question HF driver

[MartinV56]

Hello to all the members of this forum, I acquired old cabins altec, the reference is 870B Speaker System, Serial 892, Number 391916, AL75. The woofer is 420Y biflex woofer with a tweeter on a strap across the front of the woofer. I adds to them EVoice 35T tweeter and XO EV 35 (3500 Hz), and work fine. The cabin is 861B. My amps are Set 2A3 and 45. I not if could add a HF horn driver?, that you think, Any comment advice is very much welcome. Thanks, again, Martin

[Zilch]

I see 861B is the 870B cabinet. What is it? Can you provide a link to the description? What are the dimensions, and is the front baffle removable?

[speakerdave]

. . . . I not if could add a HF horn driver? . . . .

Yes, you could do that, and it might be a good idea. The horn would need to sit on top of the cabinet, of course. You would also need to get the compression drivers, as you note. I would suggest the 811b horn and a pair of whatever Altec driver you can get that will work on it (804, 806, 802, 808, 807) with aluminum diaphragms installed. Finally, you would need a crossover. The 801-8A would work.

You would want to disconnect the coaxial tweeter, maybe even remove it so it is out of the way. I would also set aside the EV T35 and add it back in only if you were not satisfied with the woofer and 811b/compression driver combination as a two-way.

Having done all this you would still have a compromised system because the 420 biflex will not give the same performance as the 416 woofer, and that cabinet is too small to get good bass performance from either one.

If you eventually have the 420 reconed to a 416 you would have the equivalent of the Altec Valencia, if you could find or build the right sized cabinets.

David

[MartinV56]

I see 861B is the 870B cabinet. What is it? Can you provide a link to the description? What are the dimensions, and is the front baffle removable?

Thanks, The number 870B is the Altec speaker system, 861B is the number type cabinet

http://img253.imageshack.us/img253/5304/470bsystem420yxe2.th.jpg (http://img253.imageshack.us/my.php?image=470bsystem420yxe2.jpg)

http://img117.imageshack.us/img117/2742/870bahn3.th.png (http://img117.imageshack.us/my.php?image=870bahn3.png)

http://img170.imageshack.us/img170/9162/x0vercr35tj3.th.jpg (http://img170.imageshack.us/my.php?image=x0vercr35tj3.jpg)

http://img260.imageshack.us/img260/9930/page06os2.th.jpg (http://img260.imageshack.us/my.php?image=page06os2.jpg)

[MartinV56]

Yes, you could do that, and it might be a good idea. The horn would need to sit on top of the cabinet, of course. You would also need to get the compression drivers, as you note. I would suggest the 811b horn and a pair of whatever Altec driver you can get that will work on it (804, 806, 802, 808, 807) with aluminum diaphragms installed. Finally, you would need a crossover. The 801-8A would work.

You would want to disconnect the coaxial tweeter, maybe even remove it so it is out of the way. I would also set aside the EV T35 and add it back in only if you were not satisfied with the woofer and 811b/compression driver combination as a two-way.

Having done all this you would still have a compromised system because the 420 biflex will not give the same performance as the 416 woofer, and that cabinet is too small to get good bass performance from either one.

If you eventually have the 420 reconed to a 416 you would have the equivalent of the Altec Valencia, if you could find or build the right sized cabinets.

David

Thanks David,
I believe that it is a good idea, thanks for your commentaries, will begin to look for drivers and horns with recommended crossover

[Zilch]

Thanks, The number 870B is the Altec speaker system, 861B is the number type cabinet.Yes, but what are the dimensions, including the front baffle, and is it removable?

As you know, I have recently measured 420Y in the apparently similar size 872B Madrid cabinet, and just completed extensive work in other threads with "fixing" the driver/horn complement and "compromised" system you would now pursue.

Provide the dimensions, and I may have an alternative to propose for your consideration....

[MartinV56]

Thanks, dimensions cabinet are in cms

W55 X D45 X H59

Front panel: 48X51X 44

[Zilch]

Thanks, dimensions cabinet are in cms

W55 X D45 X H59

Front panel: 48X51X 44O.K.

Allowing 1.9 cm for wall thickness all around, I calculate the internal volume as 116.4 liters, or just over 4 cuft. Do you confirm?

And the front baffle is 18.89" wide by 20" high?

Most importantly, now, is the front panel removable, that is, could you easily make and install a different baffle with different drivers?

See Jackgiff's Altec Santana conversion here:

http://audioheritage.org/vbulletin/showthread.php?t=17408

LE14 is 12.75" across the face, and the waveguide is 6.5" high, total 19.25".

If my conversions of your dimensions are correct, you have .75" to spare. :yes:

Will that work for you?

[MartinV56]

Thanks Zilch,
Yes is for me, I make for me the Set amps, 2A3, 45 and 300B and need efficient speakers for the 45 amp. My experience or tell storie

From very young been I have pricked by music and its good reproduction. That length and expensive way that is the search of the absolute sound, took to me to prove many marks and classes of amplifiers, solid state, Harman Kardon, Bryston, Krell, Lexicon, Morrison Elad, B&K, PP tubes Scott 299, Heathkit AA-100, equipment that I had and of which I have a good memory by the musical benefit that granted to me. In that permanent and per moments obsessive search, I arrived from the vacuum tube sound that it had in the memory “of there far and for a long time”. Such search took to me to make my valve amps, circuit type class A, Single ended triode with the valves 2A3, 300B and 45. The first amplifier Single Ended Triode DHT, that I did was on the base of the Sun Audio. To command to make the output transformer or to concern them, brands like James, Lundhal, Tango, Magnaquest, Hammond, they happened through my mind. For lightening of the pocket, I was decided by the alternative to send them to make with a local craftsman, began the search of a good iron, oriented grain, M4 laminae, to calculate the Zprimario for the venerable valve 2A3, with preamplification of excellent 6SN7GT, soon the manufacture of the chassis, its electrostatic painting, etc. Purchase of the menaje, condensers, resistance, sockets, rheostats, potentiometers, etc. Once assembled and concerned from the U.S.A. 2A3 and 6SN7GT, the day of the test of the prototype arrived that had done. To listen to an amplifier Single Ended Triode for the first time is a unique and unique experience in my memory. I think in the simplicity of the circuit is the quality of its sound. The SET sounds different who the amplifiers solid state and push-pull by the distortion which they produce well-known like second harmonic distrotion, which is equivalent to add in the tone the one eighth highest one, forming agreed a very pleasant one to the human ear. The Single Ended Triode requires of very sensible loudspeakers, reason that took to leave the Infinity Kappa 7 and Altec Nine to me and to look for those of high efficiency type full range. I buy in a local salesman the altec 870B with woofer 418B and the EV T35 tweeter and crossover in other local salesman . Warm greeting, Martin

My listened room, uyy sorry bad photo

http://img508.imageshack.us/img508/9388/00100py7.th.jpg (http://img508.imageshack.us/my.php?image=00100py7.jpg)

The 2A3 Set amp

http://img295.imageshack.us/img295/453/0004kf8.th.jpg (http://img295.imageshack.us/my.php?image=0004kf8.jpg)

Making the 2A3
http://img374.imageshack.us/img374/1207/0018ig8.th.jpg (http://img374.imageshack.us/my.php?image=0018ig8.jpg)

The 870B 418 speaker with EV 35 tweeter and control crossover

http://img295.imageshack.us/img295/3995/00090bd5.th.jpg (http://img295.imageshack.us/my.php?image=00090bd5.jpg)

[Zilch]

LE14 is not a high-efficiency woofer, so it depends upon how much power you actually have available, and how loud you want it to play, to determine whether it will work for you, then.

If not, then other options are biamping using SS for the woofer, or choosing a more efficient 12" woofer instead. Generally speaking, you must trade off efficiency to get extended bass, or use a supplemental subwoofer.

A major point i'm making here is that you can fit a worthwhile upgrade into your existing cabinets, if you are willing to give up the 15" woofer. As you read elsewhere, I found the 420Y I tested "mediocre," and I believe David has suggested much the same in his post, above.

In any case, based upon my recent work with them, I would certainly use BMS compression drivers rather than any of the vintage Altecs for the high frequencies, whether they are on Altec horns or JBL waveguides, as you ultimately deem may be appropriate for your project....

[MartinV56]

Thanks Zilch

Summarizing the provided information, the project would be: 1) The present woofer 420y biflex 2) Tweeter EV t-35 with crossover EV-35 (3500 Hertz)
Cabinet 870B Speaker System

The project would be

The horn put on top of the cabinet:
BMS 4550 http://www.woodhorn.com/BMS/bms_4550.htm
Wood horn 17" 800Hz
Crossover 800 hz
Thanks again, Martin

[Zilch]

I advise that you forget the T-35. The BMS 4550 will play competently to 20 kHz, provided your horn will support VHF, and it has plenty of headroom to allow the requisite compensation for it to play flat the entire way.

Review the measured T-35 response. I don't believe it can contribute anything but problems to your system; it hardly even qualifies as a tweeter by contemporary standards:

http://audioheritage.org/vbulletin/showthread.php?p=154794&#post154794

[MartinV56]

Hi, guys, Them again annoying with a question, they know whatever can cost the 604 in greatplain, I believe that a good alternative is to replace 420y with the 604 of greatplain, Thanks, Martin

[speakerdave]

Hi, guys, Them again annoying with a question, they know whatever can cost the 604 in greatplain, I believe that a good alternative is to replace 420y with the 604 of greatplain, Thanks, Martin

You could do that, though it will be better to get those cabinets about two feet off the floor, and, again, the bass wll be attenuated by the size of the cabinet.

They (GPA) don't give out their prices on line. Contact information is at this URL. You can phone or email them.

http://www.greatplainsaudio.com/contact.html

David

[MartinV56]

Thanks David, my cabin is 861 it is very simillar 859B and Altec recommends for those following cabins the duplex 604,602,605 and the 601 12".

[speakerdave]

Thanks David, my cabin is 861 it is very simillar 859B and Altec recommends for those following cabins the duplex 604,602,605 and the 601 12".

Looks like clear sailing ahead!

[Zilch]

Unless I'm missing something, 859B is not shown in the PDF.

If you mean 859A, that's 5.7 cuft, and I calculated your cabinet at 4 cuft.

No matter, the PDF also says 604 is suitable for use in other boxes as small as 3.23 cuft.

So, to verify that information, go to GPA and get the T/S parameters for their 604-8H-II which you are considering purchasing, and put them in a box modeling program at 4 cuft volume.

The usable bass (-10 dB) doesn't even reach 40 Hz in your cabinet, and you need 8 cuft to get that driver playing to 30 Hz per the specification.


... the bass wll be attenuated by the size of the cabinet.

Yes, you will need a subwoofer, if my calcs are correct. Bottom graph is box tunings from 28 to 48 Hz, step 5 Hz.

[Do it yourself to be certain, tho.... :yes: ]

[MartinV56]

Thanks Zilch, sorry, 859A very similar with the 861B, in the PDF say some duplex, thanks again, Martín

[MartinV56]

I believe that the best thing is to rectify the measures of the cabin 861B with the people of greatplains or to look for another full range speaker or to leave to the system 870B with 420y, thanks, Martín

[MartinV56]

Hi, view this post

http://www.audioheritage.org/vbulletin/showthread.php?t=502