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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
4.2 ★★★★★
Based on 22 reviews
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Product Reviews
★★★★★ 3
Not Hydrating Enough
Style: Updated Formula
Non greasy but is not moisturizing enough for my dry eczema prone skin.
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Reviewed in the United States on May 23, 2026
★★★★★ 5
Miracle cream
Size: 13.5 Ounce (Pack of 1)
I have been having crazy acne due to a severe reaction to salicylic acid, among other things. My face was incredibly inflamed, itchy, sensitive, red and painful. My dermatologist started me on an oral antibiotic and a clindamycin/benzoyl peroxide topical. The topical was still drying me out quite a bit so I got this lotion and it's literally a miracle cream. My skin is hydrated, no itchy or stinging and the redness has gone down so much. It's also helping my open sores to heal more quickly. Yes, it's a combination of all 3 products working together but I can definitely see and feel the cream repairing my skin barrier. I will be starting on accutane after a month of antibiotics and will continue to use this balm to keep me from drying up like a prune.
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Reviewed in the United States on May 6, 2026
★★★★★ 5
Works amazing! My eczema is clearing up on my face!
Size: 13.5 Ounce (Pack of 1)
I've been struggling with eczema all of my life and I'm insanely sensitive to all sorts of creams. I've tried just about everything you could find. Colloidal oatmeal ones...to hypo allergenic creams in high end stores. I react to goat's milk and even ones with no fragrance. Well, for the first time ever, I found a cream that seems to be doing the trick. I'm on meds to help with the eczema, but the issue was the eye area, upper forehead [between eyebrows], and right under the nose and around the lips. I'd always get this redness and it didn't matter what creams I used. I recently switched to a Clinique soap [more like a moisturizer that comes out of a bottle] for my face, but it still wasn't getting better. It helped, but the redness wasn't going away!
I read online about this cream. I don't use a ton. I put literally a drop under each eye and gently tap it into the area. I also just dab a tiny amount on any other red spot. I'm primarily using this for areas where the redness won't go away. Well, three days after starting this my skin is FINALLY healing around my eyes and in the other zones. My mom even noticed!
I can tell you, this is a THICK cream. It's too heavy to slather all over your face. Use it to target areas and use a lighter moisturizer [Aveeno has a sensitive face cream that's new and works]. This cream will help the skin heal [all those annoying patches and redness]. It's worth the money. I suspect it's going to take me ages to finish this bottle off. But, it just is so nice to see my face and not have some sort of weird raccoon look.
FYI - I do have some patches on my legs which I glob it on and it's helping that heal too. If you need a good hydrating cream that helps protect the skin and helps it get over that bump where it's irritated, this may work for you. Oh, it has absolutely no scent - none. That was a nice surprise. It's designed for sensitive skin. Initially, I was worried about the cost, but now that my eczema is healing up, it's worth every penny. This worked better than all those steroids and hydrocortisone my docs kept giving me. I was so stressed over the wrinkles under my eyes and for once, it's looking nice. :)
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Reviewed in the United States on January 24, 2023
★★★★★ 5
Amazing!! Redness and itchiness gone after 1 day!
Size: 6.76 Ounce (Pack of 1), Size: 6.76 Ounce (Pack of 1)
So, I've had really bad rashes around my eyes and cheeks for a few years. The doctors can't tell me what it is but just used to prescribe me steroid cream which thinned my skin and gave me eye wrinkles. I read about this in a post on Pinterest and ordered it immediately as I had a recurring rash on my face for 3 weeks that kept coming back. Yes it's $32 but I was DESPERATE. Everything else I tried burned my face, even products with the eczema association seal! I was so excited when this came in the mail. I was tiding myself over with Clinique's Dramatically Different Moisturizing Cream and yes, it hydrated my dry face but it stung on contact a bit, and also made my skin tight and began to peel, not painfully but still gross.
So I finally got a chance to put this xeracalm product on my face last night. I put about a quarter size amount at first, then two extra pea sized amounts under my eyes. Unfortunately through the night my face soaked it all up (my skin is EXTREMELY DRY and it's winter now) but as soon as I woke up and look in the mirror my redness was 90% gone. My face was a little tight but not uncomfortably, and definitely no peeling. It also does not burn on contact which is so great for me.
It's called a balm but it's really more like a heavy thick cream. The top is interesting as you just squeeze it and it pops out and dispenses product to not contaminate it. If you have a problem with the dispenser you have to be an idiot, I just have to be honest lol. It's not rocket science. It serves a very important purpose. Also, I was surprised at the size. $32 seemed pricey but for the amount of product I got it is totally appropriate. I only see myself using this for when my skin gets REALLY DRY and not for regular use though. And a little goes a long way. I'm hoping to see my face go back to normal in a few days. I will definitely update!
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Reviewed in the United States on November 29, 2016
★★★★★ 5
This is SO helpful for Dyshidrotic Dermantitis
Size: 6.76 Ounce (Pack of 1)
I have dyshidrotic dermatitis and this helps me with the dryness and itchy feet. It is pretty greasy but I have to keep socks on so I don't care. It works the best if you use it twice a day but still works well once a day.
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Reviewed in the United States on May 21, 2026