Please help my A7-500 's come alive

[stevelubker]

Hi all,let me introduce myself.My name is Steve and I reside in a small town just north of Toronto (Canada)]I am a Toronto firefighter by day (and night)and a cabinetmaker by trade.Fell in love with Altec when I was 15 or so.A friend of mine had a dad who was in a gospel band and I helped him set up in various churches..he had A7's and I couldn't believe how they could so effortlesly fill a church with sound..heard a pair of 19's in Sears one day (yes Sears but at the time we called them Simpsons Sears)once again an impression to say the least...so my Altec friends here is the reason I write to your board...About 5 years ago I built a pair of 825 cabs with matching cabs to hold the 511 B on top.I can assure you of heavy bracing and utmost attention to detail as I had a set of Altec plans that I adhered to....Drivers ??? A new old stock 5158G..old 9028a's that I put a brand new set of diaphrams that I got from GPA (Bill is such a nice guy)511 horns and a set of N85008A crossovers that I got on ebay...these are switchable for 500 or 800 hertz...ok lots of labor and bottom line ...hate em...lots of top end but no punch and the middrange...well hollow??bottom end..nothing..my port as per Altec specs is 26 x 8 and as I have read I need 75 sqare inches....well way off that..can't believe that there would be such an impact on that but will try...could crossovers be a problem??...seems that the 5158g's are not working ....even at high volumes the excursion on the drivers never excede a sixteenth of an inch ...I understand that they don't need to move that much to achieve resuts...I am not a electronics wis I am a lover of music and a guy with 25 years plus years of wood working experiance ...help please??

[dgwojo]

Maybe try a different amplifier or receiver, preferably one with a "loudness" button. Unseen this is hard to debug, it almost sounds like the 515-8G spiders or surrounds have stiffened up, I like the black spiders best on the 515B woofers, the brown ones are much stiffer, I think the G version uses brown. Since the 515-8G is not an alnico magnet woofer, you probably can't have it recharged, on a related note, were the woofers dropped causing the magnets to discharge? Maybe by-pass your crossovers to see if they're the problem. Keep us updated, good luck, Dave.

[jnorv]

I tuned my 828's at about 38 Hz with a 9x9x13" long duct. Works grat for me.

Jim N

[dgwojo]

re: "Maybe by-pass your crossovers to see if they're the problem" - I mean to bypass the crossover to wire direct to the woofer from the receiver/amplifier, never to the horn driver!!

[Fitts]

Steve,

Be sure to do the by pass test that dgwojo mentioned just to rule out the crossover. I would suspect that first and foremost.

Do your 515 woofers have ALNICO magnets or ceramic? If they are ALNICO they may need to be remagnetized based on the symptoms you describe.

Another test you could do is to either borrow or buy an Altec 416 or and EV Force 15 and put it in one cabinet to do an A/B test. I have used both the 416 and the EV with good sucess.

If the spider is too stiff, I don't know what could be done but would love to hear from the audience as to any cures.

Regards,

[stevelubker]

Hi all and thanks for the reply's..my 515's were factory fresh in origional packaging when I received them..no dents or tears in the box so I assume they were never dropped..magnets are ceramic as they are of a later vintage..surrounds are black...these drivers are in pristine condition....I did the test of by-passing the crossovers and there was no change...was surprised however how high those 515's could actually go..Currently I am running them on an NAD audio visual receiver...yup I know how to turn off all the digital effects...previously an old NAD reciever and yes I could get those drivers moving but only with the loudness button on..I do understand that these won't go much below 50 hertz...that being said I remember that it didn't matter...you could hook up a Radio Shack amp and cheap turntable and the sound was ...well ..Altec...I guess my next try will be to tune the ports and maybe find an old amp with a "loudness " button and I am being honest about that button...will keep you all posted and thanks again for all the help...Steve

[LICORNE]

I WOULD NEVER RUN AN ALTEC SPEAKER ON A HOME RECEIVER AMP.INVEST YOUR MONEY IN A COMMERCIAL AMP 3X THE WATTAGE RECOMMENDED FOR YOUR A 5.I SUGGEST HAFLER , CROWN , MCINTOSH , QSC, BGW,,AMCRON,ASHLY,CREST AUDIO. CANADIAN BRYSTON.
BE CAREFULL NOT BLOWING YOUR SPEAKERS.

[LICORNE]

If your into loudness buttons you should try aphex 204 aural exciter big bottom. The standard of the industry with over one million channels sold.
regards

[homme_de_terre]

I haven't tried it but some people claim the A7 likes amps with higher output impedance. Since it's easy to do it might be worth a try. Just connect a resistor 15 - 50 Ohms in series with the speaker. Of course you'll lose power but that might not be too much of an issue given the high efficiency of those speakers.

Manfred

[Art J.]

Hello Steve, Welcome to the group. You must have gone through a lot of work
building the fine cabinets, so I had to send you some encouraging words of
support. It seems that the speakers need a complete going-over from the
bottom up to get everything adjusted properly. You will need an Audio Oscillator
and some meters. Port tuning and Horn output adjustments should make it fine.
Maybe you can find a local hobbyist with the test equipment you will need
for all the procedures. Also if you have a good Amateur Radio Club
in Toronto, they can be very helpful too with equipment.

Now in the short term I would suggest finding a ten band 'graphic equalizer'
that installs in your tape loop. You can find them pretty cheap around.
They are a real handy tool to see how much attenuation and contour
you will need in the higher frequency ranges to match your room.
This will help you adjust, live with and enjoy your speakers until the permanent
solutions are in place. The equalizer may cause a little horn honk from phase shift
but this is for temporary use and testing only.

Do you have a digital camera? I'd like to see the cabs you made.
Its easy to post us a picture no hassle using this link.

http://www.uploadimages.net/index.php
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"Doctor, Doctor!, My horn rings like a bell
when I hit it like this!"
Doctor : "Well then, Don't hit it like that"