for C11 you can connect 2 0.22/450volt film caps in parallel with C1 and C2 each . another option with C1 and C2 is to replace it with a single 200uf/500volt electrolytic if you can find it.
Tony said:
I am looking to ask them for a chassis that is 10"x14" for a stereo amp (7 tubes + resistors and caps and OPTs and Power supply and CCS). You think it is too small?
JojoD818 said:
You could fry C11 if you'll use 450V only as the voltage during cold starts can reach up to 480V. You can get away with C12 and C13 at 450V though.Safety First.
Yes C11 would see 340 X 1.414 = 480V DC thanks. I will series 2 X 0.22uf 450V DC caps end to end.
Do these caps have to be non polar?
Tony said:
parallel or series? I thought in parallel the capacitance would double (adds) to 0.44uf/450VDC.
470uf 250VDC is tough enough to find I thknk I will use that. Are those the biggest (physically) caps on this power supply?
Hi Navin,
220uF / 500 V electrolytic ( Samwah) is available freely.
Let me know if you have any problem getting them.
100u / 400 volt is also available and you just might get 450 volt types also. Typically 450 volt is the upper limit here but a few odd higher voltage ratings are available . You need to search out.
100 and 220 uF 450 volt is there. I bought a few.
Cheers.
220uF / 500 V electrolytic ( Samwah) is available freely.
Let me know if you have any problem getting them.
100u / 400 volt is also available and you just might get 450 volt types also. Typically 450 volt is the upper limit here but a few odd higher voltage ratings are available . You need to search out.
100 and 220 uF 450 volt is there. I bought a few.
Cheers.
navin,
it should be in series, not parallel. but what Tony said is that you parallel a 0.22/450 to C1 and another paralleled 0.22/450 to C2, thus the same effect.
if under chassis real estate is limited, I would suggest you get a single cap, instead of series caps to attain working voltage ratings. or another solution is to get upright caps which can be installed on top and save you some space under the hood.
cheers
it should be in series, not parallel. but what Tony said is that you parallel a 0.22/450 to C1 and another paralleled 0.22/450 to C2, thus the same effect.
if under chassis real estate is limited, I would suggest you get a single cap, instead of series caps to attain working voltage ratings. or another solution is to get upright caps which can be installed on top and save you some space under the hood.
cheers
A DIYaudio-brew EL34 amp 😉
I hope the first one will be born soon 😎
Another option for C1 is a 2 x 100uF/500V (dual) F&T Audio electrolytic (made in Germany)
Here's the link - http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=020-610
I hope the first one will be born soon 😎
Another option for C1 is a 2 x 100uF/500V (dual) F&T Audio electrolytic (made in Germany)
Here's the link - http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=020-610
it would be better to get all the parts first, then you can decide the final size. a good layout would be locating the 6sl7/6sn7 tubes farthest from the power transformer, and that there are at least 1.5 to 2 tube diameter separation between the EL34's.
layout all the transfomers and sockets on the table and move them around till you get the feel that you have a good lay-out. there are many on the web to get ideas from.
Tony, precisely the point. You wouldn't want to have a nice chassis only to find out you can't put in a cap or two, much worse the power transformer 😀
And it will be important to do a mock layout first when you get the parts.
I'm a fan of star grounding, but looking at the number of parts, it seems a T-bus is quite attractive.
edit:
I don't need another amp, buy hey, I have a quad of Svetlana EL-34, two pairs of Hitachi 6SN7, one pair of Electro-Harmonix 6SL7 - what the...
you guys just designed an amp out of my parts bin 😀 
And it will be important to do a mock layout first when you get the parts.
I'm a fan of star grounding, but looking at the number of parts, it seems a T-bus is quite attractive.
edit:
I don't need another amp, buy hey, I have a quad of Svetlana EL-34, two pairs of Hitachi 6SN7, one pair of Electro-Harmonix 6SL7 - what the...
you guys just designed an amp out of my parts bin 😀
ashok said:
I could fid 450VDC but nothing higher. At 450VDC I could find 100u and 220u. but thre was no 630V DC.
one option is to reduce the 450DC by have the power tranny secondary output at 310V instead of 340V required to 420VDC but that would require change in too many other parts (R20-24 in the amplifier schematic and R19, 21, 22 in the power supply schematic). Besides without the approval of experts like Wayne, Sy, etc.. I would not go anywhere near trying this. It was just thought.
arnoldc said:
Not only is brewed at diyaudio but almost built by the guys here too. Whenever it gets done this would be a labour of everyone on this thread. The list would be longer than the "I wish to thank..." list at any academy awards.
but dont hold your breath. with everything on my plate and the limited parts availability in India things take time.
Even the 6SL7 are being gifted (still not reached mumbai).
Tony said:
I was looking at a C-C distnace of about 4" (10cm) between any 2 tubes. I have considered and discarded a few layouts already.
arnoldc said:I'm a fan of star grounding, but looking at the number of parts, it seems a T-bus is quite attractive.
I don't need another amp, buy hey, I have a quad of Svetlana EL-34, two pairs of Hitachi 6SN7, one pair of Electro-Harmonix 6SL7 - what the...
T bus seems like it will get less in the way.
You only need 2 6SN7 and 1 6SL7 per amp. so really if you had 4 more EL34 you could build 2 amps provided you had the OPTs to match.
ray_moth said:
for 2 channels? 17x14! THat is huge. Only the Conrad Johnson MV60 is that big.
The Ella Consonance is much smaller.http://www.diyhifisupply.com/diyhs_ella.htm
http://www.jolida.com/catalogue/models/jd202a.shtml
12.5 inches (30 cm) wide by 12 inches (31 cm) deep by 8.25 inches (21 cm) high.
http://www.divaaudio.com/diva/divapower.html
this is the layout I prefer...
http://www.shinrock.com/DIY/EL34UL.html
navin,
my amp was built with a 14.5" width x 11" depth x 2" height custom built aluminium chassis.
http://img.photobucket.com/albums/v70/jojod818/JD Labs Tube Amp/JDL01.jpg
my amp was built with a 14.5" width x 11" depth x 2" height custom built aluminium chassis.
http://img.photobucket.com/albums/v70/jojod818/JD Labs Tube Amp/JDL01.jpg
JojoD818 said:
Thanks to the background the photo was a little unclear. I assume you have completed your layout.
Hello everyone, navin
A 220uF/500WV will work but... on power up the B+ will go slightly over 500V until the output tubes begin to conduct. The surge rating (depending on the particular cap used) IIRC will be around 550V. Now two 250V caps in series the surge rating IIRC will be 600V, 300V for each cap. So IMO I would go with the two 470uF/250WV route. The ESR will be higher but at the same time the surge rating will be higher and the caps will last longer. AND at the same time you could use a higher sec voltage and achieve a little higher B+ i.e. 450-470V with which you would obtain a higher output. IMO if you use a B+ higher than 440V as in 450-470V B+, lower the Iq from 35mA to 33mA accordingly. 😉
Also two 470uf 250WV will be easier to obtain and you will probably be able to find higher quality ones than a single 500WV unit. If you are concerned about the higher ESR you could use say 4x 220uf in series-parallel. In this situation you could use 350WV caps for a 700V capacitor bank!
IMO I don't think cathode stripping will be as great of concern using fixed bias as opposed to using self/cathode bias. But if it is of concern to you, go with some kind of soft-start as mentioned by SY in an earlier post. 😉
Cheers guys
Wayne
Edit: spelling.
A 220uF/500WV will work but... on power up the B+ will go slightly over 500V until the output tubes begin to conduct. The surge rating (depending on the particular cap used) IIRC will be around 550V. Now two 250V caps in series the surge rating IIRC will be 600V, 300V for each cap. So IMO I would go with the two 470uF/250WV route. The ESR will be higher but at the same time the surge rating will be higher and the caps will last longer. AND at the same time you could use a higher sec voltage and achieve a little higher B+ i.e. 450-470V with which you would obtain a higher output. IMO if you use a B+ higher than 440V as in 450-470V B+, lower the Iq from 35mA to 33mA accordingly. 😉
Also two 470uf 250WV will be easier to obtain and you will probably be able to find higher quality ones than a single 500WV unit. If you are concerned about the higher ESR you could use say 4x 220uf in series-parallel. In this situation you could use 350WV caps for a 700V capacitor bank!
IMO I don't think cathode stripping will be as great of concern using fixed bias as opposed to using self/cathode bias. But if it is of concern to you, go with some kind of soft-start as mentioned by SY in an earlier post. 😉
Cheers guys
Wayne
Edit: spelling.
cogsncogs said:
Hey Wayne, long time no see. How's everything at home.
1. Caps beyond 450V DC are not really available here. If I drop the tranny's secondary to say 310V instead of 340V I cold sneak by sing a 450VDC cap for C11 right? at the cost of having a B+ near 420-425V. Is this advisable? Iq would change, many resistors would change (both in the power supply and in the amplifier) etc...maybe i jsut use 2 450VDC caps for C11.
2. and no I am not concerned about higher ESR. lets be practical. The mor ethe components esp large caps the larger the box.
3. Yes I'd like to use a soft start only to protect the hard to come by tubes.
navin said:
the photo was meant to be unclear. 😀 seriously my digicam is just a cheapo one so nothing much to expect. this is my finished amp and not the one we are talking about here. my point is this amp uses tube rectification and choke which will also takes extra space in the amp. not to big and not too small is the word.
as for the caps, I suggest you go the 250V route like Wayne said, saving the life of caps for higher reliability. please do not lower your trannys secondary voltage too much just to accomodate your caps for you may need the extra voltage for future tweaks and upgrades to your amp.
Navin,
At present I read mail only every 2nd - 3rd day, so apology for sometimes late reply. Thanks for interest in my delay circuit (some posts ago; I am not going to retrace), but as I said, it forms integral part of other safety/control circuits specific to that amp. It is a simple Miller integrator feeding through the rest to a relay. (Mechanical device? - boooo! But it operates 4 independent DPST contacts; far too complicated to have done that semiconductor-wise.) It would need an extra low voltage supply (the relay is 12V) but perhaps I could scramble something up in the near future for your purpose.
Then I would also echo the use of serie PS capacitors (do remember the resistor chain for equal division of voltage; about 220K/1W each). Things can happen in the h.t. - pulses can come along, the mains is not constant, perhaps they work in a hot environment, etc. I have never really had audible improvement with values >100uF unless you stick your ear right into the loudspeaker, unless something else was wrong. But low frequency power could be affected.
Regards.
At present I read mail only every 2nd - 3rd day, so apology for sometimes late reply. Thanks for interest in my delay circuit (some posts ago; I am not going to retrace), but as I said, it forms integral part of other safety/control circuits specific to that amp. It is a simple Miller integrator feeding through the rest to a relay. (Mechanical device? - boooo! But it operates 4 independent DPST contacts; far too complicated to have done that semiconductor-wise.) It would need an extra low voltage supply (the relay is 12V) but perhaps I could scramble something up in the near future for your purpose.
Then I would also echo the use of serie PS capacitors (do remember the resistor chain for equal division of voltage; about 220K/1W each). Things can happen in the h.t. - pulses can come along, the mains is not constant, perhaps they work in a hot environment, etc. I have never really had audible improvement with values >100uF unless you stick your ear right into the loudspeaker, unless something else was wrong. But low frequency power could be affected.
Regards.
hi navin,
any word from your winder? you can ask him to add a secondary 12volt, 1A winding for your time delay relays. do you have 12volt dc relays or can get one or two?
any word from your winder? you can ask him to add a secondary 12volt, 1A winding for your time delay relays. do you have 12volt dc relays or can get one or two?
Navin,
If necessary, you can obtain 12v DC for your relay from a 6.3v winding, by using a voltage doubler circuit. The additional load on a heater winding is insignificant (< 300mA for a 100mA relay coil).
Just make sure the capacitors in the doubler (around 2200uF @25vDC) are sturdy enough to tolerate the currents, which can be quite severe. If the output from the voltage doubler under load turns out to be a bit high for the relays, you can adjust it with a smoothing resistor.
You can get a pretty good idea of what the capacitor currents and output voltage will be by using Duncan Amps PSUD2 simulator (free download).
If necessary, you can obtain 12v DC for your relay from a 6.3v winding, by using a voltage doubler circuit. The additional load on a heater winding is insignificant (< 300mA for a 100mA relay coil).
Just make sure the capacitors in the doubler (around 2200uF @25vDC) are sturdy enough to tolerate the currents, which can be quite severe. If the output from the voltage doubler under load turns out to be a bit high for the relays, you can adjust it with a smoothing resistor.
You can get a pretty good idea of what the capacitor currents and output voltage will be by using Duncan Amps PSUD2 simulator (free download).
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