Tweaking answers - Part 1 - the input

[heisthl]

The input - A 1meg(preferrably a 1 watt metal film) from the tip to ground at the input jack with the shorting contact (NC) at ground. The tip has a shielded lead to a 22K resistor connected to the grid of the first stage. The shield can be grounded at the jack or near the tube but not both. The 22K vaule can be raised to 47k or 68K and the 1M to ground can be reduced to 470K but the "real values" are 22K and 1M. The tube plate/cathode values can be 100k/1k5, 120k/1k8, 150k/2k2, 180k/2k7 or 220k/3k3. The bypass cap is generally 5uf with values up to 25uf on the 100k plate option. The older "real" values were 100k/1k5 and the newer "real" values are 220k/3k3. Rule of thumb, larger plate/cathodes = cleaner.
(from Dogerars: Higher plates add a lot of low end to the tone. The plate is in parallel with the tubes internal plate resistance. The stage couplers knee frquency is based in part on the net plate resistance. There for higher plates = more bass. Also, the higher plates can lead to more high end loss due to the Miller Effect. Higher plates = more gain. Gain is part of the Miller computations....
Then, factor in the higher cathode resistors that go with higher plates. Higher cathode resistors = lower knee frequency on the shelving filter due to the cathode bypass cap. Bigger resistor = more bass.
Bottom line, without changing circuit values, bigger plates is a little darker, stiffer, bassier, and doesn't overdrive as soon)

The preferred Plate voltage for this stage are around 200V. Lower voltages(190V) have been reported to sound smoother while higher voltages (210+) have been reported as "harsher". (thanks MDRoberts1243)

To anyone: Feel free to start "Tweaking answers Part 2 the skyliner tone stack" If we do about 40 of these there will be no more tweaking questions to ask.

[rutledj]

This is a great idea. I hope others will chime in. Wish I knew enough to provide input.

Rut

[tomrasdf]

The tube plate/cathode values can be 100k/1k5, 120k/1k8, 150k/2k2, 180k/2k7 or 220k/3k3.

Two things that have been puzzling me for some time (great idea for a thread, by the way):

I understand the technical side of why higher values = cleaner, but what is the effect on frequency response, and WHY? Any good web resources out there that do a good job of covering this topic?

Also, as I'm just starting to really understand signal loading, (relative newby here) am I right in thinking that a higher value will load the tone stack differently? Does this make a prectical difference? As in, I can SEE what it does when I mess with the input impedence (ceteribus peribus) on the tone stack calc, but if the plate resistors are switched, should the tone stack also be adjusted for "best" results?

Thanks for starting this thread, heisthl. I wish I had the experience and authoruty to contribute more than questions.

[candh]

This is great for all us non-noob yet not master builders. And in order to avoid futility there MUST be a lesson called "Forum Search for Lazy Dummies"....lol.

Step 1 Click search

Step 2 Read

Step 3 Read some more,,,and if ya can't find what you're looking
for,,,look elsewhere.

Step 4 Return to the forum. State that you've looked high and low to no
avail and ask your question and revel in the fact you haven't
wasted anyone's time including your own.

Class Dismissed

[nickt]

This is a great idea. I hope others will chime in. Wish I knew enough to provide input.

Rut

+1 Thanks heisthl !!

[tonelab2]

The input - A 1meg(preferrably a 1 watt metal film) from the tip to ground at the input jack with the shorting contact (NC) at ground. The tip has a shielded lead to a 22K resistor connected to the grid of the first stage. The shield can be grounded at the jack or near the tube but not both. The 22K vaule can be raised to 47k or 68K and the 1M to ground can be reduced to 470K but the "real values" are 22K and 1M. The tube plate/cathode values can be 100k/1k5, 120k/1k8, 150k/2k2, 180k/2k7 or 220k/3k3. The bypass cap is generally 5uf with values up to 25uf on the 100k plate option. The older "real" values were 100k/1k5 and the newer "real" values are 220k/3k3. Rule of thumb, larger plate/cathodes = cleaner.
To anyone: Feel free to start "Tweaking answers Part 2 the skyliner tone stack" If we do about 40 of these there will be no more tweaking questions to ask.

Thanks heisthl your posts always have +class.
I have trouble understanding the 'clean' thing but enlightenment will come one day. Having built both with the different plate/cathode values (hybrid only) I view it not so much as the clean issue but a matter of chime. With my tin ears the lower values represent Fender clean (sweet) and higher values Vox clean ( chime). Everyone hears differently so YMMV.

[Luthierwnc]

Are you going to put some scope patterns up at various stages? My clones have all sounded very good but I'd love to see your waveforms, signal voltages, knees etc. That might help some of the newer guys on different component values or era builds.

Thanks, Skip

[dogears]

Higher plates add a lot of low end to the tone. The plate is in parallel with the tubes internal plate resistance. The stage couplers knee frquency is based in part on the net plate resistance. There for higher plates = more bass. Also, the higher plates can lead to more high end loss due to the Miller Effect. Higher plates = more gain. Gain is part of the Miller computations....

Then, factor in the higher cathode resistors that go with higher plates. Higher cathode resistors = lower knee frequency on the shelving filter due to the cathode bypass cap. Bigger resistor = more bass.

Bottom line, without changing circuit values, bigger plates is a little darker, stiffer, bassier, and doesn't overdrive as soon.

THis is why, IMO, you can't run a .05uf coupler on CL2 with the high plates. (unless you run a 1uf bypass-but I much prefer smaller coupler and bigger bypass)

The tube plate/cathode values can be 100k/1k5, 120k/1k8, 150k/2k2, 180k/2k7 or 220k/3k3.

Two things that have been puzzling me for some time (great idea for a thread, by the way):

I understand the technical side of why higher values = cleaner, but what is the effect on frequency response, and WHY? Any good web resources out there that do a good job of covering this topic?

Also, as I'm just starting to really understand signal loading, (relative newby here) am I right in thinking that a higher value will load the tone stack differently? Does this make a prectical difference? As in, I can SEE what it does when I mess with the input impedence (ceteribus peribus) on the tone stack calc, but if the plate resistors are switched, should the tone stack also be adjusted for "best" results?

Thanks for starting this thread, heisthl. I wish I had the experience and authoruty to contribute more than questions.

[stelligan]

Might I say that this kind of thread is the reason I continue to frequent here. Hallelujah and Amen!!

[tomrasdf]

Higher plates add a lot of low end to the tone. The plate is in parallel with the tubes internal plate resistance. The stage couplers knee frquency is based in part on the net plate resistance. There for higher plates = more bass. Also, the higher plates can lead to more high end loss due to the Miller Effect. Higher plates = more gain. Gain is part of the Miller computations....

Very cool. I drew it out and amp looking at it on paper right now. Makes sense! Definitely a light bulb moment. Thanks!

[RJ Guitars]

Heisthl - Great Thread. This is the very kind of info that I think makes the forum so useful...

I've found on my "Search" efforts that sometimes I will get hundreds of hits and they can be tough to sort through. An idea like this will condense down that search effort and probably eliminate a lot of unneeded threads.

Thanks - it's great to have you guys available to us. I appreciate the opportunity to learn from you. I am very grateful!

rj

[mdroberts1243]

This is a really great thread and a start of a great series (I hope)!

One dimension of the input-stage tweaking is left unaddresssed... the importance of 200VDC on the plate(s).

What is the sweet-spot range? Does it change with the various plate/cathode resistor options?

[skyboltone]

Are you going to put some scope patterns up at various stages? My clones have all sounded very good but I'd love to see your waveforms, signal voltages, knees etc. That might help some of the newer guys on different component values or era builds.

Thanks, Skip

Hey Skip! Where in the world have you been?

[heisthl]

I'll try and add anything relevant as it comes in as an edit to the first post.

[Luthierwnc]

Hi Skyboltone,

Most of the year I work on guitars. This year I seem to working on work. At any rate, I have a donor Hammond 100E. Pretty cool amp for an EBay special. PT has dual secondaries at either 350-0-350, 275-0-275 or both (loop?). Big OT designed for 7591's at max voltage. Large enough but only 2" deep so real estate conservation is going to be challenging.

Right now I am leaning towards an 80's style. The HRM from last year has those tones covered over British 12's. Designs change nightly.

My post on scopes and frequencies seemed like a good way to get beyond assembly. To a point, you know that if you have the right DC on the spec'ed cap, you ought to get the right noise. I'm interested in what the AC voltages are doing and how the frequencies are modulated through the process. If my scope took pictures they would be an interesting road map along the path.

I'll be hanging around. See ya here, Skip