Holy Crap those are expensive!

audiocr381ve

So, I was about to pull the trigger on the 16mH 14awg inductors for my SDA-2B's from Solen and then saw that god-awful price!

Wow. Are there alternatives? Links would be very helpful.

(I didn't bring up my last inductor thread because nobody was placing nice in it! )

Toolfan66

Try Erse SQ from PE sounds like they are really good as well and at $40 I want to put them up against the Solens..

audiocr381ve

TOOLFORLIFEFAN wrote: »

Try Erse SQ from PE sounds like they are really good as well and at $40 I want to put them up against the Solens..

PE is parts express right? If so, I couldn't find the right value. Should I just call in and get the 16mh 14awg? Or would you recommend a different size for the 2B's?

Toolfan66

The value they have is a little under but it looks like you will be OK with them..

audiocr381ve

These? http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=266-954

audiocr381ve

audiocr381ve wrote: »

These? http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=266-954

guys? Are those the wrong ones?

OldmanSRS

You have to choose between the 15 mH or the 17 mH Erse SQ. The 15mH will provide a little frequency boost above 100 Hz referenced to the stock 16 mH inductor and the 17 mH will reduce the bass frequencies above 100 Hz(tighten the lows). It's your decision. Of course you could also do what I did and buy the larger 17 mH inductor and unwind a few turns at a time until you get to the point where the bass sound perfect. If you go too far, wind a few turns back on. Keep the excess wire in a large loop so the air core inductance is not a factor. Once you are happy, cut the excess wire to length and make you final termination at the inductor.

Greg

inspiredsports

OldmanSRS wrote: »

You have to choose between the 15 mH or the 17 mH Erse SQ. The 15mH will provide a little frequency boost above 100 Hz referenced to the stock 16 mH inductor and the 17 mH will reduce the bass frequencies above 100 Hz(tighten the lows). It's your decision. Of course you could also do what I did and buy the larger 17 mH inductor and unwind a few turns at a time until you get to the point where the bass sound perfect. If you go too far, wind a few turns back on. Keep the excess wire in a large loop so the air core inductance is not a factor. Once you are happy, cut the excess wire to length and make you final termination at the inductor.

Greg

I'm glad you wrote this, as I just asked the question in another thread about how the move up or down in mH affects the bass response. I like your idea of unwinding to reduce the mH value of the 17. Do you remember how many winds you took off, and did you do it by ear or measure it with an LCR?

Last question, the Erse 17mh is 16 gauge and rated at 500w before saturation where their 14 gauge is rated at 600w. Have you ever played your Erse modded SRS's to the point you saturated the 16 gauge inductor, or did the speakers reach their limits first?

I've just emailed Erse to see if they will custom wind a 16mh 14 gauge, but I doubt they have the ability to do custom work.

audiocr381ve

OldmanSRS wrote: »

You have to choose between the 15 mH or the 17 mH Erse SQ. The 15mH will provide a little frequency boost above 100 Hz referenced to the stock 16 mH inductor and the 17 mH will reduce the bass frequencies above 100 Hz(tighten the lows). It's your decision. Of course you could also do what I did and buy the larger 17 mH inductor and unwind a few turns at a time until you get to the point where the bass sound perfect. If you go too far, wind a few turns back on. Keep the excess wire in a large loop so the air core inductance is not a factor. Once you are happy, cut the excess wire to length and make you final termination at the inductor.

Greg

That's great stuff. I'm looking for more punch, but I like the idea of unwinding until I get it right. It looks the 16awg is the only thing available from Parts Express. It's my understanding that I need the 14awg?

Outfitter03

inspiredsports wrote: »

Do you remember how many winds you took off, and did you do it by ear or measure it with an LCR?

Comparing the specifications looks like you could do it by weight also. 0.04 lbs. or 0.64 ounces of wire to remove. Given the two surrounding values of 15 mh and 18 mh appears to be a linear amount.

OldmanSRS

inspiredsports wrote: »

I like your idea of unwinding to reduce the mH value of the 17. Do you remember how many winds you took off, and did you do it by ear or measure it with an LCR?.

I removed 4 turns at a time, then measured the output of the XO to the SDA below 150 Hz. When the output was a little less than the stock 16.8 mH inductor and a little more than the fully wound 17 mH, I stopped. I ultimately removed 16 turns which for my ears produced the cleanest bass response (My impression of the stock 16.8 high DCR inductor has always been that bass response between 100 and 200 Hz was a little tubby). Read the thought process and see my measurements here: http://www.polkaudio.com/forums/showthread.php?123208-SDA-SRS1.2-with-Erse-SuperQ-inductor-modification

inspiredsports wrote: »

Last question, the Erse 17mh is 16 gauge and rated at 500w before saturation where their 14 gauge is rated at 600w. Have you ever played your Erse modded SRS's to the point you saturated the 16 gauge inductor, or did the speakers reach their limits first?

I've just emailed Erse to see if they will custom wind a 16mh 14 gauge, but I doubt they have the ability to do custom work.

I rarely play them over 200W peaks because in my room, it's just too damn loud. I find that 50W peaks produce very near live concert levels for the type of music I listen too. There is one song on the old Bach Busters CD, Track-8, that has a quick bass peak that I've since played near the limits of the TFM-35 (500W at 4 ohms) and I heard no distortion. That peak almost knocks the pictures off the walls.

The unexpected benefit of the inductor swap was how the mids cleared up. I was going for more low bass control and tactile feel and I got that but the improved midrange was a complete surprise. The muddy lower mid/upper bass was attenuated with by the inductor and the lower DCR provides improved cone control and damping. The mids come through much cleaner. I also noted a reduction in "phasiness" in the SDA soundstage on some very wide recordings.

inspiredsports

Outfitter03 wrote: »

Comparing the specifications looks like you could do it by weight also. 0.04 lbs. or 0.64 ounces of wire to remove. Given the two surrounding values of 15 mh and 18 mh appears to be a linear amount.

From the erseaudio.com site for their 16 gauge Super Q's:

10 mH = 1.38 lbs.

12 mH = 1.47 lbs.

13 mH = 1.51 lbs

14 mH = 1.57 lbs

15 mH = 1.60 lbs.

16 mH = not produced

17 mH = 1.68 lbs.

18 mH = 1.72 lbs.

19 mH = not produced

20 mH = 1.76 lbs.

Inductors are made to the nearest wind (no fractions of a wind), which may or may not be spot on at a 1.0 mH increment and might explain why the 19 mh would extrapolate to be 1.76, same as a 20

inspiredsports

OldmanSRS wrote: »

. . . I removed 4 turns at a time, then measured the output of the XO to the SDA below 150 Hz. When the output was a little less than the stock 16.8 mH inductor and a little more than the fully wound 17 mH, I stopped. I ultimately removed 16 turns which for my ears produced the cleanest bass response (My impression of the stock 16.8 high DCR inductor has always been that bass response between 100 and 200 Hz was a little tubby). Read the thought process and see my measurements here: http://www.polkaudio.com/forums/showthread.php?123208-SDA-SRS1.2-with-Erse-SuperQ-inductor-modification

Good thread! I noticed you wrote that you kept the wire you snipped off in the event you wanted to add it back on in the future. Can you just solder the ends together and wind it back onto the core?

Toolfan66

I would think so, if you can raise the output by just using a steel bolt to mount it I would think soldering a piece in would be fine. But what do I know I'm still a novice in this fantastic hobby.. :-)

inspiredsports

Concerning the Erse Q line (laminated steel cores):

You don't need 14 gauge, it just has a higher power handling capability (600W). Everyone seems to feel the 500W capable 16 gauge is fine, even in an SRS, so it would be more than fine in a 2B with lower power handling capability.

You also need to understand that bigger gauge wire (lower is bigger) has less DC resistance (DCR). Lower DCR inductors will lower the nominal impedance of the speaker system. 2B's will drop from around 6 ohms to perhaps 4 or 4.5 even with the Erse 16 gauge.

I can't remember what amp you are using, but it might make a difference if your amp isn't comfortable driving into a 2-4 ohm load.

##################################

Air-Core is a different story (Solens in your initial post) as much more wire is used (adds resistance) and they don't drop the impedance like the Erse steel cores.

Toolfan66

Oh and yes this is a great thread by AC, he has two of them going and both have turned out very informitive..

Toolfan66

Well the stock inductors have been fine for over 20 years till all the upgrading bug started before I joined here. It is funny how when one upgrade starts it spreads like wild fire around here like a bunch of crackheads looking for a new high!! LOL!!

My self included.. I'm going to guess my speakers hit the 2ohm now and then with the Solen inductors, I will have to revisit DK's thread in his findings as I don't remember of the top of my head at the moment..

inspiredsports wrote: »

You don't need 14 gauge, it just has a higher power handling capability (600W). Everyone seems to feel the 500W capable 16 gauge is fine, even in an SRS, so it would be more than fine in a 2B with lower power handling capability.

You also need to understand that bigger gauge wire (lower is bigger) has less DC resistance (DCR). Lower DCR inductors will lower the nominal impedance of the speaker system. 2B's will drop from around 6 ohms to perhaps 4 or 4.5.

I can't remember what amp you are using, but it might make a difference.

inspiredsports

TOOLFORLIFEFAN wrote: »

Well the stock inductors have been fine for over 20 years till all the upgrading bug started before I joined here. It is funny how when one upgrade starts it spreads like wild fire around here like a bunch of crackheads looking for a new high!! LOL!!

My self included.. I'm going to guess my speakers hit the 2ohm now and then with the Solen inductors, I will have to revisit DK's thread in his findings as I don't remember of the top of my head at the moment..

The way I read it, the most important data in DK's thread was the Adobe Acrobat pdf written by Matt and Stu. They came right out and said higher DCR inductors (air core) were used because most amps in the mid-eighties were uncomfortable driving less than 6-ohm loads.

The compromise made was to use air-core inductors which add DCR, but lowers/slows/muddies bass response. The approx 2 ohms of resistance the air-core inductor adds sucks up and stores or gives off as heat energy is wattage that coud be delivering/controlling bass.

I'm guessing if designed today (as in many of their modern designs), SDA's would have Erse Super Q-style laminated steel core inductors.

Stew

audiocr381ve wrote: »

These? http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=266-954

Those are the one I used in my 2B-TL's. I just screwed them to the floor of the cabinets, added spades to the leads, unplugged the leads from the old inductors and plugged in the new ones. Easy! I'm very happy with the results.

audiocr381ve

Stew wrote: »

Those are the one I used in my 2B-TL's. I just screwed them to the floor of the cabinets, added spades to the leads, unplugged the leads from the old inductors and plugged in the new ones. Easy! I'm very happy with the results.

Awesome stuff guys! I ordered the 17mh 16awg Erse Super Q. Should be here next week.

Stew, you left the original inductor inside? When you screwed the new inductor down, what kind of screw did you use? Did it make it through the bottom of the cab?

audiocr381ve

OldmanSRS wrote: »

I removed 4 turns at a time, then measured the output of the XO to the SDA below 150 Hz. When the output was a little less than the stock 16.8 mH inductor and a little more than the fully wound 17 mH, I stopped. I ultimately removed 16 turns which for my ears produced the cleanest bass response (My impression of the stock 16.8 high DCR inductor has always been that bass response between 100 and 200 Hz was a little tubby). Read the thought process and see my measurements here: http://www.polkaudio.com/forums/showthread.php?123208-SDA-SRS1.2-with-Erse-SuperQ-inductor-modification



I rarely play them over 200W peaks because in my room, it's just too damn loud. I find that 50W peaks produce very near live concert levels for the type of music I listen too. There is one song on the old Bach Busters CD, Track-8, that has a quick bass peak that I've since played near the limits of the TFM-35 (500W at 4 ohms) and I heard no distortion. That peak almost knocks the pictures off the walls.

The unexpected benefit of the inductor swap was how the mids cleared up. I was going for more low bass control and tactile feel and I got that but the improved midrange was a complete surprise. The muddy lower mid/upper bass was attenuated with by the inductor and the lower DCR provides improved cone control and damping. The mids come through much cleaner. I also noted a reduction in "phasiness" in the SDA soundstage on some very wide recordings.

I'm so excited about this! You'll have to walk me through how to unwind the thing. I don't have any measurement tools so I'm going to have to rely on my ears for this.

Stew

It's been several years ago and I don't remember the specifics. I just grabbed some wood screws from my extra fasteners bucket. I would measure the thickness of the cabinet and pick something slightly shorter so they don't go through.

audiocr381ve

Stew wrote: »

It's been several years ago and I don't remember the specifics. I just grabbed some wood screws from my extra fasteners bucket. I would measure the thickness of the cabinet and pick something slightly shorter so they don't go through.

That's great. Do you remember if you left the original inductors inside?

drumminman

TOOLFORLIFEFAN wrote: »

Well the stock inductors have been fine for over 20 years till all the upgrading bug started before I joined here. It is funny how when one upgrade starts it spreads like wild fire around here like a bunch of crackheads looking for a new high!! LOL!!

My self included.. I'm going to guess my speakers hit the 2ohm now and then with the Solen inductors, I will have to revisit DK's thread in his findings as I don't remember of the top of my head at the moment..

IIRC DK (or someone) measured impedance with the new Solen air core 16 mH 10 awg inductors as around 3.1-3.4 ohms. Having an amp stable to at least 2 ohms would give that extra margin of safety.

OldmanSRS

audiocr381ve wrote: »

I'm so excited about this! You'll have to walk me through how to unwind the thing. I don't have any measurement tools so I'm going to have to rely on my ears for this.

Connect it and listen to various recordings. My bet is it will sound thin and less warm. If so simply remove the black tape and unwind 4-5 turns, reinstall and listen again. You can connect the original inductor for a comparison. Continue to remove a few turns until you get the sound you want. If you go too far, tightly wind a few turns back on. Keep the excess wire in a 1' diameter loop so it's inductance is negligible. I placed the inductor on the floor of the SRS on a piece of foam during this process.

I find it hard to mod just one speaker and compare to the other so I did the mods equally to both and tested as a system.

inspiredsports

drumminman wrote: »

IIRC DK (or someone) measured impedance with the new Solen air core 16 mH 10 awg inductors as around 3.1-3.4 ohms. Having an amp stable to at least 2 ohms would give that extra margin of safety.

I think the original thin 18 gauge inductors Polk used were around 2-3 ohms. I can't imagine huge 10 gauge could have that much resistance. They're probably under 1.

It's these new LOWER DCR inductors that are under 1 ohm that lower system DCR creating difficult loads for some amps.

drumminman

inspiredsports wrote: »

I think the original thin 18 gauge inductors Polk used were around 2-3 ohms. I can't imagine huge 10 gauge could have that much resistance. They're probably under 1.

It's these new LOWER DCR inductors that are under 1 ohm that lower system DCR creating difficult loads for some amps.

Yeah, I think I measured mine before I installed them and it was like 0.6. I deliberated a bit before I went that route, and checked my amp specs to be sure i wouldn't have issues. The first couple of sessions after installation I kept feeling the amp to see if it was overheating. It was a little warmer than before the inductors, but not much. BTW, it's rated stable to 2 ohms so there's a bit of safety margin.

sda2mike

great post! i look forward to reading your impressions

mike

audiocr381ve

sda2mike wrote: »

great post! i look forward to reading your impressions

mike

I'll be sure to chime in!

heiney9

audiocr381ve wrote: »

I'll be sure to chime in!

Wait more than an hour after they are completed :cheesygrin:

audiocr381ve

heiney9 wrote: »

Wait more than an hour after they are completed :cheesygrin: