AudioNervosa

Systemic Development => Amplification and Preamplification => Tubes => Topic started by: Brap on January 17, 2017, 09:45:33 AM

Title: VTA ST-70
Post by: Brap on January 17, 2017, 09:45:33 AM
Well, my best friend is FINALLY getting into 2 channel, specifically tube gear so, I'm building a Bob Latino ST-70 for him with all the fixins. Upgraded caps, matched quad and stepped attenuator. Haven't built anything in 2 years  and getting the itch.
Title: Re: VTA ST-70
Post by: sleepyguy24 on January 17, 2017, 12:40:47 PM
Have fun with the build. I saw in another forum people speak nicely of the Bob Latino kits.

http://emotivalounge.proboards.com/thread/47280/bob-latino-vta-120-tube

I saw this kit a couple of years ago and was drooling over it. I'm not much of a DIYer.

http://www.thetubestore.com/Parts-Accessories/Amps-and-Amp-Kits/Elekit-TU-8300R-Single-Ended-Tube-Amp-Kit
Title: Re: VTA ST-70
Post by: Brap on January 17, 2017, 12:53:36 PM
If you want to drool, check out Transcendent sound, their Son of Beast.  I built one and an OTL is really a sweet sound.
Title: Re: VTA ST-70
Post by: tmazz on January 17, 2017, 07:44:28 PM
I have not built any eletronics for at least 30 years now, but I have to say they were fun projects back when I had the time to do them.

Maybe now that retirement is just around the corner.........
Title: Re: VTA ST-70
Post by: richidoo on January 17, 2017, 08:58:00 PM
Looking forward to following your build and reading your opinion on the SQ of the ST-70, Brap. 
Title: Re: VTA ST-70
Post by: Brap on January 18, 2017, 06:50:23 AM
Well, I previously built one for myself but with some slight modifications to the one I will start tonight. Mine has Gelelex KT-66's and Mundorf SGO caps.  This one will be EL-34 and K42-Y PIO caps.  I compare now with my OTL and I really like the ST-70 amp but with my Zu Druids, I prefer the OTL and with my Paradigm's I prefer the ST-70! Maybe something to do with speaker crossovers or just the difference with SDFR speaker versus traditional 3 way. Would like to hear comments on this as to why.  I will compare my ST70 to the one I  build and will report!
Title: Re: VTA ST-70
Post by: richidoo on January 18, 2017, 03:29:33 PM
The output impedance of the two amps is different. OTL has a LOT of negative feedback which lowers the source impedance to like 0.1 ohms. That will really affect some speakers that are designed with solid state amp in mind, like Paradigm/Anthem.

Normal tube amps usually have less feedback, higher source impedance and weaker damping. Some people like this as warmer, softer sound. SDFR speakers sound better with less electrical damping. Nelson Pass wrote an article on First Watt website about this, talking about his current source amps, which have no electrical damping at all.
http://www.firstwatt.com/pdf/art_cs_amps.pdf
There may be other articles there, this is the first hit I  found on goog.

When I was building boxes for my featrex D5nf FR drivers I built a LM1875-based current source chip amp which made the SDFR sound very good. Stopped all the shouting they tend to do. But the 1.5ohm source impedance tube amp Manley Snappers were even better. But Cary SLI-80 was atrocious as were many normal voltage source solid state amps. It's a weird thing.
Title: Re: VTA ST-70
Post by: tmazz on January 19, 2017, 07:01:14 AM
I don't think it's weird at all. It is just more complicated that most people realize or at least are willing to admit.

Over my years in this hobby I have dealt with many measurement objectivists who would say that there was no difference between two components because the measured the same. And when a while bunch of us listened and heard the same differences we were told it was all in our heads because the components "couldn't" sound different.

My answer to that was always if we hear a difference that you can't measure it the answer is not that the difference does not exist but rather that you are measuring the wrong things.

Title: Re: VTA ST-70
Post by: Brap on January 25, 2017, 09:30:03 AM
Astute explanation for sure. Finished the build and bias all dialed in. Initially EL-34 sound has decent low end on my spare Paradigm Studio 10V.5's. Once I get some hours and this thing opens up a bit, will compare to the same amp I built 3 years ago with KT-66's. Nice build and took my mind off a crappy work week last week!
Title: Re: VTA ST-70
Post by: topround on January 25, 2017, 01:21:14 PM
you should know better than listen to Mel :duh

If we hear a difference then it is real, no browbeater can deny what you know!
We all have ears, the guy with a degree in engineering still has the same ears as you and I.

Besides what are they measuring? Perhaps the sonic differences we hear can't be measured yet with the equipment we have at hand. and no better gear than our ears!

Not trying to start an issue here, but just believe what you hear
Title: Re: VTA ST-70
Post by: Brap on January 31, 2017, 02:11:33 PM
So with about 25 hours of break-in, amp sounds pretty decent. Will change the rectifier to a Mullard GZ34 since I've read they tend to last much longer than the Chinese one with the kit. Zu Druids sound pretty nice.  Bias is staying quite steady with multiple power ups. Now the recipient of this beauty is looking for some speakers. Local shop in Chi-town (Holm audio) has some nice trade-ins. Will bring the amp in to audition a few sets. Recommendations are always welcome. Choices - LSA, Monitor audio, Vienna Acoustics and saw nice pair of Cornwalls for $1,200 (may be too large).
Title: Re: VTA ST-70
Post by: richidoo on January 31, 2017, 03:27:07 PM
DIY?   
http://www.humblehomemadehifi.com/Plutone.html
http://www.troelsgravesen.dk/8008-CORNER.htm

'Vintage' Legacy speakers have relatively good sensitivity, but low impedance dips in the bass are not great for small tube amps. But I liked it. Extremely satisfying, musical listening experience.

As for Cornwalls, the bigger the woofer, the better, imo. With low power tubes, it's wise to lean towards speaker types designed during that era, specifically for tube amps.

The world sorely needs a new, tube friendly, high sensitivity, large cone, high value speaker design, which incorporates the discoveries of the last 50 years.
Title: Re: VTA ST-70
Post by: StereoNut on February 01, 2017, 09:04:05 AM
... If we hear a difference then it is real, no browbeater can deny what you know... just believe what you hear.

TOP ROUND FOR PRESIDENT!!!
Title: Re: VTA ST-70
Post by: Brap on February 02, 2017, 07:08:59 AM
Thanks for the links. I'll check with my friend to see if he wants to take on the challenge. Funny coincidence -- I built the Joplin amp several years ago and it is still going strong.
Title: Re: VTA ST-70
Post by: richidoo on February 02, 2017, 08:32:17 AM
The DIY speaker from Bob Brines using TangBand W8-1772 driver is pretty good if funds are limited. But it's single driver, so the high treble beams strongly. I loved the sound of the floorstanding model but couldn't stand the beaming.
http://brinesacoustics.com/Pages/TangBand/Main.html

Transcendent Sound version is similar, but I never heard it.
http://www.transcendentsound.com/Full_Range.html
Title: Re: VTA ST-70
Post by: steve on March 21, 2017, 07:51:45 PM
I don't think it's weird at all. It is just more complicated that most people realize or at least are willing to admit.

Over my years in this hobby I have dealt with many measurement objectivists who would say that there was no difference between two components because the measured the same. And when a while bunch of us listened and heard the same differences we were told it was all in our heads because the components "couldn't" sound different.

My answer to that was always if we hear a difference that you can't measure it the answer is not that the difference does not exist but rather that you are measuring the wrong things.

Yep, got to be careful what forums you frequent and their agenda.

I have been permanently banned from another forum (positron moniker) while that forum still claims I am a "new member" with 26 posts. Over 1300 deleted though, so they lied about my status and sure did not have any problems with my posts for the past 13 years.

I was banned after I was asked to have any of my data "peer reviewed" by a gent and book author (both number guys). I replied that they only listed sight as a variable confound, and did not even mention cochlea fatigue. Why would I have them peer review my data? I was permanently banned by the next day.

You are certainly correct Tmazz, designing is much more complicated than the numbers people/engineers would have you believe. Although most are only taught numbers in college, don't be fooled, many of their comments are for marketing purposes.    

This forum is a good forum so we need to value it and help it grow if we can.

Cheers
Steve
Title: Re: VTA ST-70
Post by: tmazz on March 21, 2017, 09:31:56 PM
When I finished engineering school (EE) I bought myself a copy of the current ITT Radio Engineer's Handbook as a graduation present. One of the most humbling experiences of my life was the first time I opened that book and realized how much I hadn't learned in college.  :rofl:
Title: Re: VTA ST-70
Post by: Brap on March 22, 2017, 05:38:14 AM
While I was building a Transcendent OTL 2 years ago and a VTA-70 this past January, I took out my old EE text books from college just for fun to calculate some values in the circuits from the above.  Cant believe some of the notes on the pages were MINE and how much I forgot!
Title: Re: VTA ST-70
Post by: steve on March 22, 2017, 07:32:06 AM
Quote
While I was building a Transcendent OTL 2 years ago and a VTA-70 this past January, I took out my old EE text books from college just for fun to calculate some values in the circuits from the above.  Cant believe some of the notes on the pages were MINE and how much I forgot!
Quote
When I finished engineering school (EE) I bought myself a copy of the current ITT Radio Engineer's Handbook as a graduation present. One of the most humbling experiences of my life was the first time I opened that book and realized how much I hadn't learned in college.  ROFLMAO

My apologies Gentlemen as I did not know you had EE degrees.
I assumed what I should not have.

Fortunately, the public still can benefit from my mistake by our posts.

Cheers and again my apology.
Steve
Title: Re: VTA ST-70
Post by: Brap on March 22, 2017, 07:39:42 AM
No apology required!
Title: Re: VTA ST-70
Post by: richidoo on March 22, 2017, 08:04:28 AM
Subjective audiophiles are more like scientists, with open minds, heightened perception, willing to allow whatever they observe, excited and fun to note new observations. They believe in the unknown and fund their own experiments to explore it. Science never concludes, and there is never, ever a "scientific consensus." If there's a consensus then it's not science. A consensus like "cables don't matter," "feedback phase doesn't matter," "audiophiles are fools."  A consensus closes the discussion. It says that because most people whose opinion is judged by the bureaucracy to be valid agree that the world is flat or witches must burn then that is truth. Of course it isn't truth and that proves consensus is just closed minded religious belief.

Engineers and their closed-minded followers make these judgmental statements all the time. They work on problems using the consensus knowledge that is agreed by everyone in their field to be true. They are solving problems using the tools allowed by the system. They must work within the consensus even if it's not true. A person who can function in this world must be able to shut off the truth gene and just get 'er done without caring about truth. After 30 years of habitually filtering out scientific wonder they become incapable of using that muscle even if they want to. So they resist and become cemented to the old way of thinking and ignored by open minded scientific minds who look to the future and learning new things.

Most audio equipment is designed by engineer types, because the subjective audiophiles who contract them do not possess the engineering tools needed to make the stuff themselves. A combination of open minded visionary management and moneymen with scientists possessing engineering skills makes the best audio gear, or any other product for that matter. This is where you get the society changing products.  With a culture of open minded discovery, nothing is too crazy to consider, close minded dogma is rejected. Human resources is the hardest working department in the company.
Title: Re: VTA ST-70
Post by: rollo on March 22, 2017, 08:57:07 AM
  Well written Richidoo.


charles
Title: Re: VTA ST-70
Post by: steve on March 22, 2017, 04:28:34 PM
By the way, there is a large group of "engineers" that work together at what used to be Hydrogen Audio forums, maybe it still exists, and who are affiliated with a large corporation. They are heavily involved in attempting to shape the audio public's opinions.

They tend to spread out to various forums. I have dealt directly with them in the past, as I have previously posted in other forums at AN, and I have recently found a few more in the past year. If anyone is interested they can PM me for their names.

Cheers
Steve
Title: Re: VTA ST-70
Post by: steve on March 23, 2017, 09:30:22 AM
By the way, there is a large group of "engineers" that work together at what used to be Hydrogen Audio forums, maybe it still exists, and who are affiliated with a large corporation. They are heavily involved in attempting to shape the audio public's opinions.

They tend to spread out to various forums. I have dealt directly with them in the past, as I have previously posted in other forums at AN, and I have recently found a few more in the past year. If anyone is interested they can PM me for their names.

Cheers
Steve

Forgot to add that I found out that one or more in the group have patents, thus royalties; so a vested financial interest in the numbers only position rather than the honesty and learning mode that Rich described in his fine post.

As an example of vested interests, several of these numbers/"scientific" guys provided false information about study setups etc. to discredit the study. As one example, one PhD claimed headphone use (so bone conduction) when super tweeters were actually used some 8 feet away.

Cheers
Steve
Title: Re: VTA ST-70
Post by: rollo on March 26, 2017, 04:58:46 PM
By the way, there is a large group of "engineers" that work together at what used to be Hydrogen Audio forums, maybe it still exists, and who are affiliated with a large corporation. They are heavily involved in attempting to shape the audio public's opinions.

They tend to spread out to various forums. I have dealt directly with them in the past, as I have previously posted in other forums at AN, and I have recently found a few more in the past year. If anyone is interested they can PM me for their names.

Cheers
Steve

Forgot to add that I found out that one or more in the group have patents, thus royalties; so a vested financial interest in the numbers only position rather than the honesty and learning mode that Rich described in his fine post.

As an example of vested interests, several of these numbers/"scientific" guys provided false information about study setups etc. to discredit the study. As one example, one PhD claimed headphone use (so bone conduction) when super tweeters were actually used some 8 feet away.

Cheers
Steve

  Can you say GLOBAL WARMING. Not in agreement, then NO FUNDING, Hmmm scientists eh.


charles
Title: Re: VTA ST-70
Post by: steve on March 27, 2017, 09:44:16 PM
By the way, there is a large group of "engineers" that work together at what used to be Hydrogen Audio forums, maybe it still exists, and who are affiliated with a large corporation. They are heavily involved in attempting to shape the audio public's opinions.

They tend to spread out to various forums. I have dealt directly with them in the past, as I have previously posted in other forums at AN, and I have recently found a few more in the past year. If anyone is interested they can PM me for their names.

Cheers
Steve

Forgot to add that I found out that one or more in the group have patents, thus royalties; so a vested financial interest in the numbers only position rather than the honesty and learning mode that Rich described in his fine post.

As an example of vested interests, several of these numbers/"scientific" guys provided false information about study setups etc. to discredit the study. As one example, one PhD claimed headphone use (so bone conduction) when super tweeters were actually used some 8 feet away.

Cheers
Steve

  Can you say GLOBAL WARMING. Not in agreement, then NO FUNDING, Hmmm scientists eh.


charles

Maybe it is late, but I don't understand your point.

Cheers
Steve
Title: Re: VTA ST-70
Post by: dBe on July 26, 2017, 07:56:22 PM
Subjective audiophiles are more like scientists, with open minds, heightened perception, willing to allow whatever they observe, excited and fun to note new observations. They believe in the unknown and fund their own experiments to explore it. Science never concludes, and there is never, ever a "scientific consensus." If there's a consensus then it's not science. A consensus like "cables don't matter," "feedback phase doesn't matter," "audiophiles are fools."  A consensus closes the discussion. It says that because most people whose opinion is judged by the bureaucracy to be valid agree that the world is flat or witches must burn then that is truth. Of course it isn't truth and that proves consensus is just closed minded religious belief.

Engineers and their closed-minded followers make these judgmental statements all the time. They work on problems using the consensus knowledge that is agreed by everyone in their field to be true. They are solving problems using the tools allowed by the system. They must work within the consensus even if it's not true. A person who can function in this world must be able to shut off the truth gene and just get 'er done without caring about truth. After 30 years of habitually filtering out scientific wonder they become incapable of using that muscle even if they want to. So they resist and become cemented to the old way of thinking and ignored by open minded scientific minds who look to the future and learning new things.

Most audio equipment is designed by engineer types, because the subjective audiophiles who contract them do not possess the engineering tools needed to make the stuff themselves. A combination of open minded visionary management and moneymen with scientists possessing engineering skills makes the best audio gear, or any other product for that matter. This is where you get the society changing products.  With a culture of open minded discovery, nothing is too crazy to consider, close minded dogma is rejected. Human resources is the hardest working department in the company.
Wow!  That kind of talk is part of what got me banned from another Forum!  Cool...  :thumb:
Title: Re: VTA ST-70
Post by: Nick B on July 26, 2017, 08:16:22 PM
Subjective audiophiles are more like scientists, with open minds, heightened perception, willing to allow whatever they observe, excited and fun to note new observations. They believe in the unknown and fund their own experiments to explore it. Science never concludes, and there is never, ever a "scientific consensus." If there's a consensus then it's not science. A consensus like "cables don't matter," "feedback phase doesn't matter," "audiophiles are fools."  A consensus closes the discussion. It says that because most people whose opinion is judged by the bureaucracy to be valid agree that the world is flat or witches must burn then that is truth. Of course it isn't truth and that proves consensus is just closed minded religious belief.

Engineers and their closed-minded followers make these judgmental statements all the time. They work on problems using the consensus knowledge that is agreed by everyone in their field to be true. They are solving problems using the tools allowed by the system. They must work within the consensus even if it's not true. A person who can function in this world must be able to shut off the truth gene and just get 'er done without caring about truth. After 30 years of habitually filtering out scientific wonder they become incapable of using that muscle even if they want to. So they resist and become cemented to the old way of thinking and ignored by open minded scientific minds who look to the future and learning new things.

Most audio equipment is designed by engineer types, because the subjective audiophiles who contract them do not possess the engineering tools needed to make the stuff themselves. A combination of open minded visionary management and moneymen with scientists possessing engineering skills makes the best audio gear, or any other product for that matter. This is where you get the society changing products.  With a culture of open minded discovery, nothing is too crazy to consider, close minded dogma is rejected. Human resources is the hardest working department in the company.
Wow!  That kind of talk is part of what got me banned from another Forum!  Cool...  :thumb:


That's a wonderful synopsis. Glad I was able to come across it.
Nick
Title: Re: VTA ST-70
Post by: djdube525 on July 27, 2017, 03:44:09 AM
I have found people's "beliefs" and "what they know to be true" are rooted in their frame of reference.

Much of the industry (and this is true for many industries, not just audio) it seems is rooted in incremental improvements. Could be feature enhancements, or cost reductions... but "new things" drive the economy.

The societal changing events seems to come from people outside the industry who have an idea. Even though there were some audio devices with meager amounts of flash storage, when Tony Fadell came to Steve Jobs about a music player that you can hold in your hand with 10G of music... and then when Apple introduced SW to make it easy to add music to the device (saw what you want about iTunes... it was a bit of a pain for the "average joe" before then. And now people pretty much have instant access to more content then is comprehensibly imagined from a computer, phone, or even a $35 mini computer (RPI).

I still remember the day my father handed my mother ("technophobe" would be an understated description of my mother) an iPad that had access to all their connected devices and all their ripped music, and she could play anything with a couple taps, and my father no longer had to "come up stairs to turn on the stereo and play a CD".... not to be over the top, but it was a bit life changing for both of them

But I digress...



How's the ST-70 build coming??? Inquiring minds want to know. :)
Title: Re: VTA ST-70
Post by: rollo on July 27, 2017, 08:00:15 AM
Hey Brap good to see you here again. Did not know you could build. So cool to have that knowledge and skill. Will be following your build.



charles