View Full Version : New capacitors and adding bypass capacitors for L166A

Jeff W.
02-20-2008, 03:55 PM
Greetings to everyone and thanks for all the helpful information here. I am new to owning JBL speakers, but not to vintage audio. I had the good fortune to purchase a pair of L166A's locally that needed some restoration. The surrounds were shot and so my first order of business was to replace them. I also cleaned the pots. Those tasks are done and I am really enjoying these speakers! FYI: I purchased the surrounds from Parts Express #260-978. These are listed for the 2214 12" woofer. The ones they list for the 122A (#260-974) do not fit. My assumption is that they fit the first version of the 122A that came in the L166. If yours have the 9-3/4" diameter cone get the ones I purchased and they will fit perfectly.
Now I would like to replace the crossover capacitors and am interested in the suggestion in one of the posts by Techbot regarding the addition of bypass capacitors. He specifically mentions that the L166 (among others) can benefit from this. Would some of you please make recommendations for specific capacitors to replace the standard 8uf and 4uf in addition to what value should be used for the bypass capacitors. My preference would be to source them from Parts Express since I work one exit away from them and get their wholesale discount as well. However, if there are significantly better alternatives I'm open. My crossover network is the N166-1. Thank You, Jeff :)

02-21-2008, 05:49 AM
Hi Jeff. As you mentioned, there are lots of threads on this subject already available. I've been trying to read 'em all - the one on the L46 crossover has a lot of basic info. I found particularly useful. But here's a "hands-on" experience from last evening. I added .1 mF "Clarity Cap" (trade name) bypass caps to my 075 tweeter networks and, to my surprise, it made a nice improvement. Not really what I expected - it created a more open, less muddled character. Lifting the veil. Interesting. The main cap is a Solen 4.7 uF in a simple 1st order filter. A source for Clarity Caps is E-Speakers.com in California. Have no idea if they are better than the offerings from Parts Express - one test is worth 1000 expert opinions! One other tidbit, the Clarity Caps are physically huge by comparison. A .1 mF is 1" dia. and 3/4" long. The 4.7 uF is 1 1/4" dia. and 1 3/4" long! :blink: Mike

Jeff W.
02-21-2008, 08:59 PM
Mike, Thanks for taking the time to respond and the suggestion on the Clarity Cap. Wow, those puppies are large!

I went ahead and bought some Dayton caps today from Parts Express. I purchased six of their 4uf "Precision 1% Metalized Polypropylene" models, part #027-226. I will use four of these (two in parallel for each) for the 8uf to the mids and the other two to replace the 4uf for each tweeter. They don't have an 8uf. For the bypass caps I bought four of their .01uf polycaps, part #027-450. My total cost was $21.00 at wholesale. If there are other suggestions soon I may return them easily. If there are other suggestions later or I don't like the results it's no great loss. I'll let this be my launch pad and see what I hear and look for more responses here.

I guess you are probably right about how may opinions there may be for brands and such. I was hoping to hear from some folks who had experience with recapping the L166 or L166A specifically. I have not found any post regarding a recap of these models and what was used. I was also hoping that there might be someone who had knowledge of what bypas value might be best in the L166A. In Techbots post on the subject he shows the example of the L112 having used a .01uf so I'll start there since they are fairly similar models. If anyone has experimented with this model in this area I'd appreciate anything you could offer.



02-22-2008, 02:40 AM
I've no personal experience with JBL's Horizon (but lots with Plymouth's :D ).
If yours are model "A" they might not even say "Horizon" anywhere on them.

Several here have recommended AudioCap Theta (#027-700) for bypass, and specifically for bypassing Daytons.
Try searching here for "Theta"

02-22-2008, 11:46 AM
Hi Everyone. I recently acquired a pair of Altec Lansing 1010s. I replaced the 6.8 uf with the Dayton precision ones with a .1 uf Auricap for bypass. very nice. Plus I added a low pass to the woofer. I used a Jantzen 680 uh copper foil inductor for that. IMHO Well worth doing. It still has the classic AL sound. but is a bit clearer.

Good listening

Jeff W.
02-23-2008, 11:45 AM
BJL, Thanks for pointing me in the direction of the Theta. I did a search (as advised) and saw where one of the Senior members (Zilch) specifically recommended Daytons with the Thetas as a bypass for stock voicing with more clarity. This comment was in reference to the L65 Jubal. Looks like I'll be exchanging my .01uf Daytons for the .01uf A.C. Thetas. It seems the .01uf value is recommend universally for many models.

Mine are the L166A's and do not say "Horizon" anywhere. Did you, or do you, own the Horizon (Omni?) that was turbocharged? I worked with a guy back in the 80's that had one. It was a hot little "pocket rocket". :yes:

Bruce, I'm glad you had good results with your Altecs. I hear many folks commenting that the Daytons are worthy even though they don't cost a kings ransom like many others. I have used them quite extensively in restoring AR's, EPI's and Advents.

I am curious as to why you chose the .1uf Acuricap, because I see how universally the .01uf value is suggested. I assume it's not a typo on your part because I don't see a .01uf offered by Acuricap. Is there something about the design of your drivers and network that makes this higher value more appropriate?

Thanks to You Both,


02-24-2008, 08:02 AM
Besides Zilch, member 4313B (formerly known as Giskard) has also suggested Dayton+Theta. I don't expect either of them would advocate following his advice blindly (deafly?) however, with recommendations from them I'd think you ought to at least give the Thetas an audtition.

Member soundboy has also expressed his pleasure with Auricap bypasses on several occaisons. Dunno which size he uses or what's available.

I've had two Horizon econoboxes (no AC or power steering) and still drive one.
My only showroom new car was an Omni, but that was after GLH (a.k.a. "goes like hell") stopped production. I imagine they were quite fun. My mom/brother had the same turbo motor in heavier Laser/Daytona bodies, and they did alright.
There was also an ultra-rare GLH-S by Caroll Shelby which added an intercooler to the turbo.

03-31-2008, 05:37 AM
Jeff did you get the crossovers done. If so how do they sound? Did you go with the .1 or the .01?

I am looking at toying with my crossover's on the L166's. A little test run for me before working on another project.


Jeff W.
07-31-2008, 07:04 PM
Warpig, my appoligies as I have not been back here for a while. I did complete the re-cap and am quite pleased. I am listening to them as I write. At first they didn't seem to sound very good, but after more listening sessions they opened up and now I think they sound fantastic. I had just refoamed the surrounds too. My ears told me that both the caps and the surrounds improve with some mileage :applaud:. I used a .01uf (Audiocap Theta film and foil) for bypassing the mids and tweets.
Now I am on to a pair of L96's on which I'm going to try the charge coupled circuit adapted from the 4313b. I'm studying the posts currently with the info from Giskard and Zilch among others.
This is great fun. I'll have to stop listening to the L166's long enough to refinish the cabinets!