Rebuilding 3.1TL's Crossovers

Ricardo

During the weekend I completed the xover upgrade for my 3.1 TL's.

This is something that can be easily done by anybody with the ability to use a screwdriver; soldering is very easy and with just a little practice anyone can do it. There are simple tutorials on the web; here's a good link that was posted recently by mlhm5:

http://www.tangentsoft.net/elec/movies/

The cost using Sonicap capacitors was around $350; you can do this using Solen for around $100. I rebuild my 1.2 TL's with Solen and the improvement was well worth it, but this time I followed the recommendation of other members that say that Sonicaps provide a better improvement...I trust them (Carl, Jesse, George Daniel...).

Removing the xover on the 3.1TL is very simple; you just need to remove the passive radiator, remove three plugs from the xover, and remove one bolt in the back of the cabinet while you hold the xover.
Once you have it out, you need to detach the board from the big inductor by unplugging two wires and removing 4 plastic connectors/hooks.

After you have it out, you just need to remove old components and install new ones; because of the size of the new capacitors, you might need to extend the leads; use solid 18g wire for this. You'll need to use a glue gun to fix the new components, again because of their size. I had to connect a couple caps and resistors in parallel to obtain the right value.

That's it; 4-5 hours of work, including checking all the drivers and wiring. How does it sound? I won't comment on this until I have at least 100 hours on them...but I can tell you that what I heard initially is promising

Components used (each speaker):

High Freq:
2 12uF capacitors (Sonicap Gen 1)
1 1.3 ohm resistor -used 2.5 and 2.7 in parallel-(Mills MRA12)
1 0.1uF bypass capacitor (Sonicap Platinum)

Low Freq:
1 24uF capacitor (Sonicap Gen 1)
1 55uF capacitor -used 2 27uf in parallel; asked Soniccraft to target to 55uF-(Sonicap Gen 1)

The 3.1TL has only one tweeter so this is a relatively simple board; also, Polk removed the polyswitches from the xover with this model.

Here is a list of values for the components I removed; be it for age, or original quality/tolerance, you can see that it might be worth it to rebuild these crossovers even if you use cheap components with the right values; the 3.1TL's are the last SDA model, so older models will not be in a better situation:

Specs-Right-Left
12uF cap - 14.2 - 14.4
12uF cap(Mylar) - 12.4 - 11.6
1.3ohm resistor - 1.5 - 1.7
24uF cap-25.8-27
55uF cap-65.4-65.5

Pictures:
I attached some pictures that might help others to do this; you can see the original xover, old components side by side with replacements, front and back diagrams to identify where each components goes, xover with new components, and a wiring diagram.

rskarvan

Glad to see you are enjoying the 3.1TL's.

george daniel

nice work Ricardo,,have you been able to get your listen on yet? As I recall my 2.3's really started to open up after about 50 hours. Have fun

Ricardo

Thanks guys; first thing I played was Allison Krauss & Union Station - Live. I immediately heard some tighter bass, and mids/highs seemed more crisp. When I did the 1.2TL's with Solens, they continued to show improvement (specailly in the bass arena) well beyond 100 hours; from what I hear now, I know already this is going to be a real treat. So far I don't hear anything that tells me that I don't want the bypass there.....but we'll see; I don't want to make my mind until fully broken in, since I know by experience that sound will change. Today I left some XM playing through them....

george daniel

Keep us posted as to your opinion/impression with vs. without the bypass caps (in place of the sm) as mine are still in the x-over as well>

F1nut

Always nice to read about an crossover upgrade. I look forward to your impressions.

schwarcw

Very nice Ricardo! I must be blind, but I can't see that Platinum cap?

I enjoy doing the crossover upgrades. They are a lot of fun. Did you consider upgrading the interconnect cable and terminals?

Ricardo

Carl,
Yeah, I forgot to take the picture of the Platinum outside the xover; if you look closely in pic #5, you'll see it between the resistors and the two white caps; it's black.

I don't plan to upgrade interconnect/terminals, at least not yet. I did change binding posts for Cardas, and am only using one pair for both high and lows.

I don't need 100 hours to know that Sonicaps are better than Solen's; I know that there's still breaking in to happen, but I am SOOOOOOO pleased with what I'm hearing; on top of the bass improvements, mids/highs (I would guess 400 Hz and above) are so much crispier, without being bright/harsh. I adventure to say that 3D imaging is also better, depth location as I never heard. (And Jesse, I think I know what you meant when you said the Platinum impart "artifacts"; as good as the highs are presented, I can sense there is something "extra" there....not bad...just does not sound natural).

In any case, I'll give them 100-150 hours before deciding anything; then I'll bring the Carver's in and see....I am sure that I won't hear that much of a difference in detail....at least not as big as before.

I know many people think that xovers don't make that big of a difference...believe me, they do; I've done two sets already, and well, I wish you could see my grin right now

F1nut

I think I know what you meant when you said the Platinum impart "artifacts"; as good as the highs are presented, I can sense there is something "extra" there....not bad...just does not sound natural).

That's exactly what I meant by artifacts. I noticed that effect with other bypass caps too, not just the Platinum, when used in conjunction with high grade poly's/film and foil, etc. At first, it sounds kinda neat and you think, wow, I'm hearing stuff I've never heard before, but then you realize it makes every piece of music sound the same and shortly thereafter it becomes annoying as hell.

I know many people think that xovers don't make that big of a difference...believe me, they do; I've done two sets already, and well, I wish you could see my grin right now

There's more than a few of us here that know that grin.

mlhm5

Nice job. Nice Pictures. thanks for the effort to post them.

Anyone ever use Mundorfs?

Ricardo

Update; I removed today the by-pass capacitors; a $60 lesson...next time I'll listen to grandpa

F1nut

Hey, the only way to know for sure is to try it yourself.

engtaz

When removing the by-pass capacitors did you just leave it open or replace it with something else? Did I miss them in the parts picture and which is it in the parts list? You did say plural on caps?

Thanks,
engtaz

Ricardo

The by pass capacitors (one for each speaker) are between the resistors and the two white caps that are in the middle of the board; hard to see them because they are hidden by the white caps and they are black.
I just desoldered the leads; you should not put anything in place of them.
They are not in the parts picture.

billbillw

Gosh,
I'm about to do the crossovers in my Mirage M-3, but there is no way I can afford Sonicaps, nor is there room to replace all the Electrolytics with polys. I wish my crossover was as simple as the one shown for the 3.1TL above.

The M-3 has 16 caps and 6 resistors along with 6 choke coils in each channel. I was looking at using Solens because they are smaller and more affordable, but I was told by my brother, who I trust beyond all others, that Solens are really not that great for crossovers. He said their construction is somewhat weak the leads are not even soldered to the foil, they are glued. He said that he wouldn't use them in a high voltage application and he recommended using the Dayton Metallized Polys from P.E. in addition to using their small film/foil caps to bypass. I will use Mills 12w resistors though. Size is really a factor on mine too since the board is very crowded and the crossover is laying flat on the bottom and confined by the speaker cab (no room to extend them beyond the footprint of the board). Due to this fact, there is no way I can completely eliminate the electrolytics, especially in the low pass and midrange. The low pass has a combined 85uf and the mids have over 100uf. I have attached a schematic of the crossover, but its not completly accurate because there were some design changes that were implemented after the initial spec. There is one more 2.2uf BP in the midrange (in parallel to the 100uf BP) and one less resistor in the tweeter section. Also the 6.8 BP in the tweeter is actually a poly. I will have to rely on the improvements offered by using small (.5uf or less) film/foil bypass caps. I'm sure the sound will still be better much better than stock. They use really cheap polys and an abundance of low end Electrolytics. I will replace the electros with newer BPs while I'm at it just to make sure everything is fresh.

Ricardo

I am surprised to hear that comment on the Solen caps; they definitely have a following in the audio community/industry. Including lots of SDA speakers that have been upgraded with them with very good results. I would definitely pick them over a Dayton component, but that's just me

billbillw

HTrookie wrote:

I am surprised to hear that comment on the Solen caps; they definitely have a following in the audio community/industry. Including lots of SDA speakers that have been upgraded with them with very good results. I would definitely pick them over a Dayton component, but that's just me

I was very surprised too, but my brother does a lot of vintage stereo work, upgrades, repairs, etc and I trust him. (He is RadioXTuners.com)

F1nut

Dayton's are made by Bennic and from what I understand are not quite as good as the Solen PB series. Solen makes different grades with the PB being the most popular and the SM and Teflon being the better ones.

Edit: corrected info.

billbillw

F1nut wrote:

Dayton's are made by Solen and from what I understand are not quite as good as the Solen PB series. Solen makes different grades with the PB being the most popular and the SM and Teflon being the better ones.

I've read in numerous spots (including one of your old posts in 2005) that the Daytons are made by Bennic. Where are you getting this new info from?

F1nut

You've got a better memory than I do. I stand corrected!

Here's a link, http://ldsg.snippets.org/appdx-ec.php

billbillw

F1nut wrote:

You've got a better memory than I do. I stand corrected!

Here's a link, http://ldsg.snippets.org/appdx-ec.php

Not really my memory since I just started looking for parts in the last week or so. It comes from searching. The very first google link if you enter solen+ dayton is a post from this forum.

It seems that comparing caps is very subjective. Apparently Parts Express has had DIY events where the different caps are compared and the Daytons do very well.

In the end, I think my brother might be wrong about the Solens because I can't find anyone anywhere complaining about their failure in high voltage apps. My decision will most likely be due to size constraints. In general, the Dayton/Bennics tend to be longer and skinnier than the comparable sized Solen PBs, which will work better in my application.

jakelm

Hey guys. This question might be able to be answered in a long version or a short version , so I appologize in advance.

I keep hearing "bypass" caps. I am currently upgrading my vintage 7b's crossover. What is a bypass cap? And what excatly does it bypass?

I do know what a capacitor does (store voltage and filter), but not sure what you all mean by a bypass capacitor. How would I use them in an aplication like my 7b's xover? Or would you not reccomend it?

Jake

billbillw

Short answer is this: Bypassing is when you wire an additional higher quality small value cap of in parallel with the larger caps. Usually they recommend about 1% the value of the cap being bypassed. Example: You need 20uF capacitance. Use a 20uF metalized poly cap and bypass with a high quality 0.2uF Film/Foil cap. The bypass cap imparts some of its sound to the circuit and will improve over the sound in general, (but not always). The lower quality of the large cap, the greater gain you can get through bypassing. Of course, the bypass cap has to be of very good quality.

jakelm wrote:

Hey guys. This question might be able to be answered in a long version or a short version , so I appologize in advance.

I keep hearing "bypass" caps. I am currently upgrading my vintage 7b's crossover. What is a bypass cap? And what excatly does it bypass?

I do know what a capacitor does (allow dc volts to pass), but not sure what you all mean by a bypass capacitor. How would I use them in an aplication like my 7b's xover? Or would you not reccomend it?

Jake

jakelm

Thanks Bill. So if I were to go with a (lets say) Dayton cap of 34uF. Then I would bypass it with a Sonicap of .3 or .4uF for better sound? But not in all cases does this help?

Then wouldnt it be better just to go with a higher quality big (main) cap and not bypass at all?

In my aplication where there are only 2 caps per crossover, I might as well go with better main caps. And not use bypass caps at all.

billbillw

I wanted to elaborate on what capacitors do in a crossover circuit. They don't really let DC volts pass. There shouldn't be any DC voltage coming through your speaker wire. If there is, you got problems with your amp and your speakers will eventually have fried voice coils.

The caps are used to filter by absorbing the peaks in the AC signal, which attenuates the response. The size and use of the cap determines what it filters out. The simplest 1st order crossovers just use a choke (coil) on the low driver (filters out high frequencies, lets low pass) and capacitors are used on the high drivers (they filter out low frequencies and let highs pass). Mid ranges use a combo to create a "bandpass". When things get more complex in 2nd and 3rd order designs, you can have caps shunting high frequencies to ground and doing other mysterious things that are above my head.

jakelm

Bill I re-read what I typed....I corrected myself.

I think Solens will do fine in my application, with no bypass.

billbillw

jakelm wrote:

Thanks Bill. So if I were to go with a (lets say) Dayton cap of 34uF. Then I would bypass it with a Sonicap of .3 or .4uF for better sound? But not in all cases does this help?

Then wouldnt it be better just to go with a higher quality big (main) cap and not bypass at all?

In my aplication where there are only 2 caps per crossover, I might as well go with better main caps. And not use bypass caps at all.

You'd probably want to go better than a sonicap for the bypass. You want the really good stuff like film/foil. Yes, you'd be better off using a single high quality cap, but the problem is that the very best caps are not available in some of the bigger sizes and if they are, they are very cost prohibitive.

jakelm

billbillw wrote:

You'd probably want to go better than a sonicap for the bypass. You want the really good stuff like film/foil. Think Mundorf, Hovland, Cardas, Auricap. Yes, you'd be better off using a single high quality cap, but the problem is that the very best caps are not available in some of the bigger sizes and if they are, they are very cost prohibitive. (a 30uf Auricap is about $60 each)

In a speaker, the weakest link is what the speaker will sound like. Doesnt it get to point to where the caps are better than the drivers themselves and its pure overkill?

billbillw

jakelm wrote:

In a speaker, the weakest link is what the speaker will sound like. Doesnt it get to point to where the caps are better than the drivers themselves and its pure overkill?

Probably true. In your case, I'd get Daytons or Solens and maybe try with and without bypassing with the Dayton Film/Foil caps. They are fairly cheap to try. If you don't like the sound with the bypass caps, its not much lost. You should also realize that when comparing caps, some designs will always sound better than others regardless of the brand. Example: Metalized poly will sound better than electrolytic. Film/foil will sound better than metalized poly, etc.

Ricardo

If you have a good quality capacitor a by pass is not required; this is just theory, but it worked like this in my case.

jakelm

I think the Solen is high quality enough (and not too expensive) not to have a bypass. Anything should be better than 25 year old Maylar and electrolytic.