Disappointed in AR48 Refoaming

[Guest RobH]

I recently had the 4” and 10” drivers in a pair of vintage AR48s refoamed professionally. I don’t know what they used for the new surrounds, but I’m sure it wasn’t the same material that AR used 30 years ago.

I didn’t expect the repaired speakers to sound exactly the same as before, but there are two differences that bother me.

1. I now hear a background hiss when the lower end of the midrange has even a little bit of energy in it. Cellos or basses seem to bring it out. The hiss stops when the music stops, so it’s not a constant noise. I’d like to know whether this is on the CD and just now audible with the speaker changes, or if it’s the speakers themselves.

2. I’ve lost a lot of the soundstage that was there before. It’s not as broad or deep. The speakers sound tighter, don’t project as much, and the imaging has gone way down.

I realize that these are not very good speakers to begin with, but need to get some more mileage out of them while shopping for replacements and would like to know if there is anything to do in the short term to make improvements.

Thanks for any comments or advice.

[Dave S.]

Hi Rob,

I don't know about the hiss, but I would double check the for correct polarity of the re-installed drivers. If something is wired out of phase that would effect the imaging. Also the new surrounds may need a little time to loosen up and break in.

[onplane]

I didn’t expect the repaired speakers to sound exactly the same as before, but there are two differences that bother me.

1. I now hear a background hiss when the lower end of the midrange has even a little bit of energy in it. Cellos or basses seem to bring it out. The hiss stops when the music stops, so it’s not a constant noise. I’d like to know whether this is on the CD and just now audible with the speaker changes, or if it’s the speakers themselves.

Rob, the only way to tell whether the noise is in the speakers or on the CD is to play similar music from other CD's and listen closely. If you only hear that objectionable noise on that one CD, chances are it's in the recording and NOT the speakers.

Regards,

Jerry

[Guest RobH]

Rob, the only way to tell whether the noise is in the speakers or on the CD is to play similar music from other CD's and listen closely. If you only hear that objectionable noise on that one CD, chances are it's in the recording and NOT the speakers.

Regards,

Jerry

Jerry,

The hiss is there on multiple CDs, but I haven't rule out the possibilty that they all are the source. I read somewhere once about hiss on older CDs, but don't recall the details.

If it's the speakers then the question is what can be done about it.

Thanks,

Rob

[Guest RobH]

Hi Rob,

I don't know about the hiss, but I would double check the for correct polarity of the re-installed drivers. If something is wired out of phase that would effect the imaging. Also the new surrounds may need a little time to loosen up and break in.

A phase check is a good idea. I haven't done one yet, because I assumed they would get it right when they did the refoam. Doesn't hurt to check.

I've got about 30 to 40 hours on the speakers, but they don't seem to have loosened up much yet.

Thanks,

Rob

[Carlspeak]

How about trying another input source. Tuner/vinyl?

[onplane]

Jerry,

The hiss is there on multiple CDs, but I haven't rule out the possibilty that they all are the source. I read somewhere once about hiss on older CDs, but don't recall the details.

If it's the speakers then the question is what can be done about it.

Thanks,

Rob

Rob, if these are older recordings you could be hearing tape hiss. Many of the vintage receivers and amps have a filter on the Tape Input to filter out tape hiss.

Try connecting your CD player to your amp via the tape in jacks.

Regards,

Jerry

[Guest RobH]

Rob, if these are older recordings you could be hearing tape hiss. Many of the vintage receivers and amps have a filter on the Tape Input to filter out tape hiss.

Try connecting your CD player to your amp via the tape in jacks.

Regards,

Jerry

I would expect tape hiss to be constantly present and particularly noticeable during quiet passages. This hiss only occurs when a narrow range of frequencies are being played. I seems to ride on top of the music, rather than being in the background. And it's not there at all when only higher frequencies are being played or there is a quiet moment.

It might actually be some form of sibilance, but I'm calling it hiss. Does that make any sense?

Thanks,

Rob

[Pete B]

I would expect tape hiss to be constantly present and particularly noticeable during quiet passages. This hiss only occurs when a narrow range of frequencies are being played. I seems to ride on top of the music, rather than being in the background. And it's not there at all when only higher frequencies are being played or there is a quiet moment.

It might actually be some form of sibilance, but I'm calling it hiss. Does that make any sense?

Thanks,

Rob

Is it a buzz by any chance? Voice coil scrape perhaps?

Lower end of the midrange will cause the most excursion for the midrange

driver and this causes the VC to move far and make the buzz noise - most

likely. It could also be the woofer since it also covers part of the midrange.

[Guest RobH]

Is it a buzz by any chance? Voice coil scrape perhaps?

Lower end of the midrange will cause the most excursion for the midrange

driver and this causes the VC to move far and make the buzz noise - most

likely. It could also be the woofer since it also covers part of the midrange.

It sounds more like a soft hiss than a buzz, but you've given me a good idea with regard to the speakers. If it's mechanical then perhaps it's only in one speaker and not both. So far I've been listening to them both together, but I'll try one at a time to see if it's isolated to just one.

Thanks,

Rob

[Pete B]

It sounds more like a soft hiss than a buzz, but you've given me a good idea with regard to the speakers. If it's mechanical then perhaps it's only in one speaker and not both. So far I've been listening to them both together, but I'll try one at a time to see if it's isolated to just one.

Thanks,

Rob

Try to determine which speaker and which driver it is, and let us know.

[kkantor]

Hi, Rob.

What kind of electronics are you using, and what's the hook up like? Is it a plain amplifier, or some kind of home theater rig?

- My first guess would be an air leak somewhere in the speaker cabinet. Are all the screws tight on the woofer? Everything sealed up properly?

- Next guess would be that there is some kind of signal processing going on... a noise reduction or sound enhancement circuit in your receiver could be the culprit.

- Finally, it could be a damaged driver, possibly some loose turns of wire on one of the voice coils. Have the speakers been played very loud for more than a brief time?

-k

I recently had the 4” and 10” drivers in a pair of vintage AR48s refoamed professionally. I don’t know what they used for the new surrounds, but I’m sure it wasn’t the same material that AR used 30 years ago.

I didn’t expect the repaired speakers to sound exactly the same as before, but there are two differences that bother me.

1. I now hear a background hiss when the lower end of the midrange has even a little bit of energy in it. Cellos or basses seem to bring it out. The hiss stops when the music stops, so it’s not a constant noise. I’d like to know whether this is on the CD and just now audible with the speaker changes, or if it’s the speakers themselves.

2. I’ve lost a lot of the soundstage that was there before. It’s not as broad or deep. The speakers sound tighter, don’t project as much, and the imaging has gone way down.

I realize that these are not very good speakers to begin with, but need to get some more mileage out of them while shopping for replacements and would like to know if there is anything to do in the short term to make improvements.

Thanks for any comments or advice.