DIY Voyager power amp Build

[337alant]

Finally got round to starting my build of a pair of monoblock amplifiers based on the Avondale Voyagers
I have been using the NCC200 amplifers for a few years now and also builts some voyager clones by Hacker ( the Hackernap amplifirer).
All of these amps are based on the 1960s RCA power amplifier circuit that NAIM also used in all of their Chrome Bumper amplifiers
Its a tried an tested design that provides an excellent solid state power amplifier that sounds fast clean with high transient performance, the sound can be tailored to your taste particularly by the choice of components with the feedback and input cap having a significant effect on the voicing of the amplifier., NAIM chose solid tantalum capacitors for these caps and that gave their amps that fast clean sound with an upfront presentation, some find their sound initially impressive but fatiguing in the long term, if you use film caps the sound will be a lot smoother and sweeter but can lack the excellent bass impact of the tantalums. My own preference is to use a Military spec Wet tantalum capacitor bye passed with either a 100nf polypropylene or polystyrene capacitor this retains all the speed and dynamics of the solid tant but sweetens the treble and still retains the excellent bass performance but also with a 3 dimensional image.

So for this build the amplifier modules are the excellent Avondale NCC200 amplifiers built using Dale RN60 resistors throughout except for resistors in the signal path which are Audio Note tantalum resistors, matched transistors are used throughout and Capacitors are all high quality Polypropylene, polystyrene, silver Mica and military spec wet tantalum types.
The Power supply is divided into two sections the input & VAS section and the output section which ideally have different needs in a 3 stage power amplifier, some amps just supply a raw supply to all 3 states such as the Naim Nap 90,110,140,160, 180 range which used the same power amplifier bord with different power supply’s, or a regulated supply to all three stages such as the Naim Nap 250 but neither of these is ideal and the fornt end requires a quiet Regulated Constant current supply but the output is ideally supplied with a raw high current delivery supply.
So on this amp the input section has a 42-0-42V x 50va C core transformer, followed by rectification and smoothing from a Cap 6 module using Q-speed 6amp ultra fast Diodes and 6 x 4700uf Rubicon smoothing caps with a 6.8ohm-2W resistor in between to provide ripple reduction, the front end needs a regulated constant current supply so a VBE regulator supply is used

The output section needs an raw unregulated supply to provide high current delivery this provide the speed, dynamics and transient performance so no regulation is used here as this can strangle transient performance. The output is supplied from a 35-0-35V x 500VA C core transformer, with rectification and smoothing supplied again by a Cap6 module using Q Speed 30A rectifiers and 5 x 6800UF Kendiel Capacitors with a 10mh inductor between them.
Speaker protection is supplied by the velleman K4700 modules
Everything is housed in the excellent Modushop all aluminium pesante dissapante cases http://www.modushop.biz/ecommerce/cat079_l2.php?n=1

Hopefully I will get most of this done this work done this week before I have to go back to work but I am still waiting for some parts so ?

basic layout in the case and there is loads of space
IMG_1310 by 337alant, on Flickr

IMG_1309 by 337alant, on Flickr

This where I am up to with the amplifier modules, I am still waiting for all of the transistors and some caps.

I may be being a bit anal here but I have 3 different 100uf / 100v caps to use for the power rail decoupling, by Elna, Panasonic FC and the rubicon ZL all are very good with the Rubicon has the lowest ESR and fits perfectly any preference on which I should use?

IMG_1324 by 337alant, on Flickr

IMG_1325 by 337alant, on Flickr


Will update as I make progress

Alan

[Firebottle]

Wow, attention to detail

Alan

[337alant]

Yes thanks Alan, I have found it makes a difference in the end result and may as well do it as I build that wishing I had done it later

Alan

[337alant]

Made some more progress on the NCC200 boards today and almost populated now but I am short of the heat sinks for the output drivers I had 2 but cant find them anywhere ?, ordered some more from Les

The transistors and Polistyrene caps arrived this morning so measured them all and installed them
Made up the output inductors, 16 turns of transformer wire on a 6mm drill, and 15 Ohm x 2W Kiwame resistor used
The output inductor is the part that Naim omitted ?, this makes the amp stable into all speaker loads, but I guess Naim allways planned on selling hundreds of thousands of meters of speaker cable to compensate good business plan I guess
http://www.hificollective.co.uk/components/kiwame.html

voyager 2 by 337alant, on Flickr

Fitted the output transistors to the VBE boards

Found some Nichicon Fine Gold 100uf x 63V caps for the rail decoupling caps so fitted them as well

voyager 1 by 337alant, on Flickr
Ill have to start doing some case work tomorrow

Alan

[337alant]

No progress yesterday as the mains cable to our house burned out during the night so I had no power all day and my drive way had to been dug up ,
Power back on now but it took them all day

Alan

[CageyH]

Sounds like a complete nightmare.

[dowser]

No progress yesterday as the mains cable to our house burned out during the night so I had no power all day and my drive way had to been dug up ,
Power back on now but it took them all day

Alan

Caused by you Alan?

Nice build

[slate]

Caused by you Alan?

Nice build

First test run of the amp?!

[337alant]

Caused by you Alan?

Nice build

Hi Richard
LOL yes more than likely, that much HIFI gear switched on 24/7 in my house

Alan

[RichB]

Nice bit of work Alan.

You builds are second to none based on what I've seen and heard. This looks to be no exception.