Upgrade F5 to F6

[Full Range]

I thought you may like it. There is absolutely nothing wrong with the sound using a good SS pre but to me the F6 sounds much better with a good tube pre or for that matter any SS amp. I would love to hear the Luminaria preamp with the SIT's to compare. This is with horn speakers, I do not know if there would be as much difference with conventional speakers.

Yes quite right
Horn speakers are a different beast altogether
Get it right and its Nirvana
Little pepper and salt changes is the norm for me

FR

 

[Russellc]

The next review @wdecho

You will all remember on the last occasion my review was the F6 connected to the Nakamichi pre amp

This time the F6 is connected to my one of a kind custom valve pre amp with a twist? - you see its also a DAC with an OEM TDA 1541 chip
Made by Earle Weston in Australia - sb343971 - Home

In a nutshell it is a Tube pre-amplifier running a directly coupled 6SN7 driving an output transformer with a OEM TDA1541 DAC board on one of the 4 selectable inputs.
The pre-amplifier acting as a gain stage and buffer for the DAC.

It runs three RCA inputs, then the digital section with momentary toggle switch and LED's that allow you cycle through USB, Optical, SPDIF and I2S inputs.

Specs on the tube section are

Distortion at full volume > 0.06%.
Frequency response +/- 0.25db 20hz to 50khz.
Signal to noise ratio >90db.
Hum at zero volume 0.15 millivolt.
Output impedance 80 ohms.

OK now that's out of the way I can start on the review
Over a week of burn in and everything is very rock solid and stable

Final biasing checked and steady on 500mv

Listening review of the First Watt F6 ( upgraded from the F5 )
Tube 6SN7 pre-amp ( see specs above )
Source - Cyrus CD8 SE
Connected to the TDA 1541 on the pre via coax cable
Medium - CD
Speakers - Klipsch La Scala ( Modified )
Sensitivity min 104db
Album - Pink Floyd - Dark Side Of The Moon and Test CD compilation
Warm up - 1 hour

General - Not as forceful as the Nakamichi pre but is fuller,
lets just say its the difference between full cream milk and fat free milk

Treble - Is very smooth and has a crisp haunting feel, and high notes still hold in the air for a long time

Mid - Is very exact but a little more meat in the music, with an enveloping feel to it (again it's both exact and full at the same time )

Bass - Surprisingly has remained tight with multi layer bass presentation the inaudible bass vibration is still felt even at low volume, however at a slight loss of extended bass range but still totally nice

And to surmise overall performance
I feel that the amp needed more break-in since the last test and that's what it got, a lot of burn-in time. and its worked its magic

The F6 connected to the tube pre-amp and TDA 1541 DAC is equally exact but more analogue and full cream milk in nature

I also ran my test track CD and was totally immersed in the music

Cheers
FR

What sort of circuitry is allowing for your excellently low output impedance? Is there inFo on this preamp on the web?

Thanks for taking time to try it and report back,

Russellc

 

[tubesguy]

What sort of circuitry is allowing for your excellently low output impedance? Is there inFo on this preamp on the web?

Thanks for taking time to try it and report back,

Russellc

It's the output transformer. You can get whatever output impedance you want based on the step-down ratio, trading off gain, of course.

 

[Full Range]

What sort of circuitry is allowing for your excellently low output impedance? Is there inFo on this preamp on the web?

Thanks for taking time to try it and report back,

Russellc

It's based on this model Russell - sb343971 - Touchstone Preamplifier (Tempest Preamplifier)

It's all hand made including hand wound transformers

FR

 

[Russellc]

It's based on this model Russell - sb343971 - Touchstone Preamplifier (Tempest Preamplifier)

It's all hand made including hand wound transformers

FR

Thanks, I will read the article. May not be done building with tubes after all.

Russellc

 

[Full Range]

I will soon post a report testing the F6 on my turntable and vinyl playback
Should be interesting and expecting something special

FR

 

[Full Range]

On this latest review we are testing the F6 on Vinyl playback

The F6 amp is connected to
Nakamichi CA5 preamp
Turntable is connected to the CA5 phono stage and is a
Garrard 401 with Terminator air bearing tone arm
Stanton EEE cartridge fitted with a Jico, Shibata cut stylus and DIY plinth

Now you have all those details, I can start on the review
Biasing checked again and is still steady on 500mv and everything is still very rock solid and stable

Listening review of the First Watt F6 ( upgraded from the F5 )
Nakamichi CA5
Garrard 401 turntable
Medium - Vinyl record
Speakers - Klipsch La Scala ( Modified )
Sensitivity min 104db
Album - Pink Floyd - Dark Side Of The Moon
Warm up - 1 hour

General - What surprised me the most is the cleanness of the hovering megaphone style voices on the first 60 seconds of Speak To Me/Breathe (track one)

Treble - Is extremely smooth and warm, not as sharp as CD playback but it is more earthy in nature overall. Cant really find a complaint to make

Mid - Vinyl playback produces a sound that is fuller overall, on this vinyl album the voices were cleaner to the point that one could determine what voice was closer and what voice was distant over CD but CD playback was sharper

Bass - Volume was needed to get the bass rocking but it was enveloping but remained tight
A little less multi layer bass presentation was observed but the low tones when volume was added came through like a Mack Truck
A slight loss of extended bass range and inaudible bass vibration but still enjoyable

And to surmise overall performance
The amp is now fully burnt in since the last test
Although this test was analytical in nature I gave the record another spin with my senses in enjoy mode
Depending on what media source you choose and level of quality mixing goes into that media the F6 will surprise you with enjoyment

Cheers
FR

 

[Full Range]

Thought it was about time for an update

Just before Christmas I noticed the slightest of hums in the bass section
The only reason I actually noticed this hum was because I was sitting directly in front of the speaker while choosing a record to play ( as you do ) because it can take some time to decide

Anyway after the holidays, my associate put the amp on his Rigol tester and found a small anomaly

So we decided to rewire the power lines and the earth points in the previous configuration that was on the F5

This fixed the hum issue completely
Please see photos of new redirected wiring

P.S. Still enjoying the F6 immensely
FR

 

[2 picoDumbs]

Looks good.

 

[Full Range]

Looks good.

Thanks Pico

I should also mention that all internal wiring is silver plated OFC copper

FR

 

[2 picoDumbs]

Thanks Pico

I should also mention that all internal wiring is silver plated OFC copper

FR

Did you purchase locally?

 

[Full Range]

Yes the wiring and other I items were locally sourced from Speaker Bug in Brisbane - SpeakerBug

They are the Australian distributors of Jantzen capacitors and that's where I got my parts to build my crossovers

The PCB components for the F6 build were sourced from all over the world

FR

 

[Zen Mod]

where is da bloody air in that amp ?

 

[2 picoDumbs]

Ventilation holes are always a good thing

 

[Full Range]

where is da bloody air in that amp ?

Top cover is ventilated directly above the PCB boards and transistors lads

FR

 

[Zen Mod]

nearly not enough

for proper air circulation , you need both intake and outtake holes

though - those are your caps , xformers and other parts , not mine

you can cook them whichever way you want

 

[Full Range]

nearly not enough

for proper air circulation , you need both intake and outtake holes

though - those are your caps , xformers and other parts , not mine

you can cook them whichever way you want

For you I will add some large holes with my metal hole drill bit @ approx 28/30mm on the base plate
Probably fit two on each side easily but will measure for three each side if comfortable

FR

 

[Zen Mod]

aren't you having original bottom plate ?

 

[Full Range]

No that's how this particular cabinet is built
But as a mechanical engineer I agree with your notation on cross ventilation

It will take me 20 min to do the driling job - easy as buttering toast for me

FR

 

[Zen Mod]

(or just put some spacers between bottom plate and rest of the box , with longer screws ; say that 6-8mm will suffice)