Zero Distortion: Altec Assault and the Magic of Misho (Audio Antiquary)
- Thread starter bonzo75
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Ked ,
"I don't like any horn that has a horn loading in the mids and then a closed box below"
and then
"Leif has implemented an active front firing sub that takes over from the dual FLH and goes from 75Hz to 15 Hz. Is it required, and without the space would I add a sealed sub? Yes I would. Would I miss anything? I doubt"
Isn't that contradictory ?
You say also that you prefer Martin Logan hybrid desing more than horn hybrid desing. I have listened to ML only at shows but the shortcomings of ML desing are for me more important than say AG Duo XD series, especially their low sensivity is a serious problem. Imho high power ss desings with less effective speakers introduce more real distortions ( not on paper ) than SET's with effective horns.
Btw I also like the mids and tweeter driver from Universum III but their downard firing horn spoil the whole presentation .
It is the reason I do not consider them as a good replacement for Duo Mezzo XD.
"I don't like any horn that has a horn loading in the mids and then a closed box below"
and then
"Leif has implemented an active front firing sub that takes over from the dual FLH and goes from 75Hz to 15 Hz. Is it required, and without the space would I add a sealed sub? Yes I would. Would I miss anything? I doubt"
Isn't that contradictory ?
You say also that you prefer Martin Logan hybrid desing more than horn hybrid desing. I have listened to ML only at shows but the shortcomings of ML desing are for me more important than say AG Duo XD series, especially their low sensivity is a serious problem. Imho high power ss desings with less effective speakers introduce more real distortions ( not on paper ) than SET's with effective horns.
Btw I also like the mids and tweeter driver from Universum III but their downard firing horn spoil the whole presentation .
It is the reason I do not consider them as a good replacement for Duo Mezzo XD.
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Marslo - the FLH I am referring to start and end anywhere between 500 going down to 40. I am saying I am fine with the sealed subs below 80, or 60, to adjust to the room. If I had Leif's space I would do it his way
I have never heard ML sound good at shows - in fact awful. I don't know why. Ron will tell you the same, and he likes ML too
I have never heard ML sound good at shows - in fact awful. I don't know why. Ron will tell you the same, and he likes ML too
I feel like there is a mix-up every time this is discussed. The dual FLH's are not bass, they can be considered mid-bass. The altec ones are not horn loaded below 150hz to 200hz depending on the model.
If you can go down to 80-100hz with a front loaded horn, that is good enough, and having dual throats are not a must. Below that if you want true horn loading down to 20-30 or 40hz, you will have a giant horn that you can not time align with the rest of the system or you should go active and/or dsp. Some still go for what they think are big horns and have large throats with multiple drivers. Sadly, most of them are actually working as direct radiators around bass and not horn loading (except very few really large ones)... The there is also folded bass horns like Klipschorn or a lot of pro-audio bass operating between 40-60hz to 120-160hz.
I also think having horn load on fundamental frequencies is what makes a horn system worthy, and that is between 80 to 500hz roughly. So, all in all you do not need horn bass, you need horn mid-bass.
If you can go down to 80-100hz with a front loaded horn, that is good enough, and having dual throats are not a must. Below that if you want true horn loading down to 20-30 or 40hz, you will have a giant horn that you can not time align with the rest of the system or you should go active and/or dsp. Some still go for what they think are big horns and have large throats with multiple drivers. Sadly, most of them are actually working as direct radiators around bass and not horn loading (except very few really large ones)... The there is also folded bass horns like Klipschorn or a lot of pro-audio bass operating between 40-60hz to 120-160hz.
I also think having horn load on fundamental frequencies is what makes a horn system worthy, and that is between 80 to 500hz roughly. So, all in all you do not need horn bass, you need horn mid-bass.
This is not correct. The 817s I heard are going down till 100 at least where the vents/bass reflex then join in. You can also increase the size of the box to increase extension. Silvercore's FLH were going down to 40 though starting much lower. Leif's go down to 75
Yes about the mixup, I am referring to 500 to 80 region for FLH as mentioned
Even small monitors won't stop at 150
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Small monitors are not horn loaded, this is irrelevant. Physics stand, even 150hz full horn loading means about a meter wide mouth the least, and about a meter depth.
75hz of Leif's midbass is great and there can be many solutions that will work great below 75! You can have folded horns, tapped horns, even large horns that are a little out of alignment, it wont be heard that much at around 75hz.
The 816 is horn loaded from 200hz (see attached reference sheet), I would be very surprised if 817's are horn loaded an octave below! How did you measure, can you chare the impedance measurement for us or do you think you are able to distinguish just by hearing which frequencies were horn loaded?
Increasing the box size will give you lower frequencies but they will not be loaded by the horn. The horns depth, throat and mouth size sets the frequency to load, the lowest you can reach is its cf point if you reactance annul. For ex. my mid-bass horn which has little more than 1 meter mouth and has 1 meter depth, with a reactance annuled back chamber can go as low as 110hz.
All monitors play below that but I do not get what it has to do with anything. The mid-bass I have is 109db efficient to its cutoff, that is why it is that size.
Attachments
816 is one woofer. No, don't have measurements.
When you increase box size, why can you not increase depth and mouth size
The intriguing thing for me in this discussion is the power range of the orchestra is 80 to 200 Hz – precisely where these dual FLH’s seem to excel. Reproducing the amount of air that gets moved in this range is very elusive.
You can increase the depth and make the mouth bigger, that means you are building a new and bigger horn, and that is the way to load lower.
If you just increase the rear chamber size, the you get direct radiated bass from the driver but it is not horn loaded.
The better way to do it has been found so long ago, and is called reactance annuling. You actually turn your woofer into a kind of compression driver
You adjust the fc of to fs and gain about half an octave of more loading down to cf! To do that, I built my backchamber out of slices, so it was adjustable. I took of one slice at a time and measure the impedance and continue until I got it right.It wont go as low as building a bigger box and with annuling you actually end up with a very tight chamber but with the benefits of horn loading and lower extension than before.
Yes that is key, which is why cello, bass section, tympani, piano, brass, are Superb. You seem like someone who is not familiar with dual FLH but if you picked that up by reading I am very impressed by your ability to digest new information. Personally I just scroll over what I have not heard
The mouth is larger as the bottom plate of the horn is angled but 150hz again is surprisingly low, furthermore their literature said 120hz! We can simulate it, the plan is out there, at least to have a theoretical idea.
I would love to measure and inspect and learn from a real one if it performs as it claims. Let me look for one after pandemic curfews and travel limitations end. I have never measured an A7.
Once more, I love these vintage horns, I just want for me and for everyone else to be aware of what is going on. I am not commenting on sound quality at all. I am talking about physical properties. I generally like to start where I can have a quantifiable and theoretically correct point.
I didn't like the few A5 I heard, there was no Midbass magic and the handover to the vent below was easily heard. Whether it was due to cross over, electronics, etc I cannot say. I think the bad implementations of altecs are very poor sounding.
well, I think this is spot on - Ked does not like Duos ( they go down to 170 Hz without any crossover, which is essential to me) and prefers Trios with big FLH going down to around 100 Hz and then the big basshorn ( sub) reproduces deeper bass.
So the gap is very narrow ( around 70Hz) between Duo and Trio but critical for him.
He has a good ear so he is probably right about the importance ot this part of frequency but I listened to Trios with small basshorn ( the same I have had in my Duo Omega G2) in AG HQ and the presentation was for me less convincing than Duo Mezzo.
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You are correct in that I am completely unfamiliar with dual FLH or even horns for the most part. I’ve heard Avantgarde Trios and Duo’s but they were nothing I would want to live with. I became intrigued with Altec’s by Jeff Day’s writings at Positive Feedback. Not ever having heard these, I went to YouTube and started plowing through the multitude of videos of A5’s ad A7’s. For the most part, they all had the same problem – the level of the horn is way too prominent and makes the whole thing sounded terribly unbalanced. After a bit more research it became apparent that you can’t use the stock crossover with these speakers since they were voiced for use in a movie theater sitting behind a curtain. I surmised but don’t know for sure that the few videos that sounded good had done something with the crossover and the ones that did not had used a stock cross over. That assumption may not be correct but it’s a starting point. I need to travel to heard these with recordings I am familiar with but that will have to wait for things to open up again.
Bonzo,
Would you consider a bass section of Avantgarde Duo Mezzo an FLH?
I have Duo Omega G2, BTW, and I use stereo pair of JL Fathom 112 subs with an active crossover to supplement main speakers and to correct some room related problems
Theoretically, yes. It does have a short horn flare in the front and and two 12 inch drivers. Does it sound similar, no - it could be for different reasons, am not sure, maybe the drivers, maybe the size is not big enough, and maybe it is active at 170. I always find the trios more effortless, and that is possibly a function of the larger size of the lower midrange horn or the fact that the driver is less stretched since in trios there is a midrange horn and a lower midrange horn. I don't understand what the CDC/CPC handling of the crossover is.
The dual FLH designs I liked are all big. Big drivers, big mouths, big chambers. They all have a simple passive crossover.
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Makes sense,
Frankly, your idea of custom FLH seems very attractive to me.
If I knew people able to complete that project for a reasonable amount of $$, I wouldn’t hesitate for a moment.
Maybe after you finish yours, you’d be able “ to share”?