I had no idea of electronics when i build my first tube amp. It's not that difficult...
You need a transformer that gives you 280 Volts or so. You could look in old tube radios or you could use 2 back to back. It's quite simple:
230/12 ----------12/230 if you connect the 12v secondary of the first transformer to the 12 volts tap of the second transformer this second trafo will give you 230 V in its primary. You then rectify that AC to DC with diodes(full bridge) and you have 285volts. Then you filter this voltage RCRC and you'll have 260V for your B+.
Any doubt?
Just asK.
Depending of the current you may need to use big ones... 2 amps 230/12 transformers should be enough.
You need a transformer that gives you 280 Volts or so. You could look in old tube radios or you could use 2 back to back. It's quite simple:
230/12 ----------12/230 if you connect the 12v secondary of the first transformer to the 12 volts tap of the second transformer this second trafo will give you 230 V in its primary. You then rectify that AC to DC with diodes(full bridge) and you have 285volts. Then you filter this voltage RCRC and you'll have 260V for your B+.
Any doubt?
Just asK.
Depending of the current you may need to use big ones... 2 amps 230/12 transformers should be enough.
hi mark, there is a sticky about tube building safety and i suggest you read it.
i have wired my 12B4 pre last night, i should be able to post some info tomorrow.
before you buy your power transformer, we should pick an appropriate B+ for better sonics from the 12B4. The schema in the diyparadise is 260V and mark's is 300V. let's see about that.
have you figured out the chassis yet? for simplicity, you may want to use a hammond 1440 seriess, IIRC. then maybe in the U might have a drill press and stepped drills for you to bore holes on it.
you can start buying the things like 9-pin tube sockets x 2, RCA connectors 4 pairs (3 input, 1 output as you wished), ALPS volume pot, a decent selector like Grayhill, two nice looking knobs, some shielded wire (i use locally-available-japan-made shielded wires).
i have wired my 12B4 pre last night, i should be able to post some info tomorrow.
before you buy your power transformer, we should pick an appropriate B+ for better sonics from the 12B4. The schema in the diyparadise is 260V and mark's is 300V. let's see about that.
have you figured out the chassis yet? for simplicity, you may want to use a hammond 1440 seriess, IIRC. then maybe in the U might have a drill press and stepped drills for you to bore holes on it.
you can start buying the things like 9-pin tube sockets x 2, RCA connectors 4 pairs (3 input, 1 output as you wished), ALPS volume pot, a decent selector like Grayhill, two nice looking knobs, some shielded wire (i use locally-available-japan-made shielded wires).
don't rush;Commited said:
nobody here was born with knowledge and praxis
besides-don't give up tube preamp just because they have high and low voltage supply-you have also 230 V on input of silly +- 12 V supplied preamp with OP chips.....
just lurk here,find some books about electronics (download bookmarks.rar from my site,there you'll find some good links in "books" folder) and learn...
gradually you'll know more and in one moment you'll be ready to make your own gadgets.
when I made first steps in tube audio (eons ago) all I knew was difference between primary and secondary in xformer
now- at least 20 electroshocks later-I know better only -how much I don't know
Commited said:
The above two are the only 2 types of transformer available in Ireland
You may indeed be commited, but need some work in the resourceful department. Thirty seconds found me a supplier in Ireland that carries several thousand different transformers. No doubt there are more...
http://ie.farnell.com/jsp/endecaSea...&Ntt=transformer&Ntk=gensearch&comSearch=true
SY said:
Thanks SY.
I was told that farnell didnt deliver to Ireland so I wrote them off.
http://ie.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=4443627&N=401
http://ie.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=4443664&N=401
Would either of them be better than putting 2 back to back?
I have found this small retailer in the UK:
Bluebell.
They do Hammond transformers etc as well as loads of other stuff:
Heaters: http://www.bluebellaudio.com/filament.htm
Transformers: http://www.bluebellaudio.com/transmain-mains.htm
Chokes: http://www.bluebellaudio.com/new home.htm
There must be stuff on there that would be suitable.
Reading another source, it mentioned that the 12B4 circuit I displayed above used the same power supply as that for a Simple 5687..
"Power supply is as simple (and cheap) as it gets. A 110:220VAC isolation xfmr - to a bridge rectifier (1N4007's) - to a 200u/330v photo-flasher - to a 75ohm WW Resistor - to another 200u/330v photo cap. That's it!
B+ is about 265VDC and only drops to 257VDC or so at max sine-driven output power.
Ripple at B+ is a little less than 200mVpp. This results in less than 10mVpp of output noise/hum thanks to push-pull output topology and differential driver."
I'm thinking with a 230:230 isolation transformer instead, it should be ok?
Is this any good?
http://www.the-planet.org/6GV8.html
Opinions on attached PSU?
Bluebell.
They do Hammond transformers etc as well as loads of other stuff:
Heaters: http://www.bluebellaudio.com/filament.htm
Transformers: http://www.bluebellaudio.com/transmain-mains.htm
Chokes: http://www.bluebellaudio.com/new home.htm
There must be stuff on there that would be suitable.
Reading another source, it mentioned that the 12B4 circuit I displayed above used the same power supply as that for a Simple 5687..
"Power supply is as simple (and cheap) as it gets. A 110:220VAC isolation xfmr - to a bridge rectifier (1N4007's) - to a 200u/330v photo-flasher - to a 75ohm WW Resistor - to another 200u/330v photo cap. That's it!
B+ is about 265VDC and only drops to 257VDC or so at max sine-driven output power.
Ripple at B+ is a little less than 200mVpp. This results in less than 10mVpp of output noise/hum thanks to push-pull output topology and differential driver."
I'm thinking with a 230:230 isolation transformer instead, it should be ok?
Is this any good?
http://www.the-planet.org/6GV8.html
Opinions on attached PSU?
Attachments
OK, so I looked up your profile, and you lack the experience of us old farts. Don't worry about that. You have less money to throw around than we do, so valve regulators might be cheaper than chokes, and silicon regulators are definitely cheaper. At your age, I couldn't even dream of regulated supplies, so don't worry too much about them - get the audio department right first...
I just sold all my old Arcam/B&W stuff for quite a bit, so I'm not doing too badly cash wiseEC8010 said:
My new transport/DAC & power amps should come to about £300, so I have a couple of hundred to play around with to get it right!
You're right with the experience - I'd never looked at valves before last week, so I suppose I'm rushing a bit. I think chokes recommendation of reading a few books is a good one.
Any tips for good places to get parts in the UK?
If I could get someone to build the power supply for me, I'd be laughing - the rest of it isnt hard at all. The chassis etc isnt an issue for me - thats probably the easiest part.
I hate to say it, but you'd be amazed at how much valve stuff costs when you don't know precisely what you are doing. I'm afraid there aren't any "bargain" places in the UK any more. In the 80s, I bought transformers (for valve kit) at 20p per pound (weight). I look back in amazement at those prices.
I built the simple 5687 preamp from the same site. Sounds great, nice big punchy sound. I'am not using it at the moment because I have a version of the Super linear design by Joe Rasmussen which sounds more neutral.
Still if this preamp is anything like as good as the 5687, then its well worth building.
Simple CRCRC filtering should do fine. Chokes would be better but there not easy to come by. I know that back to back transformers aren't the best solution, but it works very well with anything up to 50mA or so. I am using it in my preamp and in a headphone amp. If it gets the thing built then I highly recommend it. The great side benefit of using back to back is that if the secondary voltage is correct then you can use one of the first transformers secondaries for the heaters. Say 12V running the heaters in series slightly lean (good for tube life), or with a 15V secondary with a little bit of ballast resistance to bring the voltage in line. Also if you make the second transformer a lower voltage then you can get a useful voltage increase which allows more headroom for filtering.
ie 230:15V > 12:230 will give you a final voltage of 287.5V (ignoring loses). Rectified you have 400V.
Two EI's from farnell wouldn't break the bank. Otherwise preamp transformers on Ebay are cheap.
Shoog
Still if this preamp is anything like as good as the 5687, then its well worth building.
Simple CRCRC filtering should do fine. Chokes would be better but there not easy to come by. I know that back to back transformers aren't the best solution, but it works very well with anything up to 50mA or so. I am using it in my preamp and in a headphone amp. If it gets the thing built then I highly recommend it. The great side benefit of using back to back is that if the secondary voltage is correct then you can use one of the first transformers secondaries for the heaters. Say 12V running the heaters in series slightly lean (good for tube life), or with a 15V secondary with a little bit of ballast resistance to bring the voltage in line. Also if you make the second transformer a lower voltage then you can get a useful voltage increase which allows more headroom for filtering.
ie 230:15V > 12:230 will give you a final voltage of 287.5V (ignoring loses). Rectified you have 400V.
Two EI's from farnell wouldn't break the bank. Otherwise preamp transformers on Ebay are cheap.
Shoog
hi mark, were your choke values selected based on availability? i think you should for something like 5H 60mA units.
secondly, if I remember right, the 20mA is for a single channel, so you need to put in 40mA in your current load for a stereo.
lastly, if you find it difficult to find appropriate chokes, i'd suggest a 10uF-1K-100uF-1K-100uF-1K-100uF. i've used this successfully in one of my preamp and has no visible ripple on the scope (unless my scope is broken)
secondly, if I remember right, the 20mA is for a single channel, so you need to put in 40mA in your current load for a stereo.
lastly, if you find it difficult to find appropriate chokes, i'd suggest a 10uF-1K-100uF-1K-100uF-1K-100uF. i've used this successfully in one of my preamp and has no visible ripple on the scope (unless my scope is broken
)Thanks for the input arnold.arnoldc said:hi mark, were your choke values selected based on availability? i think you should for something like 5H 60mA units.
secondly, if I remember right, the 20mA is for a single channel, so you need to put in 40mA in your current load for a stereo.
lastly, if you find it difficult to find appropriate chokes, i'd suggest a 10uF-1K-100uF-1K-100uF-1K-100uF. i've used this successfully in one of my preamp and has no visible ripple on the scope (unless my scope is broken
I picked the chokes due to availability, yeah. I could get some stuff from DIYparadise as I'm ordering some stuff soon but it's quite expensive with postage.
I'm going to have to rethink my design seeing as it's now a 40mA load..
The 10uF-1K-100uF-1K-100uF-1K-100uF didnt seem to work according to the software
Am I on the right track though?
mark, it is important for you to feed the estimated DCR of your power transformer into PSUD.
also, if you use 260V for my CRCRCRC, you'll get the error because the secondary is too low for the load.
if you're really stuck with 260V, you may want to use SS rectification instead (FR107 should good).
also, if you use 260V for my CRCRCRC, you'll get the error because the secondary is too low for the load.
if you're really stuck with 260V, you may want to use SS rectification instead (FR107 should good).
Hi there,
I am located in Boyle Co. Roscommon, I don't get up to Dub much.
I would go with the simple CRCRC approach, its cheap and performs very well. Once built its quite easy to adjust the voltage of the output by increasing or decreasing one of the resistors.Consider the model as a guide only. Absolute voltages in tube circuits are not that critical as they will work over quite a range of +B.
Keep things as simple as possable in your first build. The design is the least of your worries really - when you come to getting rid of hum, that the real fun bit. If you have gone for a complex circuit with lots of sophisticated features (regulation, CCS, Etc), it makes the debug process all the more complex as it gives you more things to trace the faults in. If you lay it all out correctly it is relatively easy to intoduce sophistication in incremental stages, ie a resistor can be replaced with a CCS board. Don't get to hung up on the case initially as once your've built one preamp you will tweak it to death and then build a better one. Good looks tend to disappear in this process.
You can either spend a lot of time and money on making a perfect version of a circuit you have never heard before - or you can spend a tiny amount of money using salvaged parts, back to back transformers etc, prove the design, and then know what your doing when spending the money on the final "perfect" build. The former approach tends to induce audiophile madness and huge amounts of stress (especially when your expensive components go up in smoke when you make an inevitable mistake), the latter makes for fun learning and gets a bit of experience under your belt.
Good luck.
Shoog
I am located in Boyle Co. Roscommon, I don't get up to Dub much.
I would go with the simple CRCRC approach, its cheap and performs very well. Once built its quite easy to adjust the voltage of the output by increasing or decreasing one of the resistors.Consider the model as a guide only. Absolute voltages in tube circuits are not that critical as they will work over quite a range of +B.
Keep things as simple as possable in your first build. The design is the least of your worries really - when you come to getting rid of hum, that the real fun bit. If you have gone for a complex circuit with lots of sophisticated features (regulation, CCS, Etc), it makes the debug process all the more complex as it gives you more things to trace the faults in. If you lay it all out correctly it is relatively easy to intoduce sophistication in incremental stages, ie a resistor can be replaced with a CCS board. Don't get to hung up on the case initially as once your've built one preamp you will tweak it to death and then build a better one. Good looks tend to disappear in this process.
You can either spend a lot of time and money on making a perfect version of a circuit you have never heard before - or you can spend a tiny amount of money using salvaged parts, back to back transformers etc, prove the design, and then know what your doing when spending the money on the final "perfect" build. The former approach tends to induce audiophile madness and huge amounts of stress (especially when your expensive components go up in smoke when you make an inevitable mistake), the latter makes for fun learning and gets a bit of experience under your belt.
Good luck.
Shoog
Commited said:
Thanks for the input arnold.
I picked the chokes due to availability, yeah. I could get some stuff from DIYparadise as I'm ordering some stuff soon but it's quite expensive with postage.
I'm going to have to rethink my design seeing as it's now a 40mA load..
The 10uF-1K-100uF-1K-100uF-1K-100uF didnt seem to work according to the software
Am I on the right track though?
Hi,
You may want to check out this thread, there's a lot of useful information in here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=28957&perpage=10&pagenumber=1
The thread is mostly about a phono stage suggested by Kuei Yang Wang that requires 250V dc. With a bit of modification (transformer voltage / dropping a RC filter / changing R values a little) you should be able to get the 260V @ 40mA that you require, without having to use a choke. The schematic for the PSU is in post #41. It's a multiple RC filter design.
If you're willing to try something a little different for your preamp, KYW posted an interesting parallel 6sn7 linestage schematic, found here:
http://www.diyaudio.com/forums/showthread.php?postid=353015#post353015
You can run it with essentially the same psu.
Have fun and play safe!
Griz
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