If you get buzz only when connecting a source, it probably will be pretty easy to sort out.
Do you get buzz with no source connected?
Do you get buzz with no source and no connection from active xover to amp? (You can probably test this simply by shorting the amp input to local ground -- but make sure this doesn't force your xover to drive a dead short)
I find with these kinds of setups you often have to do some experimentation. If your boards do not have seperate power and signal grounds I'd start by bringing power ground from each amp and the xover to star ground, and DO NOT connect signal ground between xover and amps.
You should have exactly one connection to chassis ground. If you have an earth connection it should also be made at one point.
If this doesn't help, then you probably will need to draw an outline of current grounding arrangement to be able to go into more depth.
Do you get buzz with no source connected?
Do you get buzz with no source and no connection from active xover to amp? (You can probably test this simply by shorting the amp input to local ground -- but make sure this doesn't force your xover to drive a dead short)
I find with these kinds of setups you often have to do some experimentation. If your boards do not have seperate power and signal grounds I'd start by bringing power ground from each amp and the xover to star ground, and DO NOT connect signal ground between xover and amps.
You should have exactly one connection to chassis ground. If you have an earth connection it should also be made at one point.
If this doesn't help, then you probably will need to draw an outline of current grounding arrangement to be able to go into more depth.
Interesting, my hifi buzzes but only some of the time. I have narrowed this down to the preamp/active xover. Its only a preamp because of the pot! Anyway I think this has something to do with another appliance somewhere either in our house or next door polluting the mains. Sometimes it buzzes sometimes it doesnt, there is not a lot I can do about this. It may be due to less then perfect grounding in my first PCB design, but Im not sure considering its completely silent when not buzzing.
If you have only run the amps for a short period of time it could be something similar, my buzzing can last for hours at a time and then it will just dissapear. Try running the amps for an few hours or so into the speakers, just on in the background and see if it comes and goes.
My buzzing is high frequency orientated there is no lows in it whatsoever. By high freq I mean around 2000hz or something similar and its not amp oscillation.
If you have only run the amps for a short period of time it could be something similar, my buzzing can last for hours at a time and then it will just dissapear. Try running the amps for an few hours or so into the speakers, just on in the background and see if it comes and goes.
My buzzing is high frequency orientated there is no lows in it whatsoever. By high freq I mean around 2000hz or something similar and its not amp oscillation.
Really making some headway now, one cabinet around 80% done(not including finishing):
Also note the filler at the bottom of the bass cabinet, I wasn't paying attention and ended up cutting the driver recess at the wrong end! To top that its was also too big, clearly a case of cut once measure 5 times 😉 The automotive filler has done me proud though and rubbing you hand over it reveals a seamless plane, will look fine once its sprayed.
I'm biased of course but I think these look fantastic, better than I could have imagined. Really solid too, knocking on the side reveals negligible vibrations and resonances, the double layer of dedshete panels really did its job here.
Also note the filler at the bottom of the bass cabinet, I wasn't paying attention and ended up cutting the driver recess at the wrong end! To top that its was also too big, clearly a case of cut once measure 5 times 😉 The automotive filler has done me proud though and rubbing you hand over it reveals a seamless plane, will look fine once its sprayed.
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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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An externally hosted image should be here but it was not working when we last tested it.
I'm biased of course but I think these look fantastic, better than I could have imagined. Really solid too, knocking on the side reveals negligible vibrations and resonances, the double layer of dedshete panels really did its job here.
EDIT: Resized the pictures as they were distorting the page frame.
Now the electronics:
Here's the amps being tested in pairs with the superb BMM Electronics M2010R1 PSU, this is really well designed supply and I couldn't imagine it being bettered for ripple, aside from using fully regulated. 70u thick 20mm wide PCB tracks, all discrete schottky diodes for the recitifier with RF filter caps, 18 x 4400uf caps with a ten fold RC filter and bleeders for balancing and ripple rejection - nice! Highly recommended.
I'm going to try some of the suggestion from the people here, BMM and Rod Elliot to try and get rid of the hum.
Now the electronics:
Here's the amps being tested in pairs with the superb BMM Electronics M2010R1 PSU, this is really well designed supply and I couldn't imagine it being bettered for ripple, aside from using fully regulated. 70u thick 20mm wide PCB tracks, all discrete schottky diodes for the recitifier with RF filter caps, 18 x 4400uf caps with a ten fold RC filter and bleeders for balancing and ripple rejection - nice! Highly recommended.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I'm going to try some of the suggestion from the people here, BMM and Rod Elliot to try and get rid of the hum.
ShinOBIWAN said:
LOL! Now it's a lucky horse-shoe. 😉
I must say I've never made THAT mistake before, but plenty came close. Just last night I almost made a woofer cut-out that was 18cm too low, simply by adding 20cm rather than 20mm in Excel. It wasn't until I got the compasses out that I thought something looked wrong!
They are looking very nice indeed, I apologise as I haven't read the rest of your thread (will do later), your cabinets have a very 'Tony Gee' look about them (a compliment, angles and big baffles are a pig to build). It's more fun skipping to the end of a thread to see the (near) finished article, then reading how it came into being. Looking forward to updates... 😎
tiroth said:
Very interesting tiroth,
I hadn't actually thought of disconnecting the inputs - they are soldered so it was considered a hassle 😀 However when I did so the speaker are deadly quiet, I have to stick my head right up to the tweeter to hear a very faint background hiss, no hum or buzz.
What do I do to keep this great noise floor but actually have an input signal to the amps?
BTW: I don't have the active XO's in the circuit at the moment and it didn't make a difference whether it was or was not regarding the hum before. It does it with both the RME HDSP9632 soundcard and or the active XO.
Also I'd like to thank Jean Benoist from BMM electronics for creating a DC offset mod for the P101, this isn't his product and nor did he have to spend time analysing and designing this. It allow for an impressive 0.6mV measured across the speaker terminals with no input. It was around ~4-5mV before. I'm sure this has helped with the very nearly silent amps - with no input connected though 🙁
He's also suggested a change for Q7 that would help yield better performance - I will certainly check this out to.
Improved the hum issue, though not totally eliminated it to the extent of when there's no input connected.
Still can hear it from around a meter away, faintly that is. Without input its near impossible to hear without sticking your ear right upto the tweeter.
Unfortunately I had to remove the earth which is a dangerous practice and I'd rather find another solution.
Really had a good listen to the P101 and its a remarkable amp for its size and power ratings. Rod did a great job with the design.
Hmm, balanced is so much superior its not even funny.
Still can hear it from around a meter away, faintly that is. Without input its near impossible to hear without sticking your ear right upto the tweeter.
Unfortunately I had to remove the earth which is a dangerous practice and I'd rather find another solution.
Really had a good listen to the P101 and its a remarkable amp for its size and power ratings. Rod did a great job with the design.
Hmm, balanced is so much superior its not even funny.
I'm throwing around idea's for the wiring in the sub box.
Do you think parallel or serial?
Drivers specs are 2 x 8ohm 160w RMS and the amp is a single ESP project 101 rated at 150w into 8ohm and will be powering both drivers.
Parallel looks to be a 4 ohm load with 150w to each driver or serial with 8ohm load and around 75w to each.
Which would you go with?
Do you think parallel or serial?
Drivers specs are 2 x 8ohm 160w RMS and the amp is a single ESP project 101 rated at 150w into 8ohm and will be powering both drivers.
Parallel looks to be a 4 ohm load with 150w to each driver or serial with 8ohm load and around 75w to each.
Which would you go with?
ShinOBIWAN said:
definitly parallel.. voltage amp + 2 drivers in parallel = +6 db; voltage amp + 2 drivers in series = 0 db increase (..+3 db for doubling driver, -3 db for series connection = 0).
btw, its look'in reeeeel good.
Hi Sinobiwan
Nice Works.
If your body filler and Mdf are like we have hear in Oz, be careful about difeerent expansion rates for both at joins or filled screw holes etc.
We usually find the mdf shrinks compared to the filler and becomes quite visible even after spraying.....
Cheers
ps: should you consider a groove or "control joint" where the two materials are meeting in the same plane...
Nice Works.
If your body filler and Mdf are like we have hear in Oz, be careful about difeerent expansion rates for both at joins or filled screw holes etc.
We usually find the mdf shrinks compared to the filler and becomes quite visible even after spraying.....
Cheers
ps: should you consider a groove or "control joint" where the two materials are meeting in the same plane...
george a said:
Oh yes, I'm sure they are quiet the same.
I've grown acustom to MDF's penchant for joint expansion and tend to use workarounds to hide or minimise the problem. Chamfered edges is one way to get rid of the ugly expansion since the joint is on the edge of the angle.
Another is large amounts of filler on layerer or translam constructions such as the front baffle. Its looks ugly when you have bare MDF but save you a considerable headache later on.
The absolute best way to avoid all problems though is to wrap the cabinets in a cheap veneer and then spray and finish onto this.
Still not decided on a veneered finish or just a spray job.
ScottG said:
Thanks Scott,
I'll go with parallel, my only concern was if the P101 would be happy with a 4 ohm load? By all accounts the Exicon mosfets look robust and current supply isn't a problem, so I can't see why not.
Couldn't resist connecting everything up into the virtually complete cabinet and having a go.
I wish I hadn't, somewhat disappointing performance for the outlay. I'm very picky and not easily impressed but here's my gripes:
Bass is poor, ill-defined and slow. Integration between the mid and bass is terrible, these sound like some £1000 Mission's in this regard, just not upto the task of hi-fidelity reproduction.
I suspect the reason for the frankly rubbish bass performance is the poor mid-bass integration.
All I've done is a basic level match of the drivers, no phase correction, no baffle step and no EQ/notch filters.
On the plus side the midrange and treble performance is out of this world. I'd highly doubt you could significantly better it for less than silly money.
I'm loathed to throw more money on drivers but did think of the AT range of 8" drivers. I'll work hard to better what I have in front of me now and hope that the design as whole comes together.
Really I need to run some extensive SW tests and then post the results here but I'm a strapped for time at the moment. If anyone has any thoughts please chime in.
Cheers all
I wish I hadn't, somewhat disappointing performance for the outlay. I'm very picky and not easily impressed but here's my gripes:
Bass is poor, ill-defined and slow. Integration between the mid and bass is terrible, these sound like some £1000 Mission's in this regard, just not upto the task of hi-fidelity reproduction.
I suspect the reason for the frankly rubbish bass performance is the poor mid-bass integration.
All I've done is a basic level match of the drivers, no phase correction, no baffle step and no EQ/notch filters.
On the plus side the midrange and treble performance is out of this world. I'd highly doubt you could significantly better it for less than silly money.
I'm loathed to throw more money on drivers but did think of the AT range of 8" drivers. I'll work hard to better what I have in front of me now and hope that the design as whole comes together.
Really I need to run some extensive SW tests and then post the results here but I'm a strapped for time at the moment. If anyone has any thoughts please chime in.
Cheers all
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ShinOBIWAN said:
LOL
I actually meant £100 and not £1000!
Also crossover points are 3.1Khz & 350hz.
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Joined 2002
jleaman said:
Thanks, your own speakers look great too. Love curved cabinets!
I'm kinda hesitant to post this here as I'll probably get laughed off the board 😱 but the reason for the poor bass integration could have been the fact that when I did the wiring on the bass drivers, I'd inadvertantly wired them both out of phase with regards to the mid and treble. 🙄 😉
Sounds much, nay, infinitely better. Now very tight, well defined and the mid/bass integration is seemless.
I now ask myself, if I can't do a simple job such as wiring the drivers in phase, how on earth did the electronics I built work first time?!? Doesn't exactly instill confidence 😀
Much reviewing and tweaking ahead methinks. I'm a little too excited to post subjectively about the sound at the moment, so I'll restrain myself and say they sound good for now.
A quick run through with true RTA should show up some of the problems.
Also you won't get the best until you have the pair running.
Also you won't get the best until you have the pair running.
m0cea said:
No mic at the moment, so RTA is out. Though this won't do and I'll be sorting one very shortly.
All I've gone on so far is an SW Walin jig 2, measuring driver parameters and such.
I also agree that one speaker doesn't cut it for serious testing but it does give me an idea of the tonal quality.
That's funny - I did a similar thing. Wired one of my mids out of phase the first time, and things just didn't gel. Now I battery test all my woofers & mids after they're mounted.
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