FROTRONICS
FROTRONICS division of JEFF GRUNDA ENTERPRISES, INC. VERMILION, OH
...Your Satisfaction is Our Priority...
Nationwide Vintage Audio Restoration & Repair:
Do you have a vintage amplifier, preamplifier, equalizer, tuner, or other gear that needs to be rebuilt, restored, or repaired? Frotronics is your premier bench for total solid-state restoration and high-fidelity service.
Specialized Brand Expertise:
While we specialize in SAE amplifiers, preamps, equalizers, tuners, and more we possess deep bench expertise across major vintage solid-state brands, including:
-
Crown, GAS, Marantz, McIntosh, and Phase Linear
-
Adcom, Carver, Denon, Dynaco, Hafler, NAD, Soundcraftsmen
-
Luxman, Panasonic, Pioneer, Sansui, Technics, Yamaha
-
and More Vintage Audio Brands
Great American Sound (GAS) Expertise:
We offer dedicated, expert service for iconic GAS components, including:
-
Ampzilla, Son of Ampzilla, and Grandson
-
Thaedra, Thoebe, and Thalia
Phase Linear Expertise:
Our expertise in Phase Linear PL400 & PL700 amplifiers involves a complete gutting and total rebuild utilizing White Oak Audio premium upgrade kits. In our experience, this is the absolute best way to safely preserve and upgrade these legendary pieces of vintage gear.
Better-Than-Factory Performance:
We don't just fix gear; we improve it. Whenever possible, your equipment is upgraded with state-of-the-art modern upgraded components that far outperform aging 1960s-70s-80s old technology components. For historical accuracy, we maintain a deep inventory of new, original stock, NOS (New Old Stock), and premium used parts.
Rigorous Testing:
Every single rebuild, restoration, and repair undergoes an intensive burn-in and bench-testing phase to guarantee flawless operation and perfect sound quality before it ships back to you.
Ready to restore your gear?
We serve audiophiles nationwide via mail-in service. Email us today with your equipment model and symptoms to request a benchmark quote or ask a question.
📻 Vintage Audio For Sale
Looking for your next piece of classic gear? We have select SAE & Phase Linear equipment available for purchase, fully restored and rebuilt upon request. Contact us today to learn about our current core inventory and pricing.
(Please Note: We specialize strictly in classic vintage equipment and do not service newer or op-amp based audio devices.)
... OUR PASSION & EXPERTISE ...
Master Craftsmanship Built on 70+ Years of Combined Experience
Rebuilding Audio History Since 1990
Established in 1990 by Jeff Grunda, Frotronics is a premier vintage audio restoration shop. Based in Vermilion, Ohio, we provide high-fidelity, nationwide mail-in repair services for discriminating audiophiles.
Along with senior technician Jeff Janezic, our mission is to rebuild, restore, and service your vintage solid-state SAE components and other major brands of amplifiers, preamps, EQs, tuners, and stereo equipment. We bring your gear back to original factory specifications—or better—so it runs perfectly for another 40+ years.
Meticulous Detail, Superior Sound
Our passion for audio excellence drives everything we do. We know our customers can feel and hear the difference because every rebuild, restoration, and repair is completed with meticulous detail. We smile with pride every time we return a newly restored component to you. To us, it means a piece of musical history has been preserved for years of future listening enjoyment.
(Note: While vintage high-fidelity audio is our core passion, we also apply our diagnostic expertise to select electronic equipment and specialty devices.)
What to Expect: Turnaround & Parts
Turnaround times vary depending on the depth of the project—from simple component repairs to major ground-up restorations. Timelines depend on the current bench queue and parts availability. While we maintain a large inventory of vintage and modern replacement parts in stock, rare components and certain units may require sourcing time.
THANK YOU for choosing us,
Jeff Grunda & Jeff Janezic
Frotronics Restoration Team
MASTER AUDIO RESTORATION & CUSTOM REPAIR
Expert Rebuilds, Restorations, Repairs, and More
Frotronics believes in true professionalism and elite craftsmanship for every piece of vintage gear on our bench. Whether you need a total rebuild, a custom repair, or a precise solid-state hi-fi repair, our specialized technicians are always ready to advise and assist you. We back our expertise with an absolute customer satisfaction guarantee—if your repair isn't perfect, we will do everything we can to make it right.
TOTAL REBUILDS
Better Than New
CUSTOM REPAIRS
The Fixer Upper
SOLID STATE HI-FI REPAIR
At Your Command
OUR SERVICE OFFERINGS
Trust The Pros
TOTAL REBUILDS and RESTORATIONS
At Frotronics, total rebuilds/restorations of amplifiers, preamps, equalizers, tuners, and other equipment are not just simple recaps and replacements of a few parts, like other places. All units are totally disassembled and cleaned. All semiconductor devices are removed and replaced with new modern devices which are superior and more reliable than there older components with very old technology. New TOP NAME BRAND electrolytic caps, new PANASONIC, WIMA, or VISHAY polypropylene film capacitors when available, new 1% metal film resistors, new diodes, new C0G/NP0 ceramic caps, new power capacitors, new Bourns or Piher trim-pots on boards, matched modern transistors, open slider and rotary pots are cleaned and lubricated. Complete check of solder joints. Other small components are changed as long as we can install a new modern component. Components are matched as close as possible out of large lots. We use only audio grade components. Plus more depending on the unit!!!
Our bench test equipment is designed so we can monitor both channels at the same time. Very few places are set up or have the proper equipment to do this. This way both channels can be run into dummy loads and observed at the same time. We drive the units hard for 30 minutes to allow it to heat up and to make sure there are no signs of distress. The units are aloud to cool down and during this process we observe all readings to make sure they stay steady throughout the temperature range. We make sure all units are within specs and all settings are rechecked. THD is also monitored and recorded thru the process from 20hz -20Khz on most units as needed.
All units are tested, adjusted, and burned in for at least 24-48 hrs. They are then sound tested in order to verify sound quality and proper operation.
Amplifier rebuilds will come with a certificate that your unit meets all specifications of quality and performance set by FROTRONICS during testing before being returned to you.
Please see Special Notes below for additional information.
........WARRANTY of 2 YEARS ON COMPLETE REBUILDS and RESTORATIONS........
NOTE: The warranty does not cover, misuse, abuse, wrongly hooking up the unit, tampering with the unit, plugging or unplugging cables while unit is powered up, and/or power surges, etc...
Custom Repairs
We can repair most devices and most will not carry a warranty. This is due to other components that may be on there way out that are not detectable at time of inspection. We will let you know if a warranty applies.
All units must be cleaned before any repair and testing. A bench charge will apply to all devices, but will be applied to a repair if you decide to have it fixed. We will replace whatever components that were bad or that you want us to replace and we will make sure the unit is operational, but remember this is only a BAND-AID FIX. We cannot guarantee that the repairs will put the unit back within tolerances if only replacing parts that went bad. Usually when certain components go bad others usually follow. The unit could last for months without another problem or they could go up in smoke the next time you use the unit. Remember these units are old and components have dried up, deteriorated, or have gone out of tolerance. This is why we recommend a total rebuild/restoration if you want the devices to last with a warranty. All units will be tested for operation and short burn in before being returned.
It is assumed that the device you send us HAS NOT been changed, altered, disassembled, missing parts, or modified in any way by someone. Additional charges will apply for extra time spent UNDOING such mods, reassembling, or trying to obtain missing parts before any repairs begin.
SOLID STATE HI-FI BENCH REPAIR
1-Troubleshooting service is available on a time and material basis.
2-We only work on vintage solid state electronic equipment.
3-We have knowledge in a lot of fields so email us with your needs and we will let you know if we can help you.
4-Are bench test equipment and repair tools are some of the world's finest.
SPECIAL NOTES
1-Customer is required to send payment with order and to include return shipping charges before any repair begins.
2-All units must be cleaned first before any repairs or testing.
3-Bench test price will be charged to all units and if you decide to have the unit rebuilt or repaired the bench test price will be applied to the rebuild or repair.
4-Sorry we cannot repair cosmetic problems.
5-We cannot repair meters, but we can look at them and try to repair them, but with no guarantee.
6-All work preformed by trained technicians who know how amplifiers, preamps, and other devices should preform and sound.
7-If a pc board has burnt or lifted traces, and/or lifted eyelets it can sometimes be repaired. Also if a board is burnt through, we have ways to repair this too. These problems will incur an additional charge for the repair.
8-Units that have been previously repaired incorrectly or modified by others may not be repairable and if repairable will incur an additional charge to undo the repair or modification.
9-Incandescent bulbs can be changed to LED's, but not all units light up well with LED's. This is an upgrade for a small charge if you want LED bulbs.
10-We do not have access or change Mains Power Transformers, Knobs, Meters, Lenses, Controls, Power Switches, Fuse Holders, Sockets, Etc... The Only time this is done is upon request and if parts are available.
11-We use SILPADS (silicon rubber) Insulators in all rebuilds.
12-We only accept cash, personal checks, or a cashiers check. This is so we can keep our prices as low as possible. We are not set up to accept debit cards, credit cards, electronic money transfers, or money orders. These all incur additional charges which we can not figure into the cost. SORRY!!!
SECURE MAIL-IN STEREO REPAIR SHIPPING GUIDE
Customer is responsible for the shipping cost both ways.
At FROTRONICS, we restore vintage hifi gear for audiophiles across the entire lower US. We know that shipping heavy, delicate, and valuable audio equipment can be stressful. Because a lot of vintage solid state gear is heavy and fragile, improper packing is the #1 cause of transit damage. By following this step-by-step vintage audio shipping guide, you can ensure your equipment arrives safely at our Vermilion, Oh shop.
We have experienced many shipping mishaps and damage to gear to us do to insufficient packaging. Examples are holes poked in the box damaging the unit, dropped boxes which damages faceplates, chassis, and VU meters. This is why you need an extra layer of protection for the unit. So Please Take Note of this how to package properly for shipping to us:
Step 1: Choose the Right Packing Supplies... Never skimp on materials. Heavy transformers and vintage faceplates will slice right through thin cardboard or bubble wrap. Use Heavy Duty Boxes, High Density Rigid 2" Foam Board, & Heavy duty bubble wrap along with Heavy Duty Packaging Tape. Never use peanuts, they will not hold the unit secure during shipping, allowing it to move around and possibly getting damaged.
Step 2: Prepare and Protect the Unit... Protect the Faceplate, Knobs, & Switches. Use a piece of foam thick enough to cover the depth of the knobs & switches cut out as to go over them. Wrap the entire unit in bubble wrap so it can not move around in the box. Make sure to line the box first with 2" rigid foam on all 6 sides to protect the unit. Fill in any gaps with bubble wrap. Make sure to wrap the plug so it will not scratch or harm anything on the unit. You need to protect the faceplate ears from damage if the box is dropped on a corner or crushed. The 2" rigid foam board does this.
Step 3: Heavy Units may need Double Boxing... If double boxing is needed place the unit, bubble wrapped inside the first box, and packed tight. Then line the second box with the 2" rigid foam on all 6 sides so the first box can not move around. Fill all spaces tightly.
Step 4: Make Sure to Include the RMA Sheet in the Box and Deposit Check... Before sealing the unit box, place the RMA Sheet and check in the box. Make sure you fill the RMA Sheet out completely and keep a copy for yourself. This is safest way to send your deposit check!!!
Step 5: Ship & Insure Your Hi-Fi Gear... We highly recommend shippiong via UPS, but you can use Fedex if you prefer. Also purchasing full declared value insurance for your equipment. Once shipped, PLEASE email your tracking number to us at frotronics@roadrunner.com so we can track its arrival to our shop.
If you have the original packaging material and box place the unit in there and add additional protection around it and place it inside another heavy duty box with the remainder of the steps from above.
NOTE: An item just bubble wrapped or air bagged and placed in a box will not protect it...It needs to be WRAPPED and/or DOUBLE BOXED and lined with 2" rigid foam.
If the item is not packaged properly to us there will be an additional charge for proper packaging on return to eliminate any chance of damage to the unit.
"FROTRONICS is not responsible for any damage to the unit in transit and shipping."
PROTECT YOUR INVESTMENT... IT ONLY COST A FEW EXTRA $ TO PACKAGE IT CORRECTLY...
CONTACT US
EMAIL IS THE BEST WAY TO CONTACT US, (frotronics@roadrunner.com), since we do not have the staff to answer phones or to take care of walk-in customers. We also have unusual hours in the shop... ALL INQUIRIES should be made via email at frotronics@roadrunner.com
Would you like additional information about our rebuilds, repairs, and other related services? Reach out, we’d be happy to hear from you. Emails can take up to 72 hrs. to be answered weekdays. We are closed on weekends. So please be patient for our response. There are only two of us and we are usually very tied up in the shop trying to get your units back to you. Phone calls delay our work which in turn delays getting stuff back to you, this is why we have turned to email response. If we need an immediate response or phone call requirement we will call you or send you a phone number to call us.
Thank You, Jeff & Jeff
Vintage Audio Restoration & Repair|SAE Specialist|Frotronics
Specializing in rebuilds for SAE, Crown, GAS, Marantz, McIntosh, Phase Linear, & more.
Expert nationwide mail-in vintage stereo repair and restoration.