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zig290682 10th June 2009 02:59 PM

VALVOLOZZO triode amp with toroids output me
Hello to all,
iam a new entry to the Forum. My name is Emanuele, i have 26 years and i write from Vicenza (Italy).
Are hi fi enthusiast and I like to design acoustic loudspeakers: I am passionate about hi fi and i like to design acoustic loudspeakers: But I know little electronics to judge the quality of amplifier projects!

My old friend, the engineer Diego Barone has done for me (well a few years ago) all the circuitry for the amplifier VALVOLOZZO modified version.


Has already been opened in the past treadh on this amplifier has been critical of the circuit and the type of output transformers.
My output transformer use a toroidal, a capacitor mkp Sonus Faber 72 microFarad and hammond inductance.
Listen to me seemed good, even in low range, perhaps with a little high 'polished.
My system is:
* Technics direct drive turntable with hand made marble plinth, toneaem Moerch DP 6 cartridge mc Fidelity Research Fr 1 mk III-F retipped by Tolai Roberto with Gyger S
* preamp NAD 1300 with Burson Audio op amp
* CD player NAD 5000 + Audio Alchemy DAC
* speakers Sonus Faber Concertino

I am going to make DIY speakers tower with a wideband 13 cm , woofer eminence delta 12 lf in bass reflex + supertweeter Fostex FT 17 H (94 dB/1w/1m)

I would use (if it is a good choice) the amplifier VALVOLOZZO: I just realize the cabinet.

My question is: how can I improve the circuit in my possession?
This project is considered really good or bad? with your help I will understand if VALVOLOZZO set aside to buy a T-amp kit (hypex
I apologize for my bad English ... expect many answers!

zig290682 10th June 2009 04:23 PM

I have a problem: I can not insert images. who should I contact?

Cal Weldon 10th June 2009 04:24 PM

Go to the bottom of the reply window and hit the browse button. They have to be 100K or less.

zig290682 10th June 2009 07:10 PM

circuit scheme
2 Attachment(s)
circuit scheme...

zig290682 10th June 2009 07:10 PM

power supply
2 Attachment(s)
power supply...

zig290682 10th June 2009 08:26 PM

Each type of comment is welcome, thank Cal Weldon for the help!

Shoog 10th June 2009 08:38 PM

The input stage seems to have a slightly unusual CCS on the top in that it seems to be operating as a constant voltage element - and replacing that with something better might improve the top end clarity and extension (mosfets have high input capacitance ).
Other than that it looks like a well thought out and designed amp. Toroidals in Parafeed amps will far outperform any conventional EI amp. The only thing that can happen is they can ring out at about 50khz. Scoping it up with a signal generator would show any of that up.

The only reason to criticize this circuit is ignorance and prejudice.


Cal Weldon 10th June 2009 09:22 PM

Glad I could help.

revintage 11th June 2009 06:51 AM

Ciao Emanuele,

What are the tube types in your amp?

The CVS on top of the input tube has just been discussed and found interesting as it mimics a anode choke at the same time as it has a fixed voltage. It will probably not compromise your top end. Though I wonder about the 1u cap, resistor and potentiometer from anode to ground, some kind of hum reduction?

revintage 11th June 2009 08:22 AM

Check this one:

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