SDA SRS 4.1TL Upgrade

dorokusai · June 2006

You may use whatever brand you want, just keep the spec's in mind.

The values are a constant, the sonics are subjective.

The recommendations in regards to upgrades so far are solid and proven to the users, other than that, it's all you. Sonicraft is a giant killer.

BSUfbfan · June 2006

schwarcw wrote:

BSUfbfan,

I'm curious to know how you proceeded with your crossover upgrade?

I have a pair of CRS's and I plan to upgrade the caps and tweeters, but I don't think I want to ventrue into the project that Jesse did to convert to a 4.1.

My plan is to use the Solen caps because fo the size difference compared to the Sonicaps. I've used the Sonicaps in my SDA-2's and SRS 2.3's. I figured that I wanted to try something a little different. Plus the cost of the Sonicaps for this part time speaker is a little hard to swallow. The RD-0194's alone will cost me more than what I paid for the CRS's.

I have yet to proceed. My plan (like yours) is to upgrade the crossovers with solen caps and see what happens. I will order the parts tomorrow and let you know how it turns out.

I'm with you on the price's, I would love to try the Sonicaps, but the cost to upgrade the crossover was going to cost more than what I paid for the speakers (with RDO-194's) and the stands :eek: . I need to save the money for my future SDA-SRS upgrade....:D

schwarcw · June 2006

Cool! Let us know how your project turns out. This stuff is fun!

Carl

DarqueKnight · November 2006

I'd like to thank F1nut for mentioning his 4.1TL CRS+ modification in a recent thread. It reminded me that I needed to go ahead and get this done. I just ordered the capacitors and RD0198-1 silk dome tweeters for the CRS+ speakers in my home office system. The new tweeters and capacitors should be here early next week. I'll report back after the mod is completed and burned in. My CRS+'s already have modded crossovers using AudioCap PPMF film capacitors and the original SL 2000 tweeters have been replaced with the RD0194-1 silk dome tweeters. In my case, all I needed to do was add a 5.8uF capacitor in paralled with the 2.7 ohm resistor in the tweeter circuit and install a RD0198-1 tweeter (SL 3000 replacement). The 12uF capacitor in the tweeter circuit is bypassed by (paralleled with) a 750pF silver mica capacitor to improve transient response. Polk's engineering department did not recommend replacing this capacitor as it is of very high quality and not subject to degradation over time (as are the stock electrolytics). I decided to replace it with a 0.001uF film capacitor just for grins.

F1nut wrote:

Awhile back I upgraded the crossovers in my CRS+'s using Sonicaps and Mills Wire-wound resistors along with the new RD0194-1 replacement tweeters. All in all a noticeable improvement over stock, but there was something that bothered me. The vocals usually sounded recessed or too far back compared to the rest and especially when compared to my 2.3TL's. Still, better than stock, but......

I modded each of the three pairs of CRS+'s I own and I did not notice any recessed vocals in any of them. However, I used different brands of capacitors: ICW and Solens for the black oak CRS+'s and AudioCaps for the two pairs re-veneered in teak. I also used the 12 watt Mills MRA-12 wire wound resistors rather than the MRA-5's that you used.

F1nut wrote:

While I was at it I decided to change out the 750pF Silver Mica in favor of a Sonicap .1uF [Gen II]cap.

I ordered a 0.001uF Gen I Sonicap. Did you actually use a 0.1uf or did you mean to say 0.001uf? The reason I ask is that a value of 0.1uF (0.1 x 10^-6) is 133.333 times greater than the original 750pf (750 x 10^-12) part. A 0.001uF capacitor (1 x 10^-9) is equivalent to 1000pF which is much closer to the 750pf part. Even if you did use the 0.1uF part, that is still miniscule compared to the 12uF capacitor it is paralleled with. Plus, you said you are happy with the sound so we can assume no harm done.

F1nut wrote:

SDA SRS 4.1TL parts list (for both boards)

Sonicap capacitor 5% or better tolerance
(2) .1uF Gen II (replaces the 750pF Silver Mica)
(2) 5.8uF

As stated previously, I ordered a 0.001uF Gen I Sonicap to replace the 750pF silver mica. The Gen I Sonicaps are supposed to be more "neutral" in sound compared to the "fuller", "more lush colored" sound of the Gen II's. Although, since we are talking about a extremely small value bypass capacitor, it probably would not make much audible difference whether a Gen I or Gen II Sonicap is used in this application.

When I went to the Soniccraft website, they were no longer carrying a 5.8uF Sonicap. They had 5.6uf and 6.2uF. I ordered the 5.6uF capacitor, which has a +/- tolerance of 5%, which means the true capacitance value can range from 5.32uF to 5.88uF. The Polk specified 5.8uF, 10% tolerance electrolytic capacitor has a capacitance value range of 5.22uF to 6.38uF. Of course, I could have used two capacitors in parallel to get the specified 5.8uF value, but I try to avoid splitting the signal between two capacitors if the circuit design specifies a single capacitor.

F1nut · November 2006

I used a .1uF for the bypass cap after discussing the matter with Jeff at Sonic Craft. His thinking was anything smaller was pointless. I should mention that after much listening to modded crossovers (film and foil caps) with bypass caps in use I have determined that they are not needed and in fact, cause unwanted artifacts. YMMV.

For future reference, Sonic Craft will custom value any of their Sonicap caps. When ordering just request the specific value needed. Of course, the 5.6uF should be fine as you noted.

I look forward to your impressions of the newly upgraded CRS+'s.

DarqueKnight · November 2006

Thanks for the tip on the custom cap values. I have dealt with Jeff before, and I asked to speak to him, but I was told he was not available. I spoke to someone named Elliott.

An engineer in Polk's design department (Chris) advised me to leave the silver mica bypass capacitor alone, but if I did decide to replace it, he advised against using polystyrene film capacitors because they are too "fast" and can cause the artifacts you mentioned.

F1nut · November 2006

Elliot mans the warehouse, fills and ships the orders, great guy.

Chris is wise man!

Check your PM box.

amulford · November 2006

I have to get started on mine. I would like to hear your impressions, also.

schwarcw · November 2006

I think Elliott is in Arkansas and Jeff is down is Texas. Check out the area codes for their numbers. Great people to do business with. As Jesse said they will get your exact value or spin you a custom. Elliott will check the caps with his meter.

Try it with and without the bypass. Use a pair of alligator clips to hold in the bypass cap. I'm curious to know if you hear a difference.

DarqueKnight · November 2006

When I did my SDA 1B crossover mod, after replacing the mylar caps with the correct value polypropylenes, I replaced the 750pF silver mica capacitors with 0.015uF polystyrene capacitors (remember, I was told by a Polk engineer not to use polystyrenes). I certainly heard a difference, and it was not a pleasant one. There was a little bit of hardness and harshness to the high frequencies. I quikly removed the polystyrenes and put 750pF polypropylene capacitors in their place. I could not hear a difference between the 750pF silver micas and the 750pF polypropylenes. I put the silver micas back in.

When I did my SDA 1C crossover mod, I replaced the 750pF silver mica capacitor with a MultiCap 1000pF (0.001uF)metallized polypropylene (PPMF-X) capacitor and didn't hear a difference with or without the bypass in place. But I left in the 1000pF MultiCap because I was tired and didn't feel like more soldering/desoldering.

When I did the crossover mods for my SDA SRS 1.2TL's, SDA SRS's and CRS+'s, I left the 750pF silver mica capacitors alone.

Since the 750pF silver micas were used to improve the transient response of the cheap mylar film capacitors that were used in SDA's, I am thinking that using a much higher quality modern polypropylene film capacitor in the main signal path would negate the need for a bypass of any type. Even knowing all this, for the CRS+ mod I will do next week, I still ordered polypropylene replacements for the silver mica caps.

F1nut · November 2006

DarqueKnight wrote:

Since the 750pF silver micas were used to improve the transient response of the cheap mylar film capacitors that were used in SDA's, I am thinking that using a much higher quality modern polypropylene film capacitor in the main signal path would negate the need for a bypass of any type.

That's the same conclusion I've come to.

Conradicles · August 2010

F1nut...great thread and thanks for the information.

Have there been any other changes/improvements for the SDA2BTL upgrade that I should consider before I place my order for the caps and resistors?

F1nut · August 2010

Conradicles wrote: »

Have there been any other changes/improvements for the SDA2BTL upgrade that I should consider before I place my order for the caps and resistors?

Yeah, get Larry's rings.

I almost forgot.....replace the poly with a .5 ohm Mills 12 watt resistor instead of replacing it with a jumper.

Hamatym · August 2010

The 2B's TL'd are an incredible! I still can not bellieve the improvement, and now just got word my 2.3TL's XO's are on their way back from Ben.....should be good times ahead!

F1nut · November 2010

Sal,

Do not order these,
(2) .1uF Gen II (replaces the 750pF Silver Mica)

Replace these with the 12 watt (MRA-12) version,
Mills Wire-wound 5 watt resistor 5% tolerance
(2) 2.7ohm MRA-5

F1nut · November 2010

That's it.

hoosier21 · November 2010

"combine the 30 & 10 to equal the needed 40uF as the largest cap from Sonicap is 30uF"

Is there a reason to not just but (2) 20's?

Conradicles · November 2010

hoosier21 wrote: »

"combine the 30 & 10 to equal the needed 40uF as the largest cap from Sonicap is 30uF"

Is there a reason to not just but (2) 20's?

I'm thinking they used the 30 and 10 combo due to the lack of room on the PCB, but 20 and 20 can work if you are crafty.

Face · November 2010

Sal, the .5ohm is optional. Given your taste in sound, I'd try it both ways.

Face · November 2010

If there's space, I would do 2 20's also, it's always better to split values in half.

F1nut · November 2010

Space is the problem. The crossover sits up tight in the corner and there is no extra room for a cap hanging off the side of the board. The 10uF tucks under the board perfectly.

Toolfan66 · March 2011

OK!! I thought I would get off my **** and get this going.

Well I dug out the crossovers on these to take a look,and I have the 2 piece crossovers in mine.

This is what I have.
One 12uf
Two 20uf (one on each board)
Two 130uf stacked on top of each other and the leads are tied together????
and one Poly switch and Mica..

What the hell is the two 130uf's????