MV-55 anyone with experience of this?

[DarrellMcM]

Hi, I am considering getting an MV-55 and wanted to ask if anyone has experience of this amp can advise of any common issues it may have, just so I am aware.

Thanks in advance.

[admin]

First, welcome to CJO. Great to have you with us.

As a owner of an MV-55, I can say it's a solid beast-of-a-machine but with a very delicate sound. The MV-55 was one of the most popular units in CJ history. I think that speaks plenty. I'm not sure what kind of "issues" you may be referring to? I suppose one can argue that any electronic equipment is going to be prone to failure at 25+ years out, but I am not aware of any specific design flaw that would cause expectant issues.

[roberto]

Admin just said it: This unit is bullet proof. Also, I don't know of any issues with this particular model. Of course, a unit with over 25 years you should have a serious listening before you get it. But usually the unit will sing beautiful. Those EL34s/6CA7s tubes are well known as a crystal crispy sound, and of course, the unit has the Conrad Johnson signature sound quality.

Aways on tubes, it is a good idea to put fresh tubes, specially the small signal tubes, they are always the culprit of odd noises, not the amp itself. If a tube, while adjusting the bias, the LED bias goes off, still there is juice from it.

Happy listening!

[RJKflyer]

(Sorry - bit late to this conversation but only just spotted it).

Having owned a MV-55 for nearly 30 years I can attest to it being a very sweet performer, and so much so that this month I chose to perform a few minor upgrades to assure its future.

in terms of what I have observed, accepting I am but a single data point:
1. The heater rectifiers run hot and I experienced what I thought was a failure but may well have been a dry joint exacerbated by the heat - there are superior replacements to use here. I used Vishay SBYV28-100-E3/54 which confer faster operation, softer recovery and less dissipation
2. The heater electrolytic merits replacement after so many years. Mine was showing signs of aging and leakage was more than I would like. Another easy repair, and a higher temperature, longer hours, and higher value of a top brand like Nichicon or M-lytic can be substituted
3. I would replace as a matter of course the other 4 electrolytics (2 x 220µF on the supply to the bias op-amps) and 2 x 47µF 160V elsewhere).
4. Take the fuses out and clean the ends and clips!

I won't get into other upgrades as this was not your question. What I would say is that the existing film caps are of extremely high quality as even where I did elect to upgrade, the originals were exhibiting sub-µA levels of leakage at rated voltage.

As wisely suggested by Roberto, give it a careful listen, notably for Hum (suspect heater supply to small signal tubes) and any crackling/hiss (suspect small signal tubes).

What I absolutely would suggest is to withdraw each tube carefully and clean thoroughly the pins with Deoxit or similar. Then using a suitable device such as a sharpened wooden toothpick soaked in same, clean each socket pin, being careful obviously not to open them up. The sockets in this and any tube device of this age will be tarnished and slightly dirty pins can and do give rise to crackles, pops and hisses.

[admin]

Sounds like these upgrades will keep the MV-55 running flawlessly for many years to come.

May I ask how much all the replacement parts cost? As a fellow MV-55 owner, this is something I may consider doing in the future.

[RJKflyer]

Let me post a separate thread on that.