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Ampeg SVT Handwired?

#21
Max7 said:
The only hardwired / turret board amp I'm aware of in recent years is the Reeves Custom 225. You might be able to find one used.
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Surely there are lots more? I think all of Matamp's models are handwired/turret board? At least the ones I've owned (including recent production). Lots of smaller clone/"boutique" amp builders use turret boards too.

All my favourite amps are actually handwired/turret board. But this has probably most to do with the fact that I love the tone/dynamics of amps that were designed back when handwired/turret board was the standard. I'm sure I would have loved a good PCB version of a DR201 too.
 
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#23
lark_z said:
After working in quality control for decades, I cannot fathom the challenges of producing something reliable in volume that's intentionally made by hand - when faster, cheaper, and proven methods are available.
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There is always that myth about hand made things. It's always supposed to be better while a machine will do better, with better consistency and way faster.
 
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#24
PCB or "handwired" or... what ever. Both can be made good and reliable or bad and unreliable.
My version of SVT uses eyelets and 2 or 3 mm glassfiber boards, Teflon wire, Ceramic tubesockets etc. It worked 17 years flawlessy, then one lyte blows. Now it works again.
IMG_20231004_114728 2.jpg
 
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#25
Iristone said:
Could be easier to mod or repair for a simpler amp, and saves money for small batch making of limited editions. PCB is more affordable, reliable, and consistent for large-scale manufacturing and more complex designs. Your B-15 belongs to the former group; the SVT is the latter.
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I have several modern amps/ very reliable.
My Markbass combo is in its 13th year.
Modding an amp is far beyond my needs.
 
#26
okabass said:
PCB or "handwired" or... what ever. Both can be made good and reliable or bad and unreliable.
My version of SVT uses eyelets and 2 or 3 mm glassfiber boards, Teflon wire, Ceramic tubesockets etc. It worked 17 years flawlessy, then one lyte blows. Now it works again.
View attachment 5289871
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When I look at this, I think what a mess and the potential for a customer to end up with problem after problem with no real fix. Nobody selling an amp commercially would ever feel comfortable selling and standing behind an amp built like that. Also from a safety perspective for that matter.
 
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#27
okabass said:
PCB or "handwired" or... what ever. Both can be made good and reliable or bad and unreliable.
My version of SVT uses eyelets and 2 or 3 mm glassfiber boards, Teflon wire, Ceramic tubesockets etc. It worked 17 years flawlessy, then one lyte blows. Now it works again.
View attachment 5289871
Click to expand...
I can see agedhorses point on that, but overall, for a DIY build, it's alright. Yeah, things could be a bit more tighty, but that shows how with a bit more prep and PCB work, it could be a lot nicer.

One thing that stands out is that top left resistor on the right board. That's getting to hot. Those type of resistors require a heatsink to get it's max wattage.
 
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#28
6thplanet said:
I can see agedhorses point on that, but overall, for a DIY build, it's alright. Yeah, things could be a bit more tighty, but that shows how with a bit more prep and PCB work, it could be a lot nicer.

One thing that stands out is that top left resistor on the right board. That's getting to hot. Those type of resistors require a heatsink to get it's max wattage.
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Good catch, when FR4 material discolors, that means it's way too hot.
 
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#29
agedhorse said:
When I look at this, I think what a mess and the potential for a customer to end up with problem after problem with no real fix. Nobody selling an amp commercially would ever feel comfortable selling and standing behind an amp built like that. Also from a safety perspective for that matter.
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You may think. Never seen an old 7ender or Ampeg SVT guts?
By the way I've fixed some Mesas, pain in the ass to fix. I won't take those any more on my bench.
 
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#31
okabass said:
You may think. Never seen an old 7ender or Ampeg SVT guts?
By the way I've fixed some Mesas, pain in the ass to fix. I won't take those any more on my bench.
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It's understood that many techs are simply not capable of repairing our amps, they don't have the necessary knowledge, education or skills to do so. That's why we have authorized service centers.

I've seen the insides of plenty of amps, it's not my first rodeo. I worked for Fender and my supervising engineer was the guy who designed the SVT. It's not a matter of thinking, it's a matter of knowing.

okabass said:
[QUOTE="6thplanet, post: 28044834, member: 346287"]
Those type of resistors require a heatsink to get it's max wattage.
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It is not ready on the pic.
The resistor does not get to its max wattage. It had a less wattage resistor, when I was testing. That's why PCB is a bit discolored.[/QUOTE]

If the FR4 laminate is burned like that, it means that whatever the power that's being dissipated, it's resulting in a temperature that is beyond the safe limits. There's more to power resistor power ratings than the published numbers, and that resistor is designed to be used with a heat sink to achieve their published ratings.
 
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#32
All Mesas I took to fix, get fixed.They are not repair friendly, that's why I wont take them.
Sorry, that that resistor and PCB worked wrongly 17 years now.

By the way, if I remember me right Finnish electrical safety office does not first accept Ampeg and Mesa for safety reasons. They have to use a mains isolation or safety transformer.
 
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#33
okabass said:
[QUOTE="6thplanet, post: 28044834, member: 346287"]
Those type of resistors require a heatsink to get it's max wattage.
Click to expand...

It is not ready on the pic.
The resistor does not get to its max wattage. It had a less wattage resistor, when I was testing. That's why PCB is a bit discolored.[/QUOTE]

Just to clarify, you tested with a resistor that discolored the board. Then you replaced it with that one, which worked for 17yrs?
 
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#34
okabass said:
By the way, if I remember me right Finnish electrical safety office does not first accept Ampeg and Mesa for safety reasons. They have to use a mains isolation or safety transformer.
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This is categorically incorrect, all Mesa products exported to Europe have been both approved and certified to CB scheme (IEC 60065 and/or IEC 62368) with all national differences listed below. This is right off of the NRTL certification report that's accepted by your own government:

upload_2023-12-20_17-11-43.png


I can't speak for Ampeg, but every product that I have see has carried similar approvals.

Just because you have a difficult time working on an amp doesn't give you the right to make things up. Either get your facts straight or keep them to yourself.

[edit for typo]
 
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#37
6thplanet said:
It is not ready on the pic.
The resistor does not get to its max wattage. It had a less wattage resistor, when I was testing. That's why PCB is a bit discolored.
Click to expand...

Just to clarify, you tested with a resistor that discolored the board. Then you replaced it with that one, which worked for 17yrs?[/QUOTE]


It was 17 years ago, not sure if I remember me right. There was a "cement" type resistor, and a lyte after that goes to short circuit (or near) and blew that resistor. Then I replace the cap and resistor.
Is there something wrong that that resistor worked so many years (and still is)? If there is I'm very sorry. ;)
 
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#38
okabass said:
Maybe you should check facts too.
There's IEC 62368-1. And it is not so old standard.
Link Removed
I talked safety issues of older Mesa amps like 70s or 80s.
I have no difficult times with Mesas, cause I don't take those.
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Sorry for the typo, that was obviously supposed to be both IEC 60065 and 62368, the clip was from a report that was ~20 years old.
 
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#39
Short4since64 said:
From my experience in building guitar amps (retired EE) to put it simply, the SVT preamp section is just too damn complex to build hand wired. Layout and lead dress matter, PC board designers have taken all this into consideration. You're very unlikely to find anyone doing a "boutique" build of this circuit. B15s, yes - built about 20 of these myself - SVT or V4, no. The power section, maybe. Worked with a friend (a ham op with good knowledge of highpower electronics) who wanted to build one as a PA amplifier. Minor changes, used a 6SL7, two 6SN7s, six 6146Bs and a pair of VR tubes to set the proper safe voltage for the driver stage. It worked fine the first time powered up, but was a real PITA to lay out and wire, not to mention downright dangerous with 650V on exposed topcap tubes, though hams are used to dealing with naked kilovolts pumping RF. No manufacturer would ever go this route.
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It would probably be a serious mess and rat's nest :)
 

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