ZERO, Autoformers, Impedance Multiplying, Transformer cables

[Guest " "]

http://www.tnt-audio.com/accessories/zero_autoformer_e.html

anyone ever use one or see any reviews?

[awsjr]

I have a set...homemade boxes and use them with my magnepaner smga (4ohm) and a Nakamichi SR-2A amp.....also rebuilt the xo's which was pretty simple (maybe dean remembers those big 50uF auricaps).....Paul is a good guy to talk about your set up....liberal return policy if I remember....settled on the 3x taps (12ohms).....email me if you want more info -Al

[Edgar]

I know Paul Speltz from my previous association with the Audio Society of Minnesota. While I have never heard his autotransformers in action, Paul knows his way around electronics pretty well, and is very active in the Atma-Sphere User's Group.

http://www.zeroimpedance.com/

Edgar

[Guest " "]

I was surprised to see a cable with a transformer in it. Cetainly surprised it never came up in all the cable snake oil discussions.

I read thru his site. He has a lot of technical info. The basis of the claims of his cable is consistent with the views of having autoformers in xovers, but he adds an intresting twist in that the tap settings change the load seen by the amp 4/8/6, etc.

There have been a lot of folks who report hot running amps due to having to drive a 4 ohm klipsch xover. Seems like this may be an option.

I may send off an e-mail to determine the watt rating of his DIY version.

Would also want to know if the amp load is isolated from the speaker's imediance or is it derived from it. In other words, with no speaker attached, what is the load on the amp?

Does anyone have any other questions that they would like included?

The price is fair for the DIY version.

[Edgar]

I believe that the main focus of the product is the transformer, not the cable. If I remember correctly, Paul originally sold just the transformer, then added cables to it in response to demand.

Being transformers, they do exactly what transformers do: transform the impedance. This is a particularly effective with OTL tube designs because they REALLY don't like low impedance speakers -- I believe that Paul's original motivation for designing the ZEROs was his love of Atma-Sphere OTLs.

The big difference between the ZERO transformers and standard output transformers on most tube amps is the impedance ratio. Most tube amps match a primary (source) of perhaps a couple of thousand Ohms down to a secondary (load) of 16 or 8 or 4 Ohms; the ZEROs maybe go from a primary of ~16 Ohms down to a secondary of 4 Ohms or even less. But the load seen by the amp at the primary is always directly proportional to the actual load connected to the secondary.

Edgar

[Guest " "]

I believe that the main focus of the product is the transformer, not the cable. If I remember correctly, Paul originally sold just the transformer, then added cables to it in response to demand.

Being transformers, they do exactly what transformers do: transform the impedance. This is a particularly effective with OTL tube designs because they REALLY don't like low impedance speakers -- I believe that Paul's original motivation for designing the ZEROs was his love of Atma-Sphere OTLs.

The big difference between the ZERO transformers and standard output transformers on most tube amps is the impedance ratio. Most tube amps match a primary (source) of perhaps a couple of thousand Ohms down to a secondary (load) of 16 or 8 or 4 Ohms; the ZEROs maybe go from a primary of ~16 Ohms down to a secondary of 4 Ohms or even less. But the load seen by the amp at the primary is always directly proportional to the actual load connected to the secondary.

Edgar

I sent off an email with some minor questions.

Also wondering if he has smaller versions for use in surround sound systems. Probally could get by with smaller ones for the surround channels. Imagine having 8 of the featured transformers behind your HT amp.

[Guest " "]

I have a set...homemade boxes and use them with my magnepaner smga (4ohm) and a Nakamichi SR-2A amp.....also rebuilt the xo's which was pretty simple (maybe dean remembers those big 50uF auricaps).....Paul is a good guy to talk about your set up....liberal return policy if I remember....settled on the 3x taps (12ohms).....email me if you want more info -Al

 

Looks like you also have them in the recomended spot.

[Al Klappenberger]

Guys,

These transformers are simply autotransformers just like the T2A in the Klipsch AA and the 3619 I use in my networks. The difference is that they are wound with more wire on a toroid form to allow them to go lower. All they do is make 4 Ohms into 8 Ohms or 8 ohms into 16 ohms, the inverse of that or any ratio like that. I really don't think it's too usefull unless your speaker impedance doesn't match what your amp likes to see. They should not change the sound at all otherwise.

Al K.

[Guest " "]

Guys,

These transformers are simply autotransformers just like the T2A in the Klipsch AA and the 3619 I use in my networks. The difference is that they are wound with more wire on a toroid form to allow them to go lower. All they do is make 4 Ohms into 8 Ohms or 8 ohms into 16 ohms, the inverse of that or any ratio like that. I really don't think it's too usefull unless your speaker impedance doesn't match what your amp likes to see. They should not change the sound at all otherwise.

Al K.

 

Al, your universal AA xover upgrade has always been one of my favorites. I often find myself recommending it to folks that are considering doing cap upgrades and other tweaks to their AA's.

Back to this device, I am wondering if it would or could be useful for folks who have reported that their amps are running frying pan hot after connecting two pairs of 4 ohm speakers. Assuming the new load is 2 ohms, then the device could doulbe it back to 4 ohms and help with this issue.

Not knowing the power handling ability of the main product offering, I am wondering if it may be over built for use in heritage line speakers. The things look like they can handle more than 500 watts. The cost for the DIY version is about 230 each, at least 2 would be needed.

Related question for anyone, Does anyone have specs for the t2a, the 3619, or Bob's version? I always wondered about the bandwidth, in particular on the lower end and any data to evaluate saturation power levels associated with lower end cutoff frequency decisions and any effect on upper frequencies. More and more folks are reporting better imagining and detail of middle and high frequencies by using higher frequencies cuttoff on the lower end of the autoformer.

[Guest " "]

Well it has been a few weeks since I posted this thread. Events since last post. I found 3 autoformer devices with similar ladder stepped windings and connections.

The first is the Zero device. A well made, wide bandwidth unit. Cost is 430 per pair, so we will put it aside for now.

The second is the atlas af140. This is a time tested autoformer that can be used to step up or step down the impedance an amp sees. Price is about 52 bucks.

The third is the emm330 by edcor. This unit is one of many in the edcor line. price is about 51 bucks.

So I ordered a set of AF140's to determine if there is anything to this notion that increasing the load an amp sees will provide some specific noticeable improvements.

i connected it up to my onkyo amp and 2004 lascalas. I connected using a 1.5X impedance multiplication factor. So it should take the 6 ohm average impedance of the AL-4's and let the amp see 9 ohms.

Results thus far. There is something here worth investigating further. I am going to listen to them for a few days. I'm going to put together a check list using all the claims out there for benefits of impedance multiplication and do a true or false assessment of the claim.

So far, I can't recall an item at any price that has had such a dramatic effect on the sound of my SS amp.

Before anyone runs out and buys an autoformer and attempts to use it in this manner on an SS amp, make sure you understand if your amp can drive an inductive load as well as ensuring your system is rigged to prevent DC signals from reaching your speakers (use of sub-sonic filters or use of sub-woofer cut off circuits). Older Capacitance coupled amps will not have a problem, but direct coupled amps that can not drive a 2 ohm load will have issues if you inadvertently send a DC (0hz) signal thru your amp.

[sunnysal]

I was under the impression that size mattered in the bandwidth area for these type of trannnies. the atlas is rated 30hz-15khz IIRC. I suspect the T2A is similar or less. I wonder what units can be bought standalone that cover 10-20? these guys are using toroid..I wonder what would on order from www.toroid.com that would do the job? tony

[Guest " "]

sunnysal

If you find one, let me know, I'll buy it for my test. I have been looking and could not find one. It would need to have 5 taps min, and be configured as a stepped ladder autoformer.

Toroid has a kit you can use to build one for about 100 bucks each. For 175 bucks they provide an engineering service to help you figure out the windings you would need. The checklist to request the service is not intuitive. You could not just say I want the windings requirement for an air core version of the AF140.

The zero is a good peice of work. The bandwidth of the zero is 2hz - 2mhz. It is rated at 124 watts at 2hz.

The t2a is reported to have a high ceiling, but due to it's size, it would saturate pretty quickly at the lower end of the audio spectrum.

The iron core autoformers I refered to are pretty large. the AF140 wieghts 3 lbs.

My assumptions and operating framework.

a.) The atlas AF140 covers 30hz - 15khz

b.) My LaScalas cover 53hz - 17khz

c.) My SS amp covers 10hz - 100khz

My purpose right now is to evaluate some of the perception claims of using imedance multiplication. It is too early to tell if any of those perceptions are derived from using an air core inductor vs an iron core one. Intial indications are that the reported claims are simply as a result of imedance multiplication, even if done with an iron core autoformer.

[Deang]

http://www.tnt-audio.com/accessories/zero_autoformer_e.html

"The most important thing to remember about the ZERO Autoformers is: if there is no significant impedance mismatch, then there will be no real benefit to using the ZEROs."

[Guest " "]

http://www.tnt-audio.com/accessories/zero_autoformer_e.html

"The most important thing to remember about the ZERO Autoformers is: if there is no significant impedance mismatch, then there will be no real benefit to using the ZEROs."

Thats true.

I have seen that link.

But I am thinking that "significant impedance mismatch " might be a judgment call. I wouldnt think that putting a pair of LaScala's (4 - 6 ohm speakers), on an amp that could drive 2, 4, 8, ohm loads is a significant impedance mismatch.

I certainly did not expect any significant differences in sound quality by increasing the impedance by a factor of 1.5 X. But the results were consistent with reports by others who have used these devices.

I also think there are some senerios in which folks want to run 2 sets of speakers on vintage 2 channel equipment or may want to add second woofers to existing xovers that may warrant some impedance multiplication work.

My interest here is to determine if the claims are based on using the impedance multiplication device, or the air core version of these devices.

So far, it turns out, if you understand how these autoformers work, it is pretty easy to duplicate the impedance multiplication functionality these devices have.

[Deang]

I've noticed the variety of recent network purchases you've made. With the ESN and Universal Type A -- you have no use for these devices between the amp and the speaker. They basically provide a function already build into these networks -- providing a constant and benign load to the amplifier.

[Guest " "]

I've noticed the variety of recent network purchases you've made. With the ESN and Universal Type A -- you have no use for these devices between the amp and the speaker. They basically provide a function already build into these networks -- providing a constant and benign load to the amplifier. 

Intially, the analysis of the functionality of these devices was not related to my personal use, but rather the investigation of performance claims associated with an unusal product type.

However, indications are that the constant load provided by the networks you refer to may not be enough, depending on the amp type in actual use.

[Erik Mandaville]

"Cetainly surprised it never came up in all the cable snake oil discussions."

These have been mentioned in the past several times, and I brought them up more recently in response to Bob's DIY battery charger -- 'always another project...' -- thread.

Erik

Some of the responses to Bob are here:

http://forums.klipsch.com/forums/1/751612/ShowThread.aspx#751612

[Erik Mandaville]

"I've noticed the variety of recent network purchases you've made. With the ESN and Universal Type A -- you have no use for these devices between the amp and the speaker. They basically provide a function already build into these networks -- providing a constant and benign load to the amplifier."

Respectfully, I guess I think that whether someone needs something (impedance multiplying devices or a slice of pizza) is probably best left up to the person in question. The 'ZEROs' weren't really designed to reflect a constant friendly load to an amplifier (though that certainly may be one added benefit) as much as they were to provide a higher, or in this case 'multiplied,' impedance. For example, some owner's of SET amps have found that using the 4 ohm secondary on the output transformer sounds better into an 8 ohm speaker load than the 8 0hm tap on the OPT. However, if an amplifier is factory-set for a 4 ohm output z, and does not provide a means to change that impedance at the user level, than the device mentioned above is one possible solution.

Another example: My Lowther drivers have an impedance of 15 ohms, and I had found I preferred the 8 ohm tap on my former 2A3 Moondogs than I did the 16 ohm.

The Moondog secondary impedance on the output transformer can be changed, but only by going into the amp and reconfiguring combinations of wires to achieve the desired tap. Unless someone is able to solder and/or knows what those combinations of wires are, they won't be able to make the change. While not cheap, the 'ZERO' is again one way of achieving the desired higher impedance, and evidently quite a few people prefer the higher impedance load -- regardless of the type of crossover they may be using, which in the case of the Lowthers is.......zero.

Erik

[Deang]

Uhg, I can't believe I just spent half a morning reading all the material on his site. O.K., I see what you guys are saying now. However, on his FAQ page he does say this:

"The ZEROs are the simplest type of transformer called an auto-transformer or autoformer. They are used to multiply the impedance of any speaker so that it "feels" like the optimum load for the amplifier being used. They are very helpful in matching speakers to amplifiers. By adjusting the speaker's impedance, both the damping factor and the maximum power transfer of the amp/speaker can be tailored for the best sound."

As far as impedance multiplicaition goes -- I can see maybe playing with a pair of these if you are using one of Al's designs, where you could actually double or quadruple impedance (Cornwall ALK) and get a straight 16 ohms, but I'm not sure it would be such a great idea with any of the earlier stock Klipsch designs, where impedance through the midrange is already pretty high from the amps perspective. This also leads to the issue of something like the ZERO exasperating issues in FR from peaks in impedance caused by the horn.

[Guest " "]

Erik Mandaville

I understand and agree with your comments.

You have certainly done your homework in this area and are obviously familuar with impedance multiplying devices such as the zero device.

Known, but by few, are the iron core autoformers with high power ratings with the needed stepped ladder tapped windings to accomplish the step-up or step-down cited in your examples.