ampsandsound (aka Amps & Sound)
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Luckbad

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Mogwai



Like many of our products, the Mogwai evolved from our earlier designs, borrowing from the Bigger Ben and Classic Wonder, while embracing the form factor of the Kenzie. The Mogwai offers more than an entry point for tube amps, but a hybrid product, meant for serious headphone and speaker use.

Our circuit offers the ability to roll a wide variety of tubes inexpensively and bring increased power to headphones without any sacrifice of design choices that conflict with our values.

The Mogwai combines the features of a full sized amp into a small amplifier package, weighing ~15lbs largely due to its over spec’d custom wound transformers. The Mogwai utilizes Single ended Class A operation with zero feedback to provide the essence of our Classic Wonder sound; strictly old school SET sound, while paired with a more accessible tube selection.

The performance of the Mogwai is made possible with custom wound ultra-high quality output transformers from Transcendar Transformers providing amazing frequency extension and flat response.

The Mogwai does not use a voltage divider network, but depends on transformers instead. We chose 32ohm tap for headphones to offer a dedicated selection for the widest range of headphones, and an 8ohm speaker tap to connect the Mogwai to moderately efficient speakers.

The Mogwai displays its transformers prominently on the chassis to frame in the tube selections, which can vary from a 6L6GC to a KT88.

Volume control is handled by the ALPS volume pot to allow attenuation and simplify the signal path… no preamp is needed. Zero feedback on the outputs negates the need for a pre, an iPhone can drive the Mogwai without issue.
The Mogwai differs from the Kenzie as it aims to provide powerful output while remaining true to 50s tube ideals, and single ended sweetness. As with all ampsandsound products, we strive for a neutral, non-fatiguing sound, and demand that all our products be ultra-quiet in operation. Quiet operation is not just a goal but a guiding principle that shapes all design and implementation choices… from pots to resistors we strive for tube amps to never distract from the music.

Input tube: 6SL7 or equivalent
Output tubes: 6L6GC, EL34s, KT66, KT77, KT88, 6550s and KT90s
Personal favorite is the TungSol 6L6GC STR. Warm, strong and tight bass.
Cathode Bias/automatic bias allows for easy tube changes without adjustment.

Compatible with 32ohm-300ohm headphones using the “32ohm” 1/4″ jack. (Beyerdynamic T1-600ohm were used successfully but not ideal.)

Headphones driven successfully or tested with the amp include, Mr. Speaker Ethers, Mr. Speaker Ether Cs, Audeze LCD-2.2F, Audeze LCD-XC, AKG240, AKG701, Sony MDRV6, Sennheiser HD650, Sennheiser HD800, Beyerdynamic T1-32ohm, HIFIMAN HE400i.

The Mogwai is made with pride in Southern California with US sourced parts, including our precision transformers.

Specs:
Input impedance is 250Kohm with alps pot, .5v for full power.
Noise with pot fully counterclockwise is 500 micro volts RMS
Measured with 6550 output tubes on 1/4″ 32ohm optimzied headphone jack. 500mW RMS output 20 Hz (-2db) to 17.7 kHz (-3db)
Measured with 6550 output tubes on 8 ohm tap. 3W RMS output 30 Hz (-1db) to 20 kHz (-2db)

Please look at our news section for feedback from owners of the Mogwai.
Mogwai Headphone amp – $1,700 with tube set.

Kenzie Headphone Amp



Like many of our products, the Kenzie Headphone Amp evolved from our earlier designs – in this case, rave reviews about the SE-84’s headphone section. The inevitable question followed; why didn’t we build a dedicated headphone amp?

Why indeed? After some research, we came to the conclusion that the Kenzie amp using the much loved darling circuit was the right choice for us. The outstanding performance of the Kenzie Headphone amp is made possible with custom wound ultra-high quality output transformers providing amazing frequency extension. The Kenzie does not use a voltage network, and has more than enough power to drive even the most difficult headphones. We chose 32ohm and 600ohm to allow use with the widest variety of headphones.

The Kenzie Headphone amp showcases the transformers on the chassis to frame in the amazing 1626 tubes in all their single-ended direct-heated bliss. We have included an ALPS volume pot to allow attenuation and simplify the signal path… no preamp is needed.

The 1626 AKA Kenzie is one of the sweetest-sounding amps you will ever hear. The 1626 is commonly referred to as the poor man’s 300b; all the same great imaging, texture, and single-ended sweetness without the cost to break the bank.

The 1626 is a WWII era tube used as a transmitter tube in radar installations. The design is shy on pure output, but is overflowing with texture and drive, and is paired with a massive choke and robust output transformers for ultra-quiet operation. As with all of our products, parts selection was crucial during this build and each chosen not for price, but for best quality and synergy.

Input tube: 12SL7 or equivalent
Output tubes: 1626 or VT-137 which is a WWII transmitter tube and characterized as sounding like a mini 300b.
Cathode Bias/automatic bias allows for easy tube changes without adjustment.
Compatible with 32ohm-300ohm headphones using the 32ohm 1/4″ jack.
Headphones above 300ohms will benefit from using the 600ohm 1/4″ jack.
Headphones driven successfully or tested with the amp include, Mr. Speaker Ethers, Mr. Speaker Ether Cs, Audeze LCD-2.2F, Audeze LCD-XC, AKG240, AKG701, Sony MDRV6, Sennheiser HD650, Sennheiser HD800 (though reduced volume), Beyerdynamic T1-600ohm, HIFIMAN HE400i.

The Kenzie is made with pride in Southern California with US sourced parts, including our precision transformers.

Specs:
Input impedance is 250Kohm with alps pot, .5v for full power.
Noise with pot fully counterclockwise is 5mV RMS (Average)
All measured at 32 ohm tap. All power measurements in RMS
100mW 20 Hz (-1db) to 17.7 kHz (-3db)
150mW 20 Hz (-1db) to 14.8 kHz (-3db)
200mW 20 Hz (-1.25db) to 16.7 kHz (-3db)

Please look at our news section for feedback from owners of the Kenzie Headphone amp.
Kenzie Headphone amp – $1,500 with NOS tube set.

Gizmo

I picked up the Mogwai that was at CanJam SoCal. Really loving it! These amps deserve their own thread. I'd post a pic of it, but it's the one on the website and the pictures are way better than what I can take.

Since I bought the prototype, I'm claiming the right of prima nocta... or something... and nicknaming my Mogwai "Gizmo."


Reviews

Kenzie Headphone Amp

Positive Feedback
Headphone.Guru
mithrandir38
joespride

Note that development continues over at ampsandsound, and additional amplifiers have come to be since the post was originally made.

The following headphones amps are now being made by ampsandsound:
  • Kenzie: Based on the Darling circuit. Now has a coupling cap upgrade option.
  • Kenzie Encore: Bigger than the original, headphone jacks now up front. Now has 2 inputs and 1 preamp out. Also comes in a Deluxe version with input transformers and upgraded coupling caps.
  • Mogwai: Headphone / speaker amplifier in one, old school SET sound. Coupling cap upgrade now available.
  • Mogwai Special Edition: Not yet widely available. Includes a tube rectifier and moves the the headphone jacks up front.
  • Agartha: Uses 300b tubes, SET sound. Cap and input transformer upgrades available.
  • Leeloo: Uses 12AX7 for input and a pair of EL-84s for output.
  • NOTE: You can talk to Justin Weber and order different output impedance on the headphone jack than what's listed.
 
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Luckbad

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  What's the pricing on these babies?
 
$1500 on the Kenzie, $1700 on the Mogwai.
 
In other words, not nearly as expensive as I expected.
 
After being extremely impressed with the sound, I eventually made the butt-puckering decision to ask how much they cost. I was expected upwards of $3000.
 
When he said how much they cost, my eyes went a little wider and my heart started beating faster...
 
I made the wise decision to go try all of the other tube amps at CanJam to make sure I wasn't completely bonkers.
 
I wasn't.
 
I came back downstairs after hours of trying other gear and committed to the purchase.
 
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Luckbad

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I went to grab another tube to play with from Justin and he let me take a fun DIY project of his back with me to test the speaker taps... Whiskey Box Speakers.
 
They shouldn't sound as good as they do.
 
 
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Luckbad

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  I have the Kenzie on my short list and wondered if it was one you tried......http://ampsandsound.com/products/amps/kenzie-special-edition/
 
Yep! I was really impressed with both the Kenzie and Mogwai. Honestly the main thing that drove me to get the Mogwai was that it had speaker taps and I would be able to buy the prototype unit, which is a fun novelty. :)
 
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joespride

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I have had several of ampsandsound products and can tell you Justin is top knotch, He puts a lot of heart and soul into his builds and SQ is 2nd to none. Glad to see you started this thread luck
 
Below are links to my thoughts on a couple of Justins amps,  I am no writer (youve been warned)
 
 
http://www.head-fi.org/products/ampsandsound-se-84/reviews/10582
 
 
http://www.head-fi.org/products/ampsandsound-kenzie-headphone/reviews/14229
 
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raybone0566

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Definitely looking to here some impressions on this amp.
 
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Luckbad

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  How do you think they compare to your previous Master-11?
 
The Mogwai and Kenzie are both highly musical. It's hard to compare a tube amp with a solid state.
 
The Master-11 amp section is perfectly neutral, but it has a lot of power and can do everything you ask of it. The DAC section is more important to the sound of the Master-11's amp than the amplifier itself, as the amp isn't coloring the sound.
 
The Mogwai and Kenzie are both tube amplifiers, and both of them let you color the sound considerably.
 
I can speak better to the Mogwai since I own it now and only got to hear the Kenzie at the meet.
 
It has all of the romantic euphony of a tube amp but has balls--a power and grunt that many tube amplifiers lack.
 
It's not perfectly neutral. The highs are slightly rolled off, and sub-bass can be slightly rolled off with certain tubes as well. Different parts of the frequency spectrum can be emphasized a bit depending on the tubes used.
 
For example, the coveted Svetlana 6550 tubes sound amazing and have ample bass for me, but they have somewhere in the upper mids/lower treble that I'm sensitive to (it's the specific part of the spectrum that I'm sensitive to).
 
The JJ 6CA7 power tubes are powerful, punchy, and full sounding. They also roll the upper mids off a little, which is absolutely perfect for me.
 
I'm going to do some more tube rolling because you know... it's an addiction...
 
Tube rolling in this thing is incredibly easy. It uses an auto-bias method that I suspect is similar to the Garage1217 Project Ember in that you don't have to do anything but turn off the amp, swap in a tube, and turn on the amp. It takes care of the rest.
 
I'm trying to decide which KT88 tubes to try out in part because they have the sexy fat bottle look.
 
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Luckbad

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Here's Gizmo (the affectionate name for my Mogwai) with new production JJ KT88 and Tung-Sol GSL7GT tubes. I'm happy to report that these new production tubes are excellent and relatively inexpensive!
 

 
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ampsandsound

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Looking stout. JJ KT-88s are bass monsters. I've used in my old Dynaco MKIIIs and loved.
 
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mithrandir38

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Thanks @Luckbad for the heads up!  Looks like our threads came up around the same time: so I'm reposting here.
these are initial impressions; I'm planning on doing a full review.
 
I've been burning in the Kenzie for around a week now.  It sounded great right out of the box (probably due to those NOS 1626's.  I've found you need less burn in time with NOS tubes then, say, modern jj's or god forbid Genelex (I hate Gold Lions).  That being said, I've been going through my library of Rush 2015 remasters (which sound steller, btw! Pretty much flat transfers from the masters-very dynamic) and Joe Satriani, from the Chrome Dome set remastered by John Cuniberti: most excellent!  This is not a particulary romantic-sounding tube amp in the cliché sense of slow, syrupy, etc. Justin likes to say it's meant to emulate tube audio of the Golden Age of the 50's.  It's very smooth, yet very fast.  One of my favorite aspects of this amp is the treble; it is oh-so-smooth! sometimes my LCD-2f's could come off as slightly dry with my former Oppo HA-1.  Not so with the Kenzie; they sound better than I've ever heard them!  I was considering a Schiit Mjolnir or Decware Zen Taboo Headphone amp but i'm really loving this amp.  I took a hit on versatility, as I can't hook up my turntable or Emotiva Airmotiv speakers, but that's ok.  This is shaping up to be an awesome reference-level tube amp.  Btw: i'm running the Kenzie from a Schiit Gungnir Multibit DAC.  If anyone looks at the specs on the Ampsandsound website, don't think twice about the modest quoted output of around 200mw @ 32ohms- I don't know the circuit design details, but whatever Justin did, this amp drives the piss out of my LCD-2f's! I'm talking you'll probably never have to turn the knob past noon, and most would be satisfied between 10-11 oclock on the knob.  And it has a second dedicated jack for high impedance phones (think Beyer T1).

 
I want to give special thanks to Justin @ampsandsound
for a very pleasurable buying experience.  For anyone in the market for a new amp, I highly recommend you check out ampsandsound.  Truly great customer service and best in class warranty coverage and service.
 
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joespride

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Which tubes are you burning in the Kenzie ??  I found the best were the Hytron vt37 / 1626, and the Raytheon 2c52  (I have a huge supply of both)  anyone interested  in an audition of said tubes I would happily support Justin by circulating a set for audition. If it turned out someone wanted a set I am sure that could be worked out as well 

 
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