If you're thinking ANY of those underlined make the slightest difference to the sound, you shouldn't be here 😀
If you want to make tonal changes you don't redesign the amp (which is supposed to be flat and high quality), you simply adjust your tone controls - if you don't have any, then add some - personally I would suggest a graphic equaliser would probably be best for you?.
:-D
ha ha I was trying to keep my set up, signal path, simple :-0 that has not worked..
and your suggesting adding even another box 🙂 Oh dear, can't I just change a capacitor ;-)
If you could see inside my amp, you would understand I'm not sticking to the original designer and his layout or choice of components (only slight alterations).
Yes I love the sound of it that is why I have it, and yes, my repair guy thinks I have butchered it, but I like it.
After my last attempt at soldering he repaired it and he changed some internal cables and asked me to have a listen, after his repair and simple mod, sounded smoother 🙂
ha ha I was trying to keep my set up, signal path, simple :-0 that has not worked..
and your suggesting adding even another box 🙂 Oh dear, can't I just change a capacitor ;-)
If you could see inside my amp, you would understand I'm not sticking to the original designer and his layout or choice of components (only slight alterations).
Yes I love the sound of it that is why I have it, and yes, my repair guy thinks I have butchered it, but I like it.
After my last attempt at soldering he repaired it and he changed some internal cables and asked me to have a listen, after his repair and simple mod, sounded smoother 🙂
Lack of midrange clarity can be a power supply issue. At the least bypass the supply rails with a 1 uF film capacitor on the PC Card. A power line filter may prove useful.
It is very unlikely there is a frequency response issue.
Even though power line frequencies are low they are where the ear is not very sensitive. However most power lines have harmonics well into the midrange.
The simplest test is to flip one AC plug in your system, if possible, to see if there is a difference. As there should not be one if you hear a change it indicates a deficiency in the power supply.
It is very unlikely there is a frequency response issue.
Even though power line frequencies are low they are where the ear is not very sensitive. However most power lines have harmonics well into the midrange.
The simplest test is to flip one AC plug in your system, if possible, to see if there is a difference. As there should not be one if you hear a change it indicates a deficiency in the power supply.
Wow I had not even thought of looking at other psu units in the chain, the linear supply for the squeezebox must be 8 years old and been on pretty much 24hrs a day for maybe 5 of those years...
The pc power supply, well that is a SMPS, on an old Pentium D pc(used to live in an office) that may well have aged too..
Thanks for the tip!
The pc power supply, well that is a SMPS, on an old Pentium D pc(used to live in an office) that may well have aged too..
Thanks for the tip!
If it is of any age the electrolytic's will be degrading.
I would replace them and see if that improves matters.
I would replace them and see if that improves matters.
In the maia there are 3x 4700uF per rail most of these are around 4700 but two are closer to 4600 i am guessing that is not far off Can caps degrade performance wise but still show their original capacitance?
The MASSIVELY most common failure of electrolytic's is high ESR - however, this doesn't really apply to the 4700uF's in your case, it's mostly a problem for switch-mode usage.
In the case of high ESR it's normal for the capacitance to be fairly normal, and usually within tolerance.
However, there seems little reason to even suspect a fault in the amplifier?.
I think there is ample reason to suspect an amplifier fault. The OP said (post 22):Nigel Goodwin said:
Unless, of course, he is talking about a different amp.Deaf Cat said:
Remotely diagnosing an alleged fault in an amplifier which has apparently been 'got at' by someone who admits to little knowledge and limited experience is usually rather difficult, especially when there are no measurements (and probably no possibility of measurements) to confirm the fault. All we actually have is "I swapped the amps; they sounded different". All that tells us is that at least one of them is not working properly in some unspecified way. It may simply be that one was deliberately (or accidentally) engineered to have a non-flat frequency response.
Ah interesting about esr, thankyou i will see if i can have a measure.
I agree i dont think there is a real fault with the amp just for fun thought of experimenting...
See if it can get closer to what my ears are wanting.
Edit
I dont think i have tinkered enough yet to alter the original flat (or otherwise) response.
Sorry yes everything is vauge as i am just starting to learn a little about electronics.and yes i am finding it real tricky deep.stuff so just scratching the surface finding it interesting and yes i can see a little knowlede could cause problems that i would have to be paying someone to fix so amy trying to hold back the temptation to play too much!
🙂
I agree i dont think there is a real fault with the amp just for fun thought of experimenting...
See if it can get closer to what my ears are wanting.
Edit
I dont think i have tinkered enough yet to alter the original flat (or otherwise) response.
Sorry yes everything is vauge as i am just starting to learn a little about electronics.and yes i am finding it real tricky deep.stuff so just scratching the surface finding it interesting and yes i can see a little knowlede could cause problems that i would have to be paying someone to fix so amy trying to hold back the temptation to play too much!
🙂
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Could this be caused by a difference in output impedance of the two amplifiers and a tricky load caused by the crossover?
No sure how to fix it though...
Brian
No sure how to fix it though...
Brian
Yes the capacitors age and as they do they provide a bit less filtering particularly at higher frequencies. Again the simple test is to add in some film capacitors. I have used as much as 300uF but you can start with 1uF but 10uf would be better.
It's not impossible, especially as there are 2 woofers - if they're in parallel and the Q of the Xover at the woofers' top end isn't optimum. Not that likely though.
I've just thought of another possibility, there's always been rumours of hi end amp manufacturers tweaking the frequency response a little to give their amp the edge in shop demos. I can easily hear 0.5dB shelf lift or cut above 1kHz but the spec is still within the usual quoted +-1dB or +-3dB wideband figures.
Ah I guess you can't measure the ESR of a cap with a multimeter, I guess the meter pumps out a voltage to calc the resistance and the cap just eats it up..
My LCR meter (PEAK atlas LCR40) sometimes gives the resistance but not always, it has not done it with any of the original Maia caps??
The crossover boards have a pot, that permits a, maybe 12dB, adjustment to each filter so the >2.3Khz can be turned up or down but the bit just above the 2.3 seems to be avoided by the Maia, and the 60P fills it...
I have some new caps for the psu that is why it is in bits, so will see how that goes.
There are two Rifa PHE 426's I think one on each input, (the only other bit of the board that I have a rough idea what it does!) I guess these would be okay with age? as no one has mentioned them.
I don't seem to remember the Maia being short on mids when it was young/new but then my ears were not so fussy then, maybe only in the last few years...
My LCR meter (PEAK atlas LCR40) sometimes gives the resistance but not always, it has not done it with any of the original Maia caps??
The crossover boards have a pot, that permits a, maybe 12dB, adjustment to each filter so the >2.3Khz can be turned up or down but the bit just above the 2.3 seems to be avoided by the Maia, and the 60P fills it...
I have some new caps for the psu that is why it is in bits, so will see how that goes.
There are two Rifa PHE 426's I think one on each input, (the only other bit of the board that I have a rough idea what it does!) I guess these would be okay with age? as no one has mentioned them.
I don't seem to remember the Maia being short on mids when it was young/new but then my ears were not so fussy then, maybe only in the last few years...
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I would also add my vote to the earlier advice that you perform the measurement, at least two frequency response at speakers output, measured with white noise or sweep. You may also decide to measure the frequency response at loudspeakers. This is the only way to find out if you have a midrange dip.
I'm a bit surprised that you haven't tested the filter settings/performance of the XM44EMB crossovers and why do you need 2 of them for a 2 way Xover at 2300HZ? in your system - each one accepts 2 channel inputs (L & R, either balanced or unbalanced) so why have you configured your system with 2 separate Xover units?
Despite what they tell you, these Sallen Key filter systems are not all that simple and with the wide variety of options available, mistakes are very easy to make with filter slopes, filter frequencies, etc.
I would start here rather than just concentrate on a possible problem with the mid response in the amp
Despite what they tell you, these Sallen Key filter systems are not all that simple and with the wide variety of options available, mistakes are very easy to make with filter slopes, filter frequencies, etc.
I would start here rather than just concentrate on a possible problem with the mid response in the amp
We've known since #18 that the OP says he is comparing 2 amplifiers in the same system. I don't see how the periferal issues of other individual "boxes" in the system come into this, assuming the amps both have similar input impedance, no preamps or filter circuits to fiddle with and they have similar speaker connections.
It seems to be quite a "messed about with" and jumbled system but it should not otherwise be different for comparison purposes.
It seems to be quite a "messed about with" and jumbled system but it should not otherwise be different for comparison purposes.
As the 'peripheral issues of other boxes' are the main parts of the 'bodge up' that will affect the frequency response, it sounds more likely than anything else 😀
As far as the power amp goes, he's never provided a circuit, he admits it's been bodged about and changed (in ways no one knows), and has never even done the basic obvious tests.
Basic obvious tests - disconnect everything - connect a full range speaker to the output of the amp, fed the amp from a known good source (such as a CD player). See how it sounds then.
If required, do the same test with the other amplifier, and compare how they sound (making sure volume is identical).
I agree from a theory measurement point of view, I should do a lot more tests, but I'm not trying to please measurements or get an exact flat response.
I'm trying to please my ears through which I enjoy music, if my ears want more mid freqs that is what I should do, don't you think? Or am I missing the point?
I would guess..? (as I know not how or if) any piece of equipment in the chain could be altered internally to increase lower/mid/top freqs, and the power amp that is in bits (only had its binding posts changed at the moment) could be altered in some way.
My system my ears the Maia seems to be missing mids compared to the 60P, in a mates system the Maia also seems to miss mids, to which my mate was first to comment on not knowing my thoughts. So my ears my mates ears, my system my mates system all show the Maia is missing mids..
Is there any way to increase the possibility of more mids apart from checking/testing/trialling out the psu caps?
(which is work in progress at the moment)
Cheers
🙂
I'm trying to please my ears through which I enjoy music, if my ears want more mid freqs that is what I should do, don't you think? Or am I missing the point?
I would guess..? (as I know not how or if) any piece of equipment in the chain could be altered internally to increase lower/mid/top freqs, and the power amp that is in bits (only had its binding posts changed at the moment) could be altered in some way.
My system my ears the Maia seems to be missing mids compared to the 60P, in a mates system the Maia also seems to miss mids, to which my mate was first to comment on not knowing my thoughts. So my ears my mates ears, my system my mates system all show the Maia is missing mids..
Is there any way to increase the possibility of more mids apart from checking/testing/trialling out the psu caps?
(which is work in progress at the moment)
Cheers
🙂
I don't think that has the slightest hope of producing more mid, it's not a fault which ever happens (or potentially even 'could' happen).
As I've outlined, you first need to identify if there's actually a 'fault', which is MOST unlikely - in the unlikely event that the amp IS lacking in mid, you probably only need to reverse whatever changes were made to the amp (which presumably would have been specifically done to reduce the mid?).
And as I've also suggested, add a graphic equaliser so you can make it perform how YOU want it, as opposed to how it's supposed to sound.
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