Powerful Tube Amp for SF Strads?

I know were are talking about absolute "reference" level speakers and components here, but I'm surprised that with this many suggestions and responses so far, no one has recommended simply trying Paul Speltz Zero Autoformers to increase the impedance seen by Llyod's amplifiers.

They can be used to double, or even quadruple, the load seen by the amplifiers. As a result, amps that "run out of steam" may often handle previously impossible speakers without breaking a sweat. In many, many, systems, insertion of the Zeros not only remove the impedance issue, they are undetectable from a sonic standpoint. Give the FAQ a read.

Not saying they are guaranteed to work in every situation, or even this particular one, but for $450 in the naked version and $950 in the boxed, it is a far cheaper, and easier, experiment than all the fantastic amps being suggested. And even high-powered tube or solid state amps can still benefit from seeing a higher impedance.

I know this sounds like an ad, but I haze no connection to the company, professional, financial, or otherwise. Just passing on a little suggestion from the world of high-efficiency speakers/low-power SET amps and OTL amps.

Hi Lloyd,

Zero's are nothing more than impedance matching transformers(actually autoformers - just a primary instead of the primary & secondary in transformers). They serve exactly the same function as output transformers in tube power amplifiers, which are used to match the impedance of the output stage to the speakers.

Paul Speltz seems like a great guy from his postings and is extremely proud and confidant of his product. It probably wouldn't be difficult to get a trial out of him. He also can wind custom Zeros for specific situations,if I remember correctly. Although, yours is a fairly basic one.

Of course, excess power and headroom are always a good thing with all speakers, especially medium to low efficiency ones. So, in the end, you may need 100-300+ watts to fully realize the potential of your Strads on dynamic passages. Even then, though, the Zeros would help.

personally i see no reason to go OTL first and put in Speltz Autoformers later because of bad speaker impedance. why not choose 'good' speakers first?

Agreed, but sometimes a person is already heavily invested in their speakers(emotionally or financially) and the Zeros are a low cost(& effort) way to seem if a particular amp will work to their satisfaction.

In Lloyd's case, his system wasn't designed around removing output transformers(OTL), so the philosophical transgression of adding an autoformer isn't as big a factor.

That's awesome, Lloyd. I bet those Strads really shine with the extra reserve power on tap.

Better tell your neighbor to get used to it, because from here out "The House's gonna be rockin"