The AI-1 Dreadnought Project Pt.1

[DarqueKnight]

Looking at the specs of the toroid the inductance seems like it would affect the hf. I am guessing that the low DCR (.3ohs roughly)of the windings helps offset the filtering?

I recall that Polk redesigned the SDA circuit and limited it to a specific band of frequencies below the high frequency crossover point. I don't remember what the SDA signal frequency range is. It's in my notes somewhere.

Looking at the way you wired it I am thinking that if the toroid was a slight step up, or down you may not be able to wire it for gain, or minus of the cancellation signal? I did however notice that there are 4 completely separate windings so I am thinking it may work. I am also rethinking my statement on the center stage collapsing. The stereo drivers would still be receiving full signal.
Any thoughts?

Try it and see.:)

[ben62670]

I recall that Polk redesigned the SDA circuit and limited it to a specific band of frequencies below the high frequency crossover point. I don't remember what the SDA signal frequency range is. It's in my notes somewhere.

The SDA signal ranges up to 2-2.5khz leaving out the first gen of coarse.

[DarqueKnight]

I was looking for a better vibration damping material than the two neoprene rubber pads supplied with the Avel-Lindberg transformer. F1nut suggested I try Dynamat Extreme and offered to send me some. Thanks F1.

Dynamat Extreme panels were applied to all six sides of the Dreadnought's case, to the top of the transformer retaining ring, and between the transformer and the wood brace block. The brace block is there to provide additional support because the transformer enclosure rests on that side (see figure 23). Per the manufacturer's advice, the transformer's retaining bolt was hand tightened to avoid the possibility of over tightening. Overtightened with a wrench could damage the coil insulation and cause a short.









The Dynamat Xtreme didn't make a big difference, but the difference wasn't subtle either. I'd compare it to tightening down the very last 1/4 turn on an already tight bolt:

1. The pace of the music was a little faster.
2. Bass was a little tighter, heavier, and more defined.

The larger Dynamat pieces were cut on the underside of a small 2' x 2' wooden drafting table. A drafting t-square was used for a guide and cuts were made with a box cutter. Smaller pieces were cut with a very sharp pair of scissors.

[F1nut]

Looking good!

[DarqueKnight]

My Polk original AI-1 arrived today. I listened to it for 30 seconds then had to apply the baked potato tweak. I managed to hang in for a little over an hour before I had to go back to the Dreadnought.

I just wanted one for my treasure chest of SDA artifacts...and to have one for comparison purposes when I decide to mass produce the Dreadnought.






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Calm down. Don't get excited. He's just kidding about mass producing that thing.

[hearingimpared]

Calm down. Don't get excited. He's just kidding about mass producing that thing.

I just cussed you out Doc!:p

[george daniel]

Transformer shipped on Tuesday,,, should have it in operation by next weekend if all goes as planned,, will be driving 2.3 tl's with mono's,,hopefully.Thanks again DK, for the informative post.

[Face]

I just cussed you out Doc!:p

I've seen your crossover work, I can't see you having a problem building a Dreadnought.

[hearingimpared]

Thanks Bro but Ray's work is perfect.

[m00npie]

So Face, are you going to build me one? I'll buy you a liter of cola :D

[DarqueKnight]

If he'll build you one for a liter of cola, I'll give him two liters to build me one too.:)

[hearingimpared]

What cheapskates, I'll buy him a couple of cases.

[Face]

So Face, are you going to build me one? I'll buy you a liter of cola :D

How about a few litres of Guinness? :D

[m00npie]

How about a few litres of Guinness? :D

Sold! I just have to get the amps so it would be useful.

[MillerLiteScott]

Here is my latest incarnation of the Avel Isolation Transformer. I am holding out for scraps of 20 oz. copper for the "final" stage.

A few pictures.

[F1nut]

Eh, I've got some catching up to do.

[ben62670]

Here is my latest incarnation of the Avel Isolation Transformer. I am holding out for scraps of 20 oz. copper for the "final" stage.

A few pictures.

Looks real nice;) Good work:)

Eh, I've got some catching up to do.

I have a lot of catching up to do:(

[nspindel]

I'm just seeing this for the first time, and once again am humbled by DK's work! One question I have: if this offers the sonic improvements over using the grounding strap and a straight sda connection by isolating the sda signal from the amp's ground, is there any reason why this application should be limited to non-common ground amps? Or would using a setup like this be applicable in all sda installations (capable of using the AI-1), even with common ground amps where the normal sda connection works just fine?

[DarqueKnight]

...if this offers the sonic improvements over using the grounding strap and a straight sda connection by isolating the sda signal from the amp's ground, is there any reason why this application should be limited to non-common ground amps?

People have asked about using an AI-1 with a common ground amp, but I don't recall reading a report from someone who did it. This is on my long list of things to try, but I haven't gotten to it yet.

I don't know of a reason why an AI-1 couldn't be used with a common ground amp.

[nspindel]

I'm just wondering if a steroidal AI-1 assembly like you've built would offer sonic improvements in all applications, regardless of whether the amp is common ground or not.

[hearingimpared]

I'm just wondering if a steroidal AI-1 assembly like you've built would offer sonic improvements in all applications, regardless of whether the amp is common ground or not.

STEROIDAL . . . that's a good one.:D

[nspindel]

I was going to say terroidal, but steroidal just sounded so much better :)

[DarqueKnight]

I'm just wondering if a steroidal AI-1 assembly like you've built would offer sonic improvements in all applications, regardless of whether the amp is common ground or not.

Maybe. Maybe not. I don't know. I would think that taking the SDA signal out of the amplifier's ground path is a good thing, even for a common ground amp.

STEROIDAL . . . that's a good one.:D

Compared to the tiny stock AI-1, the Dreadnought is steroidal.;)

[nspindel]

DarqueNight, any links on where to get the transformer? I asked PartsExpress for a price on the Y236906 since they sell Avel, but it's a special order for them and they're quoting $130.08 plus shipping. Also, do you have a link to where the enclosure can be purchased?

Thanks...

[george daniel]

Avel Lindberg direct,, just call em and they'll take it from there

I got my case from parts express,,, matter of fact,, I'll be putting mine up FS soon,,as I don't need it,, good luck.

[DarqueKnight]

DarqueNight, any links on where to get the transformer? I asked PartsExpress for a price on the Y236906 since they sell Avel, but it's a special order for them and they're quoting $130.08 plus shipping. Also, do you have a link to where the enclosure can be purchased?

Thanks...

The transformer was ordered directly from Avel-Lindberg (www.avellindberg.com). The enclosure was ordered form Par Metal, Inc. (www.par-metal.com).

[nspindel]

Thanks! Been talking to George offline though, I may be grabbing his whole assembly.

[ESavinon]

Thanks! Been talking to George offline though, I may be grabbing his whole assembly.

Isn't that kind of extreme to grab his whole assembly just to get his dreadnought? :D

[nspindel]

Lol :)

[KABII]

Greetings,

I made a request to DarqueKnight for his assistance in building the dreadnaught or building one for me. He recommended that I contact ben62670, and George Daniels.

I tried contacting Ben, however, he cannot receive anymore private emails. I have a pair of Polk SDA 2.3s and presently drive them with a Pioneer Amp. However, I have a HT rig with a Cinenova Grande 5 for an AMP. I want to drive my 2.3s using the Cinenova but have no A-1 transformer. Hence I need a Dreadnaught to resolve my problem.

Ben and/or George, please contact me at kabrown2@cox.net to discuss a build. Thanks for your time and consideration.

V/R

Ken Brown II
kabrown2@cox.net