FAQ

Click here for a technical explanation about Adaptive AutoBias written by Marcel Croese, the engineer who designed it.

All PrimaLuna EVO amplifiers are currently equipped with EL34 power tubes. However, you can substitute these by any 6550, KT66, 6L6GC, 7581, KT88, KT90, KT120, EL37, or even a 6V6GT into any of our amplifiers.

KT150S is NOT recommended for the ProLogue and DiaLogue (Original) 1, 2, 4, 5, 6, 7, the Classic Integrated Amplifiers and the EVO 100 Integrated Amplifier. Other amplifiers like ProLogue Premium, DiaLogue Premium, DiaLogue Premium HP, EVO 200, EVO 300 and EVO 400 have proven to work well with the KT150S tubes.

In the past, the ProLogue Two, Five, Seven, and DiaLogue Two amplifiers came with KT88 tubes, but these can also use EL34 tubes. They are just a bit "higher” biased. The ProLogue One, Four, Six, and DiaLogue One amplifiers came with EL34 tubes but can use 6550 and KT88 tube types without issues. The tubes will run slightly cooler, but many customers have successfully used these higher-dissipation tubes.

We decided on the High and Low bias levels by the choice of several listening panels and of course within the technical limits given.

Each tube will have a different effect on the sound. Adaptive AutoBias will adjust to the new tube type, making experimenting with other power tubes very easy. 

Yes, that is normal for power tubes. That blue glow is just stray electrons bouncing off the glass. Some tubes will have a more noticeable glow, even amongst a matched set of tubes. Sometimes, the glow will burn off. That is also normal. What is not normal is a bright blue or purple glow or flash coming from inside the plate structure of the power tube. If you see a bright blue or purple glow coming from inside the plates, or if you ever notice a bright flash from a power tube, turn your amp off immediately and replace the tube.

It happens rarely, but a tube can lose its vacuum. This problem is usually caused by a high, unintended mechanical force applied to the tube or the tube pins. In any case, the tube should be replaced. If it happens again, check if the tube socket isn’t bending a pin of the tube, causing a crack, which causes the loss of vacuum. In that case, also replace the tube socket. Be careful with using so-called tube pin straighteners. They might cause a crack. Usually, a good-quality tube socket does enough of the job.   

No, this can be a characteristic of the tube. Different brands of so-said same models can still react differently. 

It may be better to ask the question differently. For example, can I replace the standard PrimaLuna tubes supplied with the amp with tubes from another brand or even with another type of tube? 

In principle, all tubes in a PrimaLuna amplifier (or in an amplifier of any other brand) can be replaced by tubes of another brand or even by another type as long as they are equivalent tubes! The contact pins of the tube to be replaced must match the new tube, and the electrical properties must match. There are plenty of reliable tables on the Internet that provide information on this. Sometimes, an (almost) equivalent tube draws more current than the initially used tube. Then you have to find out if the power transformer can handle that. 

Power tubes and the corresponding tube socket are often equipped with a "slot" to ensure the tube is placed correctly in the socket. Pay attention to that! Replacing a tube will go smoothly if you do this cautiously.

This can happen. The BTI is a Bad Tube Indicator. This doesn’t mean it is an all-mighty computer having everything under control. Such computers don't exist as you probably already know.  

Sometimes, when a piece of tubed equipment is noisy, the cause is a bad connection between a tube and the socket, not a noisy tube. Quite a bit of tubes that have been returned to us for warranty replacement, are not noisy at all.

Remember: Tube sockets are not highly reliable connectors! If the sockets are dirty or not tight enough, or if the pins are slightly "thinner" than your original tubes or have a little grime on them, it can cause one or more pins to be unable to make solid contact. This can result in noise.

So, make sure your tube pins are clean before plugging them in. Also, make sure your sockets are clean and tight. Many times, just the act of removing a tube and re-seating it, either in another position or back into its original spot, can alleviate the problem.

A known and effective way to clean the pins of your tubes is to "insert" the tubes a few times in "brass-wool". Usually, this material is used for cleaning the tip of a soldering iron.

Power tubes like EL34's and KT88's are good for about 2500 hours or more but may go longer in an amplifier with a conservative design. Small signal tubes with numbers like 12AX7, 12AU7, and 6922 and rectifier tubes like 5AR4 may go 10,000 hours. So, you get years of enjoyment. Using a tube tester may or may not tell you if you need a replacement. The best approach is to buy a new set of tubes, install them, and listen.

Many vintage tubes were labeled with ink designed to fall off easily. So do not touch it. If you get it wet at all, it may go away right in front of your eyes, and just shipping and pulling it in/out of the box can damage the logo. If the box is an original vintage box, open it carefully under the flap using a butter knife. The ends can tear right off easier than you would believe, and some people prize the boxes.

As for the glass itself, despite what some people might tell you, the oil on your fingers will NOT damage the glass or leech through it. Tubes are not halogen bulbs. Tubes may get hot to the touch, but your finger oil will not cause the tube to break when heated up, nor will it affect tube life or sonics. It will not go through the glass.

We recommend not pulling tubes in and out too many times to compare tubes. The best way to do this, if you have to, is to spend a day with one tube and another day with the next tube. We know it is tempting to pull them in and out a lot because it's fun, but when you do, you may loosen the tube socket if you go in and out a few hundred times. Tubes, sockets, and tube gear are very durable. But use common sense. In addition, tubes need to be left undisturbed to sound their best.

Many European tubes in the 12AU7, 12AT7, and 12AX7 families may flash brightly when you first power up your gear. This flash is normal. It is also normal for the intensity of the flash to vary from tube to tube, and the flash intensity may also vary or even go away as the tubes age. What is not normal is a flash from power tubes. If this happens at any time, turn off your amp immediately!

We get asked this question a lot. With a power amp, you would typically not leave it running 24 hours a day. Power amps produce heat, and they use a lot of electricity. Preamps and source components that use small tubes are another matter.

Tubes age in a couple of ways. One way is they lose emissions over their lifetime. Basically, they run out of gas. Tubes don't just "quit" suddenly. They gradually lose their drive capability with use. Small signal tubes like a 12AX7 or 6922 will work well on average for about 10,000 hours. If you leave your equipment on 24 hours a day the lifespan of the tube will not be long.

It depends on how picky you are. It's like a tube of toothpaste. Things peter out at the end, but it seems you can always squeeze out a little more. Some products (and audiophiles) are pickier than others.

The other way tubes age is they become noisy. Tube noise can present itself in several ways. Sometimes, the noise may sound like popcorn popping softly in the background or become a loud roar. It can happen to any tube, including brand-new ones. The most common reason we have found for tubes becoming noisy is the coating on the filament becomes compromised. You can make the noise worse by turning your gear on and off a lot. 

Usually, it's a good idea to leave your gear on during the day if you plan on listening to your system at different times, then turn it off at night. Of course, it's always smart to turn your system off if you're leaving the house. Whether it's for a couple of weeks or just a couple of hours.

Tubes are supposed to make noise when you tap on them! If a tube is truly microphonic, and in a position where it is critical, you will know it. It will feedback as you play music and be so objectionable you'll turn it off. Replacing the tube is the only solution.

Some people like them. Others say tube dampers make the music sound sterile or hard. A small amount of microphony can be pleasing, as it can inject a sense of "air" into the presentation. This answer will vary based on the system, your taste, and the individual tube you are using. There are a number of affordable tube dampers (silicon rubber O-rings for example) on the market. You can give these a try. If you don't like the change of sound with the tube dampers, you can always take them off.

The 6DJ8/6922/7308 family of tubes is a special lot and are prone to be sensitive to vibration. That does not mean all of them are microphonic by definition, though some are. What's this mean for you? In high gain pre-amps, you may hear a slight "TING!" when flipping some switches. Usually this is caused by the grid wires picking up vibration through the tube pins.

One more helpful hint: We recommend that you have something hooked up to the output of any tube product when they are turned on. This applies to pre-amps, amps or anything else. If a tube preamp is left on for an extended period without being hooked up to a power amp, mute it.

Each tube, even when produced in the same batch, has some slight differences in its cathode current. Some amplifiers are required to match these tubes to give the best sound. PrimaLuna’s are designed with Adaptive AutoBias. This means that it is not necessary to match power tubes in your amplifier because the device itself will compensate for the differences. However, matched tubes will be easier on your amplifier. Also, some users experience a different/better sound. This is up to you to experiment with.

No, there are many tubes with the same pin layout. Check the manual of your device to see which tubes can be used, or even better, visit and ask in the PrimaLuna Owners Group: https://www.facebook.com/groups/509067122811946/  

It is possible to replace only the dead tube with a new one. The Adaptive AutoBias inside your PrimaLuna will ensure the device performs as expected. However, there can be a change in sound because of this change. Also, consider when one tube dies, others can follow because of the same lifespan. Because of this, we often see that consumers replace all tubes with the same function. That also gives you the opportunity to have the old tubes tested, and keep the good ones as spares.

You may have a bad power tube that blew the plate fuse. Read your owner's manual for detailed instructions on how to check the plate fuse. You can also download the owner's manual from this site.

Attention! If, for whatever reason, the HP/LS switch has been switched to HP (headphones), you might also have the impression that it is defective (because you don't hear the loudspeakers). Turn down the volume, switch the HP/LS switch in the LS position, and turn up the volume to listen to your loudspeakers.

You may have blown the mains fuse. Many factors could cause this, including a power surge or spike in your home. Replace the fuse and turn the amp back on. Read your owner's manual for detailed instructions on how to check the main fuse and to find the appropriate value. You can also download the owner's manual from this site. It's important to install Littelfuse 213 Serie fuses. For the correct value, check for the current Fuse Table (V 10.5 at the moment of writing – 2024-02-10).

It might be that the tube has a problem. Sometimes, though, it indicates a non-perfect contact between pins and tube socket. By taking out the tube and re-inserting it often “repairs” such an issue. Also, to check if the tube is still okay with a tube tester is a good idea. The fact that the LEDs in front of the power tubes sometimes light up at by switching the amplifier on and/or off, isn’t a problem.

You can buy a spare PrimaLuna remote or any available brand learning remote. However, it is also possible to replace the faulty switches under these buttons. Switches used are OMRON switches, and more information can be found here: https://nl.farnell.com/omron/b3f-1000/switch-spno-0-05a-24v-tht-0-98n/dp/176432?ost=176432. This is the Dutch division of Farnell. In other countries other suppliers are around. Omron is available worldwide.

For the “handyman", it’s not too difficult to cut out the volume + and volume – switches. These are used the most, of course, and sometimes pushed harder than necessary. Once you cut off the switch, desolder and remove the remaining legs of the PCB and clean the mounting holes, install the new switches, and resolder. Ready. 

In case your remote doesn't function anymore at all, check the battery and check this link: https://primalunablog.com/2016/08/03/help-my-remote-control-is-out-of-control/ and your manual.

All PrimaLuna equipment comes with a two-year warranty that covers parts and labor. Tubes are guaranteed for six months only. This warranty is basically for the original purchaser only and is not transferable to subsequent owners under any circumstances, however different countries have different laws. Of course, local laws "rule".

This depends on the situation. As long as tubes with the same specifications are used and changed according to the manual, the warranty on your product will not expire. The warranty on your product expires if the product has not been used according to the instructions in the products manual, or if it has been misused, abused, damaged by accident or neglect, or in transport once in possession of the purchaser. The warranty is also void if the product has been tampered with or repaired or modified by anyone other than Durob BV or its specifically authorized representatives.

The Home Theater input on the DiaLogue Series is a direct-line pass-thru circuit. If you plug in a component that does not have a volume control, you may seriously damage your speakers. It is essential to ensure you only plug a home theater processor or receiver into that input. Never change any connections with any equipment switched ON. PrimaLuna, your distributor, and its partners are not liable for any damage caused by plugging an inappropriate component into the Home Theater input. If you are still determining what can and cannot be used, consult your PrimaLuna dealer or contact your distributor directly.

With so many people having home theater systems, they are used to preamps that have a subwoofer out. In a regular stereo amp with no surround processing, you see something marked subwoofer out. It typically means it is a preamp out. In essence, it is nothing more than a voltage signal coming from the preamp, fed to the woofer's amp, that is then amplified.

So, what happens if you don't have a preamp out? Almost every subwoofer made in history is designed to handle that. They have a high-level-in hooked up to the speaker taps of your amp. Works the same way. It takes the voltage from the amp as the signal and amplifies it.

This does not cause a power draw on the amp you hook up to. It uses the signal, not the amp's power, to make sound. So, there is no "draw" or sapping of power. There is no negative effect on the sound of the main speakers.

The most known subwoofers in the industry are made by REL in England. Though they can be installed either with line or speaker levels, most REL woofers are hooked to systems with speaker leads of amps. Always check out what your subwoofer manufacturer recommends!

No, the Littelfuse 213 fuses are special fuses that, for a calculated moment, can absorb the switch-on current. A Littelfuse 213 0.5A will hold longer than a standard slow blow 0.5A fuse. This means that if the tubes get a little older or after some use, they will start to draw a little more current, the “normal” slow blow might break, while the Littelfuse 213 0.5A won’t. Also, life might become a little harder for the tubes if a non-Littelfuse is in use. Always check our most current Fuse Table (at this moment of writing that is V 10.5).

If you want to replace the Littelfuse fuses for whatever brand of audiophile fuse, remember to inform the supplier that your amplifier uses Littelfuse 213 fuses. He should know that the value he supplies you with, might need to be a bit higher (or it might burn immediately after installation or soon after).   

The heat given off by the tubes travels upwards, and we recommend ensuring enough space above the amps to allow the heat to dissipate properly. In the PrimaLuna Owners group on Facebook, several members share their situation and sometimes their solution if they feel that's necessary: https://www.facebook.com/groups/509067122811946/

The PhonoLogue Chassis is a dedicated cabinet for the optional PhonoLogue MM Board. Phono circuits are susceptible to all kinds of outside interference influences. That's why the better phono stages always come in a separate, shielded chassis. Your PrimaLuna automatically comes with such a dedicated chassis. You must only add our optional Phono board (MM only) to own a "stand-alone" phono stage. 

If you own any of our older Integrated amplifiers or Preamplifiers, you can attach the belly-mounted chassis under the amplifier, but it needs a little extra work. Special instructions are available.

Our PhonoLogue Stage can be installed anytime by your dealer or any qualified technical person. Some soldering is required.

The PhonoLogue MM phono stage with RIAA equalization takes the place of the AUX2 input.

As a manufacturer, we have almost always all models in stock (or in production) in our Asia warehouse. Most of our distributors also try to hold all models in stock, but, as you will understand, they don't stock our quantities. Next, goods can always be "on the way" to them. You can find a dedicated "Stock- Status" page on our website (Stock Status) showing which products are in stock in our Asia warehouse and / or in production. For local supply, please get in touch with the local distributor (Distributors) for more information. The stock at the distributors and dealers can vary.

Please check the switch on the right side of the amplifier and make sure the button is on HP (Headphone) instead of LS (Loudspeakers). Only use this switch with the volume off. If this switch is correctly selected and there is still no sound, please contact your dealer.  

We do not recommend the use of a speaker selector box. Between the switching of the speakers,  the load on your amplifier can drop and cause damage to your amplifier.