NAD! '82 Marshall 4104 with EV's

[VonBonfire]

I didn't get around to posting this earlier, but here is the spectral analysis of the three tracks from above. An interesting note related to your comment, @VonBonfire, is that they all have a scoop around 750Hz.
View attachment 389249

So is it the speaker? Amp and/or amp EQ? Both? I mean, you have the mids dimed. I know a Twin is def scooped and I dial out all the mids as a matter of routine otherwise it'll get muddy at high volume but it does tend to thin out leads a bit so anything but higher, biting notes have a bit of hollowness to them in a similar sort of manner. Makes me wonder if it's not something with the Force 12's. Maybe a TS boosting it would help correct it.

 

[7704A]

So is it the speaker?

No idea yet. The graph just shows what is in the track, I haven't measured the speakers by themselves. I did do some quick math though, and the wavelength for 750Hz is about 17.3". That's pretty close to the distance my amp is from the wall, and I have the amp square to the wall. My first thought is "Oh, that means that there is a node roughly at the wall, so there is less sound of that frequency being picked up by the mic." However, the mic I'm using senses air pressure not air movement if I remember correctly, so I don't think the wall should be causing any problems since the pressure at the wall still tracks properly. Should be easy to test though, just move the amp and see if the scoop moves.

 

[VonBonfire]

No idea yet. The graph just shows what is in the track, I haven't measured the speakers by themselves. I did do some quick math though, and the wavelength for 750Hz is about 17.3". That's pretty close to the distance my amp is from the wall, and I have the amp square to the wall. My first thought is "Oh, that means that there is a node roughly at the wall, so there is less sound of that frequency being picked up by the mic." However, the mic I'm using senses air pressure not air movement if I remember correctly, so I don't think the wall should be causing any problems since the pressure at the wall still tracks properly. Should be easy to test though, just move the amp and see if the scoop moves.

When you get your 57 maybe you can get five or six feet clear in front of the amp to open things up and try things then. 17" is pretty close to the wall but by the same token plenty of guys put plexiglass or guitar cases in front of their amps about that distance and it doesn't seem to be a problem. I do that sometimes if I have people seated directly in front of the amp from a raised stage. I call those the "combat seats" LOL.

Also interested to know how much space behind the amp you have also and what material is behind it. IME with open backs there can be some added harsh tones if the back is close to a wall, especially a wall with metal, stone, or glass and the ceiling is 8ft or less. If you are on a hard floor that will also add to harsh tones. I put a rug out in front of the amp in those situations to mitigate the hard surface "slap". Anyways, just a couple ideas to think about.

 

[7704A]

Also interested to know how much space behind the amp you have also and what material is behind it. IME with open backs there can be some added harsh tones if the back is close to a wall, especially a wall with metal, stone, or glass and the ceiling is 8ft or less. If you are on a hard floor that will also add to harsh tones. I put a rug out in front of the amp in those situations to mitigate the hard surface "slap". Anyways, just a couple ideas to think about.

8ft of basically empty space until the next wall, ceiling is around 8-9ft, carpeted floor.

 

[7704A]

@VonBonfire just thought of something else. My 4104 still has the "mids cap", which is supposedly there to compensate for the 2x12 format by reducing mids, so that's something else for me to look into regarding the scoop.

Edit: here is Johan Segeborn demoing his 1x12 combo with/without the cap.

 

[VonBonfire]

@VonBonfire just thought of something else. My 4104 still has the "mids cap", which is supposedly there to compensate for the 2x12 format by reducing mids, so that's something else for me to look into regarding the scoop.

Edit: here is Johan Segeborn demoing his 1x12 combo with/without the cap.

I'll give that a good listen tomorrow when I can crank it up properly. Catch you then!

 

[Erock]

Congrats on the score man!

I like the boosted clips, but of course, I love boosting.

Short-term update for others with a similar issue: the JB Weld KwikWood is holding well. Today I took out the screw to add a washer under it (there was still some play in the baffle with the screw bottomed out) and it took some effort to back it out by hand. There was some JB Weld stuck in between the threads, but after cleaning that out a bit and sticking the washer on I was able to put the screw back in and crank it down by hand without stripping the hole. With the washer there is now no play in the baffle related to the screw. I use the cabinet as an office chair, so we'll see if any develops over time.

If you do have issues, I've had some good luck with sawdust and wood glue. I used some toothpicks along with it to add some solid wood. None of the stripped holes I've fixed that way have come loose.

 

[7704A]

Congrats on the score man!

I like the boosted clips, but of course, I love boosting.


If you do have issues, I've had some good luck with sawdust and wood glue. I used some toothpicks along with it to add some solid wood. None of the stripped holes I've fixed that way have come loose.

Thanks! So far the screw is holding, but if it doesn't I know something else to try now before going full dowl-in-hole. Agreed that boosting is great.

 

[7704A]

I'll give that a good listen tomorrow when I can crank it up properly. Catch you then!

I just popped the audio from the video into my DAW to check the spectrum, and I'm not seeing the scoop appear or disappear with the cap. So possibly not that.

Spectrum comparison for one point in the video that sounded super noticeable:

 

[VonBonfire]

@VonBonfire just thought of something else. My 4104 still has the "mids cap", which is supposedly there to compensate for the 2x12 format by reducing mids, so that's something else for me to look into regarding the scoop.

Edit: here is Johan Segeborn demoing his 1x12 combo with/without the cap.

Both sounded pretty good to me, no cap seemed brighter, but they also both sound kinda boxy. Unrelated to the discussion I guess but that's why I like open back 2x12's. Unless you have a spacious 1x12 cab, such as a deluxe reverb, those compact 1x12 combos usually sound enclosed like that to me.

I just popped the audio from the video into my DAW to check the spectrum, and I'm not seeing the scoop appear or disappear with the cap. So possibly not that.

I think you're right, I doubt it's that cap. I'd await further judgement for when you have a 57 in hand to do some checking.

 

[7704A]

I just double-checked some physics, and it doesn't look like it's the microphone/wall situation. Short story is that with soundwaves, the places where air stands still because of standing waves is where the pressure changes the most due to the sound. So the fact that I expect the air to stand still at the wall's surface, or thereabouts, should not affect my microphone since my microphone detects pressure. I'll still try moving around the amp to test that though.

 

[7704A]

'57 is in the mail.

 

[7704A]

Messed around some more, and tweaking the EQ seems to have knocked out the hollow and fried quality to the sound. Possibly mic placement too? Clips will follow.