The small change between 10 and 6 is because of the linear taper. Audio will give a wider range of control. The safety resistors can be chosen to set the resistance at 10 back to 220K.
I guess I'm confused, I've always associated audio taper with a huge change from 10 to 7 and then very little after that. This almost seems to be behaving like a reverse audio taper. I always viewed linear as.. well linear or much more linear through the range. I obviously haven't experimented enough myself! Thanks Lyle
@@YeatzeeGuitar Audio tapers ramp up faster the more you turn them. The % rating/taper is measured at half of the turn/sweep. So, a 1 Meg J taper (30%) would measure ~300k at the half way point. After the half way point, all audio pots rapidly turn into a linear taper pot. The "A" (10%)taper is good if you want fine control of the bottom end of the sweep. The Alpha dual gang 250k Audio is an A taper I believe. Vintage Gibson Les Paul's from the 50's shipped with 10% A taper CentraLab pots. Very good control for humbucker.
LarMar’s work great in Fender amps. Your recordings prove that. An audio taper pot would be a little easier to dial in at lower settings. I don’t see a need to change it unless you’re bored some night. Great job btw!
I think it fairs a bit better in the recording vs in real life, but there's no denying it really retains the tone pretty well. It just has such little smooth transition from way too loud still to just right. It's honestly more just to have in case I absolutely need it, vs any real plans to use it much... we'll see what I decide to do! Thanks man!
I have the same values on my '71 DR but audio taper. Very smooth range. Don't get too influenced by the measured resistance values at different settings since this is a divider and we don’t hear in a linear fashion. I used shielded wires for each path with the bias on the shield(s.) Could use a double conductor + shield/bias for less wires but not vintage looking. You probably don’t need shielding since the pot is near the output tubes already while mine is next to the regular volume control (in hole for input #2.) Twisting helps of course. Sound on 10 should be exactly the same as with no master since the schematic is identical at that setting. Only noise should be a possible factor. Lar mar allows for (more) phase inverter distortion with no/less output tube distortion and volume. It should sound somewhat different than an attenuator which allows for all the normal amounts of both distortions. I have to reduce the bass if using very strong channel volume. I like the channel on ~7 for distorted tones. Sometimes I’ll attend a jam with zero pedals having 3 effects now built in.
Linears can work as guitar volume pots but almost never in amp gain stages. An audio taper MV will widen the sweep so it's not all bunched up between 3 to 1
Don't want to just restate what I said to Lyle's comment, but yeah I'll give an audio taper a try. I went with linear to have a more linear response through the range... what I associate with audio taper is more how this is behaving to me but I just need to test audio and see 🤷♂
@@YeatzeeGuitar Wire the existing linear backwards and see what the sweep is like. You might need a knob with a pointer rather than numbers, if you like it... 😶
@@YeatzeeGuitar Yes, to understand why you should have used audio (AKA logarithmic) pot, you need to understand that human hearing perceives changes in volume logarithmically. Therefore, the audio taper pots were invented to match the logarithmic curve representing our hearing sensitivity (i.e. you need it to be an audio taper pot for it to be perceived as behaving linearly).
I have a late 1964 black panel Bandmaster, and I'd really like to add a master volume, but it seems like sacrilege. I bought a 2 Notes Captor 4 ohm thinking the -20 db would work, but it was too much attenuation.
Nice! Just have a tech follow the steps I show in this video and they can easily add a master volume (assuming they don't know how to already). No added holes required!
Love the video, i do like the audio taper vs. linear for this, so I agree it might be worth comparing. For playing bar gigs, I do like running my preamp gain/volume around 6 to 7, then adjusting the PPIMV for venue, then tweek the tone control as needed. I haven't tried the powerstation, but I do prefer this setup to other attenuators I've used in the past. (Of course, it's all personal perferance, really) Have really enjoyed the super series. I look forward to the next video
Yeah I think I'll just pony up and buy one to compare. I was really impressed by the powerstation with the Super Reverb, it sounds great but it definitely changes the tone more than it does with other amps. It's not a bad change in the tone though... at least imo.
Nice job. Looks like a LarMar. One small critique... You never actually checked the bias voltage on the grid (pin5). You checked on pin 1 but there is still a 1.5K before you get to the grid. I've never seen one of those 1.5Ks fail but I'm sure Murphy has. My point, check the bias voltage directly on the grid (pin 5).
Thanks! Yeah your right, that would have been better. I had just replaced them and already tested to make sure they were good before installing the MV but best practice totally.
Nice work. One note of caution. The multimeter clip on probes look like the ones I have, and over time the wires have started to pull out of the plunger part of the probes, exposing copper wire. I've glued them in place for now, but probably need a higher quality set of probes.
@@YeatzeeGuitar I always use the one hand method when working on a live amp, but you can never be too careful, so the exposed copper wire had me worried. I think I will look for some heavier gauge wire clip on probes that are also longer than 2 1/2 inches that my current ones are.
@@YeatzeeGuitar Will do. I also noticed that the "hook" on the end of my inexpensive clips have straightened out over time. I was able to re-form the hook with a couple of pairs of small needle nose pliers, but I was lucky I didn't break them in the process.
Good job but maybe its just me - I think there is a slightly noticeable difference in the basic clean Before / After at full volume (=10). Before is fuller, deeper, chimier; After is more nasal/ midrangey. If you really need the master to reduce absolute volume, then fine. But there is a cost to the basic sound
Hmm, I don't remember hearing much but I'll have to listen back. As shown I think in the next video in the series I believe, the values were not exactly stock at 10 and I redid the MV with a different pot that got basically dead on.
Post phase inverter master volumes in fender amps sound better with a 12AX7 tube in the phase inverter socket. Overdriven 12AT7 phase inverters can sound splatty, due to the characteristics of the 12AT7.
It was recommended to me not to put the MV pot near the HV/AC currents. I think if you leave it there you should at least avoid running the signal wires in parallel with the AC hot wire. I would go straight to the pot and cross the hot wire at a 90°. That and I would probably use shielded cable. I don't know that I heard any noise problems though so maybe it's a moot point.
Love your videos! Why not try an audio taper pot instead of a linear one? As Psionic has stated you’ll get a wider range of control out of the master volume. I’ve installed audio taper pots in my Fender Jagmaster to get a wider range of volume and it sounds very nice and even.
Thanks! Think I'll need to give it a try and see! I've used linear on others and they worked better, I do think this particular pot's sweep is a bit funky.
Too much time between them to really say anything. It does seem like there's a very slight difference at times, but other times it sounds identical. Hard to say, but it's slight either way
One comment I have, more of a question, is what is the affect of changing the output coupling cap values? I haven't watched much about Super Reverbs but a lot of the info I am seeing for the Bassman (AB165 particularly) shows changing the output coupling caps from 0.022 uF to 0.1 uF (and sometimes swapping those .022s with the blue molded .1s that are connected to the BASS channel bass pot to 'tweed' that channel.) I noticed your SR has 0.047 uF blue molded caps. I wonder what affect to tone or response, if any, changing those would make.
