PSA: Monoprice Stage Right 15w Tube Amp ~$190

vigilante398 said:
So I bought my 15W a few months ago and I've plugged it in like twice, it's just been gathering dust. But over the weekend I got together with a new band and realized I need a small, reliable, pedal platform amp and I don't currently have anything that fits the bill. So I decided my Monoprice is going to become the donor amp for a new build.

It's an okay amp, amazing for the price, but as an occasional builder, you can't get a cabinet+chassis+speaker+tubes+transformers for $200 anywhere, so it's a no-brainer if you have a plan for a 15W build.
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I'm building a 59 Bassman, just the speakers at WHOLESALE price cost me $89 x 4 + tax and shipping. That was last years price, it's gone up to $99 each for the p10r-f.....
 
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RetiredUnit1 said:
I'm building a 59 Bassman, just the speakers at WHOLESALE price cost me $89 x 4 + tax and shipping. That was last years price, it's gone up to $99 each for the p10r-f.....

And I decided to buy a eBay 'rawcabs' cab instead of building it just 'cuz I want it done soon, so add another $314.46 for that and another $77 for pre-stain, stain and varathane..... and that's just the CABINET......
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Exactly, if I was to do a scratch build of a Marshall-esque 15W 1x12 combo, I could easily see it costing $800 or more.
 
The knobs are fugly, but that's easily corrected. On the plus side, those JJ 6L6GCs won't need to be replaced any time soon. If it has Chinese 12AX7 / 12AT7 inside, then those will get replaced. The power transformer on the 15W is undersized and runs hot, I'm hoping the power tranny in this one is more robust.
 
I picked one of these up during the latest sale and it just arrived. First impressions: it's bigger than I expected! That could be an optical illusion caused by the lighter colored cabinet, but I'm not mad about it. I haven't owned a tube amp in many years and have been using a Boss Katana 50mkii as my main (read: only) amp, mostly because it wasn't too expensive and has a 0.5w mode. So far, the Monoprice seems to deliver the sound I prefer without much fuss: mostly clean, sparkly and bright-ish, touch of reverb. It wants to lean more mids-heavy (perhaps obviously), but it's easy enough to dial in a different tone. It's definitely not capable of the low-end that the Katana puts out, but that thing is somewhat notorious for being a bit boomy. And unlike my previous tube amps, I'm able to push this thing in 1w mode without annoying everyone in a 1 block radius.

As an enthusiastic pedal builder and mediocre guitarist, it's nice to trade the infinite possibilities of the Katana for something that does just one job pretty well. And, let's be honest, I really wanted something I could modify without having to break out a USB cable and desktop software.
 
The 1W switch is not really a power switch. It's a gain switch for the 1st two stages. You can drive the amp to full power with the 1W/15W switch in either position. I added an attenuator between the amp and speakers (also purchased from Monoprice) so I can truly dial down the speaker power while running the amp at full power. Try plugging it into a 2x12 cab and see how you like the tone.

The TONE pot is between the phase-inverter and output stage. It is very effective at mellowing-out the distortion when the VOLUME is turned up.

Most of the parts are surface mount, so mods other than tube swapping are not as easy as we might like. I replaced the 1st tube with a 12AT7. Some people say that 12AU7 is also a good option for increased headroom.

I'd keep it stock until the warranty runs out. Don't be surprised if one or more of the Chinese 12AX7Bs gets noisy after a few months.
 
Time for this thread to get a conspiracy theory bump.

So I had pulled the stock tubes out of the monoprice and stuck them in another amp while the monoprice is getting overhauled. The stock Monoprice tubes are blank, no logo, no brand name, just a small manufacturing date code on the side.

Well tonight I was cleaning up the workbench and found a pair of matched Psvane 12AX7, and figured I would swap them into the amp I had the MP tubes in. As I briefly set them next to each other on the floor, it seemed odd that the tubes were the same size, Psvane are a little shorter than most 12AX7. I picked one of each up to examine them closer, and the internals of the tube were 100% identical. Tube manufacturers all have proprietary steps in their process that make them different, so it's common for things to look a little different between two brands. These were IDENTICAL.

Growing suspicious, I threw the MP tubes into my uTracer tube tester. One of the things I've noticed about the Psvane tubes I've seen, despite their datasheet giving a mu of 100, they consistently test in the 80-85 range, a little low for a 12AX7. Well on the Monoprice tube I tested, one triode came up as 80 and the other as 82. Right in line with all the Psvanes I've tested.

Psvane are supposedly a "premium" Chinese tube*, but based on every test and check I am able to do, they seem to be completely identical to the no-name tubes found in my Monoprice amp. I don't know what this means, but it's bothering me.



Yes, I'm well-caffeinated this evening.



*YMMV I used Psvane for a few months totaling about 200 tubes installed in customer pedals, and they had a much higher failure rate (about 20% within 3 months) than I've seen in JJ tubes (less than 1% within 3 months), my usual brand
 
Chuck D. Bones said:
All of the Chinese tubes may very well come from the same production line.
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vigilante398 said:
Time for this thread to get a conspiracy theory bump.

So I had pulled the stock tubes out of the monoprice and stuck them in another amp while the monoprice is getting overhauled. The stock Monoprice tubes are blank, no logo, no brand name, just a small manufacturing date code on the side.

Well tonight I was cleaning up the workbench and found a pair of matched Psvane 12AX7, and figured I would swap them into the amp I had the MP tubes in. As I briefly set them next to each other on the floor, it seemed odd that the tubes were the same size, Psvane are a little shorter than most 12AX7. I picked one of each up to examine them closer, and the internals of the tube were 100% identical. Tube manufacturers all have proprietary steps in their process that make them different, so it's common for things to look a little different between two brands. These were IDENTICAL.

Growing suspicious, I threw the MP tubes into my uTracer tube tester. One of the things I've noticed about the Psvane tubes I've seen, despite their datasheet giving a mu of 100, they consistently test in the 80-85 range, a little low for a 12AX7. Well on the Monoprice tube I tested, one triode came up as 80 and the other as 82. Right in line with all the Psvanes I've tested.

Psvane are supposedly a "premium" Chinese tube*, but based on every test and check I am able to do, they seem to be completely identical to the no-name tubes found in my Monoprice amp. I don't know what this means, but it's bothering me.



Yes, I'm well-caffeinated this evening.



*YMMV I used Psvane for a few months totaling about 200 tubes installed in customer pedals, and they had a much higher failure rate (about 20% within 3 months) than I've seen in JJ tubes (less than 1% within 3 months), my usual brand
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Chinese tubes all started with one company, everyone got rich, then split and started a new company, and it happened again, and again. Here's one https://linlaiglobal.com/
 
RetiredUnit1 said:
Chinese tubes all started with one company, everyone got rich, then split and started a new company, and it happened again, and again. Here's one https://linlaiglobal.com/
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Yup, that's the one Psvane split off from. They were originally just hi-fi tubes, so guitarists were excited when they started making 12AX7 and such, but apparently when they did the quality control started slipping and it led to the line getting shut down a couple years ago. So these may be the exact same tubes, just manufactured without the Psvane logo because Psvane 12AX7 don't really exist anymore.
 
this seems in line with some origin stories of some of the early Monoprice products that were no-brand-name (or MP branded) copies of computer speaker systems, then home theater systems that were selling for much less than their nambe-brand counterparts. Some tear-downs on the speakers suggested they were coming from the same production sources. The products got rave reviews for quality and price. Over time MP has built out some products that stand on their own merits but it is likely the parts in those products still have origin stories to other established manufacturing sources.
 
vigilante398 said:
Yup, that's the one Psvane split off from. They were originally just hi-fi tubes, so guitarists were excited when they started making 12AX7 and such, but apparently when they did the quality control started slipping and it led to the line getting shut down a couple years ago. So these may be the exact same tubes, just manufactured without the Psvane logo because Psvane 12AX7 don't really exist anymore.
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You know I had them bookmarked on my home page, and I started to open it anymore and it was a dead link. Didn't really think much of it at the time....
 
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