Yep stock every maxamp ships with a little jumper in the volume connector, this keeps the volume at the max setting when not using a volume potentiometer.
Your wiring looks good, unfortunately..
I thought the MiniDSP was a major improvement, but I'm not sure about this, Saturnus will probably be able to tell you though. Should also increase your battery runtime, as you will be able to create a highpass filter for the woofers, to remove the power consuming lower end frequencies which are inaudible anyways.
If you get a miniDSP, be sure to get your gain structure right, as this is very important with a DSP.
Oh and, twisted wires :
http://en.wikipedia.org/wiki/Twisted_pair
Your wiring looks good, unfortunately..
I thought the MiniDSP was a major improvement, but I'm not sure about this, Saturnus will probably be able to tell you though. Should also increase your battery runtime, as you will be able to create a highpass filter for the woofers, to remove the power consuming lower end frequencies which are inaudible anyways.
If you get a miniDSP, be sure to get your gain structure right, as this is very important with a DSP.
Oh and, twisted wires :
An externally hosted image should be here but it was not working when we last tested it.
http://en.wikipedia.org/wiki/Twisted_pair
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Sure. A miniDSP is an improvement. However, it shouldn't be needed to fix the current issue. I can't help but think that maybe the open cabinet construction which can't be completely air tight is limiting you from getting the last bit of performance.
I also advice to try the old amp again and see if there's any problem then. And basically test one thing at a time until you nail down the cause exactly. Before that, it's pretty pointless to start talking about investing in a miniDSP and extra amp. Not that I'd discourage it in any way but it just doesn't solve the problem you're having. Or at least I can't think of a way it could solve your problem.
I also advice to try the old amp again and see if there's any problem then. And basically test one thing at a time until you nail down the cause exactly. Before that, it's pretty pointless to start talking about investing in a miniDSP and extra amp. Not that I'd discourage it in any way but it just doesn't solve the problem you're having. Or at least I can't think of a way it could solve your problem.
It needs to be tidied up and mounted yet.
Until now, i have not had any problems with my MAX-modules (MAX9709 / MAX9704) concerning the audio-quality, but i would recomment to change the input capacitors of the MAXAmp.
Even if ceramics arent that bad (min. X7R, high voltage rating compared to audio level), you may run into problems by their piezoceramic effects. They tend to be "microphonic".
Ceramics tend to do:
Change value my vibrations (microphonic)
Change value by voltage
Change value by temperature
Change them for i.e.
WIMA MKS4 680nF 63V
or
MKT 470nF 63V
When the MAXamp boards are build straight from the Datasheet (MAX9744), the input resistance will be 20kOhms, thus resulting in a -3dB (lower end) frequency of:
17Hz (470nF)
12Hz (680nF)
The MKS4 i use on my MAX9709 board looks like:
You may also try a 22uH inductor in series (only) with the tweeter, resulting in a lower idle power consumption and less "noise" on the upper end.
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Thanks for the input lads...very interesting.
Saturnus. I'm starting to think that maybe there is not a major problem and what I'm dealing with is differences in input level.
What do you use as an input source?
Also all my audio work of late has been listening to and EQing my large PA system which maybe influencing my expectations of my Boominator.
I've certainly not measured over 100db though but I don't know if I can rely on the SPL figures I'm getting with my App.
Without a more powerful Amp I would expect distortion to start at volume levels above 85%, am I right?
Am I right in thinking that with a DSP I can properly eq the system, getting rid of the very low frequencies and getting the right gains for the tops.
Plus surely having the two Maxamps will significantly improve sound quality and overall performance??
It's very hard to know what to expect, I've only ever heard one other Boominator which belongs to my mate and I helped to build.
Saturnus. I'm starting to think that maybe there is not a major problem and what I'm dealing with is differences in input level.
What do you use as an input source?
Also all my audio work of late has been listening to and EQing my large PA system which maybe influencing my expectations of my Boominator.
I've certainly not measured over 100db though but I don't know if I can rely on the SPL figures I'm getting with my App.
Without a more powerful Amp I would expect distortion to start at volume levels above 85%, am I right?
Am I right in thinking that with a DSP I can properly eq the system, getting rid of the very low frequencies and getting the right gains for the tops.
Plus surely having the two Maxamps will significantly improve sound quality and overall performance??
It's very hard to know what to expect, I've only ever heard one other Boominator which belongs to my mate and I helped to build.
Until now, i have not had any problems with my MAX-modules (MAX9709 / MAX9704) concerning the audio-quality, but i would recomment to change the input capacitors of the MAXAmp.
Even if ceramics arent that bad (min. X7R, high voltage rating compared to audio level), you may run into problems by their piezoceramic effects. They tend to be "microphonic".
Ceramics tend to do:
Change value my vibrations (microphonic)
Change value by voltage
Change value by temperature
Change them for i.e.
WIMA MKS4 680nF 63V
or
MKT 470nF 63V
When the MAXamp boards are build straight from the Datasheet (MAX9744), the input resistance will be 20kOhms, thus resulting in a -3dB (lower end) frequency of:
17Hz (470nF)
12Hz (680nF)
The MKS4 i use on my MAX9709 board looks like:
You may also try a 22uH inductor in series (only) with the tweeter, resulting in a lower idle power consumption and less "noise" on the upper end.
Thanks for your input
.Its now using X7R caps, but will probably upgrade this to C0G/NP0 caps in the next batch(footprint is prepared to have 10 100nF caps max). Having C0G caps in this first batch would have been simply to expensive to produce. And honestly, I couldn't hear the difference between X7R and C0G, but that could also be due to my test setup, and my not that critical ears.
Are the inductors also a improvement with non piezo tweeters? I can imagine that a ferrite bead filter + piezo tweeters will benefit from using a inductor, will definitely test this. If it improves the sound, I will add the option to my store, so that when you are going to use the MaxAmp in a Boominator with a MiniDSP, 2 inductors will be included.
Btw, I love your amps. I've seen your thread and it looks awesome with the acrylic case.
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Generally. An old ipod with a fiio e1. Or laptop and USB DAC.
I'm hoping to replace both with a FiiO X5 though as that looks like a killer product.
Ahh lads come on!
We're not all as fluent in this 'Electrospeak'!
Any chance you could translate some of this info into 'plain English' for us mere builders??
I'd love to know what you're on about and the implication of the improvements and changes your'e suggesting!
Thanks a mill!!
Thanks Saturnus...good to know that you're using a Fiio too!!
We're not all as fluent in this 'Electrospeak'!
Any chance you could translate some of this info into 'plain English' for us mere builders??
I'd love to know what you're on about and the implication of the improvements and changes your'e suggesting!
Thanks a mill!!
Thanks Saturnus...good to know that you're using a Fiio too!!
I just had another little listen with my quiet iPod touch with the Fiio connected.
I'm starting to hear what is sounding wrong.
The PHTs are not playing very clearly, there's a fuzz and a hiss to their output that's making everything sound 'dirty'.
I'm wondering are they are being stressed by playing too low but Saturnus you say my x-over network is good?
It's the same with both Amps.
I'm starting to hear what is sounding wrong.
The PHTs are not playing very clearly, there's a fuzz and a hiss to their output that's making everything sound 'dirty'.
I'm wondering are they are being stressed by playing too low but Saturnus you say my x-over network is good?
It's the same with both Amps.
The LP x-o is 2100hz and the HP x-o is 13250hz (4ohm series resistor, it's 17650hz with a 2ohm series resistor). Both slopes are very gentle and the difference between the 2 series resistors is more less or only the amount of very high frequency lift where the former has broad but less lift and the latter which has narrow but more lift. But no, the tweeter is not stressed. Not even with a 24V amp at full blast. So there has to be some unknown reason for it. The first thing I usually try is a different signal cable. No idea if that is the cause though but I'm pretty certain it's not related to the speakers or the x-o.
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I also noticed some hiss coming from the tweeter with my setup. Probably due the very high efficiency of the tweeters. Tried it with different kind of amps, different signal cables, about everything, but the "problem" remains. Only noticeable with the volume set to high volume with no signal applied though.
There's over 11khz or 2½ octaves difference between the "cut-off" points, so I don't see how you can read it as being too close. If anything too far apart would be the logical conclusion. However, due to the tweeters frequency response and baffle diffraction the chosen filter works out to be almost completely linear in both phase and impulse response with an intended lift toward 20khz to compensate for dispersion losses.
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Did you tried 22uH in Series with the PHTs? (And changed caps on the input)
Is this hiss even with unconnected source? (If yes, you may add some 10nf directly on the input to AGND)
Regards,
Christian
It can't hurt to try a 22µH in series with the PHTs. Don't think it'll make the slightest difference though as you say you experience it with both a tripath based amp (with LC output filter) and a maxim based amp (with ferrite beads).
Changing input caps should be considered very carefully though. X7R ceramics with an at least 10x higher voltage rating than the input signal peak (or in other words absolute minimum 25V and preferably 50V+ rating) are perfectly fine. For a standard Boominator with 20kohm input impedance 470nF input capacitor is optimal. Increase only with care.
Decoupling of the input is highly recommended.
Changing input caps should be considered very carefully though. X7R ceramics with an at least 10x higher voltage rating than the input signal peak (or in other words absolute minimum 25V and preferably 50V+ rating) are perfectly fine. For a standard Boominator with 20kohm input impedance 470nF input capacitor is optimal. Increase only with care.
Decoupling of the input is highly recommended.
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Yes Saturnus, as with my experience.
X7R's are fine concerning voltage rating. Increased THD will only occur at the lower frequencys. But their "might" be a microphonic problem.
Said that, i haven't noticed that this problem also occurs with a tripath (LC).
As said before, 10nF directly to AGND at the input (before decoupling cap) could help with static (idle) noise. (Helped me out at a combination of MAX9704 Class-D 2x10 in combination with a Maxim digital pot on singl supply without "live" earth connection)
Regards,
Christian
X7R's are fine concerning voltage rating. Increased THD will only occur at the lower frequencys. But their "might" be a microphonic problem.
Said that, i haven't noticed that this problem also occurs with a tripath (LC).
As said before, 10nF directly to AGND at the input (before decoupling cap) could help with static (idle) noise. (Helped me out at a combination of MAX9704 Class-D 2x10 in combination with a Maxim digital pot on singl supply without "live" earth connection)
Regards,
Christian
I appreciate the update on the speaker rec for the mini boominator.
I have a spare Helder 2020 board and I was thinking of using it for a boominator. I figured I might as well go all the way and build the big one if I am committing to the project.
So, Saturnus, Was a suitable replacement bass driver ever found for the boominator? Is there an up-to-date BOM for it?
I have a spare Helder 2020 board and I was thinking of using it for a boominator. I figured I might as well go all the way and build the big one if I am committing to the project.
So, Saturnus, Was a suitable replacement bass driver ever found for the boominator? Is there an up-to-date BOM for it?
Mornin lads.
It looks like I've found the problem that was leading to the poor sound quality.
The 3.5mm Jack socket on my front panel has an intermittent fault that was adding a load of noise to the input signal.
I feel like a bit of a dick getting ye all involved with what is actually a simple problem!
Thank you very much for your patience, I learnt a lot along the way.
I'm still only getting peaks of 96-98db before distortion but I can live with that as the sound quality is back.
Saturnus, the reason I was asking about the x-over frequency is that on my large PA the Compression drivers are rated down to 1600hz but they sound way better crossed over at 2500hz.
I was just wondering if the same logic would apply.
I've a couple of other questions though....bear with me.
The Pot that I ordered with my Maxamp operates anti clockwise, can I reverse this by switching the Red and Yellow wires?
Also, is there a unit like the Fiio that I can build in?
It'd be good not have the hassle of the extra cables and remembering to keep it charged?!
Thanks.
T
It looks like I've found the problem that was leading to the poor sound quality.
The 3.5mm Jack socket on my front panel has an intermittent fault that was adding a load of noise to the input signal.
I feel like a bit of a dick getting ye all involved with what is actually a simple problem!
Thank you very much for your patience, I learnt a lot along the way.
I'm still only getting peaks of 96-98db before distortion but I can live with that as the sound quality is back.
Saturnus, the reason I was asking about the x-over frequency is that on my large PA the Compression drivers are rated down to 1600hz but they sound way better crossed over at 2500hz.
I was just wondering if the same logic would apply.
I've a couple of other questions though....bear with me.
The Pot that I ordered with my Maxamp operates anti clockwise, can I reverse this by switching the Red and Yellow wires?
Also, is there a unit like the Fiio that I can build in?
It'd be good not have the hassle of the extra cables and remembering to keep it charged?!
Thanks.
T