The 40' cord used on my CD was about 3500pf! That said these days that cord sounds too muddy for me.
Sure it's not your high frequency hearing heading south? Those damn things are loud and want to be played that way.
Keep in mind that old cord I was referencing had as much capacitance as SIX Mogami 18' cords in series!
Most folks would probably think that a cord with 3500pf of loading would be WAY to dark with most amps, but it worked with the Express and bright studio mics like an SM57. But these days I find that cord to be a little too dark and it's capacitance was so extreme it had a mild upper mid spike. Still for some leads it really sang with that cable. These days I prefer the two Mogamis and just moving the mics around if it needs any more taming. I might only use one short cable for clean work, but once the amp is pushed hard I've almost always found it too bright in the extreme top end with just one short cable. I've also tried one cord and running the bright switch off, but it just doesn't work for me.
These days I "just" use two Mogami 18' cables in series (about 1200pf) then set all the knobs on my Express at 1/2 with the bright switch in the full position, then my typical mics are a combination of a Sennheiser 421 mixed with a Royer 121.
That's what I was thinking. Let the preamp create its magic as God, er, Ken intended it to. If you need to cut the highs to make it work with the speaker(s) you are using, then I would try doing that after the PI w/ some variety of the AC-30 cut control.
Of course if the preamp magic isn't happening then you might have to do some tweaking of the preamp tubes and component values.
I also agree with the suggestion to try adjusting the controls on the guitar and the amp. I think I played guitar for at least 30 years before turning back the tone control on my guitar... Am I supposed to adjust that? I thought it was there just for looks!
Can't wait to get back home and tweak the amps this weekend! I'm thinking I'll mess around with the input attenuation and maximize signal while ensuring getting rid of any parasitic microphonics....probably 10k to 33k range.
I'm going to throw in pink noise signal into the amp and measure and see how the frequencies respond with the spectrum analyzer. I think my approach will just be to tweak the tone stack and cut the dB's at certain frequency to taste....therefore if the spectrum analyzer shows a spike at 1k, I'll tweak the tone stack to cut 1k without affecting too many frequencies outside of that. The player can determine if they want to leave as-is, or cut back on the frequency(s)! Wink
Generally speaking and looking over and doing some calculations with the Tone Stack calculator, I like how the Fender stack really impacts the frequencies, but there seems to be a lot of loss to overall signal.
To maximize signal and still get a good flat and yet responsive controls, the following looks like a good mix - change R4 from 100k to 33k, R2 from 1M-A to 250k-A and R4 from 250k-B to 100k-B. The signal seems maximized and flat 20-20kHz with the dials at B-10, M-10, T-2 which is where I'd like to be...maximize signal and flat all dials at 10 and attenuate back! With these valuse, bass cut is about 10dB, mid cut is 15dB, and treble is about 3dB w/ reshape of the curve. -17dB at 1kHz.
Since I don't like the bright switch as it's radiculously bright with it on, it'll probably go away, take it out and just use a standard 470pF from VR4P1 to ground.
That's about it for now. I'll post clips this weekend. Maybe should start a different thread as this one was oiginally about transformers! p.s. - the Magnetic components are great and no issues!
Are you saying your build has Mercury Magnetic transformers? I've definately heard from more than one source some of their transformers run on the bright side. Could be your OT right there causing the upward tilt in tonality.
Ok, just got in from Mexico all week and ran some values on the plane. I REALLY like what I'm seeing in these values (below). It's mid is focused on 1k and when the settings are adjusted you can get flat or the right to left waterfall that say Marshall gets!! Soo, it's pretty versatile.
Attached are the overall range, bass range, mid range, and treble ranges!
According to the '90' Kelly schematic, the following components would deviate from the schematic:
C5=220pF
R4=33k
C3=47nF
VR1=250k-A
VR3=100k-B
Robb
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Not trying to discourage you in your experimenting. Thats fun to do and is a learning experience to fine tune an amp to your liking.
Just wanted to say that sometimes the graphs or charts leave out the human factor of how it sounds to the ear,or how the amp reacts to ones playing, the bloom or interaction of feedback ,down to the speaker and guitar that is used.
Hopefully it will turn out like you are wanting it to.
Sometimes it doesn't. No big deal, then that gives you a reason to try other things.. Keep posting how it turns out.
yep and understood. That's the reason why I wanted to move the knobs and at least get the same curve as you'd get from TW or Marshall...yep, I was able to achieve it in theory...with more gain! Soo, it should be cool!...but we'll see!
Glen, to you mainly, you are saying that the original Express is just too bright/trebly out of the gate to use for one of your very toneful solo/lead guitar sections within your recordings - and that you have to tame this brightness with your cable length/brand choices. I think I have stated this correctly, as long winded as that reads.
OK, if this is true, (or to anyone else who has another original Express), may I ask you to give us a sound sample of the amp without the use of the special cables? I could imagine a very simple soundbite would work, with recording in progress. First with the guitar into the amp using a short cable and then with the short cable swapped out with the longer cable? (Ten quarter notes, a few bars, would do it for me I think.)
(And now that I think about it, Glen, is there a section in one of you songs where you do use a short cable? Maybe some rythm work?)
Well, you can see what I'm after I hope. I for one think it would be a good idea to just have the very basic sound of the original amp documented. Especially when I hear about the use of longer cables to tame some of the treble.
(Has this been done, original Express recorded while plugged into with a typical 10' Spectraflex cable? If it has, please point me in the direction of it please.) Thanks in advance, Glen, if you can find the time and energy to do this.
Most people stall out when fixing a mistake that they've made. Why?
Keep in mind x2 Mogami Gold 18' scords is not a night and day amount of high end roll off, but it is noticable in the range above about 4k or so. It just rounds out the very extreme top end. My old 40' cable I used on my CD was way more dramatic, but most of my Youtube clips are with my two Mogamis. Still, this isn't something out of the ordinary in my thinking. Typically when I do a club gig with say a Fender combo amp and a pedal board I'm still using the two 18' Mogamis, one from the amp to the pedal board, and the other to the guitar. On most stages it takes this kind of cord length, and when I started doing this with a wreck it was just something I had always done before with old Marshalls and such. Only later did I realize the tonal changes the cords had, and with both my old Plexi 100 and the wrecks the highs needed a bit of taming. The cords surely do not cut as much highs as say the bright switch adds back in, it's actually much more subtle than that. In other words the cords surely don't cancel out the bright switch effect, they just tame the 4-10k range of shrillness and fizz. Still, the high end roll off of the cords is hard to simulate with the tone controls on the amp as the treble and presense are just at lower frequencies. However I bet with experimentation you could come up with a cut control that would do a similar thing as the cords. On a side note the Express/Liverpool can have so much gain that with alot of guitars you simply need a long cord to keep the guitar from feeding back unless you go with potted pickups. I'll also mention when recording the amp going from say a Shure SM57 to a Royer 121 ribbon has WAY more of a darkening effect than the cord trick...
I should still mention that for some reason just about all of the wreck clones I've played were brighter than the original wrecks I've played/owned. The kind of brightness that is hard to dail out with the amp knobs. I'm not sure why this is a pretty consistent trait among "clones", but in my experience has seemed quite the norm.
Hey guys a few things since I got back from Mexico on this thread and don't see I mentioned...
1. There was a whistling with the presence and i had a few ideas what might be causing it. The first thing I tried...metal (aluminum cover on the bottom to keep out RF and cover the bottom with ground. PROBLEM SOLVED! Also with this, this may seem weird, but maybe the NFB is working better, but the amp doesn't seem as bright!! It's still tonally voiced in the mid-range to cut through the mix, but doesn't appear to be as bright with all settings the same!! I thought I'd share.
2. I'm happy with the tonestack and more now, but I will still take sound clips and try my different settings as it seems to accomplish targets I want more than the original. I will take sounds clips of the alternative tone stacking and also, I'm just using 6V6's (JJ's). I'd like to try EL34's and take some sound clips also.
Stay tuned. It may be until the weekend as I haven't been recording and using my software as much, so I'll learn it, then not use it for 6 months, then forget it again!
It will also probably be a little darker with EL34s vs the 6V6s, maybe a hair louder but probably not as cutting. That said the JJ 6V6 will mellow a bit over time, and I like them in my small Fenders ('64 Deluxe & '83 Champ II) once they have some time on them. Still there is a sweetness with having EL34s in the wreck that isn't there with the smaller tubes. Perhaps the slightly higher wattage saturates the OT enough to round off the top just a tad more.
Wow, 1 year and and crap load of amps later and I'm back into this!
I never did get around to check out the tone stack, but getting ready to R&D it! I hope it's a winner as the TSC shows!
I ended up keeping the Express stock after all this time! Bright switch stayed in and only check out the difference between JJ 6V6's ansd EL34's.
The 6V6's are lower wattage and more modern sounding...cleaner and tighter. I'm from the 80's thou, soo used to the EL34 sound and seemed less bright and tight/clean and add that traditional fizz to the top end, so that's the way it's sat...and I'm very happy with it.
I wish there was a way to tone down the volume, but I think we all know one of the majic's about it is the early breakup of the outputs. PPIMV and other things will/may inhibit that, so you're left with loud or attenuator. I use the TW Air Brake to attenuate it, fyi.
I did a couple of things with mine when I built it and have learned a few tricks for controlling it. I changed out my bright caps with polystyrene caps of slightly smaller values and that seemed to smooth things a bit. I ran 6V6 power tubes in mine for over a year, but it really doesn't drop the volume down that much and you lose a bit of the cleans. Don't get me wrong, I still like it, but the EL34s have a better clean to mean range in my amp.
The other thing I have done is to modify my playing technique. Over the last couple of years since I built my Express, I have become intimately familiar with my volume control on the guitar. Having the treble roll off a bit with the volume is a great advantage and getting the treble back for solos when you wind out the volume really punches through the mix. Between backing off of the volume, palm muting and playing dynamics, you can take a great deal of brightness off of the amp. I am so used to rolling the volume control around now, I can gig without my pedal board and not miss it at all. Who needs a channel switcher when you have infinite possibilities right at your fingertips?
Those damn things are loud and want to be played that way.
If you need to cut the highs to make it work with the speaker(s) you are using, then I would try doing that after the PI w/ some variety of the AC-30 cut control.
