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Old 25th October 2017, 06:10 AM   #101
PRR is offline PRR  United States
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Originally Posted by Nelson Pass View Post
Hello Kitty. Catchy name. Hello Kitty amplifier....
Done, done, and done to death.

http://craziestgadgets.com/wp-conten...-ipod-dock.jpg
HELLO KITTY lunchbox amplifier | Dendera Bloodbath
https://cdn.instructables.com/FHO/PB...9.RECT2100.jpg
https://i.pinimg.com/originals/44/8c...c61a294db9.jpg
https://www.savingadvice.com/images/...fender-amp.jpg
https://www.riflegear.com/blogimages...KittyParts.jpg
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Old 25th October 2017, 06:18 AM   #102
PRR is offline PRR  United States
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Originally Posted by Ralph G View Post
......Common Mode Choke? Run it balanced. .......
Works fine. Was the core of a very old (Brooks? Bogen?) hi-fi tube amp which pushed the finals into grid current. The driver was two twin-triodes as cathode followers into a 2-coil (CT) choke, to the power tube grids. Only one final grid at a time took grid current, and this coupled all the oomph from four triodes to the one grid sucking.

Disadvantage is you need balanced drive and floating load. Speakers float naturally, and many of you have balanced sources.

In the mofo case, a possible advantage is that the two outputs will be very nearly the same DC level, and you can lose the enormous output cap. (Even if one MOSFET fails, the resulting ~~1V will not smoke any decent woofer.)
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Old 25th October 2017, 06:53 AM   #103
ammel68 is offline ammel68  United States
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Originally Posted by prasi View Post
Continuing, here is the revised layout that follows UMS guidelines (80 mm x 40mm mounting holes and Mosfet mounting at 15mm away from mounting hole.) Also included cap pitch options for C1.

regards
Prasi
Nice work Prasi. Thank you for yet another great layout and for clarifying what "UMS guidelines" are.

Now...let's get those input terminals spaced at 5mm apart like they should be instead of 2.5mm.
You should know that farther apart LS is better and easier for most DIY folks to solder.
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Old 25th October 2017, 07:08 AM   #104
Ralph G is offline Ralph G  Netherlands
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Originally Posted by PRR View Post
Works fine. Was the core of a very old (Brooks? Bogen?) hi-fi tube amp which pushed the finals into grid current. The driver was two twin-triodes as cathode followers into a 2-coil (CT) choke, to the power tube grids. Only one final grid at a time took grid current, and this coupled all the oomph from four triodes to the one grid sucking.

Disadvantage is you need balanced drive and floating load. Speakers float naturally, and many of you have balanced sources.

In the mofo case, a possible advantage is that the two outputs will be very nearly the same DC level, and you can lose the enormous output cap. (Even if one MOSFET fails, the resulting ~~1V will not smoke any decent woofer.)
I am already collecting parts for a F6, so an input transformer should be here soon (Monacor LTR110). This transformer can be used for balancing two MoFo amps.

In my SIM I already took the caps out. Using a second Mosfet for balancing is cheaper than these caps.

The only thing I'm not so certain: can a 5 euro/dollar 68mH/3A common mode toroid really be used in stead of a 25 euro/dollar Hammond. Sounds too good to be true.
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Old 25th October 2017, 07:15 AM   #105
Ralph G is offline Ralph G  Netherlands
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Originally Posted by aspringv View Post
OK, well, crazy idea ahead that will demonstrate my ignorance no doubt

What if I use a dual secondary (or primary i suppose) power torroid for the inductor. I wire the secondaries in parallel, except reversing the direction of the coil. Ie the magnetic flux from each secondary is cancelling the other. Thus we get a large value iron core inductor from a power torroid that doesn't saturate with a DC current running through it.

(says the guy with plenty of spare transformers, but no air gap inductors)
I think you are cancelling out the AC part too. So no inductance. Not sure. But if I understand Iron Pumpkin it should be possible to use the powerline for current compensation (the DC voltage going to the amp part).
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Old 25th October 2017, 07:37 AM   #106
jostwid is offline jostwid  Switzerland
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Originally Posted by Nelson Pass View Post
Hmmmmm......

Hello Kitty. Catchy name. Hello Kitty amplifier....
Hello

For a lunchbox amp it is a bit heavy (~ 70 pounds)

It got its name because it is made entirely of parts that came together over years... Even the IXYS i had bought years ago

wooden frame made in 2003
Cast iron foot from an old machine
Heatsinks from a Sudgen A21a (gift from a friend who found them in the garbage)
Chokes from old projects
Power supplies from dead laptops

It has a number of advantages

difficult for thieves to run away with it
~ 99% recyclable
~ 98% reusable
excellent investment
even sounds decent
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Old 25th October 2017, 08:04 AM   #107
jostwid is offline jostwid  Switzerland
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Originally Posted by Circlomanen View Post
What is your impression from the IRLP3034 in that circuit?

Regards,
Johannes
Hello Johannes
Unfortunately i lack the reference point to answer your question, because i use different parts in different topologies.
And in addition both the topologies and the parts have different driving requirements
and my speakers are on the extremes as well (DF requirements)
And i am no good in multifactorial analysis...

In order to make good use of a MoFo i now need a good preamp with
30 x voltage gain, that can swing 12V with low distortion and has a low output impedance
Something around autoformers....
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Old 25th October 2017, 08:40 AM   #108
aspringv is online now aspringv  Australia
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Originally Posted by Ralph G View Post
I think you are cancelling out the AC part too. So no inductance. Not sure. But if I understand Iron Pumpkin it should be possible to use the powerline for current compensation (the DC voltage going to the amp part).
I'm going to have to do some more reading I'd say! I was channeling the zen variations 7 article choke loading, and just kinda wondered.

Following that logic though, it'd be easy enough to do a balanced version in the zv7 choke fashion.
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Old 25th October 2017, 08:50 AM   #109
Ralph G is offline Ralph G  Netherlands
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Originally Posted by aspringv View Post
I'm going to have to do some more reading I'd say! I was channeling the zen variations 7 article choke loading, and just kinda wondered.

Following that logic though, it'd be easy enough to do a balanced version in the zv7 choke fashion.
Yep. That was my idea too. I always like the Son of Zen concept, but the lack of efficiency scared me out of this. The ZV7-T variant is better, but it needs a huge transformer to operate nice at lower frequencies.

A ZV7-TMF (so Son of a choke loaded MoFo....) would work with a way smaller choke, because the impedance it sees is way lower.
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Old 25th October 2017, 09:20 AM   #110
aspringv is online now aspringv  Australia
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Originally Posted by Ralph G View Post
Yep. That was my idea too. I always like the Son of Zen concept, but the lack of efficiency scared me out of this. The ZV7-T variant is better, but it needs a huge transformer to operate nice at lower frequencies.

A ZV7-TMF (so Son of a choke loaded MoFo....) would work with a way smaller choke, because the impedance it sees is way lower.
I bought a few 650VA toroids with 30V secondaries at a knock down price a while back, and had always intended to try a ZV-7T with them. One day. :/ Assuming I finish all the other amps I have lined up.

Last edited by aspringv; 25th October 2017 at 09:31 AM.
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