The AI-1 Dreadnought Project Pt.1

headrott

drumminman wrote: »

What about switching the IC wires at the AI-1 binding posts - does the sound stage reverse or stay in the same place? Or does that make sense?

Are you talking about the leads from the transformer connected to the binding posts? Basically flip-flop them?

Greg

drumminman

headrott wrote: »

Are you talking about the leads from the transformer connected to the binding posts? Basically flip-flop them?

Greg

I was thinking about flip-flopping the IC cable at the binding posts - easier and would have the same effect. If the windings are unequal electrically (instead of 1:1, 1:1.04 or whatever), and this is the cause of the imaging problem, then it should follow whichever speaker is connected to that winding.

You'd know if the transformer was causing the imaging issue or if it was inherent in the speakers or recording.

headrott

drumminman wrote: »

I was thinking about flip-flopping the IC cable at the binding posts - easier and would have the same effect. If the windings are unequal electrically (instead of 1:1, 1:1.04 or whatever), and this is the cause of the imaging problem, then it should follow whichever speaker is connected to that winding.

You'd know if the transformer was causing the imaging issue or if it was inherent in the speakers or recording.

Ah gotcha. For me (right now) that's not an option because I am still using the blade portion for one of the cable ends. The pin wire is connected to a binding post though. When I make the other AI-1 using Larry's case I will probably add another binding post for the blade wire however. I then will be able to do what you're saying easily. Otherwise, I will have to swap the leads on the transformer which is a PITA to do.

While on this subject, how are you going to wire your AI-1 up to the 2.3TL's?

Greg

Edit: I don't know what my brain was thinking. You are talking about swapping them at the AI-1 binding posts themselves. I could do that. I will maybe be able to give that a try today. We'll see.....

Toolfan66

Greg,

The blade connects to the negative binding post so all you have to do is connect a wire of your choice from the AI-1 to one of the negative binding post...

Toolfan66

Lasareath wrote: »

I'd rather install a 6th binding post.

It would get him by Sal and not hurt anything as there is no mod to be done..

drumminman

Lasareath wrote: »

I'd rather install a 6th binding post.

On my 2.3TL's the blade is connected (on the interior side of the Xover) to the negative BP for the MW's. I suspect your 1.2TL's are wired the same and, if so, you could save yourself some touble and the cost of 1 pair of BP's.

headrott

Toolfan66 wrote: »

Greg,

The blade connects to the negative binding post so all you have to do is connect a wire of your choice from the AI-1 to one of the negative binding post...

It's been too long since I've seen the binding post cup(s) wiring so I don't remember for sure. So the blade connects to both the upper and lower negative binding posts? My pin now connects to the 5th binding post I connected. I obviously left the blade connected as it was. I was planning on installing a 6th binding post for the blade connection. If you and drumminman say I don't need to that's even better! So I can connect the blade output from the AI-1 binding posts to the either of the negative binding posts on the 2.3TL's? I ask because I am using banannas on the MIT shotgun S3's from the Aragon 8008bb to the 2.3TL's and was planning on using my Goertz python speaker cables with bananas for the AI-1 to the pin binding post and then go from the blade to the (as you suggest is possible) upper negative binding and connect my Shotgun's to the lower binding posts for the amp signal?

Greg

Toolfan66

Correct!!!

drumminman

headrott wrote: »

It's been too long since I've seen the binding post cup(s) wiring so I don't remember for sure. So the blade connects to both the upper and lower negative binding posts? My pin now connects to the 5th binding post I connected. I obviously left the blade connected as it was. I was planning on installing a 6th binding post for the blade connection. If you and drumminman say I don't need to that's even better! So I can connect the blade output from the AI-1 binding posts to the either of the negative binding posts on the 2.3TL's? I ask because I am using banannas on the MIT shotgun S3's from the Aragon 8008bb to the 2.3TL's and was planning on using my Goertz python speaker cables with bananas for the AI-1 to the pin binding post and then go from the blade to the (as you suggest is possible) upper negative binding and connect my Shotgun's to the lower binding posts for the amp signal?

Greg

If I understand correctly, you're not bi wiring, so you must be using jumpers between the upper (tweeter) and lower (MW) BP's. In that case you can use either negative BP.

But if you don't have the BPs jumpered you need to use the lower negative BP as the SDA signal only goes through the MW's

headrott

Lasareath wrote: »

Greg,

I think I figured out what was going on. Just recently within the past 14 days I switched from a standard Pin/Blade cable to the Ai-1 cable because I went to a dual Mono amp. I think this is when my placement of the center image has moved slightly to the left. The problem now is that I don't have any non-mono amps to test out the straight wire anymore.

So after switching back and forth between the original Ai-1 & the Dreadnought I realized that the placement of the center image is the same but with the Dreadnought the detail is better.

Sal

Thanks Sal for your findings. Yeah, the center image should sound the same with either AI-1 (Polk or Dreadnought). The difference I hear is in the SDA signal only. The center image is exactly in the center in my setup. The SDA signal seems slightly shifted to the left though. That is, the SDA signal seems to go further outside the speaker width on the left side than the right. Not sure if it's the mixing, my room, some other reason or due to the AI-1 though. I still haven't switched the speaker cable hookups on the AI-1 to see if that makes a difference though. After I do this I will post here though.

Greg

headrott

Toolfan66 wrote: »

Correct!!!

Cool Larry. Thanks for the info.

Greg

headrott

drumminman wrote: »

If I understand correctly, you're not bi wiring, so you must be using jumpers between the upper (tweeter) and lower (MW) BP's. In that case you can use either negative BP.

But if you don't have the BPs jumpered you need to use the lower negative BP as the SDA signal only goes through the MW's

Correct, not bi-wired. I have some home made jumpers installed.

Greg

Toolfan66

drumminman wrote: »

But if you don't have the BPs jumpered you need to use the lower negative BP as the SDA signal only goes through the MW's

I don't think so!!


Pull the binding post cup and on the back side you will see a jumper that ties the top and bottom negative binding posts, usually a little white wire with eyelets..

You can use the top post as well as the bottom..



So when one bi-amps they pull both jumpers on the outside but behind the binding post cup there is a jumper that keeps the negative binding post's tied together, so in reality one only needs to pull the positive jumper to bi-amp?? Just something to think about but it's true..

Toolfan66

Lasareath wrote: »

No Mod?, you're changing 4 Stock binding posts and adding a 5th?, Isn't that a mod?, While you have everything taken apart you might as well add a 6th binding post.

His have already been modded with a 5th binding post no reason to add a 6th unless he really wants to take them back apart and throw money at it thats not going to do anything..

Toolfan66

Toolfan66 wrote: »

I don't think so!!


Pull the binding post cup and on the back side you will see a jumper that ties the top and bottom negative binding posts, usually a little white wire with eyelets..

You can use the top post as well as the bottom..



So when one bi-amps they pull both jumpers on the outside but behind the binding post cup there is a jumper that keeps the negative binding post's tied together, so in reality one only needs to pull the positive jumper to bi-amp?? Just something to think about but it's true..

I should state that my 1.2's were like that and I can't speak for all the SDA's I am going to double check my tl's in the morning..

After thinking about it one should check theirs before doing so...

headrott

Toolfan66 wrote: »

I should state that my 1.2's were like that and I can't speak for all the SDA's I am going to double check my tl's in the morning..

After thinking about it one should check theirs before doing so...

That's good advice Larry. It is definately recommended to check before doing anything to make sure. I don't remember on any of my TL's as it's been too long since I've pulled the binding post cup. I am soon to install the "rings" for the binding posts though. I'll check mine.

Greg

headrott

huy wrote: »

Thank you Greg for all your valuable information. I will ask them.

huy, have you heard from TCM yet about the transformer winding inductance? I would like to order this one, but wouldlike to hear if they tested yours and the results they found. Thanks again huy.

Greg

headrott

Ray, do you think it may be worth the $11.00 more for the 1,000 VA transformer from TCM? Or, would it be unnecessary? The part number is :798.1202 and the link to the specs is here: http://www.toroid.com/standard_transformers/isolation_transformers/DataSheets/798.1202.pdf

Thank you Ray for the help.

Greg

DarqueKnight

headrott wrote: »

...do you think it may be worth the $11.00 more for the 1,000 VA transformer from TCM?

I can't say. Only TCM can address this within the context of an audio signal application. There is a point at which the increased amount of wire in larger transformers begins to have detrimental effects on audio signals.

headrott

DarqueKnight wrote: »

I can't say. Only TCM can address this within the context of an audio signal application. There is a point at which the increased amount of wire in larger transformers begins to have detrimental effects on audio signals.

Ok Ray. Thanks for the response. I will contact Ming again at TCM and see what he says.

Greg

RickTfromAZ

Having just built an AI-1 using the A-L transformer, I have a question. Does this transformer have a frequency range? In other words, could it be acting as both a high and low pass filter and rolling off useable frequencies?

RickTfromAZ

Also, for you guys kicking around the 1000VA transformer idea, here is a transformer that Avel-Lindberg offered to me when I placed an inquiry. It is not listed on their website. It is a "made special for audio, type AV-047548, which has an external shield to reduce magnetic interference".
Here are the limited specs that I have:
- 1000VA
- "Silent Technology Design"
- "integral peripheral magnetic screen"
- Resin filled center with an M8 central mounting hole
- 115V dual primary and secondary design
- 1:1
- Diameter-7.3"
- Height-3.4"
- Weight-22 lbs.
- Price-$155.00

No copper and iron losses were given by Avel-Lindberg.

DarqueKnight

RickTfromAZ wrote: »

Having just built an AI-1 using the A-L transformer, I have a question. Does this transformer have a frequency range? In other words, could it be acting as both a high and low pass filter and rolling off useable frequencies?

I don't see any evidence of LF or HF roll off in my room response measurements. I expect that Polk would have warned of such a possibility when they recommended the use of toroidal transformers for a custom AI-1 implementation.

RickTfromAZ

DarqueKnight wrote: »

I don't see any evidence of LF or HF roll off in my room response measurements. I expect that Polk would have warned of such a possibility when they recommended the use of toroidal transformers for a custom AI-1 implementation.

My reason for posing the question was because of two items that I came across on the A-L website. Granted, they apply to AC power, but it made me go....hmmm.

The first item relates to specifying the lowest operating frequency of the transformer. Read the last sentence of the technical notes on operating frequency.
http://www.avellindberg.com/transformers/tech_notes/tech_notes6.htm

Also, A-L lists the frequency range of their D4000 transformers as having a frequency range 47-400Hz.
http://www.avellindberg.com/transformers/d4000_range.htm

Again, this relates to AC power, but it really got me wondering.

DarqueKnight

RickTfromAZ wrote: »

My reason for posing the question was because of two items that I came across on the A-L website. Granted, they apply to AC power, but it made me go....hmmm.

If AC power is being stepped up or down by differences in coil sizes between the primary and secondary, then frequency is a concern.

An isolation transformer with a 1:1 turns ratio electrically "acts" like a straight piece of wire (rather than an inductor) with a gap cut into the midpoint. There is no physical connection between what is on the primary side and what is on the secondary side, but energy (the signal) is still transferred through inductive coupling.

RickTfromAZ

DarqueKnight wrote: »

If AC power is being stepped up or down by differences in coil sizes between the primary and secondary, then frequency is a concern.

An isolation transformer with a 1:1 turns ratio electrically "acts" like a straight piece of wire (rather than an inductor) with a gap cut into the midpoint. There is no physical connection between what is on the primary side and what is on the secondary side, but energy (the signal) is still transferred through inductive coupling.

Makes sense. Thank you for taking the time to answer.

nspindel

Did up my Dreadnaught today, works like a charm. I'm one of those crazy peeps using one with a common ground amp. I've been using a run of Signal Ultra speaker cable for quite some time as my SDA interconnect. I'm going to send that back to Frank and have him split it in half for me to use with the Dreadnaught, in the meanwhile I'm using some spare speaker cable that I think is quite inferior to the Signal. Even so, I'm definitely noticing a major improvement in bass, that's the first thing I've noted. Haven't done a whole lot of listening, but initial impressions are very good. I can't say that I'm blown away by the difference, because it's not like I used to use a stock AI-1, I don't really need to do this. But with all the talk that it may improve performance even with a common ground amp, I had to give it a shot.

Larry, thanks again for the case. You are an artist.

Pics to follow....

nspindel

Just checked - my first post in this thread was almost 3 years ago. About time I got this project done!

Toolfan66

Congrats!! And enjoy!!

thsmith

Is there any reason not to build a case from wood ?

Did Huy decide to buy a transformer from TCoM?