Time for reconing?

[garyb]

Hi, long time lurker first time posting. I have a set of Valencias(464b) with the 416-8z LF drivers.
The lowest bass frequencies are a bit woolie or loose. Both the preamp and amp have stiff
power supplies and the bass is tight with other speakers. Could this possibly be time for a reconing?
If so I'll probably send both LF and HF drivers in for rebuilding.
Thanks
Gary

[bowtie427ss]

Just my novice opinion here, maybe a recharging of the magnets is in order.

If you're running moderate solid state power, and your listening habits show the 416's large dynamic peaks, remagging may be a moot point as large power spikes have a tendancy to weaken alnico magnets.

FWIW, your description is pretty much how proper working 416's in a BR enclosure sound to me, a little flabby on the bottom.

There may be some "tricks" involving re-tuning the cabinets that might tighten up the bottom, there are some board members here that can spell out all the possibilites for you (pinging GM, bfish, etc.)

If it were me, and i were considering throwing money at them, i'd opt for a new pair of GPA 416's with ferrite motors.

The consensus among those who have tried the new GPA 416's is that they're by a margin the best to date.

This of course is all entirely my opinion, available locally with coffee and donuts.

[garyb]

Thanks, I've owned them for over a year and always run them with tube gear at low levels. What are the signs of a weakened suspension?
Gary

[bfish]

I suppose it's possible, but there'd likely be sizable puddles at the bottom as a result.

I've never messed with the original Altec dopes, but one of the desired properties is that it be unaffected by temperature. Otherwise, the compliance would vary with temp changes. In experimenting with the current dope, I tried to lessen the viscosity by heating the container to 135 degrees in hot water...didn't help a bit.

[LICORNE]

After all these years theres natural fatigue that sets in.

I would look at replacing the crossovers with new
ones.

The spider might not be straigt (sagging).

GPA could tell you right away just by looking.

This is my .02 cents worth.

[bfish]

Convergence, what feature of an aging XO would cause the "wooly, loose" bass the OP inquired about?

FWIW, a friend recently disemboweled an old N800F and tested each component. Everything was within 5% of rated value. Says quite a bit for those old ELPAC caps after 30+ years in Arizona heat.

[LICORNE]

As for the XO I was thinking of the system as a whole.

The N series was pretty good design nice big boxes and I'm not surprised that their values did not shift that much. But does the Valencia have one of those little green box Hey see what I mean.

...............

[bfish]

Originally posted by Gary Buck:
...What are the signs of a weakened suspension?

<font size="2" face="Verdana, Helvetica, sans-serif">Normally, a coil rub. You can check for that with no signal by lightly moving the cone with your fingers.

Are the cabs structurally solid? Rapping them all around with your knuckles might reveal something loose and buzzing. Air leaks other than the port can cause problems too.

The N800F XO can be driven from either 8 or 16 ohms. If you have both taps on your amp, you might try switching over, as the amp's internal impedance affects the LF response/damping.

[bowtie427ss]

Air leaks other than the port can cause problems too.

<font size="2" face="Verdana, Helvetica, sans-serif">Good point!

Given the OP's geographic location, and it's inherently hot climate, could enough dope run off the suspension to be letting it pass air?

<font color="#FFFFFF" size="1">[ December 06, 2007 12:54 PM: Message edited by: bowtie427ss ]</font>

[garyb]

Some good points, I like the Altecs enough to spring for a rebuild of all drivers. I recapped the crossovers which sweetened the horns a bit.
The problem is a narrow range of lower frequencies that slightly overshadow the midrange. I'll look into room conditions since that can effect LF.
My newest amps are Dynaco Mark 3's which I totally rebuilt with stiffer power supplies and diytube driver boards plus a tubes4hifi preamp.
The dynamics and bass definition is good, just this slight problem remains.
Gary