Hello all:
I have a question regarding the output transformer options; I have a nice set of 8k transformers salvaged from an Ampex 6973 30w amp. Will these work on this project. how do I choose the correct tube to optimize these transformers. I would like to use a 6ca7 or 6v6 if I can with these transformers.
Thanks for the help
I have a question regarding the output transformer options; I have a nice set of 8k transformers salvaged from an Ampex 6973 30w amp. Will these work on this project. how do I choose the correct tube to optimize these transformers. I would like to use a 6ca7 or 6v6 if I can with these transformers.
Thanks for the help
They will work fine. You might get a slight loss in power but also a decrease in distortion due to the higher impedance. But they are good quality outputs🙂
wow that was quick!
Thanks, I am not overly concerned about power anything above 10watts is likely to be plenty for me. Of the possible octal tubes which will be best matched to a 30Watt 8K output transformer.
Thanks, I am not overly concerned about power anything above 10watts is likely to be plenty for me. Of the possible octal tubes which will be best matched to a 30Watt 8K output transformer.
6V6GT would work fine for those power levels. But you could also use 6L6 or EL34 for a few more watts...
I am using some 7.6k outputs with el34's.
I am using some 7.6k outputs with el34's.
Hi SCD & meanman1964,
Regarding output transformer optimum primary impedance are depending of output tubes of course, but these tubes are very tolerant and will accept some variations without any problem other than some lower output power as mctavish says 🙂
As a suggestion indicated in the BOM, commonly used impedances are as follow :
6V6 will use 8k OTP 15W
6L6 or KT66 will use 6.6k OPT 25W
EL34. 6CA7, KT88, 6550, etc... use in general 4.3k OTP 50W, but Toroid suggest the EL34PP which is specified at 6.6k while Hammond suggest the 1650N which is 4.3k, that's why I suggested to use the KT88PP specified at 4k also for EL34...
Hi mctavish,
Nice and quick work, be careful with the MOSFET in the bottom to connect them correctly !
Rgds,
Marc
Regarding output transformer optimum primary impedance are depending of output tubes of course, but these tubes are very tolerant and will accept some variations without any problem other than some lower output power as mctavish says 🙂
As a suggestion indicated in the BOM, commonly used impedances are as follow :
6V6 will use 8k OTP 15W
6L6 or KT66 will use 6.6k OPT 25W
EL34. 6CA7, KT88, 6550, etc... use in general 4.3k OTP 50W, but Toroid suggest the EL34PP which is specified at 6.6k while Hammond suggest the 1650N which is 4.3k, that's why I suggested to use the KT88PP specified at 4k also for EL34...
Hi mctavish,
Nice and quick work, be careful with the MOSFET in the bottom to connect them correctly !
Rgds,
Marc
I've the change of buying these for a good price
TTG-6AS7PP - Tube output transformer [5kOhm] 2x6AS7G / 2x6N13S Push-pull or similar - Shop Toroidy.pl
TTG-6AS7PP - Tube output transformer [5kOhm] 2x6AS7G / 2x6N13S Push-pull or similar - Shop Toroidy.pl
hello Marc:
perhaps my question was unclear. I already have the output transformers. I am curious as to what tube I should chose to optimize the potential of the transformer, rather than deciding on the tube and choosing a transformer to optimize the tube. From your response, I gather you think the best tube for these transformers will be a 6v6? Are there other tubes that are optimized with an 8k load.
Thanks for the help
perhaps my question was unclear. I already have the output transformers. I am curious as to what tube I should chose to optimize the potential of the transformer, rather than deciding on the tube and choosing a transformer to optimize the tube. From your response, I gather you think the best tube for these transformers will be a 6v6? Are there other tubes that are optimized with an 8k load.
Thanks for the help
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Really that impedance is perfect for the 6L6 family. You would have a wide choice of power tubes. KT66, 5881, & many 6L6 brands....I believe those transformers were made by Triad. The end bells are painted gray? Very High quality xmers.
Hello Crispy:
Thanks for the suggestion.
Yes the transformers were made by Triad. The end bells were black rather than grey. As noted earlier, they were wound for Ampex in a PP 6973, 30watt console stereo. I got the salvaged amp as a gift from a neighbour. I plan on using the power transformer and the output transformers in this amp project.
I will investigate the 6L6 family as you suggest.
Thanks for the suggestion.
Yes the transformers were made by Triad. The end bells were black rather than grey. As noted earlier, they were wound for Ampex in a PP 6973, 30watt console stereo. I got the salvaged amp as a gift from a neighbour. I plan on using the power transformer and the output transformers in this amp project.
I will investigate the 6L6 family as you suggest.
Hi SCD,
The 6L6 family is my favorite, so it would be a good choice. I've seen them used for everything from 20 wpc amplifiers up to 50 wpc amplifiers.
-Chris
The 6L6 family is my favorite, so it would be a good choice. I've seen them used for everything from 20 wpc amplifiers up to 50 wpc amplifiers.
-Chris
Hello mctavish:
It looks like it is going to be tight squeeze.
I like tubes up front, so #1 or #2.
You might also consider two separate chassis. It is a bit of a pain in the butt with double everything and separate volume controls, but that chassis you have might be a little too tight. Check real close before you start drilling and cutting.
It looks like it is going to be tight squeeze.
I like tubes up front, so #1 or #2.
You might also consider two separate chassis. It is a bit of a pain in the butt with double everything and separate volume controls, but that chassis you have might be a little too tight. Check real close before you start drilling and cutting.
Yup, tight fit. It is 14'' x 17'' though, the biggest I could get...
I will have to sleep on it and have another look tomorrow🙂
I will have to sleep on it and have another look tomorrow🙂
Mctavish is way a head of me and looking good. I'm really gonna enjoy watching everyone's build & concept. I bet he dreams about it in his sleep...
Hi All, does anyone know how the feedback 1 &2 pin connect to where and what component and for what function
The feedback input can be used with a connexion to the secondary of the output transformer in case of instability, in my case I have not used it 🙂
It can also be used for a differential input in this case use the same value like the input ones !
Marc
It can also be used for a differential input in this case use the same value like the input ones !
Marc
And I did dream about it!!! 😀
I think I am going to go with option 3, it provides the most space between the output transformers and the power transformers and it keeps the connections close.
The chassis is 4'' x 14'' x 17'' so its quite big, the biggest that Hammond offers.....
The whole thing will be Quite heavy when done!!!😱
Today the holes are going in the chassis!!!
I think I am going to go with option 3, it provides the most space between the output transformers and the power transformers and it keeps the connections close.
The chassis is 4'' x 14'' x 17'' so its quite big, the biggest that Hammond offers.....
The whole thing will be Quite heavy when done!!!😱
Today the holes are going in the chassis!!!
mctavish, since you have all of that, add in a couple of plugs, and another chassis, why not just make a pair of mirrored L-R monoblocks?
That way you can save the current chassis you have for another project.
That way you can save the current chassis you have for another project.