| nerd of nerds |
Hello!
I have recently become very curious about tube amplifiers. You see, one of my friends has a synthesizer that has actual tubes in it as an effect. I really liked the character it gave to the sound and i'd like to have this character/warmth in my main speakers (3" full rangers).
But after much searching i am daunted by the task of constructing one of these as i have never in my life worked with tubes. I have constructed a P2P gainclone so this will ideally be a walk in the park...
But I have yet to find a simple/low cost schematic. So, i figured that i would turn to you guys for advice.
Keep in mind that i've never worked with tubes or transformers (much) so i'd like this to be a simple low component design.
NO KITS!
Thanks! |
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| jaymanaa |
| I,m in the same boat. Try boozehound labratorys for a good tube hi-fi primer (it helped me alot). Angela Inst. sight has some schematics with parts lists. From what I've been able to dicifer single ended amps are simplest to build. The only real advice I can give is don't get in a hurry. The more I dig, the more I realize there is a lot of thought and compromise involved in choosing a circuit. I think I would have been disappointed if I had built the first thing that looked great. Your in a good place, there are some really nice people here that have been very helpful and patient with me. Good luck and keep me posted on any good stuff you find along the way jaysriviera@yahoo.com :scratch: |
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| tubelab.com |
| Before you can figure out which amp to build, you need to figure out how much power you need (or want). |
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| alexmoose |
I am kindof in the same boat, I am just to **** indecisive on what I want to build/refurbish, a very simple SE design I found from Mr. Kenji Mizushima. Despite his poor english, it looks like this amplifier is pretty cool and dilivers 4 watts of SE power!
http://members.at.infoseek.co.jp/lagarto/el84se_diy.htm |
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| jaymanaa |
| That is the question of the week for me. I really enjoyed the lundahl page you suggested tubelab. It has me wandering if 8 watts will be enough. I wish I had some way of measuring power output I'm using now on my old faithful dyna. I mean not every amp I own has to be able to irratate the neighbors but it seems to me that you need a certain amount of current to get even Heresy's making good bass. Just more thoughts on the single ended el34 project. Thanks as allways for the help, Jay:headbash: |
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| leadbelly |
| quote: | Originally posted by nerd of nerds
I really liked the character it gave to the sound and i'd like to have this character/warmth in my main speakers (3" full rangers).
I have constructed a P2P gainclone so this will ideally be a walk in the park...
But I have yet to find a simple/low cost schematic. So, i figured that i would turn to you guys for advice. |
A few comments:
(1) building a P2P gainclone is hardly a strong enough background that will make scratchbuilding a tube amp "a walk in the park"; be prepared for a challenge, but if you are up to it, also quite a rewarding one
(2) I doubt you will find a "simple/low cost schematic" that will drive a 3" fullranger, which I suppose is about 87-90 dB/1W/1m, to loud levels. I suggest you lower your expectations and just aim to build an amp that will teach you how to put together a tube amp, period. For this goal, you can search for some threads on making spud amps using the 50EH5 or similar tubes pulled out of old consoles, or using new 6C45P tubes. If you want to aim higher you can probably buy new Edcor PP transformers and new Russian 6BM8 equivalents on eBay to build something with a bit more power. |
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| lndm |
| quote: | Originally posted by jaymanaa
I wish I had some way of measuring power output I'm using now on my old faithful dyna.
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Can you just play a tone (maybe 200Hz?) until you hear clipping and measure RMS voltage with dmm? More accurate with a CRO of course. |
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| nerd of nerds |
| quote: | Originally posted by leadbelly
A few comments:
(1) building a P2P gainclone is hardly a strong enough background that will make scratchbuilding a tube amp "a walk in the park"; be prepared for a challenge, but if you are up to it, also quite a rewarding one
(2) I doubt you will find a "simple/low cost schematic" that will drive a 3" fullranger, which I suppose is about 87-90 dB/1W/1m, to loud levels. I suggest you lower your expectations and just aim to build an amp that will teach you how to put together a tube amp, period. For this goal, you can search for some threads on making spud amps using the 50EH5 or similar tubes pulled out of old consoles, or using new 6C45P tubes. If you want to aim higher you can probably buy new Edcor PP transformers and new Russian 6BM8 equivalents on eBay to build something with a bit more power. |
I agree with you about the gainclone thing...But that is just the most recent thing i've finished. I have done MANY other electronic projects before this.
As far as finding some old tubes from consoles...I nicked the old tubes from my big *** philco radio and thus far i have (there are still individual tubes in there) a pair of 7x7s, and a pair of 6k6gts.
I'd like to keep this as simple as possible. This will definetly be an experimentation project. Although i would like to get some good use out of the final product maybe as a pc speaker amp or something like that...
I have plenty of resistors on hand FWIW. |
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| leadbelly |
| quote: | Originally posted by nerd of nerds
I'd like to keep this as simple as possible. |
As I said, it doesn't get simpler than a spud amp. Here's one example. You can search for others, Geek posted a nice one recently.
http://digilander.libero.it/paeng/a...le_Tube_Amp.htm |
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| arnoldc |
| simple? single EL34 in ultralinear. if you have a preamp with good drive, you don't even need a driver :D |
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| nerd of nerds |
YAY!!!
I've been learning a lot about tubes this weekend :D
I think i've settled on this design. It is simple, few components, and el84s are cheap.
http://www.tubecad.com/september99/page11.html
Now, my next mission is to get 360ish volts into this thing...
I know the conventional way is to use transformers and go straight from the wall. I have no problem with this but seeing as this is more of an experimental project...
Could i use, oh, say, a 12v wall wart and use voltage multiplying circuits on it?
Thank you all for all of your help. This truely is a great forum... |
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| lndm |
Your wall wart idea is too good to be true IMO. Even an experienced ps builder that could do this well wouldn't choose to.
Also, building a voltage multiplier may require extra time and effort. |
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| Eli Duttman |
I agree with Indm. Massive voltage multiplication works when the draw is neglegible.
OTOH, a low cost 1:1 isolation trafo feeding a SS diode "full wave" voltage doubler will yield a B+ rail of about 330 V. |
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| nerd of nerds |
| quote: | Originally posted by Eli Duttman
I agree with Indm. Massive voltage multiplication works when the draw is neglegible.
OTOH, a low cost 1:1 isolation trafo feeding a SS diode "full wave" voltage doubler will yield a B+ rail of about 330 V. |
Any chance that you'd provide me with a schematic ;)
I was just throwing the idea out there of using a wall wart...i figured it probably wouldn't work, but i figured, what the heck...
Thanks for all of your help! |
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| nerd of nerds |
This provides 170 volts...
PLEASE correct me if i'm wrong...
But the output on a transformer that is 12 volts would be 12 times 1.41, which would be close to 17 volts.
Then this schematic feed the 17 volts into another transformer which in turn multiplies the voltage by 10 thus giving us our wonderful 170b+ supply.
Could i use a couple of rat shack 25.2 trafos in place of the 12 trafos? If my assumptions are correct, then that would get me a bias of about 355 volts, perefect for this project.
Am i correct? Or am i just horribly wrong? |
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| planet10 |
| quote: | Originally posted by leadbelly
making spud amps using the 50EH5 |
http://www.t-linespeakers.org/tubes/SEP_50EH5.html (links to some other 50EH5 amps there too).
The 6C45pi amp is likely better, but you can build one of these up for the cost of a pair of 6C45s if you are good at scounging. It is also low voltage as far as tubes go. Makes a great little amp if your needs are modest, and if you get decent OPTs would make a good tweeter amp strapped in triode (for an efficient tweeter). I can likely help you with iron if you need.
dave |
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| nerd of nerds |
| quote: | Originally posted by planet10
http://www.t-linespeakers.org/tubes/SEP_50EH5.html (links to some other 50EH5 amps there too).
The 6C45pi amp is likely better, but you can build one of these up for the cost of a pair of 6C45s if you are good at scounging. It is also low voltage as far as tubes go. Makes a great little amp if your needs are modest, and if you get decent OPTs would make a good tweeter amp strapped in triode (for an efficient tweeter). I can hekp you with iron if you need.
dave |
How well do you think that would power a couple of hi-vi b3n speakers (no filters...)?
I like that design but the one that i linked to using the el84 seems as though it would be simpler to build. On the next page it has another schematic to use 5 el84s in series, which i really like the idea of. I can build an external power supply for it so if i feel like upgrading in the future, i don't have to muck around with making a new PS.
I have learned a lot about tubes in the past few days :-D
And as i said, i have some 6K6GT tubes on hand... |
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| planet10 |
| quote: | Originally posted by nerd of nerds
I like that design but the one that i linked to using the el84 seems as though it would be simpler to build. |
The EL84 would be a better amp (and 3 x the power )-- no question, but with the driver stage required is much more complex (ie ignoring the cathode feedback, a 50EH5 amp is the same topology as the EL84 if you tossed the input tube and connected the input to the EL84 grid leak (ie ~ half the parts).
dave |
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| nerd of nerds |
| quote: | Originally posted by planet10
The EL84 would be a better amp (and 3 x the power )-- no question, but with the driver stage required is much more complex (ie ignoring the cathode feedback, a 50EH5 amp is the same topology as the EL84 if you tossed the input tube and connected the input to the EL84 grid leak (ie ~ half the parts).
dave |
****.
I understood about half of what you said...
What exactly do i need to get the schematic i linked to to work with, say, my computer?
If you think your amp could comfortably power a couple of zaph's hi vi full range speakers in a somewhat small room then i will go ahead and build yours. |
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| Eli Duttman |
| quote: | Originally posted by nerd of nerds
Any chance that you'd provide me with a schematic ;)
I was just throwing the idea out there of using a wall wart...i figured it probably wouldn't work, but i figured, what the heck...
Thanks for all of your help! |
Look here at the B+ supply used in "El Cheapo". That supply is good for 200 mA. of DC. For a lesser draw, a smaller 1:1 isolation trafo is in order. The 1:1 trafo should be rated for an AC RMS draw 4X the DC B+ draw. |
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| lndm |
| Thats one interesting 12ax7 circuit youve found there. It is uncommon and probably a bad one to learn from. Might I suggest you find a single el34 amp schematic that has a 12ax7 driver. |
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| Sherman |
| Do a search here for Mikael's SE KT88 amp. Very simple, only 3 tubes if you build it as stereo (4 tubes if built as monoblocks). A few resistors and caps and a volume pot. |
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| kathodyne |
hey nerd of nerds!
I built that 'strange' 12AX7 circuit.....!
I wanted to build a cheap battery operated amp, it works gives way less than a watt...
HV is derived from an astable multivibrator...
For stereo you could do about 4 hours of listening with a scooter-battery (incl. heaters)
i used an opel bobine as opt!!
it sounded quite allright but nothing fancy...an autoformer is way from ideal!!!!!
never thought i'd see that one again....!
greetz ! |
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