Approach to Harmonics

[RossH]

Mark,

I can't find anything said in this post that suggests that you should focus on color of wire over layout.

It is just fine to be skeptical. Healthy. I broke out laughing when he mentioned the color dye and told him that I thought it sounded too far out and most people would think it is bullshit. He said "yeah, most people do". Then he preceded to tell me of an experiment to try. He said "go plug in your guitar cable to your amp and play for a 5 minutes...then turn the guitar cable around and play with it the other direction for 5 minutes. Report your findings." This sounded questionable to me as well, and I have not tried this as of yet.

I'm sure we all need help in the 90% and I'm sure KF would agree that we need to focus everywhere and that layout is important. This whole thing of prioritizing importance and choosing what to focus on is a valid effort. What you choose to reject is up to you.

Please remove from your mind any concept that I am trying to convince you of the validity of these concepts. I am trying to share a few tidbits that came from a conversation with Ken that I thought were unconventional.

The proof appears to be in the proverbial pudding. Ken's amps sound great, while people are trying to achieve his tone without really considering what he is saying on the subtle plane of things. Are they true? I don't know. I may never find out. Does your amp sound like Ken's? I don't know that either.

Best Regards,
Ross

[tubedogsmith]

The point KenF is really trying to make is that you should try things for yourself and see what "YOU" think. It's great to have forums like this but if you're looking to have this info handed to you on a platter then you will never get anywhere. I've tried all the stuff mentioned in this post and even more things that KenF hasn't shared and some of it worked well for me and some if it did nothing I could discern. If you don't think wire type, wire color, wire length, etc... make any difference without even trying it for yourself why are you even here.

[Mark]

Dear Ross and Tube dog

I think the point I didn't make is this, I don't mind working out what I think works and doesn't work in putting together an amplifier, but I do mind when someone is blowing smoke up my rear end, an example of this is of course the Express co-ax story.

This is definitely an attempt to mislead people building clones, perhaps I should still be more open minded, but I have been burn't once.

I would be interested in knowing how you get on with the cable experiment.

I have a cable that I use with my Strat, its a George L cable and I have a piece on string around one of the jacks to assist my in removing it from the Strat's jack. (Thus it is only used in one direction.)

I have tried comparing it to another similar cable and tested it in a manner similar to playing it five minutes one way and five minutes the other way.

The conclusion that I came to was that I didn't hear any difference at all, I think I'd probably hear more difference in my playing then the sound of the cable.

If I were to try the test again, I would want to firstly record a guitar signal for five minutes and then let the recording play through the cable for five minutes etc. I would also want to record the results and have someone play back the recordings to me in a blind folded A/B test.

I would like to point out that I don't dismiss the theory of the guitar cable, but to be honest I'm sceptical.

Ross, I do appreciate any info that you offer us at this group, and I apologise if I have offended you in my role as the devils advocate

I think you also agree that it is important that information is put to the test.

[tubedogsmith]

Mark, I'm curious, the amp you saw with the shielded cable and all the plate bypass components, are you sure Ken built it himself??

[Dai H.]

I think Mark makes some very good points (like w/the shielded cable). It's always good to be critical (and not too extremely critical as to be overly cynical about the non-conventional), keeping things in mind such that sound and approaches to sound are subjective, deliberate misinformation can exist, people might have certain motivations when they say something sounds good or bad, not everything you read on the internet is true(lol), etc., etc. Seems to me that the sort of stuff Ken is talking about would be easier to hear when you have a lot of high frequency response, which may or may not be for you or the amp. Or maybe what we're talking about is more a matter of aesthetic, say that the sort of sound as used by Les Paul (super clean, extended and GLIMMERING highs) and perhaps preferred by Bill Lawrence being the ideal sound as opposed to traditional Fender, Marshall, etc. w/their limited high freq. range, spks, less highs which again, may or may not be what someone prefers depending on how they like hearing things, what they want from their amp, etc. I would also agree if one were to say that the more subtle, or ultra subtle, or insignificant esoteric sort of tweaking should not be the first priority but more of the later or last, and perhaps a beginner should be careful as to not get lost or fixated in "micro-" or "pico-tweaking" (if you will) or experience irrational sorts of design paralysis ("absolutely no use of shielded cable ever", etc.). Even if the Trainwreck aesthetic is not for you it still seems like there would be things to learn in the approach, overlooked subtleties, build techniques, etc.

[ampdoc1]

I'd like to propose a heretical view here. I agree that layout is one of the most important aspects of building and so, when I decided to build a couple of Express clones I went with a printed circuit board. I know, I know,...PCB are crap,... they don't sound good,... the voltages are too high,... yada, yada, yada. I guess I should just throw the amps out, except they sound INCREDIBLE. Lots of harmonics and dynamic range!! (as Ken F pointed out, they produce sounds that can be terrible if you don't play well, which caused me to improve,...and well, that's another story).
But, I don't wish to claim the glory. I used a schematic of Kelly '90 that had passed thru my hands years ago, and laid out the parts close to the drawings I made of that amp. However, I firmly believe that a good quality PC board can make life a lot easier. I didn't have to do anything to either of these amps once I got them going! Both are very stable and I had no problems with oscillations.
If anyone is interested, I used ExpressPCB software and manufacture (no I don't have anything to do with the company, but will vouch for the high quality of their boards) and will gladly forward the PCB file and schematic of the amp.

[snide]

Hi ampdoc1,

Mighty interesting post and you make some very solid points. It seems that lots of folks like the mystical side of tube amps and I also enjoy some of the hoopla but in the end I like a more scientific explaination. I would sure like a copy of the files you mentioned also.

Thanks in advance,

Eric

snide@sw.rr.com

[Mark]

Dear Ampdoc1

I too would love to see your circuit and PCB layout. For the record, I have nothing against using a PCB except for these two factors.

Firstly, I have seen a few amps that have used PCB and when the amp had a fault, a lot of damage was caused to the PCB. In the case of a Fender amp supply rail tracks were destroyed and had to be replaced with wire and epoxied in place. In the case of a Marshall DSL-100, there was a hole burnt in the board which was an inch in diameter. I epoxied the PCB and used wire to route the tracks in there original positions.

Secondly, carrying out mods on a PCB amp is drag, mind you the Marshall mentioned above was quite well made for repair work.

Thanks for your help.

BTW, one of the reasons that I haven't come up with a layout yet is that the caps of preference in a Trainwreck are Mallorys. I'm also again using two 160uF caps in series if I can as they use up too much real estate.

I shall be coming up with a layout sometime this year, at my usual past no doubt!

[Dai H.]

FWIW, not everyone thinks PCBs are crap. I would guess that if the PCB in something is crap (cheap material, thin traces, poorly laid out, etc.), it probably has to do with cost. There's a good article on PCB construction by THD's Andy Marshall found on the Bogner Amps site, for anyone interested:

http://www.bogneramplification.com/Pcboard.htm

[ampdoc1]

Thanks for the interesting link. I won't pretend that I know as much about solder techniques and "aircraft quality" construction as Andy, but years of experience repairing and building guitar amps, and common sense, led me to the same conclusions: layout is critical, (although again, I believe common sense and an understanding of the siganl flow of the circuit can lead an experienced builder to find a good sounding and stable design); and a top quality PCB with thick pads and traces can make all the difference. The boards I had made are not to the standards that Andy mentions, but they are considerably better than you will find in typical "commercial" amps (Marshall, Fender, Peavey, Crate, Boogie, etc.). Also, I installed 1/8" brass eyelets in all the pads to enable exchanging parts without damaging the board.
Another good discussion of PCBs is here: http://www.geofex.com/Article_Folders/p ... -to-pt.htm

David Hicks

[erigm]

I too would love to see a copy of both the schematic and the PCB. Is is possible to upload it to the "files" section of this forum (Omar)? I also thought Andy Marshalls argument was valid and it was a good article. Just about any method of amp construction can be done well or poorly.

[ampdoc1]

I haven't been a member long and I don't know how to upload a message or if this is copacetic with the webmaster. I'll be glad to deliver the files directly in a zip to anyone who requests it. I can be emailed directly on this as well: ampdoc@juno.com

[Omar]

ampdoc1
Feel free to upload the upload the zip file to the board - just use the Add an Attachment feature. If it is popular then I will post it in the Files section.

Omar

[Doug H]

Just a general comment (and to test if I can post to this board )...

Given that according to KF these amps run on the edge of instability, it doesn't seem like too much of a stretch to imagine that there may be all kinds of things that affect the tone/response that you wouldn't normally expect to. If you have ever chopsticked an amp that is oscillating, you know how much moving a single wire can affect the sound. You can hear the tone change as you move that wire from a "stable" to "unstable" position and back again. Now imagine an amp that is designed purposely to ride on this edge. It is going to be sensitive to many factors that would not normally be a consideration with other more typical amp designs.

That being said, IMO good amp building fundamentals should be treated at a higher priority than some of the more "voodoo-y" esoterica. A solid layout and good component choice, tweaking to the desired EQ and etc should always come first.

Here's where I think some of the confusion comes in. For one, I don't believe these amps are "clone-able". They were all different to begin with- tuned to particular cabs, guitars, and artistic preferences. Building an amp like this is more a case of following a general topology and then tuning/tweaking to your individual taste. When the basics are covered and the basic tuning is complete, then you experiment with some of the more esoteric ideas and see where it takes you.

In addition I think there is a problem with having a "cloning mentality" with this amp. Not only are they not clonable, but people have a tendency to take one or two of the wilder things they hear about (e.g. wire color, unshielded wire, aluminum chassis) and treat it like it's a silver bullet. There is no silver bullet of tone with this amp. As KF has mentioned, it's a combination of a multitude of factors.

Just my 2 cents,

Doug

[loverocker]

Interesting reading. I think Doug H is right. If this was a production-line amp, it'd be sensible to talk about making a clone. But if it had been a production line amp, I'll bet the basic design would have had to be 'detuned' to cover every eventuality and component/tolerance variations.

There's something very refreshing in this "on the edge of instability" approach, which is what tempted me in.