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2013 Ampeg V-4B 100W Reissue Pt2

#1,062
kd5uwl said:
Hey V4b-ers, is there any magic or secret trick to getting my test probes through the thick white silicone rubber on the leads of the 6L6 cathode resistors? Maybe there is no other way - I don't see what it could be if there were another way to measure the voltage drop across those resistors, but I thought I would ask the experts here. It works the way I did it, you just have to exercise care.
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The coating is there to affix the part and it insulates. You can stab through it with the probe tip, the silicone is self healing. You can carefully remove a small area, just don't scrape the wire or the protective tinning will be removed and oxidation can set in. Not a big deal if it does.

Rather than measuring across the cathode resistors, R12, R13, R14, and R15, you can measure from pin-8 of each 6L6GC to ground which is across the resistor. This isn't as safe, it is easy to slip off the tube socket and cause a short. The resistors are supposed to be there to make the bias procedure easier.
 
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#1,066
Not quite the same but I run my vintage V4 with my PF-210 cab from time to time. A decent pairing. I still find the PF-210 a little stiffer than I like but I don't use it all that often so I'm probably just more used to the sound of my vintage cabs.
 
#1,069
beans-on-toast said:
The coating is there to protect you. You can stab through it with the probe tip, the silicone is self healing. You can carefully remove a small area, just don't scrape the wire or the protective tinning will be removed and oxidation can set in. Not a big deal if it does.

Rather than measuring across the cathode resistors, R12, R13, R14, and R15, you can measure from pin-8 of each 6L6GC to ground which is across the resistor. This isn't as safe, it is easy to slip off the tube socket and cause a short. The resistors are supposed to be there to make the bias procedure easier.
Click to expand...
Why not buy a Bias Rite with the plate volt option?

My days of poking around in an amp chassis are over......only when absolutely necessary and I would rather have my tech do it.

With a Bias Rite w/plate volt option you can calculate total dissipation at the flick of a switch.
 
#1,070
DavidEdenAria said:
Why not buy a Bias Rite with the plate volt option? My days of poking around in an amp chassis are over......only when absolutely necessary and I would rather have my tech do it. With a Bias Rite w/plate volt option you can calculate total dissipation at the flick of a switch.
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A bias tool is safer, but it's an extra expense that many don't want in incur. You still have to get into the chassis to adjust the pot which negates some of that added safety by using a bias tool. External test points and pots like that did on the vintage SVT is so much better. It reduces the cost of the amp the way that they did it, but it makes sense to me to pay a little extra and do it right. Amp design is full of compromises driven by the bottom line.

This is the procedure that Ampeg published on TB. It is intended for a qualified tech to perform.

 
#1,071
Tone for days! Proud to be reppin the 'peg!! What are your guys' settings?
 

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#1,074
rulyongo said:
A question for B- 4V users. I used to play through a Svt classic but got tired of hauling it around for gigs. For a few years played through an Orange Terror Bass, but been longing for that Ampeg tone. So, the question is, can the B-4v handle loud gigs? I tried it in a store and loved it's tone.
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A lot depends on your cab and how loud "loud" is to you. It ain't quiet in an 810, that's for sure. But it may be too quiet for some. Never was for me, though. My loudest years were using a V4B into an 810.
 
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#1,079
Wow and damn, that cab looks brand, spanking. You sure you wanna take all that classic cloth off that gorgeous cab. How old is it?
I read in another thread where a TBer was gona change the smaller amount of cloth on his amp head instead of all the cab cloth for the match. Just a thought. Your rig; do what pleases you. Pls post back with pics once you're done.
 
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