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Switchinglow Project
Switchinglow Project
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Old 7th December 2016, 04:19 PM   #1
Marco Rampin is offline Marco Rampin  Italy
diyAudio Member
Join Date: Feb 2016
Location: Italy
Default Switchinglow Project

Hello to every lucky lover of silicon,
I mean in the form of a glass envelope
surrounding metal electrodes dipped in vacuum.

As I've already posted in the Amplifiers Class-D section of this forum,
I come in peace from the Switching Tubes Valley.

I hope not to hurt too much the fine acoustic sensibility
of all-analog-audio-path followers,
but all you know tubes can work also in on/off states,
not only in linear region.

My project uses tubes to apply the electric energy
provided by the power supply to the load,
and thus it is still a tube amp,
even if not linear but Class-D.

After exhibiting at the European Maker Faire and at the Burning Amp 2016,
I post the Switchinglow Project also here
for all the brave DIYers that would like to catch
the challenge of exploring what it seems to be a New World.

In previous years I've developed a reliable method
to use tubes as switching power devices in class-D
amp circuits and I've called this method "AmpDiVa technology"
where AmpDiVa means Amplificatori Digitali Valvolari,
or Digital Tubes Amplifiers.

The AmpDiVa tech uses:

- vacuum tubes as switching power devices in the arms
of a full or half H bridge Class-D circuit

- tubes can be connected in parallel on each arm
in order to achieve higher output current, as in OTL

- the tubes on each arm are switched by a
Floating Grid Driver circuit that applies,
between grids and cathodes,
negative pulses to obtain the off state of the tube
positive pulses to push the tube in an high conduction state,
according to a PWM scheme provided by a Pulse Width Modulator.

Positive grid polarization seems to be not allowed by the data sheets
of common tubes for consumer applications.
Nevertheless it has considered up to a certain point
of the history of the electronic science.

- Signal Integrity methods are used to timing
the tubes in each arm of the bridge
(this is not mandatory, it's a funny option)

The Switchinglow Project is an evaluation module
proposed to the DIYers that would like to explore
the AmpDiVa method starting from a reliable, affordable
and user friendly platform.

Hereunder is the block diagram (with ECC99 double triodes
drawn as single triodes for easyness as they are
all connected in parallel)
while further readings and info can be found
in my web pages www.switchinglow.com

As I always tell, this is at the opposite side of the long long time
studied and designed linear circuitry,
but in every case it's a real tube amplifier !

So enjoy it and
don't hesitate to ask for any questions !

Marco Rampin

Switchinglow Project
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Old 16th December 2016, 06:05 PM   #2
chinegpl is offline chinegpl
diyAudio Member
Join Date: Dec 2016
Default Hi Marco

About your kit, what are the parts that you can provide?
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Old 19th December 2016, 09:23 AM   #3
Marco Rampin is offline Marco Rampin  Italy
diyAudio Member
Join Date: Feb 2016
Location: Italy
Hi, thank you for your question.

The kit I can provide contains:
- PCBs for the power half H bridge
- all the components to assembly, including 6x 3300uF low ESR el-caps,
ceramic tube sockets with gold pins
and also 8x new ECC99 JJ Electronics
- a breadboard PCB with components to assembly a basic
EMI output filter
- two Floating Grid Drivers already assembled and tested (as they are made in SMD tech)
with two custom 115/230Vac toroidal transformers to supply them and the tube heaters
- one analog input type AD pulse width modulator (also made in SMD tech)
- assembly and instruction manual, only in english for now

You have to provide a 5Vdc 100mA to supply the PWM and a split power supply between +/-12Vdc to +/-90Vdc 1..2A to supply the power bridge.

I can also provide all the above listed parts one by one if somebody needs only some of them.

Please only consider I'm not an electronic board manufacturer, so I can provide only limited quantities to DIYers really interested in this challenging circuit.
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Old 20th December 2016, 02:06 AM   #4
soekris is offline soekris  Denmark
diyAudio Member
Join Date: Jun 2009
Location: Korsør, Denmark
Switchinglow Project
Is it already April 1st ?
Søren - www.soekris.dk
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Old 20th December 2016, 08:47 AM   #5
Marco Rampin is offline Marco Rampin  Italy
diyAudio Member
Join Date: Feb 2016
Location: Italy
No, no....
unfortunately we are still in winter
in this part of Europe...

The Switchinglow Project EVM has been shown
running at the mid november Burning Amp festival
coupled to some Fritz's speakers and also at the Gran Gala' dell'Alta
Fedelta' in Milan (in this case I had only a "static" booth
so I've shown only the working signals with the oscilloscope).
And in mid october I had an AmpDiVa amp prototype
playing at full volume during the European Maker Faire in Rome.
The AmpDiVa are complete amps made with the same Switchinglow circuit,
but they are targetted for the hi-end, not for DIY.

So, a Class-D tube amp can be really designed and built.
Of course, as I've already wrote in some other place of this forum,
it is not possible to achieve the same power efficiency of a solid state Class-D amp, but in any case this represent the fourth cornerstone in electronic amp design after linear tubes, linear solid state and switching solid state.
So I believe it could be interesting for DIYers looking for something unusual.
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Old 8th February 2017, 09:05 PM   #6
chinegpl is offline chinegpl
diyAudio Member
Join Date: Dec 2016
I have a friend that should be interested in your kit.
Is there an italian instruction manual included in it ?
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Old 11th February 2017, 04:33 PM   #7
Marco Rampin is offline Marco Rampin  Italy
diyAudio Member
Join Date: Feb 2016
Location: Italy
First of all sorry for the delayed reply to your kind inquiry.
Then sorry also for not having a manual already available in italiano.

The kit is provided with a detailed instruction manual in english
full of pictures.
It should be not so difficult for a guy skilled in electronics
to follow it.

In any case I can offer reasonable support by e-mail, skype, phone or also visiting my workshop to everybody will start to build the kit.
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Old 4th May 2017, 08:50 PM   #8
Oneminde is offline Oneminde  Sweden
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Join Date: Jun 2014
Location: Darkside of the moon.
Its been a quiet thread, but I am interested in the boards and component list / instruction manual. What is the price of this ?

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Old 5th May 2017, 08:39 AM   #9
Marco Rampin is offline Marco Rampin  Italy
diyAudio Member
Join Date: Feb 2016
Location: Italy
Thank you for your inquiry.

You can find all the info you need visiting the www.switchinglow.com home page.
Please click on "How to order" at the bottom of the page and then find there the price for the whole kit or the discounted price list for the parts.
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Old 11th May 2018, 07:29 PM   #10
Mr Mayhem is offline Mr Mayhem
diyAudio Member
Join Date: Nov 2013
I am interested in buying a pair of kits for stereo. Is the kit still available, and can I get it with the new grid driver design which floats the grid during the positive pulses? I don’t see the how to order link or prices on that page, only your email link. I was also wondering how feedback could be used to close the loop on the class d circuit to improve performance, as is typical for semiconductor class d designs. I didn’t see any feedback loop back to a comparator in the docs so I guess your design is open loop (without feedback)?
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