Modifying The Musical Fidelity V Can

After many reviews and gathering opinions (Rock grotto forum) and also with the huge potential offered for this amplifier, I finally decided it was time to give a fresh and more powelfull upgrade to this tiny little geek.

If we want to make it simple, there is a web page form Rock Grotto, where offers you a kit, with all the components to modify. There is a simple kit, with capacitors (35 GBP) and a more comprehensive kit which includes also Opamp (65 GBP). I decided to buy the components, as this gives me more flexibility to tests several alternatives. With this option, the cost is not cheaper but gives me more room to the creativity.

So let’s go for it: I open the enclosure, and get the PCB. First thing I realize is the crappy quality of the components: low cost capacitors (each of them has a cost of 5 cents) ceramic capacitors (not the best alternative for audio), opamp soldered to the PCB with no DIP socket, the resistors are cheap quality and the RCA connectors are very crap and even rotten…

I start to desolder, and all capacitors are removed. Those are Jamicons, just a Nichicon Fine Gold costs more than all the components in the PBC… I remove also the ceramic ones, and the blue capacitors. Initially I thought these blue were tantalum, but finally I think are styroflex, so I decided also to remove them. For the resistors, I remove the gain (R8/R108) and replaced by 5k ohm Holco, and other six resistors. I also desoldered the RCA chasis.

We need to be careful, the PCB is very well built, but the desoldering process must be done with lot of care… I used a electric desolder. As the solder contacts have some Pb (2-4%) the melting temperature is higher than usual.

This is the PCB after all the components were removed:



The serial number of my amplifier is quite strange. I purchased it one year ago, and has a 500XXX serial number. But in the web page of the mods for the V Cans there are some mods done in 2009, with serial numbers of 502XXX. So this means that mine was stored in a warehouse for more than two years? Maybe this is why I got it so cheap from Superfi. Also there is some evidence for this, such as the metallic contacts in the RCA are a little bit rusty…

I received the new components yesterday. After many hours of learning form Head fi.org and Rock Grotto page, and some other clarifications with Vicente (http://www.diyaudio.es/) the first version is ready for installation.

The changes are as follows:First checks… And first issues: The enclosure height, makes the capacitor dimension 28mm as maximum, hence I need an alternative for the Elnas Gold. Also, the capacitor diameter must be checked very carefully, the PCB has a diameter size of 10mm for the “big” capacitors and 9mm for the other caps. As 1000uf caps has a diameter of 12,6mm, and the rest 10.2mm, I have to tight them or even bend the pins to fix in the PCB… Some of them (the big caps of 16mm diameter) requires significant work to be fixed.


 

• Replace ceramic capacitors C8/C108 by WIMA FKP 220 pf 2,5% 500V
• Replace the six capacitors of 100uf and 25V (C3, C6, C7, C103, C106, C107) by Nichicon FG 470 uf 16V
• Replace the 100uf 25V capacitor (C11) by a 1000 uf 50V Nichicon FG
• Replace styroflex (C5/C105) by silver mica 22 pf 500V 0,5%
• Replace the 4.7 uf 63V (C2/C102) by Nichicon Muse BP same values
• Replace the 4,7uf 25V (C4/C104) by Rubycon Black Gate 10uf 100v
• Replace the input capacitors 1000 uf 16V by Elna Gold 2200uf 16V
• Replace the 1000 uf 16V by Nichicon FG 1000 uf 16V
• Replace 8 resistors by Holco 1watt

The RCA are also a pain. The fist I tried has very big diameter so despite fix in the black chassis, is not possible to use them. So I have to try with a smaller Neutrik…

Final component list: The input caps has ben replaced by Muse BP 1000uf 16V, and the Black gates by Nichicon FW 4.7 uf 63V. List in detail of the final parts:

Resistors::Replace 8 resistors by Holco 1 Watt:

• R8/R108 (gain): Replace also the value from 10k Ohm to 5k ohm
• R17/R117: 1k ohm
• R2/R102: 100k Omh
• R18/R118: 47,1 ohm

Capacitors:

• Replace the 2 ceramic caps  C8/C108 by WIMA FKP 220 pf 2,5% 100V
• Replace the six 100uf 25V (C3, C6, C7, C103, C106, C107) by Nichicon FG 470uf 16V
• Replace the 100uf 25V capacitor (C11) by 1000 uf 50V Nichicon FG
• Replace the  styroflex  (C5/C105) by silver mica 22 pf 500V 0,5%
• Replace the 2  4.7 uf 63V (C2/C102) by Nichicon Muse BP same values
• Replace the 4,7uf 25V (C4/C104) by Nichicon FW 10uf 63V
• Replace output caps (C10/C110) 1000uf  16V by Nichicon Muse BP same values
• Replace input caps (C1/C9) 1000uf 25V by Nichicon FW 2200uf 25V
• Replace the C12 100uf 25V by Nichicon FG 1000uf 16V

The operating table, with all the required elements: Solder, soldering wire (60/40) with 0.5mm and 1mm diameter, helping hands, multimeter, wire cutters and capacitors:

 

Lets go for it: First we solder the resistors, measuring with the multimeter the right values (despite each resistor has clearly the value on the front)

Now the 14 pins socket. Is quite laborious to solder 14 pins, so I must be sure that the socket is fully aligned in the PCB. I solder first the opposite pins.

Then we go with the WIMAs, and the silver mica. Initially I assumed the blue ones were tantalum, in fact I did not see why Rock Grotto mods did not replace these. Raul_77 finally confirmed then are styroflex caps. Anyway I replaced them, but I can test with both to see what is better.

 

The Opamp is a LME49740

Next step is the left and right caps with the Fine Gold 470. The only complexity is to bend the FG 470 closer to the extreme (between caps and resistor)

Now MUSE BP, the audio caps. With such a huge diameter, I have to bend the legs as there is not enough room. The Holco resistor size is not helping, anyway…

The small Muse BP I have to move to the sides, because I need room for the biggest cap, a FG 1000 50V. I had to check if the length was enough, but finally was Ok. If you prefer other alternatives so you don’t want to lie the cap, try with a FW 1000 50V, or a Panasonic FC 1000 50V (26mm high) 

The last caps (FW2200 and FG 1000) requires some fine tuning, as there was not enough room. You can see below the difference between theoretical diameter and finally where is placed the cap (FW2200).

The last action is to  get the case grounding optimal.... the ground tag fits between the rear plate and the enclosure.... the enclosure is coated with a thick layer of paint... where the ground tag meets the enclosure, so according to Rock Grotto (Mike) suggestions to improve, I scrape the paint off with a dremel. 

Some future enhancements is to replace the crappy RCAs by Neutrix, and some work for the power supply…

So everything is ready, this is how looks like:
 

I putt the PCB into the enclosure, finger cross… and everything fits Ok. The Muse caps tights very closely, I don’t think is even half a mm spare. I screw the back, and connect the power. Everything sounds fine, despite is too soon to have a real measurement of the improvements.

The last detail is to replace the plastic knob by a black aluminum knob, much stylized.

APPENDIX: List of concerns and mistakes:

• During the desoldering process, some of the PCB contacts lost some of the metallic part, so the soldering is not perfect, despite there is enough contact. I assume everything is fine, otherwise the apm would not work.
• If I turn the volume to the maximum level, with the Ipod in pause, there is a noise (similar to bird sing J) I think is an issue due to the connector cables quality.
• The voltage in some points can be poor, due to the PCB size limitation. There was no room for some of the 25V caps. After some time burning everything looks fine. Mike Grotto in fact proposes 16V capacitors in some places, despite for me is not ideal.
• To stick the 14 pins DIP socket to the PCB, I decided to use some blutack to ensure no movements during the soldering… Fucking hell, to remove the blutack was a pain in the ass….