Group Buy: Mauro Penasa MyRef Rev C kit

[naren2512]

Thanks Audiodoc,

Do you mean you had compared my ref with Topping TP20 tripath 2020 as well? it will be helpful if you could tell me what all amp you have tried and found the my ref to be better than them ? also could you tell me which speakers ( with normal impedence of 6 ohms and min impedence of 4 ohms) you have paired with my ref amp.. and what is the max volume till which it sings well

Sorry for so many questions.. but just trying to learn with help of you all...

Regards,
Naren

My myref sounds pretty good when compared to the other amps I have heard. Unfortunately my speakers have 4 to 6 ohms impedance while my myref has a power supply tailored for an 8 ohm load so have to play at normal listening levels. Have heard a t amp a few years back so can't compare.

 

[gobble]

somebody told me that Yamaha sells a leniar psu of 12v to use with their keyboard/synthesizer and it is very good at less than 1000/- bucks. don't know the amperes though. Try the local Yamaha showroom.

--G0bble

 

[omishra]

somebody told me that Yamaha sells a leniar psu of 12v to use with their keyboard/synthesizer and it is very good at less than 1000/- bucks. don't know the amperes though. Try the local Yamaha showroom.

--G0bble

One which I repaired recently for Yamaha Keyboard (costly one used by prof.), it was 12V, 5A SMPS. But that can not this MyRef amp. You must be talking in TP20 context.

 

[sachu888]

One which I repaired recently for Yamaha Keyboard (costly one used by prof.), it was 12V, 5A SMPS. But that can not this MyRef amp. You must be talking in TP20 context.

My Yamaha keyboard comes with 12 V SMPS

Regards,
Sachin

 

[Audiodoc]

@naren
I am using the my ref with wharfedale 10.1s current which have 6 ohm impedance however when I tested it with a fluke meter it read 4 ohms. I cannot compare it with a toppling 20 since it has been a while since I have heard one and audio memories are so weak! If I compare it with the midrange of the Norge 1000 which I have modified a lot I love the myref more. The myref sounded very harsh the first few days but it mellowed down with a few capacitor tweaks and breaking in.

BTW the myref needs 28-0-28 v dc for powering 4 ohm speakers and 36-0-36 v for 8 ohm ones.

 

[gobble]

One which I repaired recently for Yamaha Keyboard (costly one used by prof.), it was 12V, 5A SMPS. But that can not this MyRef amp. You must be talking in TP20 context.

Oh Damn!! I refreshed that thread page 4 or 5 times wondering where my post vanished!! :lol: How did I post it here?!!

--G

 

[exljp]

Hi Guys
I managed to complete one board and ready for testing. Can someone give me some idea how to go about checking it with a Multi meter or some other means before really connecting the speakers?

 

[badrisuper]

Me too completed the board, now I want to test it. How to test it. And what other things i needed. What good RCA jack and binding you people suggest?

Badri

 

[Audiodoc]

The details are given some pages earlier when hemant was having some problems. Briefly the testing procedure is to check for the following:

After connecting the power you should hear the relay clicking once.

If you hear the click the DC at the output is within normal limits. Next you will try to determine the amount of DC at the output.

For this set you MM to DC lowest range (<100mV). Connect the prongs to the speaker output and measure the DC offset.

If the relay doesn't click then check this:
http://www.hifivision.com/diy/11495-group-buy-mauro-penasa-myref-rev-c-kit-43.html

And yes post pictures so that we can see if there are any gross mistakes. We won't like you to see the dreaded smoke on first power up.

 

[exljp]

Thanks Audiodoc
I,ll shortly post the pictures

The details are given some pages earlier when hemant was having some problems. Briefly the testing procedure .......

And yes post pictures so that we can see if there are any gross mistakes. We won't like you to see the dreaded smoke on first power up.

 

[badrisuper]

Audiodoc, what is the size of the screw to fix the chip in mount and what is the size of the screw to fix board in cabinet?

 

[jls001]

All this talk reminds me I need to finish my build

Boards are assembled. Need to wire them up and fit them in cab. Only prob is I don't have speakers to use so my motivation is rather low. Hopefully the GR speaker build should drive me to complete this as well.

 

[quad]

All this talk reminds me I need to finish my build

Boards are assembled. Need to wire them up and fit them in cab. Only prob is I don't have speakers to use so my motivation is rather low. Hopefully the GR speaker build should drive me to complete this as well.

Anyways, its better to test with cheapo speakers - I use a pair for which I
paid Rs 150/- which have served me well for testing multiple of my amp builds.

 

[jls001]

Anyways, its better to test with cheapo speakers - I use a pair for which I
paid Rs 150/- which have served me well for testing multiple of my amp builds.

Yes, I bought el cheapo pair - 40 bucks each. Waiting to make noise

 

[Audiodoc]

Same here I use a pair of cheap speakers before connecting my wharfs.

One can use 2 to 3 mm diameter screws with or without washers for mounting the 3886 depending on the size of the drilled hole in the heat sink. I have used 3 mm x 0.5 inch ones for chip and 1.5 mm x 0.5 inch for boards.

 

[doors666]

Yes, I bought el cheapo pair - 40 bucks each. Waiting to make noise

i too need some waste speakers for testing purposes. I presume when you guys are saying speaker, you actually mean woofer? is it full range, do you put a cap or something for protection (though i guess the cap will cost more than the speakers).

 

[Audiodoc]

Yes a speaker should be termed as a 'driver' in technical terms. It may be a woofer, midrange or full range driver or a cheap car speaker.

 

[jls001]

i too need some waste speakers for testing purposes. I presume when you guys are saying speaker, you actually mean woofer? is it full range, do you put a cap or something for protection (though i guess the cap will cost more than the speakers).

Driver, actually. For 40 bucks, one should exempt it from those classifications It is a crash test dummy to see whether it gets blown up or not when the amp is powered up for the first time :lol::lol::lol:

 

[exljp]

I tested the amp briefly and outcome is as below
- I first tried without connecting any speakers and without audio source in, i could hear the relay 'click' sound. I kept it on for just less than 5 secs and switched it off. I have not connected the Heat sink to the IC yet.
- Then i connected with a source from my Marantz FM tuner and also connected the output to a speaker. No volume pot connected. I could hear screetching sound from the speaker and the music could be heard.
- I switched off it immediately and checked the speaker with my multimeter and it shows 3Ohm. I was under the impression that the speaker is 8ohm.
- The transformer secondary output is 24-0-24.

Is the screetching sound due to mismatched speaker? Any help is greatly appreciated.
Few pictures

 

[badrisuper]

Can we test it without heatsink? Yesterday Linuxguru and I were testing the MyRef kit, the same problem occured. But later we realised it is because of the source cable and because of the RCA connection, picking up noises. Suggestion, first try without any source connecting, if the speaker picking up a kind of hum noise, try with another board, if it happens again, then there wont be any problem in the problem, it may be problem with some wiring connection. If there is no noise coming from speaker, then may be problem with speaker wire or speaker. But I guess, speaker is not a problem.

I will post my experience in building my first DIY amplifier, MyRef, little later.

Thanks
Badri