Help with Heathkit AS 101

[mpent]

Hello all,

I am new to this forum and this is my first post. Please bare with me. I have searched the forums for an answer to my questions but I suppose because I am so new to this I am trying to learn the technical basics of sound output, etc on a much more basic level which sometimes gets lost in all the more experienced, technical jargon that is out there (at least for me). Over the weekend, I acquired what I believe to be a very decent pair of Heathkit AS101s. Cabinets are in pretty good shape with the prerequisite dings and scratches that such an item usually comes with after 40 years of use. Grills are excellent. The seller told me that the components are all original and up to spec upon having them assessed by a speaker tech. After getting them home and hooking them up to a heathkit aa-151 and playing with the attentuator, what I am hearing appears to be anything but "up to spec". I opened the cabinets and inspected the crossovers. The L Pads in both crossovers were pretty crusty with a lime green coating which I am assuming is oxidation? Original caps were observed but for one crossover which appears to have had one cap replaced...and it may have been a poor replacement in that the top wire from the cap to the L-pad is bound in electrical tape. I cleaned the L-Pads and all eletrical contacts within the crossover as well as the speaker taps with contact cleaner. Noticed a definite improvement in sound...also, improved the function of one of the attentuators which would not rotate fully back and forth..presumably from the oxidation/crust?

I am brand new to DIY audio. Have been performing alot of research on this model in particular, as well as DIY restoration/rebuild. I understand that cap replacement is an absolute necessity. I am wondering if anyone can clue me in to whether a cap replacement will address the deficiency in sound output that I am hearing. After turning the attentuator all the way up, the sound output from the horns sound pretty good to my ears. Vocals are clear, resonant, and lifelike. What appears to be of issue is the low end sound output which sounds very muddy and bloated (not sure if I am using this term correctly). In fact, it's really hard to discern much low end at all....the sound is not cohesive or well integrated with the high end. Turning the attentuator all the way down in both speakers drastically enhances this problem. High frequencies are very muffled and the bloat and muddiness I hear in the low end is more pronounced and muffled as well (although louder). I am certain that this is not how these speakers should sound considering all that I have read about their sonic capabilities. I have a pair of Klipsch Fortes that I was previously driving with the heathkit amp and the difference is night and day. The Forte's sound very cohesive, crustal clear and just plain wonderful. I purchased the Forte's already modded with Crites diaphrams and new crossovers. So, my question is very basic I suppose...should cap replacement address this problem? Or could I be looking at something more complex?

Thank you.

Michael

[John W]

Hi Michael,
Welcome!
Do you have any pictures of your crossovers? I did a quick search and it looks like the AS101 may be a clone of the Altec Valencia, with an N-809 8A crossover.
If so, it has a schematic like pictured below.
Do you have a picture of the crossover, does it look like the other image?

It sounds like some new capacitors would be a good investment, also sounds like something needs to be done with the L-PAD. If the L-Pad is like the schematic, I'm not sure if you can just replace this with a 8 or 16 ohm L-Pad? Maybe someone with more Altec experience knows.

[mpent]

Yes, the image you posted is that of the crossover in the speakers. They are indeed a basic clone of the Valencia's although if I understand correctly the crossovers in the heathkits are "heathkit crossovers" and not the same as that in the Valencia.

[Earl K]

Actually, the network in those HeathKits should be closer to this ( somewhat dependent on the vintage of the speakers ) ;

Here's the ( older ) thread that this schematic is found in; Driver Replacement for Altec Valencias

- Zilch ( passed away now ) did his level best to improve the status of these models ( via modernizing the components ) ultimately, with mixed results .

- I helped out ( I thought ) with the refurb/modernization of a set of Heathkit AS-101(s) here ! Again ( th efforts ) , had mixed results ( these speakers have just been sold in their original form ) .

- Jack Giff seems to have kept his multi-pairs of Valencias longer than most ( who have refurbed theirs ) . He put BMS 4550 drivers into his ( I believe ) .

[John W]

Here is another link that has a pdf of the original crossover schematic: http://www.audioheritage.org/vbullet...tec-Crossovers

[mpent]

Thanks for your responses. Can anyone please comment on what I am hearing....and whether the cap replacement will drastically improve the sonics (or lack thereof) in my case? I guess I am wondering if bad caps will have this much of an effect on the sonics...and perhaps why the horns sound pretty good with the low end seeming to be most negatively effected?

Rhanks,

Michael

[Earl K]

Michael,

You'll need to read around some, to obtain many view-points about your equipment . Read the full thread behind the link that I provided ( it goes; over to HostBoard ) .

(As a start ); use this sites ( somewhat mediocre ) search engine to search out Jack Giffs opinions about his Valencias ( he has 3 pair that were modded ) .

Also, download the pics of the Heathkit Assembly manual { from here ! ( btw, it's a slow connection ) } so that you can verify your crossovers are wired correctly .

I suspect , that you should rebuild ( at least ) one of those crossovers as a test .

Here's a ( Googled ) opinion about your AA-151.

[mpent]

Thank you much, Earl. I have the assembly manual...actually came with speakers, believe it or not. I did not think of checking to see if they were wired correctly so thanks for the tip. I ordered some new caps and am just going to swap them out....nothing to lose I suppose...and see what effect it has. As an aside...I do enjoy the Heathkit amp...running it as a power amp only with an Eico HF 85 pre-amp. My first venture into vintage tube amps so nothing to compare it too. Regardless, I do like what I hear and hoping to get the AS-101s up to their potential. Thanks.

Michael

[Mr. Widget]

The fact that you like Klipsch Fortes tells me that a pair of properly operating and possibly slightly modded Altecs may be just the ticket. That said, I doubt your speakers only need fresh caps. I would look into new crossovers with added tweeters ... and then about the bass? I imagine that amp isn't helping you at all. I've had Klipschorns, La Scalas, and Cornwalls... all had bloated bass in my opinion with vintage Mac tube amps. High quality SS amps always helped the bass... very high quality SS amps also had mids that sounded as musical as the tubes.


Widget

[mpent]

Hi Widget,

Yes I know the limitations of my amp but I suspect it has little to do with the problems that I am experiencing with the speakers. The Fortes put out acceptable low end..acceptable to me that is, and the heathkit amp has driven them pretty well. I have a pretty dynamic well integrated sounstage with them. I know that there is much better out there...there's always better. This is what drives me nuts about this hobby. Anyway, perhaps I was not explaining what I am hearing very well. What I can say for sure is that the soundstage of the Heathkits is not very well integrated with the highs clear and relatively dynamic, and the lows very muffled..sounding as if you are hearing them underwater so to speak. I am going to start with replacing the caps and then go from there.

Michael

[tjrad]

Having owned AS-101's many years ago.. A couple things to keep in mind. First, make sure that the ports on either side
of the horn have padding. I noticed that the bass on mine sounded terrible if that padding was missing. It really tightens up the bass.
Second, if you can get the speakers off the ground, it will make a big difference with the sound. Might defeat the purpose of the
beautiful cabinets. Third, you are not going to get the crisp clean high frequency like the Klipsch. The horns roll off above 8k and unless
you equalize the high frequency, as I did, you will not hear it. Perhaps add a horn tweeter as someone suggested.

I had problems with the pots in the crossovers. I actually fried them driving them with about forty watts. The amp was big and had
enough head room. It was just too much for the pots. As I recall, I replaced the whole crossover with an Electro Voice 800 hz
crossover. That made a big difference with the sound.

Overall, the sound was great as long as I eq-ed the high frequency. They sounded the best when I drove them with an old Mac 40 watt receiver. Very natural sound. Like being in front of the band..

[mpent]

Thanks all for the feedback. I replaced the caps last night with 1% Daytons, wiring some of the caps in parallel to achieve the specified ratings. My first time soldering..wiring...etc. Don't laugh but really...I'm so excited that I actually got it right my first try. Thank you Internet!!! The difference is pretty huge. Been listening the last several hours, different genres of music and the soundstage is vastly improved. Prior to replacing the caps the only thing that really sounded ok was jazz. I have a Black Sabbath album on now and nothing but smiles here. I ordered new L-pads and will replace those next. Will also check out some other suggestions concerning damping the cabinets. Thank you everyone!

One more question, would the crossover benefit from new chokes and hook up wire?



Michael

[jepstone]

Thank you much, Earl. I have the assembly manual...actually came with speakers, believe it or not. I did not think of checking to see if they were wired correctly so thanks for the tip. I ordered some new caps and am just going to swap them out....nothing to lose I suppose...and see what effect it has. As an aside...I do enjoy the Heathkit amp...running it as a power amp only with an Eico HF 85 pre-amp. My first venture into vintage tube amps so nothing to compare it too. Regardless, I do like what I hear and hoping to get the AS-101s up to their potential. Thanks.

Michael

Hi Michael, I just recently purchased Heathkit AS-101 cabinets without drivers and then picked up all drivers for the cabinets. The problem i have is the cabinets did not have the horn block so i am looking for the dimensions of the horn block in particular. I noticed a manual on this site but it appears to be missing page 4 and i think that has the info i'm looking for. Anybody out there have a complete manual for sale/download. Thanks for the help.

Mike J

[robertbartsch]

I remember building the Heathkit crossovers in early 1973. You saved a bunch by buying the Heathkit system.... I think two speakers were about $700 back then... a bunch of money in today's dollars. The cabs were wonderful.