Tube Audio Must Read

 "A Must Read about Tube Audio"

Please read this document in its entirety, you may be tested if you need warranty service :-)  

There are usually no user serviceable parts inside a tube amplifier. Going inside the unit will void your warranty and is also quite dangerous due to retained high voltages. Always have a qualified tech to perform internal service.

Your tube amp purchased from Grant Fidelity is designed for many years of trouble free use, however like any high-performance product, attention to the fuel that delivers the excitement needs a bit of checking and maintenance. The fuel that drives your tube amp is the tubes. Tubes are fun, simple to install and maintain and it could be quite addicting.

All Grant Fidelity tube components are factory tested for 48 hours under load prior to shipping with the supplied tubes. However shipping and handling can cause you to receive a defective tube or product. Grant Fidelity carry an ample supply of emergency replacement tubes and components in the event you receive a defective product. Please contact Grant Fidelity to arrange for an immediate replacement if your tube amp has suffered from shipping damages. 

We strongly suggest you have a high grade power surge/spike protector ‘designed for audio’ for your components. Warranty services are not provided for surge related problems that can seriously damage your tube amp. In the event that you return a product damaged by a power surge/spike you will be charged for service and both way shipping. 

Please read and follow these simple steps to get the most out of your Grant Fidelity tube amp:

Safety First.

Tubes run hot and need to cool down before removing or replacing. Never touch the tubes when on and wait at least 5 minutes to touch it with cotton gloves to protect your hands after powering down.

Only use the supplied power cable or a Grant Fidelity upgrade power cable with your Grant Fidelity product. Never connect a Grant Fidelity product to an ungrounded power supply or use a device or method that removes the ground pin. Failure to connect to a properly grounded power supply will void your warranty and the user is at their own risk for any such connection.

If you have young children or pets, please select a Grant Fidelity product that is provided with a tube cover and use such cover. 

Location Safety

Always place your Grant Fidelity product in a well ventilated area to dissipate heat, with at least 6 inches clearance above and 4 inches on the sides. Always place on a sturdy stand designed to handle at least twice the weight of the product and is located where children or pets cannot cause the product to fall. Never place your Grant Fidelity product on a carpeted floor. Never place other equipment above or below your Grant Fidelity amp. If your amp is manual bias, please allow for extra top clearance to allow for biasing routines described later.

Grant Fidelity tube amps as with all electronic equipment should not be used near water or damp locations. They are designed for home indoor use, not outdoor use. 


Unpacking Your Grant Fidelity Tube Amp

Please keep all of your packaging material for future transport. If you are moving your amp, please re-use the packing materials. 

If your amp is ‘Manual Bias’ you will need a standard and inexpensive Volt or Multimeter. See Setup – Manual Bias below. 

For warranty service, your product must be returned in its original packaging with all accessories to Grant Fidelity or designated repair centers with proof of purchase from Grant Fidelity . Keep your product packaging for at least your warranty period and your product’s resale value will likely be higher with the original packaging. Grant Fidelity with not cover damage incurred by warranty return shipping to us or our designated repair centers.

Most Grant Fidelity products weigh a lot and require a bit of planning before lifting and placing. Be careful to follow good lifting guidelines to protect your back. Make sure you have cleared your final location and have a clear path to this location and have followed the ‘location safety’ above.


Setup – Install Tubes

Do not connect Grant Fidelity amp to power yet at this point. Try to have a soft work area in case you drop the tube (it happens). Even from a few inches, if the tube lands on a hard surface, it will break or internal structure will be damaged. Use cloth gloves to hold tubes, wipe off any fingerprints on glass portion of tube with a soft cloth. Fingerprints can lead to premature tube failure. Try to use the base of the tube as much as possible for installing and especially removing tubes. Try not put excess force on the glass of the tube because this can cause the seal between the glass and base to break. 

Some Grant Fidelity amps come with resistors connected between speaker terminals. These are provided as a precaution against powering up the amp without a speaker load connected, which can damage the amp. Remove these as you hook up your speakers.

The tubes are matched in the factory and usually identified as to which tube goes where. If not identified, the tubes are in matched quad and can be installed to any of the same type tube sockets. Note the tube guide on the bottom of the tube (male); it is a small slot that matches to the slot in the tube socket (female). Line this up to the tube socket and apply gentle but firm pressure to install tube. You may have to wiggle the tube a bit to get it to line up properly. You will feel a slight snap as the tube properly seats in the socket. Align tube so that it is straight up and perpendicular to the socket. There is a bit of play on the seating of the tube.

On the 300B tube, there is no slot indicator, the 300B tube has 2 larger and 2 smaller pins, examine these and align with the socket carefully. Do not install in the wrong direction - it will smoke! 

Install smaller (pre-amp and driver) tubes first, then larger (power) tubes.

If your Grant Fidelity amp is automatic bias, then you are ready to connect your components (first) then connect to your power. Skip to ‘powering up - burn in’.


Setup – Manual Bias amps

If at any time during this process you see a flash from the power (large) tubes, hear constant popping or static sounds, see a cherry red glow on the tube plate, identify the defective tube and shut down your amp immediately then contact us for tube replacement. A tube could be damaged in shipping and handling but you cannot see the damages with naked eyes. 

It is normal for some popping sounds on start-up and shutdown from the tubes. Some tubes will also produce sound when metal plate being heated up at very high temperature. 

You will need a standard and inexpensive Volt or Millimeter to perform the manual biasing of your system. Manual Bias is often preferred often over automatic bias as it gives you the ability to tune your tubes. Automatic bias is often preferred for larger more expensive tube types (300B, 805, 813’s etc) where you blow the tube if the bias is too far off.

Grant Fidelity manual bias amps are factory biased but still need re-biasing from shipping up on power up. Only the power tubes require biasing, pre-amp and driver tubes are always auto bias on most amps, pre-amps and players.

If you are not familiar with the operation of a voltmeter, read the instruction manual for your meter. Set your voltmeter to the range just above what your manual states or the value indicated on the amp itself. 

Turn the power on and wait 2 minutes to warm up. At this time, there should be no signal going through the amp (ie. CD player stops playing) and volume on the amp set to minimum. 

Insert the mater’s negative (black) lead into the negative (-) symbol at the tube’s bias point and then the positive lead (+). You may have to fiddle a bit to get a constant reading, once you do, hold the leads in place with one hand. Use an insulated screwdriver with correct type of heads to adjust the bias to the required setting. Use very small increments and monitor the multimeter readings to the suggested value. Repeat for the rest of the power tubes, matching all power tube bias readings.

Your first time doing this may take some time, but with practice you can bias the amp in about 2 minutes. There is no danger to it as you are not contacting any high voltage circuit from the bias points. But it's recommended not to touch the metal part of the bias screwdriver when you perform bias in a live circuit. 

After one hour/one day/one week/one month repeat ‘biasing’. Then check monthly for ongoing maintenance. 


Setup – Speakers Connections

If your speakers are rated 8 ohm or greater, connect to the 8 ohm connectors on the back of the amp. If your speakers are rated 4 ohm, connect to the 4 ohm connectors. If your speakers are rated at 6 ohm, connect to 4 ohm first for amp break-in (100 hours), after break-in you can try 8 ohms to see which better suits your speakers, room and ears. 

Never power up your tube amp without speakers connected correctly. 


Powering up, Burn-in


If at any time during this process you hear popping or static sounds, see a cherry red glow on tube plates, identify the defective tube and contact Grant Fidelity for troubleshooting or replacement. 

Please do not leave your amp unattended for long length of time during the 24 hour initial burn-in.

If your Grant Fidelity amp has switches to change its mode of operation, always power down and wait at least 5 minutes before switching to a different operating mode. This will allow for power to dissipate from circuit components. Damaged caused by improper mode switching in not warrantable.

All audio electronic components require some burn-in time to perform to specification. Smaller capacitors wake up generally after 75 hours of use; larger capacitors can take months from new. Tubes generally take about 100 hours to sing and get the full benefit of the beauty of the tube sound. When you first turn on your amp you will still get great sound, but to trained ears that sound will be ‘choked’ and ‘tight’. There may or may not be any soundstage. As your amp gets more time on it, it will start to ‘open up’.

Ideally during burn-in you Grant Fidelity product will be switched on for at least 3 hour sessions.

Roughly, for the first 10 hours keep the volumes at lower levels, less than or equal to one quarter, then for one hour run it at close to half volume (keep treats handy for neighbors), or less if it is too loud for your room. Then run your amp back at less than or equal to a quarter for another 10 hours, crank it again for an hour. Adjust the volumes slightly during this initial burn-in.

Then run it as you would normally and enjoy.

During new tube burn in we suggest that you stay with your system to make sure you can shut down your amp if a tube starts to fail. 

Normal Operation

We suggest you have some decent interconnects, speaker and power cables to get the most out of your music system. Grant Fidelity offers a complete range of performance cabling which offers the industry's one of the best value for the dollar. 

Your Grant Fidelity tube component is ready to make music once turned on; however the sound will open up after about 5 minutes of warm-up. If you are doing some ‘audiophile’ listening we suggest at least half an hour of warm-up.

If you are not listening to music for more than an hour then shut your Grant Fidelity product off. Some other ‘audiophile’ products require that they be left on at all times and can take days to warm-up for optimal performance.  Grant Fidelityproducts do not need such extended warm-up time. 

Always wait at least 5 minutes prior to turning your amp back on after turning it off.


Maintenance / Tube Life

A main power fuse is provided at the amp's power supply plug, accessible by pry open the fuse holder from the outside with a flat knife. Of course unplug the power first. The fuse will blow from large power surges or problems inside the amp. A faulty tube will usually pop the fuse too. Replace only with the same rated fuse. It is a good idea to have some spares handy. 

If your Grant Fidelity amp has Manual Bias, you should check the Bias settings on a monthly basis.

If you move your amp, you should check that the tubes are properly seated and check biasing before turning it on again. 

Once a year you should use a high quality contact cleaner on the rear connectors and headphone jack if your product is supplied with a headphone jack. Follow the directions for the contact cleaner.

Tubes normally run with an orange glow. If you see red or purple, shut down your ampimmediately and check tubes and biases. This is a definite sign of overcurrrent on the tubes and sometimes it will kill a tube instantly. 

Approximate tube life is 3,000-5,000 hour for larger power tubes such as 300B under normal use. Pre-amp type (smaller) tubes life is approximately 5000-8000 hours under normal use, but can last even up to 100,000 hours. It really depends on what we fondly call the ‘tube Gods’, they occasionally need a sacrifice or feeding of a tube or two. If a tube is going to fail prematurely, it usually does within 30 days, well within the Grant Fidelity tube warranty period of 90 days.

Tubes will either fail drastically, usually when new with a sudden flash and will usually pop the fuse too upon this sudden death failure. After 90 days your tube should last its life expectancy. Your tubes are nearing the end of their life expectancy when you hear a loss of detail or power or when your system loses its clarity. We suggest you purchase replacement tubes (see tube rolling below) while your tubes are still fresh and these can be kept as a backup set.

Whenever swapping out new tubes, we suggest doing in pairs or quads and further suggest replacing driver tubes when replacing power tubes. Always request ‘matched’ pairs or quads to ensure balanced tonal operation.


Tube Rolling

Of course part of the fun of owning a tube component is that you can drastically alter its sound to suit your ears, system and/or music by changing to a same model but different make tubes. This is probably the biggest advantage over solid state components which are quite limited in their ability to be ‘modded’ to improve or alter the sound.

If you are new to tubes there are lots of internet forums and info on the web about ‘tube rolling’. To start with tube rolling, only swap out tubes of the same type, any other ‘rolls’ will void your warranty and is only recommended for experienced ‘tubies’ or techs . We suggest you start with pre-amp tubes which are quite affordable and usually offer the most dramatic changes. Tube rolling is at customers' own risk and if it causes damage to your amp, it is not covered by warranty as we do not know what tubes you roll in. If you own a Grant Fidelity tube product and we supply upgrade tubes to you, warranty will remain valid on both amp and tubes. 

If you do decide to roll your power tubes, bias them to the amp’s range.

Changing any tube we suggest that you stay with your system for the first few hours to make sure you can shut down your amp if the new or rolled tube starts to fail.

As with all high-end audio tweaks you should try back and forth testing when comparting tube sound. It is human nature to perceive a difference (especially if you paid for the tweak) as better.

Enjoy your new Grant Fidelity product and more importantly enjoy your music!

Sometimes we get wrapped up in the gear (the playing with the box syndrome?) and tweaking to the point where we forget what it is all about, enjoying the tunes. 

Please register your Grant Fidelity purchase online and don’t forget to write a short (or any length you want) review of your product and dealings with Grant Fidelity on related product page. 

We look forward to continue servicing your future listening needs with great products. 

Your Grant Fidelity Team