[fishski13]

Quote:

 
I've got a better one for trimpot screwups. I put the wrong trimpot in the VR1 spot, and after I noticed it and got it desoldered so I could put the right one in instead, I went and put the same one right back in. I felt pretty dumb that day.

who said solder fumes make you smarter?  i know the feeling 

.

 

[amb]

Quote:

Ti... you are an evil man!  I now absolutely have to build that!

Quote:

haha X2 on that....

Sorry about the off-topic post, but if you're interested in building the α10 buffer preamp, please follow (and subscribe to) the α10 thread and JISBOS group-buy.  Momentum is gathering on that front.

 

[aloksatoor]

subscribed

 

[turgonml]

I can't seem to find the CR1, CR2: 2.2mA or 2.4mA current regulator diode on Digikey (needed for the σ22. I've found almost every single part I need from digikey and AMB and I don't really want to pay an extra 20 euro shipping to get it from Mouser.
 
Thanks in advance.

 

[jackmccabe]

Hi, what is the lowest gain you would recommend to go with a pair of k1000's.
This is because I also have a pair of grado rs1's, so I would like to be able to use both of them without one be very quiet and the other very loud.
thanks

 

[johnwmclean]

Quote:

Hi, what is the lowest gain you would recommend to go with a pair of k1000's.
This is because I also have a pair of grado rs1's, so I would like to be able to use both of them without one be very quiet and the other very loud.
thanks

Balanced or Single Ended.

 

[jackmccabe]

I will be building it balance sorry forgot to say.
Thanks 

 

[amb]

Quote:

Hi, what is the lowest gain you would recommend to go with a pair of k1000's.
This is because I also have a pair of grado rs1's, so I would like to be able to use both of them without one be very quiet and the other very loud.
thanks

It's going to be difficult to make one gain setting work well for both of those headphones because they're such extreme opposites.  K1000 is super inefficient and needs high gain to achieve good SPLs, but such an amp would have too much gain for the Grado.  A switchable input attenuator might be useful to equalize the volume (I posted about this before, search for it), but it's not a cure-all.

 

[amb]

Quote:

I can't seem to find the CR1, CR2: 2.2mA or 2.4mA current regulator diode on Digikey (needed for the σ22. I've found almost every single part I need from digikey and AMB and I don't really want to pay an extra 20 euro shipping to get it from Mouser.
 
Thanks in advance.

PM me and I could help you out.

 

[GMF2010]

Can anyone confirm that they are able to use a gain of 6 balanced (3 single ended) with Denon D7000s without producing hiss?
 
My amp is currently set to a gain of 4 balanced, but my other headphones (LCD-2) leave me needing just a few more clicks on the DACT with lower recordings. If someone who has tried balanced D7000 with a gain of 6 could comment, I would really appreciate it.
 
P.S. My DAC is a Buffalo 32 with an output of 2V RMS.
 
Thanks,
 
Greg

 

[FallenAngel]

Hiss is not just about gain - it's also about how close your PSU is to the boards and Low-Z wiring after pot.

 

[jcx]

There are some things that can be determined from the specs alone:  LCD-2  50 Ohm 91 dB/mW vs D7000 25 Ohm 108 dB/mW
 
looks like the numbers say the Dennon are ~ 20 dB/V more sensitive - thats a lot - definitely where you should consider output attenuation- "Hiss Buster" or output Xfmr
 
the Headroom impedance graph is pretty flat though so the series R of a power resistive divider shouldn't introduce much coloration
 
a 20:5:20 Ohm balanced divider's output Z would be low enough that the D7000 impedance bump would give inaudible frequency response difference compared to "0" Ohm drive
 
I would just string together 9x 5 Ohm 1/2 W or or bigger 1% metal film resistors for each chan divider - they could be inside the B22 with a switch or built into a external box ( probably not just the connector headshell though because they will be wasting a few W)
 
 
also if you're using a Ivy III with the Buffalo Dac then a Volumite will give better S/N with the Dac straight in to the B22 than any volume pot setting down to nearly 20 dB attenuation (assuming 10K attenuator - higher Ohm attenuators will be even noisier)
 
 
in fact the D7000 would probably be fine straight from the Ivy

 

[GMF2010]

Quote:

Hiss is not just about gain - it's also about how close your PSU is to the boards and Low-Z wiring after pot.

With respect to the PSU's proximity to the boards, I should be fine. The S22 (x2) are in their own par-metal case, and while I do have the B22's case stacked on top of it, there is an additional inch of separation provided by the isolation feet I have. I'm not sure if an inch is negligible or not, regardless...

 

[jcx]

Hiss is "white" noise from active devices and resistor thermal noise - in the b22 the volume attenuator resistance noise at intermediate settings will be larger than the B22 input fet noise - many sources will have higher noise than the b22
 
Hum is power line fundamental - often ground loops and xmfr leakage magnetic coupling
 
Buzz is power line frequency harmonics from cap input ps rectified current spikes - can be magnetically coupled from poor wire routing or may be "ground contamination" from poor ground wiring topology
 
 
if you don't hear any of these with the LCD-2 then you wouldn't with the D7000 and the 20 dB output attenuator
 
 
since this is the DIY forum you could diagnose these problems with a decent soundcard by looking at the noise fft (RMAA)

 

[LeMat]

Since I got very important information and help in this thread, I thought some may be curious to see how winded up my first DIY experience... a Beta22.
I could't say I haven't been advised to start with a smaller project, and I won't say it's been easy, but it finally went ok. Actually it's selecting and shopping parts in so many different web-store/boutique that I've found difficult. Designing the case has been also very time consuming. All things considered, I really loved the experience ! Now I have some fine tuning to do but it already sounds really great.
 
http://www.head-fi.org/forum/thread/85561/post-pics-of-your-builds/7710#post_7214853