Monoprice Monolith Liquid Platinum - By Alex Cavalli
Sep 14, 2020 at 8:31 PM Post #3,256 of 3,883

ksorota

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So according to present forum consensus, which are the bestest of best 12AU7 tubes for the LP, modded and/or unmodded. I am only referring to present reigning contenders for the title of "best." I know that such contenders could change at any time with ongoing/future tube research and discoveries.

BTW, in case this matters, I like my sound to be airy, detailed, and well-extended at both ends, without any harshness or fatigue. Thick and creamy mids are also welcome, but their absence is not a deal breaker, as long as those mids are not "thin."
Easily the best tubes I have heard are the 7730’s in various configurations (halo, D, long or short plate)
They have a presentation that i think is best described as cinematic. It’s extended and airy as you desire but are not really very thick in the mids. They produce a very wide soundstage that brings the LP to another level. Not the strongest bass, but clear and satisfying.
 
Sep 18, 2020 at 1:04 PM Post #3,257 of 3,883

Mudshark

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I bought an LP on launch back in 2018. It gave up the ghost last week while I was listening. I heard a pop in the cans I was using and the amp went dead. A chemical-like burning smell emanated from the inside of the amp.

I just received a replacement LP from Monoprice (great service!). I had been thinking of selling it NIB, but then I saw some posts about mods for the caps and volume pot, and other posts indicating that there have been some design changes to the stock pot. What if any differences should I expect between an original LP and a current production version? Thanks.
 
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Sep 18, 2020 at 1:17 PM Post #3,258 of 3,883

LCMusicLover

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I bought an LP on launch back in 2018. It gave up the ghost last week while I was listening. I heard a pop in the cans I was using and the amp went dead. A chemical-like burning smell emanated from the inside of the amp.

I just received a replacement LP from Monoprice (great service!). I had been thinking of selling it NIB, but then I saw some posts about mods for the caps and volume pot, and other posts indicating that there have been some design changes to the stock pot. What if any differences should I expect between an original LP and a current production version? Thanks.
Personally, I've had 3, and never heard any significant difference between them -- certainly nothing 'major'. I do think the volume pot on my current amp tracks better at low volume than my first one did. Doesn't matter much to me though as I just set the amp volume to 12 o'clock and use a passive preamp to attenuate.

I do think the caps mod was an improvement, but since I couldn't A/B before and after, my opinion probably carries little autorità.

.
 
Sep 18, 2020 at 1:33 PM Post #3,259 of 3,883

ksorota

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I bought an LP on launch back in 2018. It gave up the ghost last week while I was listening. I heard a pop in the cans I was using and the amp went dead. A chemical-like burning smell emanated from the inside of the amp.

I just received a replacement LP from Monoprice (great service!). I had been thinking of selling it NIB, but then I saw some posts about mods for the caps and volume pot, and other posts indicating that there have been some design changes to the stock pot. What if any differences should I expect between an original LP and a current production version? Thanks.

I do not think that their has been any update or change to the stock volume pot. All the units that I have opened up have included the same stock pot from the original release cycle. The changes people are referring to are related to volume matching between channels. Their have been mixed experiences...some have very poor volume matching at low listening levels, almost all seem to have some level of channel imbalance at the lowest volumes, but it is not always an issue. It would have been nice if monoprice woud have used a higher quality pot, but it was not meant to be. At regular volumes most sound just fine.

Differences between the OG and newer production should not be discernible but it would be a good idea to run it a bit to make sure your volume pot has good channel tracking. Be a better value for the buyer if you can verify.
 
Sep 18, 2020 at 1:48 PM Post #3,260 of 3,883

Mudshark

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Thanks for the replies, @LCMusicLover and @ksorota. My primary concern is that my original LP went up in smoke suddenly after only two years of relatively light use, the entire time plugged into a Bryston BIT-20 power isolation transformer. Monoprice did not ask any questions when I reported the problem and they sent me a prepaid shipping label to send the amp back to them via FedEx Priority Overnight. The amp traveled @ 2,900 miles -- from Northern New England to Rancho Cucamonga, California -- in less than 24 hours. I deduced from all this that Monoprice is likely familiar with whatever it is that cooked my original LP. I hope that whatever it was has been remedied in current production models.
 
Sep 18, 2020 at 2:19 PM Post #3,261 of 3,883

Skooks

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I have put about 200 hours on my Liquid Platinum Headphone Amp with the LPS-36 Linear Power Supply. I can happily report that my headphone system is sounding GREAT... not one single problem! As I said before, it has a silent background and transparent presentation. It is the BEST sound I've had with a headphone system!
But, let me also say one more time, because I think this is very important in using the LPS-36 with the LP...

• Each time when starting up, I first push the startup button on the LPS-36 and let it bring the tubes up. I watch the red LED on the LP go from red to white... then, I push the startup button on the LP and let it warm up before playing music.
• When powering down, first turn the LP off with its power button... then, turn the LPS-36 off with its power button.

This is very important for safe operation with the LPS-36.

BTW... this is my 2nd mod of the LP. My first was the caps mod.

Enjoy!
 
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Sep 18, 2020 at 2:42 PM Post #3,263 of 3,883

sahmen

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I have put about 300 hours on my Liquid Platinum Headphone Amp with the LPS-36 Linear Power Supply. I can happily report that my headphone system is sounding GREAT... not one single problem! As I said before, it has a silent background and transparent presentation. It is the BEST sound I've had with a headphone system!
But, let me also say one more time, because I think this is very important in using the LPS-36 with the LP...

• Each time when starting up, I first push the startup button on the LPS-36 and let it bring the tubes up. I watch the red LED on the LP go from red to white... then, I push the startup button on the LP and let it warm up before playing music.
• When powering down, first turn the LP off with its power button... then, turn the LPS-36 off with its power button.

This is very important for safe operation with the LPS-36.

BTW... this is my 2nd mod of the LP. My first was the caps mod.

Enjoy!

I just need to make sure I am getting this correctly. If the LPS start up button should go on first, fire up the tubes and the LP's led from red to white before one may start up the LP itself, then it means that the tubes and the LP's led can be started and whipped up to readiness even with the LP itself off (with the power-on push button of the LP in the "off" position). Or put differently the LPS-36 can independently activate the tubes and the LP's Led without any help (or power) from the LP?... I am asking because this is important, as I just received my LPS-36, and I am about to try it on the LP. Besides, I am a little surprised by this, if your post is saying what I think it is saying.

Let me know.
 
Sep 18, 2020 at 2:47 PM Post #3,264 of 3,883

sahmen

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One more thing of interest to some... my wife tweaking project is coming along, but not without a few glitches! If you try this tweaking, do so with utmost caution! :stuck_out_tongue_winking_eye:

Or just don't try this at home :relaxed: :relaxed: :relaxed:

GivingGloomyCalf-size_restricted.gif
 
Sep 18, 2020 at 2:48 PM Post #3,265 of 3,883

LCMusicLover

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Sep 18, 2020 at 4:56 PM Post #3,266 of 3,883

Skooks

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I just need to make sure I am getting this correctly. If the LPS start up button should go on first, fire up the tubes and the LP's led from red to white before one may start up the LP itself, then it means that the tubes and the LP's led can be started and whipped up to readiness even with the LP itself off (with the power-on push button of the LP in the "off" position). Or put differently the LPS-36 can independently activate the tubes and the LP's Led without any help (or power) from the LP?... I am asking because this is important, as I just received my LPS-36, and I am about to try it on the LP. Besides, I am a little surprised by this, if your post is saying what I think it is saying.

Let me know.
You have it right... firing up the LPS-36 does put power to the LP and the red LED comes on along with the tubes lighting up... and after a few minutes the LED goes from red to white, but music will not play until you completely turn on the LP by pushing its power button.
 
Sep 18, 2020 at 5:45 PM Post #3,267 of 3,883

povidlo

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Need help please :slight_frown::
having an issue running LP with my AK SR25 dap. Using 2.5mm to XLR cable, the sound is distorted. When muted and turning the knob past noon, there's a loud buzzing noise through either SE or BAL output. It's louder through BAL output.

Tried reducing line-out on the dap from 4V to 2.5V but it didn't make a difference. As soon as the cable is plugged into the dap, buzzing occurs. It gets worse once the screen is turned on.

It doesn't happen when connecting the dap to LP with 3.5mm to RCA cable.

So thought it's a faulty cable, or maybe faulty BAL input on LP. But used the same cable with 4.4mm to 2.5mm adapter and connected Paw S1 to LP, and no buzzing.

Also, daisy-chained SR25 2.5mm to 2.5mm to iFi xCan and then the same 2.5mm to XLR cable to LP, and no buzzing.

Same buzzing noise can be heard if the 2.5mm to XLR cable is not connected to any device and 2.5mm connector is out.

Maybe some sort of a grounding issue? It doesn't make sense to me that straight SR25 to LP connection doesn't work. SR25 seems to have a quality 4V output on balanced and I haven't observed this issue stacking it with an amp in 2.5mm to 2.5mm way.

This cable: https://www.aliexpress.com/item/4000159895454.html
 
Sep 18, 2020 at 9:47 PM Post #3,268 of 3,883

wormsdriver

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Need help please :slight_frown::
having an issue running LP with my AK SR25 dap. Using 2.5mm to XLR cable, the sound is distorted. When muted and turning the knob past noon, there's a loud buzzing noise through either SE or BAL output. It's louder through BAL output.

Tried reducing line-out on the dap from 4V to 2.5V but it didn't make a difference. As soon as the cable is plugged into the dap, buzzing occurs. It gets worse once the screen is turned on.

It doesn't happen when connecting the dap to LP with 3.5mm to RCA cable.

So thought it's a faulty cable, or maybe faulty BAL input on LP. But used the same cable with 4.4mm to 2.5mm adapter and connected Paw S1 to LP, and no buzzing.

Also, daisy-chained SR25 2.5mm to 2.5mm to iFi xCan and then the same 2.5mm to XLR cable to LP, and no buzzing.

Same buzzing noise can be heard if the 2.5mm to XLR cable is not connected to any device and 2.5mm connector is out.

Maybe some sort of a grounding issue? It doesn't make sense to me that straight SR25 to LP connection doesn't work. SR25 seems to have a quality 4V output on balanced and I haven't observed this issue stacking it with an amp in 2.5mm to 2.5mm way.

This cable: https://www.aliexpress.com/item/4000159895454.html
Ak daps need (or is recommended) to use the 3.5mm socket on the dap as ground. You need a cable like this:
Screenshot_20200918-204709.png

Edit: the ground sleeve of the 3.5mm is connected to the ground of the 3pin xlr jacks
 
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Sep 18, 2020 at 11:02 PM Post #3,269 of 3,883

povidlo

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Ak daps need (or is recommended) to use the 3.5mm socket on the dap as ground. You need a cable like this:
Screenshot_20200918-204709.png
Edit: the ground sleeve of the 3.5mm is connected to the ground of the 3pin xlr jacks

Much appreciated!

Contacted the seller on Ali and they will ship me a replacement cable that includes a dedicated 3.5mm connector for grounding.
 
Sep 19, 2020 at 4:03 AM Post #3,270 of 3,883

Zulkr9

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Man the failure rates are whats keeping me from purchasing this amp. Also I wanted to know whether buying open box is a good idea, I heard that there is a chance that accessories might not be present, so if I do get one is there a chance that I might not receive the adapter or something like that, tempted to get the open box, going for a really good price
 

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