Some questions regarding the Mark-IV in general

[phrygiandom]

Got a couple of general questions regarding my recently purchased Mark-IVA head:

1. Are the push/pull pots still produced by MESA? I've tried in vain to tighten them. The previous owner actually broke the screw head on the Master Volume. Or is the extra slack in the pot just something that comes with age of the amp?

2. If running a wet/dry/wet setup, would it be best to use the Slave or Recording out? My guess is that the best sound quality would come from the Recording out, but the book suggests Slave out.

3. If I were to build a plexiglass "tube shield" for the back of the amp (covering the area that the footswitch would cover) would it seriously impede cooling during operation? I've read that there were cooling issues with the earlier Mark-IV's.

4. Is the footswitch as delicate as it seems? I'm a bit concerned about the cable being hardwired to the footswitch....and terrified of someone stepping on it and breaking it off.

I appreciate any input that you may have.


Dave

 

[Mongo1]

Dave,

1. Are the push/pull pots still produced by MESA? I've tried in vain to tighten them. The previous owner actually broke the screw head on the Master Volume. Or is the extra slack in the pot just something that comes with age of the amp?
I needed a new pot for the Lead Drive (shaft snapped off clean, pot still worked fine) and Mesa had it in stock. Best thing to do is call them and check.

2. If running a wet/dry/wet setup, would it be best to use the Slave or Recording out? My guess is that the best sound quality would come from the Recording out, but the book suggests Slave out.
Having never used them I'd say, let your ears be the judge.

3. If I were to build a plexiglass "tube shield" for the back of the amp (covering the area that the footswitch would cover) would it seriously impede cooling during operation? I've read that there were cooling issues with the earlier Mark-IV's.
I would not recommend impeding any air flow into the back. You 'might' get by with a narrow aluminum plate if you relocate the fan to a location that allows better air flow. I know the stock fan location (at least on my MKIVa combo) was practically sitting on the reverb pan and had limited air flow.

4. Is the foot switch as delicate as it seems? I'm a bit concerned about the cable being hardwired to the foot switch....and terrified of someone stepping on it and breaking it off.
I replaced my hard wired foot switch wire with a Neutrik 6 pin connector back in 95. This ended my tangle of wires I was 'carefully' shoving in the back of the amp during tear down, all the while trying not to burn any on the hot tubes. I also cut off a 5ft. section of the wire and added ends to it. This gave me a short cable to use when I just wanted the switch in front of the amp. One added bonus I gained was that by putting the connector on the foot switch, it also allowed me to wire the foot switch into my long snake by using (2) of the channels and connecting 6 pin ends.

All in all, the foot switch mod has been great. In 13 years, it has not had 1 problem. The Panel Mount connector I wired into the foot switch didn't fit perfectly with the screw holes (as seen in the pictures), but it was close enough to be secure and sufficient.

I believe these are current versions of the parts I used.
Verify them to be sure.
6 Pole Panel Mount Connector
http://www.neutrik.com/us/en/audio/210_t2_346005876/NC6MP-BAG_detail.aspx

6 Pole Rt. Angle Connector
http://www.neutrik.com/us/en/audio/210_t2_701166793/NC6FRX-B_detail.aspx

6 Pole Straight Connector
http://www.neutrik.com/us/en/audio/210_t2_956058614/NC6FX-BAG_detail.aspx

 

[phrygiandom]

The mod to your footswitch is EXACTLY what I need to do. That's definitely my next project. Thanks for sharing the pics.

 

[MrMarkIII]

The "slack" in the potentiometer is normal. The knob is not slipping on the shaft.

 

[Mongo1]

Glad to help.