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

headrott

fjross wrote: »

I will confirm with A-L that the specs for the minimum order run will be identical to the AV-047528 and not just a modified Y-236956 1000va. I was in touch last week and melonie said that she would check to see how there were coming along with the pricing and lead time. I will check on Monday again.

Excellent Dave! Thank you very much for the effort.

Also, thanks to Ray and thsmith for helping us find out what works best for the Dreadnought.

Greg

quadzilla

I'm in for the AV--047528 if this happens. I probably won't be checking this thread a lot, so please pm me if this actually goes through.

JayCee

FTGV wrote: »

I assume some of you gents are even using these trannies with common ground amps ?

michaeljhsda2 wrote: »

I am with very good results.

DK,

Will this project benefit all common ground amps?

Thanks,

John

FTGV

JayCee wrote: »

Will this project benefit all common ground amps?

Thanks,

John

For one I would expect the sub 100hz stereo signal bass produced by dimensional drivers to have greater output and better definition resulting from reduced series DCR.

DarqueKnight

JayCee wrote: »

Will this project benefit all common ground amps?

I don't know. The only common ground amp I own is the 16 year old Adcom GFA-555 Mk II used in my office system at work. The 1000VA A-L transformer increased sound stage width and depth and overall clarity and detail compared to the custom interconnect cable. The system components are:

Nakamichi CA-5AII Preamplifier (vintage 1990)
Yamaha TX-1000U Digital Tuner (vintage 1993)
Yamaha CDX-1110U CD Player (vintage 1988)
Adcom GFA-555 Mk II Power Amplifier (vintage 1995)
Polk Audio SDA CRS+ Speakers (extensively modified, vintage 1989)
Signal Cable Analog 2 Interconnects
Monster Cable Z2 Reference Speaker Cable
Signal Cable Power Cords (Pre and Power Amps)

JayCee

FTGV wrote: »

For one I would expect the sub 100hz stereo signal bass produced by dimensional drivers to have greater output and better definition resulting from reduced series DCR.

DarqueKnight wrote: »

I don't know. The only common ground amp I own is the 16 year old Adcom GFA-555 Mk II used in my office system at work. The 1000VA A-L transformer increased sound stage width and depth and overall clarity and detail compared to the custom interconnect cable.

I have a Sunfire 300/2 (1995-recently refreshed by Rita's) powering my 1.2TL's...XO's are fully modded to include tweets, Larry's rings and the Solen 10g 16mH inductors. I also have fully upgraded 1C's (minus the Solen inductor) powered by a Parasound 1500a. On both systems the sound stage width and depth is great, but I'd like to see a bit more from the mid range. I'm leaning towards going in on the transformer group buy and taking this project on. Bottom line, was the AI-1 a dramatic change to your systems or just an incremental move in a positive direction?

Toolfan66

It was a Night and Day change using the AI-1 Dreadnought..

JayCee

Toolfan66 wrote: »

It was a Night and Day change using the AI-1 Dreadnought..

Using a common ground amp?

drumminman

JayCee wrote: »

Using a common ground amp?

JayCee, when I built mine (the original AL 800VA transformer) I heard improvement with my common ground amp described here:

http://www.polkaudio.com/forums/showthread.php?129134-AI-1-Dreadnought-with-common-ground-amp

But that was without burn in, which definitely improves the sound. That initial review was also written using crappy Monster speaker cable to connect to the AI-1. When I upgraded to a litz DIY design the improvement was even greater. To sum up, bigger soundstage, more relaxed and realistic sounding instruments, cleaner/clearer vocals.

If the 1000VA sounds even better this one's a no brainer.

JayCee

drumminman wrote: »

If the 1000VA sounds even better this one's a no brainer.

Drumminman,

I was on vacation when your thread was created and missed it entirely. Definitely seems like a worthwhile pursuit with the possibility for appreciative gains...and will be fun to try.

I've decided to push ahead and I placed my name on the group buy list for 2. If it doesn't work out for either or both of my rigs, I'm sure I'd be able to offer them down the road to a CP member that did not have the opportunity to do this right now.

Thanks for the link and your impressions,

John

DarqueKnight

fjross,

I cannot reply to your PM because your in box is full..

dracoskeeper

I'm in if the AV-047528 order gets done!!!!

FTGV

JayCee wrote: »

.XO's are fully modded to include .... and the Solen 10g 16mH inductors.

In that case my previous statement would likely not apply since you have already significantly reduced series DCR with the inductor change.

fjross

DarqueKnight wrote: »

fjross,

I cannot reply to your PM because your in box is full..

Cleared.

JayCee

Toolfan66 wrote: »

It was a Night and Day change using the AI-1 Dreadnought..

JayCee wrote: »

.XO's are fully modded to include .... and the Solen 10g 16mH inductors.

FTGV wrote: »

In that case my previous statement would likely not apply since you have already significantly reduced series DCR with the inductor change.

Larry, I hope I've not missed something and this isn't a stupid question, but if IIRC your 1.2's have the Solen inductors installed. Since mine do, too, does your comment above apply to using the Dreadnought in conjunction w/the Solens?

Toolfan66

Yes!! And Yes!! Ray hit a home run with this last Avel transformer and I just got lucky they found the one I received, She originally told me there wasn't anymore to be had only to email me a couple days later that she found one and that it was the last one to be had..

Don't get me wrong the 800 works great (better then the original AI-1 and better then strapping the negs on the amp) the new AL 1000 takes it to a new level and my system sounds really sweet right now.

I haven't been upgrading anything for awhile now but my house has been my priority at the moment, new paint and gutters and having the roof looked at this week. So my between that and the Camaro my rig is taking a back seat for a few, but I'm very happy with it at the moment so no big deal..

JayCee

Toolfan66 wrote: »

Yes!! And Yes!!

Excellent, thanks for confirming this.

DarqueKnight

JayCee wrote: »

DK, Will this project benefit all common ground amps?

DarqueKnight wrote: »

I don't know. The only common ground amp I own is the 16 year old Adcom GFA-555 Mk II used in my office system at work. The 1000VA A-L transformer increased sound stage width and depth and overall clarity and detail compared to the custom interconnect cable. The system components are:

Nakamichi CA-5AII Preamplifier (vintage 1990)
Yamaha TX-1000U Digital Tuner (vintage 1993)
Yamaha CDX-1110U CD Player (vintage 1988)
Adcom GFA-555 Mk II Power Amplifier (vintage 1995)
Polk Audio SDA CRS+ Speakers (extensively modified, vintage 1989)
Signal Cable Analog 2 Interconnects
Monster Cable Z2 Reference Speaker Cable
Signal Cable Power Cords (Pre and Power Amps)

Figure 1. The CRS+'s are 5'-1-1/2" apart inside edge to inside edge. I sit 8' back. The room is 11" x 11".

With the custom heavy gauge (9 AWG) interconnect cable, the sound stage extended wall to wall, but height was limited to the top of the speakers and depth was limited to the space between the front plane of the speakers and the rear wall.

With the 800VA Dreadnought, the aerial shape of the sound stage changed from a shallow rectangle to a wide "m" shape. Expressed another way, the sound stage shape changed to a crescent moon with a bump in the middle. The crescent peaks and the middle bump extended 1 foot from the front speaker plane. Sound stage height increased to just above, or up to 6" above, the top edge of the speakers a depending on the music.

With the 1000VA Dreadnought, the aerial shape of the sound stage was a deeper "m" shape. The crescent peaks and the middle bump extended 2 feet from the front speaker plane. Sound stage height increased to just below the top of the bookcases depending on the music.

I was surprised at the degree of spatial spread. Sound images that were confined to the space between the speakers moved in front of the speakers with the 800VA Dreadnought. The same images were moved to the side walls with the 1000VA Dreadnought.


Figure 2. On either side, the sound stage curves along the side wall: 1 foot forward with the 800VA
Dreadnought and 2 feet forward with the 1000VA Dreadnought.


Figure 3. "The cockpit" with nice vintage audio components."


Figure 4. Top to bottom: Nakamichi CA-5AII Preamplifier (vintage 1990), Yamaha TX-1000U Digital Tuner
(vintage 1993), Yamaha CDX-1110U CD Player (vintage 1988).


Figure 5. Adcom GFA-555 Mk II Power Amplifier (common ground amplifier, vintage 1995).


Figure 6. Comparing 1000VA Dreadnought on left and 800VA Dreadnought on right. The 1000VA won.


Figure 7. I shouldn't have done this. I took the PS Audio Power Plant Premier (PPP) AC regenerator from my
master bedroom system to try it out in the office system. Now I want one for the office.

Since I usually have to listen at "background music" sound levels, I appreciated the greatly increased low level detail, particularly with regard to image weight and bass definition and articulation. I initially thought the 800VA Dreadnought would be overkill in this small space, but it brought Such Good Sound that I was tempted to try the 1000VA Dreadnought...and after that, the AC regenerator.

The AC regenerator brought further enhancements in clarity, detail and holography, plus a small enhancement of depth beyond the boundary of the rear wall. However, the overall improvement with the AC regenerator was much smaller in degree than the improvement of the 1000VA Dreadnought over the 800VA Dreadnought.

Conclusion

In a small space, with vintage components of moderate resolution, including a classic common ground power amplifier, both the 800VA and 1000VA Dreadnought brought substantial improvements in clarity, detail, image weight and spatiality compared to a heavy gauge (9 AWG) custom interconnect cable. In the future, when I am more dedicated to audio than I am now, I can envision getting a used PPP AC regenerator for the office system...but I am trying to talk myself out of it.

References

CRS+ 1989-Version-PCB-Xover-and-SDA-Inductor-Upgrade

Driver-and-Passive-Radiator-Rings-For-The-SDA-CRS+

Upgrade Jantzen Inductors for the CRS+ - Figures 11-13

---

You are trying to talk yourself out of buying new audio gear? I can't imagine that you are trying too hard.

Really, I am trying to talk myself out of getting a PPP...because I really want a P3 AC regenerator for the office system.

drselect

Nice office setup DK.
What type of wires did you use to connect the Dreadnought to the CRS?
And cmon you know what the results were going to be with the PPP . Especially with all of those lights, EEs, and electrons floating around your work.:cheesygrin:

PS If you don't mind me asking who did the art work?

Drenis

I'm a bit lost here.

Are you saying that all SDA models sound better?benefit with a custom external transformer over just a custom SDA cable even when using a common ground amp?

DarqueKnight

drselect wrote: »

What type of wires did you use to connect the Dreadnought to the CRS?

Sorry for neglecting to mention that. The Dreadnought cables are Monster Cable Z3 Reference speaker cable.

drselect wrote: »

And cmon you know what the results were going to be with the PPP . Especially with all of those lights, EEs, and electrons floating around your work.:cheesygrin:

Well, I try not to take things for granted...the PPP has not always resulted in a positive outcome, especially when it comes to running power amps.

drselect wrote: »

PS If you don't mind me asking who did the art work?

I did the artwork. The metal wall sculpture in my office is a copy of the acrylic "Music Signal" wall sculpture in my home theater room.

Drenis wrote: »

I'm a bit lost here.

Are you saying that all SDA models sound better? benefit with a custom external transformer over just a custom SDA cable even when using a common ground amp?

No, I am saying that with the common ground amplifier I use, two custom transformers sounded much better than a custom interconnect cable. Other forum members have tried the transformer interface with other common ground amps and liked the results.

As are all of my modification reports, this is just a discussion of results and a suggestion for the interested reader to consider.

drumminman

DarqueKnight wrote: »

Other forum members have tried the transformer interface with other common ground amps and liked the results.

As are all of my modification reports, this is just a discussion of results and a suggestion for the interested reader to consider.

I built the AI-1 interface using the the 800VA A-L transformer per DK's diy instructions, and it brought substantial improvement to my system with my common ground amp. IMHO and with my set up it's a no brainer - one of the better mods I've done, perhaps just a step below Xover upgrades.

I've ordered the 1000VA transformer in the group buy - totally stoked to get that in the system.

heiney9

Where did everyone purchase the 800VA Avel Lindberg Y236906? Looking to make one for future use. Googling gives me very little info. Just curious if they have to be bought direct from the factory or somewhere else.

H9

Drenis

I'm not sure I understand how this mod works exactly in conjunction with how it provides an improvement. I also fail to see what the transformer does when its just a single wire connecting each speaker.

I'm going to do some searching and reading on this today.

heiney9

It's not a single wire, there is a postive and a negative, this is one reason why only certain SDA's can use the AI-1. Other SDA's are wired differntly. I was unsure all these years that it would provide a benefit for common ground amps, but apparently it does. For non-common ground amps it isolates the grounds of the amplifier so as not to damage the amp and/or speakers. In essence when using a non-common ground amp you are shorting the signal path when the SDA interconnect is in place, the isolation transformer eliminates the short.

There has been a lot of discussion over the years, but the search function is difficult to use. Try searching using Google. I'm sure others will chime in to either correct me if I misstated something or expand on the subject.

H9

Drenis

Thanks for the info Brock.

I assumed the blade portion was strictly for support but I see it is also attached to the negative terminals and carries a signal for the use of isolation. That makes sense now as to how it isolates with the use of non-common ground amplifiers.

I need to learn how the transformer works WITH common-ground amps to understand how this works to improve things. This is quite fascinating. Christ I'm going to end up dropping more in mods then I paid for my speakers. :razz: But oh the end result...

heiney9

Drenis wrote: »

Christ I'm going to end up dropping more in mods then I paid for my speakers. :razz: But oh the end result...

Yeah, but you'll have ten times the speaker compared to what you can buy today for the total cost invested. And have something fairly unique. Friends still come over and are amazed at my 1C's.

H9

DarqueKnight

heiney9 wrote: »

Where did everyone purchase the 800VA Avel Lindberg Y236906? Looking to make one for future use. Googling gives me very little info. Just curious if they have to be bought direct from the factory or somewhere else.

The Y236906 can be special ordered from Parts Express or ordered directly from Avel Lindberg. You can only place an order with AL by telephone. The person who has taken my orders in named Melanie.

Drenis wrote: »

I assumed the blade portion was strictly for support but I see it is also attached to the negative terminals and carries a signal for the use of isolation. That makes sense now as to how it isolates with the use of non-common ground amplifiers.

The blade of a pin/blade cable is not attached to anything. Both wires are attached to the pin. The pin/blade connectors at the end of the AI-1 interface cables do have separate wires for the pin and the blade.

Drenis wrote: »

I need to learn how the transformer works WITH common-ground amps to understand how this works to improve things. This is quite fascinating.

For both common ground and non-common ground amplifiers, the heavy duty toroidal transformer provides a lower noise, lower impedance path for the dimensional signals. The dimensional signal is half the amplitude of the stereo signal and is more affected by the electrical noise generated by the opposite power amplifier channel and the opposite speaker's drivers. With the pin/blade cable, the return path for the dimensional signal is through the other speaker's dimensional circuit and the amplifier's ground (negative) circuit. For a common ground amplifier, this means that each speaker "hears" the electrical noise in both channel's ground circuit. Furthermore, due to both speaker's direct electrical connection through the pin/blade cable, each speaker "hears" the other speaker's electrical noise generated by the drivers and other circuit elements in the send path of the dimensional circuit.

With the AI-1, the dimensional signal has its own electrically isolated send and return paths. There is no direct electrical connection between the speakers and no way for noise generated in one speaker to be transferred to the other speaker. When the AI-I is used with a common ground amplifier, there is still a common ground path connection between amplifier channels. In the second circuit below, an amplifier common ground (negative) connection represents a "short" between one primary lead and one secondary lead of the transformer. However, since there is no positive connection associated with that short, it is essentially an infinite impedance (open circuit) path and the dimensional signals going through the transformer cheerfully ignore it.

Low frequency stereo and dimensional circuit for SDA SRS 1.2TL with interconnect and with AI-1.

Drenis wrote: »

Christ I'm going to end up dropping more in mods then I paid for my speakers. :razz:

Yes, that is a very real possibility. In my case(s):

SDA SRS 1.2TL cost: $2,550; mod cost to date: $4,328.
SDA SRS cost: $1,400; mod cost to date: $2,414.
SDA CRS+ Pair #1 cost: $426; mod cost to date: $1,490.
SDA CRS+ Pair #2 cost: $500; mod cost to date: $1,935.*
SDA CRS+ Pair #3 cost: $500; mod cost to date: $1,935.*

*The mod costs for the 2nd and 3rd pair of CRS+'s was substantially higher than the 1st pair due to cabinet re-veneering, higher cost SDA inductors and higher cost parts for the heavy duty AI-1 interface.

Drenis wrote: »

But oh the end result...

...was well worth it because it was much more economical than buying new high performance speakers.

Drenis

DarqueKnight wrote: »

The blade of a pin/blade cable is not attached to anything. Both wires are attached to the pin. The pin/blade connectors at the end of the AI-1 interface cables do have separate wires for the pin and the blade.

I had questioned this when I studied the inside of my terminal cups and saw the connection. I then began thinking WTF because I knew from reading that the SDA signal could travel on a single wire.

DarqueKnight wrote: »

For both common ground and non-common ground amplifiers, the heavy duty toroidal transformer provides a lower noise, lower impedance path for the dimensional signals. The dimensional signal is half the amplitude of the stereo signal and is more affected by the electrical noise generated by the opposite power amplifier channel and the opposite speaker's drivers. With the pin/blade cable, the return path for the dimensional signal is through the other speaker's dimensional circuit and the amplifier's ground (negative) circuit. For a common ground amplifier, this means that each speaker "hears" the electrical noise in both channel's ground circuit. Furthermore, due to both speaker's direct electrical connection through the pin/blade cable, each speaker "hears" the other speaker's electrical noise generated by the drivers and other circuit elements in the send path of the dimensional circuit.

With the AI-1, the dimensional signal has its own electrically isolated send and return paths. There is no direct electrical connection between the speakers and no way for noise generated in one speaker to be transferred to the other speaker. When the AI-I is used with a common ground amplifier, there is still a common ground path connection between amplifier channels. In the second circuit below, an amplifier common ground (negative) connection represents a "short" between one primary lead and one secondary lead of the transformer. However, since there is no positive connection associated with that short, it is essentially an infinite impedance (open circuit) path and the dimensional signals going through the transformer cheerfully ignore it.

I did some reading up on the A1-1 today. With that and your explanation, I now understand how this works. I was contemplating PMing you with questions but you laid it all out here. You are a wealth of knowledge.

DarqueKnight wrote: »

...was well worth it because it was much more economical than buying new high performance speakers.

I had been wanting to hear LSi/LSiM's now for some time now but decided to take a plunge into unknown territory and so far, I have no regrets or desires to pursue that any longer.

I'll probably have more direct questions for you as I progress with changes.

DarqueKnight

Drenis wrote: »

I had been wanting to hear LSi/LSiM's now for some time now but decided to take a plunge into unknown territory and so far, I have no regrets or desires to pursue that any longer.

If you have the opportunity to hear properly set up LSi's and LSiM's...and other high quality speakers, I would urge you to do so for educational and reference purposes.