I forgot how heavy MDF and particle board can be.... Altec 9844A

[kcdonahue]

I picked up pair of 9844a a few weeks ago and haven't had much time to play until the holidays. I gave them a quick visual the evening that I brought them home and they looked good and measured generally as expected given that the crossovers were modified. Getting the cabinets into the car and into the house was no problem at all, but once I grabbed one of my boys to help me get them down the basement, that is when the weight of these things became immediately apparent.



Once they were successfully in the basement I had to figure out where to put them. Since they were the new toys in the basement I put them on top of my JElabs/JRob work in progress so I could at least wheel them around while I further checked them out. I pulled the covers off of the horn drivers and they are at least original Altec parts. It also looks as though the woofers were replaced at some point since they look like later models, have no dates codes or they are dated differently, and by the fact that there are extra screw holes in the baffle, but I could be wrong...



I also pulled the crossovers to see what was going on and the pots were replaced with a 20R resistors, which I left in for now. I fired them up on a few different amps including a 300b, DG SEP magnavox, and a 60 watt Lm3886 chipamp and I am pretty happy with the way they sound with each amp. Next up is a quick rewire to see what I can do with them bi-amped using the minidsp that I have setup for my A7s. So far, I prefer the upper end of the 32b with the 414z combo but they also play much higher due to the phrams installed, but the bass of the 9844a is very nice and articulate and only a little glare from the 811s. Now I really need to get my act together and get at least one of my Altec projects to the point where it is at least done for a while as I'm running out of space to move them around! Not complaining though...



Happy holidays!!

KC

 

[Tom Brennan]

Outstanding speakers. I had Heathkit AS-21s which were 9844s in furniture cabinets. They had a very smooth and detailed sound with a very lifelike midrange. The 414 is a boss driver.

 

[bowtie427ss]

You have a driver sensitivity mis-match that didn't exist originally. They likely removed the pot in an attempt to squeeze a little more out of the 806 to get the system in balance.

The ideal correct answer was a 902 and shifted crossover to 1200hz, or even an 802 would work with the stock XO while giving a few more db sensitivity. But, a more sensitive HF driver is what's really needed to keep up with the increased sensitivity and upward shifted response of those 414E's, they play louder/more sensitive than any of the alnico 414's, we're talking several db difference.

With an 802 or 902 HF the upper half of the Nineteen network can be used to further EQ/smooth the VHF and enjoy model 19 performance above XO.

If Mr Brennan shows you a pic of the open back of one of his AS-21's, you'll see that he's no stranger to swapping the 806 out for 902.

 

[kcdonahue]

You have a driver sensitivity mis-match that didn't exist originally. They likely removed the pot in an attempt to squeeze a little more out of the 806 to get the system in balance.

The ideal correct answer was a 902 and shifted crossover to 1200hz, or even an 802 would work with the stock XO while giving a few more db sensitivity. But, a more sensitive HF driver is what's really needed to keep up with the increased sensitivity and upward shifted response of those 414E's, they play louder/more sensitive than any of the alnico 414's, we're talking several db difference.

With an 802 or 902 HF the upper half of the Nineteen network can be used to further EQ/smooth the VHF and enjoy model 19 performance above XO.

If Mr Brennan shows you a pic of the open back of one of his AS-21's, you'll see that he's no stranger to swapping the 806 out for 902.

Thanks for the confirmation! I just dug out the two pairs of 902s that I have, ohm'd out the phrams and measured the apertures with a pair of calipers for the heck of it. The pair with the with factory rubber bumpers and metal rear covers have one inch apertures and are 8 ohm. Had to double check the throat with a bright surefire flashlight due to the bug screen. The other pair it is pretty easy to see the difference by the shiny circle showing through the bug screen (right).



I will wire them up for bi-amping so I can play with the minidsp until I buy some parts to build some crossovers.

 

[bowtie427ss]

You just took it up many notches!

 

[Tom Brennan]

f

 

[bowtie427ss]

Thank you sir!

Please pardon my mental inventory of your loudspeaker history.

 

[kcdonahue]

Huge thanks for the input gentlemen!

I got a few hours to play with the 9844a’s this evening. To start off, I replaced the 806s with the 902s using the existing crossovers. The improvement was immediately apparent and they were way better balanced. I should have stopped here but…

Since I had the time I also went ahead and rewired them for bi-amping using the minidsp. After my initial listen, I have to say that the 902-8a’s are way more sensitive than the 806 or 808s that I have used on other projects. I had to pad down the horns by -13db on the minidsp to get them somewhat in line with the woofers. Judging by the fact that specific guitar solo’s seemed to be way forward, I likely need to pad down the horns further. I was using the cable for my UMIK microphone to run the minidsp and did not use pink noise to get to this point, which is something I plan on exploring tomorrow to better match the levels.

To be fair, the 300b amp I used for my woofers did not do me any justice as it only has 16 ohm outputs on an 8 ohm load of the dual 414s, but I didn’t have to move anything in my rack to play around… I will try again tomorrow with a better matched and slightly more powerful amp on the woofers. The amp on the horns is a SE el84 and I plan to use a PP el84 on the woofers for my next try.

With the woofers/horns crossed at 1200hz with a sharp 48db slope the speakers were very in your face and harsh. I did not take much time to alter the crossover slopes, but I am planning to do some adjustments and listening tomorrow. Based upon my experience with the 414s playing wide open with the Jelabs setup, I pushed the crossover frequency up a few times and landed at 3700hz where things seemed to really smooth out. After using the 32b horns for a while I may be making things too smooth… Am I heading in the right direction here?

The 414s actually sound pretty decent with no upper end filter at all; letting them play until they roll off was pretty neat. They actually have more high end output than a few “full range” speakers I have used!

If it is not evident in my ramblings, I am relatively new to the ins and outs of crossover theory and design. In the past I have built a number of speaker kits and some more ambitious homebrew OB speakers/crossovers but I had lots of guidance and google. I am also slowing learning my way around the Minidsp and REW.

 

[twiiii]

Basically an Altec Carmel in an ugly box.You might want to try a N-1201 crossover to get rid of the honking sound of the horn and to improve HF performance. I changed the 806 driver for the improved 802 back in the 60's. If I knew then what I know now I would probably have kept the Carmels. With new diaphragms and cones and bi-amping with a mini DSP the sound should be amazing. Wonder how they would sound using the manta ray horn instead of the 811. Better I'm sure, the issue would be maintaining a flat high frequency response.

 

[WntrMute2]

You probably are aware of this so forgive if I am telling you stuff you already know. The woofers are supposed to be oriented close to the ceiling or the floor. I believe the 9844s were originally designed to be hung near the ceiling with the woofers closest to the ceiling. My Heathkits, which have the same drivers are floor standing with the woofers close to the floor. INOW, with your 9844s, you should have the woofers close to the floor and the horn at about ear level. I'm not sure where I got this info so take it with a grain of salt.

 

[kcdonahue]

Good point WntrMute2. I briefly tried them both ways and ended up with them like this until I get around to adding legs or more likely building a base that I can wheel around. Once I get to that point I will do my in room measurements with them oriented the other way. The 9844s seem to be heavier than my A7s loaded with woofers, pressboard and mdf vs plywood...

I haven't had much time since my last post to better match the tweeters with the woofers or do any audio stuff. Hopefully I can get down there and play later today.