$149 Monoprice Tube Hybrid Amp

It's simple. Click the image icon when posting, and then paste the URL of the image itself (not the image's page).

Or you can use the following coding before and after the image URL:

[url ]https://lh3.googleusercontent.com/v...0fB4i6iiuDM22QRI6Qw7ARWlauQ=w5760-h3600-rw-no[ /url] (but remove the blank spaces that I added).

 

Much obliged

 

According to some reading (and the data sheet) the Fairchild TIP42C has something more like a 60 watt output. I'm guessing it depends on how it's used in the circuit, though. Sure would make sense, considering how well it drives my speakers.

 

Once apart, a front view of what there is to deal with in removing the tube "protectors"

Propping it up under the xformer box helped a bit.

I calculated that it would require approximately a 15mm fastener. Fortunately, a local hardware chain here in Washington State has a one of the largest fastener departments in the area. The box stores pale in comparison. I found some 3 x .50 x 16mm black allen head screws that fit the bill. Even matched the top xformer cover screws! Same thread pitch so you can retain the original nuts.

That pesky glue they use on the threads. probably the worst part of the job. You might want to have a little grow out on your thumbnail before attempting. Note the isolation washers, remember to retain these upon reassembly.

After some trial and error, I came to the conclusion that doing each protector one at a time made the most sense. To keep the black plastic spacer in place, I followed through and pushed out the stud with the allen screw. Remember not to over-tighten upon reassembly and damage the PCB.

 

After, calculations about right.

Ready to hookup and give it a test drive. Sure do like the looks of those unobscured Svetlana =C= logos!

 

Nice Labor Day listening sesh...

 

You're not uploading your images correctly. They don't appear on the page.

jeff

 

Pretty cool. I don't mind the tube protectors - I like the 'space age of the 70's look. Your mod looks clean - but an alternative would be to just remove the tubes -and trim the threaded bar and just re-install the cap nuts.

 

Pictures look just fine. Did you notice any sound improvement with the Russian tubes?

 

Thank you! That had crossed my mind in the planning stages. Cutting studs and chasing threads sounded like too much work to me, and I am a bit lazy. Haha. Also, I'm more of a murdered out/less chrome kind of guy. It cost me 7.00 in fasteners

 

Thanks! I'd like to think so, it's been so long now. I'm considering putting some Chinese 6N1-t's that I have acquired (T being military grade) and original 6P1's to see if I can hear a marked difference. There are a few I've read about out there that actually prefer the Chinese tubes for there brightness.

 

Maybe Firewall issues? I'm obviously new to the forum get-a-round, judging by my previous exchange with
action pact

 

Your way is definitely the best and cleanest method - looks completely factory.

 

That's a distinct possibility. Where are you uploading your images from?

jeff

 

Thanks again, costerdock! BTW, I have an overabundance of NOS russian tubes (and chinese t's) I'd be willing to part with, if you'd like to try some out. Not looking to profit. PM me if interested

 

I spent a good part of the morning yesterday researching how to get pictures from my phone to a URL. Finally decided on Google+, since unbeknownst to me, I already had an account through Google.
*edit* And I don't do Facebook anymore

 

I also forgot to mention, the PCB is held in place by those studs. If you cut them prior to disassembly, they might fall inside the unit. Fair warning, could turn into a real PITA.

 

What would be a good pair of speakers to match with one of these units?

 

I have a pair of Technics SB-CR77s. Would this amp work for them?

 

Those are 90dB efficiency as rated and 8 ohms. It would depend greatly on what kind of listening. Closer-in, you should have enough volume overall. I would think your 15" Technics would be a bit starved on some challenging dynamics, thick bass on pop songs and so on, but you do have a solid 15WRMS per channel and maybe 25-30WPC on typical music peaks. It isn't too hard to find speakers with 93-96dB efficiency and this amp should play them at least ~3-6dB louder than the SB-CR77s, an easy gain. Much higher efficiency speakers tend to be much larger and heavier and more spendy. And 4-ohm speakers would be a good choice to get the full output of this SS amp.

 

Thanks Bob!

 

I'm going to pick up a refurbished unit. For $100 it's worth a try. I'm planning to try it with a pair of Paradigms that are hooked up for watching movies with the kids. Nothing fancy, just a two channel setup currently being driven by a cheapo digital amp. If it doesn't workout I'm sure I'll find another use for it. I think the kids would get a kick out of the meter as well as the tubes glowing while we watch a movie.

 

Is it the case that, for the 4-ohm speakers (like the Audioengine P4B), efficiency is not an issue relevant to amps like this one (with lower output)? I'm interesting in getting one of these to drive a small office setup, but I will need to get speakers to match.

 

Those look like an excellent choice. I've used 6 ohm 2-ways, 85 dB sensitivity and they were great in a small room.

If you're using a small amp though I would try for the most efficient speakers that you can find if they meet sound quality, size, design you want. If you push this little MP amp it WILL clip, so efficiency can mean a less restrained and less harsh sound.

 

Update: Replaced the smaller tubes (6N1s) and they introduced some type of EMF via h/p, which I was unable to rectify, therefore, I replaced it with the OEM tubes, no EMF, go figure...I kept the inner two tubes in their sockets as they sounded a bit warmer than the OEM 6P15s. Hope this helps someone as I struggled to determine the cause of the EMF with the new 6N1 replacement tubes.

Peace and blessings,

Azekecse