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Post by driventone on Dec 16, 2021 16:20:15 GMT -7
Background: after many years of Monza GAS, I finally decided this month that I wanted to move forward and buy a Monza with a PPIMV. Until recently, I didn’t realize that Dr. Z offers the mod on original Monza’s. I wanted a combo, but I found a head with a MV where the 4 ohm speaker output used to be. I sent Z a picture, and he and Don in repairs are all but certain they didn’t do the mod. Long story short, I found a non-MV Monza combo and it’s on its way To Z for the update. In the meantime, I’m not sure yet what I’m going to do with the Monza head. Before finding the combo, I planned on sending the head to Dr. Z to have the proper PPIMV mod and regular maintenance and checkup done. Curiosity has gotten the better of me, and I wanted to see what had been done to the head. In another thread (under Troubleshooting), I was having problems getting the back panel off. But I got in yesterday and dropped the chassis out this morning. There are some interesting things in here… pics to follow.
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Post by driventone on Dec 16, 2021 19:55:58 GMT -7
Let’s preface this next part with two declarations: 1. I am no amp tech. I have worked on amps a bit, but I am by no means in any position to criticize anyone’s work. 2. This amp does work perfectly, sounds great, and has zero issues. It is very quiet from a noise and interference perspective, and the MV works well and as expected. Now that that part is out of the way… Does this look like it was done right? For starters, there are 2 sets of 2 x 1 M Ohm resistors in series, and they appear a lot smaller than the resistors that are original (maybe a lower wattage?). Why not use 2 x 2 M Ohm resistors instead of 4 x 1 M Ohm resistors? I’m not crazy about the way it looks. The gauge on the wire going to the dual pot looks thinner than the factory wiring, and the dual pot itself looks a tad small. Also, kind of funny they just heat-shrinked the leftover wire from the 4 ohm tap from the OT. On that note, why is there only one wire (red one)? Again, I’m no amp tech, but when I replaced an output transformer in my Fender Champion 600, the new OT had 4 and 8 ohm taps, and I switch them out periodically if I want to run a different speaker. There are two wires for each impedance output. So, I was expecting to see two 8 ohm wires, connected to the 8-ohm jack, and two 4 ohm wires, heat-shrinked so they stay out of trouble (since the 4-ohm jack is gone). I didn't try to look at the output transformer itself to see what wires came from it, in retrospect I probably should have. Also, look at where the resistors are soldered to the turret… although functional and appearing to not be a cold joint, I think that could have been done better. I would have tried to wrap the leg of the resistor around the turret like Dr. Z suggests, then solder it. It’s safe to say Dr. Z did not do this mod. Again, I’m unsure what my plan is for this head since I have a combo coming from Dr. Z with the official mod.
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Post by bryan0418 on Dec 16, 2021 20:10:54 GMT -7
That doesn't look to me like a job the Z Shop would have done. The soldering doesn't look as good as they do. Also the Z shop marks their soldering after QC with a colored Sharpie so they can tell if someone has been inside the amp. Where the 2 resistors are in series looks to me that the red ink has been disturbed. The resistors look like they are lower wattage as well. Something Z typically doesn't do. I suspect someone else did the mod.
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Post by premiumplus (Dave) on Dec 17, 2021 13:04:30 GMT -7
Agree. That's not Z's work, no way.
See the black wire on the speaker jack? That would be the second wire from the OT for both the 4 and 8 ohm tap. Originally the amp may have had a wire running to the other speaker jack's ground connection but it's not uncommon for builders to just use the ground as a common connection between the two (or three) speaker jacks. I don't see a sharpie mark on the black wire to the speaker jack, so it may have been removed.
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Post by Don A on Dec 17, 2021 14:50:55 GMT -7
Wow! That looks nothing like the master that Dr. Z installed in my Monza! Besides the lack of quality, it's an entirely different setup.
On my amp, each grid leak resistor (220k?) was each replaced with a section of a dual gang pot (250k?) with a 2.2m resistor in parallel.
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Post by driventone on Dec 18, 2021 17:26:14 GMT -7
Wow! That looks nothing like the master that Dr. Z installed in my Monza! Besides the lack of quality, it's an entirely different setup.
On my amp, each grid leak resistor (220k?) was each replaced with a section of a dual gang pot (250k?) with a 2.2m resistor in parallel.
Yeah, this definitely wasn’t done by Z. Now I’m wondering what the sound difference would be if it were cleaned up and had the right resistors. As I said before, this amp sounds great, but to be fair, I have no frame of reference. The last time I played a Monza was on a non-MV 1x10 combo almost 9 years ago. Don A if you get a chance, would you mind please posting a chassis pic of your amp, so we can see what it looks like compared to this one? I have a Monza combo being modded by Dr. Z now. If I keep this head long enough, I might get a chance to A/B them (sonically) and compare.
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Post by Don A on Dec 18, 2021 19:11:13 GMT -7
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Post by helmi on Dec 19, 2021 8:02:26 GMT -7
That is pretty looking. so nice and neat.
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Post by Chilly Gibbons (Todd T.) on Dec 19, 2021 10:16:10 GMT -7
Yea, they are beautiful. This circuit in particular is a favorite of mine. Great high gain sound and as you can see, few components carefully chosen so that your guitar still sounds like your guitar under high gain.
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Post by driventone on Dec 19, 2021 11:35:05 GMT -7
Thank you for posting that. Wow, such a difference from my head’s chassis. If you didn’t know where to look, you wouldn’t even be able to tell that yours had been modified. It looks original - amazing. My combo chassis should look just like that when it gets to me, except with the dual pot on the front panel (I requested the new faceplate). It looks like they put the resistors on the back of your dual pot, whereas on mine they’re on the turrets. And of course mine has 4 lower wattage 1M Ohm resistors with each set in series(2 sets of 2M Ohms total), and yours is just two 2.2M Ohm resistors. I’m not going to keep this head. Funny though, I tried to justify it when you mentioned how much you like the three knob look. I agree - it looks better. So I was trying to convince myself to have a three knob head with the master on the back AND a 4-knob combo with the master on the front, but I really wouldn’t need both. Just going to keep the combo. I am beyond excited - I’ve wanted a Monza combo with the Red Fang forever. Guessing it should be here in 4-5 weeks.
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Post by Don A on Dec 19, 2021 13:21:47 GMT -7
I love my Monza, but I can't see having two of them. It's an amp that was designed for a very specific single purpose- to rock hard. I'd love to park a Carmen Ghia 1x10" combo beside it!
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Post by Chilly Gibbons (Todd T.) on Dec 19, 2021 15:26:29 GMT -7
It would be interesting to compare the two once you get yours back from Z. Who knows, you might find a reason to keep both.
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Post by driventone on Dec 19, 2021 17:30:29 GMT -7
It would be interesting to compare the two once you get yours back from Z. Who knows, you might find a reason to keep both. Stop enabling me please 😂 Would be pretty cool though… We’ll have to see how long it takes for the mod and for shipping. I’m not expecting the combo to arrive before the return period is up on the Monza head. I think I have another 3-4 weeks. Maybe it will come before then? This brings back bad/rough memories for me. When I bought my Marshall 4010 combo, I ended up with an ‘82 that was beyond trashed, and an ‘83 that is dead mint. I knew I had to keep the ‘83 because it’s the year I was born, and because it is nearly collector grade. But the ‘82 sounded way smoother and sweeter, while the ‘83 was aggressive and harsh. I ended up taking both to my amp tech, and he went through each to find differences in the circuit. (Long story short, there had been small mod on the ‘83 that he undid. Took a while to find. There were also some resistors that he changed to match the earlier 2204/4010 circuit.) It was a serious pain. In the end I guess it worked out; I got to have a very clean and great condition amp, and my tech had access to a direct template for matching and improving the tone. Either way, with the Monza, if I kept the head, I would definitely send it to Dr. Z for the proper mod, checkup, etc. Not sure I’ll have the appetite for that, after paying for shipping the combo from NJ to Dr. Z, getting the mod and checkup on that one, and then shipping it to me in California. I’m almost certain in this instance that the combo is going to be everything I could want Monza-wise. Now what do I do about this curiosity I have growing for the Maz 8 and a Carmen Ghia? I feel GAS coming back on…
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Post by driventone on Dec 19, 2021 18:03:21 GMT -7
Yea, they are beautiful. This circuit in particular is a favorite of mine. Great high gain sound and as you can see, few components carefully chosen so that your guitar still sounds like your guitar under high gain. This - 100%. I’m still getting to know the Monza, and Dr. Z amps in general, but I’ve had this experience already. My ‘79 Les Paul with T-Tops that weighs 10+ lbs sounds a lot different than my G0/R0 historic (based on the one from BOTB in my avatar) with Burstbuckers. They’re very different animals. The G0 has an almost semi-hollow quality to it, where the ‘79 is very solid. On my other gainy amps, both guitars sound really similar at high gain. But on the Monza, I can still clearly hear the character of the G0. It still sounds sweet and dynamic, even when going through the overdriven amp. I thought it was cool that you brought this up, since I just had that experience with it.
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Post by Don A on Dec 19, 2021 20:10:02 GMT -7
It would be interesting to compare the two once you get yours back from Z. Who knows, you might find a reason to keep both. This brings back bad/rough memories for me. When I bought my Marshall 4010 combo, I ended up with an ‘82 that was beyond trashed, and an ‘83 that is dead mint. I knew I had to keep the ‘83 because it’s the year I was born, and because it is nearly collector grade. But the ‘82 sounded way smoother and sweeter, while the ‘83 was aggressive and harsh. I ended up taking both to my amp tech, and he went through each to find differences in the circuit. (Long story short, there had been small mod on the ‘83 that he undid. Took a while to find. There were also some resistors that he changed to match the earlier 2204/4010 circuit.) It was a serious pain. In the end I guess it worked out; I got to have a very clean and great condition amp, and my tech had access to a direct template for matching and improving the tone.
Do you still have the Marshall 4010? I have an '82. Marshall changed the power transformers in them during that year and raised the B+ voltage by about 100 volts. Mine has the lower voltage PT. It's a great blues rock amp. I use it for similar styles that I use the Monza for. I'm interested in knowing how you think they compare.
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Post by driventone on Dec 22, 2021 19:49:42 GMT -7
This brings back bad/rough memories for me. When I bought my Marshall 4010 combo, I ended up with an ‘82 that was beyond trashed, and an ‘83 that is dead mint. I knew I had to keep the ‘83 because it’s the year I was born, and because it is nearly collector grade. But the ‘82 sounded way smoother and sweeter, while the ‘83 was aggressive and harsh. I ended up taking both to my amp tech, and he went through each to find differences in the circuit. (Long story short, there had been small mod on the ‘83 that he undid. Took a while to find. There were also some resistors that he changed to match the earlier 2204/4010 circuit.) It was a serious pain. In the end I guess it worked out; I got to have a very clean and great condition amp, and my tech had access to a direct template for matching and improving the tone.
Do you still have the Marshall 4010? I have an '82. Marshall changed the power transformers in them during that year and raised the B+ voltage by about 100 volts. Mine has the lower voltage PT. It's a great blues rock amp. I use it for similar styles that I use the Monza for. I'm interested in knowing how you think they compare.
Funny you should ask… check out my current rig setup in the pic attached. I don’t have a cab right now, so I’m using the G12-65 from the 4010 for the speaker for the Monza. A byproduct of this is I get a direct comparison between the two amps with the same speaker and cab. I’ll post a tone comparison thread under the Monza section - this thread about the PPIMV is resolved. Thanks again for posting your chassis shot! Very helpful info, glad we documented it.
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Post by driventone on Feb 13, 2022 11:42:06 GMT -7
It would be interesting to compare the two once you get yours back from Z. Who knows, you might find a reason to keep both. It’s been a few weeks since the Monza head left, but my combo is here now. Don at Dr. Z put in 6n14n’s instead of the EL84’s, so I’m sure that adds a bit to the difference in sound, but I’m happy to say this one sounds really similar to the Monza head I had. To me, this means that Z amps are really consistent. (Even though the head had been modified by someone else.) I recall the Doc saying in an AMA video that he is very selective of components to make sure amps of the same model all sound the same. If I had to put my finger on one difference between the two amps, I would say this combo has a little less top end fizz, which is perfect. It’s not a big difference, but I’m finding that I don’t have to tweak the tone knob to take out any fizz on this one. I don’t know if that’s a function of the 6n14n tubes (especially since I’m playing at low volumes and they’re likely not being driven hard), or a difference in the two PPIMV mods, but I’m very happy with the combo.
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Post by LT on Feb 13, 2022 13:33:55 GMT -7
Do you still have the Marshall 4010? I have an '82. Marshall changed the power transformers in them during that year and raised the B+ voltage by about 100 volts. Mine has the lower voltage PT. It's a great blues rock amp. I use it for similar styles that I use the Monza for. I'm interested in knowing how you think they compare.
Funny you should ask… check out my current rig setup in the pic attached. I don’t have a cab right now, so I’m using the G12-65 from the 4010 for the speaker for the Monza. A byproduct of this is I get a direct comparison between the two amps with the same speaker and cab. I’ll post a tone comparison thread under the Monza section - this thread about the PPIMV is resolved. Thanks again for posting your chassis shot! Very helpful info, glad we documented it. Add me to the guys that owned a 4010. I also had the matching 1-12 extension cab. Fun amp. Yours looks like new! I sold mine back in 1988 when I moved from St Louis. Wish I would have kept it!
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Post by Don A on Feb 13, 2022 14:40:43 GMT -7
It would be interesting to compare the two once you get yours back from Z. Who knows, you might find a reason to keep both. If I had to put my finger on one difference between the two amps, I would say this combo has a little less top end fizz, which is perfect. It’s not a big difference, but I’m finding that I don’t have to tweak the tone knob to take out any fizz on this one. I don’t know if that’s a function of the 6n14n tubes (especially since I’m playing at low volumes and they’re likely not being driven hard), or a difference in the two PPIMV mods, but I’m very happy with the combo. It's probably a difference in the PPIMVs. My Monza has JJ EL84s in it and it's incapable of producing a sound that could be described as top end fizz.
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Post by driventone on Feb 14, 2022 16:30:55 GMT -7
If I had to put my finger on one difference between the two amps, I would say this combo has a little less top end fizz, which is perfect. It’s not a big difference, but I’m finding that I don’t have to tweak the tone knob to take out any fizz on this one. I don’t know if that’s a function of the 6n14n tubes (especially since I’m playing at low volumes and they’re likely not being driven hard), or a difference in the two PPIMV mods, but I’m very happy with the combo. It's probably a difference in the PPIMVs. My Monza has JJ EL84s in it and it's incapable of producing a sound that could be described as top end fizz. I know sound can be really subjective, so to clarify what I was hearing, it reminded me of having the presence knob on a Marshall turned up a bit too high. Good news was, turning the tone knob down always seemed to fix it. I’ve never had an EL84 amp, and that was the only Monza I was able to crank the volume on, so I wasn’t sure if that was just how EL84’s sounded. I should have known that’s not the case - I’ve seen Frankie Starr and Dave Baker’s Monza demos enough times to know! I agree about it probably being a difference in the MV mod. I keep looking back at the pictures of the old head, the pictures you posted of your Dr. Z modded chassis, and now looking at my Dr. Z modded chassis - the old head was really different. Especially the 4x 1M Ohm resistors on the turret board, connected to the dual pot. I don’t seem to see those in the official Z mod circuit at all. Yeah, something wasn’t quite right on that one. Sounded good enough, but the new one sounds better. Hopefully the new owner sends it to Z one day and they straighten it out. I saw on the GC site that it sold in like 2 days. Even if they keep it as is, still sounds good.
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