2way medium sized CD based altec/jbl build ideas/?'s

[Sean.m.miller1]

Always good to experiment with different bracing/damping solutions- there's no silver bullet there that will always produce the best sound so a willingness to trial it out there is helpful.

As far as the port depth goes, I actually have no idea, though I'm sure someone here can answer the question. I've definitely seen ports that have some extra depth to them, but never played around with it myself. Could be worth getting one of the cab modeling programs floating around out there and try putting some of your measurements in there and see what they spit out.

As far as crossover goes, one of the reasons the 414 is so beloved around here (and elsewhere) is that it can be run without any crossover components needed. I'm not sure what the stock Altec crossovers looked like for your speakers, but the classic 414/802 combo usually only features crossover components for the 802- namely a capacitor to determine the lowest frequency it will play at, and/or resistors to damp down it's efficiency to match the 414.

So you could always try scrapping the stock crossover and just putting a single capacitor in line to the CD. You can always put the crossover back in if you want it, though I'd guess you'll be better off without it.

 

[Aleixo_Camara]

applied this adhesive backed foam.....sounds pretty nice, not too different than stock insulation batts but it did change things a bit. Id say it improved mids more than it affected the low end But its hard to say for certain.




if anyone can help with these questions:



- switched from stock 800f crossover
to this single cap .

And more importantly, Got rid of the unused 'pseudo passive radiator'. And that was what was causing the problems.....Now much nicer. Damn nice even,

So first I swapped the new 'crossover' (4.7uf) in, and nicer mids but still low end issues...... Then Got rid of the unused 414 and blocked off the hole. And that is what did it... night and day difference. These are sweet now. who woulda thought

 

[Aleixo_Camara]

Was playing 4 different 414's out of the cabinet, just sitting on top of it, in order to see how they vary from one another....significant variation, but all similar 'sound signature'. In any case, this speaker sounds much nicer out of the cabinet. Apart from anything low mid and below of course. And sounds just as nice in back of cone as it does up front........And so now the itch to put a pair into open baffle is on....Apparently if one uses 2x12 rather than one 414, this increases the sensitivity by 6 db? Which may offset the loss in sensitivity from moving them out of a cabinet?

 

[RPMac]

Was playing 4 different 414's out of the cabinet, just sitting on top of it, in order to see how they vary from one another....significant variation, but all similar 'sound signature'. In any case, this speaker sounds much nicer out of the cabinet. Apart from anything low mid and below of course. And sounds just as nice in back of cone as it does up front........And so now the itch to put a pair into open baffle is on....Apparently if one uses 2x12 rather than one 414, this increases the sensitivity by 6 db? Which may offset the loss in sensitivity from moving them out of a cabinet?

Do it!
414 in OB is magical!!
Been listening for 2 year….and won’t ever go to a box. You lose some on the bottom, but it needs help there anyway.
I was going the same direction you are looking, but when my second pair of Z’s came in, the person put them in the box face to face. Which is fine, if you BOLT THEM TOGETHER! So I ended up with one busted cone.


I needed a moment…

Two 414s will match better to the stronger 802 type CD. I have 807s to try to match better with the single 414. All I want is a single capacitor crossover for the 807 and nothing between the amp and 414.
A pair of subs and you are good to go.

 

[Aleixo_Camara]

all that guy needed to do was zip tie the two frames' faces together....that sucks.....Are you using a real sub or a movie theatre type sub?

It sounds like you have no inductor on the low end of the 414 and so it is rolling off naturally? and you just add the sub with its own crossover point? around 100 hz? If so, that would mean both the sub and the 414 are overlapping alot from 80hz to octave or two above correct?

I milled up some 2" thick white oak today and glueing up the panels...Will be about 80 lbs each... I made a sound clip on youtube of the 414...so nice. Am interested in getting to hear these outside the box...the box sound really is a problem . Its a small room which doesnt help. so the open baffle is sort of like using the room as a cab of sorts is how Im thinking of it.....The compliance of the fragile 414 surrounds might really match an open baffle (except the fast and early low roll off which im aware of)......I suspect that when they are in the standard closed cab, the back waves are slamming right back into the cone/surround, and that is in large part, the problem as to why the bass and low mids are congested and unorganized. Add that to the 'box sound' and it's really not using the 414 to anywhere near it's potential, as can be heard just listening to the open air driver....will see...

 

[RPMac]

all that guy needed to do was zip tie the two frames' faces together....that sucks.....Are you using a real sub or a movie theatre type sub?

It sounds like you have no inductor on the low end of the 414 and so it is rolling off naturally? and you just add the sub with its own crossover point? around 100 hz? If so, that would mean both the sub and the 414 are overlapping alot from 80hz to octave or two above correct?

I milled up some 2" thick white oak today and glueing up the panels...Will be about 80 lbs each... I made a sound clip on youtube of the 414...so nice. Am interested in getting to hear these outside the box...the box sound really is a problem . Its a small room which doesnt help. so the open baffle is sort of like using the room as a cab of sorts is how Im thinking of it.....The compliance of the fragile 414 surrounds might really match an open baffle (except the fast and early low roll off which im aware of)......I suspect that when they are in the standard closed cab, the back waves are slamming right back into the cone/surround, and that is in large part, the problem as to why the bass and low mids are congested and unorganized. Add that to the 'box sound' and it's really not using the 414 to anywhere near it's potential, as can be heard just listening to the open air driver....will see...

The 414Z/32C/807 is wired the same as your diagram except with 7.2uF(807 is 8ohm).
I use 2 Dayton plate amps on the 605B woofers in the H-frames with crossover at 40hz or just above. The volume is just enough to know they are there.
The plate amps and the 300B SET(driving the 414Z/32C/807) ,once matched, have their volume controlled by the preamp.

 

[IceRover]

I have Altec A5s with 1505b horns and 604-8g coax in 620 clone cabs ( and 18” subs). You could go another route i.e. use 8” fullrange (ex Lowther pm4a or similar) in a large front horn down to ca. 150Hz and a pair of 15 or 18in woofers per side in open baffle or SLOBS.

 

[Aleixo_Camara]

very close now..the 414B's are in a 604 sized cab (3cuft), made with the old 9844 cab materials. Back panel is glued in stock particle board. Baffle is 2" thick solid poplar- a quite none resonant wood imo, rabeted, inset and woodglued in. Inner stuffing is the same as prior. so only real change is the new cabs. They are quite rigid and airtight now. That must have been what made the difference. I'd say the 'boxy' sound is 90% gone now. Only things left is to determine a port length for the 2" pvc (maybe 3-6" or so), and try a few more damping materials and maybe an internal angle divider... This is a keeper now. I'd say bass is comfortably down to 45hz. crossover is 8uf cap on treble, which i believe starts at circa 3500hz - that's it. night and day improvement from the bone stock 9844. To my ears, that speaker was not meant for home stereo replays, at least not in this room and to my tastes.

the other set of 414's will go in the open baffle build..

 

[Aleixo_Camara]

couple weeks of messing with batting and insulation of various kinds, as well as port lengths...ports where fairly easy to hear and ended up with 2" x3.5" (x2 openings per cab). Tried everything from zero length to 11" (22"effectively)

the batting was a different story. Took alot longer and ended up with what may be unconventional enpoint. (very little batting). Tried nearly every permutation from back, wall, bottom to just back, just wall, etc etc and ended up with one vertical polycotton (taken from cheap pillow - favorite of all tried), oriented perpendicular to driver, just hanging down off a couple screws in top of cab.

Dramatically improved over all other attempts that used more batting. With more insulation, the bass got duller, les defined and didnt go as deep...once the batting was out and that one piece in. bass effectively extended down another 5-10 hz i'd guess and to my ears could be into the 30's at this point. see recent vid clip- taken with $75 phone that does not do well at audio or video but.....) .. bass is now very defined, taut, articulate, toney, natural..very nice...the mids did change a bit throughout this process but recouped alot taht was lost with the perpendicular cotton drapery...this may be the end point....

Not that i'd think of going back to adding insulation just because technically it may be correct? but if anyone has any info or idea as to why the solution here is somewhat unconventional, i'd be interested just for edification purposes. Or maybe removing most of the batting is not that rare. not sure but havent heard of it so far..

 

[Aleixo_Camara]

could use some input
So at low volumes this is easily the best sounding stereo/speakers have heard. Literally no issues to be solved there.....The problem continues to be when its turned up to anywhere past low/medium volumes....quickly gets disorganized, murky, and boom in low end and low mid...- have been using the single cap crossover on the tweeter anywhere from 1500k-4500k (preference is towards the higher end as this keeps any beaming or honk from the tweeter from appearing)(using no horn fyi so this undesirable quality is from the 808/806 itself - horns only amplify this issue, and am very content in small room with no horn. The detail is only mentioned for crossover concerns below - also this issue is secondary to the 414 bass/volume issue)..

So trying to figure out why the bass goes from perfect to quite unlistenable with moderate volume increase. In attempt to start determining this, Tried adding the appropriate mH inductor on the positive lead on the 414. This is supposed to start removing the driver from the circuit, whereas without the inductor, the 414 mechanically continues until 4-5000hz where it trails off on its own..In adding this inductor, it does help significantly.

The question is whether moving to a 2nd order butterworth would further help the issue or not...Before deciding on crossover frequency and whether to try 2nd order due to parts cost...the only other cause for the low end issue when volume is added could be cab related (batting) or room position, but if that where true, why does the bass (and everything else for that matter), sound so perfect at low volumes...

so due to the improvement when adding the inductor, am currently leaning towards trying to massage the issue away with the crossover...?

also, the concern with going to 2nd order is that some of the best traits loved now at low volume would be lost due to inherent issues with 2nd order....also the crossover point would have to be lowered no? or else how would the issue be solved if it is in fact coming from the upper end of the 414 being disorganized(say 1500 and up (unless the problem is caused by the very top of the 414 -4 or 5khz and above - which would be great if true, but seems unlikely no?)

...so if the crossover was lowered from say 3500hz as it is now, to say 800hz, then the bass issue may be helped but now the lower end of the tweeter is coming in more, which tends to bring with it undesirable beaming/honk as well as losing the desirable qualities of the upper end of 414 which i prefer over the lower end of the 808/806. So since at low volumes, the top end of the 414 sounds perfect and would like to keep, that is the dilemna in wanting to keep the 414 either running full out or at least with a high crossover point.

the only inductor on hand is the 3.5 mH taken from 800F crossovers, so that is what was used in above experiment. which puts crossover 800hz and that is the only reference ive heard when i mentioned the benefits from adding an inductor..so when buying inductors to try in future, id have to buy several that are appropriate for say 2500hz to 4500hz cross points, and the concern is that it may not be low enough to solve the issue and soon will end up with $100's worth of unusable inductors...if it wasnt for expense id just buy a bunch and try, but am asking for ideas to try and avert that....
.

 

[Phillip Jeffries]

What I’ve found with the Altecs, my setup is 419-8b, 802-8G, 32b, is that more volume doesn’t really intensify the experience. I’m very grateful to have found a setup that can recreate the experience at sane levels.

I had a set of Linn speakers that was the opposite…sounded pretty flat at normal volumes, but really sounded fantastic at, shall we say, concert volume. You always read people say, “these speakers need a lot of watts to wake up,” and it makes me want to run away!

But, it could just be the nature of your room…you turn up and the room gets a bit boomy.

If you want to experiment, I’m a huge admirer of the altec style series crossover. There is an additional coherency…maybe smoothness…to the series crossover. I don’t really understand it, but it does seem to clean up the sound a bit. I can see both sides…that no crossover might sound a bit rawer like live music…and the series crossover kind of cleans up the sound…like well reproduced music.

When I was messing with my Heresies, I had the series crossover at about 2900 hz…it was literally higher than where the woofer rolled off naturally, but it still did something to the sound that improved it.

For some reason, at least with the inductors I have on hand, I gravitate towards the bessel Q. The altec series crossover, I think is second order on the woofer, but first order on the horn. Is that right? Like I said, I don’t fully understand it…!

 

[Aleixo_Camara]

the low volume experience is by far the best i've heard. Was not expecting that. It is very realistic even at just over tv volume. When turned up, this is the only speaker that makes the cat dissappear...same with when we rehearse as a band. which I suspect is a testament to the dynamics and realism. So yes, if push comes to shove and had to live with altecs at low volume, might be fine. It is a new way to listen. low volume but with realism and dynamics is somehow relaxing and yet involving....will look more into series vs parallel and first vs second order.....may have to buy a bunch of inductors and try several crossovers....

a side observation...CD's have never sounded so good. Have never had a system that allowed for CD enjoyment, for whatever reason, but these speakers allow it to work...not sure how or why, but is another unexpected bonus...so maybe between that and the very nice low volume experience is enough to outweigh best sound at higher volumes...everything is a tradeoff and If I got the system perfect at high volume, maybe would lose some or all of the prior two benefits....will try and get it better at a little higher volumes and then call it good, most likely...

 

[Aleixo_Camara]

anyone know what series this original aluminum diahgram is? (it might be a 34852 but if so, it sounds quite different from another 34852 I have, but that one does not have the red gasket so that is why I assume it may be something else....the one in question is in a stock 806/16

the distinguishing visual characteristic AFIIK is the red gasket paint. I'd rather not disassemble to find out what the numbers are, as this is one of the better altec drivers i have and would rather not fiddle with it..

fyi, the four digit code on back of the drivers cover is 1226 if that helps dating it...not sure what those 4 digits refer to ....

 

[EarlK]

Original diaphragm ( model ) to the 802A + 806A is the 20275.

The 34852 model is quite a bit newer ( introduced in the mid 1970's I think ).

I thought that all 34852's had push-on tabs for wire connectors .

 

[Aleixo_Camara]

Original diaphragm ( model ) to the 802A + 806A is the 20275.

The 34852 model is quite a bit newer ( introduced in the mid 1970's I think ).

I thought that all 34852's had push-on tabs for wire connectors .

the other known 34852 i have does have the push tabs. so if that is in fact a feature of that model, that may rule it out for the one i'm trying to learn about...I thought i'd read that the push terminals was a time period feature (later) and not model specific? but maybe all the 34852's where in that particular time period and so all may have push terminals?

in any case, am searching 20275 and found these, that also have the red gasket paste, and similar white lettering - 'L 1' ? ...so maybe that is what it is...

altec 20275 - page 1 | WorthPoint

altec 20275 in the WorthPoint Worthopedia® Price Guide, page 1 of 1

www.worthpoint.com

appears that driver must have come out of a 604 duplex ? if so, wonder how it ended up in a 806 driver



but here is one by jelabs that also has the white lettering L1 but maybe no red gasket paste, and he seems to have it as being

34647

 

[IceRover]

I currently have a killer two way + sub.
Celestion axi2050 in SEOS 30 on top of my old Altec 828 cabs with GPA 515Cs. Single jbl 2242h in bass reflex as sub using inexpensive minidsp for the sub. I have not optimised at all just exchanged the axi/Seos combo in stead of Altec 1505Bs with Altec 299-As. Sounds clear as water and more dynamic than before. I will be testing fully active soon and play with dsp with a minidsp flex eight.

 

[jblnut]

You're on the right track when your speakers are larger than your TV :-)