Jump to content

AMB Labs M3 headphone amp.


Recommended Posts

Item: M3 AMB Labs Headphone amp and 24v supply
Location: Brisbane
Price: $450 $380
Item Condition: Very good
Reason for selling: After a long search have finally settled on my "perfect" setup
Payment Method: Pickup - Cash, Paypal, COD Only

Extra Info: 

It's been many a year since I ventured into the land of headphones and the DIY journey has been filled with wonderful discoveries. It's time to release some of these into the wild for others to enjoy. All these are at below parts cost and have been built and modified and modified again to obtain what I believe is their best sound.

 

AMB Labs M3. This is where my DIY journey began. Fitted with some genuine OPA627AP opamp (@ over $45 each) which can be "rolled" to give a different sound signature. All the other component are of the highest quality, this was a no holes barred build. This amps has served me well through several sets of headphones beginning with some HE-500 of which it could drive the pants off. Here are some of it's technical highlights. And more can be found here https://www.amb.org/audio/mmm/. Amp comes with a ultra low noise 24v power supply.

 

3-channel active ground topology

In addition to the left and right channels, in this amplifier the "ground" wire of the headphone is actively driven by a third channel of the same topology. The ground channel amplifier sources or sinks the return current from the transducers, which would otherwise have been dumped into signal ground or power supply ground. This shifts responsibility for the high current reactive load of the headphones from signal ground to the tightly regulated power supply rails, thus removing the primary source of signal ground contamination. The headphone transducer "sees" symmetrical output buffers with equal impedance and transfer characteristics on both sides, rather than an output buffer on one side and a capacitor bank of the power supply ground on the other.

 

High performance opamp voltage gain stage and high current discrete MOSFET output stage

A high performance IC opamp is used for voltage gain duty in the M³ amplifier, while the discrete power MOSFET output stage provides the current gain to drive the headphones. This separation of functions isolates the headphone load from the opamp and allows it to operate without strain. Both stages operate in class A for unparalleled linearity. The MOSFET output stage has enough output power capability to drive efficient speakers to reasonable volumes.
 

Capacitance multiplier for opamp power

The power supply to the opamps is further isolated and stabilized with a complementary capacitance multiplier. A capacitor is kept charged by two JFET current sources at each side, whose capacitance is then multiplied by the DC current gain of the complementary pass transistors to provide very low noise, low impedance DC rails to the opamps, unperturbed by the MOSFET supply rails.
 

Precision virtual ground reference

Rather than using a conventional split power supply with positive, ground and negative outputs, the M³ amplifier uses a single supply and internally synthesizes a virtual signal ground by using the TLE2426 precision rail splitter chip. This simplifies the power supply requirement, yet provide the advantage of a dual-tracking split supply without associated complexity. The result is improved common-mode rejection ratio (CMRR).
 

Adjustable JFET cascode current source

The opamp for each channel is biased to operate in class A by a pair of discrete cascoded JFETs. This prevents the opamp's output transistors from ever cutting off, eliminating crossover distortion. The amount of current flowing through the JFET cascode is adjustable via a trimpot.
 

Adjustable MOSFET bias

The MOSFET bias is controlled by a VBE multiplier transistor and the quiescent current is adjustable via a trimpot to suit individual needs.
 

Fully direct-coupled

There are no signal-degrading coupling capacitors at the input, output or negative feedback loop. 

This is a true DC amplifier. The precision FET input opamps keep the DC offset very low, but care must be taken to ensure that the input source does not have DC offset at its output.
 

No input or output protection

The rugged and stable MOSFETs allows the simplest of output circuitry, providing maximum sonic transparency.
 

Optional bass boost feature

At the builder's option, a bass boost feature (either via an on/off switch or a continuously variable adjustment) can be installed to compensate for poor recordings or headphones without sufficient bass response.
 

Board-mounted premium potentiometers

The circuit board is designed to accommodate ALPS RK27 "blue velvet" or Noble AP25Y audio-grade dual-gang potentiometers for excellent inter-channel tracking. They are directly mounted onboard for the shortest signal paths to minimize crosstalk and interference.
 

Ground plane

Low impedance ground plane over low level signal areas provides shielding against interference, reduces crosstalk, and allows optimized component arrangement on the board.

High-current, superimposed power buses for MOSFET power

Wide "power plane" traces provide a low impedance path of DC power to the MOSFETs, with reservoir capacitors located immediately adjacent to the MOSFET banks.

 


 

ELECTRICAL DISCLAIMER
This product has not been manufactured by a qualified individual or company, therefore contains electrical circuits that do not necessarily comply with Australian Standards. I understand that as the seller, I may be liable to repercussions in the event of equipment failure. By advertising and selling this product, as the seller I also agree that I am solely liable, and the publisher of this website takes no responsibility for any injury or death resulting from, whether directly or indirectly, any accident that may happen as a result of the failure of the product being sold. If in doubt, seek the services of a qualified electrician to inspect the product to ensure it is safe for use.
 

 

IMG_0747.jpg

IMG_0749.jpg

IMG_0750.JPG

IMG_0752.jpg

IMG_0753.jpg

IMG_0754.jpg

IMG_0756.jpg

Edited by Benjet
Price drop
  • Like 1
Link to comment
Share on other sites
  • 2 weeks later...
  • 1 month later...
Guest
This topic is now closed to further replies.
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By muzzagruzz
      Item Condition: Excellent Shipping Options: Shipping is available at agreed cost. Suburb or Town: Miranda State: NSW Payment Method: EFT Reason for selling: NLR Further information:
      Free delivery in Sutherland Shire LGA! 

      This has the balance of five years warranty. 
       
      Selling this beautiful, as new, VPI Prime turntable that I purchased in August 2018 from Krispy Audio. 
       
      This is a supremely quiet turntable that extracts every detail and nuance from vinyl recordings. The motor is dead quiet and spins the heavy 10kg platter very quickly and accurately. 
       
      Beautifully made as with all VPI Industries turntables. This example is in as new condition - no marks or scratches anywhere to be seen as I look after my equipment. 
       
      Technical specifications: 
       
      Chassis Composition: Vinyl Wrapped MDF and Steel
      Platter Type & Size: 12" Aluminum, 20lbs
      Tonearm Included: JMW-10-3D Tonearm
      Motor RPM: 300 RPM (this could be 600 RPM in Australian examples?)
      Motor Pulley Accuracy: +/- .0005"
      Wow and Flutter:  .05%
      Speed Accuracy:  .05%
      Rumble: 80 db Down
      Footprint: 19 ½" x 13 ¾"
      Overall Size: 21 ⅜" x 15 ¾"
      Total Weight: 44lbs
       
      Comes with all inclusions: record clamp; instructions; box
       
      Cartridge and Nordost tonearm cable in the photos not included. 
       
      Photos:
       
      PLEASE READ
      If you include any reference to pricing whatsoever in this section (excluding RRP), your ad will not be approved If you are advertising multiple items, you must post one bulk price only, or post seperate ads for each item If you don't include photographs of the actual item being sold, your ad will not be approved You understand that a reasonable donation for selling fees is expected upon successful sale of your item
      - if you have previously sold items and not made a donation, your advertisement may not be approved.













    • By muzzagruzz
      Item Condition: Mint Shipping Options: Shipping is available at agreed cost. Suburb or Town: Miranda State: NSW Payment Method: Cash EFT Reason for selling: NLR Further information:
      Purchased new by me from Addicted to Audio to store my Focal Elear headphones. I stuck the headphones in them and shoved it in a draw and that's basically where it stayed. 
       
      Perfect condition, no marks. 
       
      Comes with original box. 
       
      Photo with headphones for illustration only. Not included in the sale (just in case you were wondering). 

      Photos:
       
      PLEASE READ
      If you include any reference to pricing whatsoever in this section (excluding RRP), your ad will not be approved If you are advertising multiple items, you must post one bulk price only, or post seperate ads for each item If you don't include photographs of the actual item being sold, your ad will not be approved You understand that a reasonable donation for selling fees is expected upon successful sale of your item
      - if you have previously sold items and not made a donation, your advertisement may not be approved.








    • By foryou
      Item Condition: as new Shipping Options: Pickup available but audition is not available.,Shipping is available at agreed cost. Suburb or Town: Doncaster State: VIC Payment Method: Paypal (via F&F or buyer pay paypal fees ) , EFT, Cash on Pickup Reason for selling: fund for new amp Further information:
       
      McChanson 6L6 Tube amp
      bought new form Eric last year
      some special order with this amp
      Silk Output Transformer and Duelund cable for speaker output
      mono design with two mono volume pot (  TKD P-2511 100K MONO Attenuator  X 2 )
      mundorf supreme silver gold oil 0.47uf X 2
      speaker output 8/16ohm but you can change it to 4ohm /8ohm
       
      Ultra Linear / Triode (SET) switchable with adjustable fixed bias
      Two RCA input
      mainly use it as Power amp with Tannoy / Lowther speaker
       
      come with syetlans 6550c X3 and RCA 6L6  , 2 set of input tube , also rectifier tube
      10w-12w power ouput for 6L6 tube
      but if you use Kt66/Kt88 or Kt90 the power will increase

      Photos:
       
      PLEASE READ
      If you include any reference to pricing whatsoever in this section (excluding RRP), your ad will not be approved If you are advertising multiple items, you must post one bulk price only, or post seperate ads for each item If you don't include photographs of the actual item being sold, your ad will not be approved You understand that a reasonable donation for selling fees is expected upon successful sale of your item
      - if you have previously sold items and not made a donation, your advertisement may not be approved.









       
    • By studer30
      Item Condition: Used Shipping Options: Shipping is available at agreed cost. Suburb or Town: Brisbane State: QLD Payment Method: Money Reason for selling: Thinning the collection. Further information:
       
      On offer is  Aiwa AD-F990 cassette decks. Comes one T200 remote. These were optional extras but come as part of the sale. 
       
      The decks themselves function very well and are a technical tour-de-force featuring the following functions:
       
      Amorphous Tape Heads and dual capstans Automatic Tape Calibration Automatic Tape Type Selection Automatic Record Level Setting Built in demagnetizer Real time and Linear tape timer Dolby B and C Dolby HX Pro Automatic NR Detection (Deck automatically detects and switches to the type of NR used on the tape ) Large format Fluorescent Display Full Logic Transport Controls and more.  
      Here’s a good place that gives a run down on these wonderful sounding machines : 
       https://www.cassettedeck.org/aiwa/ad-f990

      Was part of a collection and very gently used. Deck have been previously serviced and all belts have been replaced. All functions work when tested. The silver top has some dings on the cover. This is purely cosmetic. The deck has a full bodied sound and presentation that delivers energy when the music calls for it. Top of the line  sounding machine with a wonderful sound and plenty of convenience features.
       
      The Black version has been sold. Only the Silver one is available. 

      Photos:

      PLEASE READ
      If you include any reference to pricing whatsoever in this section (excluding RRP), your ad will not be approved If you are advertising multiple items, you must post one bulk price only, or post seperate ads for each item If you don't include photographs of the actual item being sold, your ad will not be approved You understand that a reasonable donation for selling fees is expected upon successful sale of your item
      - if you have previously sold items and not made a donation, your advertisement may not be approved.  
       
       
       
    • By foryou
      Item Condition: as new Shipping Options: Pickup available but audition is not available.,Shipping is included in price. Suburb or Town: Doncaster State: VIC Payment Method: Paypal (via F&F or buyer pay paypal fees ) , EFT, Cash on Pickup Reason for selling: fund for new amp Further information:
       
      Up for sale as New XTZ EDGE A2-300
      Huge power from this amp 
      one of the Best Buy power amp in budget 
      Perfect size and great upgrade 
      the amp still in 1 year warranty 
      If you have two of it , you can run it bi-amp as mono block
       
      Free shipping
      https://www.xtzsound.eu/product/edge-a2-300
       
      Photos:
       





       
       
      PLEASE READ
      If you include any reference to pricing whatsoever in this section (excluding RRP), your ad will not be approved If you are advertising multiple items, you must post one bulk price only, or post seperate ads for each item If you don't include photographs of the actual item being sold, your ad will not be approved You understand that a reasonable donation for selling fees is expected upon successful sale of your item
      - if you have previously sold items and not made a donation, your advertisement may not be approved.




×
×
  • Create New...
To Top