Question about SRS2s and about capacitors

markamerica

1.) I was spending some time studying schematics as a learning exercise, and I looked at the SRS2 schematics(1986 version) but I could not make out one of the values for a capacitor on the dimensional array end. Specifically, there is a capacitor placed in parallel with the 130uF unit, and I cannot make out the number. Does anybody know what that is? It might be 65, but it might be 83, or something else entirely. If anybody has a pair and has modded them or knows with certainty, inquiring minds would like to know.

2.) I'm looking at modding/upgrading all my polk speakers. VR3 has lent me some assistance in figuring it out, so at least one of these projects will use Clarity Caps. I read an older thread where Darqueknight re-capped his, and he used Solen caps. I've heard varying things about many different capacitors, and I suppose some of it comes down to what you like, and how much your ears are tuned to notice a difference among them. I also saw some Erse capacitors. Anybody have any opinions on them? I'm sure there are more brands, but if you have experience with them, I'd sure like to hear about it. Particularly, if you've used more than one of these or other brands, I'd definitely like to get your impressions. I have a pair of SRS, SDA-2Bs, and 1.2TLs. All opinions are naturally welcome.

Thanks!

Schurkey

The early, Blade/blade version of the SRS 2 is electrically identical to the SDA 1B, except for one resistor in each HF crossover.

The capacitor in parallel with the 130uF is a 55uF, the total is 185uF, which I replaced with a pair of 91uF (182uF total) ERSE "Pulse X" film caps in each cabinet of my 1Bs.

My 1Bs got 1% tolerance Dayton caps in the HF crossovers, while the LF crossover board got the ERSE caps described above, along with 5% tolerance Dayton caps. I couldn't be happier. Sorry, I don't have decent photos of the HF circuit board.





I also installed ERSE steel-core 10mH inductors, de-wound to 9.6mH in the SDA circuit, replacing the higher-resistance air-core inductors supplied by Polk. The air-core inductors are still bolted in place, as they are the mounting point for the LF circuit boards, but they're no longer wired to the circuit board.

F1nut

Don't use Solens for anything other than the shunt circuit. I and many other prefer Sonicap due to their musicality.

VR3

I have modified many crossovers with people who have a set of SDAs with Sonicap/Mills and I have never had anyone like them over the Clarity Cap/Mundorf combination...

Obviously sound is a preference 100% but so far the track record for me has been consistent results.

With that said, obviously Sonicap and Mills offer a great product, no doubting that.

markamerica

Schurkey, You provided the answer to my question about the SRS2s because I was wondering, looking at them, if they didn't have almost the same set-up as the 1Bs. I noted the HF resistor difference, 2.0 for the 1Bs and 3.3(or 3.5?) for the SRS2s. My question about the SRS2s was based on what seemed like common equipment between them and the 1Bs. Thanks!

As for the inductors, I have a really dumb question: I have multimeters and do pretty well with those, but how do you measure inductance? For instance, if I were going to do as you had, buying a 10mH inductor and de-winding it to 9.6mH, how do you measure it? I've seen online calculators that permit me to figure out how many feet of xAWG magnet wire with an inside diameter of y and a height of z will produce inductance value a, but when I do a search on measuring inductance, I find all kinds of things involving function generators (I don't own one) and so on. Is there a simpler way?

As far as capacitors, I've read good and bad about all of them. In the real world, you say you're plenty happy with the Daytons and the Erses. Some have advised me not to mix brands. Not sure what to make of that.

Nice pictures. Thanks! Maybe I'll add some one day before too long.

Mark

markamerica

F1Nut,

Thanks for the tip. Of course, others feel differently about Solens, but I've heard a lot of good feedback regarding Sonicaps.

markamerica

VR3, thanks! I was thinking about the 2Bs as a project on which I'd like to spend fewer dollars. I expect that on the SRSs, I will go forward with Clarity Caps. I also have the 1.2TLs, and while I know where I could get some really spiffy looking crossovers for them right this minute on Ebay, I have to bite off only so much as my wallet can chew at one time.

As usual, between the farm and the day-job, I stay plenty busy, but I'm beginning to carve out larger hunks of time for musical endeavors(listening, not playing - I haven't the talent to make my own music.) I'm in an experimental mood, so be prepared for odd-seeming requests.

Thanks!

Mark

F1nut

Of course, others feel differently about Solens

There's either something wrong with their ears or they have never tried other caps. Harsh and grainy best describes their sound.

Schurkey

markamerica wrote: »

how do you measure inductance? For instance, if I were going to do as you had, buying a 10mH inductor and de-winding it to 9.6mH, how do you measure it?

I bought an LCR meter used, from eBay. I unwound, measured, unwound, measured, re-wound, measured...you get the idea.
L=inductance
C=capacitance
R=resistance
It's a BK Precision 878, and I think I paid ~$70 shipped to my door. Works nice for testing capacitors, too.

Easier Way: Tell the guys at ERSE that you want the 10mH inductor unwound to 9.6, and pay their modest fee for the modification. The e-mail they sent me almost two years ago said it was ten bucks each, twenty for the pair:

Remove about 5 turns to get 9.6mH. If you order 2 ESQ55-16-10000 we can dewind them to exactly 9.6mH for a $10 each fee.

In fact, I think I removed six turns.

I bought 16 gauge inductors (p/n ESQ55-16-10000) because the heavier-wire units were out-of-stock at the time. Looks like the 14-gauge version is now in stock. Mine are screwed to the bottom of the cabinet, with leads soldered to the circuit board and a snap-together "Weatherpack" connector to allow the inductor to be easily disconnected. I'm thinking that I put a similar connector on each of the original inductors, so I could pop out the passive radiator and swap inductors easily. I have yet to re-connect the original inductors.

Schurkey

F1nut wrote: »

Harsh and grainy best describes their sound.

Do they sound better, or worse than the original caps installed by Polk?

My expectation is that ANY modern film cap is going to sound MUCH better than the ancient and likely-degraded originals that are now far in excess of their expected service life.. Even "harsh and grainy" film caps are an improvement over the electrolytic caps on the circuit boards now.

Schurkey

I found a photo of my HF crossover after modification. I would not use the ceramic resistors again, the Mills resistors are more compact and fit the circuit board better. There is a third ceramic resistor soldered to the back side of the board--there was no room on this side!






Just to fuel the debate, I would suggest reducing the main input resistor on your HF circuit board from 3.x to somewhere between 1.5 and 2.0 ohms, increasing the level of the treble in relation to the mid- and bass level. My 1Bs with the original 2-ohm resistor or with the Mills 2 ohm resistor have been treble-shy. (It's the barely-visible brown item at the bottom of the board in my photo.)

F1nut

Schurkey wrote: »

Do they sound better, or worse than the original caps installed by Polk?

Going from the originals to Solens will result in harsh and grainy highs, so worse.

drumminman

I've used Sonicaps and Mills in 3 Xover rebuilds and been pleased with all three. Sonicap is the more widely used brand around here for Vintage Polks, though Clarity has been starting gain popularity as well.

From the descriptions I've read, the Sonicaps are a bit more lush and relaxed, the Clarity ESA's more analytical. Haven't had my ears on speakers using the Clarity so I can't speak from personal experience.

One other mod you'll want to consider is replacing the large inductor in the SDA circuit with something like a Solen 10AWG with a lower DCR. Improves the bass quite a bit.

markamerica

Thanks for the info! One of the things I'm learning about all of this is that everything's a trade-off. Schurkey, you suggest lowering the resistor value on the HF side to improve treble. What's the down-side? DrumminMan, you suggest a lower DCR inductor. Any downside? Schurkey, I appreciate the pictures. Seeing your mods/upgrades is helpful. You've given me a lot to think about already, and I'm sure there will be more.

markamerica

Another thing crosses my mind, speaking of resistors. I think all of the resistors on my stock crossovers are 5W. How important is the wattage value here? BTW, I meant to mention DrumminMan, I think the inductors I ordered through VR3 will have lower DCR than stock.

Schurkey, thanks for the tip on the meter. At $70, it's surely worth it. As far as inductors, I noted in one of Darqueknight's mod/upgrade posts where he played around with positioning the large inductor in various places in the cabinet. Is there any sort of consensus these days about where to best place it? Are there definite no-go locations?

Thanks!

Mark

VR3

I use DCR matched inductors. The lower DCR is usually recommended for the SDA inductor. Going to lower DCR inductors elsewhere can change the voicing of the speaker.

westmassguy

I've compared, side by side, Sonicap/Mills, Clarity ESA/Mundorf, and Clarity ESA/Mills. I, like many prefer the Sonicap/Mills combination. "Lush" is a great description, as is Musical. Clarity ESA are great Caps, but too "in your face" for my taste. I have found the ESAs can be tempered a bit with Mills Resistors, vs the Mundorf MOX.
As a rule, Inductors should be 90 degrees opposite on both planes, from any adjacent Inductor. This mitigates interference between the magnetic fields produced by each inductor.

[Deleted User]

I'm just curious, but has anyone ever taken two crossovers, one fully modified and the other stock and connected a signal generator to an amplifier then connect the amplifier to the crossover with appropriate loads? Then measure the outputs at a wide assortment of frequencies. In other words, with the same amplifier, test frequencies and resistive loads made a frequency response measurement of the crossover modified and unmodified?
If someone is interested in this, I can help.
Maybe measure before and after modifications?

headrott

Kenneth Swauger wrote: »

I'm just curious, but has anyone ever taken two crossovers, one fully modified and the other stock and connected a signal generator to an amplifier then connect the amplifier to the crossover with appropriate loads? Then measure the outputs at a wide assortment of frequencies. In other words, with the same amplifier, test frequencies and resistive loads made a frequency response measurement of the crossover modified and unmodified?
If someone is interested in this, I can help.
Maybe measure before and after modifications?

Can't remember if Ray (DK) has done it or not. But, it does seem like a measurement he would do. The results would be interesting to see and your suggestion is a great one Ken.

westmassguy

Kenneth Swauger wrote: »

I'm just curious, but has anyone ever taken two crossovers, one fully modified and the other stock and connected a signal generator to an amplifier then connect the amplifier to the crossover with appropriate loads? Then measure the outputs at a wide assortment of frequencies. In other words, with the same amplifier, test frequencies and resistive loads made a frequency response measurement of the crossover modified and unmodified?
If someone is interested in this, I can help.
Maybe measure before and after modifications?

Great Idea Ken. Would put a lot of arguments and assumptions to bed I think.

markamerica

Interesting, VR3. That's an aspect I was wondering about. Westmassguy, I had wondered about the physical arrangement of the inductors on the stock crossovers. You've answered that question as well.

As far as what my own tastes are, I actually like very precise, a bit "in your face" sound. I've read arguments going both ways, and I think this is where the whole subjective matter of "taste" comes in.

So we have opinions here on Daytons, Solens, Sonicap and Clarity Caps, but are there any opinions on Erse or others? I'm genuinely curious, although I realize a good deal will have to do with individual preferences. I wonder how much a given genre of music contributes to the decision. For instance, if one is listening to classical music or rock and roll or jazz, I'd imagine I might get different answers. So, if you were going to demo the SDA imaging effect for me, on a re-capped pair of speakers with your preferred caps, what piece of music would you choose if you could only pick one per genre? I've seen the recommendations list. I'm trying to see if I can find commonality.

Thanks!

Mark

markamerica

Ken,

That's a tremendously sensible idea. Of course, I don't probably have the instrumentation available for such comprehensive measurements. I'd sure like to try it, but I wouldn't know where to begin.

Thanks!

Mark

headrott

markamerica wrote: »

Interesting, VR3. That's an aspect I was wondering about. Westmassguy, I had wondered about the physical arrangement of the inductors on the stock crossovers. You've answered that question as well.

As far as what my own tastes are, I actually like very precise, a bit "in your face" sound. I've read arguments going both ways, and I think this is where the whole subjective matter of "taste" comes in.

So we have opinions here on Daytons, Solens, Sonicap and Clarity Caps, but are there any opinions on Erse or others? I'm genuinely curious, although I realize a good deal will have to do with individual preferences. I wonder how much a given genre of music contributes to the decision. For instance, if one is listening to classical music or rock and roll or jazz, I'd imagine I might get different answers. So, if you were going to demo the SDA imaging effect for me, on a re-capped pair of speakers with your preferred caps, what piece of music would you choose if you could only pick one per genre? I've seen the recommendations list. I'm trying to see if I can find commonality.

Thanks!

Mark

Mark, if you like more of the "in your face sound" (i.e. higher detail, resolution, transparency, imaging), the Clarity Cap ESA's are up your alley. While others recommended Mudorf Mox resistors and/or Mills, I would highly recommend some Duelund Cast resistors. IMO, they are great resistors and add to the afore mentioned audio aspects. They are expensive, but since you only have to replace them every 10+ years, they are worth every penny (IMO).

VR3

I have ran measurements per driver as part of my serial number program to test my crossovers. The circuits measure the same as far as frequency and impedance sweeps. I use it to compare the original circuit to the modified.

The way it sounds is greatly different however

westmassguy

markamerica wrote: »

Interesting, VR3. That's an aspect I was wondering about. Westmassguy, I had wondered about the physical arrangement of the inductors on the stock crossovers. You've answered that question as well.

As far as what my own tastes are, I actually like very precise, a bit "in your face" sound. I've read arguments going both ways, and I think this is where the whole subjective matter of "taste" comes in.

So we have opinions here on Daytons, Solens, Sonicap and Clarity Caps, but are there any opinions on Erse or others? I'm genuinely curious, although I realize a good deal will have to do with individual preferences. I wonder how much a given genre of music contributes to the decision. For instance, if one is listening to classical music or rock and roll or jazz, I'd imagine I might get different answers. So, if you were going to demo the SDA imaging effect for me, on a re-capped pair of speakers with your preferred caps, what piece of music would you choose if you could only pick one per genre? I've seen the recommendations list. I'm trying to see if I can find commonality.

Thanks!

Mark

If you like Mixed Celtic, I just got Enya's Only Time Collection, which is stunning. My 2ATLs with Sonicaps and Mills render each track lush, smooth as silk.
If that doesn't suit you, perhaps some Nickelback

markamerica

WestMassGuy, I must admit the only thing "Celtic" I ever really liked were people with names like "McHale," "Bird," "Havlicek," "Parish," "DeGregorio," "McAdoo" and "Archibald." (Among others.) I am not familiar with Nickleback.

Thanks!

Mark

westmassguy

Nickelback isn't quite Celtic, Canadian Rock Band. Big difference, but my 2As handle both types quite easily.

TennMan

Has anyone tried Olivia Newton John's "Soul Kiss" CD as an SDA demo? I think of it as Olivia's de-Greased CD. Although she is not my favorite singer the recording is exceptional. There are lots of crisp highs and bass that is tight with lots of impact. The sound come from everywhere including way outside the limits of the speakers yet it sounds open, airy and pinpoint precise. Right now it is the CD I would pull out to demonstrate what makes SDA speakers special.

Polkie2009

That is a excellent idea Kenneth , would be very interesting to see the results of the outcome. Gotta loveCeltic Woman, those gals are hot and can sing like angels.

westmassguy

Polkie2009 wrote: »

Love Celtic Woman, those gals are hot and can sing like angels.

Indeed

zingo

markamerica wrote: »

So we have opinions here on Daytons, Solens, Sonicap and Clarity Caps, but are there any opinions on Erse or others?

I've rebuilt SDAs with all of the above with good success, and just got my order of Erse caps for my SRS 2s. I will give feedback once they are installed, as they are a budget cap that looks high quality but I'm unsure of the sound quality. I do prefer the sound of the Mundorf MOX resistors over the Mills, but that's just my ear and preference.