Deaf Cat,
where are you based?
There are bound to be a few Members with the simple gear needed to check the frequency response of your amplifier for you.
A scope and oscillator is all that is needed.
Just sweep across the frequency range and see that the "height" of the scope trace does not change significantly in the audio passband.
A -1dB loss anywhere in that range will be seen as a drop of ~12% of the "height".
12% drop is very easily seen on the scope trace.
You can also easily see a variation of 0.5dB on a scope that is displaying ~6 divisions of peak to peak.
where are you based?
There are bound to be a few Members with the simple gear needed to check the frequency response of your amplifier for you.
A scope and oscillator is all that is needed.
Just sweep across the frequency range and see that the "height" of the scope trace does not change significantly in the audio passband.
A -1dB loss anywhere in that range will be seen as a drop of ~12% of the "height".
12% drop is very easily seen on the scope trace.
You can also easily see a variation of 0.5dB on a scope that is displaying ~6 divisions of peak to peak.
Your guess is wrong. Most pieces of equipment cannot be altered internally to increase or reduce mid frequencies, except by adding tone controls. When frequency response problems occur accidentally they will always be at frequency extremes, not mids. The most you could do is reduce lows and highs, and then mids will appear to be boosted. Changing PSU caps will definitely not affect mids.Deaf Cat said:
If two amps sound significantly different in the same setup then at least one of them has a problem. The problem may be accidental or deliberate, but before you can fix it you need to know which amp it is. That means measurements. Then, armed with measurements, you can determine what sort of fault can cause the observed problem and look for it.
It could simply be that one amp has been mis-engineered to have a boosted mid-range and the other sounds low as a comparison. If so, tone controla are the answer.
I am in Chingford, London, I have been looking out for a second hand scope but do not know how to use it (cold never get the hang of them at college) and prices vary considerably, it would probably sit in the cupboard most of its life anyway, so to have someone check it for me would be rather wonderful.
I was hoping not to have any more components in the chain, hence the resistance for an equalizer, but that would probably be preferable than looking for a whole new amp, seeing as I'v had this one so long and I've not heard anything that has made me want to change in the last 10-15 years..
Another 'mad' thought, along the lines of tone control 😉 sorry..
I dont suppose I could add another active crossover board, to my active XO box (there is room, psu is big enough) so the signal splits, say, ( I know I would need measurements for this figure ) between 2.3kHz and 4kHz, then 4 and above, for the Maia, I can then attenuate or boost top or bottom half of the Maia's signal and, rejoin the signal before the amp..
Does anybody say Yes 🙂
I was hoping not to have any more components in the chain, hence the resistance for an equalizer, but that would probably be preferable than looking for a whole new amp, seeing as I'v had this one so long and I've not heard anything that has made me want to change in the last 10-15 years..
Another 'mad' thought, along the lines of tone control 😉 sorry..
I dont suppose I could add another active crossover board, to my active XO box (there is room, psu is big enough) so the signal splits, say, ( I know I would need measurements for this figure ) between 2.3kHz and 4kHz, then 4 and above, for the Maia, I can then attenuate or boost top or bottom half of the Maia's signal and, rejoin the signal before the amp..
Does anybody say Yes 🙂
One of the easiest ways to check that questionable mid range is to connect the amp up to a full range source (CD player, tuner, etc) and plug in a pair of high impedance headphones to the amp's output and have a good listen - any obviously missing mids will show up straight away and this will confirm that the amp in question does indeed have a problem with freq response
Personally, I've never had a problem with a lack of mids in any amp over the years but have had numerous problems with incorrect source impedances, loads, feedback, etc and the biggest bogieman of all, electronic crossovers.
Now, there's no great difficulty in producing whatever shaped freq response from an amplifier that you may desire but it does require a fairly good grasp of the circuit and it's behaviour - not so easy to do by 'guesswork' alone
Anyway, hopefully you can sort out what exactly is the problem with the lacking mids and then possibly a simple solution can be found
Personally, I've never had a problem with a lack of mids in any amp over the years but have had numerous problems with incorrect source impedances, loads, feedback, etc and the biggest bogieman of all, electronic crossovers.
Now, there's no great difficulty in producing whatever shaped freq response from an amplifier that you may desire but it does require a fairly good grasp of the circuit and it's behaviour - not so easy to do by 'guesswork' alone
Anyway, hopefully you can sort out what exactly is the problem with the lacking mids and then possibly a simple solution can be found
On your post #18, you said you have 2 of the Marchand XM44EMB crossovers set at 2.3kHz with the Regs as the high pass amp and the Exon for the low pass
Why do you need 2 of the XM44 stereo Xovers, particularly with just the 2 way filters set at 2.3kHz?
Can you add a link to some info about these Ditton AV3 speakers (nothing under that description on Google) - did you disconnect the internal passive Xovers, if it has them?
Why do you need 2 of the XM44 stereo Xovers, particularly with just the 2 way filters set at 2.3kHz?
Can you add a link to some info about these Ditton AV3 speakers (nothing under that description on Google) - did you disconnect the internal passive Xovers, if it has them?
How do you set up the correct levels ? There is no reason to suspect your 2 substituted amplifiers have the same voltage gain and even quite a small difference in volume makes a very big perceived difference in 'sound'. One CRITICAL aspect of comparison is in ensuring that you are comparing like with like.
There are multiple places this can go wrong :-
(1) active crossover outputs, not just low / high pass but left / right as well.
(2) gain of the power amplifiers (probably fixed)
(3) sensitivity of the drive units / speaker enclosures
dc
PS: another possible way to screw things up is by getting a phase difference 🙂
There are multiple places this can go wrong :-
(1) active crossover outputs, not just low / high pass but left / right as well.
(2) gain of the power amplifiers (probably fixed)
(3) sensitivity of the drive units / speaker enclosures
dc
PS: another possible way to screw things up is by getting a phase difference 🙂
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Ah ha, the first part of your comment is what I thought was possible, and what I was hoping for 🙂
The second part makes it somewhat impossible as I have no clue about ccts, and no one else who knows what they are doing can see the cct board, or schematic! :-(
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One XM44EMB board allows for two filter cards to be fitted, one low one high, so one board for the left speaker and one board for the right, I have not got the XM44, I have the XM44EMB's
No info on net about the AV3's anywhere.. I have looked a number of times.
yes the internal passive crossovers are in the loft, the speakers are in the lounge ;-)
It was easy to hear the difference, from the Maia that I have listened to for years, different volumes different tracks, the first track I listened to with the 60p I noticed the difference, and every track since at what ever volume. Yes I have tweeked the Exons up on the XO, to balance the sound out, as the 60P has far more oomph than the Maia.. The mid range void is filled with the 60P, but I by far prefer the foot tapping, sound of the Maia - just would be nice if it could have some more mid range.
No info on net about the AV3's anywhere.. I have looked a number of times.
yes the internal passive crossovers are in the loft, the speakers are in the lounge ;-)
It was easy to hear the difference, from the Maia that I have listened to for years, different volumes different tracks, the first track I listened to with the 60p I noticed the difference, and every track since at what ever volume. Yes I have tweeked the Exons up on the XO, to balance the sound out, as the 60P has far more oomph than the Maia.. The mid range void is filled with the 60P, but I by far prefer the foot tapping, sound of the Maia - just would be nice if it could have some more mid range.
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Did the amp "sound right" when these speakers were still passive cross-overed?
Your recent posts point to a crossover error and not missing Mids in the power amp.
I think your first post misguided us all about your apparent problem.
I now withdraw the need to get your amplifier frequency response checked.
You have created the error elsewhere.
Your recent posts point to a crossover error and not missing Mids in the power amp.
I think your first post misguided us all about your apparent problem.
I now withdraw the need to get your amplifier frequency response checked.
You have created the error elsewhere.
You need to measure with measuring equipment, ears / brains have a strong tendency to deceive. There may well be something amiss with your setup but its certainly not due to what you think is wrong ...
I went for the active crossover as an experiment, and the difference was more control, clarity & punch across the board, a very pleasing result.
I do not remember a sudden loss of mid range when I switched over, just the increased, control clarity and punch.
Checking back though, it does seem that not long after going active I was thinking of going 3 way active to enable the mids to be tweeked up..
I did at one point connect up my system (while stressed tired etc) with no active XO the speakers sounded dreadful but there was a nice lot of mid range. Could it be possible that the original passive XO's were a little knackered/cheap/slack and allowed a bit too much of a crossover from both tweeter and woofers resulting in more mid range, and that switching to a decent crossover everything cleaned up and with a tight crossover rather than a slack crossover the mids have vanished..?? - or now correct - in some way.
I do not remember a sudden loss of mid range when I switched over, just the increased, control clarity and punch.
Checking back though, it does seem that not long after going active I was thinking of going 3 way active to enable the mids to be tweeked up..
I did at one point connect up my system (while stressed tired etc) with no active XO the speakers sounded dreadful but there was a nice lot of mid range. Could it be possible that the original passive XO's were a little knackered/cheap/slack and allowed a bit too much of a crossover from both tweeter and woofers resulting in more mid range, and that switching to a decent crossover everything cleaned up and with a tight crossover rather than a slack crossover the mids have vanished..?? - or now correct - in some way.
Did you check the phase? Maybe the Maia inverts the polarity and your previous amp didn't or vice versa. Try swapping the polarity of the speakers and see if that helps.
Or maybe the Maia simply has different gain to the amp it replaced, and that upsets your active crossover setup.
This thread is a fantastic example of the kinds of babies that get thrown out with the "All power amps sound the same" bathwater. Sure they all sound the same, in a careful lab test where every other variable is controlled.
Or maybe the Maia simply has different gain to the amp it replaced, and that upsets your active crossover setup.
This thread is a fantastic example of the kinds of babies that get thrown out with the "All power amps sound the same" bathwater. Sure they all sound the same, in a careful lab test where every other variable is controlled.
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hmm interesting i am now thinking it would be good to measure (me thinking measure!) my speakers as passive and then as active to see if there is a dip in the frequencies anywhere.
Many thanks to all in this thread, I never worried about measurement before, a little bit of trial and error and all is well, but as things get complicated I can now see that measurement would help track down where & when things may have gone amiss, thank you for helping me understand measurement is key!
I do have a mic and will check out the software mentioned earlier.
Also makes me think I should get hold of some decent speakers, just to see if they act the same with my set up...
Maybe the 60P is mid and top end happy, as in the spare bed room I dug out an old power cable that smooths top end, a lot, to make the 60p listenable with some cdm 1nt's.
Oh boy! I can see now it could be any number of things, 😱
Many thanks to all in this thread, I never worried about measurement before, a little bit of trial and error and all is well, but as things get complicated I can now see that measurement would help track down where & when things may have gone amiss, thank you for helping me understand measurement is key!
I do have a mic and will check out the software mentioned earlier.
Also makes me think I should get hold of some decent speakers, just to see if they act the same with my set up...
Maybe the 60P is mid and top end happy, as in the spare bed room I dug out an old power cable that smooths top end, a lot, to make the 60p listenable with some cdm 1nt's.
Oh boy! I can see now it could be any number of things, 😱
Only tried with the Maia, soundstage depth vanished or re-appeared with a swap.
Variables a! I find it confusing that changing one component into another system, does not always have the exact same effect in a different system..😕
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With no XO in a 2 way speaker set up (that was designed to have a XO), wont you have the tweeter and woofers producing some of the same frequencies, therefore where they overlap, producing the same frequencies, would those frequencies not be louder than the ones that are not overlapped? and they would be mid range..?
Ah, as I have changed and tinkered with my speakers, re-enforcing, bracing drivers/box, stuffing, etc, by trial and error listening tests, maybe that has aided the void in midrange when I upgraded the XO to a decent quality one.. and thus they are not anything like they were designed, Oops, they do sound much better though, just need some mid range :-o
I should have measured before and after each mod to give me a base line for reference!
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