The No.1 Website for Pro Audio
 Search This Thread  Search This Forum  Search Reviews  Search Gear Database  Search Synths for sale  Search Gearslutz Go Advanced
Cheap tube preamp, worth it? Consoles
Old 11th January 2014
  #1
Gear Maniac
 
Raleigh's Avatar
 

Thread Starter
Cheap tube preamp, worth it?

I was looking at different tube amp kits on ebay. There are a bunch of different, extremely cheap DIY tube preamps shipped from China. Like this one for under $20.

Tube 6N3 Buffer Audio Preamplifier Kit DIY Pre Amp | eBay

Would this help out the sound of my dynamic mics, and warm up any other signal sent through it? Or is it crappy and not even worth buying?
Old 11th January 2014
  #2
If you wanted to learn electronics, yes. that kit would be fun. you might even be able to mod it later.

if your after good quality audio only, this may be the ladder approach or a bandaid solution.

the ladder approach has its pros and cons like everything else does.

is it starved plate?
Old 11th January 2014
  #3
Gear Maniac
 
Raleigh's Avatar
 

Thread Starter
I'm not really sure exactly? Yeah this project looks fairly easy and straight forward. I've built fuzz boxes and a few other things before although I don't really know what a plate starved pre amp is? I wonder if swapping the tube out for a better one would sweeten the sound up?
Old 11th January 2014
  #4
Lives for gear
 
grumphh's Avatar
 

A tube is just another electrical component (although rather outdated) and may or may not have a positive influence on your sound.
It all depends on the circuitry around it.

In other words, forget about the notion that just putting a tube in your signal path will automatically make the sound "warmer" or "better".

Tubes are not magic bullets.
Old 11th January 2014
  #5
The circuits really what your paying for here and it doesn't look like there showing it off.

starved plate is kinda like getting half a tube preamp. it's hard to explain and i don't understand enough about it to really go into detail, but it's not using all the tubes potential.

doesn't neccesarily make it bad. but it is different.

bigger thing is if you like it. try it out. it's 6 bucks and a few hours time. if it sucks sell it back on evilbay. you never know what is going to be good to your ears until you try it.
Old 11th January 2014
  #6
If it ends up sucking for preamps...turn it into a pedal!
Old 11th January 2014
  #7
Lives for gear
 
wwjd's Avatar
hmmmm.... can't answer on the fun of a KIT build if that is an important part of your decision.... but I bought the cheapest ART tube pre I could find, just to boost mic signal, and was pleasantly surprised that is DID improve the sound for me... or rather, ALTER/color the sound in an interesting way. I have put my AKG P200 and 414 through it... just another coloring option. So, to me, it was worth it.
Old 12th January 2014
  #8
If its starved plate it wont really add much other than distortion...which may be useful as an effect. Like others say it might be more interesting to build it.
Old 12th January 2014
  #9
be careful with tube designs. start with building some low voltage, low amperage solid state designs. safer!
the above chinese thingy looks like a fun project but don't expect too much of it. it's a simple buffer amp, not a powerhouse.... how much is it? less than 20 bucks? you'll need a housing though... and a power transformer.

here's antoher one
Buffer 6N3 Tube Amplifier Preamp Amp Pre Amplifier Matisse Kit with Transformer | eBay

here's a PCB that would I expect more from
PMillett Tube Mic Preamp

most of the "warmness" of tube circuits comes from audio transformers.... If I were you, I'd buy a little cheap pedal kit or synth building block, and not start with a tube kit. I'd expect more "warmth" from a nice 500 series eq or such...
Old 12th January 2014
  #10
Gear Maniac
 

I definitely don't have the technical knowledge to comment on this design and have obviously never tried it, but I bet with some DIY skills this could be made into a cool obnoxious distortion effects box. Add some character, like others have said here.

I seriously doubt it will have anything in the way of warming effects on sources though. In my experience the lower end tube boxes have not had anything like the nice magic we all want from tube boxes. They can still make sweet sounds though, obviously. Like that cheap ART tube pre.

I've just re said what was already said here. Haha. But I've also been studying electrical engineering and just recently getting into DIY audio and messing around with this circuit seems fun enough that I might buy one myself.
Old 12th January 2014
  #11
:-) then by all means... go for it.

I added a link - check out the Drip kits... pure beauty!
Old 12th January 2014
  #12
m.o
Lives for gear
 
m.o's Avatar
 

Be careful with tube designs, at least "real" tube circuits (as opposed to starved plate, I don't quite know how these work) uses high DC voltages in the circuit (200-300+ Volts DC) that can easily kill you for real, and you'll have to read up on HV safety a bit (discharging caps properly etc).
A non-tube design OTOH is much safer to muck around with (voltages usually 24Volts or less) worst case you destroy some component or blow a fuse.
Old 25th April 2015
  #13
Gear interested
 

6n3 Amp voltage

I know the plate voltage is 150 for this tube, which allows alternate (step up) voltage supplies. Tubes that are cheap and a cheap non-transformer power supply sounds perfect if it can be a good sounding alternative. I am interested in using it as a single channel clean boost and am looking for a schematic that would use both sides of the tube to amplify a single signal.

I have not seen anything out there that will do it. Has anyone here?
Old 25th April 2015
  #14
Lives for gear
 
robot gigante's Avatar
Suggest to repost the question in the Geekslutz forum on this site. Odds are better you might get a good answer to this type of question there. Good luck!
Old 25th April 2015
  #15
Gear Nut
 

I built a preamp with that pmillet board, though I modded mine with a nice output transformer, which then necessitated a few minor circuit tweaks. All in all though it sounds incredibly warm and rich. It has nice smooth top end but it can't really do "bright".

That said I have also experienced small starved plate pres, specifically ARTs offerings. They have a definite sonic texture to them, but it isn't the most useful. If you are looking for a fun weekend project the 20 dollar kit will be exactly that. If you are looking to have a lifelong worthwhile piece of gear you will probably wind up being disappointed.
Old 11th May 2015
  #16
Gear interested
 

Quote:
Originally Posted by tomsamps View Post
I know the plate voltage is 150 for this tube, which allows alternate (step up) voltage supplies. Tubes that are cheap and a cheap non-transformer power supply sounds perfect if it can be a good sounding alternative. I am interested in using it as a single channel clean boost and am looking for a schematic that would use both sides of the tube to amplify a single signal.

I have not seen anything out there that will do it. Has anyone here?
Anything other than the starved plate are giong to use high voltages, so be careful.

There really is no such thing as a "non-transformer" power supply, there is going to be somekind of transformer, whether "wall wart" or a big heavy 700v Stancor. If you are looking to use a wall wart, then you're looking at the earlier "starved plate" design, which is more of an effect, or you can use a voltage tripler The 'RoyerMod' microhpone mod uses wallwarts and a voltage tripler to get 100vdc for the tube.

or two transformers with one wired backwards:

The Real McTube Article: Construction

I don't exactly understand the physics of starved plate, but it is working the tube in such a way to exaggerate tube distortion, (non-linear) to "warm" up a signal. It's an effect. It's not a bad effect, but an effect, and you're dealing with safer voltages.

I have the second 6N3 one listed up there, the higher voltage 6N3 one. It has some design flaws (way too low input impedance) but I hacked it a bit, and it isn't bad. Somewhat lower gain, but all I did was chip off the 10k surface mount resistor and attached a 1Meg resistor across a phone jack. I have this setup. The gain is pretty low, but it works nicely running a guitar in to a line in, and the volume knob wide open. You can get a suitabale HV transformer from Allied for about $20, also Edcor probably has one with both the 150v and 6.3v you need.

See this thread:

"6N3 HiFi Buffer Amp" -- what does it really do? Schematic corrected again

and this one for some mods

6N3 'HiFi Buffer Preamp' = inexpensive tube preamp - Page 3 - Home Recording forums

Depending on what you mean by "boost" the 6N3 will do the trick. I haven't really checked to see what kind of freq response it gets though. The McTube can give you some gritty distortion (I've built something like that.) You can get a PCB for that one from tonepad
Old 12th May 2015
  #17
Lives for gear
Warmth is distortion. It is up to you how much you want or need. I think cheap tube pres are more trouble than they are worth, if improving or warming up your sound is what you are after. I find subtle change is good.
Old 12th May 2015
  #18
Gear Addict
 

Quote:
Originally Posted by Reptil View Post
most of the "warmness" of tube circuits comes from audio transformers....
this
just buy some vintage transformers and wire them for 1/4" IO
less space less hassle more sound
Topic:
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Forum Jump