AceBass up and running

AceBass circuit on small PCB

AceBass circuit on small PCB

Finally got the PCB for my AceBass circuit populated with components. It has been in my drawer for some time, but now it is time to do something about it.

…. and it actually works like a charm.

I used my small 6.5″ Peerless woofer (which I use for my PC as sub) just for the initial trails, just to test out the concept:
I have the driver in a small 11 liter closed box, which has been used together with a Linkwitz Transform circuit.

After some calcualtions and some simulation in WinISD, I decided for the following parameters:
Parameters before:     With AceBass:
Cms = 1.0166
Mms = 18.5
Rms = 1.5239
Fs = 36.7
Qts = 0.59
Vas = 28.5
  Cms = 0,6
Mms = 80
Rms = 30
Fs = 23.0
Qts = 0.32
Vas = 16.8

Don’t think you will find a driver with these parameters in real life 😎

In the WinISD simulation below  it is seen how the driver now goes down to some 28 Hz before rolling off. The green line is with the AceBass circuit, the yellow is without.

WinISD with and without AceBass

The circuit it self is almost identical tothe one showed in AES paper by Karl Erik Ståhl, but with values calcuated to fit the small Peerless driver:

AceBass Schematic

AceBass Schematic

You can also download a pdf version of the schematic here … it’s a bit easier to read.

For the calculations I used a small Excel sheet, which can easily be used for calculations for other drivers .. download it here and a tutorial or step by step guide here




Here is a picture of the small subwoofer. The vent used is 4 cm wide, and 34 cm long, so it needs a bend in the box to fit …. until I get that it has to just point out of the box!

IMG_0596 (Large)


So what is the conclusion?

Well, it works, and the small peerless wofer now goes down to 28 Hx in a quite small box. The circuit needs a little more amplification, as the sub is now a little to week in amplitude with the small 2 way speakers I use. This should be easy to fix (fixed by changing R13 from 22k to 10k). Otherwise I think I’ll try it out on some larger speaker as well, and with a larger amplifer. The one I use is just some 25W. I will also have to do some measurements to verify that it actually works as prescribed. But this is a good first step 😉

14 comments to AceBass up and running

  • båndsei

    Congratulations.I have been watching this site to see your progress with the ACE bass system.To me it does not seem to be that easy to make I i have seen your exel sheet and have at least one question.Can i use your values for the wanted parameters of the “ace bass”?

  • admin

    Hi båndsai

    Well I think it needs a bit more explanation … sorry. I have placed a step by step pdf here, which I hope explains it a bit better … otherwise make a comment again :)

    /Baldin

  • frank

    i am interested to ace bass, I’m trying to simulate a 2-way speakers with ace bass using speakers ciare (hw159 and ht263) and the frequency cut-off of 2KHz, is possible?
    i have 2 questions:

    1) but the amplifier is inverting or not ?
    2) in the schematic P6 (overload) where is connect ?

    I find an evolution of acebass (free pantent 4,797,933) where compensation also the Le of Louspeaker, i ask to you is better?
    thanks a lot for an answer

  • frank

    Congratulations on the job, I’m sorry not made in the previous mail.
    the speakers are the CIARE. I try to reduce the volume from 32 to 13 liters, is it possible?
    I’m reading the article, but I do not understand how to make the new values (aca bass) of CMS, RMS and MMS for the alignment type B4.
    Furthermore, the pattern of the PCB is available?

  • admin

    Hi Frank
    P6 is just if you wan’t an off board diode for showing overload.
    I don’t know this particular patent, but with the showed circuit, you will not be able to use it for midrange. Don´t go higher than like 500 Hz. Therefore It’s really not suited for a 2 way speaker, but intended for a sub.
    Use WinIsd for simulating the chosen speaker unit with the new parameters and find find an alignment (freq shape, group delay and impulse response) you like.
    Kind regards Baldin

  • franco

    Is possible to use it for closed box ?

  • admin

    Hi franco
    No, AceBass is for ported or passive radiator design only. For closed box design use a Linkwitz transform circuit.
    Best regards Baldin

  • tcli

    Very interesting work.

    I’m surprise of your answer about closed box.
    From what I understand from the patent, ACE-bass allows to virtualy change T/S speaker parameters.
    So, It could be used for closed box too…

    Will you make your PCB available somewhere ?

  • admin

    Hi tcli

    Think you are right, it can also be used for closed box.
    But it wil easier to use an LT.
    Anyway, I think the AceBass is really smart in the way it can be used in a ported enclosure … you get a lot of extra low bass for almost free, compared to a closed box.

    But used in a closed box you of course would still get the benefit of the feedback and therefore lower distortion.

    Best regards Baldin

  • frank

    The ampli connected to P2 must be inverting or not ?

  • admin

    Hi Frank

    The amp should be non-inverting.

    The opamp U3A is there to invert the signal.
    If you use an inverting power amplifier, you can ommit U3A.

    Best regards Baldin

  • admin

    Hi tcli
    Regarding PCB files. Here they are, in gerber format.
    http://www.sensibleaudio.dk/AceBass/AceBassPreAmp.zip

    You can either use a gerber viewer like GC-Prevue (which is free) or use the files directly for production at a prototype company like Olimex.
    Good luck and keep us posted on results.
    Best regards Baldin

  • […] Never heard of this before… Seems like it's old technology from 1978 Good info here: check the links in my links for .pdf and excel sheets […]

  • Dear Baldin,

    Congratulations with a succesfull implementation of the Ace-Bass concept. I would like to try it myself, have a big issue and question:

    When plugging the T/S values the ACE modified woofer in a 11 litre enclosure, tuning it to 27Hz, LspCAD gives ridiculous and unrealistic pipe lenghts. The rule of thumb has been max 3,5 a 4xdia of pipe.

    How have you managed to solve this problem? By the way, using multiple vents does not seem to work. Modelling multiple (smaller) vents in LspCAD amounts to one big vent with a proportionate increase in length..

    Thanks in advance.

    Eelco Amsterdam-NL

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