Ambrosi Amps' K-Power Amps - Retrofit poweramp solutions for the Lunchbox - With pictures & videos

    Quote from viabcroce

    Andrea Ambrosi Himself is coming to my place from the East coast to install and measure the prototype on the field and compare it with the CLR


    Interesting project !


    One thing I do not understand :


    Why compare it with a CLR ?
    I thought a small power amp like that is supposed to drive a traditional cab ?
    Even if it drives a FRFR cabinet , that FRFR cab will have some sort of crossover network in it.
    You could compare your amp with another pure power amp (say a Matrix or even a Camplifier) on that FRFR cab, but comparing it to an active CLR is like comparing a Cesna to a Boing 747.
    The active CLR has active crossover networks inside and uses bi-amping (one amp for the mid, one for the tweeter).


    Do I miss something ?
    To me that comparison makes no sense at all....


    Good luck!
    Tilman

    Andrea has arrived a few hours ago.


    With the poweramp trimmer set halfway I couldn't go over 2/10 with the Profiler's master. And we were using the cab @ 16 ohm, the highest impedance (and lowest volume).
    The maximum measured power on the amp was about 3 W at that stage.


    If I had raised the volume further, my neighbours would call the cops LOL


    Don't really believe I'd ever need more power. I can still go 8 ohm and then 4 :thumbup:
    :D

    Quote from Ingolf

    How does your Mesa cab sound, the first time without its head?


    Oh, it's not a Mesa cab, it's a Dragoon (see both here). Well, after one year of CLR the cab (very good in itself) sounds boxy, a bit dark and woody :D But the powered Profiler + the Dragoon weight 20 kg together, which makes for a very light setup I can carry at once (guitar included) :)



    Quote from mbenigni

    So jealous - we all need friends like yours! What's the probability he'll build or ship more of these?



    We're seriously consider this. We'll make a decision after the extensive testing I'll be performing in the following weeks, and once it becomes clear to him how to conveniently find the needed parts and the manufacture (for the aluminium plate).
    Also, keep in mind that he's not "a firm", but more like a luthier
    The initial project has been improved and made more powerful, with a 65-W amp and a 100-W transformer (traditional, non the switching kind).


    I'll post some pictures in the next days, and a video when Andrea edits it.


    PS: With the power trimmer halfway, I set the Profiler's Master volume all its way up... and the noise the guitar made when I just raised my fingers from the fretboard was unbearably high... I could not stand it.
    With the Master @ 2 the amp output about 1 W, and there were the expected 102 dB @ 1 m. So far, so good :D

    Quote from Ingolf

    The Camplifier series is readily available.
    What keeps you from using these right now?


    I could sell 20 or 30 Camplifiers in a few weeks, maybe more...I think they're brilliant...TOP product!
    Problem is, exchange rate between the SA Rand and Euro makes it too expensive.


    I'm betting if this poweramp Gianfranco is now testing makes it to the commenrcial market the 150 Euros will turn into 250 Euros when final calculations are done...good price maybe in Europe, buy too high in SA, unfortunately. :(

    Quote from Guitartone

    I could sell 20 or 30 Camplifiers in a few weeks, maybe more...I think they're brilliant...TOP product!


    Thank you very much !


    I don`t know about the SA Rand, but the Euro is going down, and down ...and down......:-(.


    Bad for us, good for people outside of Europe.


    If you were to take 20-30 Camplifiers, you would certainly get a very good price for it ! :)


    Tilman

    Quote from Guitartone

    I'm betting if this poweramp Gianfranco is now testing makes it to the commenrcial market the 150 Euros will turn into 250 Euros when final calculations are done...good price maybe in Europe, buy too high in SA, unfortunately. :(


    I'd still gladly fork over 250eur instead of 400... 8) It's pretty much a difference between me having a poweramp for my toaster and me not having a poweramp for my toaster. :rolleyes:


    I'm really hoping this sees the light of day, if only in limited quantities for the forumites.

    I'm just trying to be as truthful to my experience and personal opinion that I'm clearly presenting only as a personal opinion no more no less in an honest and truthful discussion about equipment.

    Quote from DangeRuss

    I'm getting excited about the prospects. Thanks for the updates!


    :)


    Andrea has just left the building :)


    We shot some videoclips but, as I have always believed, the sound we heard in the room was not even similar to the recorded one, if you use inbuilt mics. At least they should be heard through a quality audio system (even headphones if they are good enough).


    I made some noise with a G&L Interceptor, a guitar which is extremely bright and powerful at the same time for a strato. As usual, my other guitars sounded way differently through the Profiler.
    Anyway, the general consideration is that this amp is extremely linear, and it adds no meaningful colouration to the sound. Furthermore, its input sensitivity was set halfway, to allow the use of higher values on the Master Volume (seemed just practical).


    I recorded some notes with the Master set @ 2, 3, 4 and 5 and the cab impedance @ 16 ohm.
    Then I went back to 2 on the Master and switched to 4 ohm on the Dragoon: the noise in the room was almost equivalent to Volume @ 5 and impedance @ 16: I couldn't play any louder, sorry guys :D


    I can't see how this little amp can't be loud enough when used in conjunction with a cab gifted with a good sensitivity.


    Here follows the cab's datasheet for a correct interpretation of what you will hear:


    Quote

    Celestion Century neodymium 102 dB 1W @ 1m, 80Hz-5KHz, 80 W nominal per transducer. Adviced amp: no more than 200 W

    dB(1W @ 1m) 102dB


    Resonance peak 80Hz




    Quote from Guitartone

    I'm betting if this poweramp Gianfranco is now testing makes it to the commercial market the 150 Euros will turn into 250 Euros when final calculations are done...good price maybe in Europe, buy too high in SA, unfortunately


    Andrea is trying to keep it under 200 € actually. A further possibility could be to send the parts and have them assembled locally. But let's talk privately about this if you're interested.






    Quote from Ingolf

    Gianfranco, do you have some pics how it looks like in the back of your profiler?
    Also I had forgotten about your cab, yes, Dragoon it was. ;)



    Yep, publishing them in minutes :)


    This is of course a prototype, the aluminium finish is temporary (too bright and shiny for my taste and for the matte finish of the Profiler. Furthermore, the plate has been cut by hand, while in a chain production it would be cut by a laser.

    Quote from MuddyFox

    I'd still gladly fork over 250eur instead of 400... 8) It's pretty much a difference between me having a poweramp for my toaster and me not having a poweramp for my toaster. :rolleyes:


    This was basically the idea that moved me: with a good cab efficiency I can't believe I'll ever need any more SLP. This project is much easier that a class D amp with switching power supply, parts are cheaper, the assembly is very simple.
    This is and will anyway remain a hand-crafted piece of work, both in good and bad :)

    Edited once, last by viabcroce: typo ().

    Quote from viabcroce


    Andrea is trying to keep it under 200 € actually. A further possibility could be to send the parts and have them assembled locally. But let's talk privately about this if you're interested.


    This is also very appealing. I'm into DIY somewhat and while I never actually handbuilt a tube amp (those voltages scare the bejesus out of me and I know a thing or two about voltages), I do build all my pedals myself. This would make a nice project if complete units ultimately prove to be too scarce or expensive.

    I'm just trying to be as truthful to my experience and personal opinion that I'm clearly presenting only as a personal opinion no more no less in an honest and truthful discussion about equipment.

    Quote from DangeRuss

    It looks good to me already!


    Yep, the main differences will be in the aluminium finish (? I mean its surface treatment) and in the labels which will be produced in a professional laboratory. And the "prototype" sign will go of course :D


    You can open the image to see more details, I've uploaded it in high resolution.
    Note there's also an output for using the Monitor out w\o having to disconnect the K-Power. Now I've connected the two units with a 20-cm stomp cable, and plan to leave it there.


    One of the things I like in how Andrea works is his maniacal way to address a design and issues. This amp is crammed with security devices, fuses, thermal sensors, trimmers, standbies (?)... lot of engineering for such a simple idea.


    Quote from nightlight

    Eagerly awaiting the video. That looks quite nice.


    Andrea is currently cutting it. I was quite disappointed by the results, room mic'ing is definitely not the way to go for evaluating audio, unless of course you use pro stuff and you know how to mic and treat the room. The recorded sounds are no way rendering the experience we had in the room.
    So just expect some chats, some noise and some introductory facts.
    Moving from this, rather than showing the K-Power sonic qualities I tried to focus on the sound levels.
    The first part has been shot with automatic gain to try and make words and sounds better perceivable. Then we switch to fix gain and I progressively raise the volume. I also tried to talk while playing, so you can have an idea about the sound level. My suggestion would be to raise the volume until you have the idea I'm talking in the room, and keep it there while I go.