D.I.Y. Amplifier - A 200W Class D module amp build for $250 total

Mystic38

Mystic38

Inspired
I wanted to start a D.I.Y Thread for both amps and cabs, so here is the first. DIY amplifiers...mostly because its a great deal easier..lol

I have, in past lives, been lucky enough to work in some fun fields including designing amplifiers and power supplies in the many kW range. I do, however live in the internet so I also probably have a Nobel peace prize so nothing here is a substitute for your own research, using rational sources, and Murphy's law says you will in fact make something not work, or more fun, blow something up and some point in time.

Which brings me to the topic of amplifying our beloved Fractal gear for home and small stage. Yes, you can use Studio monitors, or a PA, or a $1000 wedge or cabinet of some description, but we are in the amps and speakers room so here goes.

For the last 3 years I have been using my Genz Benz Streamliner 900 bass amp for this purpose via the aux in. It has prodigious power reserves, sounds musical and is clean and flat a response as you could possibly wish for. It however, sits atop a 212 cabinet and I wanted to end up with a powered cabinet, and so, not wanted to dedicate a $$ bass amp to the purpose I started to ponder a replacement.

I started to consider a design using a plate amp.. a popular approach, but not the cheapest, and using a full range speaker like the F12-x200 or F12M-150, the extra filter functions was just not needed, however if you want it to be a mixer with extra inputs, its a good choice. I wanted to begin at the lower end of $$$ so I started to look at Class D modules. Note that to make a Class D amp work, you need both a power module and a power supply, and they are not always bundled together.

Initially I researched the Hypex nCore 500.. a phenomenal amp that I am familiar with as it is embedded into several audiophile grade amps costing $$4k & up.. but a design for these would be rather costly and its unclear that the benefits would justify the extra cost. I settled on an IcePower 200ASC that provides 200W into 4 Ohms. for $130. An alternative would be the IcePower 50ASX2BTL, which is the 170W module inside the SD Powerstage 170 for the same price, but note that SD have included an EQ, and are not specifically targeting the PS170 at full range/transparent designs, so it is not clear to me, and i doubt that the default (noon) response is flat.. and that is a requirement for a transparent amp to go with the Fractal gear.

If you are planning on a powered cabinet build the parts list for the amplifier section amounts to about $150 and is simply the following, all from parts express (USA, sorry)

1 IcePower 200ASC Module (integrated amp + power supply)
2. Ice Power 200ASC wiring harness
3. A panel mount XLR socket
4. An IEC receptacle with on/off switch

For my purposes, I also purchased from Ghentaudio.com a DIY case kit for this module ($115) , as my cabinet is going to undergo several transformations... but still its a $200W standalone amp for < $250

Build details to follow..
 

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part 2 : Build Notes

First, let me explain that these amps are power amps. There are no pre-amp functions such as volume or tone controls.. put a signal in, get power out and thats it. It is a minimalist design that offers exactly what a FM3, FM9 or AXE-FxII needs and nothing more. Your volume is the volume knob on the Fractal unit and the tone control is your output EQ... but you should not need it for the amp, as it is clean and transparent. You may well, however need it for your cabinet, but that is the upcoming DIY Cabinet thread.

If you wish to make a standalone amp that can sit on a cabinet, or on the floor and plug into a speaker then I would advise the DIY case kit from Ghent Audio, but if you (for example) have built a Celestion designed cab for the F12-x200 and want it to be a powered cabinet, then you do not need anything other than the parts listed above.

There are two documents of use on the parts express website, the most useful is the datasheet which describes the pinout and functions of the connectors. its a must read

https://www.parts-express.com/pedoc...ith-power-supply-module-1x200w-data-sheet.pdf

1. Powered Cab
a) This is slightly more challenging than using the DIY case kit from Ghent, but not seriously so.. anyone with some soldering and basic mechanical skills can undertake this.

b) I would recommend making a new back panel for your cabinet out the appropriate thickness ply as you will need to make a cutout for an IEC switched socket , and a panel mount XLR socket. If you are adventurous, you could buy a LED to wire up and drill a small hole in the baffle to indicate power status.

c) a power amp module should be vertically mounted to aid airflow, so the side or back of the cabinet is slightly preferable to the floor, but in reality dissipation would only be a real issue in a very small enclosed space.. think tiny floor monitor, notsomuch a regular sized 112 or 212 cabinet., so if you want it on the bottom inside the cabinet it will be fine. Just leave enough cable length that you can take the back off and unplug power and signal easily for access.

d) All cables need to be full twisted to reduce EMI. This is not an option working around a class D amp due to the very high switching speeds, so twist the wires up good, and route them aroud the module, not over the top..ie avoid all the switching devices and the field from the transformers..which is probably at 150-200kHz (no idea, a guess). So input cables, signal cables, wiring to speakers and LED wiring should all be tightly twisted.. cehck the photo in the above post.

e) Read the literature, read it again, and double and triple check the wiring for your IEC and XLR connector so that a) you power it up, and b) you actually get a signal.

f) consider how you will mount your module. Best practice would be a thin aluminum plate with standoffs.. this plate will become a ground reference, to which the mains earth and module ground plane is connected... Make this oversize so you can mout the module to it, then screw this plate to your cabinet.

g) Note that there is no ground reference on the output (power) side of a class D module, it is referenced solely to the power supplies and the ouputs are floating. I will make it simple : the speaker has zero reference to ground.. if you ground a speaker terminal, buy a spare module.

What HAS to be connected?

1. P1 : AC Header
Connect Mains Input Line & Neutral input to pins 1 & 2 respectively

2. J2 : Speaker Header
Connect output +ve and -ve to speaker terminals

3. J3 : Signal Header
a) Remove terminals 1-5. Using a very small flat blade screwdriver, in turn lift the plastic tab holding the crimp in place and withdraw the connector wire.. do not pull on the wire before lifting the tab.
b) Connect Connect Pins 6,7,8 (GND, V-, V+) To your XLR Connector Pins 1, 3, 2 Respectively.

4. J4 : Auto Start
Using the header, connect pin1 to pin 2 to disable auto start.

5. LED Output (optional)
Connect Pin 1 and Pin 2 to LED and GND respectively . Remove crimp 3

Soldering tips

If you do not have a powerful soldering iron, do yourself a favor.. get something approaching 100W as a smaller iron will take forever to heat up a large mass of connector, like a speaker terminal.. I bought one, then an aditional two, of these

soldering iron

Summary
In reality the most time consuming part here is the mechanics.. getting standoffs, your baseplate, and cutting access holes in your rear panel and mounting the connectors.. The electronics connections (above) is by far the easy part... and if the module is mounted close to the IEC and XLR input sockets you will not need additional wire.
 
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The Icepower amps look ideal for diy builds, with the integrated supplies and wiring harnesses. I was exploring that option and then spotted a Crown amp listed local for a good price. I built a combo of sorts, an F12 cab with a rack mount below for the Crown. It’s a tank though, so I’ll keep an eye on your progress, and maybe do it myself.
 
I looked at the Icepower amps, but wound up with a Dayton plate amp in a Celestion F12 DIY cab. The Dayton isn't cheap, and it's pretty inherently noisy; lots of hiss. I set every EQ program to flat to ensure there's no inadvertent wrong setting at a gig. Works great though - plenty loud, and self-powered cabs keep the equipment load in check. I have a pair if I need them. The F12 sounds and feels great, I'm very happy with them for my use. A cab or two onstage to supplement and liven up IEMs and/or wedges, and let FOH take care of the rest. Best and most manageable tone I've ever had.

As a retired engineer myself, I got a kick out of your write up. I re-drew Celestion's minimal plans into a 3D model, made some minimal changes (slightly recessed back panel), added all the cabinet hardware mounting details, made a parts list and cutting diagram, and documented how I wired and programmed the Dayton. Old habits die hard.
 
Part 3 : Testing

When you think you have wired it up and its ready, its time to test it..?.. Nope. Go back and recheck every connection, look at the datasheet and double check.. take a break.

1. Check!..Yes, again.
Everyone makes mistakes no matter the experience level.. just try not to learn the same thing too many times!. If you make a mistake, walk away and have a coffee, come back, sit down and do not assume that the module is defective. 99.999% of the time you will have wired it up wrong.

2. Power
No speaker, no signal, just the amp and the mains power. Plug it in, hit the power switch and wait. Nothing?.. excellent. unplug.

3. Signal
Add a speaker, plug in a TRS. On your source device, get some music going, set the source volume to zero, and if its your Axe Fx then set output range to -10dB. Plug the main in, hit the power switch and wait. Nothing?.. excellent. Walk away and leave it for an hour or two. This is you, testing.

4. Sound
Turn up the source level. Sound?.. excellent!.. If nothing can be heard, turn off and unplug everything. Get another coffee (this is you, an engineer now), and go back to #1 above - you more than probably missed something.


Initial Impressions

1. Deathly quiet, no hum, no annoying hiss. The simple approach of this amp is perfect. It offers everything you NEED. The lack of a built in pre-amp for volume and tonal control removes extra opportunities for lowering signal to noise ratio and adding annoying hiss.

2. It sounds good. Totally neutral and so annoyingly comment free. Plenty of power reserves. 200W into 4 Ohm and 100W into 8 Ohm. It can be LOUD

3.Any comparative thoughts between this and my GB900 amp ($950 when new) need to wait until i can match the SPL to within 0.5dB and play pre-recorded material.. its that close in tonal quality.. nothing jumps out at all (particularly components!) Actually boring. it just does its job.


Summary

If you are looking to use one of your existing guitar cabinet/speaker setup and want it to be a powered speaker, then this is a great answer.

Actually, no matter what the question, $150 for 200W at 2 lbs is a great answer

Need a carry amp?.. With the DIY case from Ghentaudio, its 6.25W x 9D x 3H and 3lbs and its still < $250



Drawbacks

This is not a trivial build actually, no directions to speak of, there is minimum support available and Youtube videos are not very helpful.

With care and preparation however, a slow & steady mindset makes this a straightforward build.
 
Subjective comparisons

1. I used the FM9 + DIY amp with (one of) my Dynaudio Contour 30 speakers.. a relatively expensive, highly regarded, sizable, inefficient, set of hard to drive speakers that need 200W & up to come alive but are simply outstanding for music production.

wow, just wow. I needed to set the output range to +4dB on FM9 for the amp & speaker to open up but F me I had the best set of grins for 30mins, flipping presets...just awesome.

For a pure amp comparison, I then played some music direct though the DIY amp, then the same tracks through my Classe Sigma Amp5, a 200W rather expensive audio amp. Yes the Classe was better from a music experience, better transient control, faster paced and more open however the sound is much much closer than the price suggests. The DIY amp is not a limitation in any practical sense for my rig.

In summary, this amp is more than capable of doing the job just fine and the overall tone through my home speaker clearly show the potential for a fractal based rig using this amp.. It sounded superb.

My prototype cabinet is a PRS 212 openback with a brace of F12-x200. I am not dissatisfied with it for guitar work, but playing music is the "tell" so I knew it needs work and I can do better.. now I know how far the amp and FM9 can go so If i can close the gap from this speaker to the Contour 30 by even a third, It will be a great rig...
 
Hey @Mystic38 thanks for posting this. I’m not doing this right away, maybe a year out. I’ll be looking at a wedge design and the F12. Or maybe some other full range coaxial speaker. These powered speakers are expensive and can be built at a significant discount. Plus I like building stuff. So your thread is of great interest to me.
 
I built two of the Ice Power amps into my 1-12 Valley arts cabs (made by Pacific) and they slay!!!
 

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In 2020 (covid) I decided to build a bass power amp with 1200AS1 module, as I found out it's used by a respected digital based (at the time) bass amp manufacturer. I figured I could do the preamp stuff with Fractal. Worked out great. Works for the guitar also, but got to be careful with the power.
 
allenma said:
I looked at the Icepower amps, but wound up with a Dayton plate amp in a Celestion F12 DIY cab. The Dayton isn't cheap, and it's pretty inherently noisy; lots of hiss. I set every EQ program to flat to ensure there's no inadvertent wrong setting at a gig. Works great though - plenty loud, and self-powered cabs keep the equipment load in check. I have a pair if I need them. The F12 sounds and feels great, I'm very happy with them for my use. A cab or two onstage to supplement and liven up IEMs and/or wedges, and let FOH take care of the rest. Best and most manageable tone I've ever had.

As a retired engineer myself, I got a kick out of your write up. I re-drew Celestion's minimal plans into a 3D model, made some minimal changes (slightly recessed back panel), added all the cabinet hardware mounting details, made a parts list and cutting diagram, and documented how I wired and programmed the Dayton. Old habits die hard.
Click to expand...

The Dayton plate was one of my early thoughts, but I ultimately decided to take the cheap and cheerful path with the 200ASC, and I am glad I did. One of the huge benefits of this minimalist design is that the noise floor is stupidly low.. as in, the levels of hiss/hum are so low it is irrelevant.
 
Daveis said:
Anyone sell a kit to construct a Hypex nCore 500 based amp?
Click to expand...
You have to design a build around it and program the DSP ..or design filters.
But they are looking freaking awesome. Hypex kits appear to be more geared toward home audio.

MiniDsp IcePower makes similar Pro level amps.
Its not giant line array level power, but they are both far better than the cheap dayton (ish) plate amps

I think the AS200 posted here is a great affordable option for a monitor. Most coaxial speakers are 8Ω though. These class D amps really seem to prefer 4Ω loads.
 
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Mystic38 said:
I wanted to start a D.I.Y Thread for both amps and cabs, so here is the first. DIY amplifiers...mostly because its a great deal easier..lol

I have, in past lives, been lucky enough to work in some fun fields including designing amplifiers and power supplies in the many kW range. I do, however live in the internet so I also probably have a Nobel peace prize so nothing here is a substitute for your own research, using rational sources, and Murphy's law says you will in fact make something not work, or more fun, blow something up and some point in time.

Which brings me to the topic of amplifying our beloved Fractal gear for home and small stage. Yes, you can use Studio monitors, or a PA, or a $1000 wedge or cabinet of some description, but we are in the amps and speakers room so here goes.

For the last 3 years I have been using my Genz Benz Streamliner 900 bass amp for this purpose via the aux in. It has prodigious power reserves, sounds musical and is clean and flat a response as you could possibly wish for. It however, sits atop a 212 cabinet and I wanted to end up with a powered cabinet, and so, not wanted to dedicate a $$ bass amp to the purpose I started to ponder a replacement.

I started to consider a design using a plate amp.. a popular approach, but not the cheapest, and using a full range speaker like the F12-x200 or F12M-150, the extra filter functions was just not needed, however if you want it to be a mixer with extra inputs, its a good choice. I wanted to begin at the lower end of $$$ so I started to look at Class D modules. Note that to make a Class D amp work, you need both a power module and a power supply, and they are not always bundled together.

Initially I researched the Hypex nCore 500.. a phenomenal amp that I am familiar with as it is embedded into several audiophile grade amps costing $$4k & up.. but a design for these would be rather costly and its unclear that the benefits would justify the extra cost. I settled on an IcePower 200ASC that provides 200W into 4 Ohms. for $130. An alternative would be the IcePower 50ASX2BTL, which is the 170W module inside the SD Powerstage 170 for the same price, but note that SD have included an EQ, and are not specifically targeting the PS170 at full range/transparent designs, so it is not clear to me, and i doubt that the default (noon) response is flat.. and that is a requirement for a transparent amp to go with the Fractal gear.

If you are planning on a powered cabinet build the parts list for the amplifier section amounts to about $150 and is simply the following, all from parts express (USA, sorry)

1 IcePower 200ASC Module (integrated amp + power supply)
2. Ice Power 200ASC wiring harness
3. A panel mount XLR socket
4. An IEC receptacle with on/off switch

For my purposes, I also purchased from Ghentaudio.com a DIY case kit for this module ($115) , as my cabinet is going to undergo several transformations... but still its a $200W standalone amp for < $250

Build details to follow..
Click to expand...
I'm confused as to which kit you got from Ghent Audio. Could you link it please?
 
^^ It all depends if you want a powered cab, or want a standalone amp..

1. I wanted to start with a standalone amp so bought the matching case for the 200ASC, it is this : https://www.ghentaudio.com/kit/a215-m2.html

This case is not perfect for a standalone guitar amp as it has holes for RCA input jacks and an input switch (unused) and of course speaker binding posts rather than a 1/4" socket... it does, however make it quicker to get up and running. If you go this route you do not need any additional items.

a) the unused holes for RCA and switch were filled with the two smallest sizes from this set : Amazon product ASIN B089WGS7WM
b) for the binding posts to 1/4 conversion i got lazy and bourght these : Amazon product ASIN B07T9ZCV78
2. For a powered cab application, there is the easy way, and the cheap way for the amp, but in both cases you will have to decide how to mount the power and signal inlet connectors (certainly nor right next to each other...).. In my case I have been considering (since i don't like destructive testing) making another back panel for my cabinet and hacking that.

a) Lazy/Easy way :
i) Use the Ghent Audio case, mount it to the inside of the rear or side panel using the screw holes for the feet as mounting points and screwing from outside to in... they are threaded in the case so it's "simply" a case of careful alignment of the mounting holes, or
ii) Another way would be to mount the case to an aluminum panel and mount that..

b) budget way :
Get the appropriate standoffs and attach the amp to a plate then mount the plate either internally or as a plate amp.

If you are already decided on it being a powered cab before purchasing, i would suggest that getting a sheet of aluminum to mount the amp module to, then the plate itself is easily attached to an internal vertical panel of the cabinet.. then use the cabinets speaker input plate for the signal input, and make one single cutout for the power inlet... so work will be needed to figure out the dimensions etc of all the standoffs you will need for the amp, but this is straightforward.. will just take some time.
 
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I’m looking into a powered light weight wedge build. The IcePower 200ASC is 200 watts into 4 ohms so into 8 ohms it will be 100 watts. I’ll be using a coaxial Eminence speaker with a passive crossover. Will 100 watts be enough to keep up with a loud drummer and band? I’m guessing it will be since a lot of people seem to be happy with the Powerstage at 170 watts. I figure many of those people are running 8 ohm speakers. I get headroom but todays FRFR speakers seem to overkill it with available power.
 
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