Hi All
So i own a lovely pair of quad 57s which i've owned for almost 2 years. I bought them second hand where they had been worked on, new treble protection boards, EHT boards done etc basically everything was updated except the panels which were tested to be ok.
I recently moved home and these were in storage for around 3 months, i recently got them back into the house and left them connected for 24 hours, i started to notice one speaker felt louder than the other.
I swapped the speakers over (left to right, right to left) changed amplifiers and it was still the same. So i thought ok, maybe being in storage, temp changes ill leave them to charge for a few days.
Today i took some measurements of each speaker. Left bass panel, treble panel and right bass panel. Speaker A is the good speaker, speaker B is the one i have issues with.
First thing was a pink noise test, i setup my umik mic around 5 cm away from each panel and measured the dB.
On Speaker B the treble panel was some 2.4db lower than the bass panels, where as speaker A all the panels were similar.
Speaker B was measured at 80dB white noise
With the same output volume i measured speaker A which ended up being 82db!
Speaker A
Bass panels 82db, treble panel 82dB
Speaker B
Bass panels 80db, Treble panel 77.6db
Here the weird part, i did some frequency sweeps keeping the speakers at the same volume and the panels measure similar?
Treble panels speaker A&B
Left Bass Panels
Right Bass Panels
Now they seem to both perform well so all the panels are working, ok speaker B treble panel seems to have lost 3dB of volume and i may need to look at the panel. Overall there just seems to be a loss of efficiency and volume on speaker B?
Just need advice on what to do now and what to test?
Any advice appreciated!
Many thanks
So i own a lovely pair of quad 57s which i've owned for almost 2 years. I bought them second hand where they had been worked on, new treble protection boards, EHT boards done etc basically everything was updated except the panels which were tested to be ok.
I recently moved home and these were in storage for around 3 months, i recently got them back into the house and left them connected for 24 hours, i started to notice one speaker felt louder than the other.
I swapped the speakers over (left to right, right to left) changed amplifiers and it was still the same. So i thought ok, maybe being in storage, temp changes ill leave them to charge for a few days.
Today i took some measurements of each speaker. Left bass panel, treble panel and right bass panel. Speaker A is the good speaker, speaker B is the one i have issues with.
First thing was a pink noise test, i setup my umik mic around 5 cm away from each panel and measured the dB.
On Speaker B the treble panel was some 2.4db lower than the bass panels, where as speaker A all the panels were similar.
Speaker B was measured at 80dB white noise
With the same output volume i measured speaker A which ended up being 82db!
Speaker A
Bass panels 82db, treble panel 82dB
Speaker B
Bass panels 80db, Treble panel 77.6db
Here the weird part, i did some frequency sweeps keeping the speakers at the same volume and the panels measure similar?
Treble panels speaker A&B
Left Bass Panels
Right Bass Panels
Now they seem to both perform well so all the panels are working, ok speaker B treble panel seems to have lost 3dB of volume and i may need to look at the panel. Overall there just seems to be a loss of efficiency and volume on speaker B?
Just need advice on what to do now and what to test?
Any advice appreciated!
Many thanks
Attachments
Maybe the corner placement affects the bass, try measuring both in the same position?
EDIT: Is that 50dB per/div in the graphs!? Then forget my comment..
EDIT: Is that 50dB per/div in the graphs!? Then forget my comment..
No I tested it both sides and it's the same, definite loss of power/volume from the speaker regardless of placement.
Might be time for the panels to be replaced, repaired of upgraded.
For 40 year old or more panels, they look nice. But they are pretty old.
Before you get crazy on panel rebuilding or replacement, try swapping your power supplies from one speaker tot he other and see if the problem follows the supply.
Sheldon
Any reason why? Will it help determine the problem?
Thanks Sheldon I'll give it a go.
Ok so I swapped over the power supplies and it made no difference, the tweeter panel still measuring lower and speaker sounds lower.
So I guess that means my tweeter panel even though it looks in great condition needs to be done? I assume that this also affects the bass panels when there's a tweeter panel issue?
I guess it's best to do both tweeter panels to match them.
Makes me wonder of I should just do all the panels? Then again cost is a factor.
How much would it cost to do just the tweeter panels, later date I can decide whether to update the bass panels.
Thanks
So I guess that means my tweeter panel even though it looks in great condition needs to be done? I assume that this also affects the bass panels when there's a tweeter panel issue?
I guess it's best to do both tweeter panels to match them.
Makes me wonder of I should just do all the panels? Then again cost is a factor.
How much would it cost to do just the tweeter panels, later date I can decide whether to update the bass panels.
Thanks
Attachments
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Did you give the speakers a day or so to charge up? They can be quite slow.
Stretching the scale on the plots above would help us see details that are obscured by the 10,000 foot view.
Sheldon
Stretching the scale on the plots above would help us see details that are obscured by the 10,000 foot view.
Sheldon
I gave them an hour. Ok I'll retest tomorrow and stretch the scales. But it feels like the treble panel needs attention.
It indeed might need attention, but when the panels get old, they rarely charge at the same rate. I just checked out a set of quads from a local guy who had just started using them again and he was concerned that they were unbalanced. I measured them after about 12 hours of charging and they were indeed unbalanced (about 6 dB different). I didn't dig into them that day because I'm a lazy bastard. I came down the next day and took the back off the low output one and the power supply measured just fine. So I decided to test them again and they were within 1dB of each other. But it took more than a day to get there.
Sheldon
Retested after a good 24 hours. Although it sounds a little better, one speaker is still dominant, and the treble is still around 2-3db down.
I guess it's time to get the panels refurbished?
I'm thinking to get the best out of these I may aswell do all the panels and have them refreshed.
I guess it's time to get the panels refurbished?
I'm thinking to get the best out of these I may aswell do all the panels and have them refreshed.
Looking at the first post, the scales are so bad that it is hardly possible to get a good idea of any differences.
What can be seen is that both speakers are very close, show the same overall behaviour, and that the small differences can be accounted for by room effects. Especially with the physically different positions shown - it's a miracle they are not much more different!
Those room effects can also account for perception differences. Of course those perception differences can also be accounted for by looking at the graphs and concluding one must be louder.
In other words, this thread has all the hallmarks of chasing ghosts. 😎
Jan
What can be seen is that both speakers are very close, show the same overall behaviour, and that the small differences can be accounted for by room effects. Especially with the physically different positions shown - it's a miracle they are not much more different!
Those room effects can also account for perception differences. Of course those perception differences can also be accounted for by looking at the graphs and concluding one must be louder.
In other words, this thread has all the hallmarks of chasing ghosts. 😎
Jan
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I think people are looking too much into the graphs.
The graphs just show that the speakers perform similar at the same volume.
What I was showing is that the panels aren't completely ruined and they work.
As stated one speaker is lower than the other, nothing to do with room acoustics or measurements.
Yes I have moved the speakers and it's the same, yes I have tried pink noise, sine waves, tones and it's still the same.
So not chasing ghosts, just trying to find out if my treble panels need to be refurbished and the process of finding this out.
If I was doing serious measurements then yes I'd take care, but these speakers (the panels them selves) are almost 35-40 years old so sooner or later they will need some work.
Also 2-3db is a very noticeable with these speakers.
The graphs just show that the speakers perform similar at the same volume.
What I was showing is that the panels aren't completely ruined and they work.
As stated one speaker is lower than the other, nothing to do with room acoustics or measurements.
Yes I have moved the speakers and it's the same, yes I have tried pink noise, sine waves, tones and it's still the same.
So not chasing ghosts, just trying to find out if my treble panels need to be refurbished and the process of finding this out.
If I was doing serious measurements then yes I'd take care, but these speakers (the panels them selves) are almost 35-40 years old so sooner or later they will need some work.
Also 2-3db is a very noticeable with these speakers.
With all due respect, how do you know they are different, with the measurements showing that, especially in the treble, they are pretty much carbon copies?
Jan
Yes that's my point they are almost carbon copies which is great.
As mentioned earlier i set the level of the speakers so they were the same, it meant the bad speaker had to be a little louder to match the good speaker.
Again I was just seeing my panels weren't damaged (im sure if they were it wouldnt be similar to the other speaker)
I didn't put all the measurements up just a snap shot (I admit I did it quickly just get some readings up).
As I said again you can hear they are different and playing pink noise and tones while measuring dB of the panels shows this.
Guess you have to be here to see and hear it, there is a noticeable difference.
And i rotate speakers and systems in my listening space so I have an idea of what doesn't sound right.
So it's either the Panels, output transformer or tweeter protection board, which are all just 2 years old (all the parts and components were changed to newer updated parts).
But it all seems to be pointing to a bad treble panel
But it all seems to be pointing to a bad treble panel
Check the resistors in the output transformer, bypass the treble protection and see if either makes a difference.
Have you a HV probe - you could check the HV on that treble panel and compare to the other one?
Have you a HV probe - you could check the HV on that treble panel and compare to the other one?
I've decided to get these refurbished by a professional.
I would like them at their best so decided to just get them overhauled and serviced.
I'd like all the panels done, transformers checked etc and just not worry about failing parts.
Thanks for all those that helped.
I would like them at their best so decided to just get them overhauled and serviced.
I'd like all the panels done, transformers checked etc and just not worry about failing parts.
Thanks for all those that helped.