Altec 811B question

[Tube Radio]

Is there a currently produced compression driver that will fit the 811B horn and give it a fairly flat if not completely flat frequency response from 800-16KHz? I'd be interested in vintage JBL or Altec drivers if four can be sourced relatively easily at a reasonable price, but if not I'll buy new drivers.

If not are there any other easily sourced Altec or JBL horns at a reasonable price that will accept a driver which will do 800-16KHz?

Power rating of the driver should be at least 40 watts.


Working on a sound system for a skating rink which had a nice audio system at one time consisting of Yamaha horns BFI Bullfrog midbass cabinets and JBL 4520 cabinets for the bass and my plan was to restore those to working condition, but when the owner went into foreclosure recently he took the whole sound system and made it necessary for me to redesign the whole system from the ground up.

I'm either going with four speakers like it was set up when the rink closed (had four electrovoice speakers sitting on top of the 4520 speakers) or I'll go to the original configuration of 8 midbass cabinets and 8 horns. All depends on what the new owner can afford and wants to do if a new owner is found.

Another question I have is this.

Is there an Altec or JBL horn loaded enclosure or plans for one that has the 811B or another Altec or JBL horn built in?

If so that would simplify things as I will need to have the midbass cabinets built from plans or buy some if the extra empty BFI bullfrog cabinet is not there for me to have measured and more built just like it.

This all depends on whether or not the original system can be recovered.

[Earl K]

Do a search for "Zilch, BMS 4550" ( here at LHF, &/or Google ).

The BMS driver works quite well on the 811b.



The above trace is with the Altec N-800K network ( hi-pass portion > clearly the 800hz goal isn't achieved ) .

Zilch never ( to my knowledge ) published the raw response of that driver on the 811 ( he always had a network of some sort in place ).
- Therefore it's hard to know if that driver can make it down there.

[Tube Radio]

If it wasn't for the 800Hz response needed from the horn due to the horn loaded midbass cabinets usually being crossed over at 800Hz I'd just use an Eminence PSD2002-8 driver which crossed over at 1.7KHz is flat to 16KHz on the 811B horn. Have that setup in my home stereo and it does sound good.


Will take a look at the driver you mentioned and see how suitable it is.


I am going to use the new Yamaha 500 WPC into 4 ohms amps that have built in DSP. That way I don't need any external crossovers and eq as it's built in and also has built in limiters so I can set it to where no amount of abuse will damage the drivers plus I can set one amp up and transfer the settings to the other amps using as thumb drive along with locking the front panel with a code so no one can change the settings.

[Earl K]

You're going to find that the older legacy drivers had a bit more low-mid to mid response ( at the expense of HF response ) than the newer generation of compression drivers.

You'll need to carefully pick your poison ( 800 hz point vs usable response above @15K ).

I'd wager that some used JBL 2426's ( fitted with a JBL 2421 aluminum diaphragm ) screwed into this very inexpensive bi-radial horn , would fit the bill ( for the 800hz crossover point ).




All of these solutions will need some HF compensation ( ie; a 6 to 9db suppression of the mids from 1K to 4K ) to get anywhere close to flat .



PS#1 - Just realized this is meant for that skating rink install you've been talking about / therefore, forget the aluminum diaphragm that I just mentioned and use the stock (JBL) titanium diaphragm ( it's a lot more rugged ) .

PS#2 - If you purchase those horns to test out, you'll find the plastic is pretty light-weight ( ie; it could use some extra damping put over it ( ie; some sticky "auto-supply" damping, Quiet-Kote type material or whatever works for you in that department ) .

[Tube Radio]

Is it possible to modify a horn loaded midbass enclosure to where it can be used up to 1.2KHz?

If so that would simplify things as I could just use that Eminence driver I mentioned.

Concerning the BMS compression driver given the amps I'm going to use have a built in eq it would be possible to eq the driver to where it sounds its best.

The power rating of that driver is very good as well.

Earl, would that horn work well with the BMS driver listed here?

Just saw what you posted and maybe that horn might not be good for me to use then.

The problem is I don't know how much whoever buys the rink can spend on the sound system.

[Earl K]

Is it possible to modify a horn loaded midbass enclosure to where it can be used up to 1.2KHz?

I doubt it !

If so that would simplify things as I could just use that Eminence driver I mentioned.

Concerning the BMS compression driver given the amps I'm going to use have a built in eq it would be possible to eq the driver to where it sounds its best.

Yes, that's one way to go > personally, a bit of builtin mid-band suppression with a capacitor bypass to restore the HF, sounds better .

The power rating of that driver is very good as well.

Earl, would that horn work well with the BMS driver listed here?

Only if there's a screw-on version of that driver ( which I don't know off-hand if one is available ) .

BTW, that bull-frog mid-horn box looks like a rip-o-matic of the Altec 816 box.

This site has plans for that box.






You really need to sharpen your Google skills ( as well as become more familiar with all the resources found at this site ).

[Mr. Widget]

BTW, that bull-frog mid-horn box looks like a rip-o-matic of the Altec 816 box.

Where does one go to buy factory authorized rip-o-matic products?


Widget

[Tube Radio]

Agreed I do need to sharpen my skills, but since I'm not very familiar with horn loaded enclosures I prefer to ask those who do know about those enclosures so that I get it right the first time.

If the owner does want to have cabinets built I will also have a part built on to the midbass cabinets to mount the high frequency horns in.

[Earl K]

Where does one go to buy factory authorized rip-o-matic products?


Widget

Now don't get too technical.

My intent is display the provenance of the 816.




PS; All due to the ( in-inadvertent ) "Bull-Frog" mis-education ( & attendant, mis-direction ) .

[Tube Radio]

I'll start a separate topic about the midbass horns.

[Tube Radio]

Concerning the 811B horns with that BMS driver, what circuit would be recommended for compensation or would it be better to do it with the built in eq settings of the Yamaha amps I'm going to use?

Also what about the BMS 4552ND compression drivers?

http://www.bmsspeakers.com/index.php?id=bms_4552nd

Would they be a better choice?

Is there any other Altec or JBL horn that is fairly easy to source for not a lot of money?

EDIT: now would it be possible to get some of those Jbl 2360 horns that were commonly used in theatres and are easily found now and either suspend them from the ceiling between the speaker stacks perhaps only needing two of them or suspending them above the speaker stacks? If so what driver would be best for them provided there is a driver that can reach 16KHz on that horn.