SDA SRS1.2 with Erse SuperQ inductor modification

TennMan

South Dakota Po wrote: »

I also have Reatta and Polks. Only the top 60 Buick dealers in the country got one of these.

Absolutely beautiful Select Sixty. If you haven't done so already stop by my website Reatta Owners Journal (www.reattaowner.com) sometime. Sign up for the forum and talk Reattas with us. We'll make you feel at home!

OldmanSRS

I've been away for a while so it's nice to see this thread reactivated and discussing cars I have a couple new pics to show you guys.



And the TR6

TennMan

Wow! Beautiful cars. Were the two photos taken at the Dragon? Looks like one of it's curves.

I see a 16 on the old tag on the TR6. Is it a Roane County car?

TennMan

To get back on topic my PE order for the 17mh 16awg Super Q inductors should be arriving early this week. I will post my comments about them once they are installed.

OldmanSRS

TennMan wrote: »

I see a 16 on the old tag on the TR6. Is it a Roane County car?

Yes, both photos were taken on the Dragon in October/November a weekend apart. It was mid in the 30's both days. The plate is a "retired" period (1972-1973)TN plate that I designated as mine through the DMV. I have the original OH plates, the 20 day OH temporary paper plate, and a folder of original documents including the window sticker and bill of sale shown here.





How about a 32 year old state inspection sticker on the bumper...


Looking forward to hearing your speakers sometime. You will like the inductor mod.

TennMan

After spending some time listening to my 2BTLs with the Erse Super Q (17mh 16awg) inductors installed I can highly recommend them. They made a significant difference in the sound of my speakers. Not only did this mod improve the bass, it also seemed to make the mid range much more open sounding. Almost as if a curtain has been pulled back so you can clearly hear the speakers the way they were meant to sound. The highs are crisp and clean. Air core inductors might be better but these inductors (laminated steel core) are really a good bang for the buck. I think they should be installed at the same time anyone is doing the TL upgrade to a pair of 2Bs. The RDO-198 tweeters and the Erse Super Q inductors seem to compliment each other and make the 2BTLs sound much more balanced.

Getting the inductors right without a meter didn't work too well for me. After reading all the posts here on Club Polk about using these inductors I unwound 15 turns of wire off when I first received them thinking they would be close to where I needed to be (16mh). I didn't cut off the excess wire. Then I installed them and tested them out. At 15 turns unwound they just didn't sound right to me. The bass, although pretty deep, was weak to my ears and the SDA effect was not good. Thinking more was better I unwound another 5 turns off the inductors bringing the total to 20 turns unwound. That improved the SDA but the bass still just seemed wrong. At that point I realized I shouldn't continue flying blind so I ordered a meter capable of measuring LCR.

Once I had the new meter in hand I checked my stock inductors and they measured close to 16mh as specified in the schematic. That told me the meter was working correctly. Then I checked the Erse inductors. To my surprise the LCR was just slightly over 14mh for both inductors so I began the job of winding turns back on the inductors. Let me tell you. That is hard on your hands if you keep the windings straight and tight. By the time I added enough turns back on both inductors to reach 15mh my hands were aching and cramping. At that point I decided it was time to do some testing to see if I was going the right direction to get the sound I was looking for. At 15mh the SDA was back to normal but the upper bass was a little too strong and the vocals were a little too much "in your face" for my liking.

Then I pulled the inductors back out and wound enough turns back on to get me up to 16mh (as specified in the schematic) and installed again for more listening tests. At 16mh the SDA was still good but I felt I had lost a too much punch in the upper bass that was excessive with the inductors set at 15mh. With that in mind I removed the inductors one more time and adjusted the LCR again. This time to 15.5mh (+- .05mh) and reinstalled. I know second guessing Polk might not be the best thing to do but for me that is where I feel they sound the best. I would agree that me thinking .5mh made a difference one way or the other might be psychological but hey, getting speakers to sound the way you like is what modding them is all about. At this point I have no intention of making more changes.

Thanks to all the forum members who wrote articles about using these inductors. Special thanks to westmassguy and OldmanSRS for convincing me to do this mod. You guys have helped me a lot with these speakers.

Here are a few things I learned from installing these steel core inductors.

1.) In my experience it would be hard to get the LCR right without a meter. It is a hit or miss proposition but it could be done.
2.) You need a good amplifier to drive your speakers with these inductors installed. The DCR of my 2bTLs dropped to 3 ohms, which was expected.
3.) Unwinding turns from the inductor is not linear. Each turn removed from the inductor doesn't change the LCR by the same amount across the inductor.
3.) You shouldn't use the meter to determine when your speakers sound the best. That is what ears are for.

txcoastal1

Oldman awesome rides

Tennman nice right up on mod...nice detail as it seems you can easily screw up the sound

Congrats bud

Happy Holidays

TennMan

txcoastal1 wrote: »

Oldman awesome rides

Tennman nice right up on mod...nice detail as it seems you can easily screw up the sound

Congrats bud

Happy Holidays

Yeah, but the good news is nothing you screw up with this mod is permanent. It can be easily reversed by either plugging in your old stock inductors or making adjustments by adding or removing turns of wire with the aid of a meter capable of measuring LCR. I like things that are adjustable. It gives you the option of dialing in the sound to your liking.

westmassguy

Very nice write up grasshopper. Now we just need to make you some custom spikes for your unique height requirements, and you'll be all set.

Phasewolf

The more inductance you have the less the SDA speakers can get into the upper bass and lower mid range. As you lower the inductance the driver is allowed to play at higher and higher ranges which it sounds like you found out for yourself.

Remember the stock inductor has a metal bolt that holds it in place and that will raise it value. When I measured the bolt added around 1mh so the 16mh inductor would of been closer to 17.

If I recall the stock 2.3 called for a 16mh and the 2.3TL had a 15mh when you add the bolt it wild then be at the 16mh as they wanted.

westmassguy

Phasewolf wrote: »

The more inductance you have the less the SDA speakers can get into the upper bass and lower mid range. As you lower the inductance the driver is allowed to play at higher and higher ranges which it sounds like you found out for yourself.

Remember the stock inductor has a metal bolt that holds it in place and that will raise it value. When I measured the bolt added around 1mh so the 16mh inductor would of been closer to 17.

If I recall the stock 2.3 called for a 16mh and the 2.3TL had a 15mh when you add the bolt it wild then be at the 16mh as they wanted.

Very true, which is why I never use any ferrous metal standoffs, or fasteners when adding additional riser boards during crossover upgrades. Any ferrous metal in close proximity to any type of inductor will alter its magnetic field, and it's resultant mh value. It can also theoretically add distortion components when the field is interrupted.

TennMan

westmassguy wrote: »

Very true, which is why I never use any ferrous metal standoffs, or fasteners when adding additional riser boards during crossover upgrades. Any ferrous metal in close proximity to any type of inductor will alter its magnetic field, and it's resultant mh value. It can also theoretically add distortion components when the field is interrupted.

Hmmmm, maybe I didn't do a test right because I had the inductor set at 15.5mh on the workbench. Then did a listening test to see how it would sound. Then I mounted it on the old stock inductor [photo below] and it still tested 15.5mh. Once I had the crossover bolted to the cabinet I tested again and got 15.5mh. Plugged it into the crossover and I have been listening to it that way ever since. Do you think the way I have it mounted is causing a problem I haven't detected?

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westmassguy

Ronnie, you should be fine, however, I believe I told you to mount it directly to the back wall with a couple 5/8" screws

TennMan

westmassguy wrote: »

Ronnie, you should be fine, however, I believe I told you to mount it directly to the back wall with a couple 5/8" screws

You did indeed. I just like the idea of pulling it all out as a unit if it doesn't hurt anything. I like simplicity.

TennMan

westmassguy wrote: »

Very nice write up grasshopper. Now we just need to make you some custom spikes for your unique height requirements, and you'll be all set.

Thanks! I have an idea about how to remedy the height limitation problem. I have been kicking around the idea of building a speaker Polk skipped over. The SRS 1TL. It would be a little brother to the SDA SRS2 (right photo). It would use 2BTL crossovers, MWs, Tweeters and passive radiator. The cabinet would be the same width as a CRS+ and have the same MW and tweeter spacing. The cabinet would be shorter by the proper amount to produce the same internal volume as the 2B cabinet. The shorter cabinet would give me room for spikes on the bottom. I think it would be an interesting project. Now all I need is some MDF, cloth and a lot of time. :biggrin:

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westmassguy

TennMan wrote: »

Thanks! I have an idea about how to remedy the height limitation problem. I have been kicking around the idea of building a speaker Polk skipped over. The SRS 1TL. It would be a little brother to the SDA SRS2 (right photo). It would use 2BTL crossovers, MWs, Tweeters and passive radiator. The cabinet would be the same width as a CRS+ and have the same MW and tweeter spacing. The cabinet would be shorter by the proper amount to produce the same internal volume as the 2B cabinet. The shorter cabinet would give me room for spikes on the bottom. I think it would be an interesting project. Now all I need is some MDF, cloth and a lot of time. :biggrin:

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You just love your Franken-Polks.
I've been tossing around an idea on how to do yours, I'd even karma it for you.

TennMan

westmassguy wrote: »

You just love your Franken-Polks.
I've been tossing around an idea on how to do yours, I'd even karma it for you.

Are you talking about building the Franken-Polks or designing some spikes? LOL.

westmassguy

TennMan wrote: »

Are you talking about building the Franken-Polks or designing some spikes? LOL.

No special spikes for your set.

Mr. Bubbles

westmassguy wrote: »

No special spikes for your set.

I wonder if you meant "No; special spikes for your set" instead.

It makes me think of a teacher once that tried to teach me how important punctuation is. ( I still don't get it most of the time) Due to his explanation , it does stand out to me sometimes. His explanation is as follows.

The following sentence can have two drastically different meanings but using or omitting a coma.

I was helping my uncle Jack, off his horse. Or....
I was helping my uncle Jack off his horse.

westmassguy

Mr. Bubbles wrote: »

I wonder if you meant "No; special spikes for your set" instead.

It makes me think of a teacher once that tried to teach me how important punctuation is. ( I still don't get it most of the time) Due to his explanation , it does stand out to me sometimes. His explanation is as follows.

The following sentence can have two drastically different meanings but using or omitting a coma.

I was helping my uncle Jack, off his horse. Or....
I was helping my uncle Jack off his horse.

Ronnie knows what I was talking about, but I see your point. I'm usually pretty good with punctuation.
That's a great example, but would be considered sexual harassment today.

Mr. Bubbles

Man, I didn't think about it until now. i hope you didn't think i meant anything bad by my comment. I just read your post and was unsure (though it wasn't really meant for me) and it made me think of that scenario with my teacher way back when. Of course, with that example, a good many things make me think of it. But I am still horrible with punctuation most of the time. Anyway, I hope you didn't take it bad as it was not meant that way. Have a great Christmas to you and all others on here.

westmassguy

Mr. Bubbles wrote: »

Man, I didn't think about it until now. i hope you didn't think i meant anything bad by my comment. I just read your post and was unsure (though it wasn't really meant for me) and it made me think of that scenario with my teacher way back when. Of course, with that example, a good many things make me think of it. But I am still horrible with punctuation most of the time. Anyway, I hope you didn't take it bad as it was not meant that way. Have a great Christmas to you and all others on here.

Mr Bubbles, chill. No offense taking at all, was just commenting on when I went to school vs the conditions that abound today in or schools. Merry Christmas to you as well.

westmassguy

Ronnie, this is my Idea for your spike/height problem

TennMan

David, thanks for the posting drawing. It is an excellent idea. However, As you can see in the photo below, I'm very limited in space between the bottom of the cabinet door and the top of the speaker. Just raising the speaker up enough to put the thickness of a nickel under the spike would cause the top of the speaker to hit the door.

One option that might work is to mount a bracket outboard of the speaker as shown in the bottom photo. With that type of bracket it would be possible to adjust the spike up high enough that the spike would not touch the hardwood but when a thick disk is inserted under the spike the speaker would be raised slightly off the floor and the weight would be placed on the disk. The drawback to that is I don't think it would look good and I don't want to drill holes in the wood base of cabinets. I've not given up on this and I'm not in a hurry to get it done. Thanks again for your input. I appreciate it.

Toolfan66

TennMan wrote: »

David, thanks for the posting drawing. It is an excellent idea. However, As you can see in the photo below, I'm very limited in space between the bottom of the cabinet door and the top of the speaker. Just raising the speaker up enough to put the thickness of a nickel under the spike would cause the top of the speaker to hit the door.

One option that might work is to mount a bracket outboard of the speaker as shown in the bottom photo. With that type of bracket it would be possible to adjust the spike up high enough that the spike would not touch the hardwood but when a thick disk is inserted under the spike the speaker would be raised slightly off the floor and the weight would be placed on the disk. The drawback to that is I don't think it would look good and I don't want to drill holes in the wood base of cabinets. I've not given up on this and I'm not in a hurry to get it done. Thanks again for your input. I appreciate it.

Love the idea, except I would look into lag bolts not wood screws, I don't think the weight of the speakers will hold up to wood screws..

TennMan

Toolfan66 wrote: »

Love the idea, except I would look into lag bolts not wood screws, I don't think the weight of the speakers will hold up to wood screws..

Yeah, the brackets would need to be mounted securely to support the speakers. I think 80 pounds is the weight of the 2Bs.

Toolfan66

Why not look at the bracket going underneath the speaker form one side to the other, and screw it in underneath the speaker?

That way you only need two brackets per speaker, and you wouldn't have to put holes in the side of the end cap, and it would hold the weight of the speaker..

TennMan

Toolfan66 wrote: »

Why not look at the bracket going underneath the speaker form one side to the other, and screw it in underneath the speaker?

That way you only need two brackets per speaker, and you wouldn't have to put holes in the side of the end cap, and it would hold the weight of the speaker..

That's a great idea and I did consider it in the beginning. However, I decide if the bracket was thick enough to be rigid and not flex on the ends where the spikes would be located, they would be so thick that the speaker would be high enough to hit the bottom of the doors. The speakers have to stay down as low as they are now. Two quarters stacked will not go under them at the height they are now.

You can't tell how close it is in the photo below but maybe you can get an idea about what I'm dealing with. Had I owned the 2Bs when I built the house I would have raised the built in cabinets higher. That isn't an option now.

westmassguy

TennMan wrote: »

David, thanks for the posting drawing. It is an excellent idea. However, As you can see in the photo below, I'm very limited in space between the bottom of the cabinet door and the top of the speaker. Just raising the speaker up enough to put the thickness of a nickel under the spike would cause the top of the speaker to hit the door.

One option that might work is to mount a bracket outboard of the speaker as shown in the bottom photo. With that type of bracket it would be possible to adjust the spike up high enough that the spike would not touch the hardwood but when a thick disk is inserted under the spike the speaker would be raised slightly off the floor and the weight would be placed on the disk. The drawback to that is I don't think it would look good and I don't want to drill holes in the wood base of cabinets. I've not given up on this and I'm not in a hurry to get it done. Thanks again for your input. I appreciate it.

Ronnie, your 2Bs are sitting on glides now aren't they? These would take the place of those.

westmassguy

Toolfan66 wrote: »

Love the idea, except I would look into lag bolts not wood screws, I don't think the weight of the speakers will hold up to wood screws..

What wood screws? They're 1/4-20 hex head machine bolts, sharpened to a point, then hardened. Four of them will easily hold up a 2B. They're threaded down through the Hurricane nuts from inside, adjusted as needed, then locked with the clinch nut.