OK, but 1.75 is again small for EL34 in triod. /You can, IMO, multiply inner resistance to more 3 times to define load to avoid distortions for High quality/.
But choice is yours..../I use 3-5 times/.
But choice is yours..../I use 3-5 times/.
Optimum load impedance depends on plate voltage and - current.
High voltage, low current: high Rload is optimum.
Low voltage, high current: low(er) Rload is optimum.
High voltage, low current: high Rload is optimum.
Low voltage, high current: low(er) Rload is optimum.
Hello,
My first idea was a gu50 push-pull amp.
But supply voltage must be at least 400 v.
A transformer who can supply 400v is not common and expensive.
Then i readed that a 3,5k load works with tubes suchs 6080 6as7g 6n13s ...
But with one triode it will be weak.
I calculate 8,5w for one triode,(65% max power of one triode with B+=250v)
So that is 17w per chanel.
Two tubes (2 triodes in one tube) give around 25w per chanel.(6,5w for one triode with B+=300v).
With one cheap insulating transformer (230v/230v) i think it will work.Is it right ?
My first idea was a gu50 push-pull amp.
But supply voltage must be at least 400 v.
A transformer who can supply 400v is not common and expensive.
Then i readed that a 3,5k load works with tubes suchs 6080 6as7g 6n13s ...
But with one triode it will be weak.
I calculate 8,5w for one triode,(65% max power of one triode with B+=250v)
So that is 17w per chanel.
Two tubes (2 triodes in one tube) give around 25w per chanel.(6,5w for one triode with B+=300v).
With one cheap insulating transformer (230v/230v) i think it will work.Is it right ?
Marco, it would be best if you tell us what you are trying to do. There are many possible answers.
Do you have a pair of 3.5k/50W OPT and do you want to design and build a pair of amps using them? What other restrictions/parameters do you have? For example, I don't understand your remark about the power transformer. What is so unusal about 400V?
To add to the possible list: PPP 6L6 cathode bias, 400-450V B+ will give you about 50W with those OPTs.
Are you going to design these amps or do you want to use an existing design?
Do you have a pair of 3.5k/50W OPT and do you want to design and build a pair of amps using them? What other restrictions/parameters do you have? For example, I don't understand your remark about the power transformer. What is so unusal about 400V?
To add to the possible list: PPP 6L6 cathode bias, 400-450V B+ will give you about 50W with those OPTs.
Are you going to design these amps or do you want to use an existing design?
dgta,
Agreed.
Start with what the amp needs to do.
Marco audio,
This is for a Hi Fi Amp, not a Guitar Amp, Right?
Agreed.
Start with what the amp needs to do.
Marco audio,
This is for a Hi Fi Amp, not a Guitar Amp, Right?
A purpose built "vacuum tube" power transformer is somewhat expensive. A 230 to 230 volt isolation transformer can sometimes be found for cheap. A small 6 or 12 volt transformer can be used for the heaters.
The B+ voltage for a silicon rectified 230 volt secondary is about 300 to 340 volts depending on the actual line voltage.
320 volts into a pair of decent sized TV sweep (line output) tubes can make for a good HiFi amp and most are far more linear than 6AS7's.
There's always the good old 2A3. Only about 8 watts per channel in class A, but it's a classic. An OPT with 3.5k plate-plate primary is pretty common for PP 2A3s.
Also, what about push-pull EL86?
Both of the above don't require higher than 300V Ebb.
--
Also, what about push-pull EL86?
Both of the above don't require higher than 300V Ebb.
--
If one has the $$$ for DHT's, then they probably can swing a proper power transformer, but a pair of 2A3's on 300 volts can do 20 watts in AB1, and over 25 watts in AB2 with a 3.5 K OPT.
In fact the old 45 can do about 20 watts per pair in AB2.
A pair of 6CW5/EL86 can do nearly 30 watts into a 3.3K ohm OPT on 330 volts of B+ and about 170 to 200 volts on G2. Slightly less power will be available with a 3.5K OPT. The UL84 / 45B5 is a 45 volt version of the same tube, it is not a 45 volt EL84.
You have understand me
I buyed those transformer for few euros and i get some electronic junks and cheap tubes.
You have understand me
I buyed those transformer for few euros and i have some electronic junks and cheap tubes.
Tubes EL36 (6CM5), E236L, EL360, EL500 / EL504 (6GB5), E235L (7751), 6DQ6A (or B), or PL36 (25E5), 25DQ6A can with output transformer (~ 3.5kOhms plate to plate) with Ua ~ 300V and Ug2 ~ 150-200V (stabilized if possible) give more than ~ 40W output power. Probably with a larger number of cheap tubes used in the horizontal output stages of a B / W TV, similar results can be obtained, but I have worked with the above tubes and I can verified that they will work well, long and stably.
There is a relatively cheap offer of Russian replacements on e-Bay for some of the listed tubes, which also work well.
There is a relatively cheap offer of Russian replacements on e-Bay for some of the listed tubes, which also work well.
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From TME (Poland) you can get very versatile TSL-180 power transformer. It has 4 pcs. 300 mA windings for +Ub: 205 V, 115 V, 30 V and 20 V. By combining these you get suitable supply voltage for many different output tubes.
TSL 180/001 INDEL - Transformer: mains | 230VAC; 205V; 70V; 30V; 115V; 20V; 2V; 3.2V; 3.2V; TSL180/001 | TME - Electronic components
Hello Thanks for your reply.
That's an idea! It works for one chanel.(a chanel will work near 300ma.
I can build two mono blocks .
6N8S as amplifier and phase spliter ,then drivers.
A classic schematic, isn't it ?
I know Tme .They sell Toroidy transformers and other good products.Fast shipping with tracking.
That's an idea! It works for one chanel.(a chanel will work near 300ma.
I can build two mono blocks .
6N8S as amplifier and phase spliter ,then drivers.
A classic schematic, isn't it ?
I know Tme .They sell Toroidy transformers and other good products.Fast shipping with tracking.
Is this for GU50 triode or for what tubes ?
There is also more powerful version Indel TSL-400. It has 313 V / 600 mA secondary, which produce some 420...430 Vdc.
TSL 400/001 INDEL - Transformer: mains | 230VAC; 168V; 313V; 28V; 10.5V; 6.4V; 6.4V; 69V; TSL400/001 | TME - Electronic components
It's for a push-pull gu50 triode.
Is it wrong ?
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Of course here they are the maximal conditions.
But i'm carefully.
Is it wrong ?
Of course here they are the maximal conditions.
But i'm carefully.
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That is a great tip, thanks! I was wondering about the 2V 6A winding - how can that be used? It could be combined with a 3.2V winding, but then there would be no 6.3V possibility.
Even so, a good fit for the Baby Huey EL84, and ideal for winter projects with old TV tubes.