Monoprice Monolith Liquid Platinum Headphone Amplifier by Alex Cavalli

I’ve put this together in bits and pieces but would like to clarify. Is the lineage of this amp as follows?

DIY EHHA -> Liquid Fire -> Liquid Crimson -> Liquid Platinum

I love the EHHA so this is intriguing if true.

 

In time no, but in release yes.

Actual development was

EHHA ( and other DIY) -- Cavalli goes commercial -- Liquid Fire was first release for CA --- much tinkering = liquid platinum (test bed for 25 - 50W hybrid power amp) built as headphone amp as proof of principle , sounded so good that Liquid Crimson evolved - - CA closes doors and partnerships with monoprice and Drop give rise to a few of the more affordable products available today including a scaled down version of the Liquid Platinum ( whose circuit is still near identical to crimson but balances and obviously SMD with no external fets on heatsinks )

As with all designers / developers, many concept ideas that never made it to production.

 

My power button has started making two clicking noises when I turn the amp on and off as opposed to the single click it's made since I bought it.

Likely the cheap spring used for the power button.

It still functions properly, but my anxiety that it may fail someday has gone up a bit.

 

the other clicks might be relay - iirc the power button is more of a standby activate than a switch the power on - assuming you are using the original power supply and not an LPS ?

 

The relay click happens 30 seconds or so after you start the amp, so that's a different thing.

Stock power supply.

 

There are two clicks - one when you first press the power button and one (relay) when the heaters are up to temp (~30 secs after turn-on) and amp is ready to use.

 

probably the spring if it is mechanical, hard to think why it would be doing it as it is a fairly simple mechanism.

 

I don't have the amp in front of me, but isn't the power button kind of like a pen - when you push a pen it goes "click-click" instead of just "click": It's probably OK.

 

Well, I've had the amp for over two years and it's always been a single clicking sound. So, this is a noticeable change which is the only reason it caught my attention.

Hopefully you're right. The amp has been problem free and I love it, so fingers crossed.

If not, I suppose I still have a couple years of warranty left assuming Monoprice doesn't weasel out of it at some point.

 

I got mine at launch also. no double clicky for me yet, Been Solid. Listening right now with LCD2F 2019 and Bifrost 2. I know the LCD2F and maybe even the LP aren't loved around here that much, but I love the pairing.

 

there were a few times I pressed the button, I suppose not deep enough, it did click but then it did not turn on.

I believe the button just tells the motherboard to turn on some relay. It is a little quirky since there isn't ever a problem turning it off.

I have not had monoprice give me the run around, I had bought a set of their headphones, it costed a few hundred dollars, I just described the problem outside the return period, and they e-mailed me a label and once they have received it a new one is on the way. Not that I would try to abuse such gestures as they are certainly not as automatic as some bigger e-tailer about these things.

 

The Cavalli blended hybrids with the LCD-2 or 3 and Schiit multibit is system synergy. I approve.

The Cavalli blended hybrids have a way of filling in the wonky Audeze midrange. The amps work magic. Other amps tend to remind me that the Audeze midrange is a bit recessed or off. The Fire and Platinum get the Audezes to sound right.

 

Just checked mine, and the power button double clicks. Mine is about a month old.

 

huh. I was under the impression that the liquid fire was an improved EHHA, and the Crimson was an improved liquid fire. If that’s true, and the liquid platinum is part of that family it peaks my interest because the EHHA is one of my favorite amps.

but it sounds like you’re saying they weren’t improvements but more evolutions and don’t have the same sound.

the impressions of the platinum sure don’t remind me of the EHHA.

 

You are not wrong.

The EHHA was designed as an "embedded" tube hybrid - classically hybrids are tube gain stages with solid state current gain / buffer coupled with whatever exotic capacitor is the flavour of choice. Embedded hybrids use tubes within the circuit of the gain stage and thus add a little tube character but are not the predominant element defining the sound and performance ( which is still solid state )

The EHHA used low voltage rails ~ 28V / 30V iirc and was specifically designed around the 6GM8 tubes which run optimally at a B+ of about 30V ( this is going off memory so don't judge me on details ) . This design could be scaled to offer some serious power and a few of the designs I saw added speaker taps for a lowly 10ish watts with only beefing up the power supply. The EHHA II which became the Liquid Fire changed the tube B+ to better suite the 6DJ8/6922 tubes most people were using in the EHHA and now the tubes could operate at their most linear with B+ at 100V. I actually think the amp used bipolar 100V rails given it is a true differential amp.

The evolution to Platinum / Crimson did follow on from this concept ( which is why you are not wrong ) but used the tube element in a different configuration than the EHHA/LF . The LP/LC continues the high voltage rails for the tube B+ and implemented a very nifty Low voltage rail design in which the driver section of the rails is slightly different from the high current supply for the output devices. This allows a linear swing right up to the rail voltage before any clipping etc. Alex was one very smart designer, it is a huge pity (and loss) that some of his innovative circuit designs will never truly come to light. Hopefully those few people who own one of his amps continue to cherish what they have ( even if they don't know it )

..dB

 

Well, I think I've figured out the clicking "issue".

I've used the amp in fully balanced mode since I bought it, but am in between DACs right now. So, I switched to SE inputs about a week ago and it seems the other click I'm hearing only occurs when the SE selector button on the front panel is in use.

I turned it on this morning back in balanced mode and it's back to "normal".

 

The LP is back on sale for $399.

 

Links or it didn't happen...

https://www.monoprice.com/product?p_id=33305

A few year end deals there, including the M12-S for $599
https://www.monoprice.com/product?c_id=304&cp_id=30404&cs_id=3040405&p_id=35142&seq=1&format=2

 

For anyone that's modded the LP, did you have any issues with the factory solder? It appears to be pretty high-temp. I've got my Hakko maxed out @ 899 degrees and can barely soften the solder. Tried 5 or 6 different tips as well to focus the heat better but still no go.

 

A chisel tip works the best on this for some reason, but what you really want to use is a desolder gun so that you do not overheat the board too much. The board has a very heavy ground plane and absorbs a lot of heat. Really you do not want to go that high with the solder gun...keep it under 800 degrees so you dont debond the board traces.

Make sure you have a nice clean tip, add a little fluxed solder prior to trying to soften as the solder will help in transferring the heat to the solder. The tinned tip should make it easier to get the solder on the board to flow, and then remove it.

Best of luck