First Build

[milsman2]

I just ordered from Dynakit. I was kind of up in the air about it then called Dynakit to ask a really quick question and he was incredibly knowledgeable and very helpful with talking me through a number of points. It's on the way (Along with EL84's and JJ ECC832 /12DW7's)!

Any things I should know about this kit or VERY easy mods I could make right off the bat to help?

[TomMcNally]

The Dynakit amp isn't a diytube product, it's a nice clone of the
original Dynaco amp. We can probably help if you run into
anything unusual.

... tom

[mesherm]

Just a few tips.
Keep a magnifying glass handy for reading resistor color codes.
Double-check all resistor values with a DMM before installing them.
When installing tube sockets, tack solder two offset legs first and re-check socket alignment. When you have verified the socket is aligned vertically then solder the remaining legs.

I'm not sure what you mean by 'very easy mods' lol...but one mod to consider would be
http://www.tronola.com/html/efb_in_a_dynaco_st-35.html

[milsman2]

Well I know it's a kit but on diyaudio even kits are considered "diy" so I figured it was appropriate to troll here for help in case of problems with the build. Thanks for the responses either way. Easy mods for me are like for the K-502 lots of people remove the DC blocking caps and things like that but a bias circuit is definitely in the future, especially given that dynakit makes a kit for this as well.

[zippy1540]

Cancel your order and get Shannons DIYTube ST-35 kit instead(love) , you'll be much happier,individual bias for each power tube, Uses common input tubes, The 12AU7 position can also use the 12BH7 which gives you more tubes to play with for that perfect sound, Plus it's a very well documented and supported kit. Everyone on this forum will help. They did for me when i built mine, it was my first tube amp.

[milsman2]

Can you post me a link to that kit? I may not order it however, because I talked to the guy or one of the guys who runs dynakit and he seemed very knowledgeable and keen to helping people building his kit. The kit includes everything and seems really solid, despite upgrades that could be made. Upgrades and mods can always be done to anything and in that light I'll probably continue with the dynakit, but feel free to link me to Shannon's ST-35.

[Shannon Parks]

Kevin Devaney runs Dynakit and he's a top notch guy. Dynakit's quality is first class, and think you'll love your new amp - great purchase and congrats. The ST35 and ST70 forums are meant to be a repository of knowledge on those circuits in general, so welcome!

My advice is to stick to the stock build. You can always mod later, but you need a baseline to compare it, too. I think then I would suggest tube rolling - there are so many EL84s out there and you may score some vintage 12DW7s, too. And down the road, you can even do something like the EFB mod (much discussed in this forum):
http://tronola.com/html/efb_in_a_dynaco_st-35.html

Shannon

[Sal Brisindi]

If you want individual bias, Dynakitparts.com has an excellent upgrade that will allow you to adjust and fine tune the bias for each EL84/6BQ5 tube. I have used and installed it on a ST-35 and SCA-35 tube amps with excellent results.

Regards,
Sal

[milsman2]

I would order Shannon's but I kind of already had a long chat with the guy who owns Dynakit. Seems like a really solid guy, very knowledgeable and willing to help over the phone if I need it. Really like the kit and can't wait to build it! :D Also the fact that he has a bias kit that can attach to the amp is really, really convenient.

[rmyauck]

I think a actual fixed bias is the way to go with an actual separate PS transformer if you are going to do it or Dave's EFB mod which would be equally as good if you are going to spend the money and do do an adjustable bias mod.

A low cost ps could be made as shown in this ps.

http://www.diyaudio.com/forums/tubes-va ... ne-10.html

Either could be added to the different implementations of the ST-35 or SCA-35.

[milsman2]

True enough but for me step 1 is build this **** amp and let 'er rip. After that's done and I've wallowed in my new amp a few months from now a good bias kit and a pre amp are definitely in the foreseeable future.

[milsman2]

Are there any equivalents to ECC832 that have the same sort of visual effects as the one in this video?

http://www.youtube.com/watch?v=Iy7rio16ToI

[dcgillespie]

The tube you are seeing is commonly called a "magic eye" tube which is designed to give a visual indication of the applied signal, so that it can indicate signal strength, record level, or the presence of a 19kHz stereo pilot signal in FM stereo transmissions to name but a few of its applications. A commonly used 9-pin tube for this application was the EM84A, while the 6E5 was an older 6 pin eye tube.

Dave

[elbinster]

I added a magic-eye (EM84) VU meter to my G*S*G and it was pretty simple. Go to http://www.magiceyetubes.com/ and find one you like, search *bay for a pile of cheap ones, then browse schematics. As far as I know, no one makes magic eyes anymore, so you'll just have to look around.

There are some very complex circuits out there which calibrate the meter to specific dB levels (too much for such an imprecise meter) and very simple schematics that use a diode and capacitor to form a kind of sample-and-hold for the negative swing. There are a few considerations you have to take into account to prevent excess loading on part of your amp/preamp circuit, which I won't go into here, unless you want that info.

[rmyauck]

Too bad they don't last long, as they fade out fairly quickly. As noted maybe the bar type EM84 or EM87 are the ones to try as they work like a CRT so last for years.


http://www.radiomuseum.org/forum/life_s ... c_eye.html