Welcome to MyTubeAudio. A truly different kind of repair shop.

MyTubeAudio, LLC., is a West Michigan-based company that offers “While You Wait” service for tube amplifiers of most any make and most any vintage.  I’m licensed, insured and experienced – I have been involved with tube amplifiers for over 25 years.  Considering MTA’s deep inventory of parts, and the experience of hundreds and hundreds of documented amp repairs you shouldn’t be surprised to discover that most tube amps can be repaired in just an hour or two.  Why not cut out the middle-man and the three week wait and head right to the bench?  You can see your amp get worked on, you get your questions answered, and you’ll KNOW what’s been done. You can get to know your amp tech, and let him know what’s important to you. All work is performed “live” by appointment only – you are always next in line at My Tube Audio, LLC.  Do you have an important show coming up but can’t risk dropping your best amp off somewhere not knowing when it will be done?  MTA LLC can help you.

What? You’d rather have something retro and custom?  You’re covered.

My Tube Audio is also an official dealer for Mojo products, who make an impressive  line of vintage-inspired classic tube amp kits.  I can build to order / custom modify anything you find on their website, so if you’re looking to buy a classic amp but would rather have something in like-new condition without the boutique-amp price, check out and let me know what you’d like to do. It’s a good way to get a great amp for less cost than finding/buying/shipping/repairing a vintage unit.

I also offer electric guitar service – just about anything you might need outside of frets and paint. Wiring, mods, pickup changes, setups, intonation and hardware updates. You can even bring in your own purchased “goodies” and let me do the tricky part. What? you bought new tuners but they are a larger diameter?  No problem. MTA LLC has a well-equipped woodshop that can help.

Amateur Radio fans, please take note. I have a great deal of radio restoration experience (domestic AND European) and can help you get that vintage transmitter, receiver or transceiver back up and running. I have a whole bench full of gear to support radio repair, including test equipment for measuring alignment and sensitivity.

Hi-Fi friends, MTA LLC has you covered, too.  Beyond the basic performance checks, I can measure THD and Intermodulation distortion values, and a host of other aspects to make sure your tube HiFi gear is really operating like it should.

As for the site – Well, I don’t get enough free time to be doing a proper job of it, but I  add things when I can.  Up here on the front page I am going to continue to add more repair and project photos, with small comments here and there. It’s not as good as full pages dedicated to each item, but it’s better than nothing.  Enjoy what you see and feel free to contact me via the Email address shown in the photo above.

Thanks for stopping by – Dan, N8ZJV

MyTubeAudio LLC., Holland, Michigan


A flicker of hope for those DT-50 owners who have suffered a blown power transformer (or two)…


If you read the forums, even on Line 6’s own support pages, you will quickly recognize that something went quite wrong with the DT50 amplifier. It has also mysteriously disappeared from their catalog without explanation leaving its little brother, the DT25, behind.  I find it especially odd, since the owners of DT50 amplifiers speak so well of them.  Let me relate my recent experience with a customer’s DT-50 and the long road to putting this amp back into service.  I’m not a big fan of modeling amps in general, but I will happily admit that the latest generations have really improved in terms of real, usable tones that actually approach what they claim to mimic.  I’m also not a big fan of overseas contract manufacturing on so many levels, but especially on quality control. Questionable tooling, non-existent quality systems, using cheap hand labor to replace more reliable automated assembly, rampant intellectual property theft, and ongoing counterfeit parts supply chain issues all leave me feeling the best amps are still made in the west. Things can go wrong, and do.

The DT-50 has, if you have read even a few forums, been plagued with a very high failure rate of power transformers. To Line 6’s credit, many were replaced under warranty, and (in a slight nod to the scope of the issue) they continue to offer replacements to some customers who have, by now, recently fallen out of the warranty period. They even offer, in some cases, to pay postage one-way.  The caveat here, is that, again if you follow the posts, many of these replacement transformers are ALSO failing some months later. The transformers that are failing are made by Chuang Meei in Taiwan, part number 11-30-0044.

Shipping an amp is an expensive, if not risky proposition, so I was not surprised when my customer told me he’d rather have the repair done locally, and preferably without using another Chuang Meei part.  The owner had not had much luck talking to Line 6 initially, and the offer to repair it out-of warranty apparently came a bit later in their conversations. It was also suggested that he might bring the unit to a Line 6 service center, and he was duly given a couple of contacts in Michigan, although not in our area.  When contacted, those shops were backlogged on repairs or “unable to get that transformer right now”, he was told. This customer really liked this amp, and had it integrated with a few other Line 6 products in a seamless way, and he was not about to give up easily.  Replacement parts are not something Line 6 sells much of – only about 18 items are available via their store, mostly knobs and pots and logos, unless you are a “service center”.

Having heard rumors that Mercury Magnetics actually make a DT-50 power transformer replacement, he contacted a MM distributor, JMI Music in Fort Worth, Texas (; 817.284.5877).

While not a catalog item, it turns out that they DO make one, and told him they could wind him one on special order. So, order placed, and a tranny was delivered about two weeks later.  It is a model BOG-DT50-P and cost in the neighborhood of $218.  Not cheap, but MM has an excellent reputation for made-in-USA quality. I was disappointed to find that, when asked, MM specifically did NOT guarantee that the color codes of the unit would match up with the original, even though it was apparently specially-wound for the DT-50. That meant we had to verify every circuit and ground to make sure it would install correctly.


There are 15 wires on this unit. Line 6 again disappointed us by repeatedly insisting, in multiple calls, that a schematic was not available due to “non-disclosure agreements” (not the lack of an NDA, as in, with me, but an NDA itself, leading me to think perhaps I was dealing with a contract service center and not an actual Line 6 tech department), and further, they would not/could not even verbally identify, by phone, just the color codes of the wiring of the original DT-50 transformer. (So those risky wire colors are secret now?)  Again, none of this would be a big deal, but MM effectively had told us the colors may not match up.

Here’s what we did to prove it one way or another.  Using an LCR meter, and knowing the original PT had a least a shorted primary, we shorted the primary of the new MM unit and made AC impedance measurements across all the secondaries and noted them down on the MM transformer’s supplied pinout documentation. We then measured the DT-50’s shorted unit’s secondaries and compared values. We found that it was pretty obvious which windings were which based on relative resistances at a test frequency of 120 Hz. To double-check the work, I followed those connections back to the PCB traces and to each of the diodes and filter caps to verify that the voltage of each secondary was compatible with it’s proposed power supply circuits. No surprises found here, folks.  In this case, everything matched up perfectly.  Well, except one thing.

The mounting feet of the new transformer do NOT line up with the original threaded PEM-nut inserts in the chassis. They are about ¼” off in one dimension.  Just enough that if I drilled 2 new holes, they’d be compromised in strength as they would be really close to the PEM-nut inserts. A better plan would be to swap out the mounting brackets from the original transformer and use them instead on the MM. Fortunately, the core spacing of the main bolts did match, so this actually works out pretty well. All four bolts must be completely removed to do this, and some new spacer washers placed in the top 2 bolts so the end-bells still retain a cooling air gap of about 2mm at the top (see pics) like it has at the bottom.  Pay attention to the MM paper and plastic insulators on the screws and get them all back into place, it’s tricky, but they are there for a reason. These pics show the Chuang Meei Feet now sitting under the MM iron:

Once that was accomplished, it was a simple matter of bolting it in place and splicing the matched-color wires together using the pre-tin, then sweat together, then heatshrink method, to keep the original molex-type connectors rather than soldering the new leads directly to the molex headers.

Note that the center-tap of the B+ for this amp goes to ground. MM placed a flag sticker warning label on the B+ green/yellow wire about this. In some rectifier designs, shorting this to ground will result in a short-circuit through the diodes, but in the DT-50 on the bench here, it was used and grounded.


Before I connected the secondaries back up, I applied 12.5 VAC (via the variac) to the power input of the amp and verified I had 1/10th of the expected AC voltages on the each of the secondaries,  before I risked applying the wrong voltages to the PCB circuitry. Everything looked dead-on, so we connected all and powered up the amp. In this case, the output was a perfect 50 watts at clip into 8 ohms, the bias was very close to spec, and after all functions were verified a solid burn-in was completed. We then re-dressed all of the leads safely as per the original wire dress.  As a result, one VERY happy customer took his beloved amp home knowing that this problem should never return.



Power transformers can fail for a number of reasons. Often, an internal, self-resetting thermal fuse is to blame when it fails to re-set. Other times, arcing across windings is to blame, insulation issues, or a shorted output tube connected without an HV fuse will take out the smaller-gauge B+ winding by drawing too much current. I like to do post-mortems on parts whenever possible. In this case, we tore the original unit open and found that one side of the 120/240 primary was simply shorted out. Hopelessly shorted, with no signs of heat or smoke. Perhaps a winding error, or a tolerance issue. Transformers get quite hot, and copper expands and contracts a lot with temperature cycling. It has to be accounted for in the design. To see an occasional tranny go bad is to be expected.  To have a whole group of them go bad is either faulty design or faulty manufacture, bad tolerance stack-up, poor materials or a combination of these.


I suspect Line 6 is acutely aware of what happened, but they are not talking about it and not being very helpful, either. If this case is typical, and they expect to keep their (once-loyal) customers, they should be providing better customer support for their products, especially at this price point of equipment ($1800 list). Simply sending in the transformer alone for an exchange/replacement would have been a low-cost $35 (OEM price) solution they should have offered (only 4 screws and 3 connectors to remove/replace).  Leaving the customers hanging or offering a $65 shipping bill and waiting weeks to get an unimproved replacement is not a good response to an obvious quality issue. My guess is that they simply did not have enough trannys to go around (some threads recalled being told they were out of stock) or the whole lot were so suspect that they just stopped DT-50 amp production altogether and tried to limit economic damage while they could. Sourcing from Asia is always risky.  Now you know.


I’m basically putting all this out there so other people, who until now cannot get their amps fixed, can know there IS a solution, and this is what it takes. Whether it’s worth it to you, well that depends how much you like the amp. For me, I‘d have to say it is one of the best-sounding modeling amps I’ve ever heard, and worth making it right. By the way, if you are brave, and just have to have one, I noticed Line 6 has “Refurbished” DT50’s quietly available via their online store for the time being, at $1,039.00.

I do wonder, at that price, which power transformer do they have in them?


Dan , MTA, LLC










2016 – The New Year!

Posted: January 20, 2016 in Uncategorized

Thanks for visiting MyTubeAudio. 2016 is off to a great start already!

The Business –

It’s been a busy couple of years – the daughters are growing like weeds, my career changed paths again, and the amps keep coming. About the only part of my life that feels consistent is the repairs. For a few years now I’ve been doing exclusively while-you-wait repairs for tube gear, one, two or sometimes three per week, and I’m get nothing but wonderful feedback from the customers.  As to stats, well, most repairs take around two hours, sometimes more or less, but the average bill seems to hover below $100 when I’m billing $40/hour plus parts.  I had some feedback that the site was looking a bit dated, so I figured I’d better take a rare quiet evening free and update things a bit.

The Bands  –

The Voice and Rocket 8 are both active these days – The Voice had a strong show at a local theater and just about filled it – we made well  more than enough to cover costs plus pay the professionals who took care of lighting, sound and serving the crowd.  During that show we showcased some new material that we’ve been working on the in the last year and released some new material on iTunes as well as our back catalog for download. We followed that up with a nice Christmas show and are starting the new year by doubling-down on the remaining unfinished mixes, which so far are sounding pretty tasty.

Rocket 8 has been keeping a steady clip, so to say, at about one show per month per the PLAN, and in the last year we added a second guitarist, which really filled things out and has allowed me to get more familiar with keyboards, adding more texture and breath to many of the danceable 80’s covers we specialize in. There is a demo on YouTube out there now – I’ve been mixing the live audio multi*tracks for the past  few months  as time has allowed while Glen has been putting together scraps of video to make a medley of material highlighting the band’s offerings. Hopefully it will bring us some new venues to ply our trade in.  There are rumors about a possible Mac Island show this year – we’ve committed to it but have to get the venue on board with it- there is a good chance it will happen for 2016. I think the last time we played there was summer of 2013. We’ve also invested in gear again – adding a digital board (Midas/Behringer X32) and picked up 2 x 18 JBL subs and 2600W of Crown power to drive them. Active monitors were also added, and the upshot of all of the investment was deleting the racks of gear we used to carry – a cleaner, simpler PA with tons of headroom and all of the FX we would ever need. We don’t clip anything anymore and are getting very good feedback on the sound overall. iPad access to system tuning is a wonderful thing – you can walk around a room and do anything you might want to, and save your changes too.

The Site –

I do have more repair pictures to upload -I’ll make an effort to get them out there this year, I promise!!  I get a lot of comments from customers that they have indeed taken a look at the site before calling, so it’s time worth spending.  I’m a bit hesitant to publish my contact details here, but let’s say that I can be reached most easily via CraigsList Grand Rapids where I have kept an active ad for years – Search Tube Amp Repair under For Sale – Musical Instruments for all the contact information.

The Studio –

On of the benefits of the Rocket 8 transition to a digital board is that all the rack gear came back home where it belongs. Not that I use it much but it’s nice to have everything back in place and wired up for service and not out in harm’s way.  As part of the new job I started in November of 2015, I took some severance pay and invested in a capable laptop, and that has resulted in a lot of recording and mixing “completely in the box” as they say. It’s addictive in some ways, but I too, like so many others have noted how it lacks warmth. I’m using Adobe Audition on that machine, as I used it with my former job doing voice-recognition prompts for so many years that it was a natural choice. I do miss my extensive plug-in library that we had on the corporate license, but that can be cured a little more investment. I’m finally happy with a PC that can handle multi-track audio gracefully without complaint. Funny to think I had to lose my job to get to that point.

The Day Job –

It took a couple of months, but after Visteon shuttered the doors in West Michigan, I landed on my feet (with more than a few former colleagues) at a good company, Gentex, just a short drive away. I couldn’t be more pleased, as it’s a well-run place. My current role is as a Senior EMC Test Engineer, so once again I’m playing with some really expensive toys, interesting antennas, and radio. My latest work will have me playing around well into the double-digit GHz domains, looking for truth and harmonic content above the noise. I love this kind of work, and the research that goes with it, I’m back into a learning mode and that feels great. Good to be employed, too!

I wish everyone a safe and happy 2016 – if you are considering having some tube amp work done, please get in touch – we can fix your amp together,quickly and have fun doing it, for less cash than you’ll likely pay elsewhere.  The best part is you take it home with you the SAME night. That’s what while-you-wait service means – NO WAITING, and exactly the things you want done get done, and done right.

-Dan Brasier, N8ZJV

MyTubeAudio, LLC

Holland, Michigan



Here is a random collection of photos from 2014 work.  I’ve been terribly busy, 2 bands, engineering day job, family (2 young girls + wife!) and tube work… lots of it.I don’t have much time to post here but I think I can upload a bunch of new pix and call it good for now!  (oops – I now see that they upload in a random order… if I get time I will try to sort them later. )

By the way, the “While-You-Wait” repair thing is going GREAT!  It’s so much more enjoyable and the customers are loving it. I should have done this years ago. I no longer take drop-off repairs of any kind, but I’m doing morework.  2015 started with a bang – usually 3 appointments per week. Let the solder fly!!

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Epiphone Electra needs a heart transplant

Posted: January 25, 2014 in Uncategorized

This Epiphone had an issue with a bad photocell/lamp combination – a special optocoupler that is no longer available – and so no tremolo.  I managed to retrofit a new lamp into the original assembly and only had to make sure the current driving it was within spec and still performed well in the tremolo circuit.

Epiphone Electra repair (25)

Epiphone Electra repair (28)

Epiphone Electra repair (29)

Epiphone Electra repair (30)

Epiphone Electra repair (32)

Epiphone Electra repair (38)

Epiphone Electra repair (39)

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Epiphone Electra repair (41)

Epiphone Electra repair (43)

Epiphone Electra repair

SRV Strat Teardown

Posted: January 25, 2014 in Uncategorized

Sometimes a guitar just needs to be blown apart, gone thru end-to-end, everything cleaned and lubed and tightened, and anything replaced that’s not up to snuff. Then you do a complete setup from scratch knowing that there are no hidden demons. Such was the case with this SRV strat.. Also of note here is the new second bench area set up for RF and other non-tube work.







Well, I have not posted here in a very very long time. A few changes have happened.  We have daughters, 3 and 5, which take a lot of our time. That’s one reason, another is just the speed of life. So much to do, so much remains undone each day. I have acquired the address, which is kinda cool. The biggest change has to be a shift in our general business model, namely, I now work solely on a “while you wait” basis.

No more drop-off, pick-up of tube gear requiring repair. We make an appointment, we fix it, and it leaves the same night. The feedback has been very good on this. It was a good choice, and is possible because I stock a lot of replacement parts, well-organized. I have been as busy or busier since this workflow shift about a year ago.

I have been collecting some pics of the work – not as consistently as I should, but still, there are a lot of photos to post, and I think I need to get a few more up here today.  As I type this, a blizzard churns outside of our Holland, Michigan home.  The kids are home, school was closed due to weather, and there is a certain Zen to being in a warm place as the wind rages.

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