Lowrider said:This forum has a lot of very knowledgeable people, but they simply ignore you if you dont do as they say...
So what?
If they ignore me I ignore them.
Back to the topic: do you know how to obtain curves from your exact tube instead of reading about a theoretical round horse in vacuum and how to reshape it into a real tube?
Anatoliy,
I have 3 variable DC power supplies, 2 of them are Heathkit IP-17's, Tektronix 2465 oscilloscope, audio generators, meters and any other test equipment needed.
I never plotted curves so if you give me an idea how to do it I can build a test jig on my bench and go at it. This is very interesting.
Thanks,
Sal
I have 3 variable DC power supplies, 2 of them are Heathkit IP-17's, Tektronix 2465 oscilloscope, audio generators, meters and any other test equipment needed.
I never plotted curves so if you give me an idea how to do it I can build a test jig on my bench and go at it. This is very interesting.
Thanks,
Sal
Bernardo:
Hi........Just down south of you here in Argentina, I am still trying to find a transformer manufacturer in country that will make a 'special order' for me...I have designed an 813 Single ended amp but the transformers would be imported....as my wife (Argentinian born) points out to me, the importing of said transformers will drive the price way out of reason.
That said, when we came here we brought our appliances which were 220VAC but the distribution was different requiring a large transformer for our clothes dryer. The KEY was this transformer was a custom made 220VAC-220VAC isolation type with a center tap on the secondary. This transformer is Appx 200 mm high, 300mm wide,300mm deep...at 20? Kilos'.
It was 'made' for appx. 1200 Pesos. This monster is priced just fine considering the Peso to dollar conversion rate!
This great pricing is what got me to consider building tube amps in the first place. Look up www.kaizenelectronica.com.ar they won't respond to my E-mails....perhaps we can work together to find suitable LOCAL manufacturers.
_______________________________________Rick...........
Hi........Just down south of you here in Argentina, I am still trying to find a transformer manufacturer in country that will make a 'special order' for me...I have designed an 813 Single ended amp but the transformers would be imported....as my wife (Argentinian born) points out to me, the importing of said transformers will drive the price way out of reason.
That said, when we came here we brought our appliances which were 220VAC but the distribution was different requiring a large transformer for our clothes dryer. The KEY was this transformer was a custom made 220VAC-220VAC isolation type with a center tap on the secondary. This transformer is Appx 200 mm high, 300mm wide,300mm deep...at 20? Kilos'.
It was 'made' for appx. 1200 Pesos. This monster is priced just fine considering the Peso to dollar conversion rate!
This great pricing is what got me to consider building tube amps in the first place. Look up www.kaizenelectronica.com.ar they won't respond to my E-mails....perhaps we can work together to find suitable LOCAL manufacturers.
_______________________________________Rick...........
Attachments
Ok. 222.7 is VOLTAGE, not CURRENT.
It is an effective voltage while an amplitude is 1.42 times higher.
What maximum power dissipation you may allow for your output tube?
George (tubelab.com) have plenty of them so he tortures tubes to see if they are alive on certain power; if you have only few of them you probably have to trust the manufacturer that specifies the max power, right?
So, how much are you going to dissipate?
It is an effective voltage while an amplitude is 1.42 times higher.
What maximum power dissipation you may allow for your output tube?
George (tubelab.com) have plenty of them so he tortures tubes to see if they are alive on certain power; if you have only few of them you probably have to trust the manufacturer that specifies the max power, right?
So, how much are you going to dissipate?
Richard Ellis said:
The idea was, to get a SE sound from a PP transformer. It will be even better than SE because the transformer needs to be smaller, with less of iron and copper (both are expensive in South America and in China, right?), so capacitance between windings will be smaller, the same about stray inductance. You'll get a sound from a PP amp similar to a sound from SE amp that is not practically possible if to use an "inside of the box" approach. My approach is to go out of the box and look from outside.
You'll need also an opamp to drive a FET. do you have some?
Ok, do you have a BJT from an old TV?
MOSFET is what come to my mind because of availability.
Do you have a BJT that was used for horizontal deflection in an old TV?
They usually survive high enough voltage that is needed for vacuum tubes.
PN junctions on high voltages (ANY PN JUNCTIONS!) work like Zener diodes: from some point they start conducting. It means, a transistor is a transistor until you supply it with a certain voltage, after that it is a Zener diode!!!!
Back in 1970'th I used to select transistors for my custom amps from devices that were rated for 25V when I need more than 100 Volts.
Do you have an idea how to measure your transistors?
MOSFET is what come to my mind because of availability.
Do you have a BJT that was used for horizontal deflection in an old TV?
They usually survive high enough voltage that is needed for vacuum tubes.
PN junctions on high voltages (ANY PN JUNCTIONS!) work like Zener diodes: from some point they start conducting. It means, a transistor is a transistor until you supply it with a certain voltage, after that it is a Zener diode!!!!
Back in 1970'th I used to select transistors for my custom amps from devices that were rated for 25V when I need more than 100 Volts.
Do you have an idea how to measure your transistors?
Gentlemen;
if you have any questions please ask.
I am aware that nobody knows analog electronics like me it is not a shame because I myself don't know everything, and the more I know the more I understand how much don't I know; so please don't hesitate and ask. If both of us don't understand I'll learn together with you continuing the discussion. We'll gain both.
if you have any questions please ask.
I am aware that nobody knows analog electronics like me it is not a shame because I myself don't know everything, and the more I know the more I understand how much don't I know; so please don't hesitate and ask. If both of us don't understand I'll learn together with you continuing the discussion. We'll gain both.
Gentlemen,
This looks like fun! Can I just use rubber gloves rather than using one hand with the other behind my back (fingers crossed of course)?
I like the idea of a Russian-American DIY Tube amp over a Chinese one!
We covet a lot of electronic components from Russia anyway and quite a few of their tubes! So this is a worthy undertaking and I hope to learn too!
Thanks guys!
Regards//Keith
This looks like fun! Can I just use rubber gloves rather than using one hand with the other behind my back (fingers crossed of course)?
I like the idea of a Russian-American DIY Tube amp over a Chinese one!
We covet a lot of electronic components from Russia anyway and quite a few of their tubes! So this is a worthy undertaking and I hope to learn too!
Thanks guys!
Regards//Keith
Bernardo,
Talk to Eduardo at Audio Pax. He builds excellent tube amps and he is in Brazil. His web site is www.audiopax.com. He should be able to help you out.
Talk to Eduardo at Audio Pax. He builds excellent tube amps and he is in Brazil. His web site is www.audiopax.com. He should be able to help you out.
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