Ampeg v4b volume 1 Potentiometer

[agedhorse]

So, presuming that I ve an A log taper in the amp, how is the log a taper and the 1 meg linear influence the gain structure when you turn the volume up.. I mean something like 1 will make the amp reach the crunch early, and another maybe later?? Or, for instance, what difference should I notice compared to what I've now on channel 1 when I turn the volume up?

The level will come up really fast and after 12:00 will only get a little bit louder.

 

[Sunnampeg]

The level will come up really fast and after 12:00 will only get a little bit louder.

So if I've understood well, the 1 Meg linear will reach the louder volumes and overdrive early, and the A log taper will reach later louder volumes and overdrive, and it distributes the power in a more even way on the entire run of the potentiometer. right?

 

[agedhorse]

So if I've understood well, the 1 Meg linear will reach the louder volumes and overdrive early, and the A log taper will reach later louder volumes and overdrive, and it distributes the power in a more even way on the entire run of the potentiometer. right?

Correct, generally a log pot in that location will feel (a lot) better and be more usable.

 

[Sunnampeg]

Correct, generally a log pot in that location will feel (a lot) better and be more usable.

Thanks, with this information, I don't understand how they can sell it as a pot replacement for amps with not much headroom, like Svt 70s or even worse, V4B 70s. It seems it will make the volume of your amp unmanageable. Someone should tell them it is not the right replacement

 

[agedhorse]

Incorrect parts get sold all the time, I see it in amps that have had repair attempts made. Always costs more to then fix it right.

 

[Stylee Mousse]

I’m sure my magnavox era 70s v-4b has Lin volume pots.

These days I really never go past 10 o’clock to get the volume and touch characteristics I like.

For the years my wife gigged that head she would ever so slightly ride this little arc between 10:25 and 10:35, marked on the faceplate with a China marker.

That would be the difference between “just right” and tool loud!

 

[Sunnampeg]

I’m sure my magnavox era 70s v-4b has Lin volume pots.

These days I really never go past 10 o’clock to get the volume and touch characteristics I like.

For the years my wife gigged that head she would ever so slightly ride this little arc between 10:25 and 10:35, marked on the faceplate with a China marker.

That would be the difference between “just right” and tool loud!

Mine is a Magnavox era, and here it is what I've found: it is not linear, it is A log taper 220663-3 1 meg 1377450

 

[agedhorse]

There you go, sometimes the truth is surprising!

 

[Stylee Mousse]

Not a huge surprise, given the way factory-floor substitutions were often done.

If your (sunnampeg) v-4 is the one in your pic, I definitely have an earlier one. Mine has the metal knobs and metal power and standby switches. It may have been built, in some measure, Ampeg Linden N.J. parts

 

[Sunnampeg]

There you go, sometimes the truth is surprising!

ahahahah.

 

[beans-on-toast]

Mine is a Magnavox era, and here it is what I've found: it is not linear, it is A log taper 220663-3 1 meg 1377450

You have it backwards, the image is a 1M linear pot. Based on the pot codes, 1377450 means that it’s a CTS pot made in the 50th week of 1974. Your amp was probably made in early 1975. The other code is the Ampeg part number, 220663-3 is a 1M Linear pot.

I posted a parts list pdf file above. From that file: -3 is linear; -18 is log

So the correct pot for your amp is 1M Linear.

 

[Sunnampeg]

Not a huge surprise, given the way factory-floor substitutions were often done.

If your (sunnampeg) v-4 is the one in your pic, I definitely have an earlier one. Mine has the metal knobs and metal power and standby switches. It may have been built, in some measure, Ampeg Linden N.J. parts

Yes mine should be a 76 or 75.

 

[agedhorse]

This is when you should measure your part to see what it really is.

 

[Sunnampeg]

You have it backwards, the image is a 1M linear pot. Based on the pot codes, 1377450 means that it’s a CTS pot made in the 50th week of 1974. Your amp was probably made in early 1975. The other code is the Ampeg part number, 220663-3 is a 1M Linear pot.

I posted a parts list pdf file above. From that file: -3 is linear; -18 is log

View attachment 7272741

So the correct pot for your amp is 1M Linear.

Bah we will see, this is for the V4 or v4b? There could be differences between those 2.. why there is often 1 meg linear 1 meg log or 100m k lin 100k log

 

[Sunnampeg]

This is when you should measure your part to see what it really is.

sorry i m not following.

 

[coreyfyfe]

must be something wrong on because when i search that part what comes out is a taper LOG and not a linear..

Where are you searching and finding log taper?

The part list shows linear.

The schematics show linear.

You have the pot. Measure it and see.

 

[agedhorse]

Where are you searching and finding log taper?

The part list shows linear.

The schematics show linear.

You have the pot. Measure it and see.

The information I have shows a log pot, though there were several versions of this amp and there MAY be differences.

sorry i m not following.

You need to measure the pot to see if it tracks as linear or log.

Set the control to 50% and if the readings are equal between the center terminal and each of the side terminals then it's linear. If it's very different, then it's log.

This is the first thing a qualified tech would do, to determine what the part is and if the part is correct to the schematic.

 

[Sunnampeg]

The information I have shows a log pot, though there were several versions of this amp and there MAY be differences.


You need to measure the pot to see if it tracks as linear or log.

Set the control to 50% and if the readings are equal between the center terminal and each of the side terminals then it's linear. If it's very different, then it's log.

This is the first thing a qualified tech would do, to determine what the part is and if the part is correct to the schematic.

Hi yes, I will ask. He has dismantled the pot piece by piece, cleaned it, and has probably already done it. But I will ask to make sure.
So, with the number part, do you think it's a log taper?

 

[agedhorse]

hi yes, I will ask. He has dismantled the pot piece by piece, cleaned it, and has probably already done it. But I will ask to make sure.

That’s not how a pot gets replaced… and it’s measured without any disassembly.

This logic makes no sense at all.

 

[Sunnampeg]

He cleaned the pot and the pot does not make any noises at all, but he has already put it back into the amp so.. i did not make it on time