Hello,
This is my first post here. This forum is amazing and I would like to thank you for the great content and hugely supportive community.
After watching numerous videos on subminiature tube amplifiers(mostly from Thomas), I have decided to build one.
Initially, I've watched videos from "Uncle Doug" who is an amazing youtuber and teacher. He was the one who sparked my interest on valve amplifiers.
Thank you Doug !
As first project, I would like to start with lower voltages and small form factor amps. After looking on the web, I discovered the subminiature valves.
This is what I have in mind.I am thinking of replicating either a Fender Champ or a Marshall JCM 800 amplifier (I came across schematics from Thomas on numerous amps including JCM 800s).
With zero experience in this subject, I thought of using the following components:
- 6N16B and 6N17B valves
- Monacor TR-1005 100V Line Transformer MONACOR: TR-1005
- 4'' woofer was taken from a Logitech pc sound system
- Laptop SMPS
- DC-DC boost converter for nixie tubes
I have several questions:
1 - Are the components above ok for these amps?
2 - The speaker that I have is rated 25W and 4 ohm. Will the tiny amp be able to deliver enough power to drive it? Usually I see schematics with 8 ohm speakers, not 4 ohm ones.
3 - To have enough power to drive the speaker, would it suffice a two stage pre-amp, or would I need more stages to increase the gain ?
Thanks in advance.
Best regards,
Pedro
This is my first post here. This forum is amazing and I would like to thank you for the great content and hugely supportive community.
After watching numerous videos on subminiature tube amplifiers(mostly from Thomas), I have decided to build one.
Initially, I've watched videos from "Uncle Doug" who is an amazing youtuber and teacher. He was the one who sparked my interest on valve amplifiers.
Thank you Doug !
As first project, I would like to start with lower voltages and small form factor amps. After looking on the web, I discovered the subminiature valves.
This is what I have in mind.I am thinking of replicating either a Fender Champ or a Marshall JCM 800 amplifier (I came across schematics from Thomas on numerous amps including JCM 800s).
With zero experience in this subject, I thought of using the following components:
- 6N16B and 6N17B valves
- Monacor TR-1005 100V Line Transformer MONACOR: TR-1005
- 4'' woofer was taken from a Logitech pc sound system
- Laptop SMPS
- DC-DC boost converter for nixie tubes
I have several questions:
1 - Are the components above ok for these amps?
2 - The speaker that I have is rated 25W and 4 ohm. Will the tiny amp be able to deliver enough power to drive it? Usually I see schematics with 8 ohm speakers, not 4 ohm ones.
3 - To have enough power to drive the speaker, would it suffice a two stage pre-amp, or would I need more stages to increase the gain ?
Thanks in advance.
Best regards,
Pedro
Thread moved to Instruments and Amps.
Well, you need some experience.
Perhaps start with Marsh/Mojo 5F1 Amp Kit 5 Watt w/ Instruction Manual! | eBay - or something similar, if such a kit even exists elsewhere.
I think the price is a bit steep for what you get, but the first time build experience may be worth it?? Particularly getting hands-on with something that's probably going to work when you turn it on - you'll see what kind of parts go where and with some investigation, eventually learn why they were valid design choices.
I wish I could recommend something a bit more wallet friendly, but a quick search only turned up this listing. Others are there, but major components (the expensive ones...) are missing from those kits and they still want a couple hundred for them.
Perhaps start with Marsh/Mojo 5F1 Amp Kit 5 Watt w/ Instruction Manual! | eBay - or something similar, if such a kit even exists elsewhere.
I think the price is a bit steep for what you get, but the first time build experience may be worth it?? Particularly getting hands-on with something that's probably going to work when you turn it on - you'll see what kind of parts go where and with some investigation, eventually learn why they were valid design choices.
I wish I could recommend something a bit more wallet friendly, but a quick search only turned up this listing. Others are there, but major components (the expensive ones...) are missing from those kits and they still want a couple hundred for them.
Hi,
Thanks for your reply.
The kit you've suggested is very expensive for me.
With the parts I was suggesting, I would be spending less than £80.
I think the fender champ is super simple. It has only 2 tubes and less than 30 components. Please remember that I already have the speaker and I am only building the amplifier's head.
Cheers,
Pedro
Thanks for your reply.
The kit you've suggested is very expensive for me.
With the parts I was suggesting, I would be spending less than £80.
I think the fender champ is super simple. It has only 2 tubes and less than 30 components. Please remember that I already have the speaker and I am only building the amplifier's head.
Cheers,
Pedro
I think the Monacor TR-1005 100 V line transformer isn't a suitable output transformer to be conform with your idea and tubes. It's got a single, non-tapped primary winding that transforms to an imedance of 1000 ohms, has no air gap etc. Better look for other line transformers with a CT primary and build a PP amplifier with these small tubes. The Omnitronic ELA-T5 and the Visaton TR10.16 for example feature center tapped primaries that transform to 16 kohms. Both are cheap also.
Best regards!
Best regards!
Somewhere in this forum, if you use the search feature, there is a thread in the 100 buck amp challenge thread, where the member "Wavebourn" shows his development of a guitar amplifier based on Russian Subminiatures.
If I recall correctly he used 6N21B and 6N16B, I forget the output stage valve.
So this would probably be a very good point to start at.
It may well be that the 6N21B has just a little too much gain, and perhaps 6N17B would provide enough gain.
Plenty of room to make the design your own, optimised for your needs.
I'll be interested in this thread, since I have loads of 6N16B,17B and 21B plus a lot of small output tubes - it's just another project I havent yet started!
Good luck!
If I recall correctly he used 6N21B and 6N16B, I forget the output stage valve.
So this would probably be a very good point to start at.
It may well be that the 6N21B has just a little too much gain, and perhaps 6N17B would provide enough gain.
Plenty of room to make the design your own, optimised for your needs.
I'll be interested in this thread, since I have loads of 6N16B,17B and 21B plus a lot of small output tubes - it's just another project I havent yet started!
Good luck!
Thanks for your comments.
What do you think about these?
100V Line Transformer Converting Line Signal To 8/16 Ohm With Tapping 5021196033387 | eBay
Eagle 100V Line Transformer With 2.5, 5, 10W Tapings 5021196037095 | eBay
100V Line Transformer Converting Line Signal To 8/16 Ohm With Tapings 2,4,8 W 5021196033370 | eBay
Cheers,
Pedro
Thanks for your reply.
Well, Thomas Hafemanm says that Line transformers are good enough for low power guitar amplifiers.
He has done many different amplifiers. Please check on YouTube. They are really awesome.
Battery Powered Tube Amplifier : 4 Steps (with Pictures) - Instructables
Cheers,
Pedro
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Thanks for your reply and kind words. I will try to keep this thread active.
I will check the thread you've suggested.
Cheers,
Pedro
Hi,
the tubes will work, they have enough gain and the 6N16B can be used for the output stage.
The amp you listed has a push-pull output stage, so it works with the line transformer. The transformer needs to have low power taps (1.25, 0.625) to achieve the desired impedance. You want something around 20k with the 6N16B in push-pull.
Since a transformer multiplies the voltage by a ratio using a speaker with half the resistance (4 ohms) will result in only half the impedance and all your load lines will be off. I would look for an 8 ohm or 16 ohm speaker.
The SMPS is a diffiult approach. It can be very noise if the filtering is not OK. Nixie tubes are not used for sound, so their SMPS do not need to be quiet. They could work, but you will have to test it.
My suggestion would be to start with a tube amplifier with a transformer. You can build something like the champ for way less than what is asked for that kit if you buy the parts separately. The hundred buck thread has a lot of amps that achieve that by using cheaper tubes and line transformers.
If you want something with a SMPS, small, that uses lower voltages try the superfly from frequency central. It uses a 555 SMPS that is easy to build, it has already a layout that fits in a pedal enclosure. Plus, it runs the output stage in self-split push-pull, where you can use the line transformer(10W with 0.625W tap).
"Superfly" - submini tube version of Doug H's Firefly
There are at least 7 different layouts on this thread, you just need to go looking from page to page and use the one that suits you better. There are more builds that use the russian tubes you suggested. It is also powered with a 12v power supply.
Cheers,
Thomas
the tubes will work, they have enough gain and the 6N16B can be used for the output stage.
The amp you listed has a push-pull output stage, so it works with the line transformer. The transformer needs to have low power taps (1.25, 0.625) to achieve the desired impedance. You want something around 20k with the 6N16B in push-pull.
Since a transformer multiplies the voltage by a ratio using a speaker with half the resistance (4 ohms) will result in only half the impedance and all your load lines will be off. I would look for an 8 ohm or 16 ohm speaker.
The SMPS is a diffiult approach. It can be very noise if the filtering is not OK. Nixie tubes are not used for sound, so their SMPS do not need to be quiet. They could work, but you will have to test it.
My suggestion would be to start with a tube amplifier with a transformer. You can build something like the champ for way less than what is asked for that kit if you buy the parts separately. The hundred buck thread has a lot of amps that achieve that by using cheaper tubes and line transformers.
If you want something with a SMPS, small, that uses lower voltages try the superfly from frequency central. It uses a 555 SMPS that is easy to build, it has already a layout that fits in a pedal enclosure. Plus, it runs the output stage in self-split push-pull, where you can use the line transformer(10W with 0.625W tap).
"Superfly" - submini tube version of Doug H's Firefly
There are at least 7 different layouts on this thread, you just need to go looking from page to page and use the one that suits you better. There are more builds that use the russian tubes you suggested. It is also powered with a 12v power supply.
Cheers,
Thomas
Hi Thomas,
Thanks a lot for your reply and for the content you put on the internet on this subject.
The Nixie tube power supply I was referring to, is this one:
https://www.ledsales.com.au/pdf/555_kit.pdf
But you are right, switching power supplies are noisy and I would have 2 of them, one that is a laptop power brick and the other to step-up that voltage to 100V for the anode,
My initial idea was to use lipo batteries that I have at home, with a charger module. Anyway I would have to have some kind of boost converter to step up to 100V or more.
To maintain the amp small, the lipo cells would be inside the speaker cab, which is a small thing as well.
This way, I wouldn't need a laptop SMPS. Just a charger and the amp would run out of batteries.
Nevertheless the Nixie tube power supply is, as well, a SMPS. :-(
Maybe I can squeeze a transformer inside the little cab.
Cheers,
Pedro
Thanks a lot for your reply and for the content you put on the internet on this subject.
The Nixie tube power supply I was referring to, is this one:
https://www.ledsales.com.au/pdf/555_kit.pdf
But you are right, switching power supplies are noisy and I would have 2 of them, one that is a laptop power brick and the other to step-up that voltage to 100V for the anode,
My initial idea was to use lipo batteries that I have at home, with a charger module. Anyway I would have to have some kind of boost converter to step up to 100V or more.
To maintain the amp small, the lipo cells would be inside the speaker cab, which is a small thing as well.
This way, I wouldn't need a laptop SMPS. Just a charger and the amp would run out of batteries.
Nevertheless the Nixie tube power supply is, as well, a SMPS. :-(
Maybe I can squeeze a transformer inside the little cab.
Cheers,
Pedro
Goes to 11
, so it goes louder than mine that goes to 10. (This is Spinal Tap)Amp. goes to 11 (This is Spinal Tap) - YouTube
Yes, distortion is a must !
Cheers,
Pedro
A line transformer with a lower wattage tap might do you better.
100V Line Transformer Converting Line Signal To 8/16 Ohm with Tapings 1,2,4 W 5021196033363 | eBay
This one has a 1W tap which will help. I see no output tube in your lineup. Especially using a line transformer you want something more suited to drive it. I built an amp with a line transformer back in 2010. Have a pair of 12AQ5's as output tubes.
I think maybe you should do a little more looking around to see what others have done. Also you can get a voltage booster built in China that will give your high voltage. Think if you include 390V in a search you should find it. You should determine how you want to use this amp. Is it for portable use or for bedroom? What is the size of cabinet? These kind of details.
100V Line Transformer Converting Line Signal To 8/16 Ohm with Tapings 1,2,4 W 5021196033363 | eBay
This one has a 1W tap which will help. I see no output tube in your lineup. Especially using a line transformer you want something more suited to drive it. I built an amp with a line transformer back in 2010. Have a pair of 12AQ5's as output tubes.
I think maybe you should do a little more looking around to see what others have done. Also you can get a voltage booster built in China that will give your high voltage. Think if you include 390V in a search you should find it. You should determine how you want to use this amp. Is it for portable use or for bedroom? What is the size of cabinet? These kind of details.
Hi,
Thanks for the reply.
The output tube should be 2 6N16B in class AB.
Cheers,
Pedro
I would rather not, unless it has a very low wattage tap.
If you use 4 ohms on the 8 ohm tap it will give you only half the impedance.
5k in this case, which is not what you want for the subminis you suggested. The mismatch will result in a lower output.
Ideally you would have 20k when using the 6N16B in push-pull. This would mean a 16 ohms speaker on the 8 ohm tap.
But you can use 2 speakers in series, so you would have 8 ohms and 10k.
Before you buy a transformer also check the available wattage or impedance ratings. There are some with weird steps, like 1W,3W,6W,10W, where the number of windings keep changing, and are not good for a Push-pull transformer.
Another possibility, for a Single-ended transformer is to buy a transformer where you can remove the core and rearrange the plates, so that they have the required gap. Keep in mind that this is not easy, because most of those line transformers have welded plates. The resulting transformer will probably have less inductance than desired, because the core will be too small, but will work.
If you use 4 ohms on the 8 ohm tap it will give you only half the impedance.
5k in this case, which is not what you want for the subminis you suggested. The mismatch will result in a lower output.
Ideally you would have 20k when using the 6N16B in push-pull. This would mean a 16 ohms speaker on the 8 ohm tap.
But you can use 2 speakers in series, so you would have 8 ohms and 10k.
Before you buy a transformer also check the available wattage or impedance ratings. There are some with weird steps, like 1W,3W,6W,10W, where the number of windings keep changing, and are not good for a Push-pull transformer.
Another possibility, for a Single-ended transformer is to buy a transformer where you can remove the core and rearrange the plates, so that they have the required gap. Keep in mind that this is not easy, because most of those line transformers have welded plates. The resulting transformer will probably have less inductance than desired, because the core will be too small, but will work.