• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Which amp to trade for Dynaco ST70 or VTL ST80?

petercapo said:
And they would provide such documentation for it?
Click to expand...
Once I experienced failure of an output coupling cap on one of my MB-450s. I emailed Bea and she helped me diagnose the trouble and sent me a replacement.

That's the nice thing about working with non-defunct companies. Are you familiar with them? They continue to manufacture some of the best tube amplifiers available. Bea personally auditions every one before it leaves the factory.

 
petercapo said:
The Dynacos were heavily marketed to DIYers from the start, so there is no surprise that they have been a favorite to dive into and change things.
Click to expand...
That and the fact they cost $100 when introduced in '59 or so! You can only achieve that using inexpensive parts like carbon resistors, ceramic caps, comparatively small power supplies, etc. There was lots of room for improvement!

I built an FM-5 and a PAT-5 in my teens during the mid 70s. The preamp was later modified by Frank Van Alstine where I first learned of Dale RN60 metal film resistors, tantalum and polystyrene caps, etc. Following his lead with the external power supply on the Double Dyna 400, I added another 60,000 uF (and a 30A bridge) to an Audire One in 1976. Boy, that sure improved transparency and dynamic punch.

Companies like VTL got that from day one. Each 450 has a 250 joule power supply. :)
 
Any of those voting for the VTL ST80 got a schematic or underside pics to show here? And does VTL offer after sales support to second owners? Just asking, as I've never seen one of these.
 
Thank you all for the replies.

To be clear. My primary concern is getting the best trade possible for my gear. The Dynaco seems like it will be a no brainer if/when I get the itch for something new. The market is strong for them. I just don't have any experience with the VTL amp and I don't see much in the way of sales history to know if it is a good investment. I don't actively flip gear but I will listen to it and enjoy until something better comes along. I like my hobbies to at least be self supporting.

The Dynaco ST-70 is basically stock. The driver board is original. Not sure about the power supply yet. I would think that it would have to have new caps and diodes at a minimum. I did see that it has a 5R4 rectifier tube instead of the 5AR4.

The VTL is supposed to have been recently serviced with new tubes and biasing.

I think the VTL does not have multiple taps. At least the info I have read about the ST-85 states that the outputs only have the one winding for approximately 5 ohms.

The Craftsmen speakers I have are 16 ohms and use the 2640TX drivers. They would be best paired with the Dynaco. I do need to redo the cloth surrounds. The goop migrated to the bottom of the drivers and has hardened.

The only speakers I have that would be close to a 5 ohm load would be the Infinity RS 1.5s. I did power them with a Pioneer SM-c800 I have. They sounded really good with that amp. I have had the Infinities for more than 20 years and listen to them daily.

Most of the speakers and receivers I have posted in Bartertown have been in rotation for several years.

I will reach out to VTL to see if I can at least get a brochure or other info so that I can make an educated decision.

I also have a Yamaha PS-2200 on the way. I'm thinking it will pair well with the NS-200Ms.

Not sure about the Tannoys. I think they need a better enclosure but will try them with both amps.
 
E-Stat said:
Once I experienced failure of an output coupling cap on one of my MB-450s. I emailed Bea and she helped me diagnose the trouble and sent me a replacement.

That's the nice thing about working with non-defunct companies. Are you familiar with them? They continue to manufacture some of the best tube amplifiers available. Bea personally auditions every one before it leaves the factory.

Click to expand...

That video is very impressive. Thank you for sharing it. I had no idea.
 
E-Stat said:
Click here for their contact information.
Click to expand...
From the video, VTL looks to be a good small company, making high quality products. I'm not in the market for one, but still wondering if schematics of their older products are available, and whether they support such units when sold on by the original purchasers.
 
Last edited:
petercapo said:
This is not to say which amp @Potato_Head would prefer the sound of, all things being equal. But, a few things should be said, again if necessary. For instance, decades old Dynacos can have their parts refreshed 1:1 with the same "quality" of parts that VTL and other amps use. This is one of the problems with buying any older amplifier, including an older VTL amp that could very well need parts refreshing to be at its best.

The concern I often express is that someone will take a fifty year old sample of a Stereo 70 that needs a nursing home, and compare it to something having the advantage of newer parts quality, and inevitably decides the Stereo 70 can never be better than a relic from a bygone age. The Stereo 70 never had a chance. A valid comparison begins on a level playing field, but a half-century old amp usually doesn't have this luxury.

An upgraded power transformer for the Stereo 70 is also available. A good quality 5AR4 works fine in the Stereo 70 unless you try to pass 20Hz at full power - not likely in ordinary use - see Dave Gillespie's test results, here: http://www.audioregenesis.com/documents/ST-70 Base Line Testing.pdf The old phenolic circuit board in the Dynacos can be challenging, but with the right touch they can still be usable. If not, new FR4 copies are readily available, and, yes, they can be stuffed with the latest 1% metal film resistors and polypropylene capacitors. Beefing up the power supply is possible with either the upgraded quad section can, or adding discrete electrolytics under-chassis, or using a cap board.

I am not trying to say the original Stereo 70 is a perfect amp, but it's perceived faults should be put into a realistic context and not exaggerated. They can be refreshed with the same parts quality that much more expensive amps now enjoy. The original Dynaco started in the mid-1950s and went out of business around 1980, and the longevity of their original tube designs is manifestly obvious today, and there is more readily available, free support for the Dynacos than you'd likely get with most other brands.
Click to expand...

Not disagreeing with your content except to qualify the last Part.
I think it's pretty safe to say there is more support and part availability (by a far margin!) For the st70. I think "all " rather than "most".
Sorry for the nitpick (I am agreeing with you:thumbsup:)
 
One other side note.
Only because I have a restored st70 , I might choose the vtl. Not based on anything other than I'm a sucker for a new amp (read as different, not necessarily more modern).
 
If it were my choice, I would go for the VTL, I would think they are worth more than the Dynaco, as they are not as common, it would always be easy to get a Dynaco later.
The power supply would likely be better in the VTL, and it dosen't use the 7199 tube also.

Edit:
After looking at pics, VTL only having one impedance tap, and the Dynaco looks better, I'm not sure any more
 
Last edited:
petercapo said:
Some audiophiles still prefer carbon comp today, and ceramic capacitors are still appropriate for certain positions in the circuit.
Click to expand...
Really? You won't find any such in VTL or Audio Research models. Both use WIMA film caps for bypass duty and strictly low noise metal film resistors.

petercapo said:
In any case, you can add tens of thousands of microfarads to a solid state amp, but it usually isn't an option for tube amps even today. Some feel that large amounts of capacitance in a tube amp power supply is undesirable.
Click to expand...
As joules are exponentially related to voltage, you don't need "tens of thousands" for a stiff supply. Mine uses 1650 uF @ 550V for 250 joules. I'll never forget hearing a pair of Siegfrieds (like you find in VTL's listening room) in an audio reviewer friend's phenomenal system. Those run 4950 uF for 750 joules. To each his own!

petercapo said:
IHe has long decried the audiophile penchant for parts upgrades, because he believes that the "magic" comes from the circuit topology, not boutique parts.
Click to expand...
Companies like VTL and Audio Research simply choose the highest quality, best sounding parts they can find. Here's another set of factory tour videos you might enjoy.


 
Last edited:
Dandy said:
Unfortunately, without pics of the VTL amp under discussion and, even better, a schematic, there's not a lot more to discuss. Maybe the OP will give a listening report?
Click to expand...
With all of the comments this post has generated, I will have to do a good follow up review of both the amps and my thoughts about them! I hope to have both of them on Thursday of this week.

I am going to have to up my game as far as the preamp is concerned.
 
I have had several Dynaco St70's (stock,slightly modified,and heavily modified) and if I had the option, I would go with the VTL.
I know just how much can be had with the Dynaco, and would rather try a more ''modern'' design just for fun.

Keep in mind,I am an experienced tech,so the following has no bearing on my decision;):

Manley amplifiers have a good reputation for build quality,sonics and reliability. That said,I have also read many (irate) posts about the companys unwillingness to provide any service information/documentation whatsoever,and if you are not the original owner,go f*** yourself seems to be their business model.Caveat emptor and all that.....
 
You must log in or register to reply here.
Back
Top Bottom