Group Buy: Mauro Penasa MyRef Rev C kit

[gobble]

Gobble, Thanks for asking man, too much tech stuff for me to comprehend, i have a nad c320bee and wharf 9.2, could you please throw some more light?

Here

Careful ... please put on your goggles

cheers

 

[santhosh]

Here Careful ... please put on your goggles
cheers

I had not come across this thread before. But, the light at the end of the tunnel...err thread led me here:lol:

 

[linuxguru]

Any progress on this guys ? It maybe rude to ask this knowing that the OP was sick etc....but since I opted in last, didnt want to be left out ...

Don't worry - the schedule on the PCB has slipped by about 2 weeks, but components have been sourced in parallel, so it's not all wasted. Only two difficult components - a 150pF capacitor in silver-mica/polystyrene/polypropylene and a 100nF Wima MKP/FKP polypropylene film capacitor in 7.5/10mm pitch are not available locally, but I have found (and tested) acceptable substitutes. I don't expect any passive component shortages, at least for the first 50 kits or so. The LM3886TF chipamp may be a problem in quantity, but it should not take more than a week to source more - it's a regular channel item.

I will be ordering around 50 PCBs for the initial batch, so there will be no shortage of PCBs, even for the late arrivals to the group buy. Depending on availability, a few bare PCBs may also be available after the kit orders are filled.

 

[stereorules]

thanx for the update ...

 

[gobble]

Don't worry - the schedule on the PCB has slipped by about 2 weeks, but components have been sourced in parallel, so it's not all wasted. Only two difficult components - a 150pF capacitor in silver-mica/polystyrene/polypropylene and a 100nF Wima MKP/FKP polypropylene film capacitor in 7.5/10mm pitch are not available locally, but I have found (and tested) acceptable substitutes. I don't expect any passive component shortages, at least for the first 50 kits or so. The LM3886TF chipamp may be a problem in quantity, but it should not take more than a week to source more - it's a regular channel item.

I will be ordering around 50 PCBs for the initial batch, so there will be no shortage of PCBs, even for the late arrivals to the group buy. Depending on availability, a few bare PCBs may also be available after the kit orders are filled.

Are you outsourcing the PCB stuff? 50 is a lot to make for one person ... or isnt it?

Cheers

 

[borg]

two monoblocks for me please
let me know the payment method as well

 

[cooltoad]

hehe....that was funny!

Here

Careful ... please put on your goggles

cheers

 

[cooltoad]

How much a completely built stereo unit costs? sorry if it is already available in some previous posts.

 

[linuxguru]

How much a completely built stereo unit costs? sorry if it is already available in some previous posts.

At the moment, only kits (PCB + all parts on the PCB) are being offered at Rs.1.5k per monoblock, or Rs.3k for two monoblocks (stereo). You will need additional parts to assemble a fully-packaged amp.

 

[Kittu]

At the moment, only kits (PCB + all parts on the PCB) are being offered at Rs.1.5k per monoblock, or Rs.3k for two monoblocks (stereo). You will need additional parts to assemble a fully-packaged amp.

What would be the cost for a fully-assembled amp ? with linuxguru logo

 

[sachin_k5]

two monoblocks (stereo) for me too. let me know how to make the payment.

Also someone please plan a group buy for good quality transformers !

 

[cmsajith]

What would be the cost for a fully-assembled amp ? with linuxguru logo

How about a brand name : LG??? (LinuxGuru)

 

[GeorgeO]

I volunteered to do it with Miracle, someone else can check with another vendor. I'm assuming that the specs are a single primary for 220-240 and secondaries are 32-0-32, 5A. Once we get confirmation of these specs, I would like interested parties to confirm on another thread-so that this one doesnt get clogged with transformer info.

ALL: Please note, by volunteering I will not be able to do anything more than try to get a group discount provided everyone orders at the same time-if anyone expects any more value addition, I will stand down, and ask for someone else to volunteer. I will be happy to pass on contact info of Miracle to the designated volunteer.


Should anyone have any suggestions that are easy to implement, please speak up!

Cheers

George

two monoblocks (stereo) for me too. let me know how to make the payment.

Also someone please plan a group buy for good quality transformers !

 

[gobble]

We should check with Delta transformers as well Delta Transformers


I will need a Trafo that can be used for both Pass Labs F5 and the GC. Multiple secondary windings maybe? Need to work out the specs and see if it is feasible.

How about a brand name : LG??? (LinuxGuru)

We may need to sue LG for using it already ... hyeah:

Cheers

 

[keith_correa]

We should check with Delta transformers as well Delta Transformers

I see that Delta makes R-Core trafo's too. Can anyone educate us of the differences [benefits? pitfalls?] of R-Core vs. Toroids?
Also, Miracle has a "Volume Control Audio Attenuator" that could be used instead of a pot or stepped attenuator. I read that these are much better than pots/stepped attenuators. Only problem I see is that Miracle's product offers 11 steps whereas more steps may be desired.

 

[borg]

I see that Delta makes R-Core trafo's too. Can anyone educate us of the differences [benefits? pitfalls?] of R-Core vs. Toroids?
Also, Miracle has a "Volume Control Audio Attenuator" that could be used instead of a pot or stepped attenuator. I read that these are much better than pots/stepped attenuators. Only problem I see is that Miracle's product offers 11 steps whereas more steps may be desired.

toroid tfr (because of the construction) will have more interwinding capacitance than R core ,meaning there is a chance of more HF noise from mains coupling through. However this can be mitigated by using a electrostatic shield between primary and secondary

R type will be costlier imho

 

[GeorgeO]

Since I have had some contact with JP Singh of Delta, let me email him once I have the transformer specs confirmed and ask him if he can also quote.

George

toroid tfr (because of the construction) will have more interwinding capacitance than R core ,meaning there is a chance of more HF noise from mains coupling through. However this can be mitigated by using a electrostatic shield between primary and secondary

R type will be costlier imho

 

[linuxguru]

The transformer is 24-0-24, 5A, i.e. 240 VA. This translates to DC rail voltages of approx. (1.4142 * 24V) - 2V ~= +/- 32 V, which is the recommended rail voltage for the MyRef.

You can get conventional EI-core transformers (e.g. SHAM brand) with these specs. for ~ Rs.500, but they'll be bulkier than a toroidal. An EI-core 50-Hz transformer needs approx. 1 sq.inch of core cross-sectional area for every 100 VA of output.

A toroidal with these specs. will probably be over Rs.3k, but you need to check with Miracle, Delta, Salzer, etc. to see if this is a standard, off-the-shelf transformer. You can manage with a 4A or 6A secondary if that's what is available.

Edit: The Miracle standard-product M22550 225VA, 2 x 25V, 4.5A will fit the bill. The M22544 will also work, albeit with slightly lower audio power output.

http://www.toroidal.com/Product1.aspx?Pid=10&Lid=English

 

[GeorgeO]

This is for a monoblock/dual mono I assume? What about for a stereo amp, if a single tranny is used?

Thanks

 

[linuxguru]

This is for a monoblock/dual mono I assume? What about for a stereo amp, if a single tranny is used?

This is for dual monoblocks, which requires the same single transformer configuration as a stereo - the two 25V secondaries are connected in series to get a 25-0-25V secondary, which is connected in parallel to each channel at AC1-PGND-AC2.