Poor man's tube system?

[bbqjoe]

I built and use a VTA-70. It's a great kit. The instructions are very good. You just have to carefully follow them. Depending on options they will ask to jump to instruction # etc. And support is great. As for the model 14 preamp the instructions are basic. Basically a schematic and a drawing. Roy expects you to know what your doing.

I would assume you're happy with the whole thing?

 

[Lavane]

Yes. I am very happy with the ST-70. The only problem I've had was with a new old stock driver tube that was failing.

 

[bbqjoe]

Yes. I am very happy with the ST-70. The only problem I've had was with a new old stock driver tube that was failing.

Well, tubes is tubes, and there's always a chance of anything having a margin of failure rate.
Do you find the power/volume enough, or do you find you wish you had a little more?
Of course the other option is to consider the M125 mono blocks at a bit steeper price.

Edited to add.
I just saw that you are talking about the 70.

 

[Lavane]

The speaker sets I'm using are 95db or better, so the 35wpc is plenty. The mono blocks are nice since you can use just two output tubes per channel if you want. 60wpc with two. If you think you need more you can add two more per channel.

 

[eickmewg]

Any of the Latino VTA amps, ST 70, ST 120, or M125's would be a nice choice. Very easy to build with excellent performance. I would recommend the ST 120 with an octal driver board and without tubes. Then talk to Jim McShane about the tubes you want to start with. I doubt you will be disappointed. But then the monoblocks would be nice too. I have Polk SDS speakers that require a common ground and that meant no monoblocks unless I got the special A1 interconnect cable.

 

[tubeactive]

Hey bbqjoe, Your listening room is 750 sq. ft. ? That is a very large room. Without big, efficient speakers, I believe you need as much power as you can afford.

I used to run my Large Advents (87-88 db/w/m in a much smaller room with Dukane 1A475C 120Watt Monoblocks. You should have heard the 1812 Overture with that system. Perhaps the "biggest sound" from those speakers, with AR9 (250 watt rated) woofers BTW, came from two Altec 1570BT 165 Watt Triode amps. Vintage amps with retro-resto mods can compete with anything.

I do believe the kit amps are "right up your alley" since you have familiarized with electronics before. Anyway, big rooms need big power, unless you have big speakers, like Altec Voice of the Theater stuff....

 

[bbqjoe]

I haven't pulled the trigger yet, but after looking over the site for a few days, I'm going to go for upgrades right off the bat so as not to have to go back later and do them.
So I'll go with the higher end caps and the gold lion tubes etc.
I'm still looking at the model 14 preamp, and also came to realize that the ST120 can be ordered with an attenuator, and appears to have its own preamp.
So other than the ability to switch input components, how much more love will a separate preamp add?
Is the one in the amp just not good, or not good enough?

Eventually my room will actually get smaller one day after I build onto the house and add a music room.

 

[tubeactive]

Well, with your interest, desire to achieve and abilities, I am sure you will persevere within the tube amp realms. Work within your means and with practicality in mind. With a very large room, you can still use the room boundaries and walls to your advantage.

Acoustically, walls are not just boundaries; they can be utilized as sound directors, even extensions of acoustical corner horns. Every wall, floor or corner boundary helps to add to speaker box resonance. Coupled to a nearby wall, bass resonance is enriched by nearly 2 db. Couple to an actual corner, bass rez easily increases over 3 db. However, too much bass rez can sound boomy. Compromises and positioning is in order. Tilting or angling the speaker toward the listening area can be adjusted to your liking, also.

With a huge room like yours, I would consider using a corner as the equipment setup area. Position the speakers near and along each side of the new, corner equipment unit, using the angled side walls to "project" and direct the stereo sound into the vast area. Essentially, you will be creating a stage and theater, using the V-shaped side walls to set some boundary for your stereo image soundstage efx....
Good Luck and ENJOY !

 

[bbqjoe]

Well, with your interest, desire to achieve and abilities, I am sure you will persevere within the tube amp realms. Work within your means and with practicality in mind. With a very large room, you can still use the room boundaries and walls to your advantage.

Acoustically, walls are not just boundaries; they can be utilized as sound directors, even extensions of acoustical corner horns. Every wall, floor or corner boundary helps to add to speaker box resonance. Coupled to a nearby wall, bass resonance is enriched by nearly 2 db. Couple to an actual corner, bass rez easily increases over 3 db. However, too much bass rez can sound boomy. Compromises and positioning is in order. Tilting or angling the speaker toward the listening area can be adjusted to your liking, also.

With a huge room like yours, I would consider using a corner as the equipment setup area. Position the speakers near and along each side of the new, corner equipment unit, using the angled side walls to "project" and direct the stereo sound into the vast area. Essentially, you will be creating a stage and theater, using the V-shaped side walls to set some boundary for your stereo image soundstage efx....
Good Luck and ENJOY !

Pulled the trigger. St-120 has legs, and is headed my way!
Short story.
We are completely off grid, and live in the middle of nowhere.
As I mentioned previously, the construction is bare painted block walls. With windows and doors of course.
This was to be the first part of the house (bedroom), with an addition to follow shortly after.
One thing led to another, and it turned into a giant open efficiency.
At this point, not much is changeable as far as the layout goes, so this is what I have to work with.

The 301's are up on the walls at about 8 foot, with an 11 foot ceiling.
The DQ's sit about mid ear level.
The only thing I could probably change is to switch the long desk, and the dresser by my desk, put the stereo on the small dresser, and the speakers on the floor. TV is mounted on the wall.

Things will change at some point as we are preparing to put the 1200 sq. ft addition on, but that's gonna take time as the wife and I will most likely build it ourselves, such as we did this first part.

The proportions are close, but not not perfect.

 

[primosounds]

View attachment 1357280

Pulled the trigger. St-120 has legs, and is headed my way!
Short story.
We are completely off grid, and live in the middle of nowhere.
As I mentioned previously, the construction is bare painted block walls. With windows and doors of course.
This was to be the first part of the house (bedroom), with an addition to follow shortly after.
One thing led to another, and it turned into a giant open efficiency.
At this point, not much is changeable as far as the layout goes, so this is what I have to work with.

The 301's are up on the walls at about 8 foot, with an 11 foot ceiling.
The DQ's sit about mid ear level.
The only thing I could probably change is to switch the long desk, and the dresser by my desk, put the stereo on the small dresser, and the speakers on the floor. TV is mounted on the wall.

Things will change at some point as we are preparing to put the 1200 sq. ft addition on, but that's gonna take time as the wife and I will most likely build it ourselves, such as we did this first part.

The proportions are close, but not not perfect.

One needs to be careful about speaker placement and type especially in a room where the walls are cement or hollow tile. The highly reflective nature of those surfaces bounces the sound easily which disrupts the soundstage from the speakers and can cause frequency anomolies. Speakers that are placed close to the wall will also have reflections. The reflection off the back wall needs to be broken up with sound adsorbing material or heavy drapes, something like that. Professional sound installation techs have various instruments to help with this stuff but if you can read up on the subject you should get a good idea of how to improve your listening area. Of course, a lot of people don't really care that much about it but if you seriously like listening to audio then speaker placement and room improvements can make a huge difference.

 

[bbqjoe]

I built my first real tube amp.
Bob's VTA St-120.
I had a few minor setbacks, but all in all this was a fun build, and it sounds fantastic!

I no longer have a poor man's tube setup!
Next up is Roy's SP-14 preamp!

 

[eickmewg]

Nice job, Joe. Enjoy your VTA ST-120!

 

[bbqjoe]

Nice job, Joe. Enjoy your VTA ST-120!

Thank you!

 

[ddrjboo]

Hi bbqjoe! Nice work on the VTA ST-120. I finished building mine and fried the rectifier tube after setting the bias on the output tubes. I must say your wire twisting and routing look better that what I did. And good luck with your Wharfedales!

 

[bbqjoe]

Hi bbqjoe! Nice work on the VTA ST-120. I finished building mine and fried the rectifier tube after setting the bias on the output tubes. I must say your wire twisting and routing look better that what I did. And good luck with your Wharfedales!

Hey thanks!
I think I could do even better if I had to do it again now that I understand the hows and whys of this amp.
Sorry to hear about your rectumfryer.

I decided to go with all the bells and whistles; upgraded caps, tubes, weber rectifier copper cap, and the TDR mod. Knowing myself, I know I would spend the rest of my days wondering, if I hadn't just gone and done those things right off the bat.

But don't feel bad, I think most everyone is apt to have a screwup, at least the first time.

I had mine all together, and ran ran it for about 6 hours until I was satisfied it wouldn't go nuclear.

I took it back to the shop, finished cleaning it, then tie wrapped.
When I took it back into the house, I turned it on, let out a little light and some smoke.
While cleaning I broke a wire on the pentode switch and didn't see it.
It arced 500 volts to the switch and the resistor. Both were fried.
I had to wait for Bob to mail some new ones.
While I waited it gave me time to reflect on my work, and caused me to rework some stuff I should never have accepted from myself.

All is good now, and I just love this amp!

if he ever comes out with a 300 watt monster, I'll be first in line!