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My New Class A Amplifier - Make in India

magma

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#1
Hi guys

i just received my new amplifier last week
Sharing some thoughts and pics about the same since its a made in india product that makes me proud to own
designer and builder is an ex forum member "cranky" - in Kolkatta

Below is the power amp that arrived last week




heres the primary bank before the 1st floor was installed


heres the booster bank with the gain stages and soft starts and relays


maybe a part of the amp boards showing the caddocks that require heatsinking as well and an ingenious "heat pipe" along the spreader for even heat distribution between all sinks






Some pics show the primary capacitor bank that are cornel dublier ( black ones ) laid out on the floor of the amp,other pics show the 1st floor with the Booster cap Bank ( orange ones )

Initial listening tests have me over the moon.In pure mode I have probably not owned a more resolving and tonally correct amplifier. The amp was designed to match my relatively low sensitivity ATC stand mounts and the designer has done his job well with the amp disciplining the speaker nicely almost with a whip in one hand .Simply put it is probably the best amplifier I have had in my setup yet .I am happy

All PCBs including the amp boards , gain stages etc were custom ordered from a chinese vendor except for the booster cap bank which was made here, components have been imported from farnell including all CADDOCK resistors.

The chasis, transformer and primary capacitor bank were reused from my last build- however the rest is all new including the amp design,gain stage boards soft start speaker protection relays etc

Following are the specs and the one performance shot taken. Noise level is below -110dB, only 2nd and 3rd harmonic rest under noise floor. This is at 4W output (-18dBfs). 1W performance is significantly better,
But usually testing is done at 4W as its the maximum the designer has had to use with almost all speakers he has access to.



Note the total absence of higher order harmonics and the noise floor below -110dB. The calculated THD would be about 0.003% at this output level, and would remain below 0.1% to maximum output


The specs are
55w/8ohm, 110w/4 and 220/2 @ Pure Class A operation (8ohms)
Current limited at 60 amperes for the output and without limiters at 120A
Output protected against DC and overload.
Total amplifier gain 30dB (21db power amp + 9db gain stage)
Input impedance 47k
Capacitor bank (original+ boosted)= 420,000 uF
Biased at 1.9 amps/channel
Continuous power consumption: 400Watts
Heatsink temp above ambient at this bias level 24 degrees
(in a typical ac room they will run at 50degree C and in a non ac open ventilated room expect close to 60 degree on the sink which is actually lower than what many other class A amp heatsinks run at )

Weight : 68 kgs
Size : 19W and 24D

The power amp also includes a discrete jfet preamplifier circuit to enhance gain for a total of 30dB so that it can be driven from low-output sources like a pro audio soundcard or direct from DAC output - if DAC has volume control. This extra gain stage ckt sound signature has been tweaked for a midrange bump with 2nd and 3rd harmonic distortions to imitate tubes. The ckt has two boards, one for each channel with an independent transformer and power supply bank

THIS Preamp gain stage is also featured with a bypass making it possible to run the power amp in PURE mode if you do not require the GAIN or prefer the tone without the gain stage)

This pre gain stage was purely my idea since I wanted to be sure that a low output source could directly drive the power amp and may or may not actually be how the designer would normally prefer


its a pity i am constrained by my room/bathroom
i am sure this amp would be lovely in a large room

The amp has been heard by some FMs in kolkatta
im sure they have their own opinions as well

pratim and Asit da has also heard and appreciated an amp i think from the house of the same designer
 
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keith_correa

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#5
I LOVE it. The more complex the better, in my book!! Congratulations to the designer!

1 Q: Why were the PCB's ordered from China? Didn't find anyone good enough here?
 

rikhav

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#6
I had an opportunity to listen to the amp. Thanks Ali for that

Even without proper matching cables, no proper speaker setup it was sounding fantatsic

They dynamics were super good and the amp had super control on the speakers
Had all the traits of super class a amp

I prefered it playing without pre
 

skdas

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#8
Congratulation!
Is you room set up and speaker positioning are over?
What is your impression now ?
 

magma

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#10
sk

Hi guys

Initial listening tests have me over the moon.In pure mode I have probably not owned a more resolving and tonally correct amplifier. The amp was designed to match my relatively low sensitivity ATC stand mounts and the designer has done his job well with the amp disciplining the speaker nicely almost with a whip in one hand .Simply put it is probably the best amplifier I have had in my setup yet .I am happy
currently
i am running the power amp directly off the JULI

so no B1 buffer in the path

simply one interconnect that connects the JULI to the power amp
Volume control is thru JULIs pro mixer
and in pure mode im at 90% - ( so basically almost no bit loss)

will try with gain stage connected next week

this was a change after Joshua and riks visited me
I think it was a change for the better
Im hoping to complete the speaker setup this week

but inital impression is as posted in my first post
the amp reminds me of an accuphase ( unfair comparison and highly bold - but what the hell )
 
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magma

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#13
hey guys
many thanks to all who appreciated !!!

hoping to see good stuff manufactured here

i was keen on supporting a small group of "locals" who i trusted, know enough (and in some cases more ) about amp building as compared to overseas counterparts
Their attention to detail level of professionalism and no compromise attitude bound with their collective knowledge about electronics drew me to them

yes they do take time to deliver
but thats because each build is a custom build
they dont hold inventory and hence the order process for compomnets and cabinets takes some time since it starts from scratch on each order
 

prem

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#15
Hi Magma

Do Cranky and his team plan to have off the shelf products or will they be only making customised stuff? Do they sell under any brand name? Any links to any website or anything?

Some details I guess will be helpful to all:)
 

magma

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#17
Hi Magma

Do Cranky and his team plan to have off the shelf products or will they be only making customised stuff? Do they sell under any brand name? Any links to any website or anything?

Some details I guess will be helpful to all:)
they do have a brand
FNL - first note labs

however this amp could not have their brand written on it
since it borrowed design philosophies from Mr Pass,Erno borbely and JM Plantefeve and was basically something i commissioned them to do

they do have their own designs for a 140rms/channel class AB and a 50 rms class AB which is more what the markets are probably looking for
the 50rms class AB is almost ready for off the shelf production

what i like about them is that cranky is terribly conservative on his specs
and always has measurements to prove his work in realtime
Plus hes one of those measurement freaks who relies pretty much on measured numbers rather than calculated ones


X*3 rms at THD of 0.1% is no where close to x rms at 0.003% THD

for example Mr pass's XA 30 specifies power output of 30rms class A at 0.01% THD
he coulld have very well said
70rms @ 0.1% THD like most other manufacturers
but he chose not to
so when you actually bench measure the XA 30 it measure well above that 30rms

cranky somewhat follows a similar philosophy
 
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prem

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#18
Thanks Magma. Will drop in one of these days to hear the amp after you have set it up
 

himadri

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#19
Congrats Magma
First Pratim and now yours.Cranky's class A amps are replacing serious products.Im sure they will interest a lot of people who are looking for something similar as the imported stuff is hugely expensive.Now will have to get to listen to one of those.
Cheers
 
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