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LTusler

New VTA ST-70

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I built this amp Kit from Bob Latino last weekend.  So far is sounds great!  For break in I am using:

Turntable/CD Changer>Shitt SYS>VTA ST-70> Hersey 1's with Crites Mods.

Amp Small.jpg

Amp Wired Small.jpg

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I am in the process of building the exact same amp as we speak!  Should be done tonight or tomorrow.  Lots of fun to build, and I can't wait to hear what it sounds like.  I will test it out on my Crites-modded Heresys before it gets hooked up to my main speakers.

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Here is a review of my process:

 

The kit,

I came very well packaged in one box.  Very quick shipping

Everything was well labeled and all of the electric components were in separate zip lock bags.

The instructions were about 10 pages plus a couple pages depending on the options you choose.

A high resolution color photo and color diagram of the point to point wiring are included.

 

Mechanical assembly,

Pretty straight forward.

Have good lighting and a clean counter space about 3' wide and 2' deep.

A lazy Susan would be helpful.

If you're right handed place the soldering station on your right and the solder on the left.

Do not attempt to out think the directions!  Follow them to the letter and in order, it will all make sense in the end.

There are many short small screws and nuts.

Pick a direction to face all of the screw slots.

Some pre-soldering is done to make things easier in later steps.

Chuck wire pairs in a variable speed drill to twist, go slow and keep some backward tension as it twists.

 

Electrical assembly,

Wide tip soldering iron for most of the point to point wiring works well, a small pencil tip for the circuit board is required.

Load the resistors and caps by the instructions and bag, DOUBLE check your part orientation and part location and the solder and flush cut excess.

When using an auto stripper on the supplied 20 ga. wire, bend the pieces in half to avoid pulling the wire sheath as it strips.

Route and bend the point to point wiring so that it lays in place before soldering.

Don't know if it matters, but I wore a cotton glove when inserting the tubes.

 

Start up,

Again follow the instructions.

I did have 2 wiring errors and 1 missed solder connection.

I ordered the attenuator kit, so for start up I just plugged in a CD player and a pair of speakers then started playing music.

I've been running it for a couple hours each day and cooling it down to heat cycle it before putting the bottom on just to make sure everything stays in place, I will recheck the screws and then button it up and insert into my main system.

The bias lowers as the amp heats up, so I adjust it after 5 min of power up, then just before power down, the variance gets smaller each time.

 

Conclusion,

Its my first tube amp, I am in love.

 

Main system,

NAS all FLAC, AT LP120 Modded Ortofon Blue, Sirius Internet> Sonos Connect> Cambridge DAC Magic Plus> MiniDSP DDRC88BM> VTA ST70> Cornscalla Type D

 

 

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What size room is this and the Heresies that it is pair with in?  I am curious to your thoughts on the sound with the Heresies.  I have a pair in a 10x9 room, but was thinking of a different route.

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Looks like he(Bob) has several options for output tubes. What did you go with?

Also on his website the chassis look like chrome and nice and shiny. Are you happy with yours?

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The Hersey's have Crites tweeters and caps.  The room is 24x30, I had them set up in one corner about 7' apart and 10' from the MLP for testing.  I thought the sound stage was nice with good bass response, I am not a big bass head.

 

I went with the stock set EL34's.  Since I'm a tube virgin, I wanted an upgrade path.

 

The base is polished SS, looks nice, but be careful it scratches pretty easily. 

 

I just moved it to the main system listed above, sounds nice so far on the Cornscalla's.

 

Putting on Van the Man, No Plan B.....

 

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I built the same amp last February and used the 6550 output tubes and it's a great sounding amp.  I ordered a couple spare GZ34 rectifier tubes  to be on the safe side and I believe I have a Ruby in there at the moment.  The front three tubes make the biggest difference with the center one being the most difference, it's said, and I bought a Genelec Gold Lion for that location.  I'm not a big tube roller and won't get any others till these either sound bad, won't bias, or just quit.  I can't hear any differences in them, personally. 

 

It's been a great amp and sounded awesome on the CF-3's I had and sounds awesome on my Belle clones as well.  It's about to be packed away for about 6 months or so as we just listed our house for sale so most all my gear is going into storage at my best friends house.  (Belle's, ST-70, Mac MC250, and some other gear)  At least I got to hear those combos for a couple of months before packing them up.  

 

Great amp and great job on the build!  I use the ST-70 as my pic on here.

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Thanks for the tube tips!  The link to your speakers is broken.  I would be interested in more information on your inspired Belle's.  My Cornscalla D's are a bit inspired as well.

20180108_170644.jpg

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Just got mine finished up last night.  Fired right up on the first try!  Played it for a couple hours on the Heresys to confirm function.  It was interesting playing with the pentode/triode switch.  To my ears, it sounded much better in pentode mode.  Much better bass and more balanced sound.  Triode mode was way too "midrange forward" for my taste, at least while playing rock and roll.  It will be interesting to hear the difference once I incorporate it into my main system as it will only be driving 500hz and up on my bi-amped mains (2" B&C drivers over La Scala bass bins).

IMG_2585.JPG

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Nice jobs by both of you.  These amps are a good value and Bob is a really good guy that knows his stuff.

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Hi @LTusler ... very nice job, especially on the wiring! Congrats! And @Tarheel TJ ... same; awesome! Got myself a kit for last Xmas :) and like it (with my Forte's). Not sure it is any better than the Marantz it replaced, but the tubes are not "burned in yet. (Have been playing in my TV room with new AVR's, amps and KPT904's :) )

 

Here's mine :) 

 

IMG_2080.JPG

 

Cheers, Emile

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On 3/15/2018 at 10:20 AM, LTusler said:

Here is a review of my process

Very good review. Lots of GREAT tips for prospective builders ... wish I had those tips 3 months ago :) 

Cheers, Emile

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On 3/16/2018 at 8:59 AM, LTusler said:

Thanks for the tube tips!  The link to your speakers is broken.  I would be interested in more information on your inspired Belle's.  My Cornscalla D's are a bit inspired as well.

 

 

Link fixed.  Thanks for the heads up on that.

 

I guess they all look about the same once completed but here's mine, too.

 

[âIMG]

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Glad to see I'm in good company.  Anyone else have thoughts on triode vs. pentode operation?  I will be using mine with a MiniDSP in the main system, so I should be able to EQ it flat regardless.  Just wanted to hear everyone's impressions of the sonic differences between the two modes.

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I haven't had enough alone time with to say yet.  I went to see Claire Lynch in Minneapolis on Tuesday.  Very small venue, looks like it was set up for about 120 people, and was about half full.  She has an excellent stand up bass player, so I tried to burn the excellent sound into my brain and will test it against my system this weekend.

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Thanks.   I bought her current CD, it has some of the same songs we heard, so that will help too.

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So I just bought a brand new VTA ST 70 fully assembled and have about 2 hrs on it so far.  I got the volume control so right now I'm using it without a pre amp.  Right now I'm using it with a pair of Lascalas and the clarity and detail are a major step up from where I've been.  I am a little disappointed with the bass so far, do I need more hours on the tubes to break in?   Bob suggested the el34's for heritage speakers so that's what I went with.  Any thoughts on that?     

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I have done some listening this weekend now that my ST-70 is in the main system (driving a 2” driver in a biamped configuration).  Since it now only plays from 500hz up, I have found the triode/pentode switch doesn’t make nearly as much difference.  In fact, I can barely tell the difference between the two.  Granted, I don’t have 100 hours on the amp yet, so nothing is fully broken in yet.

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So I bought an Emotiva PT-100 preamp and hooked my ST70 up to my Khorns which are in my basement in perfect corners but the floor is carpet over cement.   I still only have about 20 hrs on the amp but I have very little bass.  I've cranked up the bass adjustment and its still weak and totally not good enough.  

 

I hooked up my THTLP sub and of course it was great but I just can't believe my Khorns sound so bad without a sub.   Is it the cement floor?   Is it the preamp?   Is it the ST70?

 

I have the Khorns spaced 16ft apart in perfect corners and the room is 22 feet deep.  I really expected to be blown away and now I don't even want to listen to it without the sub on.  

 

 

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