a7 componets in Barcelona Box

[Joe S]

Hi guys, I'm brand new to the forum so bear with me, thanks.

I'm a long time affectionado of the Altecs. When I was 18 I purchased 416-8B, 511A Horns and 802D drivers from memeory with hi-fi coils as I recall. I hope I got these numbers right but anyway its the 500 HZ system. sUsed threm for DJ work and they were awesome. Sold my handmade a7 box many years ago as the wife said to big and I miss them dearly.

20 yeras ago I placed my componets LF and driver/horns as above into another handmade barcelona look alikes. The crossover have varied over the years but I'm currently using some JBL 3115 passive crossover. Box looks great but I was never quite happy with the sound. It always seemed to need a lot of equalisation basically needing the centre frequencies pulled out to sound fairly good - you couldn't run them on flat. I did bass reflex port the barcelona box with 4inch pipe about 6 inches long. Twin tubes either side of the panel where the 511 horn mounts. The ports therefore are really not on the same plane as the woofer but I could think of anywhwere else to put. I know the barcelona had a shelving network for the standard 411 woofer but could never find the design for this and in any case didn't think it would be appropriate. Short of rebuilding an a7 does nayone have any ideas on how I could smooth the response on my setup or if it will ever work well in this configuration. Its not that bad nind you and seems to extend down low fairly well in the roughly 5 cubic foot box of the barcelona as I calced it at the time.

Any ideas welcome. BTW I have used the speakers all my life - had to do a geniuine recone of one 416B which seemed to work fine. Also the 502 drivers. What do you think about bi-amping the setup.

I am using a Rotel 1080 seperate main amp (about 250 RMS) and have a matching Rotel seperate main amp about 60 watts for the nhporns I could use.

Cheers and thanks for any opinions.

[speakerdave]

Since no one with deep Altec experience is jumping in here, I'm going to--I can kick the can at least.

The JBL crossover is probably not a good match. I think you should be using an Altec crossover, chosen to go with the impedance of your drivers. Later is better. The options would be the 501, 801 or 1201, the first digit indicating frequency. The latter is the crossover for the Model 19. There is also a crossover which allows you to choose the frequency, 1285, I think, but I seem to recall someone pointng out it is an SR crossover, and lacks the refinement you want for home hi fi. You know, like the JBL 3115.

Quite a bit of talk has gone on here about the Valencia, which uses the 811; that might be appropriate if you are interested in that frequency.

Try your question at the forums in the Great Plains Audio website. They are the inheritors of the Altec mantel. The denizens over there include a fairly dense sprinkling of knowledgable old Altec engineers, contractors, collectors and devotees, with an occasional irrascible newcomer.

David

[Joe S]

Thanks Dave for your assistance - that was a good pickup by you on the impedance problem of the crossover - I looked up the crossover specs on internet and its states 8-16 ohm on bass and 16 ohm on horn - how they can claim 8-16 ohm range on bass and have a set cutover frequency I'm not sure. The horn as you implied would then crossover at the wrong frequency disturbing the overall response.

I may try to bi-amp as I was not that impressed with the componentry especially in early altec crossovers, I opened up, which as I recall used ferrite/iron core coils and bi-polar electrolytics which I though were not meant to be a good idea .

Maybe the Altec 501 crossover you speak of are better but have not been able to see any web reference/specs on this - haven't finished searching yet.

Cheers at thanks again for the hint.

[Zilch]

Biamp and push the CD Horn compensation button on the crossover. Behringer CX3400 is an economical choice, and it also has delay to time-align the drivers.

Alternatively (or also,) upgrade to an Altec driver with tangerine phase plug like 802-8G or 902 and mate with Model 19 crossovers to do the requisite compensation.

Forget 500 Hz. 511 is an 800 Hz minimum horn. If you want to spend the rest of your life dorking with N801 + 30923 compensation, that's an option, as well.

I'm not yet to the point of saying to dump Altec compression drivers altogether in favor of alternatives, but it's getting close....

[Joe S]

Hi Zilch , thanks

2 questions -
1. I guess what you are saying is despite altec advertising the 511 horn as a 500 HZ horn that you reckon in your opinion they cannot really achieve below 800 successfully - have I got this right - I'm hoping I got these numbers right ie that 511 is suppossed to be 500Hz and 811 is supposed to be 800HZ

2. I looked at the Behringer and looks good and the price is good. I had tried a shitty active crossover once from Inkel but when I tried to run in 2 way mode it could not crossover under 1200 HZ. In other words if you set low to cut at 500 that was fine but when you set mid/high the minimum was 1200 HZ so you ended up with a hole in response between 500 and 1200Hz - not a good outcome. I guess they never though someone would want to cross over 2 way at 500Hz. In 3 way mode you could do it ie 0-500hz, 500hz to say 4k, then 4k to max but this of course didn't help. I guess the Behringer doesn't have such a problem in 2 way mode - it's difficult to tell from the spec sheet on-line. I also suppose your suggesting that i crossover at say 800Hz minimum.

3. The horn compensation button sounds good but, excuse my ignorance, how does Behringer know how each manufacturers horn will respond and what amount and type of compensation that horn would need. Is it tuneable or a re certain peaks and troughs in horns just a given. If so, its little wonder I could never makie this sound good without loads of equalisation.

Cheers and thanks again

[Zilch]

JBL used to use the HL91 at 500 Hz. Later, it was an 800 Hz horn. More recently, it's a 1200 Hz horn. Standards evolve based upon knowledge and experience. There's still plenty of users who will attest as to how wonderful HL91 sounds at 500 Hz.

If you're doing two-way with a bass horn that is barely useable at 500 Hz, then you run 511 at 500 Hz and pretend it's good. If you have other options, the limitations become more apparent. Dial the Behringer down to 500 Hz and make your own empirical determination. I'm not making this up, and I am not alone in this assessment.

In detail, there is an optimum HF compensation contour specific to each and every horn/driver combination, and thus there is no generic "standard" curve. However, the response characteristics of common audio compression drivers of similar design are similar, and each crossover and amp manufacturer incorporating a compensation option attempts to approximate a generally applicable curve according to their target market. JBL offered multiple choices in their crossover products.

So, when you push the "CD Horn" button on a Behringer crossover, is it "right" for all combinations? No, but it's a damn sight better than doing nothing, in most cases (A7 springs immediately to mind,) and you still have the option of doing a custom contour passively independent of the crossover function.

http://audioheritage.org/vbulletin/showthread.php?t=4410

[Chas]

After spending lots of time with 511B's and it's little brother the 811B, I would concur with Zilch re. his suggestion regarding the crossover frequency. For 511B's IMHO, 800 Hz would be rock bottom, I used mine set at 1200 Hz second order, most of the time in the end.

Like he suggests, give it a whirl and see what yours ears think.

[Joe S]

Sorry Chas and Zilch - I hadn't vresponded as was away on the weekend . I'm keenly pursuing the active crossover idea (probably the Behringer) and am going to play with this + usual equalisation.

Its probably gpoing to be a few weeks before I get set-up. I knew various Hi_FI home speakers manufacturers had custom designed the contour of their crossovers but for years I never even thought this was done in JBL and Altec crossovers - I thought they were just straight 12db/octave flat contour crossovers. - I just used an equalizer all this time and it looks like the ears will have to be the judge as from what you are both saying even the standard crossovers built were either not built for the driver/cabinet combination I have, ie A7 components in barcelona box, or not of a suitable crossover frequency in real life practice.

Anyway you learn something everyday - pitty took me 30 years to realise - boy- how daft!!!

[Zilch]

I knew various Hi_FI home speakers manufacturers had custom designed the contour of their crossovers but for years I never even thought this was done in JBL and Altec crossovers - I thought they were just straight 12db/octave flat contour crossovers. You would be hard pressed to find a textbook crossover in a JBL system, and when Altec migrated their "Theater" systems into the home, they recognized this application required a different approach. Ultimately, they achieved a workable solution in Model 19 technology....

[Tom Brennan]

The 511 horn works fine at 500hz, in fact it even works fine with 802-806 drivers crossed at 500 hz first order. I have measured it working well that way and more importantly heard it working well that way.

[Russellc]

The 511 horn works fine at 500hz, in fact it even works fine with 802-806 drivers crossed at 500 hz first order. I have measured it working well that way and more importantly heard it working well that way.
Similarly, I have used mine at 500 hz for years and they also work well. While I have recently gone up to 800 hz, part of my success is in the 511B that I have. Not all 511Bs are equal! Older models are welded on all seams and have a little cross support way back in the throat. I have a somewhat newer model that some of the seams are not welded and have what looks like a weld, but is actually a rubber like material. Many have imitated this by taking a sawsall to the 511B, filling the voids with a rubbery material. Also, mine do not have the small cross support back in the throat. This could be removed in the later models as well.

Anyway, with these particular horns, I have had no trouble at 500 hz and certainly prefer it to a 1200 hz crossover in THIS particular application.

Anyone else noticed that there are at least two versions of the 511B?
I have never noticed this with 811B, all I have had are welded on all seams. I say welded, but I dont know how they do it, but it looks like a weld anyway.

Russellc

[Russellc]

JBL used to use the HL91 at 500 Hz. Later, it was an 800 Hz horn. More recently, it's a 1200 Hz horn. Standards evolve based upon knowledge and experience. There's still plenty of users who will attest as to how wonderful HL91 sounds at 500 Hz.

If you're doing two-way with a bass horn that is barely useable at 500 Hz, then you run 511 at 500 Hz and pretend it's good. If you have other options, the limitations become more apparent. Dial the Behringer down to 500 Hz and make your own empirical determination. I'm not making this up, and I am not alone in this assessment.

In detail, there is an optimum HF compensation contour specific to each and every horn/driver combination, and thus there is no generic "standard" curve. However, the response characteristics of common audio compression drivers of similar design are similar, and each crossover and amp manufacturer incorporating a compensation option attempts to approximate a generally applicable curve according to their target market. JBL offered multiple choices in their crossover products.

So, when you push the "CD Horn" button on a Behringer crossover, is it "right" for all combinations? No, but it's a damn sight better than doing nothing, in most cases (A7 springs immediately to mind,) and you still have the option of doing a custom contour passively independent of the crossover function.

http://audioheritage.org/vbulletin/showthread.php?t=4410
zilch, see my post #11, there is more than one version of the 511B.

Cheers,
Russellc

[Joe S]

zilch, see my post #11, there is more than one version of the 511B.

Cheers,
Russellc

Rusell, my 511B are circa 1974 and seem to be fully welded with the crossbrace you speak about near the back of the flare about 4 inches forward of the throat opening. I have seen people modify the horn by stcing "plasticine" , don't know what they call this in the states, but its a kids goey rubber toy substance that sticks to most things like gum but in great wads. They stich this all over the front horn flares in front of the mounting flange on the outside of the horn. This appears to stop the horn ringing in action. Certainly if you flick the horn with your finger it doesn't ring with this arrangement. Is that the sticky subsatnce you are referring to.

This plasticine used to come in half each cylindrical cones about 3 inches long and used for modelling by kids (or adults) I guess.

I haven't tried this on mine but probly just bracing the horn with some rubber pieces pushed between the flare outer and an outer tiber frame (where they are in a box like the Barcelona) would do the trick as well.

What do you reckon, list members.

[Zilch]

I reckon that solidly mounted to a baffle they don't ring nearly as bad as many suppose.

I also reckon that given enough SPL, I can still make them ring.

I further reckon that with music at normal listening levels, I don't hear it.... :dont-know