411-8A replace by 421 Woofer

[arawak1969]

:banghead: Afternoon all
Can the 421 woofer replace the old 411-8A?

The reason is that I have been trying to locate 411's and have not had any luck.
I have not been able to find info on the 421 to see if it can be used in a sealed enclosure such as the 9846.
If it cannot be used, what replacement(JBL or Altec) do you suggest and what should I expect to change.
Thanks,
Peter:dancin:

[spkrman57]

Bill H at Great Plains can recone them.

421 is vented driver only. Also it does not have the LF extension of the 411.

Need more info to help out here.

Ron

[arawak1969]

Okay, here goes.
I found a pair of 9846's but they have a JBL 2225 woofers in excellent condition along with a 806 drivers on the 511 horns.
I do not have a an extra set of 411-8A's to put in them and was wondering if there was a modern woofer similar to the 411 that i could put into the sealed enclosure.
I am going to put the 2225's up for sale once I locate a replacement.
I can't think of what these will sound like with a vented woofer in a sealed enclosure.

[spkrman57]

How did the 2225's sound in them?

Ron



Okay, here goes.
I found a pair of 9846's but they have a JBL 2225 woofers in excellent condition along with a 806 drivers on the 511 horns.
I do not have a an extra set of 411-8A's to put in them and was wondering if there was a modern woofer similar to the 411 that i could put into the sealed enclosure.
I am going to put the 2225's up for sale once I locate a replacement.
I can't think of what these will sound like with a vented woofer in a sealed enclosure.

[arawak1969]

I guess my Dad was right. I never listen.

I got them in and immediately took the 2225's out so I can't even tell.:banghead:

[spkrman57]

Install the 2225's in them and listen and report back if you would please.

I had JBL 2205's some time ago that worked well in 6 cu ft sealed cabinet.

You never know, and it depends on the type of sound you are looking for if they would work out for you or not.

Costs nothing but time to find out!

Regards, Ron

[arawak1969]

Install the 2225's in them and listen and report back if you would please.

I had JBL 2205's some time ago that worked well in 6 cu ft sealed cabinet.

You never know, and it depends on the type of sound you are looking for if they would work out for you or not.

Costs nothing but time to find out!

Regards, Ron
I did the swap and was very disappointed.
Not anywhere as flat sounding:banghead: as the 411-8A's.

I have them up for sale and am looking for another pair of 411-8A's.

Anyone got any they wanna part with out there?
Peter

[GordonW]

The closest JBL woofer to a 411, is the 2235H or 136A/2231A. It may still not match sufficiently well for your taste in the mids (then again, it may)... but it's the closest thing, in construction, that JBL ever made to a 411...

Regards,
Gordon.

[Zilch]

Recone those 2225s to 2234s. Try that.

Not enough bass? Install the mass rings and make them 2235s.... :thmbsup:

[Earl K]

- I've always wondered what the "mms" is for this woofer ( 411-8a ) .

- Does anyone know or have a sample ( plus Woofer Tester ) that could be measured ?

- And while we're at it, does anyone know the BL figure for the 411 ?
( Altec was really miserly when it came to releasing these sort of technical details )

:)

[scott fitlin]

I have an Altec looseleaf at home with the spec sheet for the 411, but not sure it has that much detailed info on specs. I`ll look when I get home.

That woofer has a super compliant suspension, and goes down really low, medium efficiency, designed for sealed enclosures, I think.

The 421 series is not a replacement for that woofer. The closest thing I could think of, which has already been said, is the JBL 2235.

[yggdrasil]

Cannot remember where I got these, but...

[grumpy]

probably here :):

http://alteclansingunofficial.nlenet.net/proloudspeakers/lflit.html

[scott fitlin]

Thats the same literature Johnny posted, which is what I have.

I found it, here are the TS specs for Altec woofers! But not every spec, no mms or bl.

http://alteclansingunofficial.nlenet.net/Thiele-Small.html

[Earl K]

Thanks guys , but ;

- I'm still wondering about mms & BL .
- Altec,,, to the best of my knowledge never published those figures.

- Also, does this woofer use an overhung or underhung voicecoil ?
- And last, but not least; what's the depth of the gap ( top-plate ) ?

:p

[grumpy]

http://www.thielesmall.com/database.asp

...
xmax[mm]7,1
Moving mass[g]93,26
Bl[Tm]14,038
...

[CONVERGENCE]

QUOTE
411-8A replace by 421 Woofer
:banghead: Afternoon all
Can the 421 woofer replace the old 411-8A?

The reason is that I have been trying to locate 411's and have not had any luck.
I have not been able to find info on the 421 to see if it can be used in a sealed enclosure such as the 9846.
If it cannot be used, what replacement(JBL or Altec) do you suggest and what should I expect to change.
Thanks,
Peter


No Peter the 421 is an instrument speaker and the 411 is HI FI.

http://www.altecpro.com/pdfs/vintage/SpeakerAndMics/systems/9846-8A%20Speaker%20System.pdf

If you can find a 411 that would be best for the 9846 cabinet .
The 411 and 421 are both undurhung. The Gap ,Voice Coil ,spider and cone are different.

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

[Earl K]

Thanks Grumpy !

I wasn't aware of that web page.

That "lowish" BL figure ( by JBLs' & other modern manufacturers' standards ) is quite consistent with snippets of other posted info, that I've seen from time to time.

:)

[GordonW]

Thanks guys , but ;

- I'm still wondering about mms & BL .
- Altec,,, to the best of my knowledge never published those figures.

- Also, does this woofer use an overhung or underhung voicecoil ?
- And last, but not least; what's the depth of the gap ( top-plate ) ?

:p

If you put the parameters given into most box-calculation programs (such as Harris Bass Box or the like), the program will spit out a very close estimate of Mms and Bl, from the parameters given.

In the day the 411 was used, there wasn't really an emphasis on T/S-based design, by DIY enthusiasts. Hence, there wasn't much in the way of published parameters, except in cases where the manufacturer LATER went back and calculated/measured them and published them. Unfortunately, this time (late '70s to early '80s) was when Altec was in financial crisis, and being bounced to new ownership... so, the continuity of technical documentation was broken.

With an X-max (one way) of .28", the 411 pretty much HAS to be an under-hung woofer (ie, thin top plate and wide voice coil winding width).

Given how similar the parameters (.28" X-max, for example) are to the JBL 2235, I'd think that it'd be safe to use the woofer assuming that the gap height and such was about the same as the JBL (.28"). It might be different, but given the similarity of the parameters (all it'd take, would be a bit of extra mass added in addition to the normal mass ring on a 2235- maybe the equivalent of another THIRD of a mass ring in addition to the factory one- to make the 2235 act almost exactly as a 411, in box-calculations), I'd not worry about the difference, unless I was needing to recone a 411...

Regards,
Gordon.

[GordonW]

No Peter the 421 is an instrument speaker and the 411 is HI FI.

http://www.altecpro.com/pdfs/vintage/SpeakerAndMics/systems/9846-8A%20Speaker%20System.pdf

If you can find a 411 that would be best for the 9846 cabinet .
The 411 and 421 are both undurhung. The Gap ,Voice Coil ,spider and cone are different.

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

Holy cow! How thick IS the top plate, then? Like 3/4"?! It'd HAVE to be about that big, to make for a .28" one-way X-max (7.1mm), with ANY sort of a reasonable voice coil winding length (at least 1/4" wide winding)!

That'd certainly explain the lowish Bl figure... NO way to get much magnetic flux density in THAT thick of a plate!

Regards,
Gordon.

[Earl K]

Hi Gordon


Holy cow! How thick IS the top plate, then? Like 3/4"?! It'd HAVE to be about that big, to make for a .28" one-way X-max (7.1mm), with ANY sort of a reasonable voice coil winding length (at least 1/4" wide winding)!

That'd certainly explain the lowish Bl figure... NO way to get much magnetic flux density in THAT thick of a plate!

- Maybe the top-plate is 3/4 of an inch thick. The cut-sheet that Johnny posted does make mention of an "unusually deep gap".
- By Altec standards , I take that to infer a gap deeper than their regular .47" depth .


With an X-max (one way) of .28", the 411 pretty much HAS to be an under-hung woofer (ie, thin top plate and wide voice coil winding width).

- It seems to me that you may have meant to type "over-hung" . Yes / No ?



:)

[GordonW]

Hi Gordon



- Maybe the top-plate is 3/4 of an inch thick. The cut-sheet that Johnny posted does make mention of an "unusually deep gap".
- By Altec standards , I take that to infer a gap deeper than their regular .47" depth .



- It seems to me that you may have meant to type "over-hung" . Yes / No ?

:)

Yep... apparently couldn't keep it straight in my head today... and I don't even drink, so I can't use the excuse of being "over-hung" myself! :banghead:


Regards,
Gordon.

[moldyoldy]

411's are definitely overhung, 0.875" coil stack (accurate) and 0.41" front plate (awkward measuring position, possible minor error). Unless my plate measurement is ~ 0.1" long (possible), there must be substantial fringe flux (the right term eludes me now) to allow 0.28" peak linear excursion. While many of us do the plate thickness/coil height math to determine xmax, I think the true definition refers to operational linear movement, which can exceed the static assumption as long as there's sufficient fringe flux on both sides of the plate.

I saved the moving assy intact from a pair I reconed, and if I can find a gram scale to borrow, I'll weigh one. They're VERY heavy cones, I'd guess 3x or more the weight and thickness of a 515 cone.

The only other overhung Altec 15" I'm aware of was the short-lived 413, which was like the 411 in many respects, but used the standard Altec 3" coil dimension. Both were major tradition-breakers for Altec, who otherwise never "stooped" to overhung designs. ;)

The older Altec drivers (pre T/S) listed T/S specs were derived from test records. I'm a little dubious as to the derived data accuracy, as I've never produced a good matchup with measured data, though it's just as likely the fault of my measurement methods or the fact that the drivers are all ~30 yrs old.

[Earl K]

Thanks moldyoldy !

- Overhung it is then .

- Weighing the cone/coil assembly would give us mmd ( which is "mms" minus the air load / which is quite small ).

- Triple the weight of a 515 cone would certainly push the 411-8a into 2235 territory ( maybe more ).
- That would be quite a bit more than the mms spec. that what Grumpy found and posted . Very Interesting .
- FWIW ; I've seen Bill Woods quote TS numbers that seem to come from that web site. I wondered about them at the time since they state the 414-8C as having more BL than a 416-8C / which is quite unusual for woofers from within the same engineered family .



:)

[Earl K]

- Okay, this is for Peter, the original poster .

- Based on the info collected to date; this is my nomination for a modern substitute for the long defunct Altec 411-8a .
- Comparing to the 411, this woofer has a similar voicecoil & gap topology / as well as a commensurately heavy cone ( quite heavy actually ) . This gap depth ( & coil length ) is the closest I can find to the .4" deep gap which moldyoldy has measured. Since the TS parameters for 411(s) are suspect ( by many ) , I'll have to ignore the big differences between the two in BL , mms and Qts . ie; the motor assembly of this substitute may in fact be too powerful ( therefore, more like a JBL ) to properly place it into the Altec "recipe of engineered sound " . This is as close as I can find .
- This Sound Reinforcement woofer would still need some custom work done to it to turn it into a usable HiFi woofer. Namely, a higher compliance surround would most likely need to be installed ( &/or, maybe a smidgeon more weight added to the cone ) so that, Fs can be dropped to somewhere around 20 hz .
- You'll need the services of a talented reconer ( such as GordonW ) to do this type of custom woofer work for you.
- I haven't named the brand / you'll need to figure that out yourself ( from my broad hint ) if you're at all interested in this sort of modification .

:)

[grumpy]

I'm sure the thiele-small parameter web site would love to have updated
or corrected information in regard to the 411-8A (or any other drivers).

-grumpy

[scott fitlin]

Earl just out of curiosity would the TAD 1602 work? It already has a high compliance suspension, and a 21hz Fs, and a foam surround.

http://www.pioneerelectronics.com/pna/v3/pg/product/details/0,,2076_310070073_34199_tab=B,00.html?compName=PNA _V3_ProductDetailsComponent

[Earl K]

Earl just out of curiosity would the TAD 1602 work? It already has a high compliance suspension, and a 21hz Fs, and a foam surround.

- From what I see, TAD closely based the engineering of their woofer products, on JBLs' approach.
- Therefore, a similarity to a comparable JBL product is how I would expect this TAD woofer to perform. The 1602 appears to model as a 2234 variant ( though maybe a 136a is closer ).
- So if the sound of a 2234 is what one likes / then yeh the TAD is a workable LF woofer/ though the cone material is different which will show up as a difference in midband texture ( IME ) .
.
- Altec used very different recipes for their engineered approach. With that, they achieved different results in the texture and tactile sense of sound reproduction. DieHard Altec fans will always refer to those differences .

- From a longtime JBL users' POV , the TS numbers for Altec woofers are pretty dismal . Fortunately TS numbers don't offer up the whole story for HiFi ( as I've learned from owning and listening to deeper gapped woofers ) . :p

[scott fitlin]

.
- Altec used different recipes in their engineering approaches. With that, they achieved different results in the texture and tactile sense of sound reproduction. DieHard Altec fans will always refer to those differences .

:pThis is true!

But, I do like the sound of TAD woofers, in general. However, I agree if its that Altec sound your after, nothing else will sound exactly like it. For better or worse.

OTOH, that TAD is rated to get down almost as low, has a high compliance suspension, and could possibly be a similar type of bottom end sound. The only thing about the TAD woofers, I forgot to mention is that they are 16in frame drivers. The 416, 421, and 515 series of Altecs used 16in frames, but I have to re-look at the 411.

The 411-8A has an outer dia. of 15 3/4 vs TAD 1602 15 5/16.

[arawak1969]

This is true!

But, I do like the sound of TAD woofers, in general. However, I agree if its that Altec sound your after, nothing else will sound exactly like it. For better or worse.

OTOH, that TAD is rated to get down almost as low, has a high compliance suspension, and could possibly be a similar type of bottom end sound. The only thing about the TAD woofers, I forgot to mention is that they are 16in frame drivers. The 416, 421, and 515 series of Altecs used 16in frames, but I have to re-look at the 411.

The 411-8A has an outer dia. of 15 3/4 vs TAD 1602 15 5/16.

What do the TAD 1602's cost new or used?

[scott fitlin]

I have never seen the 1602,s on the used market.

They are expensive, the alnico magnet makes em cost.

[Earl K]

What do the TAD 1602's cost new or used?

- Certainly more than $ 500. a pair , used ( if they can be found ) .
- Used JBL 2235H or 2234H are typically a much better deal what with 2235H(s) showing up on eBay about once a season ( at the very least ) .

:)

[grumpy]

Here you mad-dogs go:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200088731795&indexURL=4&photoDisplayType=2#ebayphotohosting

Perhaps the seller could make some of the dimensional measurements that have been requested here...

-grumpy

[moldyoldy]

Here you mad-dogs go:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200088731795&indexURL=4&photoDisplayType=2#ebayphotohosting

Perhaps the seller could make some of the dimensional measurements that have been requested here...

-grumpy

No disrespect intended for the seller, but none of those listed appear to be stock 411s, and it goes beyond the shiny dustcaps...:(

[scott fitlin]

Not for nothing, but that cone looks more JBL than Altec.

[scott fitlin]

Look like a Frankenwoofer.

[Earl K]

In this thread over at Todds' Altec forum (http://www.hostboard.com/cgi-bin/ultimatebb.cgi/ubb/get_topic/f/3729/t/2753) ( also about Altec 411-8a woofers ), the owner of those eBay offerings is involved in a discussion about his "NOS" woofers.

[grumpy]

deflated bicycle tube (looking) surround and decal were all that looked familiar w.r.t.
the very few pics I've seen (Barcelona?) Cone in altec product sheet does -resemble- a
JBL type: http://www.voiceofthetheatre.com/images/4118A.1.jpg
(atsa lota ribs der...)

Interesting thread over there... thanks Earl.

-grumpy

[scott fitlin]

Yep, the Altec lit it does look very JBLish. Guess it is original.

[yggdrasil]

Here's a 411-8A I refoamed 2 years ago. It is original except from the refoam job. Has been in the family since it's birth....

It is refoamed on the outside, like Altec original.

[Earl K]

Nice pic Johnny !

- Do you use this speaker as a sub in one of your setups ?
- If so, how does it stack up against 2235(s) ? ( I actually forget if you have any ) .
- Regarding the cone weight & thickness / does the cone feel thicker than that of a 2235H ?

- ( I don't suppose that you have Woofer Tester do you ? :p )

:)

[yggdrasil]

The 411's are used in this project: http://audioheritage.org/vbulletin/showthread.php?t=4950

They live with a very good friend of mine nowadays. We have been upgrading his electronics lately, to give the speakers adequate matching. The poweramp is now very good, but the preamp and sources are of rather poor quality, so any comparison will be affected by that.

Anyway, I only have LE15's in my Sovereign's (TV-speakers, not good enough for HiFi with the stock crossovers) and 2245's in my DIY's. Compared to the 2245's the sound is "fatter" and less accurate and not in the same league at all.

They are very willing and able in the lower octave's. I actually measured their usable response down to ~25Hz in this setup.

I don't have woofer tester, but I have made an impedance jig for Speaker workshop which works quite well. I'll try to remember it next time I go visit.

The cone weight / thickness - Did not do a comparison. First refoam, lots of nerves...:p

[Earl K]

Thanks for the link John,

I had completely forgotten about your nice DIY project .

Your friend is very lucky !

:)

[moldyoldy]

...snip... Weighing the cone/coil assembly would give us mmd ( which is "mms" minus the air load / which is quite small ).

- Triple the weight of a 515 cone would certainly push the 411-8a into 2235 territory ( maybe more ).
- That would be quite a bit more than the mms spec. that what Grumpy found and posted . Very Interesting .
- FWIW ; I've seen Bill Woods quote TS numbers that seem to come from that web site. I wondered about them at the time since they state the 414-8C as having more BL than a 416-8C / which is quite unusual for woofers from within the same engineered family .



:)

OK, Earl. finally found someone that didn't hang up on me when I asked to borrow a gram scale. My estimate of 3X a 515 was a little much;

411-8A moving assy (complete less surround) - 76.2g.

515-16G moving assy (incl 2/3 of surround) 35.5g.

(Both assys from the EV era, as indicated by the long 18- pt numbers).

Just noticed your quandry on the 414-8C. They deviated a little in series structure there, the 414-8C used the stepped AlNiCo motor of the 416-8B, unlike the switch to ferrite in the 416-8C.

[moldyoldy]

While this 411 died from shifted mag/pole, it apparrently also suffered from the all-to-common (to 411s) spider fatigue.

[Earl K]

Thanks !


OK, Earl. finally found someone that didn't hang up on me when I asked to borrow a gram scale. My estimate of 3X a 515 was a little much;

411-8A moving assy (complete less surround) - 76.2g.

515-16G moving assy (incl 2/3 of surround) 35.5g.

(Both assys from the EV era, as indicated by the long 18- pt numbers).

- Hmmmm, these weights can't be telling the whole story .
- I still expect mms is about twice these weights .

- From what I can see , these weights also wouldn't represent an approx. "MMD" figure / which is "MMS" less the airload .



:)

[moldyoldy]

Y' lost me man. I'm (very) math-challenged, :homer: anything beyond Ohm's or Kirchoff's formulas leave me depending on someone's spreadsheet or program to solve, and even with a solution, I seldom understand how it was arrived.

The unit pictured is as-weighed, and the scale zeroed when I removed it. Did I get bad/useless data, or does it just not fit with published/expected?

[Earl K]

The unit pictured is as-weighed, and the scale zeroed when I removed it. Did I get bad/useless data, or does it just not fit with published/expected?

- Really, I don't know quite how your data fits into the grand scheme of things / but / efficiency is intractably intertwined with cone weight and the BL factor ( and vica versa as GordonW has pointed out ).
- So anectotally, a published sensitivety figure in the low 90s' and the partial BL figure ( in this case, the gap strength ) of 9500 Gauss , strongly suggests a greater mms than that of a le15 ( @ 97 grams ) .

cheers :)

[moldyoldy]

Thanks Earl, got it now, words and pix penetrate my thickness when the algebra just bounces off. :)

(I told my HS algebra teacher nobody cared what x equaled, then blew off a music scholarship for the privelege of paying for votech electronics. Never had trouble getting work, but I've always wondered 'what if'. :banghead: )