Check my transformer math here:
Battery Powered Tube Amplifier : 4 Steps (with Pictures) - Instructables
I think it is exactly the transformer Kay Pirinha suggested.
Battery Powered Tube Amplifier : 4 Steps (with Pictures) - Instructables
I think it is exactly the transformer Kay Pirinha suggested.
Yes, this appears to be the same as, or at least similar to the Visaton TR10.16.
Best regards!
Best regards!
And that tube might be fine with a 100 dB 12" but used with an inefficient speaker you will bu constantly in distortion. It was not ment to be an output tube. But it is part of the learning experience I guess. Some wise words from PRR
THE SFA - 1W all tube guitar amplifier
Hi,
I think I will go with one of those that you've suggested:
Either the Omnitronic ELA-T5 or the Visaton TR10.16. It would be nice to find them here in the UK.
Cheers,
Pedro
PS: Out of curiosity, are you Brazilian? Kay Pirinha and Caipirinha sound similar
Well spottet on the drink 
! But I can assure you that I'm plain German .
As I said previously (did I really?), I suppose there are other manufacturers in the whole wide world that might make similar or identical transformers as Omnitronic or Visaton.
Btw, my suggestions aren't identical. The Visaton is a 10 W transformer, hence somewhat bigger than the Omnitronic. There's a 10 watts Omnitronic T-10 as well, though, but I wouldn't suggest it here, as it's lowest wattage is 1.25 W, hence transforms to 8 kohms.
Omnitronic ELA transformers datasheet
Best regards!
! But I can assure you that I'm plain German .As I said previously (did I really?), I suppose there are other manufacturers in the whole wide world that might make similar or identical transformers as Omnitronic or Visaton.
Btw, my suggestions aren't identical. The Visaton is a 10 W transformer, hence somewhat bigger than the Omnitronic. There's a 10 watts Omnitronic T-10 as well, though, but I wouldn't suggest it here, as it's lowest wattage is 1.25 W, hence transforms to 8 kohms.
Omnitronic ELA transformers datasheet
Best regards!
Have you seen this web site? http://home.alphalink.com.au/~cambie/6AN8amp/M1115.htm Also many 100v line transformers on eBay.
Do not be fooled by the 0.25W output. It is loud with a good speaker. A small speaker will give you ear piercing highs, which is also very loud if you are playing in your living room, which I guess, is what all the musicians are doing at the moment.
The SFA is based on the JJ SE amplifier (or the zvex nano head):
The Superfly uses a self-split PP output stage (same output power, but can use a smaller PP transformer, which has no air gap, smaller core for same inductance and less noise):
My previous research also revealed a french version (I think it uses a cathodyne to have a proper PP stage, but is cleaner because of the missing gain stage the superfly has):
[Ampli] Le микроб : SECTION LAMPES - MONTAGES HYBRIDES - .: www.Techniguitare.com :. Le portail du DIY Francophone
I would say, that depending on where you are located you can get cheap trasnformer from reichelt.de. I don't know how the Brexit thing affects this. On the other hand the UK also has lots of large component stores where those line transformers can cost less than 10 pounds. They are definetely cheaper than Ebay, but then on ebay you can find old radio transformer, which might be better or worse than the line transformer.
Once you have a transformer, the rest os OK. The 555 SMPS can deliver the required current at 200V (in PP you can also use higher voltages than in SE!).
The SFA is based on the JJ SE amplifier (or the zvex nano head):
The Superfly uses a self-split PP output stage (same output power, but can use a smaller PP transformer, which has no air gap, smaller core for same inductance and less noise):
My previous research also revealed a french version (I think it uses a cathodyne to have a proper PP stage, but is cleaner because of the missing gain stage the superfly has):
[Ampli] Le микроб : SECTION LAMPES - MONTAGES HYBRIDES - .: www.Techniguitare.com :. Le portail du DIY Francophone
I would say, that depending on where you are located you can get cheap trasnformer from reichelt.de. I don't know how the Brexit thing affects this. On the other hand the UK also has lots of large component stores where those line transformers can cost less than 10 pounds. They are definetely cheaper than Ebay, but then on ebay you can find old radio transformer, which might be better or worse than the line transformer.
Once you have a transformer, the rest os OK. The 555 SMPS can deliver the required current at 200V (in PP you can also use higher voltages than in SE!).
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Thanks for the suggestions Thomas.
Sometime ago I've come across this amazing website, which pointed me to several projects:
Subminiature Tubes - monster.party.hat
So now the question is what to build? I like the Super Fly, to be honest and maybe this will be the one to build.
Well, I have been talking about a tiny 4 ohm speaker, but I totally forgot that I can use my Marshall's Valvestate 8080 speaker as well.
This is a 12'' 8 ohm Eminence speaker. Basically, I could use the sub-mini amp as a head for the Marshall's speaker, I guess.
In this case, would it be better class A or AB?
I've read somewhere that class AB delivers more power than class A (3x more).
But isn't the difference only in the time the tubes conduct? So in class A there is only one tube, so it conducts 100% of the time, whereas in class AB each tube conducts for ~50% of the time.
But this doesn't mean that more power is delivered to the speaker, right? Or am I wrong?
Best regards,
Pedro
Sometime ago I've come across this amazing website, which pointed me to several projects:
Subminiature Tubes - monster.party.hat
So now the question is what to build? I like the Super Fly, to be honest and maybe this will be the one to build.
Well, I have been talking about a tiny 4 ohm speaker, but I totally forgot that I can use my Marshall's Valvestate 8080 speaker as well.
This is a 12'' 8 ohm Eminence speaker. Basically, I could use the sub-mini amp as a head for the Marshall's speaker, I guess.
In this case, would it be better class A or AB?
I've read somewhere that class AB delivers more power than class A (3x more).
But isn't the difference only in the time the tubes conduct? So in class A there is only one tube, so it conducts 100% of the time, whereas in class AB each tube conducts for ~50% of the time.
But this doesn't mean that more power is delivered to the speaker, right? Or am I wrong?
Best regards,
Pedro
Just a silly question. I have many power supplies at home savaged from iMacs and MacBooks . Are their transformers of any use?
The largest transformer converts mains (240V) to 5V and 12V. For an 8 ohm speaker, that would imply a primary resistance of ~19kohms. But what about the bandwidth of these transformers. Would they cover the range I need?
Best regards,
Pedro
The largest transformer converts mains (240V) to 5V and 12V. For an 8 ohm speaker, that would imply a primary resistance of ~19kohms. But what about the bandwidth of these transformers. Would they cover the range I need?
Best regards,
Pedro
Even if there are transformers in them, they are made for high frequency switching. They will not work in this case.
Class AB normally produces more signal when you can use higher plate voltages, than in pure class A, and you go deeper into class B, where only one of the tubes is conducting. Therefore you need the right transformer and a high B+. The subminiature tubes, however, have a low plate voltage limitation, around 300V, which does not help.
Class AB normally produces more signal when you can use higher plate voltages, than in pure class A, and you go deeper into class B, where only one of the tubes is conducting. Therefore you need the right transformer and a high B+. The subminiature tubes, however, have a low plate voltage limitation, around 300V, which does not help.
Hi Thomas,
So, in subminiature tubes, does it make more sense to use class AB instead of class A ?
I am thinking of building the superfly but there are 2 versions, as you know, class A and class AB.
I understood that if I want to use the amp with my little 4ohm speaker, I would have to go with the class AB. But if I connect the amp to my 12'' Eminence, which one is better?
From my point of view, class A makes sense in high fidelity amplifiers. For guitar amplifiers class AB or even B should be good. No one cares of having more distortion.
Cheers,
Pedro
So, in subminiature tubes, does it make more sense to use class AB instead of class A ?
I am thinking of building the superfly but there are 2 versions, as you know, class A and class AB.
I understood that if I want to use the amp with my little 4ohm speaker, I would have to go with the class AB. But if I connect the amp to my 12'' Eminence, which one is better?
From my point of view, class A makes sense in high fidelity amplifiers. For guitar amplifiers class AB or even B should be good. No one cares of having more distortion.
Cheers,
Pedro
The subminature tubes you want to use as well as the speaker will have you driving the amp hard enough to be heard that the sound will always be distorted. Class AB or B will make you the most power. Without a inverter stage you will only be capable of running in class A. This could drive your 12" although it will not matter much if you use A or AB. With an inverter stage you can decide if you want A or AB, with a Firefly type of design with a self split output you can only run A. It will only cost you a small amount for another tube and associated parts. Mind you, if going to miniature tubes is already out of the budget then adding another stage may be a bridge too far.
Printer2 is right. You need the inverter to be able to run it in class AB. And you need a higher voltage, than you would have in class A to squeeze more power out of it.
The thing with the speaker has more to do with the transformer and the impedance of the primary than the speaker itself. Half the resistance will result in half the impedance. The impedance is chosen to obtain more power out of the amplifier. If you change the impedance, you change the load line and will have to change the bias point. Too hot and yout tubes will melt. The best case scenario considers a load line almost tangential to the max. dissipation line. For the 6N16B, at 200V, this is higher than 20k. Take a look at merlin's page:
The Valve Wizard -Push-Pull
and then take a look at the 6N16B datasheet.
The thing with the speaker has more to do with the transformer and the impedance of the primary than the speaker itself. Half the resistance will result in half the impedance. The impedance is chosen to obtain more power out of the amplifier. If you change the impedance, you change the load line and will have to change the bias point. Too hot and yout tubes will melt. The best case scenario considers a load line almost tangential to the max. dissipation line. For the 6N16B, at 200V, this is higher than 20k. Take a look at merlin's page:
The Valve Wizard -Push-Pull
and then take a look at the 6N16B datasheet.
Hi,
I am sorry for going back to this, but I promise this is the last time I pose questions regarding transformers.
When looking at the transformers, I've noticed that the monacor has, actually,the following taps in the primary:
- 10/5/2.5/1.25/0.625 W
and the secondary:
- 4,8,16 ohm
https://www.monacor.com/products/pa...accessories/audio-transformers/tr-1005/?r=pdf
If this one is not really suitable, I will go with the Visaton.
This is all about cost. The Visaton costs twice as much as the Monacor.
Monacor costs £13 on eBay and the Visaton £25.
Cheers,
Pedro