Le Classe A - DIY Jean Hiraga Super 30W Class A Amplifier

[all4music]

hi all,

let me start by thanking few FMs with whom i've interacted over more than a year regarding this build. Georgeo , SaikatBiswas , hifiramr and Sadik - buddy builder [sorry if i missed out somebody]. i haven't met any of them but still they have spent so much time over phone explaining/helping me in my understanding about the amps in general. hats off to spirit of DIY community :clapping:


now about the build. it's been almost 2 years that i decided to build this particular amp. it is very hard to document everything now as there is so much detail to cover. let me attempt it .. [most of the pics/text is from a different forum where my thread is posted - it's just easier post pics there . i'll try to link pics from there, hopefully it should work]

-----------

initially i was interested in building valve amps but looking at complexity and those alien bulbs i decided to stick to solid state amps. at high level, amplifiers per se are simple. dc power supply + amp pcb + heat sinks. simple! while looking for simple Class A amp build i came across Jean Hiraga's amp schema. it is based on an article published in a French magazine "l'Audiophile" by Jean Hiraga. not sure if it ever got commercially produced for general public. but there are few variations of the design out there with outputs of 8W/20W/30W.

it looked pretty simple with very few electronic parts on circuit and i read it needs high capacitance = 6 numbers of 20,000uF capacitors to build power supply. pcb was available on ebay. checked for availability of parts online and everything looked simple. so i'm set! first i procured the amp PCBs from Jim's Audio off ebay.com . i even posted a thread on diy section about the amp.

i kept looking for electronic components required for the amp. this went on for few months. finally, BOM on elements14 was huge. i was planning to buy double quantity of everything for matching purpose.


i finalized the soft start and speaker protection modules- bought them from theaudiocrafts.com
soft start has thermal protection built in, which cuts off the power if the temperature reaches 75 Degree Celsius [pic from portal]

2 units of toroidal transformers for power supply from Torotrans, Pune

since i was finding it difficult to source all the required components, i decided to order the complete kit from Jim's audio which includes supposedly 2% matched output transistors and hard to find driver transistors.

i actually assembled pcb last since i was concerned about my soldering abilities. i was worried that i might destroy the board or components because of heat.

few components soldered onto pcb,

caps:
0.1 F caps! 5 of them in the pic. humble Tata Sky remote for comparison. this was the most difficult thing to source in this entire build probably followed by cabinet build..

puny, 10,000uF ELNA caps against the monster caps!

Power Supply
this particular amp design needs one of the most beefy power supply - i mean really meaty! big not in terms of absolute transformer size or voltage but the amount capacitance required. i'm using little more than 5,00,000 uF capacitance in total per channel. in comparison most other amp designs might use total of 20,000 uF caps. so in total i'm using little over 1 Farad of capacitors for filtering and as reservoir. capacitors were one of the most difficult to source and costliest of the components in this build. online sources for caps were turning out to be very costly. then i started looking for local sources. contacted couple of capacitor manufacturers based in Bangalore. initially none of them werer interested in making/selling to end users. one of them routed me through their dealer in SP Road and the cost of those caps were higher than the online prices! after a month i again contacted one of the manudfacturers - Sarada Capacitors. somehow convinced the prodution manager to make 10 numbers 100,000 uF capacitors for me. but they would not sell it to me directly as they would need a TIN of a registered business entity. my cousin came to my rescue as he has a registered business and i got the caps billed to his firm. so voila, in couple of weeks my caps were ready!

[ignore the 5 caps for each bank, it had to be 4 in each]

later i realized that i made a mistake of ordering 10 numbers of capacitors. as i was planning for mono-block builds i needed either 12 or 8 of these caps so that all 4 rails will have equal caps! so in the end 2 of these monster caps are lying unused. but i had make up for lost capacity hence ordered 28 numbers of 'puny' 10,000uF ELNA caps.this also helps in dividing my CRC smoothing circuit properly and smaller caps after rectifier would not put load on transformer by limiting initial rush.

ELNA [visible in the pic only the ground floor of caps , first floor has been removed from box]

amp board needs input of around +/- 24VDC . there are examples of people building this amp with +/-35VDC too.

transformer rating : 400VA with 20-0-20 secondary.
capacitor rating: Sarada Caps- 100,000uf, 50VDC and ELNA Caps 10,000uF, 60VDC
resistor: Ceramic Wire Wound Resistor rated at 30W

CRC circuit: for each rail of each mono-block, after rectifier:
[2*10,000uF] + [0.25ohms] + [5*10,000uF + 2*100,000uF monsters]

testing power supply for the first time, you can see i'm wearing rubber slippers . probably looking at this contraption you might realize that it is not one of those slick build logs.

circuit includes a IEC filer ->soft start -> transformer -> rectifier -> CRC . output DC Voltage is 28.8VDC

 

[kpsthakur]

Cudo's, saved yourself from the misery of blowing up home fuses....


Sent from my iPhone using Tapatalk Pro

 

[Aanuj]

Wow that's a lot of capacitors!!! Won't that stress your power Transformer a little too much? I was going through this topic yesterday on the net and came to know that more capacitance doesn't equate greater performance. The things that do are power rails , transistors (To3,igbt,bjt) then the reserve caps and finally the transformer. If amps transistor part is not robust then the caps do the job but only in case of huge transient response. But then the Transformer too have to be robust and OPTIMUM to fill up the caps quickly. Smaller uf cap bank are always considered better over a larger ones since charge - discharge cycle is quicker and hence better the reaction of the amp to transient shifts. Like older Threshold power amps,huge Transformer,Big rail of Transistor and max of 49-60000uf capacitance per channel. More over caps with 22000uf but 83V will have better dynamic response than a lower V and higher uf capacitor.

Please correct me if I'm wrong.

 

[kpsthakur]

Agree, most of Pass design's end with 8 X 15000uF for dual rail...but most of monster amps can live happily with 8X 10000uF caps for dual rails...only need to ensure that voltage rating is comparatively more...in this case 50V could be sufficient enough


Sent from my iPhone using Tapatalk Pro

 

[all4music]

Cudo's, saved yourself from the misery of blowing up home fuses....

hi Thakur,
sorry didn't get you. why do you think home fuses would blow?

Wow that's a lot of capacitors!!! Won't that stress your power Transformer a little too much? I was going through this topic yesterday on the net and came to know that more capacitance doesn't equate greater performance. The things that do are power rails , transistors (To3,igbt,bjt) then the reserve caps and finally the transformer. If amps transistor part is not robust then the caps do the job but only in case of huge transient response. But then the Transformer too have to be robust and OPTIMUM to fill up the caps quickly. Smaller uf cap bank are always considered better over a larger ones since charge - discharge cycle is quicker and hence better the reaction of the amp to transient shifts. Like older Threshold power amps,huge Transformer,Big rail of Transistor and max of 49-60000uf capacitance per channel. More over caps with 22000uf but 83V will have better dynamic response than a lower V and higher uf capacitor.

Please correct me if I'm wrong.

hi Anuj,
everybody is in the process of learning, for sure i'm. in my limited knowledge:

lot of caps? yes. is that sufficient? probably yes but still little short of original design by Hiraga. as they say power supply forms half of the amp.

in general many smaller caps equivalent to a single huge cap capacity is definitely good. but we can't decide amount of caps is not required unless we try out the same design with various types of power supplies. and there are people who have tried smaller version of this amp running on battery [pure DC] to SMPS [easy/dirty]. also, in my case i've tried to strike a balance by providing smallish caps right after rectifier [before resistor in CRC]. this helps limit the load on transformer. and i think 400VA of transformer is robust enough for the power requirement of this amp board.

coming to voltage ratings: this specific build draws upto 30VDC so 50VDC rating is sufficient and there are designs running tighter tolerances of 35VDC rated caps on diyaudio.

 

[all4music]

Heat Sinks
next part of the build is not that difficult to obtain as such and also this requirement is common across all Class A amps - huge amount of heat dissipation. each output transistor gets it's own chunky bit of heat sink. in reality, a Class A amplifier's is efficiency is in the range of 20-25% . i.e. out of the total power fed to the amp, 70-80% of it wasted as heat hence most of these Class A amps turn out to be monsters.

i stuck to passive cooling[no fan/liquid] by using Aluminium heat sinks for my build. heat sinks were sourced from a Bangalore based manufacturer - Perfect Metals. well i could source the heat sinks easily [in many regions/countries - heat sinks are difficult stuff to source] but prep work for heatsink took the longest time. most of these steps are based on recomendations from Rod Eliiott's site :Elliott Sound Products - The Audio Pages (Main Index)

4 heat sinks. each of them weighs around 2.7kgs with dimensions of width 215mm, length 125mm, depth 75mm . i would need 2 of these for each mono-block. these guys need to get anodized in Black [Black is supposed to be the best colour for radiating heat]. each heat sink is sufficiently sized but the surface area of transistor in cotact with heat sink is very small and generally it recommended to use a spreader which helps in dissipating this heat faster over a larger surface. of couorse spreader has to be a better conductor than Aluminium. next better stuff is Copper. now the Copper stuffs [rods/plates/sheets , you name it] are very easy to find in Bangalore but very difficult to buy! yeah, all these stuffs are abundantly available in SP Road, but all of them are wholesalers. they wouldn't even bother speaking to a guy planning to buy few grams of copper let alone listen to his requirements. but i found one seller - first shop on the left while entering SP Road, who was willing to let me explore and buy required copper plates/strips. though his price were exorbitant but i was ok to pay he let me at least buy them.

for this, 'm using copper plates of thickness 4mm. i need to screw them together so that they are bonded with maximum surface in contact. first, i took the combination to a lathe so that holes can be drilled into Copper and also Aluminium needs to be tapped for a 5mm screw after drilling holes. i had to take them to lathe as i found drilling holes into copper and tapping threads into aluminium are difficult tasks and i wanted to accomplish them with minimal damage to surface area. and surprisingly this took really long time to finish even at lathe - close to 3 hours. each pair of aluminium and copper have 8 holes. 6 for binding copper to aluminum and the rest 2 i'll explain later.

now that the copper spreader is there it's time bolt them on to Aluminium and be done!!? sadly, nope. by doing that we might be doing more harm when compared to mounting transistors on Aluminium. both the surfaces of Aluminium and Copper need to be in very good contact and nope just using thermal compund is not sufficient. hence the laborious process of surface prep begins!!
...

while the Aluminium or Copper look flat, in reality they are not. in order to bond them properly they need to be prepped. there are 2 set of surfaces.

1. Copper plate to Aluminium

for Copper, i used a filer to file the edges of the copper as they were thicker compared to rest of the surface. later, i placed a 150 grit paper over an old lcd screen [acting as a flat surface] of my phone and started rubbing the Cu plate on paper with WD40 as lubricant. once most of the visible irregularities were sanded down, i started with 1500 grit paper. this gave shiny finishing. finally, finished these surfaces with 2000 grit held with the help of straight piece of thermocol .

transistor side surface - other side too has similar treatment,

sandpaper on glass screen, and copper plate is rubbed against it. this is the most time consuming process.

extruded Aluminium surface is far from perfect. Copper plates were drilled with counter sink but aluminium was not. so i used a 150 grit sand paper to level the surface on Alu around the holes. later, i wrapped the Copper plates with 150 grit paper and sanded the Alu block in horizontal motion. this is to ensure Alu assumes the shape of Copper surface and gives better surface bonding - not sure how much of this effort was useful though. all these efforts were spread over at least a month. Copper is bloody hard compared to Aluminium to sand down with hand.

final outcome, far from mirror finish but the best that i could achieve.

2. Transistor to Copper plate

there is difference in the way i've mounted the transistors. it is not bolted on to copper plate , instead it is held tightly against the copper surface with the help of a Aluminium plate bolted on either ends with the help of screws [2 extra holes are utilized here]. transistor sits sandwiched between copper plate and aluminium plate. this is to ensure uniform pressure is applied on transistor die resulting in a firm contact without distressing the transistor jacket [in turn avoids any damage to transistor due to uneven stress].

Aluminium + thermal compound + Copper plate + thermal compound + Kapton tape

transistor mounted!!
[final mounting is without those special audiophile bank of washers ]

i'm using heat transfer compound T-4X supposed one of the best among the compounds [ranked 2nd among all available heat transfer compounds] between these surfaces. and i'm using Kapton tape as electrical insulator between transistor and heat sink.

 

[kpsthakur]

hi Thakur,

sorry didn't get you. why do you think home fuses would blow?

Please don't take me wrong, I appreciated you adding a soft start to the transformer....with this load and capacitance the initial surge is way way high than home fuse can handle....soft start adds that much needed delay required to hold off that effect..

 

[all4music]

Please don't take me wrong, I appreciated you adding a soft start to the transformer....with this load and capacitance the initial surge is way way high than home fuse can handle....soft start adds that much needed delay required to hold off that effect.

nope Sir, i was genuinely interested to know why would fuse blow. i completely understand your concern on the surge. soft start provides a dealy of 2+ seconds and further as i mentioned, i've smaller caps [2X10,000uF] in front of rectifier [as part of CRC] and again smaller banks of caps before the monster reserve caps come into picture. there is no impact on home wiring, not even dimming of any lights [incandescent or otherwise]. but for first power up, even i was concerned and i did make sure that most of the electronics were powered off from mains.

 

[all4music]

now that i had most of the components required with me, i started my hunt for the amp chassis. most of the online options were costly - rather very costly. but they would have given it a real clean look. but i was not ready spend that kind of money especially because i needed two chassis - one each for mono-blocks. one afternoon spotted a sheet metal shop near my brother's place in Mysore, and in a hurry got chassis made. it was very crude and sheet metal was way too thin to take the weight of the amp components.

final placement planning

and in the meantime, i also tried to do a CLC or CRCLC filter. bought 2kgs of 13AWG wire and got wound them into 4 numbers of air core inductance coils. later realised that this wasn't enough as the calculation revealed that the effective inductance was not even 1mH and the simulation on PSUD2 didn't show much of an improvement with these coils. so for now i'm busy planning how to use them as part of home decor

amp pcb has grown tentacles , that is to monitor bias voltage,

first power up with the help of Light Bulb tester and also i connected 4 small 12V indicator bulbs in series to use as power drain from capacitors while working with amp and they also doubled up as Safety Resistors while testing the amp pcb [2 bulbs for each rail]. those papers on wires are for identification - even though i color coded wiring still i was jittery while connecting it for the first time!!

successful power up without blowing anything up or smoke!!

and when i could actually hear some music from my Aiwa test speakers i was literally jumping up and down and probably it was 3AM . music was far from perfect distortion / noise and everything was there but amp was actually working, wow!!!

Music
as described i used Light Bulb tester for powering up the amp pcb. but I when connected speakers, i could hear lot of distortion. after some review i used a better RCA wire from RCA post and took the speaker out negative from 'Star Ground'. later with little more tidying up/tightening of wiring music was almost completely noise free. i didn't hear any hum or noise even when i place my ears close to speakers!! but in the process of adjusting and fine tuning, i managed to destroy one speaker . i had not connected the speaker protection while experimenting. after all the tweaks, music sounds superb especially the sound of tabla and vocals. it's already better than the Swans Monitor and Yamaha sub combo! this is from a single 15 year old Aiwa 2 way bass reflex speakers which if i'm not wrong had more emphasis on bass.

Bias Voltage
now that music was almost set, i started working on setting the correct bias on the amp. suggested Q current for this schema is around ~1.6Amps [any higher, you would need even huge amount of heat sinks!] means voltage of around ~540mV across those tentacles [resistor of 0.33 ohms]. my bias resistors were 33K ohms according Jim's Audio circuit. so i started adding resistors and monitoring the voltages. finally, i managed to bring down the Q current to 1.88Amps! all this while, my heat sinks were performing pretty neat.

Mains Voltage
in all these experiments, i noticed one thing: mains voltage fluctuation has a lot of impact on how amp behaves. and in our area the mains voltage fluctuates from 200VAC - 240+VAC from morning to late night. so my rail voltages vary anywhere from 26VDC to 31VDC ans this has a direct impact on my Q Current [planning to use a voltage stabilizer for the amp]. throughout these experiments, i seldom saw temperature of heat sinks going beyond 54 or 55 Degree Celsius![with the ambient temperature of 25 Degree Celsius] i was quite happy about it. i can place my hand on the heat sink fins for as long as i want even after couple of hours of music play - it is warm but not to the extent that it'll burn fingers.

Kaboom... well almost!
all these checks and adjustments were on a mono pcb and the other though was completely soldered and ready - was never powered up. it only received all the final changes that were done on the firs pcb. this helps in messing both the pcbs for testing. as many would know, desoldering is the most PITA work. i always struggle with it even with a suction pump and solder wick. the solder on the surfeace gets cleared but the solder in pcb holes remains stubborn. now that i was confident that the amp baords are performing well, i replaced the amp pcb with the new one for first power up test. and i powered it up, and immediately i noticed the output resistors glowing red and a very slight noise.. i switched off the power supply as fast as i could. on closer inspection my i realsied that my driver transistors placements were interchanged. i thought they were gone for sure and for replacement transistors i would have to wait for atleast 2 weeks for them to arrive from Jim's Audio if they are available !! luckily measurements showed it was still intact. so quickly interchanged them, made a thorough inspection of the amp board and powered them up. voila!! it worked!!

Drivers
while all this was going on, i was still looking for a better amp cabinet and my full range drivers from Singapore had already arrived. and as per manufacturer recommendations, they were put on a burn in sessions being driven by small Creative speaker amp. input was through my Nexus tab playing Jazz from TuneIn app. and it was initially powered on for couple of hours at a time. later i increased the time to overnight music play - all these at very low volume. suggested burn-in this way was for around 100 hrs. and drivers would take around 400+ hrs to reach their final response it seems!

final run in outside of cabinet - in their own boxes!

for amp cabinet, this time around i wanted to spend sometime in planning it.. so started making few desinges like this [below pics are missing RCA input holes though and one side is completely open, that is just for the view - otherwise both sides will same sized opening!]

final design is slightly different but unable to find those pics.
also, most of my text is composed over the day in a notepad whenever i find time. so you might find it is not coherent and with some grammatical mistakes which creep in while copy pasting.

just a note: please do not keep the heat sinks oriented the way it is in the above pics - in that the transistors are cooking in their own heat. for best radiation of heat, fins should be perpendicular to ground.

 

[all4music]

my initial attempt of cabinet build was a disaster - the metal sheet and workmanship were poor to say the least and since i couldn't spend much time with the fabricator i just grabbed these as is. these boxes couldn't hold the weight of the amp [transformer/heat sinks/caps et al]. so i started looking for other fabricators who could do one off cabinet build for me. most of the engineering works were specialists in building metal structures or wouldn't entertain retail orders. after much searching came across one sheet metal workshop who were willing to make cabinets to my specifications. as mentioned there are options online where you get 'make to order' amplifier cabinets but they cost a bomb so i did not opt for it.

new enclosure..

got new shelf..

started with rewiring for new cabinets:

connectors:

copper bus bar prep.. [it was PITA to drill holes on these plates.. i had to resort to many tactics including using milk for drilling holes!]

power supply up and running in new cab..

with amp board dropped in.. enclosure looks busy and wiring .. ugly

current state!

still in testing..

original plan was to place the amps like below:

but my idea of getting a stand with perforated stacks backfired on me . in the above config below amp is cooking the one above it. and i could see that in the amp measurements!! though perforations help in better air circulation, mono blocks can not be placed one over the other. for now planning to keep one on lowest rack and other on top of the stand. pre-amplifier would stay in the same place. this will leave one floor clear area for lower amp to breath!
it is a PITA to move them around. i should have thought of proper handles for these - each of them weigh around 18kgs. making a stereo amp would have made them too heavy to move around. probably would've used wheeled stand meant for washing machine

measurements:

you can see both the amps measure slightly different. that is the reason it is important to match the components in a build. though it may not produce audible difference in my case but still i would've liked them to have exact same reading. in the above reading Q current is at ~ 1.72Amps . but it can reach up to 1.82 with the rise in mains voltage and i've seen temperature reach up to 55 Degrees Celsius with 25 Degrees Celsius ambient temp. planning to increase bias resistance to bring down the Q current to ~ 1.6 Amps so that the amp performs well even in summer.



my speaker enclosure build is in progress and is being built by the the carpenter recommended on the forum [Babu]. it is being built at his premises since and i've handed him all the dimensions / specifications and other stuff. few stuffs ordered online are yet to reach him. fingers crossed!

 

[HormusPeston]

Those monoblocks will keep you nice and warm in the winter. Great build and very nicely documented!

 

[all4music]

thanks @HormusPeston , they are room warmers for sure.
hopefully temperature will remain within limits during summer. i'll watch them for couple of more weeks for temperature changes [especially if the ambient temperature hits around 35 Degree Celsius]. i might increase bias resistors to bring down Q current if the temperature hits around 60 Degree Celsius.

 

[jls001]

Great build and very nicely documented!

+1 to Hormus.

Really appreciate the effort to document and explain the steps in building and the reasoning behind the decisions? taken. Should someone decide to follow in your footsteps, they have a ready landmark to follow.

Kudos and bravo!

If you will allow me to jump the gun a bit here, what is your listening impression so far?

 

[all4music]

+1 to Hormus.

Really appreciate the effort to document and explain the steps in building and the reasoning behind the decisions? taken. Should someone decide to follow in your footsteps, they have a ready landmark to follow.

Kudos and bravo!

If you will allow me to jump the gun a bit here, what is your listening impression so far?

thanks so much for the kind words.

i start my expectation from a humble point for my DIY builds. first thing if the music is being played from speakers? is it noisy? and later how it sounds compared to my current equipment.
there is absolutely no noise from amps on both Aiwa Speakers and Alpair raw drivers. music listening impressions are great. as i managed to burn one of the Aiwa speakers during the build, i could only test one channel at a time. i'm not good/consistent with explaining audio in words but first thing i could notice is crystal clear and crisp 'Tabla' sound. it is simply great and it beats hands down the current combo -Swans speakers + Yamaha sub [and i hold them in high regards for the budget set up they are]. guitar sounds crisp again. vocals sound soothing and overall i'm very happy about the sound output. but some not-so-great mp3 quality music was almost unbearable to hear. i can give final comments only once my Alpairs are ready [it's gonna be tricky as i'm not sure how they would sound in enclosures]. or probably if somebody else can audition -can put it in better/honest words.

 

[HormusPeston]

The best part about DIY (apart from the pride and satisfaction of building something) is that you can customise the sound system to what YOU like. And it is good that your initial impressions are positive. The full-range speakers that you have planned will work well with jazz, classical and vocal music. Generally, genres that are usually mastered without excessive compression (dynamic range compression, not file-size or codec-linked compression) will sound good. If music is mastered with enough dynamic range it will sound good too -- unfortunately most kinds of rock, metal, grunge, well... almost all genres nowadays, are mastered with excessive compression to make the music sound uniformly louder across all frequencies. In my opinion, full-range drivers tend to sound worse when playing such music. This is not the fault of the speaker or its design. It's just the way the music was mastered. That's just me -- what matters is how the speaker sounds to you. Again, well done and hope you get many years of happy listening from your new system. Cheers!

 

[avesbilal]

Isn't the EMI filter looking too small for this kind of beefy Amp?

I have used a 15 amp EMI filter for my moderate Amp Myref X2.

I'm no expert but though my Transformer was 500va, so thought of using a higher rated EMI.

Regards
Bilal

 

[all4music]

@HormusPeston ,
your comments match very closely with the impressions shared by the users of these drivers on diyaudio.com . let's see how theses turn out to be in this specific box design as i couldn't find any build with this plan. for my electronic music consumption i plan to continue with my current set up. need to find a quick way to choose the output from my preamp! should've thought of this while building the pre-amp

@Bilal ,
i'm not sure since you are referring to physical size of the filter. i picked it up based on the rating. this is rated for 10 amps and my toroidals are rated at 400VA. and i've used 5 amps fuse, so i think this should suffice unless there are other factors that i'm not aware of! so far they have been working fine [i guess since there is no noise!].

 

[avesbilal]

I thought by seeing the form factor of filter that it is 6 amps, and forgot about you are using mono blocks and hence need lesser amps filter, please ignore my comments.

 

[all4music]

Speakers : Alpair 10.3M wide-band driver

i decided on Alpair 10.3M after reading few reviews on diyaudio.com. got the Singapore based dealer details from SaikatBiswas and ordered a pair even before my amp build could be completed.

these come with a recommended burn-in time of 800 hours . as per Dave's recommendation, i let them run in with the help of a jugaad amp.

and after scouting for a good carpenter, i got contact information for a carpenter called Babu - who has earlier worked with many other FM's speaker builds. but in my case the end result did not turn out to be as spec'd. but the carpenter seemed to understand everything explained about the build in the first interaction and assured me of a neat build. i feel even i'm partially to be blamed for this as i allowed him to carry the drivers with him to his place and let him work. and i was busy and been travelling a lot, so couldn't visit him during the build either.


cabinet design is based on a free plan available on frugalphile.com and comes with very neat description and measurements.

issues with my build:
- speakers are not flush mounted
- cabinet is missing the support wedge for the slot port
- cabinet depth is less by 18mm [probably carpenter considered the inner dimension here]

apart from this- the finish left a lot to be desired especially even after i got really hard to get 4mm D type nut and matching Allen Key screws and grill magnets. grill is made of thick wood where termites have already started boring holes.

caught hold of Canare speaker cables!

i like the naked look of drivers better.. but need to use grill to camouflage the shiny thing from my niece!

next to puny Swans Active Monitors..

since these are new speakers to me and i've not come across any build with this specific plan - i'm not sure what to expect. further with the addition of above anomalies i'm not sure if this is how speakers are supposed to sound. speakers have had around 300 hours of run in time on them at the moment. my initial impressions:

- these speakers are meant for vocals. if some music is being played and the moment vocals come into picture - everything else is pushed back. so much so that you feel like the singer is singing right in your ears!
-when only music is being played, it sounds really nice. crystal sound and surprisingly good bass response. i've even switched off the sub in this set-up! as usual, my favorite instrument Tabla sounds clear and sounds very real [not sure if this what is referred to as 'decay'].
-speakers in general sound really loud and vocals take the center stage - if i increase the volume to listen to instruments it gets ultra loud. with the Sub off, low bass sounds is little muted in some of the songs [like in Kannada song 'Dhava Dhava - from movie 'Shhh..']

overall, it doesn't sound bad and since this is my first proper wide band set-up not sure what to expect. hopefully over the next couple of weeks i'll be able to spend sometime in listening to these [loud] monsters and hopefully will be able work on tweaking the response [by Recron fill etc]. fingers crossed!

 

[HormusPeston]

Well done. Glad you liked the sound. I've always felt that full-range drivers are the best for tabla, mridangam and (in my humble opinion) the cello. These are very efficient drivers, so you will not need more than a few watts (5W or so) before they become unbearably loud. At this stage, do not spend too much time with less/more recron.

Pour yourself a nice drink (very, very important) and spend a month of evenings listening to the music that you love.
Cheers, ~hp