| camotecue |
| this is my first time posting here. i have a pair of 6SN7GTBs and a pair of 6V6GTY tubes. i want to try building a SET amp preferably tube rectified using 5U4G. i'm looking for good schematic i can use. can anyone please help me? |
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| Roscoe Primrose |
See: 12at7->6aq5 amp the 6AQ5 is electrically very similar to the 6V6, just can't handle quite as much plate voltage... Also 6SN7 -> 6550 amp
Neither of these is exactly what you're looking for, but there a good starting point...
Peace |
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| camotecue |
| thanks for the reply. can't seem to open the suggested sites though. |
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| Eli Duttman |
What sort of speakers are you planning to use the amp with? SE and triode strapped, a 6V6 will yield about 3 W. IMO, 98 dB. SPL speakers are indicated for 3 WPC amplification.
You could squeeze about 5 W. out of a 6V6 if it's wired UL SE. 95 dB. SPL speakers enter the picture at 5 WPC.
Cascaded common cathode gain blocks will give you plenty of drive. Don't forget a decoupling filter in a 3 stage amp. Perhaps a DC coupling expert will help in setting up the 'SN7s; that would leave only 1 cap. (between the driver and 6V6) in the signal path.
BTW, I tried the links Mr. Primrose provided. I get a page unavailable notification. |
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| fdegrove |
Hi,
| quote: | | I get a page unavailable notification. |
Just the way the thing is coded so use the frontdoor:
MATHIJS
Cheers,;) |
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| camotecue |
| quote: | Originally posted by Eli Duttman
What sort of speakers are you planning to use the amp with? SE and triode strapped, a 6V6 will yield about 3 W. IMO, 98 dB. SPL speakers are indicated for 3 WPC amplification.
You could squeeze about 5 W. out of a 6V6 if it's wired UL SE. 95 dB. SPL speakers enter the picture at 5 WPC.
Cascaded common cathode gain blocks will give you plenty of drive. Don't forget a decoupling filter in a 3 stage amp. Perhaps a DC coupling expert will help in setting up the 'SN7s; that would leave only 1 cap. (between the driver and 6V6) in the signal path.
BTW, I tried the links Mr. Primrose provided. I get a page unavailable notification. |
thank you for the replies. i'm currently using an 8" single full range driver in a voigt pipe. my current amp which is a 2A3 can easily drive it to loud levels. just wanted to utilize these spare tubes. i already have a 6V6 push-pull amp so i wanted to build a another 6V6 amp but in a SET config. |
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| planet10 |
| found on my hard drive... |
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| planet10 |
| more... 12AX7 + 6V6 |
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| ShiFtY |
If you are into experimentation (!) maybe try it in pentode mode with a little negative feedback. I made one sound very good using this method.
6V6s are great tubes, better than those christmas-tree-light 6AQ5s! And they can easily handle 12W or more dissipation (5W audio in pentode mode) |
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| Eli Duttman |
camotecue,
You have high efficiency speakers. So, triode strapped 6V6s will be fine.
Build a stereoblock from the schemo planet10 provided. Save the extra 6SN7 for the future, but you will replace the 6V6s long before the driver wears out. |
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| zobsky |
planet10's schematic and my link are the same , ... the link i posted earlier gives you some background into the design process and construction, .. always useful for beginner.
cheers:drink: |
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| camotecue |
| thank you all guys for contributing to my query. it may be difficult to find 5Y3 tubes here in the Philippines. can you please help me design the power supply of the triode strapped-schematic as posted here in this thread by using 5u4g tube instead. |
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| camotecue |
| quote: | Originally posted by ShiFtY
If you are into experimentation (!) maybe try it in pentode mode with a little negative feedback. I made one sound very good using this method.
6V6s are great tubes, better than those christmas-tree-light 6AQ5s! And they can easily handle 12W or more dissipation (5W audio in pentode mode) |
hello shifty! can you please post the schematic of your pentode mode-design so i can compare? did you use 6SN7 tubes also as the driver and 5u4g rectifier tube? thanks |
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| arnoldc |
| quote: | Originally posted by camotecue
thank you all guys for contributing to my query. it may be difficult to find 5Y3 tubes here in the Philippines. |
camotecue, we have soooo many 5Y3. you just need to look at the right place, but if you like i can buy for you (cheaper, he he) |
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| ShiFtY |
5U4 and 5Y3 are pretty much the same, 5U4 has a 3A filament and can handle more B+ current. If your 5V filament winding can handle it, you can plug a 5U4 straight in.
Sorry no schematic, but the 1/2 12ax7 -> 6v6 posted earlier is pretty much identical. Just change the preamp anode and cathode resistors to suit 1/2 a 6SN7 instead of 12AX7. |
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| camotecue |
| quote: | Originally posted by arnoldc
camotecue, we have soooo many 5Y3. you just need to look at the right place, but if you like i can buy for you (cheaper, he he) |
ah ok sir! please help me buy a 5y3 tube. i'll start buying the parts for the amp. |
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| arnoldc |
5Y3 drops 60V compared to 45V of 5U4. in my 45 amp it was quite critical and i needed the 5Y3 because i goofed in the power transformer :xeye:
camotecue, how many do you need? 2 pcs? |
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| camotecue |
| i think the single ended triode strapped 6V6 amp schematic in this thread requires only a single 5y3. |
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| Eli Duttman |
Instead of an "ordinary" 5Y3, spend a little extra and buy a 6087/5Y3WGTB. The 6087 has a cathode sleeve. The IDH signal tubes will last longer with a slow B+ rise. Prevent cathode stripping.
A 5V4 is another suitable 1/2 indirectly heated rectifier. The forward voltage drop in a 5V4 is less than that in a 5Y3. |
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| camotecue |
| quote: | Originally posted by Eli Duttman
Instead of an "ordinary" 5Y3, spend a little extra and buy a 6087/5Y3WGTB. The 6087 has a cathode sleeve. The IDH signal tubes will last longer with a slow B+ rise. Prevent cathode stripping.
A 5V4 is another suitable 1/2 indirectly heated rectifier. The forward voltage drop in a 5V4 is less than that in a 5Y3. |
Eli Duttman,
do i have to change the values of the any of the parts in the power supply should i use 5Y3WGTB rather than 5y3 only? |
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| arnoldc |
i am not Eli but i would say no. am i right Eli? :D and i'd say go for slow start rectifiers, or put in a stand by switch (which is mostly what i do). you don't have to limit your tube rectifier choices, find one that is slow start and which you will have a budget for, because 5AR4's are ridiculously high priced in the philippines. 5Y3 and a stand by switch a lot cheaper :D :D :D
once you have sorted out your choice, then we can design the PSU around that using PSUD. ;) |
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| Eli Duttman |
6087/5Y3WGTB replaces an "ordinary" 5Y3 without any circuit changes. Same story for the 6106. A 5Y3 with a slow B+ rise is nice. I use Raytheon 6087s in my DECWEAR SE84Bs, whose circuitry is also triode/triode strapped pentode.
If you use a 5V4, you will have to allow for a higher B+ rail voltage.
A way to get the slow B+ rise CHEAP is to use 2X 7Y4 Locktal tubes. In the US, Locktal sockets cost more than 7Y4s and 7Z4s do. |
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| Lico |
The first schematic planet10 posted is the one i built. here's the ps for it. Enjoy.
Andy |
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| Roscoe Primrose |
| quote: | Originally posted by Lico
The first schematic planet10 posted is the one i built. here's the ps for it. Enjoy.
Andy |
You may want to re-think that, the 5V4 is rated for 10uF max for the first stage of a cap input filter...
Peace |
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| ShiFtY |
^^ Not according to the data I have... 32uF is the max input capacitance. 10uF is suggested, but you can use more as long as you don't go over peak current ratings. I would suggest something like 22uF for a 5V4.
Check this:
http://www.mif.pg.gda.pl/homepages/...t/001/5/5V4.gif
I use a Mullard GZ32, the nicest rectifier around! It is a 5V4 equiv. |
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| G |
| This is the Schematic of my SE EL84 amp. You will have to change the biasing of the output stage a little to use a 6V6 but everthing else should be the same. I'm king of busy today otherwise I would do the calculations for you and post them. Sorry. |
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| G |
| My apologies. THis is the correct schematic. Oops. |
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| camotecue |
| i decided to go for a 5u4g rectifier. i'll be using a power transformer rated at 300-0-300. can anyone please help me design the power supply if i require 250V B+ for the 6V6 and 180V for the 6sn7 driver. thanks |
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| Eli Duttman |
| A choke I/P filter should put you quite close to 250 VDC. The rectifier feeds a LC section plus bleeder resistor. Follow the 1st LC section with 2X LC sections, 1/channel for good separation. A RC section for each driver plate finishes things off. |
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| camotecue |
| quote: | Originally posted by Eli Duttman
A choke I/P filter should put you quite close to 250 VDC. The rectifier feeds a LC section plus bleeder resistor. Follow the 1st LC section with 2X LC sections, 1/channel for good separation. A RC section for each driver plate finishes things off. |
thanks eli. but as a newbie (please pardon my ignorance), i cant quite understand what you've just mentioned. i would really appreciate if you could put it in schematic form. |
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| arnoldc |
camotecue,
you said you need a voltage drop of 70V (250-180) and we need the current drain of that stage to compute for the dropping resistor.
if it is 2mA for example, then R = 70V / 0.002A = 35Kohm
i can draw you a schematic as suggested by eli, later.
we will also need the current drain of the power stage to compute for the power supply.
here is the schematic.... it does not include the RC section which would be B+ (from the diagram) ---R (?)--- C (47uF) ---> driver for each channel... oh and i forgot the bleeder on the first cap :xeye: |
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| camotecue |
| quote: | Originally posted by arnoldc
camotecue,
you said you need a voltage drop of 70V (250-180) and we need the current drain of that stage to compute for the dropping resistor.
if it is 2mA for example, then R = 70V / 0.002A = 35Kohm
i can draw you a schematic as suggested by eli, later.
we will also need the current drain of the power stage to compute for the power supply.
here is the schematic.... it does not include the RC section which would be B+ (from the diagram) ---R (?)--- C (47uF) ---> driver for each channel... oh and i forgot the bleeder on the first cap :xeye: |
thanks for your help. do i see three (3) 10H chokes? |
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| arnoldc |
| yes, you do. the value (10H) is a suggestion and what i mostly use. the 5U4G manual also lists that as a typical value if i'm not mistaken. |
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| Eli Duttman |
Better than 3 10 H. chokes is a 20 H. choke in the 1st position and 2X 5 H. in the 2nd position. A 10 KOhm bleeder resistor is used with a 10 H. choke, while a 20 KOhm bleeder resistor is used with a 20 H. choke. A larger 1st inductor allows you to lower the I^2R losses (heat) in the bleeder resistor.
BTW, an inductor rated for choke I/P service is required in the 1st position. "Beefy" construction is in order to cope with the large AC ripple current that is present. The chokes used in the 2nd position can be of the "ordinary" variety. |
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| ShiFtY |
Or you could just use something like 20uF-10H-47uF and you would be right. Modelling this in PSUD gives a very smooth power supply.
Voltage would be higher, at around 320V, but you can boost your cathode resistors on the 6V6s to compensate, so you don't go over the plate dissipation rating (12W I think?)
Three chokes is excessive, IMHO. :) |
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| Eli Duttman |
| quote: | | Three chokes is excessive, IMHO. |
You're going against long established precedent. Older editions of the ARRL Handbook specifically advise that 2 LC sections in cascade be used when choke I/P filtration is employed.
Using a pair a LC sections after the 1st LC section isolates the 2 channels from each other. It's a form of pseudo dual mono power supplies.
CLC supplies are POORLY regulated, while choke I/P supplies are WELL regulated. Another advantage of choke I/P filtration is the ability to access the full VA capability of the power trafo. |
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