Large main speakers

[Lee Batchelor]

Good one TLS!

Yes, I should qualify my speaker design a little better. Long ago, I built authentic A7-800 cabinets for my house and other venues. I was obviously young and foolish to carry such heavy units around, but I survived. From the above description you can see I have the 416-8A LF drivers, x-over at 800 Hz, and the 811B horn. I moved from the A-7 cabinets to a re-rigged version of the A7-800 design known as the Valencia; I'm sure most of you know that design. And you're right about messing about with the design. That's when I came up with the idea of using the F3 cut-off at 70 Hz, and a dedicated sub.

I'm not even sure what the F3 was of the A7 or Valencia, beyond Altec's claim. I don't believe it would do much below 45Hz???

I am quite happy with my system as is, but I was curious to see if there was anything I could do to improve it. Seems not.

- Lee

 

[njedpx3]

I've always set my large main speakers to LARGE because they are FULL-RANGE speakers.

If your speakers can truly go below 30 Hz flat, I see no reason why you can't set them to large.

OP, AcuDefTechGuy has Defintive Technology speakers with built-in powered subwoofers, Many fronts are not full-range like the Definitive Technology speakers. Even the higher end DefTech center speakers have a powered sub-woofer.

I have Def tech speakers Fronts 7002 and C/L/R 3000 and the provide a nice range. But I also have an SVS PB12 Plus

Not all fronts are full-range and only a few have built-in powered subwoofers for the really low notes.

Peace and Good Sound,

Forest Man

 

[TLS Guy]

Good one TLS!

Yes, I should qualify my speaker design a little better. Long ago, I built authentic A7-800 cabinets for my house and other venues. I was obviously young and foolish to carry such heavy units around, but I survived. From the above description you can see I have the 416-8A LF drivers, x-over at 800 Hz, and the 811B horn. I moved from the A-7 cabinets to a re-rigged version of the A7-800 design known as the Valencia; I'm sure most of you know that design. And you're right about messing about with the design. That's when I came up with the idea of using the F3 cut-off at 70 Hz, and a dedicated sub.

I'm not even sure what the F3 was of the A7 or Valencia, beyond Altec's claim. I don't believe it would do much below 45Hz???

I am quite happy with my system as is, but I was curious to see if there was anything I could do to improve it. Seems not.

- Lee

The 416-8A is the oldest production of that series with the B and C versions coming later.

The Fs of your driver is 25 Hz. These are rare enough there is no published data for the T/S parameters even on the Great Plains Audio site. So you should get a woofer tester from parts express and publish them.

Having an F3 of 70 Hz with those drivers is a severe misalignment. With proper horn loading they would go well down to the 20 Hz range.

The A7 is a front loaded horn and back loaded reflex, crossover over to a cellular horn at 800 Hz.

The Valencia was an unsuccessful design and short lived.

Now when using these drivers the first thing you do is get rid of the terrible passive crossover. These Altec driver need electronic crossovers and biamping. The Shure SR 106 was basically designed for these speakers.

What HF horn do you have If the compression drivers do not have the Alnico magnets, then the magnets need refluxing by now. Great Plains Audio can do that for you.

Those drivers absolutely need the front loaded horn to sound right. You will not compensate for the thin sound with any sub.

If you really want to get the best out of them you need a huge front and back loaded horn. Next best is to rebuild your A7 cabinets.

What you have now is not a Voice of the Theater system by any criteria, it is well short of the mark.

 

[Lee Batchelor]

Hi again TLS and Forest Man,

Agreed, the Altec LF drivers of the day were meant to be horn loaded. I did have the HF drivers re-built by Great Plains Audio. It made a huge difference! I have recently noticed that one of my LF drivers has a rub in the voice coil and both spiders seem a little sloppy. No wonder, I bought them new in 1974! I really should send them to GPA and have them done. I believe they quoted me about $500-$600. I have also thought of replacing the LF drivers with Eminence or something close. I spoke with an engineer from Eminence and he said the closest model they carry that would work with my horns is the 15" Kappa-Pro. It would cost about the same and I could go with the smaller boxes. Hmmm? The room I'm feeding is 22' x 34' but the sitting area is about 22' x 14'. (I sit about 16' back from the speakers.)

Interesting thought about bi-amping the mains. I've heard this was very successful in the day, especially with the larger 515 systems.

So I guess your saying that if I restored my Altecs back to factory specs, in A7 cabinets, I could set my mains to large?

- Lee

 

[AcuDefTechGuy]

He did love the Orion bass, and the Q on that should be .500 or lower.

True.

The Orion's bass is tight and powerful. It does not have a built-in subwoofer, but the bass is fantastic.

There is no question about "adequate" bass on the Orions.

When your speakers are true "full-range" (for your room size), the bass will be amazingly tight, deep, with good volume.

Specs may say one thing. But when the speakers cannot produce great deep bass, it's pretty obvious to tell, whatever the reason may be - enough power amp, etc.

 

[Pyrrho]

Hi again TLS and Forest Man,

Agreed, the Altec LF drivers of the day were meant to be horn loaded. I did have the HF drivers re-built by Great Plains Audio. It made a huge difference! I have recently noticed that one of my LF drivers has a rub in the voice coil and both spiders seem a little sloppy. No wonder, I bought them new in 1974! I really should send them to GPA and have them done. I believe they quoted me about $500-$600. I have also thought of replacing the LF drivers with Eminence or something close. I spoke with an engineer from Eminence and he said the closest model they carry that would work with my horns is the 15" Kappa-Pro. It would cost about the same and I could go with the smaller boxes. Hmmm? The room I'm feeding is 22' x 34' but the sitting area is about 22' x 14'. (I sit about 16' back from the speakers.)

Interesting thought about bi-amping the mains. I've heard this was very successful in the day, especially with the larger 515 systems.

So I guess your saying that if I restored my Altecs back to factory specs, in A7 cabinets, I could set my mains to large?

- Lee

Unless there is more than one A7 with significantly different properties, with the A7, the -3dB point is at 54Hz, and it is -10dB at 45Hz. See:

http://www.alteclansing.com/content/ebiz/alteclansing/resources/images/usermanual/a7_MAN.pdf

In other words, as I stated before, those speakers are simply not designed to do really deep bass. They are designed to be efficient and capable of tremendous volumes, enough to be loud in a theater. So in an ordinary home environment, if used at sane volumes, they will never be pushed hard at all.

So, with those speakers, you ought to set them to "small" and use a subwoofer. Unless, of course, you want to chop off the deep bass.

The A7 is capable of very loud bass, but not very deep bass.

 

[AcuDefTechGuy]

Unless there is more than one A7 with significantly different properties, with the A7, the -3dB point is at 54Hz, and it is -10dB at 45Hz. See:

http://www.alteclansing.com/content/ebiz/alteclansing/resources/images/usermanual/a7_MAN.pdf

In other words, as I stated before, those speakers are simply not designed to do really deep bass. They are designed to be efficient and capable of tremendous volumes, enough to be loud in a theater. So in an ordinary home environment, if used at sane volumes, they will never be pushed hard at all.

So, with those speakers, you ought to set them to "small" and use a subwoofer. Unless, of course, you want to chop off the deep bass.

The A7 is capable of very loud bass, but not very deep bass.

I agree.

And that's the company's spec - the actual measured specs is probably even less bass than that.

So I would set those speakers to SMALL.

 

[Lee Batchelor]

Thanks for all the input guys. You've confirmed my suspicions.

- Lee

 

[GranteedEV]

I somewhat agree with what TLS Guy is saying. Ideally a speaker should extend down to around 30 hz imo without any boom, and subs should only be for an LFE channel in movies.

The only thing is that it's expensive to do it right.

I agree with the idea that these "not-so-voice-of-the-theaters" should be crossed over, and also equalized with audessey EQ for flat response. I have some old 3-ways whose bass becomes far more realistic when equalized. With better speakers the audessey has a lot less of an effect.