I was in the process of replying to a request for info about a tube chart and the thread had disappeared. The OP was talking about modding his to change the bass response, has that upset someone?
Anyway my reply was:------
MIne has a tube chart glued to the inside of the shell, but I can't tell you for definite what it says as its away at my tech having external bias adjustment fitted. I think its as follows V1 12ax7 V2 12at7 reverb driver v3 12ax7 reverb recovery V4 12at7 PI V5 6L6 V6 6L6
Be interested in your valve swap experiences since I find mine a bit lacking in sparkle/chime also. I had tried one prior to finding mine second hand and am finding it quite different to the first one I tried (Matt Schofields brand new one) I think my reverb driver might be on the way out since when i turn the reverb mix past about 12:00 it starts to get quieter.
I'm hoping a rebias will sort out the lack of sparkle but failing that I'll try valve swapping in the pre-amp then a new set of output valves
That was mine. I deleted it myself. After 37 views and not a single response, I was concerned (perhaps wrongly) that my having expressed reservations on aspects of the amp's performance had turned the reviewers off. But as long as you've responded (and thanks much - I got a near instantaneous response on The Gear Page that exactly parallels yours), I would add that I, too, find the EZG-50, despite it's many other areas of excellence, lacking in what I'd call the trad Fender blackface sparkle.
I believe it's the lack of a bright cap ("treble bleed cap") on one of the volume controls. I read a very early thread here where someone else asked about that and one of the moderators replied that he tested some caps on his amp and "it doesn't need it." But I really think that depends totally on the guitars, cabs, and speakers you're using ... which is why many, if not most, BF circuit amps are built stock with bright switches that can be turned on and off as desired.
Personally, I can hear the missing cap and will likely experiment soon with one for my own amp, beginning with a 33 pf cap (which will add a very small amount of extra highs), followed (if necessary) by a 50, 64, or even 100 pf cap.
In fact, the top end tone of my new/old EZG-50, right now in terms of presence/sparkle (or lack thereof), reminds me of my Tone King Continental with no cap. Adding a 33 pf cap to the circuit made all the difference in the world, with that amp, in terms of adding in those frequencies we typically call presence/sparkle.
I believe this will make more of a difference to the amp than any V1 tube swap. Though if you or I choose to try that, most folks seem to recommend the older square-getter Chinese 12AX7s which tend to sound a bit on the thin side (but that may be a plus with this amp) but have a lot of high end presence (also a good thing with this amp).
Hope this helps and thanks again for responding to my question that I'd deleted.
I too found my initial posts went unanswered for what seemed like ages.
Bright cap might well be worth a try, but to be honest I'm more concerned that my amp sounds so very different to the more recent one I tried. I want to know why and it doesn't help not having a schematic. I bet there have been minor circuit/component changes since the amp was first introduced (I have an early one it seems) and it very difficult to know how to get 'that' tone that I heard when I demo'd it.
One, there is a huge - more than most people appreciate - psychoacoustical element to hearing. That's fancy for your mood, how tired you are, etc. colors how your brain interprets the electrical energy (firing neurons) that = "hearing."
Two, *where* did you hear the first amp? The room, its size, contents, etc., also makes a huge difference.
Three, there's the spec limits of the amp's parts. Parts are normally considered "in spec" if they fit within the manufacturer's predetermined range. But that range can vary. Component specs can also drift over time.
But as far as your amp's circuit goes, I haven't yet pulled my chassis but a friend who also has an EZG-50 who pulled his told me it looks to be your classic Fender BF tone stack. I.e., it'll be simple to decode and simple to mod.
And FWIW, I believe I also have an early one (the 9" height version).
In my earlier deleted posts, I mentioned that the same friend told me the value on the mid control is 10K. Upping that to 25K will significantly increase the mid control's range.
This also from scottl on The Gear Page:
Fender used 22uf bypass caps on the cathodes of their gain stages. Dumble reduced this to 4.7uf (on most but not all ODS amps) as a matter of comparison. If you do this, you reduce the bass energy as the bypass cap size creates a shelving filter with up to -6b of attenuation. You can go lower.... Marshall I believe used .68uf?? Lower = less bass.
The coupling caps create a filter as well. Suppose you have a .05uf cap connected to the plate of the V1 output stage. If you reduce this, you lower bass content. This is my preferred method of tuning. Over changing bypass caps for instance. Both do work well though.
Post by frankiestarr on Mar 25, 2011 13:17:44 GMT -7
Ummmm.....It's defiantly not Fender Twin bright, but I could see kicking up the first or second sliders on my stomp box EQ to get that bright cap effect...Just a thought. Or maube some tighter brighter speakers. Just a thought.
Post by thecryingstrat on Mar 26, 2011 10:31:51 GMT -7
it´s amazing how different we perceive sound or even how can units may vary.... i would never say my ezg50 lacks sparkle! i even think it´s very bright and sparkly in a good way. Never used my treble knob higher than 11 oclock!
slaming the heck out of an EZG 50 and MAZ 18 NR!!!!
Post by jimmysmith on Mar 28, 2011 17:22:01 GMT -7
well , i can only say, the one i had, with stock tubes and through a 2/10 cab with a TELE had all the sparkle and highs i could ever want. and i never dimed the treble , i also used a 4/10 cab with it, maybe the 10 inch z spkrs can make a difference.... it does not sound just like my 71 twin reverb, but the low end on it blows my twin out of the water, and i had to turn the bass almost off.. with single coil guitars i never had a bad treble experience with that amp, i traded it for a kt45 cause i dont use reverb much, and just like el34 tubes , the kt45 can still sound like a fender,,,
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