1000 VA Dreadnought

crcolby · June 2020

Having finished all the internal mods for my SDA 1C pair, now I want to build a Dreadnought. I read DarqueKnight's excellent posts about the 800VA then the 1000VA transformers he used. The second of those was possible only because the manufacturer, Avel Lindberg, had specially manufactured a transformer for audio use. But A-L now routinely makes 1000VA transformers and has promised to send me specs soon which I can compare with Matthew Polk's recommendations for DC resistance, current saturation and such.

Actually, A-L makes a number of 1000VA transformers. All have the same toroid diameter, weight, height and regulation. But then they arerated for volts in the secondary at 25+25 upwards through 115+115, with corresponding currents ranging downwards (!) from 20A to 4.35A. I have no idea what these voltage and current specs mean, and certainly no idea what they say for the suitability of the various 1000VA transformers for use in a Dreadnought. A-L understandably doesn't want to involve itself in audio design. DarqueKnight's 800VA toroid carries the 115+115 rating. Is that the correct one to use? The only one?

DarqueKnight · June 2020

Avel-Lindberg recommended two 800VA transformers based on the specs provided by Matthew Polk. I chose the larger and higher current capacity Y236906 model. My AI-1 upgrade project was done 12 years ago in 2008. Avel-Lindberg, or another vendor, may offer a higher performance alternative.

The 1000VA transformer we use is the AV-047528, however, it is a special order item with a minimum order quantity. I would ask Avel-Lindberg which of their current 1000VA toroidal transformers comes closest to the AV-047528 in current capacity and especially in low noise performance.

audioluvr · June 2020

Their 800 VA transformer is a stock item. I built one of these and was really happy with the results. Some here have far superior systems than mine and preferred the 1000 VA tranny but I A/B'd them and on my system at least there was virtually no difference.

crcolby · June 2020

Thanks, folks. I had a thought about the mysterious 115+115 specification: this is A-L's way of saying the primary-secondary winding ratio is 1-1. A-L specifies that all its primaries are 115+115, which I take to mean they are assuming ordinary household AC voltage. Secondary would have the same voltage only when the winding was 1-1. The plus sign must indicate some kind of parallel/series choice. Anyway, I'll put DarqueKnight's question to A-L.

F1nut · June 2020

Get the Y236906 model, it's proven. You will be happy.

pitdogg2 · June 2020

Kind of interested in a response from
Avel-Lindberg for kicks.
Who knows we may need bigger, better, faster, leaps buildings in single sine wave sort of thing

Schurkey · June 2020

crcolby wrote: »

Thanks, folks. I had a thought about the mysterious 115+115 specification: this is A-L's way of saying the primary-secondary winding ratio is 1-1. A-L specifies that all its primaries are 115+115, which I take to mean they are assuming ordinary household AC voltage. Secondary would have the same voltage only when the winding was 1-1. The plus sign must indicate some kind of parallel/series choice. Anyway, I'll put DarqueKnight's question to A-L.

Well...close to 1:1, anyway.

crcolby · July 2020

I got this answer back from Avel Lindberg (more promptly than I have moved to post it here):
Hi Craig:

Based on current manufacturing, engineering offers as follows:

Total DC resistance of primary and secondary under 0.8 ohms and preferably under 0.5 ohms.

Please see the table below.

Inductance of primary and secondary should be at least 10mH and ideally around 14mH.

We don’t measure inductance on transformers and therefore values are unavailable, however, if the customer is after no load inductance on each primary and secondary values will be higher than 10mH.

Current capacity to saturation a minimum of 5 amps.

I am unsure about this request, usually the saturation current is applicable for inductors and not for transformers.

Turns ration of 1:1.

Please see the values below.

P/N DC resistance (Ohm) Turns ratio
Pri and Sec each at 115V
Y236906 TA800/115/AI Pri 0.55 Sec 0.75 Pri:1 Sec: 1.05
Y236956 TA1000/115/AI Pri 0.38 Sec 0.53 Pri:1 Sec: 1.038

audioluvr · July 2020

Order the Y236906

VSAT88 · July 2020

Yep that is what I was told ^ just three posts down. I sent an e mail off to them so we will see.

xschop · January 26

Is the Y236906 model still the go-to for the 800VA Dreadnaught build?

audioluvr · January 26

Yup

GlennDog · January 26

xschop wrote: »

Is the Y236906 model still the go-to for the 800VA Dreadnaught build?

one should opt for the 1KVA instead

Toolfan66 · January 27

GlennDog wrote: »

xschop wrote: »

Is the Y236906 model still the go-to for the 800VA Dreadnaught build?

one should opt for the 1KVA instead

If one can find one, the 800 is a fine piece to use, better than anything else, and has been proven, unless someone whats to try a group buy for the 1000, but I honestly don't think the demand is there anymore to make it worth while.

Maybe I'm wrong..

xschop · January 27

From what Ive found the 1000VA wont fit my enclosure. A description of the 800VA states it was 6.3"" OD. Has it changed?

Toolfan66 · January 27

I owned the 800 at first, sold it after the 1000 group buy, I don’t think the 800 was that much smaller than the 1000 if at all from what I remember.

Ray might have that info, or even a post about the two..

DarqueKnight · January 27

800VA Y236906 dimensions: 6.3" D, 2.2" H, 13.2 lbs.
1000VA AV-047548 dimensions: 7.28" D, 3.3" H, 22 lbs.

1000VA on left, 800VA on right.

Spec sheets for both transformers are attached.

honestaquarian · January 27

I smell another possible group buy

Toolfan66 · January 27

Okay, I do remember that now. Thanks Ray..

F1nut · January 27

IME, one could easily live with the 800 VA version.

Toolfan66 · January 27

F1nut wrote: »

IME, one could easily live with the 800 VA version.

100% Agree!!

DarqueKnight · January 27

Toolfan66 wrote: »

Okay, I do remember that now. Thanks Ray..

Toolfan66 wrote: »

F1nut wrote: »

IME, one could easily live with the 800 VA version.

100% Agree!!

You know you want a new 1000VA Dreadnought to go with your new 2.3TLs.

Toolfan66 · January 27

DarqueKnight wrote: »

Toolfan66 wrote: »

Okay, I do remember that now. Thanks Ray..

Toolfan66 wrote: »

F1nut wrote: »

IME, one could easily live with the 800 VA version.

100% Agree!!

You know you want a new 1000VA Dreadnought to go with your new 2.3TLs.

I have two of them, and I down modded my 1.2TL’s, and said goodbye to them about an hour ago. I made a straight cable for them, he will have to make his own dreadnought if he wants one, I told him if he wants help doing so I would help him put it together when he’s ready..

I kept my tweeter face plates, the crossovers I had built for them with the red face plates, the aluminum top and bottom plates, and the outside rings. Oh I did swap the passives out, I wanted to keep the one with Matt Polk’s signature.. 😎. So glad I had a spare set..

I’m looking forward to the 2.3tl project, I am keeping these some what simple, but will look very nice when done..

Sitka · January 27

I too am in the midst of building a Dreadnought (the 800VA version), and am curious if members here used the included steel bolt and hold down plate for mounting in an aluminum enclosure. I'm just wary of having all that steel next to the torroid. Also curious if we are still wrapping the coil in Dynamat.

Toolfan66 · January 27

Sitka wrote: »

I too am in the midst of building a Dreadnought (the 800VA version), and am curious if members here used the included steel bolt and hold down plate for mounting in an aluminum enclosure. I'm just wary of having all that steel next to the torroid. Also curious if we are still wrapping the coil in Dynamat.

Use an aluminum or stainless bolt if you can, I used aluminum..

F1nut · January 27

Also curious if we are still wrapping the coil in Dynamat.

I was not aware of someone doing that. It is the enclosure that is lined with Dynamat Xtreme.

Toolfan66 · January 27

F1nut wrote: »

Also curious if we are still wrapping the coil in Dynamat.

I was not aware of someone doing that. It is the enclosure that is lined with Dynamat Xtreme.

I think there was someone that did do that, don’t remember who though.

Yes just the enclosure..

GlennDog · January 27

I did it . . . no discernible difference

xschop · January 27

I thought someone wrapped their enclosure in copper tape.

pitdogg2 · January 27

xschop wrote: »

I thought someone wrapped their enclosure in copper tape.

I remember that

VR3 · January 28

I lined ptroopers enclosure in copper foil as per his request

1000 VA Dreadnought

Comments