Amp Techs - What to reasonably expect?

[jjk2007]

The tech I used here in Austin had an online cue system for customers. I can’t remember exactly how it worked but I pretty much got notified when my amp was inspected, told what needed to be done etc. I approved the notice and after parts came in etc (a few weeks later) the work was done and I picked up. Seemed like a pretty good system to me.

 

[Grinderman]

The tech I used here in Austin had an online cue system for customers. I can’t remember exactly how it worked but I pretty much got notified when my amp was inspected, told what needed to be done etc. I approved the notice and after parts came in etc (a few weeks later) the work was done and I picked up. Seemed like a pretty good system to me.

That could make sense in 2024 if you can weed out or prevent flakes/no-shows from gumming up the work feed.

This guy's prime and world view was/is very much from the pre-internet age. He's hardly more of this age than my 48-year-old SVT. He has a website but when I asked about something specific from that site he said, "That's not true, I just paid someone to make my site and they put that on there... I don't know why." I don't think he even checks business email.

 

[KellyC]

I had an amp guy in New Orleans that may or may not have breathed too many fumes, and he was painful to talk to but had savant skills with tube amp tech. He took 3-6 months to complete repairs.

I have a guy in Phoenix now who is the best I've ever used, and his turn around time depends on how busy he is, but he would never hold onto my amp for more than a couple of weeks.

 

[RandomKaren]

In a 100-mile radius from me there's maybe 3 good amp techs and all the music stores use them as well as individual players. There's always a wait of some weeks.

 

[Indiana Mike]

Had an amp at a shop for repair.
They held it hostage.
Sat for 8 weeks saying others had priority and if I wanted to I could pay a priority fee to move up in the line.
This was a factory authorized warranty repair.

It became quite obvious if I didn’t pay it was gonna sit.
I paid and had it back in a week.

I hope their shop burnt down and insurance was denied.
That is all.

 

[Grinderman]

Had an amp at a shop for repair.
They held it hostage.
Sat for 8 weeks saying others had priority and if I wanted to I could pay a priority fee to move up in the line.
This was a factory authorized warranty repair.

It became quite obvious if I didn’t pay it was gonna sit.
I paid and had it back in a week.

I hope their shop burnt down and insurance was denied.
That is all.

What would they have done to prevent you from reclaiming your property?

The tech I'm dealing with is the opposite. No priority or rush fees as a policy.

 

[Grinderman]

Update: There's been a couple of text message updates from the tech since last Friday.

He reports the Sovtek WE output tubes have been tested and installed and the output is 361 watts.

Around 320 to 330 watts would be quite healthy, but 361 watts strikes me as questionably high. How plausible is that?

 

[agedhorse]

Not likely unless the line voltage was very high and he was testing a higher than the specified distortion level IME.

 

[Grinderman]

Not likely unless the line voltage was very high and he was testing a higher than the specified distortion level IME.

I'm not clear what he means by the tubes installed with regards to setting the bias and balance or where he's at in his workflow/process. Such a high number and they haven't provided specific contextual or qualifying information to go with that figure to explain why it's so high is what draws my attention. He only said Sovtek WE's are known to make big power.

I've seen copy touting Sovtek 6550WE tubes for having, "thicker plates, improved heat dissipation, higher transconductance, and increased linearity are just some of the inherent aspects of the new Sovtek super 6550's. The resulting performance advantages include 5% higher output power, increased reliability, greater headroom..."

5% higher output than what?

Well anyway, I'm on this ride now so about all I can do is hang on to find out.

 

[Wasnex]

Update: There's been a couple of text message updates from the tech since last Friday.

He reports the Sovtek WE output tubes have been tested and installed and the output is 361 watts.

Around 320 to 330 watts would be quite healthy, but 361 watts strikes me as questionably high. How plausible is that?

The original spec calls for 300W at 3%. My impression is it's rare to find an SVT that will make 300W at 5%. But will they make 360W, yes...the distortion will be higher, maybe 10% or more. So if it's 361W at ~10%, totally plausible.

 

[Michedelic]

This could become a broad discussion but to start with, I'm wondering what others think is a reasonable range of time in which to hear back from an amp tech after dropping off an amp.

Being mindful that things happen, including holidays, and people can be very busy.

Not that I’d want you to rat anyone out specifically, but is said person in the east part of the Valley? Asking for a friend.

 

[Grinderman]

Not that I’d want you to rat anyone out specifically, but is said person in the east part of the Valley? Asking for a friend.

Most of the techs I know of are located on the eastern side of the Valley around the airport and the rest are outside of and east of the Valley.

 

[Grinderman]

The original spec calls for 300W at 3%. My impression is it's rare to find an SVT that will make 300W at 5%. But will they make 360W, yes...the distortion will be higher, maybe 10% or more. So if it's 361W at ~10%, totally plausible.

I'm not sure what he's (the tech working on my amp) doing; the intent or point. Stress testing?

Edit: I can watch this in a little while. Thank you.

 

[agedhorse]

At rated line voltage, it’s very unlikely. In general, a specific tube is not going to be responsible for more power by itself, it’s much more dependent on other design parameters like B+ and screen voltage, output transformer matching, etc.

 

[Wasnex]

I'm not sure what he's doing; the intent or point. Stress testing?

The point of the section I cued up is he's measuring the power and comparing it to distortion. This relates specifically to your question about 360W being plausible.

This shows 340.4W at 10.73% distortion.

A few seconds later he turns down to 240.7W at 5.8%

The spec for this amp was originally 300W at 3%. Ampeg now specs SVTs at 300W 5%. The amp in the video does not meet spec, but it will make 340W.

 

[Grinderman]

The point of the section I cued up is he's measuring the power and comparing it to distortion. This relates specifically to your question about 360W being plausible.

View attachment 5319584
This shows 340.4W at 10.73% distortion.

A few seconds later he turns down to 240.7W at 5.8%
View attachment 5319588

The spec for this amp was originally 300W at 3%. Ampeg now specs SVTs at 300W 5%. The amp in the video does not meet spec, but it will make 340W.

Thank you. I recognize that video but I haven't had the opportunity to watch that portion again yet. I will.

 

[agedhorse]

Without knowing the line voltage and THD of the incoming AC line, there’s no way to draw any conclusions.

 

[beans-on-toast]

The original spec calls for 300W at 3%. My impression is it's rare to find an SVT that will make 300W at 5%. But will they make 360W, yes...the distortion will be higher, maybe 10% or more. So if it's 361W at ~10%, totally plausible.

FYI, that’s David Bird in Elpaso Texas. As I recall, he’s mostly retired from amp tech work.

 

[Grinderman]

Update: The tech called me last night. He's tested the amp.

He said the amp with Sovtek 6550 WE's it was sold with is producing a lot of power but it also puts out a bad low-frequency noise or hum.

Why: It turns out that the provided sextet is not matched, contradicting what the retailer Music Go Round told me. The tech said the tubes tested way off from balance. (I'll confirm and note those details when I'm over there later) The tech chose to merely put those tubes in as a temporary means to get the amp running to establish that it does work.

The back story: The output tubes were packed separately from the amp and unmarked. The selling Music Go Round store insisted that the tubes were matched and tried to convince me therefore it would not matter which socket I put the tubes back in myself instead of having a tech deal with it. (and call it done?) I had to haggle with the store manager to agree to refund me the cost to have the Sovtek tubes tested, installed, biased, and balanced.

I'm glad I refused to follow their guidance. Occam's Razor would point to ignorance as far as the store was concerned instead of something more slippery but now I begin to wonder.

Other than that the tech says the amp itself is in great shape. I have a reserve sextet of Svetlana SED "Winged C" 6550C three times tested, matched, and burned in from TC Tubes. I'm taking those over to put in today and hopefully, that'll be that. I'll keep the Sovtek tubes packed up for TBD.

Maybe I'll press the selling store's manager further with this new information to see what might give.

 

[kesslari]

@Grinderman glad to hear that this is resolving.