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Review and Measurements of Dynaco ST 70

rebbiputzmaker

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That's not what I was asking. A rectifier rectifies. What property of a rectifier with the name "Mullard" stamped on it makes it superior to one with a different name stamped on it? How is that determined?

BTW, I looked up that amplifier. Oh my. The rectifier is the least of your worries there, the performance is somewhat lower than dreadful.
The GZ34 were all basically made by mullard, no matter what the marking. If there is seam on the top of the glass it was made in Japan not by mullard, the Mullards are better. The later Russian subs are not that good. The GZ34 had slow start and low voltage drop, a good tube. SS in an existing amp without slow start and padding the higher voltage is not the best idea. Pretty sure you know all of this already. :)

Also, SETs can be built that measure better, but they will never measure good. But, people do not buy or build them for measurements.
 

anmpr1

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Also, SETs can be built that measure better, but they will never measure good. But, people do not buy or build them for measurements.

Why would someone pay 7 large for an amplifier that measures like a '70s cassette deck? Why pay seven thousand dollars for a distortion circuit? If it's glowing you want, there are a lot of cheaper, better all around tube options. Holy cow, look at Bob Carver's beautiful 275 series tube amps, and compare the fit and finish with what Wavelength is selling for twice the price.

From their site it appears that Wavelength's main market consists of rock and roll guitar amplification. I don't want to characterize, but if ones idea of good sound is listening to a Les Paul through a distortion pedal driven into a Marshall stack with volume and gain turned up to 11, then it could be understandable.

One thing I don't understand, though, is Stereophile measuring the SET at 4 ohms. I'm guessing that the SET crowd is more into high sensitivity speakers. No one expects the designs to work well into lower impedance speakers. But with high efficiency speakers I'd wonder about noise.
 

sergeauckland

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Why would someone pay 7 large for an amplifier that measures like a '70s cassette deck? Why pay seven thousand dollars for a distortion circuit? If it's glowing you want, there are a lot of cheaper, better all around tube options. Holy cow, look at Bob Carver's beautiful 275 series tube amps, and compare the fit and finish with what Wavelength is selling for twice the price.

From their site it appears that Wavelength's main market consists of rock and roll guitar amplification. I don't want to characterize, but if ones idea of good sound is listening to a Les Paul through a distortion pedal driven into a Marshall stack with volume and gain turned up to 11, then it could be understandable.

One thing I don't understand, though, is Stereophile measuring the SET at 4 ohms. I'm guessing that the SET crowd is more into high sensitivity speakers. No one expects the designs to work well into lower impedance speakers. But with high efficiency speakers I'd wonder about noise.
Firstly, why do people choose SETs, it's because they're a distortion circuit. They have a characteristic sound, different from low distortion circuits, whether SS or tube. Why I don't understand is why anyone would buy a low distortion tube amplifier, given that then it would sound like a SS amp, but at 10x the cost. HiFi for some has nothing to do with High Fidelity, it's High Pleasure, and if they like the sound of distortion, so be it, their money, their (daft) choice.

As to 4 ohms or any other impedance, with tube circuits is doesn't matter, as the output transformer is tapped for 4, 8 or even sometime 16 ohms. SS amps will drive more power into 4 ohms than 8 ohms, (theoretically twice the power) but tube amplifiers will have the same power into 4 or 8 ohms provided of course that the correct tap is used....if it isn't the amp will distort even more.

Why would anyone buy a Rolex watch when a Casio keeps better time....clearly, a Rolex isn't bought for its timekeeping qualities any more than a SET amplifier is bought for its fidelity.

S.
 

anmpr1

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Firstly, why do people choose SETs, it's because they're a distortion circuit. They have a characteristic sound, different from low distortion circuits, whether SS or tube. Why I don't understand is why anyone would buy a low distortion tube amplifier, given that then it would sound like a SS amp, but at 10x the cost. HiFi for some has nothing to do with High Fidelity, it's High Pleasure, and if they like the sound of distortion, so be it, their money, their (daft) choice.

As to 4 ohms or any other impedance, with tube circuits is doesn't matter, as the output transformer is tapped for 4, 8 or even sometime 16 ohms. SS amps will drive more power into 4 ohms than 8 ohms, (theoretically twice the power) but tube amplifiers will have the same power into 4 or 8 ohms provided of course that the correct tap is used....if it isn't the amp will distort even more.

Why would anyone buy a Rolex watch when a Casio keeps better time....clearly, a Rolex isn't bought for its timekeeping qualities any more than a SET amplifier is bought for its fidelity.

S.
Yeah...I get all that. To each his own. But I don't get your analogy. Here's the thing. When you buy a Rolex (or Breitling or Patek) you get exquisite Swiss workmanship, along with pretty good time keeping. Not the best, but pretty good. When you buy this Wavelength thing, you get fair workmanship (compared to, say, Bob Carver's half the price product) and less than fair electrical performance. In fact, you get shoddy electrical performance. But, in the language of the 'high end' SET crowd, I guess you get good rhythm, pace, and timing. So it's like a Rolex for that. Just don't take it underwater. Lastly, when you die your son will be proud to own your Rolex. Not sure the same can be said about the Wavelength amp.

PS: As to the amp's 4 ohm taps--while it's true that most tube amps have them, the idea that you can run an SET using an inefficient 4 ohm speaker, using the appropriate taps, and get the same electrical response as something like an Avantgarde or Paul Klipsch horn loaded speaker, is not really correct.
 
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sergeauckland

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PS: As to the amp's 4 ohm taps--while it's true that most tube amps have them, the idea that you can run an SET using an inefficient 4 ohm speaker, using the appropriate taps, and get the same electrical response as something like an Avantgarde or Paul Klipsch horn loaded speaker, is not really correct.

If a SET amplifier has a 4 ohm tap, the loudspeaker's efficiency affects output level needed to achieve a certain sound pressure. If the loudspeaker's efficient, it will require fewer volts, and so the SET amplifier will be more linear than when driving more volts. A SET amplifier will also have a higher output impedance, stupidly high if the SET is one of those 'no feedback' amps, so the frequency response will depend on the loudspeaker's impedance characteristic. Horns are more sensitive than direct drivers, but if the user wants to use less efficient 'speakers, they will just need a more powerful SET. The electrical response of a SET/loudspeaker combination is easily understood from the amplifier's output impedance and loudspeaker's impedance characteristics.

S.
 

DKT88

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Firstly, why do people choose SETs, it's because they're a distortion circuit. They have a characteristic sound, different from low distortion circuits, whether SS or tube. Why I don't understand is why anyone would buy a low distortion tube amplifier, given that then it would sound like a SS amp, but at 10x the cost. HiFi for some has nothing to do with High Fidelity, it's High Pleasure, and if they like the sound of distortion, so be it, their money, their (daft) choice.

As to 4 ohms or any other impedance, with tube circuits is doesn't matter, as the output transformer is tapped for 4, 8 or even sometime 16 ohms. SS amps will drive more power into 4 ohms than 8 ohms, (theoretically twice the power) but tube amplifiers will have the same power into 4 or 8 ohms provided of course that the correct tap is used....if it isn't the amp will distort even more.

Why would anyone buy a Rolex watch when a Casio keeps better time....clearly, a Rolex isn't bought for its timekeeping qualities any more than a SET amplifier is bought for its fidelity.

S.
I have a pair of tube amps that are very low distortion, relatively high power (100W each), modest negative feedback, wide bandwidth, highly regulated power supplies. I put them together at a cost of $2.5K in 1998. I enjoy listening to them. I have a Hypex 500 WPC amp too. There's something emotional, not logical, about the tube amps and that's part of listening to music.
 
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rebbiputzmaker

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Why would someone pay 7 large for an amplifier that measures like a '70s cassette deck? Why pay seven thousand dollars for a distortion circuit? If it's glowing you want, there are a lot of cheaper, better all around tube options. Holy cow, look at Bob Carver's beautiful 275 series tube amps, and compare the fit and finish with what Wavelength is selling for twice the price.

From their site it appears that Wavelength's main market consists of rock and roll guitar amplification. I don't want to characterize, but if ones idea of good sound is listening to a Les Paul through a distortion pedal driven into a Marshall stack with volume and gain turned up to 11, then it could be understandable.

One thing I don't understand, though, is Stereophile measuring the SET at 4 ohms. I'm guessing that the SET crowd is more into high sensitivity speakers. No one expects the designs to work well into lower impedance speakers. But with high efficiency speakers I'd wonder about noise.
I would not personally spend that much either on an amplifier. I have built several SETs And in the proper setting they do sound very nice. Also they can be relatively low in distortion. Again not like a SS amp, or some higher-end push pull circuits but very listenable, with a natural to the ear harmonic envelope which is what the SET does. Many older speakers are higher impedance, so I also do not really get using a four ohm load. If you look at the original western electric 300B curves you’ll see the quality of the tube. Wavelength does make very attractive, more than I would spend by far, stuff. His main business is home audio not the guitar amps, but the guitar amps are very beautiful with good parts and good sound also.
 

Labjr

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I've owned the Wavelength amps for over 25 years. Well before the reviews were out and prices started to rise. Even though Stereophile editor mentioned that they weren't for everyone, they were given a Class A rating. And rightly so. Gordon Rankin is an incredibly talented designer with a good ear who spares no expense in providing some of the very best sounding equipment you can buy. He's a great guy to deal with. And he still emails me with suggestions for improving my listening experience, and sent different tubes for me to try. Not sure about the numbers to date but at the time, he personally hand-wired hundreds of pairs which were sold.

Everyone I've ever demoed the amps for has been blown away by what they hear. Including a local high end dealer. My dad had a Dynaco ST70 that didn't sound nothing like my SET amps.

If you haven't listened to good SET amps, you shouldn't be making ridiculous generalizations about them.


P.S: I believe it was Gordon Rankin who started the USB DAC craze when he came up with idea to code asynchronous USB data for audio use which made it possible to reduce jitter to sub-audible levels. Thus making hi-fi quality audio possible over USB.
 

anmpr1

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Gordon Rankin is an incredibly talented designer with a good ear who spares no expense...

OK. I'll give the designer the benefit of the doubt. But about sparing no expense? More expense was required in order to make the thing work. At least according to the linked review. See last paragraph, below.

But first, let's break this $7000.00 film down. Stereophile claims the designer wants to save the rainforest, so he's donating one of the price of the amp's Clevelands to some rainforest fund. That knocks it down down to 6 large. The amp uses something called Siltech cable. I never heard of it, but the company has a sales sheet, and I picked one of their items out at random--the Crown Princess Royal Signature Series pure silver anti-Vampire cable (I made up the vampire thing, but the rest of the name is legit). Let's say Wavelength gets it at half price, $2000.00. This brings the amp's parts cost to 4 thousand. The amp uses a Golden Dragon 300 B tube. I couldn't find a current price for those, but 300Bs run about 150-200 dollars. Then you've got a recitifier and driver tube. So let's up it to 3 C-notes. $3700.00. Then you've got some transformers. Who knows what they cost? Custom made? We'll set aside a thousand dollars, but my guess is that is way over whatever he's paying for them. $2700.00. Then he's got to put the thing together inside his bespoke rain forest box. Let's say that's another thousand dollars, along with his time. $1700.00. OK. I guess that's a 'reasonable' profit on a seven thousand dollar amp. Especially if it can save some rain forest. But is it really a 'spare no expense' design? Let's ask the reviewer--the sort of guy who might actually be in the market for this kind of machine.

The reviewer said that out of the box it wasn't quite there, yet. It sounded 'gritty and congealed'. At first I was wondering whether he was talking about his porridge, but it was the amp he was describing, all right. Since the reviwer is a knowledgable single-ended audiophile kind of guy, he knows what to do about gritty sound. He suspended the chasis on some Shun Mook Super Diamond Resonators, used a set of Michael Green Cable mounts, and topped it off with some imported Italian tube dampers. Finally, Shakti Stones on the transformers. Then it happened. Not at first, but after a while, "the heavy gauge Siltech hookup wire inside the amp settled in and loosened up (hope that didn't create any electric shorts)." Leading both the reviewer and his wife, Kathleen, to 8 watt sonic nirvana.

Not sure anything more needs to be said. What more can be said?
 

anmpr1

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Maybe you need a hobby, :)
Maybe I do need a new hobby. After building two tube amps and two tube preamps, I'm ready to take up something a bit more interesting. Like base jumping in a wingsuit. LOL

Actually, I use a tube amp in my main system now. I have nothing against tube amps. But this super expensive SET thing has reached levels of ridiculous that is hard to comprehend. And I realize that it's just money, and I understand about a fool and his money. And I understand too about how a Rolex and a Timex both measure the same thing. But if it's my dad, and when it's time for the old man to beam up, I want his Rolex, and not his Wavelength SET. ;)
 

invaderzim

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.... But is it really a 'spare no expense' design? ....

It could be a 'spare no expense' at using expensive components design rather than a spare no expense at making it sound great design. A bit like the $5,000 hamburgers that some places like to sell with weird and expensive things on them.

... And I realize that it's just money, and I understand about a fool and his money. ....

And for some people that money is really nothing. I was watching a show the other day on the people that process animals through Heathrow airport. A family had the choice to either put their dog in quarantine for a few weeks in England or send it back to Germany (where they apparently have a home too). They opted to send it back to Germany... on a private jet for what the show said cost around $30,000. They didn't even travel with it, the jet was just for the dog.
 

SIY

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It could be a 'spare no expense' at using expensive components design rather than a spare no expense at making it sound great design.

That's exactly it. Money for the sake of money spent on things that have no effect on the sound while not engineering the things that do.

Re: the price, for most technical gear I've been involved with, retail has to be 4-5x cost of BOM, so considering the latter, the former is not unreasonable. Of course, considering that this is a unit with roller coaster frequency response and horrific distortion and efficiency, the BOM cost is ridiculous when looked at logically. But it's not sold as an amp (a device to make a small signal larger), it's intended more as a fetish-object, and for that purpose, it's clearly suitable.
 

sergeauckland

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That's exactly it. Money for the sake of money spent on things that have no effect on the sound while not engineering the things that do.

Re: the price, for most technical gear I've been involved with, retail has to be 4-5x cost of BOM, so considering the latter, the former is not unreasonable. Of course, considering that this is a unit with roller coaster frequency response and horrific distortion and efficiency, the BOM cost is ridiculous when looked at logically. But it's not sold as an amp (a device to make a small signal larger), it's intended more as a fetish-object, and for that purpose, it's clearly suitable.
Exactly this. No tube amplifier since 1970 has any engineering justification, it's all been about 'the sound', the looks and peer group approbation. The 2N2955 PNP complement to the 2N3055 sealed the fate of tube amplifiers as being obsolete. As to SETs, they were obsolete by the 1920s when Push-Pull configurations were developed as a way of avoiding the horrendous distortion caused by single-ended DC through the output transformer. PP balanced the magnetic field and allowed ungapped output transformers, with their much greater efficiency and lower losses.

It's almost as if somebody rediscovered the Stanley Steamer as a better alternative car.

https://en.wikipedia.org/wiki/Stanley_Motor_Carriage_Company

S
 

SIY

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Exactly this. No tube amplifier since 1970 has any engineering justification, it's all been about 'the sound', the looks and peer group approbation.

Well, there's also a weird geek enjoyment to extracting high performance out of an obsolete technology (which is one major reason I design and build tube equipment).
 
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