Boomy, I just got to tell you that the picture of that DIY with a handle reminds me of something that the Navy made me carry around in the early 1980's. Bet yours sounds better though... mine just beeped and booped.
I got a 20.00 alluminum breifcase tool case from HomeDepot and just started adding Stuff. It has a 4 Pin Mini xlr balanced between the two amps and a nothe Mini xlr with 160 ohms of resitance for my IEMs. The two Mono 6.3's are 0 ohms. The wood is just pieces of oak left over from when I made some kitchen cabinets. The usb Dac/Midi is an Alesis io2 mini studio. running balanced into the dual mono Indeed amps. Not true balanced as the grounds are common at the power source.
Originally Posted by boomy3555 /img/forum/go_quote.gif The EF2 is a higher quality Tube/SS hybrid so you get the flavour of the tubes but then some power from the soldid state section. The EF2 also uses two 6 pin tubes (Ihave Mullards in thier now) and are easier to find thatn the Indeed 6922/7308's.
It's pretty hard to argue that the 6AK5 and its equivalents are easier to find than the 6922/6DJ8 and its equivalents. Cheaper, for sure, but not easier to find.
I should clarify that I have found plenty or cheap 6922's but not many higher end Mullards or Telle's in that group. The only reason I got some nice Jan Sylvania 7308's was I traded a tube tester for some. but Skylab is the tube guy so I must default to his judgement.
One nice Mullard equivalent to the 6922 is the CV2492. But they can be expensive. And there are also lots of Amperex variants. Telefunken certainly had lots as well - ECC88 and E88CC, and some other variants.
I finally got mine today, and right out of the box it sounded bloated on the bottom end, muddy and thin in the middle and a little harsh in the highs. A couple hours later, it still doesn't sound right for electronic, but I listened to some Yo Yo Ma, and holy kerfuffel it sounded good. For the first time (not like I have listened to a lot), something I tried made a significant, audible, and enjoyable change. I got the soundstage I have been looking for. On my E2C's! A noticeable spaciousness that was just perfect for a Yo Yo Ma solo. I can't wait to see how this changes after a couple more days of burn in. I may not even use the Jan Sylvania I got from Boomy if I am satisfied with the stock tube. I could use the extra scratch to buy more cable supplies.
To think, I was on the verge of putting this up for sale before I had received it. That one Yo Yo Ma solo has convinced me that I have to keep it now. I can't wait to try it with my SRH840's when I get home.
Cheers,
Give the stock tube a good burning in and then change to the JAN Sylvania just for the heck of it. The JAN Sylvania 7308's are still what I have in the Indeeds I have around.
I'm not looking to ignite anything, but what exactly is "burning-in" with this amp? Is the stock Chinese tube extremely new and needs to settle?
One other question for the owners of this amp that also have experience with full fledged tube amps:
How does this amp compare to all the rest in terms of diminishing returns? For example, would this thing be comparable to the Grado SR60 in terms of raw performance for the price? Does this little guy deliver 80% of a thousand dollar tube amp?
Yes, the tube is new and needs to settle in. I don't think that tubes needing burn in is even debated much anymore. If you want a great debate (holy war) go check out threads discussing whether super duper cables make a difference.
Not having heard anything better than what is in my signature, I am still floored by how this little (tiny) guy has allowed me to enjoy my music, particularly my classical and jazz. I don't think any $50 amp will give you 80% of a $1000 amp (you weren't serious were you), but it certainly is an outstanding value to the point that unless I upgraded to headphones that simply couldn't be powered by this amp, I would feel no need to get anything better. But I am strictly budget fi.
Although this little guy can never compete with the big boys, It's a great little starter amp fo new "Tubies". There is such a big difference between solid state and tubes that I and others were shocked by the quality and richness of the SQ. partialy because it was our first tube amp period. ( I started buying these and the EF1 at the same time so I had a slightly better amp in the EF2 to a and b with)
I suppose many headphone users here buy this small and compact headphone amplifier is because it is well priced(cheap for what it can do) and also users can tube roll the 6N1 tube with 6DJ8 or 6922.
I thought what I can do is to replace the input tube with a solid state ie FET(costs less than 50 cents each) so that
1. there no need to tube roll and
2. listen whether there are any differences between tube and FET sound.
I bought 2 units and pull one apart and the the other remains unchanged. I modified one unit in incorporate a low noise input FET and output MOSFET remains the same. I was able to compare the 2 units. What are the differences you want to ask?
There are more similarities than differences.
Similarities
----------
a. The sound stage remains unchanged, both can generate a large soundstage.
b. Both are able to drive low load headphones and they are Class A amp.
c. Only subtle differences in both units, see below
d. Distortion(THD) of both units are at similar level lying between
0.2 to 0.5% @ 1V rms output.
BTW most Cmoy amp cannot drive low load headphones and cannot generate large sound stage
Differences
-----------
a. FET sounds a little cleaner and more distinct in the sound reproduction whereas the tube sounds a little "tubey" and smoother.
b. FET sounds a little more dynamic than the tube.
According to my ears there are very little differences between the 2 units, I believe the reasons being both have similar distortion levels and both units belong to a same configuration/circuit topology.
If those who can perform changes to this amp, I like to suggest besides changing components is put a large heatsink to the MOSFETs and current regulator. The current heatsinks are "too small" this my next project.
Anyone else received their little bundle of joy yet? Mine left HK yesterday, so I have a couple of weeks to go. Roll some tubes y'all!
My first tube will either be Phillips JAN 6922 or a German RCA 6922 (silver shield Siemens). Both NOS. I also have an orange label Amperex and a Philips Miniwatt en-route.
Question for people more knowledgeable than me: I get some significant hiss when using the this little fellah with my 16ohm IEM's. Does anyone have any idea how strong a resistor I should use to reduce the hiss? It isn't horrible, especially once the music starts, but I have the DIY bug and want to make a resistance adapter.
I often end up using a resistor so I can up the source input. This helps with the low volume hiss. I use a Ultimate Ears 50 ohm inline resistor but when I made up my breifcase toolbox I put 160 ohms of resistance to one of my 4 pin mini-XLR jacks. I have only used cheap Ratshack resitors, but I hear that "Mills" resistors are excelent for making DIY attenuators.
Ok! Got my Bravo today! WOW! I am extremely happy with this little amp. I've been running FLAC files from my laptop to a bass guitar headphone amplifier by utilizing the aux input.
First thing I noticed upon firing up the Bravo was that the soundstage opened up significantly. Sounds now come from many different areas in 3D space, and everything is more coherent and "together". Next was the detail. Being a bassist the first thing I noticed was that I could easily hear the tone of the bass being used. Everything has texture! I had no idea this amp would make such a big difference.
Also, I have not heard the sound of the stock chinese tube. I had a JAN Sylvania 6DJ8 waiting and I popped that in as soon as the Bravo was unpacked.
Funny. I am *sure* that much more expensive amps will not provide another huge leap in sound quality like I have just experienced. I am very content knowing that I can have outstanding quality from this extremely affordable amp.
Oh, I am running Senn HD600's. Also, for what it's worth, the heat sinks on this guy became so hot so fast I found it comical. Ahhhh, class A!
This amp is highly recommended. You can always do better for more dough, but the Bravo is so much more than adequate.
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