Kei,
Very nice looking amplifier!
Are you using Global Negative Feedback?
How many dB of Global Negative Feedback?
What is the Open Loop / Closed Loop gain difference in dB?
Very nice looking amplifier!
Are you using Global Negative Feedback?
How many dB of Global Negative Feedback?
What is the Open Loop / Closed Loop gain difference in dB?
Thank you. 🙂
Yes, it uses gNFB. These were my measurements. The target was 17dB of NFB.
Open loop = 49.54dB
Closed loop = 33.26dB
NFB = 16.3dB
Not an amp however tube related.
These are pics from a friend of mine that builds a lot with my PCB's.
These are little regulator boards for the heaters of directly heated tubes, he is rather pleased with them.
These are pics from a friend of mine that builds a lot with my PCB's.
These are little regulator boards for the heaters of directly heated tubes, he is rather pleased with them.
Attachments
EL84, ECC83S monoblocks, using readily available and cheap transformers (toroidal mains power, 100v line output transformers)
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whow this is quite busy in those boxes ! Monoblocs are a long-term target on my list. Always nice to see how other people build them. Any more details ? schematics ? links ?
Some unpolished schematics here Imgur: The magic of the Internet
Not the most elegant design by any stretch, it's a compromise as the line transformers don't have exactly equal windings, and less inductance than desired. It's optimised for bass performance over outright output power. 0.1% thd at 1khz measured at 1Watt into 8ohm. About 8W at the onset of clipping.
Not the most elegant design by any stretch, it's a compromise as the line transformers don't have exactly equal windings, and less inductance than desired. It's optimised for bass performance over outright output power. 0.1% thd at 1khz measured at 1Watt into 8ohm. About 8W at the onset of clipping.
whow, so much mechanical design to put all this stuff into such small boxes ! I like the rounded PCB, that serious attention to details !
Hi Guys,
I´d like to share some pics of my new 2A3H SET amp which is a special edition of the Sun Audio Uchida kit (based on a 300B kit). It is dedicated to operate the 2A3H only with its 2.8A heating current. A standard 2A3 can also be operated but it will be slightly overheated (2.6A instead of 2.5A heating current). All details and a report can be found on my blog but it would be much too much content for this thread.
2A3 Maniac strikes back!: Sun Audio Uchida Model SV-2A3H - Special Edition by 2A3 Maniac and Analog Tube Audio
Regards
Carsten (2A3 Maniac)
I´d like to share some pics of my new 2A3H SET amp which is a special edition of the Sun Audio Uchida kit (based on a 300B kit). It is dedicated to operate the 2A3H only with its 2.8A heating current. A standard 2A3 can also be operated but it will be slightly overheated (2.6A instead of 2.5A heating current). All details and a report can be found on my blog but it would be much too much content for this thread.
2A3 Maniac strikes back!: Sun Audio Uchida Model SV-2A3H - Special Edition by 2A3 Maniac and Analog Tube Audio
Regards
Carsten (2A3 Maniac)
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From your website: Consequently the designers of the 2A3H compensated these losses with a higher heater current of 2.8A instead of the 2.5A according to 2A3 standard specification! This means a 2A3H in a standard 2A3 application will be underheated and sooner or later this 2A3H would get damaged.
Are the transformers that tightly specced that it can't offer those 0.3A extra?
Are the transformers that tightly specced that it can't offer those 0.3A extra?
I do not really catch your point here:
If you plug a 2A3H into an amp designed for a standard 2A3, the circuit will only provide 2.5A, even if the 2A3H sucks for more current.
In my amp the circuit is designed to provide the required 2.8A - no issue for the power transformer to provide it.
Ah, ok, clear.
Well, in my amp it will of course not be underheated because it is especially designed and engineered for the 2A3H to provide the required 2.8A heating current.
But if you plug the 2A3H in an usual 2A3 amp as a replacement tube, it will be underheated.
Well, in my amp it will of course not be underheated because it is especially designed and engineered for the 2A3H to provide the required 2.8A heating current.
But if you plug the 2A3H in an usual 2A3 amp as a replacement tube, it will be underheated.
drteming,
What a beautiful amp!
Is that a Damper Diode there to give Slow B+ startup?
(Soft Start?)
What a beautiful amp!
Is that a Damper Diode there to give Slow B+ startup?
(Soft Start?)
