Dreadnaught build question

audioluvr

So after reading like a bazillion posts I've decided to go ahead and get one. Since they don't sell these on eBay and I hate waiting... I'm considering building one myself but I have a few questions:

1. Is the 1000VA one by AL available anywhere?
2. Does it matter if one IC cable is longer than the other ( I'm assuming, like speaker wire, they need to be the same but...)
3. What's the copper looking stuff lining the inside and what is it's function?

Thanks!

agfrost

1) No. You could call them and ask, but they're batch-built only by request. They should have the 800VA transformer on the shelf and that will get you nearly 100% of the way to the 1000VA's performance.

2) Not sure here. Symmetry appeals to my brain (and mine are same-length), but I wouldn't be surprised if it weren't critical. I've heard some say that equal-length speaker cable is not critical, but most go for symmetry.

3) Some put down copper sheeting, as extra (RFI?) insulation. If you put yours in a metal box, I'm fairly certain that the copper is unnecessary. Pretty bling, though!

pitdogg2

Others used Dynamat extreme instead of copper even in a metal enclosure.
I believe you must minimum order 25 to get the 1000va

audioluvr

Figures... I can't find reference to the Y236906 on their website any more though they have several 800 VA models. Looks like the Y236905 may be the closest currently available. Thoughts??

MrBuhl

Y236906 is your huckleberry! Last one on table below.

MrBuhl

Viking64

MrBuhl wrote: »

your huckleberry!

Just......no.

MrBuhl

^^ oh yea ^^ SCORE!

txcoastal1

http://forum.polkaudio.com/search?Search=Y236906

gimpod

audioluvr wrote: »

Figures... I can't find reference to the Y236906 on their website any more though they have several 800 VA models. Looks like the Y236905 may be the closest currently available. Thoughts??

That wont work, The primary and secondary winding's need to be the same voltages, a 1:1 isolation transformer.

The Y23 236906 transformer is still listed on there site You may have to buy direct.

He's right no one is carrying the Avel Lindberg Y236906 isolation transformer, Parts Express use to but not anymore unless you call and maybe special order it.

heiney9

I don't think you could ever get the Y236906 anywhere but direct. I know back when I was looking no vendor carried it. It had to be bought from AL.

OP, just call AL direct for the Y236906.

MrBuhl

^^ that's exactly how I got mine as well ^^ Direct from A/L

audioluvr

Oh. Some how my eyes wandered right past it. Thanks!

audioluvr

Does this thing get very hot during operation?

MrBuhl

Not at all.

westmassguy

audioluvr wrote: »

So after reading like a bazillion posts I've decided to go ahead and get one. Since they don't sell these on eBay and I hate waiting... I'm considering building one myself but I have a few questions:

1. Is the 1000VA one by AL available anywhere?
2. Does it matter if one IC cable is longer than the other ( I'm assuming, like speaker wire, they need to be the same but...)
3. What's the copper looking stuff lining the inside and what is it's function?

Thanks!

1. No, Special order only.
2. Possibly, but most likely no as long as you're using quality wire.
3. The case I use, which you probably saw in one of the threads, is Cast Aluminum. Aluminum is great for RF shielding. The Copper adds EMI shielding, which is different. The Copper Foil MUST be separated from the Aluminum by etching primer and several top coats of Enamel. Galvanic corrosion will result if you don't.

delkal

audioluvr wrote: »

2. Does it matter if one IC cable is longer than the other ( I'm assuming, like speaker wire, they need to be the same but...)

A electric signal propagates thru a wire at speeds close to the speed of light. You won't hear a delay in the sound if one cable was miles longer. Increased resistance / capacitance might begin to play a role but in a typical home setup I don't believe it.

But, there is a lot of voodoo when it comes to people hearing things with different cables. But I don't see how anyone can really hear a difference if one cable was a little longer than the other.

audioluvr

westmassguy wrote: »

audioluvr wrote: »

What's the copper looking stuff lining the inside and what is it's function?

The case I use, which you probably saw in one of the threads, is Cast Aluminum. Aluminum is great for RF shielding. The Copper adds EMI shielding, which is different. The Copper Foil MUST be separated from the Aluminum by etching primer and several top coats of Enamel. Galvanic corrosion will result if you don't.

Thanks Dave!

I WAS going to have you build this for me but budget being tight this time of year, i opted to do the build myself and use the savings for better options when I have you rebuild my crossovers.

audioluvr

One last question (ok, maybe not...) Does the box need to be grounded? I'm assuming yes but thought I'd check anyways

gimpod

audioluvr wrote: »

One last question (ok, maybe not...) Does the box need to be grounded? I'm assuming yes but thought I'd check anyways

No.

Schurkey

The transformer winding is asymmetrical. It's not a 1:1 ratio, and even the wire gauge is different primary-to-secondary.

Having the cables on the outside of the box a few feet different in length will make zero difference in the real world.

delkal

Schurkey wrote: »

The transformer winding is asymmetrical. It's not a 1:1 ratio, and even the wire gauge is different primary-to-secondary.

If the winding is asymmetrical it will change the voltage of the signal. Which side gets the higher voltage?

Does that change the sound?

audioluvr

Got it! $132 delivered to my door in 2 days! Now just need to build a box and wire it up! I'll post pics when I get going on it.

F1nut

Schurkey wrote: »

The transformer winding is asymmetrical. It's not a 1:1 ratio, and even the wire gauge is different primary-to-secondary.

Having the cables on the outside of the box a few feet different in length will make zero difference in the real world.

It's 115V - 115V.

Viking64

Does anyone have an opinion as to whether it makes a difference which wires go to which speaker? Blue/gray/violet/brown on one side and black/red/orange/yellow on the other.

Toolfan66

Viking64 wrote: »

Does anyone have an opinion as to whether it makes a difference which wires go to which speaker? Blue/gray/violet/brown on one side and black/red/orange/yellow on the other.

It does not make a difference..

Viking64

Toolfan66 wrote: »

It does not make a difference..

Thank you, Larry.

gimpod

Schurkey wrote: »

The transformer winding is asymmetrical. It's not a 1:1 ratio, and even the wire gauge is different primary-to-secondary.

Having the cables on the outside of the box a few feet different in length will make zero difference in the real world.

All Avel Lindberg Y23 Standard Range Toroidal Transformers have 115 + 115 V primaries and the secondary of the Y236906 are 115 + 115 V, That would make it 1:1 would it not.

From DK's The AI-1 Dreadnought Project Pt.1 Even though the pics are gone (Thanks EVIL Photobucket) it is still an informative read.

A couple of years ago, Matthew Polk provided the following specifications for a toroidal transformer based AI-1:

"1. DC Resistance of primary and secondary should be less than 0.8 ohms and preferably less than 0.5 ohms. The lower the better.

2. Inductance of both primary and secondary should be at least 10mH. Ideal is around 14mH.

3. Current capacity to saturation should be 5 Amps minimum.

4. Of course the turns ratio is 1:1."

Viking64 wrote: »

Does anyone have an opinion as to whether it makes a difference which wires go to which speaker? Blue/gray/violet/brown on one side and black/red/orange/yellow on the other.

@DarqueKnight wired his Y239609 as follows:

The dual primary and secondary winding's were wired in parallel as follows:

Right Pin = Red/Yellow

Right Blade (Negative Speaker Terminal) = Black/Orange

Left Pin = Grey/Brown

Left Blade (Negative Speaker Terminal) = Blue/Violet

Toolfan66

gimpod wrote: »

Schurkey wrote: »

The transformer winding is asymmetrical. It's not a 1:1 ratio, and even the wire gauge is different primary-to-secondary.

Having the cables on the outside of the box a few feet different in length will make zero difference in the real world.

All Avel Lindberg Y23 Standard Range Toroidal Transformers have 115 + 115 V primaries and the secondary of the Y236906 are 115 + 115 V, That would make it 1:1 would it not.

From DK's The AI-1 Dreadnought Project Pt.1 Even though the pics are gone (Thanks EVIL Photobucket) it is still an informative read.

A couple of years ago, Matthew Polk provided the following specifications for a toroidal transformer based AI-1:

"1. DC Resistance of primary and secondary should be less than 0.8 ohms and preferably less than 0.5 ohms. The lower the better.

2. Inductance of both primary and secondary should be at least 10mH. Ideal is around 14mH.

3. Current capacity to saturation should be 5 Amps minimum.

4. Of course the turns ratio is 1:1."

Viking64 wrote: »

Does anyone have an opinion as to whether it makes a difference which wires go to which speaker? Blue/gray/violet/brown on one side and black/red/orange/yellow on the other.

@DarqueKnight wired his Y239609 as follows:

The dual primary and secondary winding's were wired in parallel as follows:

Right Pin = Red/Yellow

Right Blade (Negative Speaker Terminal) = Black/Orange

Left Pin = Grey/Brown

Left Blade (Negative Speaker Terminal) = Blue/Violet

I took his question as wondering which way the dreadnought went when connecting it to the speakers (do these wires go to the left or right speaker) but yes the construction goes as you posted..

Basically once the dreadnought is complete there is no left or right side..

Viking64

Toolfan66 wrote: »

I took his question as wondering which way the dreadnought went when connecting it to the speakers (do these wires go to the left or right speaker) but yes the construction goes as you posted..

Basically once the dreadnought is complete there is no left or right side..

You are correct. That is what I meant. But actually it was that table that Gimpod posted from DarqueKnight's thread that made me question if there was a difference in the first place. I didn't want my new crossovers and dreadnought being part of a New Years Eve smoke show.

Schurkey

F1nut wrote: »

Schurkey wrote: »

The transformer winding is asymmetrical. It's not a 1:1 ratio, and even the wire gauge is different primary-to-secondary.

Having the cables on the outside of the box a few feet different in length will make zero difference in the real world.

It's 115V - 115V.

gimpod wrote: »

All Avel Lindberg Y23 Standard Range Toroidal Transformers have 115 + 115 V primaries and the secondary of the Y236906 are 115 + 115 V, That would make it 1:1 would it not.

Nope, in fact it confirms that it's NOT a 1:1 ratio.

Look at the intended purpose. The transformer was built to input 115 volts through the primary, and get 115 volts out the secondary.

That means the Copper and Iron Losses (transformer inefficiency) have to be "recovered" by adding extra length to the secondary windings (more windings) to bring the voltage on the secondary high enough so that you still have 115V after subtracting the losses.

The transformer was never designed to accept voltage on the secondaries, and then pull current from the primary. We do this, but it's not something the transformer was intended to do. WE use it as a symmetrical device, but that wasn't what it was intended for.

So, yeah, the SDA signal should be louder one direction than the other. DK says it doesn't matter in real life. I say it would be better if it was a true symmetrical transformer.

I looked around on the A-L web site, and did not confirm that the secondary windings are a different gauge wire from the primary...but I'm sure that's true, too.

audioluvr wrote: »

2. Does it matter if one IC cable is longer than the other ( I'm assuming, like speaker wire, they need to be the same but...)

My point in all this is to say that given the non-symmetrical nature of the transformer, and nobody seems to be able to hear a flaw or defect in the SDA volume, having a few feet more speaker cable attached to one side compared to the other will be of no importance at all.