The AI-1 Dreadnought Project Pt.2 - Upgrade to 1000VA Transformer

[DarqueKnight]

The wires on the AV-047528 use the same color scheme and parallel connections as the Y236906:

To parallel, put 0 to 0V (blue & violet) and 115 to 115V ( grey & brown) on the primary side and 0 to 0V (orange & black) and 115 to 115 (yellow & red) on the secondary side.

[Toolfan66]

Thanks Ray!!

I figured as much just looking at the pictures but thought I would ask..


How come every time you start a new thread I seem to be spending money?

[drumminman]

No kidding! I'm still burning in my Avel 800 KVA AI-1. Trying to resist the urge to even follow this thread, but. . .

[Toolfan66]

Cool!! I received all my goodies today, I will finish this tonight...

Ray you are right that transformer is almost to big for this case and at what 82lbs? It is heavy!!!

[DarqueKnight]

If your transformer weighs 82 lbs, they sent you the wrong one. The spec weight is 22 lbs.

[Toolfan66]

I was exaggerating..

[Toolfan66]

I was exaggerating..

82lbs would be one big ass transformer..

All I have left to do is solder and Dynamat the cover..

[Toolfan66]

Ok!!!

First and foremost thanks Ray for doing what you do. Again another great upgrade by the master of SDA's..

Now I have this put together and listening to Tool's Undertow album, I was listening to this as I was putting together the new Dreadnought so I had something familiar running in my head.. Oh and fantastic album by the way..

The first thing that hit me was the bass, much more depth and more pronounced, second was the way the music enveloped me, I also feel the vocals are more forward and more natural in position to the drums.

I will leave it at that for now and get a few hours in listening to more familiar music..

Very happy with what I'm hearing so far...

[DarqueKnight]

It's all in your mind...placebo effect.

[DarqueKnight]

Did you ever pursue the Jantzen inductors for the HF crossover section?

I did.

Parts Express provided the following price information:

Jantzen 0.4 mH 22 AWG, Jantzen part number 1489, $2.86 each.
Jantzen 0.65 mH 26 AWG, Jantzen part number 1772, $2.33 each.

These are special order items and would take 8-12 weeks to receive.

I placed an order for the Jantzen perfect lay inductors today. I also ordered Jantzen 0.4 mH 22 AWG, 1.25 mH 20 AWG ( part #1137, $5.63 each) and 2.50 mH AWG inductors (part #1695, $6.61) for my three pairs of CRS+'s. Solen does not offer a perfect lay 0.4 mH, 1.25 mH or 2.50 mH perfect lay inductor.

Bev Ruggiero at Parts Express said my parts should arrive sooner than 8 weeks because they are preparing a large order from Jantzen and will tack my order on to theirs.

[agfrost]

It's all in your mind...placebo effect.

[Toolfan66]

It's all in your mind...placebo effect.

So you get commission off all this crap you sell us?




Your the only one that knows its truth though...

[DarqueKnight]

So you get commission off all this crap you sell us?

Of course. That's one of the ways I finance my nice audio toys and other bad habits.

[Toolfan66]

Of course. That's one of the ways I finance my nice audio toys and other bad habits.

I had a feeling that's what was happening.


I can honestly say what I like best about this transformer is the bass at lower volumes, very nice indeed..

[drumminman]

I had a feeling that's what was happening.


I can honestly say what I like best about this transformer is the bass at lower volumes, very nice indeed..

G-r-o-o-a-a-n-n-n-n-n-n-n

It's probably good (for my wallet) that Avel has no more of the 1000 KVA's

[Toolfan66]

I placed an order for the Jantzen perfect lay inductors today. I also ordered Jantzen 0.4 mH 22 AWG, 1.25 mH 20 AWG ( part #1137, $5.63 each) and 2.50 mH AWG inductors (part #1695, $6.61) for my three pairs of CRS+'s. Solen does not offer a perfect lay 0.4 mH, 1.25 mH or 2.50 mH perfect lay inductor.

Bev Ruggiero at Parts Express said my parts should arrive sooner than 8 weeks because they are preparing a large order from Jantzen and will tack my order on to theirs.

Did you talk to him on the phone or email??

[thsmith]

Ray, if order the Plitron would you be willing to evaluate it ?

[RickTfromAZ]

I placed an order for the Jantzen perfect lay inductors today. I also ordered Jantzen 0.4 mH 22 AWG, 1.25 mH 20 AWG ( part #1137, $5.63 each) and 2.50 mH AWG inductors (part #1695, $6.61) for my three pairs of CRS+'s. Solen does not offer a perfect lay 0.4 mH, 1.25 mH or 2.50 mH perfect lay inductor.

Bev Ruggiero at Parts Express said my parts should arrive sooner than 8 weeks because they are preparing a large order from Jantzen and will tack my order on to theirs.

Good for you. I can hardly wait for the results.

[Toolfan66]

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

Am I missing something? If the above statement is true why don't these numbers match? It seems the 800VA had numbers closer then the 1000VA.

[FTGV]

Out of curiosity and correct me if I'm wrong but the inductance of the transformer winding is connected in parallel with the 16mh coil is it not?If that being the case and with the transformer windings wired in parallel equaling roughly 3-4 mh (depending upon pri. or sec. winding) would result in roughly 2-3 mh across that circuit branch instead of 16 mh.One would expect such a change to alter considerably the bandwidth covered by the dimensional drivers.Connecting the windings of the transformer in series would of course have less dramatic a shift in total inductance being roughly 5-6 mh.Either way there would also be a desirable decrease in DC resistance across that leg which should net improvements in the bass department.

[headrott]

Ray, if order the Plitron would you be willing to evaluate it ?

I am also interested in ordering the Plitron 1KVA transformer. I would be intereted in the results of the transformer if you buy one and Ray does an evaluattion.

Greg

[DarqueKnight]

Did you talk to him on the phone or email??

I sent the initial inquiry by email, them placed the order by phone. Bev (Beverly) is a unisex name, but this Bev is a woman.

Ray, if order the Plitron would you be willing to evaluate it ?

Sure.

[DarqueKnight]

I recently asked Ken Swauger if he had the original AI-1 specs. He did not. He referred my inquiry to Stu Lumsden (Polk's engineering VP) and Matthew Polk. Here is Matthew Polk's response:

"The original isolation transformer was successful at eliminating the issues of SDA with non-common ground amps but at the cost of a significant compromise of the SDA sound stage. We later figured out how to do this right with the transformer incorporated into the SRT controller.

The transformer is a 1:1 ratio and allows the L-R and R-L SDA signals to be derived while isolating the grounds of the two amp channels. The inverted portions of the SDA signals only need a bandwidth from a little below 100Hz to 1.6kHz. It's helpful if the transformer has more bandwidth on the top end since the high-end cutoff is controlled by a low-pass in the cross-over. At the low end, however, it's best if the transformer windings have a very high inductance as measured with the secondary open, around 14mh, and a very low DCR.

In the mid-range where SDA operates, the SDA drivers on one side operate in series with the SDA drivers on the other side with the signals passing through one set of SDA drivers then through the transformer and then through the set of SDA drivers on the other side. However, at low frequencies the positive part of the signal passes through the SDA drivers and is shunted directly to ground by an inductor in parallel with the transformer. The result is that the SDA drivers operate in parallel with the stereo drivers at low frequencies but operate in series with the other side to produce the SDA difference signal in the mid-range. If the DCR is too high, as it was in the original isolation transformer, it will reduce the level of the SDA signal and alter the bandwidth. If the inductance isn't high enough, also the case in the original, it will raise the low-end cutoff of the SDA signal further reducing the SDA soundstage and allow the SDA drivers to produce too much upper bass thereby muddying the sound.

The transformer in the SRT controller had a DCR around .3 ohms and an inductance around 14mh as best I recall. Current carrying capability before saturation is also an issue and was not adequate with the original. I think it was only about 3 amps which would be about 60 watts to the SDA drivers and not enough. I don't recall exactly what it was in the SRT but seem to recall something like 10 amps which would deliver about 600 watts to the SDA drivers.

As a practical matter we found the only way to get a low enough DCR was with a 1:1 toroidal transformer. These are available off the shelf but expensive. Because of the efficiency of the toroid the cores must be much larger to avoid saturation.

Hope that helps.

-msp

Figure 1. SDA SRS 1.2TL SDA crossover circuit schematic.

I measured the DCR and winding inductance of my original AI-1. Inductance was measured at 100 Hz with the other side shorted and again with the other side open. Measurements were taken inside the AI-1's case at the transformer terminals.

Original AI-1 Isolation Transformer Primary:
DCR: 0.22 ohm
Inductance (measured at 100 Hz): 13.88 mH (secondary shorted), 125.88 mH (secondary open)

Original AI-1 Isolation Transformer Secondary:
DCR: 0.25 ohm
Inductance (measured at 100 Hz): 14.25 mH (primary shorted), 125.95 mH (primary open)

================================================== =====

Avel Lindberg Y236906 Isolation Transformer Primary (Dual Windings
Parallel Connected):
DCR: 0.28 ohm
Inductance (measured at 100 Hz): 6.01 mH (secondary shorted), 197.59 mH (secondary open)

Avel Lindberg Y236906 Isolation Transformer Secondary (Dual Windings Parallel Connected):
DCR: 0.38 ohm
Inductance (measured at 100 Hz): 6.55 mH (primary shorted), 215.44 mH (primary open)

================================================== =====
Avel Lindberg Y236906 Manufacturer Supplied Specs:

Avel Lindberg Y236906 Isolation Transformer Primary (Dual Windings Parallel Connected):
DCR: 0.275 ohm
Inductance: 153.3 mH

Avel Lindberg Y236906 Isolation Transformer Secondary (Dual Windings Parallel Connected):
DCR: 0.360 ohm
Inductance:168.8 mH

================================================== ====

Avel Lindberg AV-047548 Isolation Transformer #2 Primary (Dual Windings Parallel Connected):
DCR: 0.24 ohm
Inductance (measured at 100 Hz): 3.75 mH (secondary shorted), 262.55 mH (secondary open)

Avel Lindberg AV-047548 Isolation Transformer #2 Secondary (Dual Windings Parallel Connected):
DCR: 0.29 ohm
Inductance (measured at 100 Hz): 4.10 mH (primary shorted), 286.8 mH (primary open)

================================================== ====

In the case of the original AI-1 and A-L Y236906, there were some differences between the manufacturer's specifications and my transformer inductance measurements. Inductance varies with frequency, and I do not know the frequency at which the manufacturer's inductance measurements were taken. MY MCP BR2822 LCR meter generates test frequencies at 100 Hz, 120 Hz, 1,000 Hz and 10,000 Hz. I could not match the manufacturer's inductance specs at any of those frequencies.

My Y236906 DCR measurements agreed with Avel Lindberg's specs. My primary and secondary inductance measurements were approximately 45 mH higher. The ratio of primary to secondary inductance of my measurements was close to Avel Lindberg's"

My Y236906 open circuit inductance measurements: 197.59 mH (primary)/215.44 mH (secondary) = 0.9171

A-L's Y236906 open circuit inductance measurements: 153.30 mH (primary)/168.80 mH (secondary) = 0.9082

I wonder if there were different versions of the AI-1. Matthew Polk said the AI-1 had a very high transformer winding DCR, but I measured only 0.22 ohm and 0.25 ohm for the primary and secondary. I did measure close to the specified 14 mH primary and secondary inductance, but only with the other side shorted. In the open circuit case, the inductance of both sides was approximately 126 mH. If the open circuit inductance is the required parameter, then each of the A-L inductors

Original AI-1 primary and secondary open circuit inductance (at 100 Hz): 125.88 mH and 125.95 mH.

Avel Lindberg Y236906 primary and secondary open circuit inductance (at 100 Hz): 197.59 mH and 215.44 mH.

Avel Lindberg AV-047548 primary and secondary open circuit inductance (at 100 Hz): 262.55 mH and 286.8 mH.

[FTGV]

Original AI-1 primary and secondary open circuit inductance (at 100 Hz): 125.88 mH and 125.95 mH.

Avel Lindberg Y236906 primary and secondary open circuit inductance (at 100 Hz): 197.59 mH and 215.44 mH.

Avel Lindberg AV-047548 primary and secondary open circuit inductance (at 100 Hz): 262.55 mH and 286.8 mH.

Since it appears Matt Polk suggested measuring with open secondary these inductance numbers look more realistic and all will put you in the desirable 14-15 mh range when paralelled with the big 16 mh coil.

[headrott]

Ray, if order the Plitron would you be willing to evaluate it ?

Sure.

Is there any news about this evaluation of the Plitron 1KVA? Has it been oredered an sent to Ray to evaluate? I am wondering because I will wait until after the evaluation to order one if there is going to be an evaluation by Ray. Otherwise, I will simply order one if there is no evaluation planned as I believe there is no better alternative available. I guess that means I should order one regardless, huh? I am simply interested in the evaluation results if there is going to be one. Could you guys let (me) us know? Thanks very much.

Greg

[thsmith]

I am ordering one on Monday. Need to see if they will send it directly to Ray or to me then Ray.

Ray, sending you a PM.

[thsmith]

Order has been placed but will have to be shipped to me first then I will ship to Ray.

[headrott]

Order has been placed but will have to be shipped to me first then I will ship to Ray.

What was the total cost with shipping? Does it quote a time when you will recieve it? Thanks for doing this for us.

Greg

[thsmith]

$305, says 10 days but we will see.

Thank Ray for his testing. I hope it yields good results.

[thsmith]

Got this today from Plitron.

Your order with Plitron Manufacturing Inc. is scheduled to ship on 03/23/12.