Group Buy: Mauro Penasa MyRef Rev C kit

[captrajesh]

Nice! Where did you get the HS from? How much? dimensions? fin size?

The dimensions of heatsink I'll have to measure but I think it is 10" x 2" & we got it for Rs. 150/-

More about the SQ please?

Hey cap'n! Looking good, there. How does it compare with the 'D'?

The amp really excels in low frequency extension. I'm sure it will drive even low efficiency speakers with much elan. The mids and highs are a bit bright to my liking. I'm yet to have a detailed listening session to post about it's SQ. The amp is back to the workshop for a modding job. We are fitting it with a better and linear pot. I've also bought an old Technics Amp with an intention to junk it's innards and put this amp into it.

In comparison, the class D really excels in mids. It does not have a big sound stage but there is immediacy to the music. The instrument separation is great. However, it is weak in the slam department. I have a feeling that this is due to the transformer. Hope to check that out. One of our forum members is also building a class D amp from the same company. I'll probably take my amp and try to run it with his trafo to see the difference if any.

 

[grubyhalo]

Cap'n, don't forget the power cap upgrade on the PS...

 

[captrajesh]

Cap'n, don't forget the power cap upgrade on the PS...

Yes Gruby, I'll first see if there is any improvement in the slam dept and then probably go for the upgrade.

 

[gobble]

The mids and highs are a bit bright to my liking. I'm yet to have a detailed listening session to post about it's SQ.
...
In comparison, the class D really excels in mids.

Do check which resistors you got for R1 and R4: The new "My Ref" Rev C thread - Page 107 - diyAudio
Siva reported a metallic tinge to the SQ earlier which he fixed by changing choice of resistors.

Also you can try if you feel like experimenting:
The new "My Ref" Rev C thread - Page 106 - diyAudio


Cheers

 

[linuxguru]

The amp really excels in low frequency extension. I'm sure it will drive even low efficiency speakers with much elan. The mids and highs are a bit bright to my liking. I'm yet to have a detailed listening session to post about it's SQ. The amp is back to the workshop for a modding job. We are fitting it with a better and linear pot. I've also bought an old Technics Amp with an intention to junk it's innards and put this amp into it.

Allow it to burn in for 5-10 hours and check for the brightness in the mids/highs again. If it seems smoother, then it's just the Panasonic FC caps (C1, C2) and the main Panasonic PSU caps (C3, C8) that are bedding in, and the brightness should decrease/disappear after a while.

If there is no perceptible improvement after 10 hours, perhaps a mod to C21 may help - a 22nF Wima MKP to bypass C9 (180uF/16v polymer).

The next mod is to replace R3 (2 x0.22/2W carbon film) with a single 0.47 ohm, 5W non-inductive, non-magnetic metal-plate resistor like a HTR, Futaba or Caddock.

The next mod after that is to replace R9 (12k) with a 2W premium resistor - something smoother/softer like a Kiwame or Holco H4 metal film, or even an Allen-Bradley Carbon Composition resistor, would fit the bill. All three are out of production now, but NOS parts are still available on EBay from time to time.

The final mod (a big upgrade, actually) is to replace C6, C9 and C11 with Rubycon Black Gates - which are also out of production and becoming unobtainium.

I'll try to bring whatever parts I can get my hands on, on my next trip to Chennai.

The Technics cabinet is a good choice for a MyRef stereo box - inexpensive, and has lots of usable components (trafo, heatsink, switches, controls, connectors, etc.) already in place.

 

[captrajesh]

The dimensions of heatsink I'll have to measure but I think it is 10" x 2" & we got it for Rs. 150/-

The exact dimensions are, 23.5 cm x 4 cm. It becomes quite warm after some use.

I've also bought an old Technics Amp with an intention to junk it's innards and put this amp into it.

Guess what, I asked for a dead amp and got this amp Technics SU-8022. Before junking the innards, I had just plugged it & viola the LED glowed. I had a gut feeling that the amp would work.

So cleaned up the aux inputs and connected it to a pair of bookshelves that are connected to DTH and hooray, the amp is fully functional and guess what sounds really special.

The ironic part is, I'm now saddled with 4 stereo amps and three sets of speakers and two CDPs but no space to keep them.:sad:

 

[keith_correa]

Guess what, I asked for a dead amp and got this amp Technics SU-8022. Before junking the innards, I had just plugged it & viola the LED glowed. I had a gut feeling that the amp would work.

So cleaned up the aux inputs and connected it to a pair of bookshelves that are connected to DTH and hooray, the amp is fully functional and guess what sounds really special.

Where on earth do you get this stuff from? Lucky you.
Does the Technics sound better than your Lux?

 

[linuxguru]

Guess what, I asked for a dead amp and got this amp Technics SU-8022. Before junking the innards, I had just plugged it & viola the LED glowed. I had a gut feeling that the amp would work.
...
The ironic part is, I'm now saddled with 4 stereo amps and three sets of speakers and two CDPs but no space to keep them.:sad:

Captain, since you wanted a dead amp, I'll swap a Technics SU-8011 with one dead channel for your working SU-8022 .

(The SU-80xx integrated amps have a nice discrete phono section that can easily be restored by capacitor upgrades, but the power amps are generally low-end STK-00xx darlington output modules. However, they can sound fairly sweet, as some them were using Rubycon Black Gate C coupling caps long before they were "discovered" by the audiophiles and prices went to the stratosphere.)

 

[Hiten]

The amp really excels in low frequency extension. I'm sure it will drive even low efficiency speakers with much elan. The mids and highs are a bit bright to my liking. I'm yet to have a detailed listening session to post about it's SQ. The amp is back to the workshop for a modding job. We are fitting it with a better and linear pot.

Nice work captain. Hope the mods work for you.

 

[captrajesh]

Captain, since you wanted a dead amp, I'll swap a Technics SU-8011 with one dead channel for your working SU-8022

Actually, the Technics amps sounds special. My position is like that of the protagonist in a 70s film song "Kisko pyar karu"

The Luxman sounds sweet with overtly lush mids and nicely rounded off highs and pleasant sounding lows but the Technics sounds clear, clean and clinical.

(The SU-80xx integrated amps have a nice discrete phono section that can easily be restored by capacitor upgrades, but the power amps are generally low-end STK-00xx darlington output modules. However, they can sound fairly sweet, as some them were using Rubycon Black Gate C coupling caps long before they were "discovered" by the audiophiles and prices went to the stratosphere.)

Will seek your advice on the mods to be taken up.

Nice work captain. Hope the mods work for you.

Thank you Hiten. I'm not modding the amp with Linuxguru's suggestion immediately. With the choices of amps that I presently have, I will take my time on that.

That reminds me, I've now learnt that ordinary lead was used for soldering instead of silver-lead.:sad: I don't think de-soldering and re-soldering is worth the effort.

 

[Hiten]

That reminds me, I've now learnt that ordinary lead was used for soldering instead of silver-lead.:sad: I don't think de-soldering and re-soldering is worth the effort.

Sorry to hear that

My position is like that of the protagonist in a 70s film song "Kisko pyar karu"

:lol:
------------------------------------------------------------------------------------------------------------
I would suggest keep the amp which has good specifications and is in good condition, and has more power to drive different speakers and can play all types of music well. Hope this helps

 

[captrajesh]

I would suggest keep the amp which has good specifications and is in good condition, and has more power to drive different speakers and can play all types of music well. Hope this helps

@hiten, if you have an option of dating 4 of our Bollywood beauties and someone suggests you to keep only one, what will you decide?hyeah:

The one which has good specifications
OR
The one in good condition
OR
One that has more power to drive different speakers
OR
One that can play all types of music well

:lol::lol:

 

[Hiten]

yes captain, very difficult to decide.
you better make room for all........ the amps I mean :lol:

 

[kaushik]

i have auditioned with the amp kit bought by member Anil .....very good resolution and dynamics, worth the money for sure
we have used panasonic 10,000uf caps .

 

[gobble]

That reminds me, I've now learnt that ordinary lead was used for soldering instead of silver-lead.:sad: I don't think de-soldering and re-soldering is worth the effort.

4% silver is solder lead is not a magic cure I would suppose, although I would avoid using regular variety as far as possible.

Cheers

 

[captrajesh]

Hey Gobble,

Any idea which one to keep

I mean the amps. I was expecting replies from you and suri.

 

[gobble]

Hey Gobble,

Any idea which one to keep

I mean the amps. I was expecting replies from you and suri.

I would say - keep your other amp in another house, find a new well decorated home for it. Divide your time and income (for upgrades to matching speakers and ICs etc) equally between both amps.

.... And you should know this already but yeah - never tell one amp you are going to listen to the other ... hyeah:


Cheers

 

[captrajesh]

yes captain, very difficult to decide.
you better make room for all........ the amps I mean :lol:

I would say - keep your other amp in another house, find a new well decorated home for it. Divide your time and income (for upgrades to matching speakers and ICs etc) equally between both amps.

.... And you should know this already but yeah - never tell one amp you are going to listen to the other ... hyeah:

:clapping:

ROFTL

:lol::lol::lol:

 

[linuxguru]

That reminds me, I've now learnt that ordinary lead was used for soldering instead of silver-lead.:sad: I don't think de-soldering and re-soldering is worth the effort.

Don't worry, I don't think there's any audible difference between 60:40:0, 63:37:0 and 62:36:2 Snb:Ag solder. Most of the differences relate to ease of soldering, wetability and flow characteristics. The silver solder is recommended for soldering on bare copper or gold, because the intermetallic compound between Cu:Ag and Au:Ag has good conduction as well as mechanical properties.

On another note, I forgot the most relevant mod to the MyRef kit: Use a high quality polypropylene film/foil input-coupling cap (C13) like a Solen, Obbligato, Mundorf or similar. Some of the Russian military-surplus Teflon, PIO and PETP caps on EBay are also getting good reviews.

You can use these to either replace or bypass the 4.7uF/63V film cap supplied in the kit. If you bypass it, you can use a small value like 47 or 100 nF without losing bass slam, while at the same time getting cleaner highs.

 

[linuxguru]

i have auditioned with the amp kit bought by member Anil .....very good resolution and dynamics, worth the money for sure we have used panasonic 10,000uf caps .

Cool - where did you get the Panasonic 10,000 uF in Bangalore? I gave Anil the stock kit with Panasonic 6800 uF/50V, which is also the same in Captain Rajesh's kit. The stock Panasonics are good value for sure, but I'll probably be running out of those shortly, so I need to scout for good replacements.