New Heathkit AS101 owner - First post.

[alancohen]

Well, that is exactly what I am doing and I can't hear anything bad, but I don't know anything better, so I guess ignorance is bliss.

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.

[gearfreak]

I assume it has something to do with sound waves moving in an air medium through a restricted space.

*I think I misquoted, and was intending Fo, not Fc in my original.

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).

[voice of the theater]

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!

[alancohen]

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.

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!

[voice of the theater]

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.

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!).



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...

[cradeldorf]

*I think I misquoted, and was intending Fo, not Fc in my original.

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).

Also think of the slide trombone, the longer the distance between the throat and mouth....

[alancohen]

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?

[Altec Best]

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.

[alancohen]

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?

[alancohen]

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.