Frequently Asked Questions

Below are some of the most frequently asked questions we have received. If you would like to ask a question about an individual product, please do so in the "Questions and Answers" section on each product page. If you have a question that you do not see answered here, please feel free to contact us. Click each question below to read the answer.

On August 30, 2018, California changed the legal requirements for the law commonly referred to as California Prop 65. It is now required that California customers be notified prior to completing checkout of any products that contain chemicals on the list published by the State of California. These warnings are now displayed to all California customers on our review order page and prior to the final submission. For more information, please visit
This is a shipment that will be packed in a box normally, but then placed in a "UPS Pak" bag. The advantage of this method is that it prevents small, lightweight packages from being rated for dimensional weight at 2 lbs and charges for only the actual weight, so you will be paying less to ship the same box.
Yellow Jackets® converters are manufactured in the United States.
Yes! ALL Yellow Jackets have a one year Warranty against manufacturer defects.
If you are in doubt, you may e-mail and we will help you decide. YJS The YJS is for amplifiers with fixed bias power tubes. Fixed bias power tubes have their cathode connected directly to ground and a negative DC voltage applied to their control grid. The negative bias voltage is usually adjustable by way of a bias pot. YJC The YJC is for amplifiers with cathode biased power tubes. (This is often referred to as self-bias or auto-bias because it does not require a bias pot adjustment when tubes are changed). Cathode biased power tubes will have a resistor and bypass capacitor connected in parallel from their cathode to ground, as seen with most preamp 12AX7 triodes. The ground wire is used to bypass the amp's original cathode bias components so that the Yellow Jacket® converter's internal bias components are used instead. YJ20 The YJ20 is like a YJC that does not drop the plate and screen voltages. It is meant for use in lower power output amps (20W or less) when no power reduction is desired. It comes with a ground wire for cathode biased amps. YJUNI The YJUni is a direct pin to pin converter with no internal voltage dropping or bias components. It is meant for use in lower power output amps (20W or less) when no power reduction is desired and you would prefer to use the amp's original cathode bias components. YJ7591 The YJ7591 is for amplifiers that use 7591 power tubes. Only the triode version will provide a power reduction. It comes with a ground wire for cathode biased amps.
It is not necessary to use the YJC in this amp. The 1 ohm cathode resistor is for measuring bias and does not present any problems for the Yellow Jackets® adaptor internal cathode bias circuit.
No. We do not recommend using Yellow Jackets® adaptors in amps that are rated for more than 100W power output or that have more than 519V on the power tube plates.
No. The Yellow Jackets® adaptors will NOT work with cathode driven power tubes.
You may use other direct substitutes for the EL84 including 6BQ5, E84L, EL844, 7189, 7189A and 7320.
There are two ideas to consider here. 1.) A 90% power output drop does not mean a 90% drop in volume. You actually have to reduce power output by a factor of 10 (i.e. 90%) to hear half the volume. For example, a 60W amp at full volume puts out 6W at 1/2 volume, 0.6W at 1/4 volume, 0.06W at 1/8 volume, etc. 2.) The YJS Triodes in your amp have reduced the maximum power output of 60W to about 6W. If you had the amp set for 3W output power before installing the Yellow Jackets® adaptor, you will still have the same 3W output and will not notice a volume difference until you turn it up to at least 6W.
Yes. They can be used to convert class AB outputs to class A, but they are definitely good for allowing the use of EL84 tubes in Class A amps (Single-Ended or Push-Pull).
For a single-ended cathode biased 6V6GT, you can use the YJC, YJ20 or YJUni. The YJC will give you a bigger plate and screen voltage drop for more of a power reduction at high amp volume settings. The YJ20 will not drop the plate or screen voltage so that there is no power reduction. The YJUni is a direct pin to pin converter with no internal voltage drop or cathode bias circuit which means you will be using your amp's cathode bias and screen circuit.
This is a matter of personal taste. The triode version will provide a greater power reduction and is more linear (less distortion) than the pentode. If you're looking for the maximum power reduction and want to tame the response of your amp a little, then go for the triode. If you'd like a power reduction, but want a response with more bite and attitude, then go for the pentode.
The triode version provides a greater power reduction and more linearity than the normal (pentode) version. Most guitar amp power tubes are pentodes, meaning they have five electrodes: cathode control grid screen grid suppressor grid (or beam confining electrode) plate Power tube triodes like the 300B (more common to hi-fi stereo) have three electrodes: cathode control grid plate Pentodes can be wired to behave like triodes by connecting the supressor grid directly to the cathode and the screen grid to the plate through a current limiting resistor.
Several common questions about Mod Kits are answered in the frequently asked questions section of Additional help is also available at
Modkits all have troubleshooting documents available on their individual product pages. Alternatively, troubleshooting information is available on
If the getter flash has a milky white color, then it means air has leaked in and the tube is bad. Other discolorations are usually just due to differing speeds and temperatures at which the flashing was done and do not mean the tube is bad.
A blue glow on the surface of the glass, mica, or metal is fine. A blue or violet cloud within the tube structure is bad. An orange glow from the filament or cathode in the middle of the tube is normal and can vary from very bright to very dim depending on how it is covered from view by the surrounding structures. A red or orange glow on the surface of the plate is bad and is referred to as "red-plating." This is caused by setting the bias of the tube too hot.
We accept Visa, Mastercard, Discover and American Express as well as PayPal.
Unless we have identified the product by brand, per company policy we consider our supplier information proprietary and we do not release it.
We can drop ship your order directly to your customer upon request. This service is only available for US addresses. A service charge of 10% of the order total ($5.00 minimum) will apply. Please note that this fee applies to each individual drop shipment that you place.
Due to regulations, we are required to include a fully-valued commercial invoice on all packages leaving the United States.
Absolutely! We ship internationally using USPS, UPS or DHL. When you checkout you'll see available shipping methods and costs.
Yes, we ship to Canada primarily via International First Class and Priority Mail (USPS). We also ship via UPS Expedited, UPS Express, and USPS Express Mail. We do not recommend UPS Standard, as the brokerage fees are quite expensive. We do, however, provide it as an option.
We offer COD ordering via UPS. This service is subject to approval.
We do offer UPS 3-Day, 2-Day, and Next Day Air. These express services can be quite expensive; and larger packages are charged based on dimensional weight. If you do choose to have your order shipped using one of these services, please make sure you include your best available contact information (you can use the special instructions section at the end of the order).
We process and ship our orders Monday through Friday. Generally, if we receive a web order before 2:30pm Arizona time, we are able to process and ship it out that day. If you call in your order, we can usually get it out the same day if you call before 3:30pm Arizona time.
All items in our catalog are guaranteed to meet your satisfaction or they may be returned withing 10 days for exchange or credit, providing the item is in resellable condition. Any items that have leads cut, evidence of soldering or other signs of installation and/or use cannot be returned unless the product is defective Please note, opened software and cut-to-order items such as grill cloth, tolex, piping and wire cannot be returned. Defective software is returnable for exchange only. Please check and/or test your purchases upon receipt, even if the items are a back up set for future use and notify us of any problems within the warranty period. All new tubes (except horizontal amplifier tubes, also known as "linear" or "sweep" tubes) are guaranteed to meet manufacturers specifications for 90 days, except for breakage or when damaged by operation outside manufacturer's specified ratings. All used tubes are guaranteed to meet minimum industry standards for used tubes and are guaranteed for 30 days. The same exceptions and conditions as noted above for new tubes apply to used tubes. Linear/sweep tubes are guaranteed for 10 days except for breakage or damage caused by operation outside the tube manufacturer's specified ratings. Please check all linear/sweep tubes upon receitp. If there is a problem, please notify us immediately. After contacting us, we will take the tube back for evaluation by our technicians. We will notify you with a decision about our replacement or credit after the evaluation. If the linear/sweep tubes are out of the 10 day warranty period, we will not take them back under any circumstances. Should it be necessary to return merchandies for exchange or credit, email us or call with a reason for the return. Upon approval, you will be given a Return Authorization number (RA#). No returns should be made without contacting Customer Service for authorization. All returns should be sent promptly; we must receive all returns withing 30 days or the RA number will become invalid. The RA number must be placed on the outside of the package being returned in order to assure that your return is handled in a timely manner. We reserve the right to charge a restocking fee when no evidence of product failure exists if merchandise is returned after the 10-day period. Dealers and Resellers: we suggest you test all tubes and any type of electrical product upon receipt, as our warranty does not extend beyond you and ends when you resell the item.
Yes! We do accept Paypal, but only for domestic shipments.
We can match new-old-stock vacuum tubes if we have ample supply. If you request matching and we are unable to do so, we will contact you.
Most of our power tubes are matched by the Apex matching system, a proprietary, multi-step process designed to ensure that you get the highest-quality matched tubes available. We perform extensive testing and analysis on each tube that runs through our system to provide an incredibly accurate and precision-matched tube set. Discover our process for matching tubes at
We do not match dual triodes or other such preamp tubes, nor do we test for microphonics. We can match power tubes. If requested, there is a per-tube fee for matching.
It is possible that your confirmation email was blocked due to your service provider misidentifying the email as spam. Please check any bulk or spam folders you have on your email account. Additionally, you can check the status of your orders from your account page.
Please be conscientious about putting together your order. You should consider your order complete after you click the submit button at checkout. Due to the large volume of orders we receive and our extremely fast processing time, it is not always possible to add items to an order. If you have any questions or concerns, please contact us.
It is very difficult to accurately reproduce tolex and grill cloth colors and patterns electronically. If you would like a small sample to evaluate before you order, they are available. Tolex or grill cloth samples cost $1.00 each. Additionally, you can order an entire packet of the tolex samples (our part number S-GSG2) or a packet of all the grill cloth samples (part number S-GSG1).
We are constantly searching for new-old-stock vacuum tubes, and they come from a variety of surplus sources. One of our sources is our customers. If you have vacuum tubes that you would like to sell us, please request a bid list from our contact page.
For an additional $1.00 per vacuum tube, you can order specific brands of tubes. Please list any brand preferences in the comments section of your order. If we cannot fulfill this request, we will let you know
Generally our new-old-stock tubes were made by the major U.S. manufacturers, along with a small number of European manufacturers. If we have a large stock of a particular tube from a single manufacturer, we will designate the tube with its own part number. If you require a specific brand, we charge a fee of $1.00 per tube for selection.
We are not Korg. We do stock some Korg parts and we handle special order items for them. If you are looking for a specific Korg part and you do not know the Korg part number, please call Korg at 1-800-645-3188 to get the part number of the item you need. You can then call us back to place your order.
We do not offer any sort of technical assistance. Please see our tech corner for answers to frequently asked technical questions. We also have a large selection of books that can help to further your knowledge.
Once logged in, you can change your password by visiting your account page and choosing to "edit".
You will see "Open Credit" in the purchase order number box in the upper left section of your invoice.
When you place your order, we do a preauthorization on your credit card to be certain there are funds available (the amount includes the cost of the parts and a shipping estimate). The preauthorization funds are released when we perform the postauthorization, which is the actual invoice amount (the cost of the goods, the cost to ship your order and any other applicable fees.) Debit cards may take an extra day for the funds to be released. If your preauthorization has not been released, please contact your bank directly.
If you forget your password, please visit the Password Recovery Page. You will then receive an email with instructions to change your password.