VTA ST-70 Review (Stereo Tube Amplifier)

[Ralph_Cramden]

I love vintage gear from that era… Eons ago I found a very nice Scott 299A amp and 350B tuner to restore. Scott gear was popular on Audio Asylum at the time (where I used to hang out 20+ years ago). Unfortunately I never got to it and ended up reselling it unrestored… :-(

View attachment 196361
View attachment 196362

I briefly owned the chocolate version of this set (LK-72), with nice walnut cases many years ago. Did not "get" toobz, at all, lol.

 

[dfuller]

The original design used an input pentode coupled to a less-than-unity-gain cathodyne phase splitter. If this is indeed a variant of Mullard, the phase splitter will be a long tail pair with gain, but not enough to equal the original circuit's. The original Mullard circuit used a pentode up front with the long tail pair, so had oodles of open loop gain for distortion and source impedance reduction.

Hmm, if it's an LTP and a pentode input it seems like there would be plenty of gain on hand for feedback.

 

[SIY]

Hmm, if it's an LTP and a pentode input it seems like there would be plenty of gain on hand for feedback.

That’s the original Mullard. This one uses a relatively low gain triode instead.

 

[TLEDDY]

I still listen to one (updated by my friend, Randy) from time to time on Quad 63s and Kef LS 50s. Noting my hearing stops at about 9500 Hz, I still enjoy the experience.

Of those who cast votes, how many actually own or have owned an ST-70?

 

[pseudoid]

I really wanted to like this ST-70 because I've always had a fondness for my original-issue McIntosh MC275.
If I was a gambling man in the hunt for a tube amp, I'd wager $2,500 on this knock-off:

 

[Doodski]

I still listen to one (updated by my friend, Randy) from time to time on Quad 63s and Kef LS 50s. Noting my hearing stops at about 9500 Hz, I still enjoy the experience.

Of those who cast votes, how many actually own or have owned an ST-70?

I have never owned one and I voted a, "Fine, Happy Panther" level because it's so old and still works pretty good. As the toob geeks here say it needs different toobs to realize it's full potential and I considered that too.

EDIT: @amirm clarified the matter and this specific amp is ~2-3 years old. It's not old.

 

[Chrispy]

Just can't imagine spending that kind of money on something like this.

 

[jam]

Thanks for an interesting tube amp review Amir, which we don't see too many of. Loads of distorsion, only 12 bits of resolution at best, relatively low power before if gets nasty, plus you have to deal with the tube lifetime and fiddle with the bias adjustment. This one is not for me.

 

[amper42]

These measurement make the Hegel H95 look great... lol.

 

[nyxnyxnyx]

Is there a chance of quality deterioration when you measure it?
For example, what if we we measure a very, very vintage piece that has been around for decades. Is there a chance that we will not get the same measurements we were supposed to in it's original state?
Would be great if someone can explain this aspect to me.

 

[Doodski]

Just can't imagine spending that kind of money on something like this.

It's a historic component that is pretty much a guaranteed winning horse in the appreciating in value aspect. I would spend the bucks if I wanted a vintage antique toob amp. That Sherwood sort of stuff that I posted earlier in this thread is selling for up to $2700. When I bought mine I paid $200.00 in the early 90's.

 

[olderman]

What is up with these connector sort of things on the front panel. Are these pre-outs or only for bias adjustment?
View attachment 196360

Those are standard tube sockets. How or if they're connected, I have no idea.

 

[amirm]

For example, what if we we measure a very, very vintage piece that has been around for decades. Is there a chance that we will not get the same measurements we were supposed to in it's original state?

To be clear, this is a modern design around old tubes. I think the unit is only 2 to 3 years old.

 

[amirm]

Those are standard tube sockets. How or if they're connected, I have no idea.

They are connected with two pins to measure bias for each tube pair. I think it was just convenient to use a tube socket for it than something else.

 

[whyfi]

My guitar would probably sound nice through this thing.

 

[pseudoid]

Tubes that are included are: NOS Mullard EL-34's and a NOS Brimar CV4003/12AU7 and new production Prima Luna 12AU7s.

To be clear, this is a modern design around old tubes.

NOS = New [but] Old Stock

 

[JDS]

What is up with these connector sort of things on the front panel. Are these pre-outs or only for bias adjustment?
View attachment 196360

I believe those sockets were used to plug in an umbilical cord that was used to power a (pair of) Dyna pre-amps.

 

[sam_adams]

I really wanted to like this ST-70 because I've always had a fondness for my original-issue McIntosh MC275.
If I was a gambling man in the hunt for a tube amp, I'd wager $2,500 on this knock-off:View attachment 196383
View attachment 196385

$1700 Quatloos plus $550 shipping. They barely made an attempt to obscure the the 'McI' in this knockoff at around $2300 + $612 shipping.

 

[pseudoid]

They barely made an attempt to obscure the the 'McI' in this knockoff at around $2300 + $612 shipping.

Why bother, if the design is a proven one, yet updated?
ST-70 attempts to achieve the same old/new conundrum but fails more (imo).

 

[Chrispy]

These measurement make the Hegel H95 look great... lol.

Makes almost anything else look great