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beto
07-11-2005, 11:33 AM
Hello,
Can someone povide me some information about Altec A7 (or A7-500) components combination to match with an SET 300B tube amp with just 8 watts power? One of the good thing, as you know , about this kind of amps was the astonishing middle range and its sweet sound with acoustic instruments. I hear a lot of dfferent music: acoustic jazz, classic, folk, world, rock, etc. son aldo up and down frequencyies are also a matter.
One matter that I have read is regarding magnetism loss on the old alnico magnets, so in my pre selection I will put the last one on HF: 802G and for LF 416 B . This is because I also have read about magic alnico-set combo, but being honestly, I don't know nothing about it, because I have never heard and alnico magnet with my SET amp. For this reazon also my second preselection was 902A ferrite magnet and 416C or 515-18G combo. About sectoral difusor I'm in doubt because I do'nt know which one, 511B or 811B match best in a house use. Obviously same thing with the crossover: 500 or 800HZ? . My living room has 3.47 meters X 5meters, but I only can put the audio equipment on the large side, so 3.47 meter is the distance to load. For LF horn, I supose that 828 is the one, this is not problem for me. I'm an architect with some skill and I can build this cabinets by myself.
Thank you very much in advance,
AD

speakerdave
07-11-2005, 12:13 PM
Hi, Beto.

Welcome to the forum. Although there are many people who have put together systems like the one you propose, personally, in that room, listening at that distance, driven with those amps, I would suggest, if you want an Altec system, that you consider the 604 coaxial.

There may be others here who have some suggestions, but you also may find people of like interest on the forum at Great Plains Audio, which is an outfit working to keep the classic Altec flame burning.

We have some plans for building Altec cabinets. You can find them using the Library link above and choosing the Altec Library. (Although I have to tell you I just now was not able to open some of them.)

David

beto
07-11-2005, 12:46 PM
Thank you David for your advises.
I have visited the Altec Library and I have download all the concerning information last year, but now I'm clasifying it.
My major doubt is about alnico longetivity, ferrite feasibility and SET sound. I have read a Sound Practices article about this concerns but the focus is on modern theater system, maybe with solid state amps, not for Hi Fi or tube sound.
I have heard, a year or so ago, an Altec A7 with a push pull tube amp in an slightly big living room and its sound great, but the equipment was on the small side of the rectangle, so it has 5 meters in front.
By the way, only in sound reproduction matching a 300B SET amp, do think that ferrite magnet will do the same work than alnico?
Regarding consider another Altec system: I'm absolutely open to change my mind to get the best sound form my beatiful sounding SET amp.
Regards,
beto

speakerdave
07-11-2005, 01:38 PM
My major doubt is about alnico longetivity, ferrite feasibility and SET sound.

Alnico longevity: In buying used Alnico drivers there is always the possibility that they have lost some magnetism from a variety of causes, but they can be remagnetized. Once you have had that done, there is no possibility they will ever need it again if they a driven with 300B amps, unless they are somehow overheated or dropped.

Ferrite feasibility: Personally I would choose Alnico among the Altec drivers, but if you want the tangerine phase plug in the compression driver, the ferrite 902 is probably the easiest way to get it.

SET sound: Not sure what your question is here. I am personally not familiar with SET amps. I do have an appreciation for very refined audio reproduction at modest volume, but I also like efficient speakers driven by fairly large amps, and on balance prefer that because it is the only way to take full advantage of the dynamism of a large efficient speaker.



By the way, only in sound reproduction matching a 300B SET amp, do think that ferrite magnet will do the same work than alnico?

I don't know. There are probably a lot of other things in the reproduction chain that make more difference. Both materials have their shortcomings. JBL was able to engineer out the known ones in the ferrite systems, but I am not aware of such work being done at Altec. Some Altec aficionados seem to not be bothered by ferrite. I have listened to only Alnico Altec and have liked it. This you would have to decide for yourself.



Regarding consider another Altec system: I'm absolutely open to change my mind to get the best sound form my beatiful sounding SET amp.
I was only thinking of how close you would be to the speakers. Based on what I have read, apparently there have been users of SET amps who have been happy with either the 604 or the separate woofer and horn systems.

David

beto
07-11-2005, 02:04 PM
Thank you David, again.

I have to check, here in my country if some one can remagnetize Altec alnico magnets if I will need it.
Some guy here, offer me a pair of 601 8d duplex with 501-8a crossovers. As I know 604 was the 601 upgrade, in a close to a Valencia cabinet, maybe I will deal with he to get a listening test with my amp.
Well, I'm new on this, so I have to be pacient to find the best match.
Regards,
beto

speakerdave
07-11-2005, 02:10 PM
I think in your country Great Plains Audio and Orange County Speakers would be the best bets.

David

Mr. Widget
07-11-2005, 11:39 PM
Hello,
Can someone povide me some information about Altec A7 (or A7-500) components combination to match with an SET 300B....

Have you heard an A-7 at a friend's or at a dealer's? If you are looking at any speaker based on reading about them I would suggest a train ride or airfare before making such a commitment. Speakers have even more "personality" than amplifiers.

There are so many other potential dangers to buying used speakers... over the magnet type. Many of these vintage speakers were used outdoors, or abused in PA systems, or have been dropped...

I have made many good purchases over the years, but unfortunately about a third of the used gear I have bought really wasn't quite up to spec. To remedy this I had to spend some money rebuilding them.

Good Luck!

Widget

tomp787
07-12-2005, 02:12 AM
Hello,

Here is another Altec cabinet to consider. I think it will fit into a home better than the A5/A7 series and the dual woofer will increase efficency to better suit your low power amp.

http://www.highefficiencyloudspeakers.com/user/80Hz_Horn-2X15-1.jpg

http://www.highefficiencyloudspeakers.com/user/80Hz_Horn-2X15-2.jpg

http://www.highefficiencyloudspeakers.com/user/80Hz_Horn-2X15-3.jpg

Another option would be the Jensen Imperial cabinet. It is a rear loaded horn which again improves efficency to suit your SET amp. The Imperial cabinet could also be used with a coaxial driver like 604, etc

http://www.highefficiencyloudspeakers.com/user/Imperial_Floor-standing.jpg

http://www.highefficiencyloudspeakers.com/user/Imperial_Build-in.jpg

I have used an earlier version of the "build in" cabinet with Altec 605 and I liked it. It is very large. Since you are an architect you could build it into the wall to maximize its performance and control its visual impact. If you decide on the imperial built in I can find the earlier article that describes it.

Regards,
Tom

beto
07-12-2005, 11:42 AM
Have you heard an A-7 at a friend's or at a dealer's? If you are looking at any speaker based on reading about them I would suggest a train ride or airfare before making such a commitment. Speakers have even more "personality" than amplifiers.
Widget
Hi Mr. Widget,
I have heard a beautiful sounding Altec A7 and 19 model at a friend house who own both. He has also a few tubes amplifiers an we test both speakers with digital and analog sources.
To be very honest I think, maybe, I will want a little more very deep bass, but all other frequencies sounds wonderful and detailed. I supose if I have to make a decision between deep bass and good mid frequencies I prefer mid frequencies. We do the test with classical music (my friend was a violinist)acoustic jazz and also pop. I remember that sounds was too fluid with complex passages and I was very impress. Most of the test was performed on the A7 pair (517B LF, 902-8 HF and 800 Hz crossover) and with a KT88 push pull amp and a little with a 3.5 watts 2A3 SET.
Now I'm on my own trying to find some components and trying to resolve the best equation to match my amp and my place.
Thanks a lot for your comments.
Beto

beto
07-12-2005, 11:55 AM
Another option would be the Jensen Imperial cabinet. It is a rear loaded horn which again improves efficency to suit your SET amp. The Imperial cabinet could also be used with a coaxial driver like 604, etc

Hi Tom,
thank you very much for your information. To be honest, I have never heard about this cabinets. I'm a newbie on vintage high efficience speakers. I will like to read some reviews about this cabinet/speaker combo.
Now I'm absolutely open to change from my A7 proyect to other to fits better with my 3.5 x 5 meters living room.



I have used an earlier version of the "build in" cabinet with Altec 605 and I liked it. It is very large. Since you are an architect you could build it into the wall to maximize its performance and control its visual impact.

We share this idea, but I don't have a dedicated room for audio yet, so just hear music on my living room.
Regards,
Beto

Tom Brennan
07-12-2005, 12:02 PM
Beto---In my opinion the ferrite Altec compression drivers sound every bit as good as the Alnico ones. Were I looking for a pair of drivers I'd look for 902s.

As for ferrite vs Alnico in Altec woofers I don't know, I never owned any ferrite ones.

I prefer the 416 in the 825-828 cabinet to the 515; it makes better bass. However if using a sub I'd go with 515s because I think they do the midrange a little better than 416s. My last VOT rig used 515Bs in 825s (A5) augmented below 100hz by a pair of JBL 4648 bassbins. But without the 4 JBL 15s at work the A5s sounded bass-shy to me.

What horn to use is a matter of preference and the nature of the room. I've used many horns on Altec drivers and when all was said and done I think the best were the old 511, 811 and the Edgar round wood "saladbowl" tractrix horns.

Mr. Widget
07-12-2005, 01:34 PM
I have heard a beautiful sounding Altec A7 and 19 model at a friend house who own both.
Well then you know how they sound and how large they need to be... we certainly have the plans here for you. Next you need to track down the drivers.

I would agree with Tom about the ferrite HF drivers... I like alnico woofers, but that maybe more sentimental than based on performance.

Good luck finding clean drivers, keep us posted with your progress!

Widget

beto
07-13-2005, 08:54 AM
Hi Tom and Mr. Widget,

thanks for your advises. Yes I know that maybe it's a setimental matter about alnico magnets, but there are some people that cosider alnico the best. If I can't get a good pair, I don't know if here, in my country, Chile I can obtain an specialized Altec remagnetized service, so I must find the latest alnico production for safety like 802G and 416B I think to avoid huge shipping cost. But putting sentimentalism away, I prefer to resolve the best way to obtain deep bass in a 825/828 cabinet with my limited "throw".
On other Altec forum an expert advise about to put a pair of 515's to obatain both, hi quality mid fq and deep well managed bass, working best in my 3.5 meters, but the ugly side is the cost.
Well gentlemen, the alnico/ferrite/enclosure/500/800hz/short throw battle have began.
Regards

beto
07-15-2005, 04:03 PM
Although there are many people who have put together systems like the one you propose, personally, in that room, listening at that distance, driven with those amps, I would suggest, if you want an Altec system, that you consider the 604 coaxial.

Hi David, I'm also considering a 604 Duplex system. Can you advise me about wich cabinet? Maybe 604-8G/620A? It's goes down to 20Hz with 100dB efficience on the paper. Do you think that deep around 20Hz can be possible on my 3.5 meters short throw?
Thanks in advance.
Beto

speakerdave
07-15-2005, 04:31 PM
You are talking about frequencies which are below cabinet tuning and well into the region where the room is part of the dynamic. The short answer is probably, "No, you will not have well-controlled 20 Hz from that speaker (in any enclosure)" Iconic makes an enclosure with the same volume tuned to 30 Hz; Altec (and billfort) have theirs tuned to 40 Hz, probably for smoother response (a less severe dropoff below cutoff). If you try to push your woofer below the bass reflex cabinet tuning frequency you can drive the cone into excessive excursion, not something you will want to do with a fine collectable like the 604. Also there are differences in the 604's of different eras. The older ones have stiff paper surrounds like the 515B (same cone I think). The later ones have the accordian surrounds and are spec'ed at 25 Hz FAR. I think your best bet for overall response is the 40 Hz tuning, but 30 Hz might be worth trying, if you want to reach for low bass. All that having been said, you will have some VLF response in your room due to what is called room rise--the dimensions of the room and its air volume will resonate certain frequencies. So, if you play organ music with low pedal notes you will probably get some sound, but it may be peaky (probably still would be fun).

I did see on the other forum that billfort seconded my suggestion to consider the 604. He is very happy with his speakers, I believe. If you want very low bass with this driver you will need a subwoofer (as you would with the A7 or Model 19). I have suggested in the past the JBL 2242. Maybe our techbot will weigh in with specific cabinet recommendations for that. That is a high performance, high efficiency 18" woofer which is good from the low 20's up to the low hundreds. If you use that you could use the 604 in a smaller closed enclosure crossed over at 80 Hz, and I believe, have better transient response up into the mids

David.

scott fitlin
07-15-2005, 04:36 PM
Use the Altecs within the ranges their truly good at! Excessive VLF will only strain the high compliance suspensions, and not really deliver truly clean deep bass information!

I would opt to tune the 604,s to 40hz or try the 30,s as suggested, and get a really good subwoofer to deliver the VLF properly!

beto
07-15-2005, 05:53 PM
David and Scott,

thanks for your posts. Yes, I think 40 Hz will be Ok. for 90% or more, of my music, but 30Hz will be a dream comes true with a Hi Eff. speaker.
I have take the Fq response for the 604/620 combo on the unnoficial site brochure, so that's why I have say "on the paper".
As a general concept , I prefer a sweet mid range sounding system, with a good and controled bass, down to its limits, but clear, articulated, etc. Prefer less, but a very good quality.
Sugestions on enclosures tunned for 40hz?
Regards,
Beto

tomp787
07-17-2005, 11:42 PM
Hello,

The 604 can be used in many different enclosures that can be found on the internet. Remember to include your amplifier output impedance when you calculate the tuning frequency. Most speaker software assumes zero source impedance from the amplifier while your amp may have 2 or more ohms source impedance. You can recalculate Qes using the true amplifier output resistance then have the software help with your box tuning.

Regarding the boxes the Altec 620 is good as is Billfort's corner version. Altec also made a corner box called the 606, I believe. Various vintage designs will also work for the 604 like the Jensen Imperial horn and the Karlson K15.

I suggest you build one of each and tell us which you prefer! I am most interested in the corner Imperial and the Karlson K15. I can send you plans if you can't find them on the www.

Regards,
Tom

ngccglp
07-18-2005, 07:06 AM
Hi Beto,

I am using the A7-500 (802-8D, 416-8B, JBL 2405) with the Unison Research S2K (15 watts) in a 3.5 m x 3.5 m room !! Believe me, its more than enough power for the A7.
In room this size, you will not be able to realize the full potential of the speakers in terms of the size of the sound stage it is capable of.

But I'm used to near field listening and enjoy the A7 for its transparency and nice bass extension. The speakers does a very good disappearing act.

beto
07-18-2005, 07:24 PM
In room this size, you will not be able to realize the full potential of the speakers in terms of the size of the sound stage it is capable of.

Thanks ngccglp for sharing your experience. It's seem that the right thing for my in this moments is to get a pair of 604's drivers, but, the A7 system also is on my thoughs because is the one I have experienced and also love it. Now I'm seeking for componets in my country so this add a little hazard because the availability.
Maybe in the future I can change my equipment to the short side of the rectangle and the A7 will be match better on 5 meter throw.
Regards,
Beto

beto
07-19-2005, 04:41 PM
I suggest you build one of each and tell us which you prefer! I am most interested in the corner Imperial and the Karlson K15. I can send you plans if you can't find them on the www.

Thank you Tom for you offer and comments. Now I'm searching for the drivers in my country, so meanwhile I will study wich cabinet will be the best match for my room size/amp output. Accept any suggestion. I don't think that the corner design was for me at this time, since I have placed them on the large side of the rectangle, so corners are far.
Regards,
Beto