MonoPrice 15 Watt Tube Amp

Started by philjynx, June 23, 2017, 12:47:38 PM

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philjynx

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Elantric

#1
Quote from:  philjynx on June 23, 2017, 12:47:38 PM
Well its not all bad news. If Boss hadn't made those claims, this thread wouldn't be here, then I might not have heard of the Laney Cub12 which now has a place in my redifined future!

the MonoPrice 15 watt is built in the same factory - often goes on sale for $159
https://www.monoprice.com/product?p_id=611815

http://www.tdpri.com/threads/monoprice-15-watt-tube-amp.609524/
QuoteThe word on the street is this is a Laney cub 12r in a different cab and with a spring reverb instead of digital like the Laney. I've seen gut shot pics of the Laney and it sure looks the same as the inside of my Monoprice 15 watter.

https://www.gretsch-talk.com/threads/monoprice-15-watt-tube-amplifier.154315/





Price drop at Monoprice for Guitar gear

https://www.monoprice.com/category?pg_no=3&c_id=115&cp_id=11501&searchtype=MultiCategoryId&fq=MultiMainCategoryId:115&fq=MultiCategoryId:11501&fq=is_parent:True&fq=is_parent:True


nice 15 watt Tube Amp $179
Same as a Laney Cub 12r - just different reverb tank

Opinions:
http://www.tdpri.com/threads/monoprice-15-watt-tube-amp.609524/

IMPORTANT READS
http://www.epiphonetalk.com/threads/nad-monoprice-proaudio-611815.1562/
http://www.epiphonetalk.com/threads/nad-monoprice-proaudio-611815.1562/page-2







15-Watt, 1x12 Guitar Combo Tube Amplifier with Celestion Speaker & Spring Reverb
Get superior guitar tone and flexibility using this 15-Watt, 1x12 Guitar Combo Tube Amplifier with Celestion Speaker & Spring Reverb from Monoprice!

As the title indicates, this guitar amplifier features a 15-watt tube power amplifier and a Celestion brand speaker. It uses three ECC83/12AX7 preamplification tubes and two EL84 power tubes for the amplifier section, plus a Celestion Red Truvox 1215 speaker. The EL84 tube is the tube that powered the Mullard amplifiers favored by the British Invasion bands of the 1960s. It can produce a full output from a relatively small signal and is therefore easily overdriven to produce that distinctive chiming, treble-heavy sound, especially when compared to the 6L6 tubes more commonly used in 1960s era American guitar amps.

The amplifier handles frequencies between 80Hz and 10kHz, with hum and noise -75dB below the rated power and 0.5% total harmonic distortion. It includes a Low input and a High input, with the former attenuating the signal by approximately 50% and the latter being easier to overdrive. The cabinet is ported in the rear and features a leather handle, cloth speaker grill, and a cream-colored, textured, synthetic leather exterior with chrome corner guards.

The amp features a genuine spring reverb with the ability to enable it remotely using a foot switch. It supports FX send and receive, so you can either connect it to an effects processor or use the send/receive connections as line out and line in connections. Two inputs allow you to select between the full power mode and a 1 watt limited amplification mode for recording or late night practice sessions.








Shingles

Surly it's worth a few extra bucks to have a Laney badge? Maybe only a Brit Laney owner would think that. 😜

Hmmmm.
Looking at that schematic, it's a nice design. But the power amp is fixed bias and has negative feedback, so I doubt it can do what a Vox can do.
Nik
--------------------------------
Tonelab, VG99, Axon AX100, EDP, Repeater
Godin, PRS, Crafter and Roland guitars
Center Point Stereo Spacestation V3

GeePeeAxe

I never saw the Monoprice version in Europe. Initally I have planned to buy the Cub head by Laney, but the combo, which I found in Bratislava, Slovakia, was only 20 euro more than the head. Meanwhile I really love the built in Laney HH speaker. To my ears it sounds better than the V30 Vintage by Celestion, which I use now only with a Bugera head.
BTW: the Laney cub 12 takes pedals very well, sounds really like 60es or 70es rock recordings.

TuningMachine

Quote from: Shingles on June 24, 2017, 01:47:12 AM
Surly it's worth a few extra bucks to have a Laney badge? Maybe only a Brit Laney owner would think that. 😜

Hmmmm.
Looking at that schematic, it's a nice design. But the power amp is fixed bias and has negative feedback, so I doubt it can do what a Vox can do.

Most amps built since the 60s have the neg feedback loop.

Shingles

Quote from: TuningMachine on June 24, 2017, 06:18:31 AM
Most amps built since the 60s have the neg feedback loop.

Yes, but not Vox AC30 and AC15, the two amps that most EL84 amps are trying to emulate. That's why Vox amps sound that way, that and the cathode bias. So to build an EL84 based amp, with a British name badge, and give it negative feedback and fixed bias operation, makes no sense to me.
Nik
--------------------------------
Tonelab, VG99, Axon AX100, EDP, Repeater
Godin, PRS, Crafter and Roland guitars
Center Point Stereo Spacestation V3

Shingles

Quote from:  philjynx on June 24, 2017, 07:56:49 AM
Possibly stupid question coming up...
I don't know enough about electronics, this is a pretty reliable fact of life.

So, could the pots on the Monoprice (Laney Cub 12 in my case as I'm in the UK) be replaced with digital pots in order to build pre-set and midi control over this little gem?

Yes, but it would cost a lot of money and effort to do it. That's how the Mesa Triaxis preamp works; also the Marshall JMP1 preamp and various others. Valve amp circuits with the pots replaced with digitally controlled attenuators so that they can be made programmable.

Alternatively, I understand Neil Young uses a gizmo that actually turns the pots on his vintage fender amp(s) to achieve programmability. Don't think it was ever a commercial product, 'though.
Nik
--------------------------------
Tonelab, VG99, Axon AX100, EDP, Repeater
Godin, PRS, Crafter and Roland guitars
Center Point Stereo Spacestation V3

Elantric

#7
Quote from:  philjynx on June 24, 2017, 07:56:49 AM
Possibly stupid question coming up...
I don't know enough about electronics, this is a pretty reliable fact of life.

So, could the pots on the Monoprice (Laney Cub 12 in my case as I'm in the UK) be replaced with digital pots in order to build pre-set and midi control over this little gem?

Arduino - : Adding MIDI Control to a Guitar Effects Pedal
http://forum.arduino.cc/index.php?topic=480635.0

https://www.vguitarforums.com/smf/index.php?topic=21090.0

vtgearhead

Quote from: Elantric on June 24, 2017, 08:47:19 AM
Arduino - : Adding MIDI Control to a Guitar Effects Pedal
http://forum.arduino.cc/index.php?topic=480635.0

https://www.vguitarforums.com/smf/index.php?topic=21090.0

I think stepper motors bolted to the pot shafts would be way cooler :-).  If I parted out all my defective 5-1/4" floppy drives I'd have enough to handle almost any tube amp. 

Elantric

#9
Quote from: snhirsch on June 24, 2017, 09:23:31 AM
I think stepper motors bolted to the pot shafts would be way cooler :-).  If I parted out all my defective 5-1/4" floppy drives I'd have enough to handle almost any tube amp.

Similar to the capstan motors in old tape decks , You'll have to wrap the stepper motors with MU metal EMI:RF shielding to prevent  the radiated EMI   From the stepper motors and stepper motor drive amplifiers invading into the sensitive tube preamp.

Else you will experience 100 dB of  stepper motor noise whining  with each patch change


But if you must proceed with caution and here are the details

http://hackaday.com/2015/10/09/controlling-guitar-amps-with-servos/

http://trigonometrie.bplaced.net/blog/terrorbot






Elantric

#10
Quote from:  philjynx on June 26, 2017, 10:52:03 AM
Any idea anyone regarding the likelihood that digital pots would survive in place of the mechanical ones in this valve amp?
:)

its all about the voltage swing on the specific pot


The Caps in Yellow block the high + 250VDC Plate voltage from the tone stack pots 


most digipot ICs restrict this to less than +/- 15V swing,

Best to get an oscilloscope and probe the pots and take notes before contemplating a digipot IC based automation solution


Elantric

#11
Quote from:  philjynx on June 26, 2017, 10:57:56 AM
Will a digital multimeter do or do they not react fast enough for this particular task?

depends on the multimeter  - measure both DC voltage and AC Voltage

the restriction is many multimeters can not measure AC voltage above 400Hz

This is a good value - can measure AC Voltage up to 1kHz

UNI-T UT61E $60


https://www.amazon.com/gp/product/B007THZMWI/ref=oh_aui_search_detailpage?ie=UTF8&psc=1




http://www.batronix.com/downloads/UNI-T/UT61_Manual.pdf




admin

#12
https://www.tdpri.com/threads/monoprice-15-watt-tube-amp.609524/page-14
Oh, and in case anyone's curious: earlier in the thread some folks said that the similarity with the 2012 era MonoPrice 15 Watt vs the Laney Cub 12r was "alleged" or "rumored". I have it apart now, and even the silkscreened PCB labels match exactly. It's the exact same amp. Which is convenient, because the Cub schematic is easy to come by.

The "tone" control does appear to be identical to the Vox cut control, as someone else already said.


Search on "Laney Cub 12r Mods"  to improve the original version MonoPrice 15 watt amp



http://talk.philmusic.com/index.php?topic=155989.1000
https://www.google.com/search?q=laney+cub+12r+mods&sxsrf=ACYBGNTLvHxtbyWoJEyGfYqZoOGVRmLKqw:1575144457609&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjejfau3pLmAhVFO30KHQfNDAwQ_AUoA3oECAwQBQ&biw=1536&bih=762c

http://www.epiphonetalk.com/media/schema.642/full?d=1469026285

dazco

Is the schematic the actual monoprice amp of the laney? Because the monoprice has a seperate tone control besides the stack controls and i don't see it in that schematic.

admin

#14
Quote from: dazco on September 14, 2022, 04:34:36 PMIs the schematic the actual monoprice amp of the laney? Because the monoprice has a seperate tone control besides the stack controls and i don't see it in that schematic.
There have been two versions of 15W MonoPrice Amp I know of.

The schematics are for the early version with top facing controls ( like a Fender  Blues Devile )

Replace the horrid reverb tank is common upgrade



Above Amp is different than current Front Facing Control version here

https://www.monoprice.com/product?p_id=611815

SY.Borg.300

#15
The laney version has digital reverb so if the schematic shows a spring tank then it can't be the laney schematic. Other than that they're the same amp.

dazco

Quote from: admin on September 14, 2022, 04:51:40 PMThere have been two versions of 15W MonoPrice Amp I know of.

The schematics are for the early version with top facing controls ( like a Fender  Blues Devile )

Replace the horrid reverb tank is common upgrade



Above Amp is different than current Front Facing Control version here

https://www.monoprice.com/product?p_id=611815

So i guess no one has the newer schematic.

admin

Quote from: dazco on September 14, 2022, 05:21:56 PMSo i guess no one has the newer schematic.
correct

But there is not much to these amps -relativeley easy to reverse engineer and create a schematic ( given time and a need to know)

I do not have the latest version

SY.Borg.300

There is no need for a new schem. The only difference was the reverb tank which got upgraded when the chassis orientation was changed. And maybe the 1 watt switch was added instead of a low input jack.

dazco

Quote from: SY.Borg.300 on September 15, 2022, 03:34:40 AMThere is no need for a new schem. The only difference was the reverb tank which got upgraded when the chassis orientation was changed. And maybe the 1 watt switch was added instead of a low input jack.
Well, as i said i do not see the tone pot in the schematic posted here so thats one difference. Seems the old one only has treble mid and bass while the new one has those plus a "tone" control that i imagine is more than likely a overall dark/bright control that i wanted to see how it was implemented. But it's not on the schematic which is for the old model. In any case no matter, as i was redesigning a old V6 build i had in storage and just thought that might be a useful addition, but i figured out a better way to get the tone where i want it w/o that.

SY.Borg.300

#20
This old version with top mounted controls has the tone control you say is missing.

Link to pics of laney cub12r

https://www.acclaim-music.com/laney-cub-12r-guitar-15-watts-1x12-combo-amplifier-cub-12-r.html

Elantric

#21
Just mentioning,  there are two different versions of this amplifier



Early 1st version 2009-2016 have top mounted controls.  Around 2017 Monoprice introduced the new version Mono Price Stage Right 15W Tube Amp (611815)  with all controls mounted on the front on a chrome panel with a Power wattage push button switch near the power switch .



  https://www.monoprice.com/product?p_id=611815

I own both old and new versions and consider the 1st version a lifeless dog, while the latest version with front mounted controls  is a very different circuit. New version sings and sustains better than my genuine 65 Fender Deluxe Reverb - can not locate schematic to latest 611815 version which apparently is also sold as the latest Harley Benton Tube15 Celestion Amp. https://harleybenton.com/product/tube15-celestion/

I have been able to locate an amateur Bias adjust youtube video revealing the internal SMD Component PCB, unit appears to be much lower assembly cost vs original version , but side by side comparison reveals  there is a substantial sonic difference - much prefer the latest model - purchased on sale at lower cost than retubing my Vibrolux Reverb

( mute the sound, just used as reference for internal view of latest model )




Other review that matches my experience

https://www.gretsch-talk.com/threads/monoprice-15-watt-tube-amplifier.154315/page-4#post-1017167

QuoteTommer Jay

Detroit
Jan 15, 2018

I had been searching for a small amp to replace my 50lb, 50w 112 Combo I have been lugging around to gigs for the last 6 years. Like every sound man, our sound guy despises stage volume and had me running my volume so low it just didn't make sense to bring that amp out anymore. I have an Epiphone Valve junior I brought to a couple gigs but it was a little tight on headroom for the pedals I put through it. I stumbled on the Monoprice 15w and because of the good reviews I watched for awhile. I became even more interested when I heard this could possibly be a rebranded Laney Cub 12R. (I was going to pull the trigger on the Laney until I found this out)

I got lucky and purchased this amp about 2 weeks ago for $159.00 on the Monoprice website. It was the lowest price I had ever seen for it so I made a snap decision to purchase. (It may have been refurbished as it had a few scuffs on it) How could I lose? If all went south, I would still have a decent celestion speaker in a cab I could use.

LET ME TELL YOU SOMETHING......I am totally impressed by this thing. I used it at the last 2 gigs and it is the best sounding amp that I have ever used for small club gigs.
I use in-ear monitors and some of the other amps I used had harsh over tones and tinny sound through them. This thing sounds smooth without the harshness and extreme high end sizzle.
Headroom is great for pedals if your not looking for that extreme over driven tube break up. This thing at 15watts is loud too. I use it in one watt mode at the gigs(mic'd up) and it is perfect. It actually seems as loud as the Valve Junior at 1 watt.

While you normally get what you pay for, I guess I'll see if this thing will last the approx 45 gigs we do a year. I was actually thinking of buying a second one for backup.

In my opinion, For the $199.00 price on the website this thing is a steal. Thumbs up from me to anyone thinking of purchasing.

Elantric


Dugbert5

I am an amateur who would like to mod an SR15 to sound more Fendery. Does anyone have any suggestions?

SY.Borg.300

Put an eminence speaker like a GB128 in it. That's about all the mods I would recommend unless you are good at soldering surface mounted micro parts like on cellphones ect. Your main obstacle to sounding like a fender is the el84 tubes in the SR15. That's not the classic fender sound. If you can get a good tech you can think about having him disconnect the tone stack.