Crescendo Audio


(14 reviews) Write a Review
MSRP: $1,549.99
— You save $680.00

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BassClef BC-4k

As some enthusiasts have already heard through the grapevine, it is our pleasure to announce the new BassClef series.

The current Bass Clef series has had a hell of a run since 2011, but with all good things, it is time to raise the bar once again.

The 2018 Bass Clef models range from 4kw to 17kw. The first models to hit the market will be the BC-4k and BC-6k, followed by the 8k, 13k and 17k.
All new BC amplifiers utilize a newly tooled Crescendo heatsink and revamped circuit boards that stay true to our standards, with even higher power-per-square inch and resilience than before.

Stable down to .5 ohm on sufficient electrical.
Up to 17v capable.
Newly designed, custom tooled, proprietary Multi-piece Thermal optimized Heatsink with patent pending interlocking slide-out CNC engraved top plate.
2 stage copper anodized Top Plate that is easily removable for those who want to color match to their show quality installs.
Silver plated & hard-wired Tiffany RCA inputs
2 sets of oversized 1/0 Power/Ground Inputs for efficient current transfer.
Dual 4 gauge Speaker output terminals! Which each terminal containing two outputs contains the same polarity for extreme ease of use! ( + + ) & (- -)
Overbuilt Power supply with heavy copper traces and Military spec PCB/heavy duty standoffs for extreme vibration resistance.
Handwound heavy duty transformers & inductors to insure no shorting of the windings from escessive vibration.
Manufactured using some of the highest quality and most reliable electrical components, with many 3% tolerance components throughout.
Full 4-Stage Intelligent protection Circuitry
1 Year/1ohm comprehensive warranty with 2 year/.5ohm optional extended warranty available.

Power Ratings (clean power RMS @13.8v)
1ohm: 4000w
2ohm: 2000w

Certified Amp Dyno results (on electrical consisting of Mechman 370a alternator, 8 HPL75 AGM batteries, 3 runs of Crescendo 1/0 OFC cable runs Front to back)
.5ohm: 5710w @13.1v
1ohm: 4416w @ 13.3v
2ohm: 2529w @ 13.4v


Dimensions: 23 3/4" x 9 1/8" x 2 7/8"
(25" length from tip of terminal block to RCA tip)

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14 Reviews

  • 5


    Posted by Anthony rosa on Sep 19, 2022

    Truly a piece of art, looks smooth and clean. I played it for an hour straight playing a test tone never even got to room temperature, I swear it felt cold to the touch. Best amp ever

  • 5

    Nice amp.

    Posted by Yee Vang on Feb 15, 2022

    I have this amp powering my Sundown 15 ZV5 and it amazes me how much it moves it. I had a Sundown SIA 3500 powering my sounded nice, but doesn't compare to the Bc 4k. Love it.

  • 5

    Cresendo 4k

    Posted by Adam delossantos on Dec 27, 2021

    Well built haven't hooked up yet but will soon

  • 5


    Posted by Adam Delossantos on Dec 10, 2021

    This amp is well made looks great gonna be powering a 15 inch death penalty

  • 5

    Customer service

    Posted by David Parker on Nov 27, 2021

    I ordered 2 BC4k’s about a week apart. The 1/2 was ordered with the $308 overnight shipping via UPS. It arrived after 2 days.. I know that is a shipping issues that needs to be taken up with UPS but good luck reaching a live person to talk to at UPS.. they basically force you to register online to file a claim.. As far as amp 2/2 I ordered this one with the $289 overnight saver shipping via UPS.. when I received tracking it said it was shipped out at ground and had some crazy 5 day schedule or something. I called D4S and they said they woukd have to look into it and get back with me the following day, I then noticed within the hour they tracking now said sender has requested the package to be returned to shipper. The next day I got an email with new tracking they said 2 day priority mail via USPS. ( not ups). And that they included some “freebies” to make up for the inconvenience.. I had a quote made for same weight, measurements, receiving zip code,” sent from” zip code…… it was quoted at $104. When I finally did get the amp on the 3rd day it had 1 free t shirt along with the amp………. A t shirt… I say again…. 1 freaking t shirt…. Now the main issue I have is that I paid $289 for the UPS overnight shipping. But what I actually got was a 2 day priority shipping from USPS.. Which cost around $104. Now minus 1 “t shirt” I’m still trying to figure out where the remaining about $175 ish dollars went….. bc it def went somewhere.. and it’s not accounted for when you inventory my purchase….. this is a major issue with me bc I feel like $175 was just plain takin from me. It’s fraud by definition…. Anyway buyer beware of the overnight shipping upgrade… you will get burnt everytime.

  • 5

    Bass Clef 4K

    Posted by Maximus on Jun 10, 2021

    Absolutely unreal amp! Not only is it beautiful, but it's a powerhouse! I've had it for about 6 months now. I'm currently pushing a NightShade v4.5 15, and it's unreal. My plans are to strap another bc4k and see how nasty I can get. Shipping was fast!

  • 5


    Posted by Chris on Apr 19, 2021

    No regrets very satisfied customer.

  • 5


    Posted by Ywan K Sayles on Apr 16, 2021

    Great clean power. Slowly turning it up but damn!! 1 XS D3400 under the hood & 1 in back, 390 alt & it slams like that. GREAT AMP!!!

  • 5


    Posted by pou on Dec 22, 2020

    i havent hooked it up yet but my buddy has one and it goes hard

  • 5

    Truly happy

    Posted by Carl on Mar 04, 2020

    I’ve always been big into systems. I’ve been using the same amps for the last 15 to 20 years. I decided to upgrade before my Amps turn to dust. I first purchased an Orion xtr2500.1dz and was impressed at first. Bought through amazon. Until I had issues only 3 months into usage. Orion’s customer service leaves something to be desired. Anyways. I then bought an Orion hcca 1500.4 for my highs and that amp is pretty impressive except for the internal fan sounds like it’s going to explode. So I decided to try the crescendo BC 4K from Down4Soundshop. The staff was extremely friendly and helpful. I also purchased a sundown audio 12” V2 D4 from them. The speaker is really nice but the amp is the nicest amp I’ve owned probably in my lifetime. It’s only been installed about 3 days now and I have 3 12” subs running at 2.67 ohms. Gain barely up and that amp puts out really good sounding power. It’s stayed ice cold at that impedance and still puts out power. I am extremely happy with the amp so far. I just need one more sub to make 6 12” and I’ll be able to drop my impedance and really see what the amp can do. I’m sure it will seriously impress me as it has so far. Very happy. Will purchase another soon to strap Or maybe the 6k. Very very pleased. Such a different clean powerful sound compared to the Orion. Thanks guys at Down4Sound.

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