that correct?
What should I look for in a PSU and transformer, are there some DIY projects that I could put together for this?
I believe the transformer should be ±25V, and I suppose I can easily find one at digiKey or mouser.
Sorry about all the questions, but being a newbie to building circuit boards, I am a bit clueless at times!
So what I need now is a transformer, and a power supply circuit, is that correct?
What should I look for in a PSU and transformer, are there some DIY projects that I could put together for this?
I believe the transformer should be ±25V, and I suppose I can easily find one at digiKey or mouser.
Sorry about all the questions, but being a newbie to building circuit boards, I am a bit clueless at times!
If you are having trouble putting together a power supply for Rod's P125, then his projects may be over your head---perhaps you would be better with the Xkitz ones because they have all the parts and step-by-step instructions. I like the ESP projects because it allows ME to choose all the best parts for his circuits.
Yes, transformer needs to be around 15-0-15V AC.
Something like this is ideal Power Supply for Preamps
Second that. I use P05 with my P09's and it's a great combination.
If you buy the types of parts that Rod recommends, you will get very good sound. If you are just a little more selective about quality components, you can get excellent sound. Rod doesn't believe in superiority of boutique parts, but a few of them, and best quality opamps, WILL improve the performance of his circuits. But even the most basic decent parts will far surpass any of the eBay stuff.
Peace,
Tom E
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