Ever lose track of time and cost on a project?

[nevetslab]

It all started with a simple investigation into a whether a power transformer I had that was from a KT-88 based amplifier might work as a replacement for a failed Peavey amp's power xfmr. Turned out it was not suitable, but looking at the available chassis and both a working Power and Output transformer, it got me thinking. Putin's war on Ukraine and US Sanctions on Russia in response has screwed up access and cost of vacuum tubes. I have a small collection of power tube 'pulls' from our rental inventory over the past 13 years.



I had already looked at using the recent Yamaha T-100 Rack Mount Guitar Amp that I had modified for use in testing/screening 6L6-family tubes, 5881's and EL34 tubes, but it wasn't quite suitable for KT88/6550 power tubes. Could have made further mod's on it, but it was not a split-supply system, providing High Plate Voltage and a second lower Screen Supply voltage system that I'm used to. Ampeg SVT-CL amps had been my favorite amp for testing power tubes, as their protection system shuts down immediately with any power tube failure, but, of course, not a convenient set up for use any time I'd need it. I glanced over at the broken SVT-CL having a failed power xfmr...but, I had also acquired the replacement. If the owner didn't want it restored due to cost, then perhaps. He wanted it back, so that's gone.

This chassis had the space to build a different amp into it, and I had the main ingredients needed for the power. Add 6.3VAC Heater xfmr. What to build it as....wanting a working proper amplifier circuit in this chassis. How about the Hiwatt DR201....that's freshly in my mind from having serviced one back in December.

So, here it was, May 13, 2022, and decided to see where this goes.

63 days later, 370 hrs invested and $576 in expenses, not counting on-hand materials used, I have gone from that to this:



I had no idea what it cost or just how much time I was spending. I did find an open stretch of time available and just got busy, stopping here and there to take in work as it arrived. It's up and running, and sounds very impressive as a working bass amp. Definitely kicks ass with the bit of playing time I've had with it just using the shop Ampeg BXE115HL4 15" bass cabinet that's been in here the past 13 years.

I haven't yet started sorting / matching power tubes with it, apart from the first pair of Sovetk 6550's I plugged in not even two weeks ago to see if I had a working system. That and the quad set of J/J KT88 power tubes that I plugged in next that belong to AuntieM....a set purchased for one of their Orange AD200's...and found one tube wasn't good, and exchanged it with another from Antique, using their Apex Tube Matching system Wasn't an exact match....runs 4mA higher at 20mA/tube setting nominal, but easy to set up, having the bias pots and 1 ohm sense terminals right there at the rear panel. I haven't yet used it for screening preamp tubes, but having two high gain channels in the front end, this should work fine for that task. I haven't yet set anything up for screening/testing ECC82/12AU7's. This amp uses ECC81/12AT7 as a driver tube, so it will suffice for that as well. It's always powered via Variac and Power Analyzer, so this appears to have turned out quite well.

Looking forward to taking it over to the Guitar Dept and hear it on some of our larger bass cabinets. And looking forward to hearing this together with a Hiwatt DR201, from which this was built as for the test amp. Doesn't have the EXCELLENT Partridge TH8108 Power and 7239 Output Transformers, but it has the same circuits as used in their current production amps, as well as the same layout on the Preamp Turret board, same components and similar layout on the Power Tube Turret board. Wiring is different, power supplies are a little different. Separate HT and Screen windings, just here with two separate power transformers.

Next task is modifying the DR201 schematic I've created in NI Multisim 11 into this revised amp/test fixture system. Still haven't created a front panel or rear panel for it, though for test fixture use, they'd be removed anyhow.

[Tom Phillips]

...63 days later, 370 hrs invested and $576 in expenses, not counting on-hand materials used...

Wow!. That's a bit shocking but should not be totally surprising to those of us who have built custom amps and other projects from scratch. I commend you for sticking to this while running your business AND contributing advice to other MEF members.

Rock on,
Tom

[Enzo]

I'll just build my own amp and save lots of money...

[Randall]

I'm not even going to read any of the posts, I will go straight to my answer. Yes, all the time.

[Chuck H]

Well there's something to this genre that precludes labors of love. And, of course, kudos to those that do this for a living and find themselves on the wrong side of this line commonly, BUT...

I never made a penny from any amp I've built. Any customs I've made have been projects that "I" wanted to build and were funded by customers, sort of, basically. I really just used the "selling an amplifier" guise as a smokescreen to fund something I couldn't afford to do do with my own money. And it's been a fun ride to be sure. Probably not even over The particular mind that makes this avocation of ours possible is ever bound to pursue it's own goals and needs almost regardless of reward. It's peculiar behavior to be sure since it doesn't serve the bottom lines of shelter, security and procreation. But like it or not we're nerds like that. I regret nothing.

[g1]

I'm with Randall. Maybe not all the time, but sometimes I end up telling myself "I'll just have to think of it as a seminar". Some seminars are more expensive than others.

[Enzo]

We have said it before: I charge people for the work I do, I don't charge them for the learning I have to get to do it.

[Mick Bailey]

I spent well over two years on a project - several hundred hours of research, electrical, electronic and mechanical work to re-design and rebuild a really rare 50s tape machine into a standalone preamp that could be used in a modern studio. I charged £400 ($480) and this included half a dozen NOS Mullard tubes, custom metalwork and a whole bunch of other parts. At the point where I felt like sprouting jackass ears the studio gave me a call and said this was their go-to preamp for vocals and they were using it in preference to their Neve preamps in their SSL desk, so there's some satisfaction there, though no money in it (for me) Also, it had 'done the rounds' and been turned down by everyone else, so was a challenge.

[Greg_L]

I started down this path mostly out of necessity and curiosity. I'm a pretty busy musician and I've been burned by local "amp techs" one too many times. And within reason, I generally dislike handing money to someone to do something I could do myself. So I started reading and studying and learning how to work on my own amps myself. This forum, for example, has been very good for my self-education. First was just maintenance. Then came mods. And now I've got several successful complete builds, restorations, repairs, and retrofits under my belt. I've even learned how to do tolex. Yuck.

I'm nowhere near pro or expert. But I'm competent enough that I take in other people's gear from time to time. Most of this stuff is from people I know, or a friend of a friend, or just guys in my local music scene that need work done in a timely manner. Since "amp tech" isn't my job, I can take my time and learn from it and not really have to charge much. I make people pay for parts, but I'm pretty lenient with my time. I usually just let people pay me whatever they feel they can or we work out some kind of trade or something. I know this is not a good business model, but I'm not a business. I'm just a guy helping people out my peers when I can and learning from it. So as far as time and cost goes, I'm probably way deep into the negative.