Indeed!! I joke with my father all the time that he was blessed with a tin ear. Audio systems are much cheaper for him! I however, can hear the difference. It's a curse.Quote:
Originally Posted by VolvoHeretic
Printable View
Indeed!! I joke with my father all the time that he was blessed with a tin ear. Audio systems are much cheaper for him! I however, can hear the difference. It's a curse.Quote:
Originally Posted by VolvoHeretic
*I think I misquoted, and was intending Fo, not Fc in my original.Quote:
Originally Posted by alancohen
Afaik, mouth area ultimately (perhaps as part of the expansion coefficient) limits Fo (cutoff). e.g. Tubas have bigger bells than trumpets. So you must consider that along with the length (path should be at least 1/4 WL, iirc)
I don't want to go on spouting bad horn math or mistruths , so I'll leave it to pickup later (or someone else can continue).
Here are some Altec horns that work well with a 300 hz crossover point. I know you're not in the market Alan, but I ran across these in my area today and thought you might like to see them......
2 Altec 311-60 horns!
Thanks VOTT! Yeah, I think I have some 288s (291s) and a pair of 1005Bs in my future someday, but not now. I'm not ready for a dedicated audio room yet. I'll quote Bruce Rozenblit, "Audio gear should be designed to share space with human beings. It has to fit in a room and have space left over for people." Besides, my audio budget is stretched pretty thin. I'll spend a year or two listening to what I have and in the mean time build up the reserves. I find you can get the best deals when you're not in a hurry and can wait for the right situation to come along.Quote:
Originally Posted by voice of the theater
Speaking of Bruce...I just fired up my 15W OTL this morning for the first time! Tubes are burning in and I will set the bias after another cup of coffee. So far so good. It's not making sound yet, but at least it's not smoking.
DSCF0736 | Flickr - Photo Sharing!
Wow--that amp looks great! Hope you don't mind, I lightened the photo with photoshop to get a better look (although your darker photo does look really "cool" with the glow of the tubes!).Quote:
Originally Posted by alancohen
http://www.hostboard.com/forums/hbmc...2012/11/59.jpg
BTW, I wasn't suggesting that you need to upgrade--just thought that since you mentioned you were interested in a lower crossover point that you'd get a kick out of seeing a pair of Altec horns (I don't see 311's locally every day) that were designed for a lower crossover point. My AS 101's were the "Cadillac" speakers in my home for quite a while--I was in no hurry to upgrade them because they sounded so phenomenal once I did the crossover restoration. I'm glad to hear that you plan on keeping yours as your main speakers for a good year or two--who knows, after you hear them biamped you may decide to keep them as your "first string" speakers even longer. A lower crossover point isn't necessarily an upgrade anyways--I used to own a pair of A7-500's back in the 90's (511b horn/500 hz crossover) and my AS 101's sounded considerably better than they did -- especially for home hi fi use (and they both had 416 woofers). I currently own Model 19's with a 1200 hz crossover (yes, the 416's play up to 1200 hz), and the Altec midrange magic is amazing on them. The mids sound phenomenal and the crossover is very smooth and seemless at 1200 hz. I'm very interested to hear what the AS 101's sound like bi-amped. Mine sounded so great with the restored crossovers, I can only imagine what taking them to the next level will do...
Also think of the slide trombone, the longer the distance between the throat and mouth....Quote:
Originally Posted by gearfreak
Update: So...I got my 15W OTL wired and fired last night. I got the wrong transformer with the kit and it was quickly replaced. The tubes are still buring in, but it already sounds amazing. Near as I can descibe it, it just sounds...naked. An analogy would be trying to read the paper with my 50+ year old eyes and then putting on my reading glasses. I don't have to try and hear detail, it's just presented to me my ears.
I love how the bottom is just there. It used to be that if I wanted to "hear the bass" I had to hit the ol' loudness button, turn the bass tone control up, raise the left side of the EQ or at the very least, turn up the volume. With this amp, at very modest sound levels, when a low frequency passage comes by it just presents itself...in all it's thunderous glory. As a matter of fact, I do not have ANY tone controls whatsoever now. Nor do I need any. Sweet.
But I do have a problem. I use an audiophile pressing of Larry Carlton's, "Alone, But Never Alone" as my component test source since I know it well. The lows and mids are spectacular and are obvioulsy well engineered. But there are small chimes used in several songs and now I notice their presence seems muted. They just don't sparkle the way I'm sure the recording engineer intended. I never noticed it as much before because my other amps must have muted everything else to a similar degree.
So I'm wondering if this high end limitation is a function of the stock XO, or the 806A/811B. I remember reading a bunch of Zilch's threads where he pounded on the high-end roll off of the Valencia's (and Heathkits too). He seemed to think that a reworked XO would help. If that's the case then my bi-amping with active crossover might alleviate the issue.
Thoughts?
It could be a limitation of the 806A.. It isn't one of my favorites.. You can add a super tweeter or change the driver to a 902A-B/ 802G.. IIRC the 806A's roll off around 14 Khz.
That sounds about what I'm hearing. All the spec sheets say it goes 500-22K. Go figure.
I think I'll go the super tweeter route and tri-amp the system. This way I really have complete control over attenuation, delay, slope and XOer point. The 3W cathode follower I have now would be put out to pasture after I build the 300B monoblocks anyway. It only falls of 1dB at 50KHz so it should be fine to drive the super tweeters. I'm smelling a messy wiring nightmare.
The question is: do I cut the Heathkit baffles to install the tweeters inside, or arrange them somehow on the outside?
I remember Zilch recommending the BMS 4550s over Altecs. Thoughts? If I go with a higher response CD I could save the add'l amp and use the extra output channel on my XO to drive a sub.
BMS 4550 1" High frequency Compression Driver - BMS 4550 - BMS 4550 1" high frequency compression driver. BMS neodymium 4550 high frequency compression drivers are available here.
I bought a pair of these new in 1974. I can still remember soldering the crossovers and installing drivers. I think I paid about $600 or so, if memory serves me well.
...like a dope, I sold them in 1999. I missed them so much, however, I bought a pair of Velencias that have the same guts,,, You should consider installing casters on the cabs...
I find tweeters ruin the imaging of horn based systems ( unless crossed above 10K ) / so I discourage their use .Quote:
Originally Posted by alancohen
Also, since I like the sound of aluminum diaphragms much more than the plastic type frams, I'd be inclined to seek out an 802 / 902 variant that could work with your AS101's .
( Strictly speaking ),a reworked XO is not going to bring back something that's missing ( though with biamping, one could conceivably suppress the midrange enough to give the HF a fair chance at being heard ) .
One needs to suppress the midrange something in the order of 12 to 15db to get the the HF on an equal footing . See ( Zilchs work ) below ;
http://www.hostboard.com/forums/hbmc.../2012/08/3.png
If 14db of midrange suppression is employed, the whole horn circuit will be too low in level when compared to the woofer . It'll be something like 90db HF over 96db LF ( clearly a mismatch between the highs & lows ) .
Using an 8ohm driver ( or 8 ohm diaphragm in your existing 806 ) over an 16 ohm woofer helps reclaim most of that differential . That'll necessitate a rework of the crossover to accommodate the mixed 16 ohm and 8 ohm loads ( LF & HF respectively ) .
:)
Reworking the stock 101 Xover would mean employing something like the HF leg of this following network ;
http://www.hostboard.com/forums/hbmc.../2012/12/1.png
Then one would want to build up Altec's ( classic ) midrange suppression network ( the HF portion of the following compensation network ) and insert it inline ( after the Lpad I suppose ) .
http://www.hostboard.com/forums/hbmc...2012/05/50.jpg
I agree--I'd replace your 806 drivers with 802-8G drivers (or 902-8A). Both have a nice extended high frequency response and will sound great with your 416 woofers. I own a pair of Altec Model 14's with 902-8A drivers and two pair of Model 19's with 802-8G drivers and both have a great extended H.F. response--plenty of sizzle and no need for a tweeter. Just ask AB about his Model 19's. The AS 101's are great speakers with great bass, mids, and treble up to around 13-14k. Past that is their weak point. As AB stated, the 806 drivers roll off at around 13-14k. I know the specs for them say up to 22k, but the response past 13 or 14 k drops off steadily and isn't really usable. BTW, I mentioned this potential upgrade to you on page one of this thread (in post number 2 of this thread). Zilch was a Valencia owner, and this was part of his recommended upgrade for Valencias. Since you're biamping, you won't need to replace the AS 101 crossover with the Model 19 crossover--which was the other part of Zilch's recommendation for this upgrade.....Quote:
Originally Posted by Earl K
Quote:
Originally Posted by voice of the theater
Big thanks Earl and VOTT!
I'll take your(pl) recommendation and just get the 802-8Gs from GPA. I can tri-amp tweeters, but like you said, why mess with the 811s in their sweet spot. Besides, if I can get enough high end out of the 802s and bi-amp, then I have an extra channel left over on the active XO for a sub...if I choose.
I'm not sure whether or not I'll sell the 806s yet. I'd like to keep them in case I ever sell the HKs, but I hate unused stuff laying around. I have no room for extraneous gear. I can't imagine I'd ever sell the HKs though. I know, famous last words.
I can't recommend this enough... Always keep your original gear,especially when you have all the original parts..You will always receive much more money reselling vintage speakers if they are all original.. And besides, once broken up another original pair will bite the dust.. Like Altec they won't be making any more new ones. :wink2:Quote:
Originally Posted by alancohen
BTW- If you ever do decide to add a super tweeter the horn in the heath is up high so you wouldn't need to cut the baffle you can simply mount/lay the tweeter on the top of cabinet without any cabinet cuts without any issues IMHO..
But as has been already noted changing driver/crossover seems to be the least amount of work to get were you would like to be.
I hear ya. It's not like they'll take up a lot of space.Quote:
Originally Posted by Altec Best
So just thinking out loud: If I'm dropping $500+ on the 802-8Gs, what about a pair of Altec 3000 tweeters for about the same or less $$$ instead? I hear they're da' bomb.
I love the mid to mid/highs on the 806s. I have the amps, I have the XO. I can crossover the 416s, the 811s and the 3000s anywhere I want. I can fine tune the delay, the XO slope, the volume.
Or just keep things simple with the 802s?
I also have these:
http://www.hostboard.com/forums/hbmc.../2012/12/2.jpg
http://www.hostboard.com/forums/hbmc.../2012/12/3.jpg
Similar to University HF-206s?
Worth a try before dropping the cash?
Alan,
(A) I just reread this thread . A couple of things stick out .
(i) It seems you have a DCX2496 available for biamping .
(ii) It also seems you have available another amp that you can commit to the HF circuit if you actually do biamp .
(iii) Your AS-101 have 8 ohm components loaded into them .
(B) Upon review ( for you to get more HF ) I would simply biamp these 101(s), using your available electronics ( & not buy any new drivers or diaphragms ) .
(i) Build up the HF portion of the midrange suppression circuit ( that I posted above ) , put it inline with the horn-driver , turn up the HF amp to make up for the lost sensitivity and then take a listen .
(ii) The new balance ( between mids & HF ) should be more to your liking .
(iii) This is cheaper & faster to do when compared to trying to integrate a tweeter ( & should sound better ).
:)
PS ; Forget about those Ovation horn drivers ( they'll be dying by 8K for sure ) .
AS-101 Schematic
That makes perfect sense, Earl, but it might not be a good option in my case. The amp(s) I plan on driving my HFs is a pair of 1W 300B OTL monoblocks. At 1W I need as much of the efficiency that a HF CD can afford. If I'm toning down the mids almost 14dB then I think I'm shooting myself in the foot.
FWIW, once I build the 300Bs I will have 3 amps available for tri-amping. That would allow me to boost the above 14KHz range through a tweeter without muting the 800-14Khz mids through the 811.
But that might defeat the gloriousness of the 300Bs by chopping them off at 14Khz and not allowing them to reach higher. And I'm not building 4 300Bs!!
I think the 802-8Gs might be the answer. It will allow the 300Bs to play all the way up, I won't be disturbing the imaging by adding another component and I'll be able to maintain the high efficiency Altec horns are known for.
I think you hit the nail on the head here. Not to mention, your rationale is very much in keeping with Altec's philosophy regarding the 802-8g/tangerine phase plug....Quote:
Originally Posted by alancohen
http://www.hostboard.com/forums/hbmc.../2012/12/4.jpg
http://www.hostboard.com/forums/hbmc.../2012/12/5.jpg
Quote:
Originally Posted by alancohen
A couple of things to make note of ( before you pull the trigger on any new drivers or tweeters ) .
(i) You're repeating verbatim ( as if it's somehow gospel , info that can't be substantiated ) that your current drivers are somewhat flat out to 14K .
- I can assure you they are not flat out to 14K / ( almost 15db down at 14K compared to 1K, is not my definition of the word "flat" ) .
- I guess the message contained within this Zilch graph ( that I posted earlier ) simply didn't register with anyone here .
- The existing curve ( on your 811/806 combo ) won't be that much different from the following red trace .
- If you want to use tweeters, you'll want to cross-over in the 6-8K region ( if you go with a raw 811/806 response ) .
- Here's that graph again ;
http://www.hostboard.com/forums/hbmc.../2012/08/3.png
(ii) If you do get some 802-8G drivers, you'll need to tone down the mids 10 or 11 db to be somewhat flat out to 14K ( according to some testing that I just did with a 802-8T loaded with a 34647 diaphragm / I'll post pics sometime later today ) . The 806 requires even more midrange attenuation .
(iii) I'd suggest you get some measurement gear before buying anything like other drivers or tweeters.
- FWIW, REW is still free & it works well on a Mac ( under some strict conditions that dictate what sort of external soundcard you can use ).
- Also, a USB based test-mic is in the works ( from the MiniDSP people ) which will come with a unique calibration file ( for each & every device sold ) making the mic useful for measurement purposes. It'll be @ $100.00 ( from what I've read ) making the entry cost for getting serious data, cheap as Borscht !
:)
That is certainly a sober recommendation, Earl.
I have a USB-based Samson Go Mic. It might do the job well enough. I also have a Macbook Air. I downloaded REW, but I don't have the patience at the moment to set it up or figure out how to use it. Can these programs play a pink noise signal through the headphone output and record it back though the USB mic?
Yes ! ( REW has a great signal generator built into it )Quote:
Originally Posted by alancohen
:)
I did some horn compares that you might find interesting:
Here is a modern HF driver (B&C DE250) on three different Altec horns:
http://imageshack.us/a/img35/8195/horncomparison5.png
And here is the same driver compared to an Altec 802D on an Altec 511B horn:
http://img407.imageshack.us/img407/7...omparison4.png
All of these are "barefoot" driver measurements (no XO, EQ, etc.)
I also have some 902 and 802-8G graphs here somewhere....
Alan,
Here's the pic I promised .
My apologies for it's "clutter" ( hopefully the message doesn't get lost in the info ).
http://www.hostboard.com/forums/hbmc.../2012/12/2.png
The red and teal colored traces shows an 802 ( on a Radial horn ) with a 2-pole HiPass ( similar to the AS-101 values ) coupled with the HF portion of the 30923 "Equalizer Network" . I'd say this network offers 10 to 12db midrange suppression .
http://www.hostboard.com/forums/hbmc...2012/05/50.jpg
:)
I think I got REW working a little. Here is what I got:
http://www.hostboard.com/forums/hbmc.../2012/12/6.jpg
Put that file into a 60-70 db vertical scale, apply 1/6 ( or 1/12 smoothing ) & then repost the graph.
:)
Huh???????
OK...found it I think:
http://www.hostboard.com/forums/hbmc.../2012/12/7.jpg
- A couple things to check out ( to investigate the "suckout" between 800 hz & 1600hz ) .
(i) Replace the horn driver with a single 8 ohm resistor & run another trace ( to see ho high up that woofer is working ) .
(ii) Do the same with woofer ( replace it with a single 8 ohm resistor ) and capture a sweep of the horn circuit on it's own ( to see how low it's going ) .
(iii) Switch the polarity of the horn circuit and then capture a sweep of the horn & woofer together ( to see if the stock polarity is actually "adding" within the crossover region ) .
:)
I moved the speakers around and centered the mic. This seems about what I have:
http://www.hostboard.com/forums/hbmc.../2012/12/3.png
It's hard to get a quiet room here. I live on a highway and the roads are wet and cars are going by. That's why I'm moving!!
- A 135 db vertical scale is the geological equivalent of "fools-gold" .
- At some point you'll need to grasp the concept that the idea is to get a trace that is balanced between being "overly critical" & "simple delusional gratification" such as you are now showing ( manipulating the vertical controls will ping pong between the 2 extremes ).
- A "Pro" Range was established as 50db to the vertical ( decades ago ) by the IEEE ( back in the early 60's ) for a certain sized pic .
:)
> ( I think that's enough for now )
I see what you're saying...I think. Here is the same plot adjusted to a similar range you posted earlier:
http://www.hostboard.com/forums/hbmc.../2012/12/4.png
This is 3 separate measurements overlaid.
I wish there was a way to overlay a keyboard diagram over those traces so that I had a clue what I was looking at.
Quote:
Originally Posted by alancohen
Try to run your sweeps at night.When it's quieter.
I will. Now that I've learned a little about using this new toy, I will certainly play with it more. I did notice with the software that just after hitting the Start Measuring button I hear a little pop...almost like a switch being flipped or a turn table needle finding the groove. It does make the level indicators jump. I wonder if this is being recorded in the results.Quote:
Originally Posted by Altec Best
Sadly, there is no quiet time where I live at the moment. I have this neighbor that thinks he has the coolest sounding motocycle ever. He stripped all the exhaust off and is running straight pipes. He sits at the light in front of my house and just revs it and revs it. Either he just thinks he's cool, or he can't keep it idling because he amputated all the back pressure from his engine. Regardless, it sounds like crap. If I had a little 22 rifle I'd plink a hole in his gas tank.
There is also a rock quarry across the street. From 6AM till 10AM there are huge dump trucks pulling out on my corner full loaded and winding out their gears. Even on Saturdays.
And the traffic runs steady till the wee hours. I guess you get used to it, but it's really noticeable when you try to analyze your speakers!! Last night was rainy so the noise was particularly loud.
I'm hopefully closing on a house in a week or so that is out in the woods and will be much more conducive to quiet audio time. The only noise there will be the crackling of the wood burning stove and the crickets.
Alan,
> Glad to see you are now measuring things ( having got your Samson USB mic to work with REW ) .
A few things ;
(i) You will still need to acquire a test mic that comes with a unique calibration file ( that is then loaded into REW ) to correct for the mic's deficiencies ( if you want to believe that what you measure is accurate ) .
- Test mics typically use small diameter ( 1/2" & smaller ) , omni-direction capsules .
- I looked briefly at the available Samson USB based microphones and all the ones I saw don't suit the needs for accurate data acquisition ( they're all aimed at the M.I. market having large capsules & bodies ) . Samson USB Mics
- Here's the MiniDSP mic previously mentioned .
- One ( apparent ) weakness ( of this unit ) is the need to have the users computer quite near the mic . Another is the maximum sampling rate of 48K ( which limits HF distortion measurements more than anything ) .
http://www.hostboard.com/forums/hbmc.../2012/12/8.jpg
(ii) The exaggerated HF roll-off shown might be there ( or may be less ) . It's all dependent on the linearity of your test mic ( as well as your testing methodology, ie ; whether the mic was pointed directly at horn & was within it's coverage angles ) .
(iii) Display standards ( for test data ) is a bit of a moving target . Much of it is referenced to the older paper print-outs produced by B&K ( who used a 50db vertical axis ) .
- Your latest pic well displays the HF roll-offs ( though the horizontal length of the pic might tend to exaggerate their severity ). See;
http://www.hostboard.com/forums/hbmc.../2012/12/4.png
vs this one lengthened by 50% ;
http://www.hostboard.com/forums/atta...p;d=1354547946
> There is a bit of art & craft to data display ( when all is said & done ) .
(iv) For the small cost of making up the Altec 30923 HF compensation network, I would encourage you to do so ( build at least one ) . Insert it just before the compression driver ( you'll likely need to fully turn up the Lpad on the horn ) and then remeasure & take a listen ( you should see & hear that you have reclaimed a lot of missing HF & UHF in that part of the circuit )
http://www.hostboard.com/forums/hbmc...2012/05/50.jpg
:)
Will do Earl. I'm always a fan of the least invasive (expensive) mods firsts. Can't hurt to try.
Question: What wattage on the resistors? 2W, 5W? And I assume that C-1 is a simple film capacitor?
And I just checked the specs on my Samson Go Mic. It only goes to 18KHz so that could be the reason for the exaggerated HF fall off.
The sample rate of REW is either 44.1K or 48K. Which is better?
And I just ordered the MiniDSP UMIK-1 as recommended. Seems like a pretty good deal for the $75+$20 shpg. The DPA 4007 @ $1925 is a little outside my budget.
> I'd use 5 watts minimum ( 10 watts if you play things loud ).Quote:
Originally Posted by alancohen
> A simple 6uF Dayton Polypropylene cap will suffice .
> 48K is slightly better ( and as a habit is better to use for all sorts of software based audio files ).
:)
I can't seem to find a 6uF Dayton. They have a 6.2. OK?