Why is lead dress important?

BoomTexan

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I've heard this so many times, and I understand keeping high voltage and high current wires away from where the signal is going, but in general, why is lead dress important? I can't really see much more of an improvement in sound by cutting the wires short, and to get rid of noise, all you need is proper placement. I know that all wires have resistance and capacitance inherent in them, but it shouldn't be enough to significantly impact the tonality of the amp. Well, if you're Ken Fischer, I guess it really matters, but otherwise I just don't see the point other than making it look pretty.

And if lead dress is such an important factor, why are PCB amps looked down on? You have perfect (if the designer knows what they're doing) lead dress and placement for pennies on the dollar of what it would cost you to have a competent builder do the same thing.

Not bashing people who take the time to do it, I'm just trying to understand why people do it.
 

King Fan

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You sound way skeptical about sonic benefits, so let me suggest a practical advantage first. When somebody’s amp doesn’t work, and they send a picture of a box of loopy wire, the fix is never as easy to see or confirm as the guy whose wiring basically looks like a photo of the wiring diagram. Repairs and revisions are much easier, too, if you can get a soldering iron in there without burning a hair ball.

Sonically, it may not matter as much as we think — sometimes. ’70s SF Fenders are not as tight or pretty as the mid-60s BFs. OTOH, they also got more noise suppressing caps and other fixes. Causation or correlation?

Merlin sorta admits that non-ideal heater dress was used in many commercial amps. But he points out it’s still poor engineering. That is a thing.

For every loopy SF amp that sounds OK, we can find a humming homebuilt here that was fixed by moving a wire, twisting a bundle, making wires cross at 90*, and so on. Some lead dress items matter more than others; easier to just do it right from the get-go.

Finally, say two guys have offered you a ride to the game. You know one guy's car is full of fast-food wrappers, dog hair, and Doritos. The other guy, clean as a whistle. Who ya gonna call?
 
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corliss1

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And if lead dress is such an important factor, why are PCB amps looked down on? You have perfect (if the designer knows what they're doing) lead dress and placement for pennies on the dollar of what it would cost you to have a competent builder do the same thing.

I'll jump on this one. The problem is that most (not every, key word there) PCB amps are built to a cheaper price point. PCB *can* and *should* be better in every conceivable way, but they skimp on the design, or the board thickness, or the thickness of the copper, and that leads to failures that don't happen in more vintage-style builds.
 

jrblue

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I can't really see much more of an improvement in sound by cutting the wires short, and to get rid of noise, all you need is proper placement.
Well, if you can't, you can't, but there's a vast number of players, makers, and engineers who do. Just buy an old Pro Junior -- they're cheap -- and after employing the necessary safety procedures, dress and route the leads properly. Then listen. It's rare that I totally disagree with a post, but this one, in my experience, is factually incorrect. However, there's always a matter of degree consideration. If someone plays high volume, pedals, etc. the amp noise might we;; be relatively small potatoes, really.
 

Powdog

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Lead dress is all about avoiding unwanted noise. On a well designed amp you should be able to turn the volume all the way up and not hear any humming or buzzing. Transformers, chokes, A/C and D/C voltages all create magnetic fields which interact with signal/current moving thru wire. Look inside a 50s Valco amp and you’ll see a rats nest. They went as far as to add steel shielding panels to reduce interference. Now look inside a tweed Fender. Introduction of the circuit board not only reduced noise but made logical layout and repair easier. The eyelet board was a pretty good idea. PCBs are notorious for lead dress problems, the “fix” being hand wiring in flying leads across the traces.

Don’t get me started on using the chassis as the 6.3v heater return.
 
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slider313

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Sloppy lead dress, or placement, may cause "cross talk" between two sections of a circuit. This leads to unwanted noise and sometimes microphonics from the previous stage.
 

BoomTexan

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You sound way skeptical about sonic benefits, so let me suggest a practical advantage first. When somebody’s amp doesn’t work, and they send a picture of a box of loopy wire, the fix is never as easy to see or confirm as the guy whose wiring basically looks like a photo of the wiring diagram. Repairs and revisions are much easier, too, if you can get a soldering iron in there without burning a hair ball.

Sonically, it may not matter as much as we think — sometimes. ’70s SF Fenders are not as tight or pretty as the mid-60s ones. OTOH, they also got more noise suppressing caps and other fixes. Causation or correlation?

Merlin sorta admits that non-ideal heater dress was used in many commercial amps. But he points out it’s still poor engineering. That is a thing.

For every loopy SF amp that sounds OK, we can find a humming homebuilt here that was fixed by moving a wire, twisting a bundle, making wires cross at 90*, and so on. Some lead dress items matters more than others; easier to do it right from the get-go.

Finally, say two guys've offered you a ride to the game. You know one guy's car is full of fast-food wrappers, dog air, and Doritos. The other guy, clean as a whistle. Who ya gonna call?
I was actually going to say this as well, just forgot. I totally agree, I've worked on enough rats nest amps to appreciate lead dress, but in this post I was trying to focus on sonic advantages rather than repair advantages.
 

BoomTexan

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Heck, why use those expensive shielded guitar cables when cheap zip cord will get the job done with no significant impact on the tonality?
Hey, I would if not for my college's wildly powerful radio station just a quarter mile from my dorm. That thing causes everything to exhibit ridiculous levels of microphony that just don't happen anywhere else.
 

Paul G.

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I like a neat amp because it makes it easy to see what is going on, but... as long as AC is kept away from signal wires, and crosstalk is prevented by separation or shielding, as long as ground loops are prevented, the rest is just pride. Plenty of vintage amps look like a mess yet work perfectly, and are dead quiet. Look inside a typical Silverface Fender rat's nest and tell me why they are among the quietest amplifiers out there.
 

printer2

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Every wire is a transmitting and receiving antenna. The loop area of the circuit (acting as a loop antenna, go figure) also 'catches' stray electrical fields. Introducing noise or inadvertently coupling one stage to another is the problems a cleaner layout should mitigated.
 

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Didn't think it mattered either until I had crazy oscillation issues in just about every amp I built that had a bypass cap or 2 in the preamp.
 

Jared Purdy

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Lead dress is all about avoiding unwanted noise. On a well designed amp you should be able to turn the volume all the way up and not hear any humming or buzzing. Transformers, chokes, A/C and D/C voltages all create magnetic fields which interact with signal/current moving thru wire. Look inside a 50s Valco amp and you’ll see a rats nest. They went as far as to add steel shielding panels to reduce interference. Now look inside a tweed Fender. Introduction of the circuit board not only reduced noise but made logical layout and repair easier. The eyelet board was a pretty good idea. PCBs are notorious for lead dress problems, the “fix” being hand wiring in flying leads across the traces.

Don’t get me started on using the chassis as the 6.3v heater return.
I have found this post to be very interesting. In as much as all of the replies have been read, this one caught my attention as you specifically mention the Fender tweed amps. I have both the Fender Custom 64 Princeton Reverb Hand Wired and the 57 Custom Deluxe (also hand wired). The PR is so damn quiet when the volume is on 5 on the amp and 5 or 6 on the guitar that you wouldn't know the amp was on save for the pilot light.

The 57 on the other hand, as soon as those tubes warm up, you can definitely hear a hum. Now, that may have something to do with the settings, but still. Using the same guitar, either a Strat with single coils or my LP, with guitar volume on 5, plugged into Instrument input 1 (not jumpered), tone control on 8 or 9, and volume on 5 or 6 (roughly 12 o'clock) there is noticeable hum when the amp is idle. I've noticed that when the tone control gets dialled down to 5 (roughly 3 o'clock), there is a definite drop in the hum. I know the amp is working properly as I had it serviced by a top notch tech sometime ago and he reported nothing unusual about it. Is the hum purely related to the tone control being set to 9?
 

corliss1

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Crosstalk is also a VERY real thing. If you check out some vintage Marshalls, you'll note they have a dab of glue or silicone or whatever holding the preamp wires in a very specific spot. Well, to service a Marshall you have to pull the board and move the wires. If you don't get them in the EXACT same spot, it's crazy oscillation time from all the gain :D
 

Killing Floor

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I thought this thread was about what to wear if a gig is at a nuclear power plant.
I thought this was going to be a Bowie thread!
1668448099663.png
 

Powdog

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I have found this post to be very interesting. In as much as all of the replies have been read, this one caught my attention as you specifically mention the Fender tweed amps. I have both the Fender Custom 64 Princeton Reverb Hand Wired and the 57 Custom Deluxe (also hand wired). The PR is so damn quiet when the volume is on 5 on the amp and 5 or 6 on the guitar that you wouldn't know the amp was on save for the pilot light.

The 57 on the other hand, as soon as those tubes warm up, you can definitely hear a hum. Now, that may have something to do with the settings, but still. Using the same guitar, either a Strat with single coils or my LP, with guitar volume on 5, plugged into Instrument input 1 (not jumpered), tone control on 8 or 9, and volume on 5 or 6 (roughly 12 o'clock) there is noticeable hum when the amp is idle. I've noticed that when the tone control gets dialled down to 5 (roughly 3 o'clock), there is a definite drop in the hum. I know the amp is working properly as I had it serviced by a top notch tech sometime ago and he reported nothing unusual about it. Is the hum purely related to the tone control being set to 9?
With the Tone knob set on 9 you’re directing more signal thru the amp, less to ground. IME buzz, oscillation and crosstalk are more related to lead dress, where hum is more often tubes and filters. Since the amp is relatively new, have you tried different tubes? Can you tell the difference between 60 and 120 cycle hum?
 

Jared Purdy

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With the Tone knob set on 9 you’re directing more signal thru the amp, less to ground. IME buzz, oscillation and crosstalk are more related to lead dress, where hum is more often tubes and filters. Since the amp is relatively new, have you tried different tubes? Can you tell the difference between 60 and 120 cycle hum?
Hi, the amp is about two years old, and I have replaced the tubes as the Groove Tubes crapped out after about a year. I haven't noticed a difference in the level of hum with the tubes. Currently, I believe I have a pair of Electro Harmonix in there (matching). As for the difference between 60 and 120 cycle hum, no, I would not be able to tell the difference. The most definite thing is the drop in hum when the tone is dialled down from 9 to 4 or 5. However, I prefer the tone from the amp (plugged into instrument input 1) with the tone turned up! I've been reading up on it, and it seems as though, barring any deficiencies, it's just the nature of the beast.
 

Powdog

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I’ve built many 5E3s and they can be very quiet and it seems the new 57 Deluxe is a recreation of that amp. If tubes make no difference and you’re not comfortable opening up the amp you might consider taking it to a tech.
 




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