i'm an EE student with a little knowledge of circuts, mostly picked up as i go. i think audio is neat, but don't really call myself an audiophile. i hate hiss.
in any case, i'm building an amp for some spekaers for my computer. i'm wondering if a tube amp or tube preamplifer is a feasible thing to try. i already have parts for a gainclone (except for PCB).
since i know about nothing about tubes (and you can insert links that explain their useage and how they work) i am at a slight disadvantage.
in the end, i'm looking for something that will change the sound noticably, hopefully in a good way, and be cheap.
since i am a college student, i have limited funds.
so is a cheap tube preamp feasible?
in any case, i'm building an amp for some spekaers for my computer. i'm wondering if a tube amp or tube preamplifer is a feasible thing to try. i already have parts for a gainclone (except for PCB).
since i know about nothing about tubes (and you can insert links that explain their useage and how they work) i am at a slight disadvantage.
in the end, i'm looking for something that will change the sound noticably, hopefully in a good way, and be cheap.
since i am a college student, i have limited funds.
so is a cheap tube preamp feasible?
theChris said:
You won't need a preamp as the S/C should put out enough voltage to drive a poweramp. Just put a VC at the input.
The Grounded Cathode Amplifier article at Tubecad is the best. When you understand that, read the rest of the site.
If you want a tone control, simply design them ito the circuit. A good tube amp won't colour the sound appreciably, unless it's designed to like a guitar amp.
Cheap is relative. If you hunt around for second hand parts like power and output transformers, then it can be done for a modest cost. This will take some time, but there are good new parts in the Hammond iron which are quite cheap. Glass and iron are probably where the bulk of you expense will be, and that will be determined by how much power you want. If you want more than a couple of watts, then also select a less commonly used, but still common tube like the 807 to build around.
I beleive there are also some really cheap kits, but I can't find the link in my biikmarks so someone else hopefully will post.
Our resident 'honorary Scot' (short arms long pockets) Tim will have ideas and resources as he only builds amps that cost $3.
A good parts source is AES. Probably not the absolute cheapest, but good service, shipping and specials and will at least give you an idea of what some parts will cost.
A tube preamp / linestage is very easy to implement, and would only take a few hours to build. You could use a 6SN7 or 12AU7 dual triode (two devices in one glass tube) and a tube rectifier. Do a google search for a 6SN7 linestage schematic and see what you come up with. For better results you could use SRPP with one tube per channel.
A power transformer could be got from an old radio, reel-to-reel or even a couple of back-to-back 6V transformers.
Tubes are easy, look good and sound better...
A power transformer could be got from an old radio, reel-to-reel or even a couple of back-to-back 6V transformers.
Tubes are easy, look good and sound better...
I forgot to include this earlier. Bit of a long read and very informative. Not exactly a beginner work, but will give you plenty to think about if you want to play with tube amps.
http://w3.mit.edu/cheever/www/cheever_thesis.pdf
http://w3.mit.edu/cheever/www/cheever_thesis.pdf
Hi,
S/C... Source? CDP, DVD or anything else with a 2V RMS output high enough to drive an amp to full blast?
VC, volume control.
SRPP, Shunt Regulated Push-Pull.
A nice nomer for a not so well regulated PP circuit that can sound really good, offers a nice alternative where cathode followers are not wanted.
It has a lot of mutants, some more complex than others but what most seem to forget is that for the SRPP to shine you really need a very good PSU....which kind of proves that it doesn't regulate itself all that well.
Cheers,
S/C... Source? CDP, DVD or anything else with a 2V RMS output high enough to drive an amp to full blast?
VC, volume control.
SRPP, Shunt Regulated Push-Pull.
A nice nomer for a not so well regulated PP circuit that can sound really good, offers a nice alternative where cathode followers are not wanted.
It has a lot of mutants, some more complex than others but what most seem to forget is that for the SRPP to shine you really need a very good PSU....which kind of proves that it doesn't regulate itself all that well.
Cheers,
S/C = source component. VC = volume control. I think.
What's your budget? The Bottlehead Foreplay (found at www.bottlehead.com) is a pretty nice sounding tube preamp for $150. Not the best thing you can build at that price, but it's really simple to build, the support on the forum is outstanding, and it's a heck of a lot of fun. That was my intro to DIY audio, FWIW.
What's your budget? The Bottlehead Foreplay (found at www.bottlehead.com) is a pretty nice sounding tube preamp for $150. Not the best thing you can build at that price, but it's really simple to build, the support on the forum is outstanding, and it's a heck of a lot of fun. That was my intro to DIY audio, FWIW.
Sorry. S/C = sound card and VC = volume control. A soundcard will likely put out a couple of volts, easily enough for it to be connected to a power amp through a simple volume control. I think a preamp is a waste of your limited resourves.
SRPP was answered by Frank. But if you want to know more voila!
A second hand fixer upper tube amp might be an option for you too, as you have most of the expensive bits, ie the iron there already. Put ads in the local papers and ask around. Someone will likely have one in their attic/basement they'll let an engineering student have for free. A thorough rebuild will teach you as much, maybe more, than a scratch build.
SRPP was answered by Frank. But if you want to know more voila!
A second hand fixer upper tube amp might be an option for you too, as you have most of the expensive bits, ie the iron there already. Put ads in the local papers and ask around. Someone will likely have one in their attic/basement they'll let an engineering student have for free. A thorough rebuild will teach you as much, maybe more, than a scratch build.
BTW, i've been doing more research on tubes. like pentodes and tetrodes and triodes and all. and then i saw a thread about low voltage tubes and tubes for preamplifers.
in any case, what would some cheap and decent tubes for this use be? i see ecc86 pop up, what about 12au7 or 12au7a?
ADDED Q. as for the power supplies, i usually see a tube diode. is this required or could i use PN diodes of proper rating?
in any case, what would some cheap and decent tubes for this use be? i see ecc86 pop up, what about 12au7 or 12au7a?
ADDED Q. as for the power supplies, i usually see a tube diode. is this required or could i use PN diodes of proper rating?
theChris said:
Do you mean ECC88? If so that's a 6DJ8/6922 family tube and works OK at low voltages.
The 12AU7's are popular amongst certain sectors of audiophilia, but I think they suck. Try a 6CG7/6FQ7/6SN7/ECC99/7N7 instead.
Aboe suggestions are for preamp use (I don't think you need one) or were you intending using them as a driver tube in a poweramp?
no, i think he means ECC86 Brett.
ECC86 was a .. i forget the name for it..
dual triode, designed for RF amp & osc. in car-radios.
B+ was directly to the battery (6,12,24v).
Max B+ for it is 30v.
so it truely is a low voltage tube.. ive got one here somewhere. i just somehow doubt that it would sound very good.. who knows though
depends what you have in mind by LV though, i guess. some would consider 6DJ8/ecc88 and the like to be lv, and.. i guess they are. just not super lv
(by the way, the plate structure and everything looks very similar to ECC88, kind of neat..)
ECC86 was a .. i forget the name for it..
dual triode, designed for RF amp & osc. in car-radios.
B+ was directly to the battery (6,12,24v).
Max B+ for it is 30v.
so it truely is a low voltage tube.. ive got one here somewhere. i just somehow doubt that it would sound very good.. who knows though
depends what you have in mind by LV though, i guess. some would consider 6DJ8/ecc88 and the like to be lv, and.. i guess they are. just not super lv
(by the way, the plate structure and everything looks very similar to ECC88, kind of neat..)
ECC86 substitute
The ECC86 crosses to a 6GM8, you can get the at Antique Electronic Supply
http://www.tubesandmore.com/
for $4.70 ea.
The ECC86 crosses to a 6GM8, you can get the at Antique Electronic Supply
http://www.tubesandmore.com/
for $4.70 ea.
wow, thanks. really here is my goals:
1.) play with tubes and learn terms ect... some of this is done already, as i've been doing the research. next week i'll go to the college library and pick up some books on such stuff.
2.) build a simple, i guess you could call it a "tube processor" that takes a signal and gives it that some of that tube amp sound, but without the associated cost of going all out on the tubes. i am assuming this processing will not work at high levels where the power amp will be more overdriven. in anycase, almost anything that noticably changes the sound would be nice enough.
3.) impress friends with something of a centerpeice. afterall, tubes just have that ... tube look to them.
4.) not cost too much. i am in college.
so i was thinking the ecc 86/88 tubes run off low voltage would be great as i already have some low voltage transformers.
my question about using silcon or such diodes instead of tube diodes for the power supply still stands.
1.) play with tubes and learn terms ect... some of this is done already, as i've been doing the research. next week i'll go to the college library and pick up some books on such stuff.
2.) build a simple, i guess you could call it a "tube processor" that takes a signal and gives it that some of that tube amp sound, but without the associated cost of going all out on the tubes. i am assuming this processing will not work at high levels where the power amp will be more overdriven. in anycase, almost anything that noticably changes the sound would be nice enough.
3.) impress friends with something of a centerpeice. afterall, tubes just have that ... tube look to them.
4.) not cost too much. i am in college.
so i was thinking the ecc 86/88 tubes run off low voltage would be great as i already have some low voltage transformers.
my question about using silcon or such diodes instead of tube diodes for the power supply still stands.
You could scrap a crappy old tube radio (not a good one!) or tube reel-to-reel recorder for some parts. A power transformer out of one of those will be perfect for your needs. You can sometimes re-use the tube sockets too.
You can easily use silicon diodes (eg plain old In4007 or UF4007) to rectify the B+ (high voltage) but it is just as easy to use a tube rectifier (and often sounds better)
You should build a linestage/preamp, it will work fine at all signal levels and never clip under normal use. Put it inbetween your CD player and solid state power amp and have a volume control on it.
You can easily use silicon diodes (eg plain old In4007 or UF4007) to rectify the B+ (high voltage) but it is just as easy to use a tube rectifier (and often sounds better)
You should build a linestage/preamp, it will work fine at all signal levels and never clip under normal use. Put it inbetween your CD player and solid state power amp and have a volume control on it.
Hi,
6GM8.
It doesn't sound great, the ECC88/6DJ8 family of valves sound better under the same conditions.
Just don't expect anything extraordinary at such low B+.
Cheers,
Hi, fdegorove!
If you are able to view the schematics preamplifier with ECC88 or PCC88 with power supply.
Tube/valve preamp do I need for a CD-payer Technics.
thank you!
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Solid state rectification is fine with a proper PS (Power Supply) design. There are those who think tube rectification is a must, but for a beginner on a limited budget they are frills.
Another good source for transformers is Edcor. They are not stocked however and you have to order them direct with a waiting period of 6wks or so. They have a budget line of SE (single end, one tube) and PP (Push Pull two tube) transformers starting at less than $20.
Another good source for transformers is Edcor. They are not stocked however and you have to order them direct with a waiting period of 6wks or so. They have a budget line of SE (single end, one tube) and PP (Push Pull two tube) transformers starting at less than $20.
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