Just ordered my first kit... 120

Nice to "meet" everyone,

Just ordered my first kit, I really like the idea of listening to my vinyl with something I built with my own 2 hands, In my case, I opted to go with the 120 with the attenuator and upgraded caps.

Looking forward to starting the build... but before I get into this, is there anything I need to know?

I admit I am a little nervous about building something this expensive, I've done some small kit building before (Some Heathkit radios when I was a kid, a budget Oscilloscope from Amazon etc) so soldering skills are not a problem (In fact compared to the normal soldering I usually do which is tiny SMD crap, this looks like fun) and I have a fairly grounded knowledge of Electronics in general so after talking with Bob (who spent a lot of time helping me choose ) I took the plunge.

Thanks in advance!

Welcome mcgyver!

Sounds like you are all set skill wise. Bob's kits come with exceptionally detailed instructions. You shouldn't have any trouble. Just don't rush and double check your work and you should be good. Use good old lead based solder.


Tim L.

Welcome to the club!! I built a VTA-70 about three years ago. Here's a link to my build:

VTA-70 Build

A good variable temp soldering station is a good idea. Read thru Bob's instructions before proceeding to familiarize yourself with the procedure. Work slowly and carefully. Dress wires cleanly. Bob is just a phone call or e-mail away!

Good luck and be prepared for outstanding sound!!

It's not a race, if you feel yourself getting tired, finish up making sure you can pickup where you left off the next day. I found myself continuing while I was tired, almost screwed up. Bob's kits are amazing, you will enjoy building it! Welcome and enjoy!

Welcome! Enjoy your build.. I put together 2 M125's a month or so back and couldn't be happier.

Thanks everyone, I keep watching my tracking number updates, excited to get started.

I already have a good soldering setup (Weller digital variable with a Hakko Fume extractor) so all good there,

How critical is the wire routing? The reason I ask is that i was planning to follow the instructions but I always like to see how I can make things neater and cleaner (When I was working as a car audio installer, I would take hours to route each cable as neat as possible so it was aesthetically good looking as well as functional) Now that I read some other posts I hear about Noise that was fixed by rerouting cables....

Guess I'll just follow the directions to the letter

I didn't follow the wiring routing pics for my M125's to the letter and they both came out dead quiet.

Jersey City? I grew up in Bayonne

mcgyver74 wrote:Thanks everyone,  I keep watching my tracking number updates, excited to get started.

I already have a good soldering setup (Weller digital variable with a Hakko Fume extractor) so all good there,  

How critical is the wire routing?  The reason I ask is that i was planning to follow the instructions but I always like to see how I can make things neater and cleaner (When I was working as a car audio installer, I would take hours to route each cable as neat as possible so it was aesthetically good looking as well as functional)   Now that I read some other posts I hear about Noise that was fixed by rerouting cables....

Guess I'll just follow the directions to the letter

Good idea. If you end up having a noise problem and need Bob's help... best to have followed his instructions.

Some random thoughts based on my experiences with Dynaco/VTA products:

-When painting transformer laminations, less is more
-Cutting your transformer leads short will result in some stranger cursing you 60 years from now
-One look underneath is all it takes to know who used a too-cool, dirty, or unfamiliar soldering iron
-Flux twice, solder once. I once rewired an entire Mark 6 using just an inch of 0.032" solder and 1/2 a bottle of liquid flux

...j

As mentioned, the instructions that come with the kit are excellent. I'd add one thing. DO follow them step by step, and highlight the "solder later" connections. Check off each step as you complete it, and double check all your work prior to first fire. I went through and slashed each check mark in that phase to make sure I caught everything. Last step there is a close eyeball inspection of all the connections, paying particular attention to those "solder later" connections I mentioned earlier.

DO follow the instructions for first fire, and DO use a VOM to verify all your voltages are correct before buttoning things up.

Oh. And most important ... DO have fun with it! I have an ST120, and it's the best sounding amp I've ever heard here.

PS ... I like to put a slight twist on all the tube tangs to tighten them up in the sockets so they don't drift or go out of alignment when inserting tubes. Make sure you do that straight up and down and avoid rocking the pins, and make sure the pins are clean as well. Even a brand new tube can have some oxidation on the pins that can degrade the connection. I'd also tension the sockets as well, if for nothing else, for practice, as that should be a regular part of your maintenance any time you change tubes.

** Don't forget to do the "yellow sheet mod" on the rectifier socket. That should be normal practice for any of these amps.

https://dynacotubeaudio.forumotion.com/t1006-tube-rectifier-diode-mod

Welcome to the club...  You picked a great amp and my 5 yr. old ST120 is used daily for many hours at at time.  It is very quiet, reliable, and sounds impressive.

Some good advice would be to thoroughly go over the build instructions and parts before committing to a soldering iron or screwdriver.  I spent 2x the amount of time planning than actually building the amp. Paid off with a tidy build and easy to work on once the memory of building has faded.

Yes, the "yellow sheet" diode mod is a must. I would also recommend the HV relay delay board. I love this feature and allows me to go solid state on power supply rectification.

If you have any questions this eager bunch is willing to help make your kit building experience rewarding.

Thanks everyone,
So just be careful and use the Yellow sheet mod got it (Just checked my parts pile and I have 1n4007s lying around )

I'd also consider adding a CL90 thermistor to the main power line (center tap on the fuse). That will mitigate "inrush" current on start up.



(Or a CL80, which has a higher amp rating, but my CL90's been working fine. I've put those in ham amps that are rated at 10 amps with nary a problem. I like the CL90 because it has a higher heat dissipation factor. Which is worth mention, as them suckers get HOT, so make sure you allow max clearance around one. In case anyone's wondering, I did reroute the blue wire to get it away from the thermistor before buttoning things up.)

I'd also HIGHLY recommend adding one of these to your kit ...



Ignore the GFCI feature ... it's the "non-latching" that's of interest here. Any little power blip can kill a tube amp if it's not allowed to discharge properly. This little gem requires a manual reset when power is interrupted, so just leave the amp off until the weather (or whatever) settles down. Great protection for less than $20.

TRC 90033 Shockshield White Portable GFCI Plug with Surge Protection

Welcome to Tommy's Holiday Camp!
We're here to answer any question, and if we don't have the right answer, we'll make sumpin' up that sounds really cool and erudite. The advice proferred so far has been excellent, and Bob L. never sleeps and quick to get back to you. Just take your time and make this building time as much fun as listening to it is going to be.
One thing I would add: if you're used to working w/ teensy stuff, remember that those ground lugs and others suck up a lot of heat. Consider a flat-bladed hi-watt gun for those.

deepee99 wrote:Welcome to Tommy's Holiday Camp!

Thanks Uncle Ernie


To answer the myriad, I was wondering about the Thermistor as I have had several people on HAM forums mention using one with Tube gear.., I have one that was earmarked for my HW-101 when I finally get around to restoring that, but it may wind up in this ...

At this point, I think I will build it as written, get it working then once it 's good to go make my "mods"

So current Mods list is:

1) Yellow Sheet Mod
2) Thermistor
3) Relocate input jacks to rear (for a cleaner look )

I'll look at one of those power interrupter units too, we don't have many power outages here, but better safe then sorry

'Nuther question

I got my amp with the variable input attenuation unit as I will be driving this from a Pro-Ject Tube Box DS, Is that good enough or should I really get a decent pre-amp? I was eyeing the kits on Bob's site... (Like the idea of building )


Thanks in advance as always!!!

Another ham in our midst, Dave, did you get that?!

Welcome McGyver 74. You're gonna enjoy that amp. As others have said, the instructions are excellent, support from corporate headquarters is beyond reproach, and the forum is sure to remain a friendly corner of the web to hang out before, during, and long after the amp is finished.

de Brenton
VE6IE

Tube Nube wrote:Another ham in our midst, Dave, did you get that?!

Welcome McGyver 74. You're gonna enjoy that amp. As others have said, the instructions are excellent, support from corporate headquarters is beyond reproach, and the forum is sure to remain a friendly corner of the web to hang out before, during, and long after the amp is finished.

de Brenton
VE6IE

I did indeed, Brenton. And a ham in the literal licensed sense? Just about everyone on this board is a ham, just a few of 'em don't have call signs.
Back when I was active in hamming, I went the solid-state pwr supply route in my S-line rack, causing gigantic explosions of the 6146As. My first true lesson in proper "biasing." Same applies to our tube audio gear, if switching from tube to s/s rectification. Fortunately, having learned this, I turned the bias pots all the way down before going from tube to the solid-state Webers. Lots of opinions here on whether tube or sand rectifiers sound/behave better. The "yellow sheet" mod makes a lot of that moot. McGyver, you may or may not hear a difference but try a swap and see or which if one sounds better than the other to *you.* There are three ways to go with rectification: real tube, s/s/ semi-tube Weber, or just some big honkin' diodes (there's another thread on this subject).
You hadn't mentioned it, but installing one of Bob's time-delay relays on the B+ is another must, right up with the manual-reset GFCI. Gives the filaments a couple dozen seconds to warm the tube before the serious juice gets there.
73 de
KB7-GTO (city-bound and inactive)
dave

Thanks guys,

Yeah I am a Ham, I'm only tech class but I am licensed. Due to where I live I haven't been too fast to get the General since I am severely antenna constrained. My buddy just bought a house and may be willing to let me put an antenna up there so I can run my HF rig remotely. I bought the Hotwater101 to restore it, I fired it up and was able to receive so it worked, but I didn't get a chance to really listen much before the power supply self destructed (Caps).


Anyway, I just got the kit yesterday, I want to look into having the Transformer ENd bells powdercoated to make them look real nice..... Anybody see any issues with that?

Again TIA!!!

Marc
KD2JGK

mcgyver74 wrote:Thanks guys,

Yeah I am a Ham,  I'm only tech class but I am licensed.  Due to where I live I haven't been too fast to get the General since I am severely antenna constrained.  My buddy just bought a house and may be willing to let me put an antenna up there so I can run my HF rig remotely.  I bought the Hotwater101 to restore it,  I fired it up and was able to receive so it worked, but I didn't get a chance to really listen much before the power supply self destructed (Caps).


Anyway, I just got the kit yesterday,  I want to look into having the Transformer ENd bells powdercoated to make them look real nice.....  Anybody see any issues with that?

Again TIA!!!

Marc
KD2JGK

Go for it, bearing in mind that the darker and less glossy the colour, the better the heat dissipation is going to be. There's another thread on this topic and somebody, perhaps either Bob L or Skizo, actually put up a colour chart in that context. Audio Bill has probably more experience in tricking out the iron's aesthetics than anyone. Might PM and ask him for his advice.
CQ, CQ CQ transistor junkies. Ooops, wrong band.
-d-

Cool thanks, I'm going to check out that thread