$149 Monoprice Tube Hybrid Amp

Nice, that's what I'm waiting to hear, more evaluations. What tubes did you replace the Chinese tubes ?

 

2 x 6P1p Svetlanas dated 1968 and 2 x 6N1P 1967 Voshkods

At first I felt they sounded really sterile, like my first CD player from way back when - like almost metallic. Can't think how else to describe them. After 15 hours of burn in things started to sound more natural and about 25 hours in they sound superb. I can't leave tubes on for hours as we have a four year old that would probably try and touch them when the tubes are hot so it's always off at the mains, so it's taken me a while to get the 25 hours of burn in - that said less time at the doctors treating burnt little fingers means more time for listening

I had read elsewhere that others like the Chinese tube sound on this amp, its possible that mine had old used tubes or tubes from a bad run. I switched back a few weeks ago for one album to see if it was all in my mind but they were muffled as previously described.

 

they really need a native english speaker to help with their presentation pictures

 

Seriously. At 90hz it can't even reproduce the fundamental of a guitar's low E (82hz), never mind that of a bass (41hz)

 

Anyone who has this try the headphone out, or compare it with another headphone amp?

 

I often use the headphone jack from my Grado SR80e's and it sounds good to my ears. There is no hum etc. Perfectly acceptable.

At this price point you won't be disappointed.

 

I was all set to take the plunge using a $20 off $100 promo code 1STDOWN
Get all the way to checkout, and where the heck do you enter the code?
They've re-vamped the site and the promo code option is nowhere to be found.
Very frustrating! I guess I won't be able to give my review on this little amp after all.

 

"Go to View Cart, not Check Out, and make sure you're not logged in. Clear the cart and start over if it's giving you a problem with that.

It's the same item in my cart above, so I don't think that's it. It would let you apply a promo code even if it doesn't t work for anything in the cart."

Quoted from another forum where someone else was having a problem entering promo code. It doesn't look too difficult...

 

Yep, tried that. Tried different browsers. Tried different items. Tried different days. The promo code box is just not there. Maybe I will call them.

 

Just ordered one of these from Amazon, should be here on Wednesday.
We'll see how it goes, should be fun to play with.
Now on to hunt for some replacement tubes...

 

FYI customer Service Chat results: "The section to enter the coupon code at check out is removed from our site when there are no active codes to enter. The promotion that we recently had for the 15% off, was a one day offer only, that was only valid for orders placed yesterday."

Guess I missed my chance...

 

More than one guy said the tubes were there for show. Here is one review.

This amp is a scam - pure and simple. Being an EE and audio enthusiast I took this amp apart and discovered that the tubes do not connect to anything. The "transformer cage" contains no transformers. The amp uses cheap Fairchild transistor class AB amplifier, the tubes have only heaters connected to unregulated transformer secondary. Nobsound guys a frauds.

My brother in-law-was looking at my CAT Tube amps and asked me if the tubes were just there for show.

 

Wow.

 

The amp is not a tube amp only the preamp section so that reviewer sounds misinformed.
I don't own one of these but i'm curios about this company and others. Some interesting products for sure. Looking forward to more hands on reviews.

 

You could be right this is the internet after all.

 

Monoprice has a pretty good reputation and I doubt they would sell something that's a total scam...but you never know until you dig deeper. Interesting product either way...

 

The reviewer is mistaken, I have changed the tubes and have a different sound signature - see my earlier post.

 

It seems to be a mixed bag with the reviews, some quality issues which I would expect, but nothing proving this is outright fraud.
Mine is coming from Amazon today and with the weather coming in on the East coast, I should have some time this weekend to do some testing.
If nothing else, it will be fun to play around with and if it doesn't work, I'll send it back.

 

Please share your impressions once received! I'm on the fence about buying one.

 

I picked up the Nobsound MS 10d MkII a few weeks ago for a good deal on CL barely used. I believe them to be very similar to the Monoprice outside of how the Bluetooth is implemented. Also, the NS (i hate saying that name) has a rudimentary USB input/interface. The Bluetooth isn't working on mine, but wasn't a big deal for me because of the great deal that was had. I've received some tubes from "that" auction site for rolling. Svetlana 6P1P EV's dating from '81 and some Novobirisk 6N1P EV's dating from'71. Haven't had enough hours on them for finite details but they definitely made a difference right off the bat. Also, they are in the signal path. When you turn the amp on from cold, there is no sound until the tubes warm up. I am running it with a pair of Miller & Kreisel B1600's. It's a very nice match up, IMO.

 

ephilbe is correct about the tubes. The unit will not produce sound until the tubes warm up and start conducting.

The Monoprice web site even says: "The tube preamp stage adds warmth and richness that solid-state circuits can't touch......"

I took the bottom off of mine and snapped a couple pictures.

Here's the inside:



Here's a close up of the circuit board where the tube sockets are mounted. You can see there are traces to all the tube pins.



Under the "Transformer Gage" is the power toroidal transformer..... tough to see through the hole in the pic. The bolt head you can see is holding the toroidal transformer. There are no output transformers being a solid state power amp.



I guess the easiest way to tell if the tubes are in the signal path is to remove them and see if the unit works!

It is a nice little amp for the price.

 

Thanks for the pics xmas111, it looks about like I expected.
I got mine last night but haven't opened it yet, I'll have to wait until Saturday for that.

 

Yes, thank you for the pics, xmas111! Out of curiosity, did you happen to take note of what opamp they are using? I wonder why they use 2? I've considered installing a receptacle and rolling chips as well.

 

unfortunately I didn't notice what the op amps were....sorry about that.

 

No worries whatsoever! Definitely cool to have a peek inside and debunk the myth once and for all.

*edit* Pulled the photo up on my big screen and believe I can make out 4558. That would certainly jive. Still wonder why 2, though. 4558's are two channel opamps.