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Altec 414z enclosure guidance

I'm expecting to run into these kind of phasing issues on my build, too, Aaron. I'll be watching carefully to see how this is resolved. And thanks for posting the audiocheck.net reference. I wasn't aware of this site, but I have a feeling I'll be needing it until I get my hands on some decent test equipment.

GeeDeeEmm
 
Update: I went ahead and removed the 6uf cap and 8 ohm resistor, which were paralleled, and placed in series with the + of the horns AFTER the L-Pad. Removing the caps and resistors resulted in stock N-800F networks. That change completely fixed the phase issue.

I believe the cap/resistor should have made connection with the - side of the HF circuit somehow (as in the 30923), but I'm not sure how, so I'm leaving them out until I get the 30923 network installed.
 
Awesome! I'll def be following your build thread!

As far as the cap and resistor go, I got the idea to try it from the Skywaverider/Zilch 9844 thread (start toward the bottom of this page: http://www.audioheritage.org/vbulletin/showthread.php?18913-Altec-9844-8B/page3), in which Zilch says to take the 6uf cap, parallel it with the 8 ohm resistor, and put the two in series with the HF. A few posts down from the link I pasted, at the top of the next page, he refers to it as a contour network, and makes passing reference to the cap/resistor combo being the same as having the model 19's attention network fully attenuated. This was into the 8ohm HF load of Skywaverider's 9844b's, so I figured going with the same values into a 16 ohm HF load would be roughly like having the attenuation knob at 12 o'clock. I think that's still roughly correct, but that I didn't implement the cap/resistor combo into the circuit correctly. Regardless, I'm gonna get the 30923 in as soon as I receive the parts.

While the mids are now a bit more forward than they were previously at times, the sound is really just outstanding. Simultaneously revealing and rich...clear to me why they'd be popular in well-treated studio environments...particularly for tracking and mixing. I love the absence of a "modern hi-fi" quality to their sound... Yet they're obviously higher 'fi' than any speakers I've yet owned.

I've been leaving them playing at low volumes almost continuously, as I'm also breaking in some Arizona Blue capacitors I put in my amp over the holidays.

I'm still gonna do the YouTube video. I may do one now and one after I put the 30923 network in.

Where do y'all want the L-Pads set for the videos?

I'm anywhere from 5 (50%) - 8 (~85%) on the HF attention knob right now. I'm seeming to get more usable range on the dial as I get some hours on the new networks.
 
As you noted earlier, not a lot can be gained from listening to a system on utube, but they certainly are fun! If you get a chance, move the l-pads around a bit and let's see if we can detect a difference. I'll be listening on my Altec Lansing computer speakers/sub! They are very old, but sound very good.

GeedeeEmm
 
Ok... Another minor issue. I'm getting slight, but discernable, distortion from one of the HF drivers. It's essentially only audible during quiet passages of only HF, as in, pure, quiet tone of a trumpet, or other isolated, quiet HF passages.

I carefully removed the rear cover, tightened the screw terminal and diaphragm screws a bit and check the +/- leads... everything appeared unmolested. Result was slightly more noticable distortion from that horn, yet still not really discernable during louder or busy passages, i.e., the distortion seems to occur at a particular frequency range... But what do I know?

I already called Bill at GPA, and they can do their thing on both 806a's at a criminally low price, but thought I'd check here as a last resort, because as I've mentioned elsewhere in thread, patience does not come to me naturally.

Any tips? I was surprised that securing connections, and the diaphram screws, per GPA's instructions, didn't fix the distortion issue, because the sonic nature of the distortion to MY EARS is mechanical... not electrical... It isn't static.

Hopefully there are some pro audio guys here who can chime in and help me not feel crazy for expressing it that way.
 
Have you tried cleaning the VC gap? I forget if you mentioned doing that. There could be a little piece of crap in there
 
elitopus said:
Have you tried cleaning the VC gap? I forget if you mentioned doing that. There could be a little piece of crap in there
Click to expand...

This. And inspect the diaphragm and its voice coil for any signs of rubbing, separating or any other distress.

Out of curiosity, what source were you listening to when you noticed the distortion? (I ask because the other day I was doing some shop work and noticed my shop speakers doing some odd distortion in one of the tweeters. I was listening to FM radio. Duh! Changed stations and the distortion went away.)

GeeDeeEmm
 
Very true about the separation. There was a post recently where the OP was getting some distortion also. He took the diaphragm out and it was separating where the surround joins the dome.
If thats the case I would send both of them to GPA for new phragms and a recharge.
 
elitopus said:
Have you tried cleaning the VC gap? I forget if you mentioned doing that. There could be a little piece of crap in there
Click to expand...

I have not done that...unless you mean the opening that faces the horn, in which case I did clean that area out with masking tape wrapped around a marker.

If you mean the operation that is described in the GPA diaphram repair pdf, which talks about using a folded piece of tape around the tiny gap between the diaphram and the magnet, I have not...I'm not clear how (or if) one goes about that operation on the 806a.
 
gdmoore28 said:
This. And inspect the diaphragm and its voice coil for any signs of rubbing, separating or any other distress.

Out of curiosity, what source were you listening to when you noticed the distortion? (I ask because the other day I was doing some shop work and noticed my shop speakers doing some odd distortion in one of the tweeters. I was listening to FM radio. Duh! Changed stations and the distortion went away.)

GeeDeeEmm
Click to expand...

Do you mean the area around the outer circumference of the diaphram, where it comes into contact with the compression driver body? Would separation be clearly visible with only the back cover removed, or do I have to remove the diaphram also?

I haven't been able to find anything online that outlines the disassembly steps one would through to inspect/remove/reinstall the diaphrams to unsure they're ok.

To be sure I understand you all correctly: are you saying that the distortion could be due to the diaphram being improperly seated in the cd body?

I first noticed the distortion in the first ~24 bars of U2's "Where the Streets Have No Name"...some of the synth pads on the left channel were distorted. It reproduces the distortion consistently on that passage and a few others I've tried with quiet passages around that same frequency band, e.g., the trumpet in the opening bars of track 2 on the first American Football album. Streamed from Tidal through a DAC. It seems as though only a certain freq range distorts, and it's not nearly as noticable during busy/loud passages, but it's def there.

I'm willing to crack the cd open/remove the diaphram and take a look myself... Just not sure how to go about it...worst case I screw it up and have to send it to GPA.

Thank you all so much for sharing your experience with a complete novice!!
 
Yes and yes. Cleaning with folded paper and a thorough inspection of the diaphragm.

You could also prove its the diaphragm or driver by swapping in the good diaphragm. Or swapping the suspect diaphragm to the other driver
 
UPDATE: ok... Now I get it. Read over the GPA diaphram replacement instructions again... Now I see I need to remove the fram/voicecoil assembly, THEN clean the voicecoil gap, which is only accessible after the fram/voicecoil assembly is removed.
 
Ok... Took the cd apart, cleaned the voicecoil gap, and upon reassembly, realized the black Bakelite threaded binding post for the spade connectors had cracked and was falling apart (the bottom right one in the pic below, before a chunk came off)..

Probably from being over tightened at some point.

I attached the spade using the binding post directly above the broken one, reattached the cap and fired it up again... Exact same distortion as before.

I packed them both up and sent them to GPA.

Should have them both back in a week or so... Wish I had sent them off at some point during my 90 day build when they were just sitting there.

The 414zs are really starting to wake up and round out from about 300hz on down. Even with one of the cd's not performing to spec, the whole system was sounding very very good.

I'll get the 30923 networks added and cd's reinstalled in a week or so and report back!

Until then, I'll be catching up on GeeDeeEmm's build!
 

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Sorry to see this turn of events. GPA's turnaround time is pretty good, and you know things will be right.

Things are busy in my world so my posting opportunities are limited. I've gotta catch up on GeeDeeEmm's build, he's also headed in a pretty rewarding direction and will have some substantial speakers when he gets it worked out.
 
How'd the voice coil on the diaphragm look to you, Aaron? This is a curious one. Hope GPA tells you what they found wrong. I'll bet something is becoming delaminated around the voice coil, but the area is so small that it's making itself known only on certain harmonics.

Hope I can keep you entertained in the meantime. I'm hoping to pick up a little mdf today after my doctor's appointment. I tripped over a cement block one night last week, fell face forward, and broke a rib. It didn't bother me for several days, but the last two I've been extremely sore. Breathing feels like being stabbed in the ribs with a knife!

GeeDeeEmm
 
gdmoore28 said:
Hope I can keep you entertained in the meantime. I'm hoping to pick up a little mdf today after my doctor's appointment. I tripped over a cement block one night last week, fell face forward, and broke a rib. It didn't bother me for several days, but the last two I've been extremely sore. Breathing feels like being stabbed in the ribs with a knife!
Click to expand...

Sounds painful! Hopefully the doc can get you all fixed up. It sucks with rib injuries, you pretty much just have to take it easy until it heals.
 
elitopus said:
Sounds painful! Hopefully the doc can get you all fixed up. It sucks with rib injuries, you pretty much just have to take it easy until it heals.
Click to expand...

Just back from the doc. Confirmed broken rib, and she's sending me for a CT scan because of some "nodules" on both lungs. Danggit. Something else to worry about.

Sorry, Aaron, for drifting away from the subject at hand! I'll try to restrict myself to speaker issues henceforth.

GeeDeeEmm
 
gdmoore28 said:
I tripped over a cement block one night last week, fell face forward, and broke a rib. It didn't bother me for several days, but the last two I've been extremely sore. Breathing feels like being stabbed in the ribs with a knife!

GeeDeeEmm
Click to expand...

Sorry to hear this, hope recovery is fast for you
 
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