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Description
bass booster box Sadowsky Onboard Bass Preamp w/ Mid BoostSadowsky Onboard Bass Preamp with Mid Range Boost 4 Knob System Active w VTC SAC ELE OBOARD MB4K The Sadowsky Onboard Bass Preamp (4 Knob System) is a completely prewired system offering the same controls and the same legendary active preamp as all Sadowsky basses. This preamp is designed for installation on most J style basses with a metal control plate. On newer active J style basses with a side jack and a battery compartment, usually no
Sadowsky Onboard Bass Preamp with Mid Range Boost - 4-Knob System Active w/ VTC
SAC ELE OBOARD MB4K
The Sadowsky Onboard Bass Preamp (4-Knob System) is a completely prewired system offering the same controls and the same legendary active preamp as all Sadowsky basses. This preamp is designed for installation on most J-style basses with a metal control plate. On newer active J-style basses with a side jack and a battery compartment, usually no modification is required. On passive basses, the only required modification is to move the output jack to the side of the instrument and to make room for a battery.
The controls are: Volume – Pan (Balance) – VTC (Vintage Tone Control) – Treble / Bass – Mid Boost switch. The treble and bass controls are boost only - flat response is with the controls at their complete counterclockwise position. The preamp also features a 500 Hz mid boost that can be switched on/off with a toggle switch. The VTC control is passive, the maximum setting is a flat EQ. The further you turn the control down, the more the high end in the signal will be attenuated.
The preamp can be installed either with the included control plate or mounted through a rear control cavity in either a 4-in-line or diamond pattern. This system is not compatible with active pickups requiring anything else than a 250K or 500K volume or balance pot.
Sadowsky MB4K Onboard 4-Knob Bass Preamp Specifications:
- Prewired Onboard Bass Preamp w/ Mid Boost for Jazz style basses with a metal control plate or rear mounted controls
- Right-Hand Orientation
- Active preamp for passive pickups
- 4-Knob layout w/ Toggle Switch
- Volume / Balance / Vintage Tone Control (P/P) / Treble Bass Stack / Mid-Boost Toggle
- Push Pull function at VTC for Preamp Bypass
- Included 0.1µF replacement capacitor for the VTC module for improved treble roll-off when used with Sadowsky Soapbar Pickups
- Frequency Response 5Hz - 50kHz
- Bass: +18dB Boost @ 40Hz
- Mid Boost: +10.6dB @ 500Hz
- Treble: +18dB Boost @ 4kHz
- Total harmonic distortion (THD) 0.18% at 1kHz
- Power Supply via one 9v Battery
- Current Draw 9mA
- up to 870 hours battery life
- input impedance 1Mohm
- output impedance 1kohm
PLEASE NOTE:
- Defects or damage resulting from culpable or improper installation as well as the use of unsuitable accessories or tools are excluded from the guarantee. This includes soldering points that are too hot, wrong soldering tin and the resulting damage to the electronics and soldering points.
- When installing a Sadowsky Onboard Preamp on a MetroExpress bass without a control plate (Modern, Verdine White and M/J models), the holes in the body for the potentiometers must be enlarged. This is because the factory installed potentiometers on the MetroExpress have a smaller diameter than the potentiometers on the Sadowsky Onboard Preamp.
This preamp has screw down connectors for a solderless installation.
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.0 ★★★★★
Based on 19 reviews
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Product Reviews
★★★★★ 4
Boys’ 5‑Piece Linen Suit Set
Color: Beige, Size: 16, Color: Beige, Size: 16
I ordered this 5‑piece linen suit in size 16 in the beige color. The set includes the jacket, pants, dress shirt, bow tie, and a slip‑on tie. The outer fabric is a blend of 70% polyester, 25% linen, and 5% spandex, and the lining is 100% polyester. The material is lightweight, which works well for warm‑weather events, but the pants are noticeably thinner than the jacket. The jacket feels sturdier because of the full lining. The jacket has a peak lapel, flap pockets, and cuff buttons, and the stitching and seams are tight and even. I did notice a few loose threads, but the fabric itself was smooth with no tears or flaws. The pants have an adjustable waistband, which is helpful, but the length was too long and will need to be tailored. The overall cut of the suit seems designed for children on the thinner side.
The shirt included in my set was a pleated style rather than a plain dress shirt. It wasn’t the style shown in the product photos, and I would have preferred a standard shirt that could be worn for various occasions rather than a very formal shirt. The tie is a pre‑tied slip‑on style with an elastic band. I would have preferred a traditional tie instead. The suit arrived in good condition with no damage, and the color was even throughout all pieces. The price is on the higher end for similar 5‑piece sets. I rated it 4 stars because the jacket is well made and the set includes all the expected pieces, but the thin pants, unexpected pleated shirt, and slip‑on tie kept it from being perfect.
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Reviewed in the United States on April 16, 2026
★★★★★ 5
Adorable and Well‑Made Outfit for Special Events
Color: Light Blue, Size: 10, Color: Light Blue, Size: 10
Got this suit set for my son and absolutely love it. It comes with everything he needs to look sharp, and I really appreciate that it includes both a tie and a bow tie so we can switch up the style depending on the occasion. The quality is impressive for the price — the fabric feels light and comfortable, and the whole outfit has a polished look without being stiff or uncomfortable.
The fit was spot on, and the adjustable waistband is a huge help for getting it just right. My son looked great in it, and it’s definitely something he can wear for more than one event. The little details on the jacket and pants give it a classic, dressed‑up feel that works for weddings, holidays, or any special moment.
Overall, it’s a stylish, practical set that makes getting him ready so much easier. Really happy with this purchase.
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Reviewed in the United States on May 1, 2026
★★★★★ 4
Boys linen fabric suit
Color: Light Green, Size: 16
Boys suit set in a lighter green color. This suit is made with good proportions and seems to fit well. The sizing seems slightly big so maybe size down one size. The fabric does wrinkle easily so be aware that sitting and folding the suit may cause wrinkling. Otherwise it is a very nice suit for a formal occasion. It comes in many good colors.
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Reviewed in the United States on April 29, 2026
★★★★★ 5
Nice elegant suit for any occasion.
Color: Light Blue, Size: 12, Color: Light Blue, Size: 12
The suit set is very nice, the fabric material is durable and soft. Overall stitching is tight with nice surging of the hems and great construction on the shoulders. Buttons and button wholes are well done. I'm going to iron in the creases on the front of the pants because they weren't folded properly for shipping. The material does hold on to wrinkles so don't be afraid of your iron to get a super sharp look.
The color is a soft baby blue that stands out in a crowd of black suits. With the option of an elastic tie or clip on bowtie this is everything you need to make him look presentable for a variety of occasions.
My only complaint about this suit kit is the dress shirt is stiff and thin. I found some loose threads that I don't trust to not get played with. I'll probably trade it out for something with a little more cotton.
As far as cost goes mid range, but definitely worth the cost. I might consider something with a vest if it's a super formal event, but I'm very happy with how this suit comes together.
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Reviewed in the United States on April 18, 2026
★★★★★ 5
Modern luxury with summer fabric that performs above its price!
Color: Beige, Size: 14, Color: Beige, Size: 14
Wow! My son wore it for Easter Sunday and this suit fits the bill! The linen material is spot on--not too heavy and not too light especially since the weather is warming up now. The jacket is quality made--the design is modern executive, the stitches are strong no flaws to note. The pants are tad bit longer but that's okay, build quality is also great. The white shirt is decent and matches well with the rest of the set. The bow tie and tie itself is a great complimentary to the set, though optional to wear. The whole set just has that quality you would really look for in the price range you would want to pay. Overall, best value for for the, wear right outside the bag, maybe a light ironing otherwise it's perfect! I highly recommend it, no complaints here very happy with this suit!
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Reviewed in the United States on April 5, 2026