A new concept in amps possibly ?

Danny1969

So I actually had a day over Christmas where I didn't have to make or repair anything for anyone else. So obviously I decided to build myself a Christmas present. Originally it was going to be a basic small class D power amp capable of fitting in a gig bag to act as a backup in case my main amp failed at a gig. Then I thought why not make it stereo, I can use it for other means then as well. Then I thought why not get some DSP in there so it's an amp in it's own right, like a Tonemaster. 

Well as it happens I had a broken Nux mighty plug so I could use the PCB from that. Then I thought every time a new modeller comes out people are essentially buying another box, another PSU, the knobs etc, then got to plug it in to an active speaker unless they are on ears to hear anything. 
Why not build a stereo amp that accepts the DSP side of things in a piggyback plug in form. The amp is a normal power amp for modellers but you can also just plug in a DSP block controlled form a phone and licence the format to third parties ... so people can just code the DSP and put in into a standard plug in block. 
So I started hacking away and within a few hours had this very rough and ready prototype 



So the spec of this things is 

2 X 50 watt stereo amplifier (same kind of modules as Fender Tonemaster but stereo version) 

Mono hi Z input for guitar 

Stereo input for modeller, recording interface etc 

The switch selects either mono in to DSP block to PWR amp or stereo in straight to PWR amp. 

The round buttons are on /off and channel change. 

2 x balanced DI outputs 

Footswitch for channel change 

USB for recording 

Bluetooth 





So this was very easy to do because most of the work was done for me. The Icepower module only needs a 240V connection, 2 speaker outputs and a line level input to work. But is also includes a very useful dual 25V - 0  - 25V aux supply for powering the pre amp and other devices. It's also has a useful enable pin so you can turn the amp on and off with a small switch or a remote receiver. 
All the DSP is in the little Nux PCB. All I had to do was get some IO on the PCB and feed that to the 5 pin socket. 



So this is obviously a very, very rough implementation of the basic idea as I could only build with connectors and switches etc I had in my parts bin. A proper company would come up with a better layout with assignable controls via software and a  professional finish and probably a proprietary connector with more pins to control the DSP block. 

But I think the basic idea is sound .... you buy the one box which is a head and contains all the IO  and when a company develops a new model of an amp they can just sell it to you in the DSP block .... that way you could have a few different DSP blocks from different vendors and simply plug the one you think is most suitable for the gig ahead. 

I'll try and get some video up on YT over the next few days so you can hear it. I also took some amature video when I was building it explaining how to go about using the Icepower modules in case anyone wants to have a go themselves 

Moe_Zambeek

Looks interesting. Similar concept to the ‘tone capsule’ from Roland / Boss.

Fez

Sounds like a brilliant concept, I think there were similar modular valve based amps in the past IIRC Dean Markley did one. This sounds like a better prospect though. Very interested to hear the result.

CarpeDiem

Sounds like a great idea, and what an excellent Christmas project. I don’t know if there’s any standardisation in DSP formats, although IR’s seem to be a uniform format, but it would be great for consumers if there was. I’d suggest approaching some of the manufacturers to gauge their interest.

Supportact

Looks like a very good idea. The only downside I can see is that the various proprietors of the DSP blocks are probably counting on people buying their hardware each time, so they might not cooperate. Very clever idea though! 

ICBM

Great concept - although the problem is likely to be getting an industry standard on what you can download to the DSP unit.

I had an idea a while back for a 'universal pedalboard' like this where the board itself was just a switching unit and contained about a dozen DSP blocks with assignable controls, which you could download effects from an 'App Store' to - I asked a person in the music software industry who some of us may know - whether it was feasible, and that was basically the answer - all the companies want their own proprietary system to lock users in.

digitalscream

Yep - I seem to recall discussing something similar with Drew, years back. In fact, it's not too dissimilar to the Atomic combos - valve power section, and had physical adapters for most of the modellers of the time (including the POD 2.0!). Obviously things have moved on a long way since then, and the actual hardware required for the DSP is much, much smaller.

The connectors (and physical compatibility) were the sticking point back then, as noted - the digital audio industry is at least a decade behind the PC industry, and still seems to believe that proprietary hardware is the best way of protecting themselves instead of using consumer-friendly standards.

One thought: an interesting way you could use this is with a Pi 5 and the NAM profiler...?

andy_k

digitalscream said:

One thought: an interesting way you could use this is with a Pi 5 and the NAM profiler...?

I immediately had that same thought, seeing as I treated myself to a Pi5, and am just waiting for the case manufacturers to come up with something good, there are quite a few Pi4 cases now available with a 3.5 inch touch screen attached, which would be great if they could simply display and control the NAM plugin window- far beyond my own programming capabilities just now, and the Pi4  has audio output built in, which has been dropped on the Pi5, for some reason, plenty of USB ports though.

Stratavarious

Neat.. like the Seymour Duncan Convertible with swappable preamps.

DartmoorHedgehog

Nice project. But (and this isn't meant as a put-down at all) what do you see as the advantage over having a stand-alone stereo power amp and using it to amplify various little modelers? I can't see people selling modules for less than the price of a NUX, Vox Amplug etc, and having the actual amplug would seem more versatile.  Not quite as tidy though I suppose.

hollywoodrox

That’s so cool, well done 

Danny1969

DartmoorHedgehog said:

Nice project. But (and this isn't meant as a put-down at all) what do you see as the advantage over having a stand-alone stereo power amp and using it to amplify various little modelers? I can't see people selling modules for less than the price of a NUX, Vox Amplug etc, and having the actual amplug would seem more versatile.  Not quite as tidy though I suppose.

Oh the idea isn't a power amp for headphone amp plugs  .... it's for full blown ARM DSP. I only used the DSP from a Nux MP2 because I had a broken one to hand and I lack the skills to build and code DSP for a full blown ARM architecture powered DSP block.  As it happens I really like  the Nux models  despite the much lower processing power of the Nux PCB compared to the big boy modellers. 

Think of it as a Tonemaster (it actually uses the same power amplifier) but rather than having one built in DSP option like a Princeton Reverb,  the DSP is built into a removable and swappable module ... so the one amp can be a Princeton or a Marshall or a Vox AC30 ... the module can also contain any effects the coder deems useful like reverb / delay etc. 

Then of course it's also a linear stereo power amplifier that can amplifier your Kemper  / Helix / Quad Cortex in stereo 

So I imagined the user had the head and then brought a module containing the Helix amp models. Then the user brought another module containing the Quad Cortex amp models. And so on ... 
So basically it's like a Nintendo cartridge console but for amp sounds

Now I know in the real world there's no way this would happen. Everybody will want to protect their intellectual property, code wise  and not let it be used on any other device but their own and I get that. 

But, once you have a device to code for and you don't have to build anything, well.. that opens the door to all kinds of developers. Basically opens it up like the plugins did for the DAW market. 

I just like building stuff but it has to be stuff that's a bit forward thinking to interest me. have no appetite to do any of the stuff mentioned above  myself but enjoy speculating what is possible. This was a very quick project, just a few hours in drilling, bolting  and soldering but I plan another version soon which will look a lot more professional rather than workshop lash up



 

DartmoorHedgehog

OK, so a bit more like the Randall swappable-preamp heads but with digital preamps.  So you're imagining people would think of it more as a "head where the preamp could be upgraded/changed" rather than a "power amp to amplify various small modellers". I think I'm having trouble separating the two in my head - I keep coming back to the "but if I had the actual amplug I could use it on its own as well instead of having to use it with the head" - but I suppose theoretically the modules could be more powerful than the little amplugs.

If the DSP section was part of the head as well then people could just upload new software - but then I suppose it would just be like any other modeller with upgradable firmware (except that it could be made open-source rather than bespoke to one company). The DSP needs to be in the removable module to allow the concept to grow with new/different DSP technology. But then I'm back to thinking why not just plug the POD/Helix Stomp/whatever little modeller into a power amp? Your idea makes for a tidier solution though if people were prepared to release their modellers in plug-in module format.

Anyway, I completely empathise with the "making stuff because it's possible" attitude   I'm just being devil's advocate really.

maharg101

Foxrox Zim on steroids. A good concept. Interested to see where it goes.

stickyfiddle

@DartmoorHedgehog I was just reading all of this thinking about those Randall heads. You could fit up to "4 channels" iirc. 

I'd be well up for this with Vox and/or Plexi option, but understand why that's unlikely. 

Danny1969

DartmoorHedgehog said:

OK, so a bit more like the Randall swappable-preamp heads but with digital preamps.  So you're imagining people would think of it more as a "head where the preamp could be upgraded/changed" rather than a "power amp to amplify various small modellers". I think I'm having trouble separating the two in my head - I keep coming back to the "but if I had the actual amplug I could use it on its own as well instead of having to use it with the head" - but I suppose theoretically the modules could be more powerful than the little amplugs.

If the DSP section was part of the head as well then people could just upload new software - but then I suppose it would just be like any other modeller with upgradable firmware (except that it could be made open-source rather than bespoke to one company). The DSP needs to be in the removable module to allow the concept to grow with new/different DSP technology. But then I'm back to thinking why not just plug the POD/Helix Stomp/whatever little modeller into a power amp? Your idea makes for a tidier solution though if people were prepared to release their modellers in plug-in module format.

Anyway, I completely empathise with the "making stuff because it's possible" attitude   I'm just being devil's advocate really.

Well the Nux is still fully functioning ... it's just the input connector is different ? I can still us it as an recording interface, 

Going back to the Nintendo comparison .... it was much cheaper for a company to buy a blank cartridge and code in their Mario or whatever without having to build a console and supply it with firmware and DSP that could take the Mario code. 

There's a similar thing in studios called the lunchbox format. You buy great compressors and EQ's etc on a card and they slide into the lunchbox which has all the I/O

@stickyfiddle 

I can easily do a mod kit for Tonemasters as the I/O headers with Enable and PSU pins of the Icepower blocks are available pre harnessed so the user wouldn't even need to touch a soldering iron 

Danny1969

Had a little play through it today. I purposely bypassed the pre amp stage to keep the wattage down as the fan isn't fitted yet. The hole on the lower right is for my temp probe to enter so I can see what the temperature is like with the lid on and no fan. Once I know that I know what size of fan I need. After 2 hours it was 40C so will need a fan for full power. 

barrettisgold

Great idea, BYO DSP. Top playing

Danny1969

barrettisgold said:

Great idea, BYO DSP. Top playing

Thanks man appreciate it

So version 2 will now get underway. Slightly bigger box and post DSP hardware EQ. As the DSP block needs more IO I will probably switch to a D-sub connector which will allow footswitch channel change and pass through of data differential for USB plus extra pins for more versatility in control. 

What's nice is the amp is essentially 3 parts. The power amp which is of the shelf so no effort at all. The DSP module which can be worked on and tested as a stand alone device and a simple buffer - post DSP tone control - headphone amp PCB which I can build on one piece of veroboard,  with the design greatly simplified because the power amp module has the dual aux supply. This means the opamps can be used DC coupled with no input bias. 

The first prototype will be kept as is ... to be honest I love it as a little home amp so it will get used a fair bit. Plus it fits in my gig bag so is a nice backup amp in case my Hot Rod dies mid gig. 

digitalscream

Danny1969 said:

So version 2 will now get underway. Slightly bigger box and post DSP hardware EQ. As the DSP block needs more IO I will probably switch to a D-sub connector which will allow footswitch channel change and pass through of data differential for USB plus extra pins for more versatility in control. 

Is there a way to use something like RJ45, to fit more closely with the modern connector set? I get that it's less structurally-sound, of course.

In fact...thinking about it, letting the DSP block handle all non-audio I/O itself might actually be more future-proof by being less prescriptive (you just know somebody's going to want more than you provide). Hell, it could even handle multiple audio outputs that way, so you could have an entirely different signal path out to the desk compared to what's going through the amp. It would also allow you to keep the more structural XLR option.

Danny1969

digitalscream said:

Danny1969 said:

So version 2 will now get underway. Slightly bigger box and post DSP hardware EQ. As the DSP block needs more IO I will probably switch to a D-sub connector which will allow footswitch channel change and pass through of data differential for USB plus extra pins for more versatility in control. 

Is there a way to use something like RJ45, to fit more closely with the modern connector set? I get that it's less structurally-sound, of course.

In fact...thinking about it, letting the DSP block handle all non-audio I/O itself might actually be more future-proof by being less prescriptive (you just know somebody's going to want more than you provide). Hell, it could even handle multiple audio outputs that way, so you could have an entirely different signal path out to the desk compared to what's going through the amp. It would also allow you to keep the more structural XLR option.

Mmm well RJ45 in a Neutrik D shell is an industry standard connector ... it's what interfaces digital stage boxes to digital desks so it certainly is an option and actually easier form my perspective as it uses a standard XRL cut out. 

What I see achievable in terms of what I can do is a generic DSP PCB with it's own AD and DA fitted into my module design and then programmed by someone who knows a lot more about that side of things than I do.