Monoprice 25 tube hybrid

Kornbread

   Anyone have experience with them?  Some of the real reviews are not that exciting.  They are on sale for $99 so ordered one for boy's dorm room.  It should drive the PicoNeos and his headphones ok.  Just not sure of the sound. 

  

   Also ordered him one of those cmoy headamps in an Altoids mint tin, plus all necessary cabling, for something on the go.  

dcibel

I had one when they first came out. The noise floor was awful, unusable for my needs. Maybe they've modified the design since, but what I had wasn't a hifi product. Looked nice on the shelf though.

Kornbread

That sucks.  Hopefully I can return it if that happens.  

PWRRYD

I bought one too.  Nice looking case which I plan to repurpose at some point, but one channel didn't even work!

Kornbread

Craig, I had considered asking if you might want to build one or walk me along in building one. 

Tom_S

You could make a simple low power SE amp out of it. You might get 2 watts at 5% distortion. The 6p15 is very similar to the EL84. Decware has been using a single 6n1p (Russian version of the 6n1) to drive an EL84 for years. 

Kornbread

You tube heads know I'm looking for a very affordable tube preamp ... right ...

Tom_S

There are a ton of pretty simple linestage designs out there that actually sound good and don't cost a fortune. This would be good start - http://diyaudioprojects.com/Tubes/Universal-Tube-Preamplifier/

Kornbread

@Tom_S ; Couldn't find a parts list for the 4sUniversal preamp you linked.  Disregarding some high dollar branded tubes, I assume the transformer will be the most cost?  Any idea what everything might cost, excluding the case? 

If I had some help ... maybe a lot of help ... I'd like to try building that one.      

PWRRYD

Tom, your 12BH7 SRPP preamp was pretty straight forward and affordable.

Tom_S

Kornbread said:

@Tom_S ; Couldn't find a parts list for the 4sUniversal preamp you linked.  Disregarding some high dollar branded tubes, I assume the transformer will be the most cost?  Any idea what everything might cost, excluding the case? 

If I had some help ... maybe a lot of help ... I'd like to try building that one.      

You/we would have to make a parts list based on the schematics. Mouser & Digikey both have the power transformer for around $50 - the choke is only $13 and change. Edcor has some that would work too, but they make each one to order, so there's a 4-8 week wait. I always make my own cases. That's half the fun for me. PE has some dual 32uf/500v  caps that would work great and look cool sticking up out of the top plate. There are quite a few of us that can help you through it, but I think you'll do fine. This is maybe the simplest design I have ever come across & they have a long dedicated thread on their forum. I wish this design had been around when I bought my first Bottlehead kit years ago. That Foreplay linestage was always noisy and had way too much gain in it's first iterations. 

PWRRYD

And that's still the rub these days.  How much gain do we really need?  Probably not much if any.  And who wants added noise.... Cathode followers are great if you need unity gain and need to drive long cables...  

All that said, there is something I still like about a well executed tube line stage, even if I don't need any gain and my signal cables are only 12 inches long 

Kornbread

This is a pretty darn good bunch of guys. 

@Tom_S ; Package was in the mailbox ...and he wouldn't even let me pay for shipping.  Big Thank You to Tom. 

The rest of the parts for the 4s universal pre should be coming in from PE tomorrow.  Will need to pay a visit to the local scrap yard or metal dealer for the aluminum plate and thinking Poplar for the sides.     

 

Tom_S

No problem. I just hope those tubes aren't noisy. They all tested fine in Hickok tester, but that doesn't mean they are good enough for audio. All my DIY gear uses either the 6DJ8 or 12BH7 - and I was too lazy to pop the top on my old CJ preamp to actually listen to the 12ax7s.