[gvl2016]

I'm using it with a Yamaha MX-600/JBL L100s, while the hum is mostly a non-issue it is definitely there and detectable by swithing the speaker swtich on/off, Yamaha seems to be pretty sensitive and L100 are efficient, both of which may aggravate the effect, I have attenuator pots turned down all the way, and with volume only at 11 o'clock on the DV the sound is very loud when listening from a 2VRMS DAC.

 

[41Venom14]

Here is a good question. 
 
I just snagged the Beyerdynamic DT 1990s and I cannot really tell much difference using different tube combos compared to when I was running the HD650s. Does anyone else have this experience as well, particularly with the 1990s?
 
I may just need more time with them to really peel apart their sound signature, either way they sound ******* incredible. 

 

[ThermalAlchemy]

Question, are they fresh out of the box?, or did they have 100+ hours of some hard use? I did notice my HD650 laked BASS when I first used them. I let my three sons use them for a week with my DV. One son  used them for gaming from 12am to 7am every morning for a week. When I got them back (they really opened up with sound stage and BASS)

 

[windcar]

  Question, are they fresh out of the box?, or did they have 100+ hours of some hard use? I did notice my HD650 laked BASS when I first used them. I let my three sons use them for a week with my DV. One son  used them for gaming from 12am to 7am every morning for a week. When I got them back (they really opened up with sound stage and BASS)

If you find your Darkvoice lack bass, do these:
1. Change your power cord to something thicker. The original power cord that comes with it is a lousy thin piece of S*. This amp is using standard PC power supply power cord so this should be easy to find.
2. Change your 6SN7 to some thing like RCA 6SN7 GTB, or SYLVANIA short bottle 7N7 1960s. These are relatively inexpensive on ebay. With 7N7 tubes, you will need a converter like this:
https://www.aliexpress.com/item/1Piece-7N7-TO-6SN7-Convert-Tube-Socket-DIY-Audio-Vacuum-Tube-Adapter-Socket-Converter-Free-Shipping/32616236426.html
Those are the 2 tubes I have that have increased Bass, with the RCA having slightly more BASS.
Head towards http://www.head-fi.org/t/117677/the-reference-6sn7-thread to check out various tubes' characteristics, which I find rather accurate.

 

[41Venom14]

  Question, are they fresh out of the box?, or did they have 100+ hours of some hard use? I did notice my HD650 laked BASS when I first used them. I let my three sons use them for a week with my DV. One son  used them for gaming from 12am to 7am every morning for a week. When I got them back (they really opened up with sound stage and BASS)

 
The DT 1990s are quite new, probably around 30 to 40 hours on them at this point. You are right, it may just require some burn in time. The DT 1990 is also a 250 ohm, the DV does not have any issue running them even though its getting near that lower impedance that the DV seems to not tolerate very well (aka no bass), but the DT 1990s have great bass on the DV when compared to the Jotenheim solid state, so no issues there.
 
As for the HD650s, I've had them for 6 months of heavy use, probably at least 1 - 3 hours a day. Swapping out tubes is always so good on the HD650s. Every tube sounds different, its phenomenal. I just want to see if I can tweak my DT 1990s like I can tweak my HD650s to sound just like I want.
 
 

  If you find your Darkvoice lack bass, do these:
1. Change your power cord to something thicker. The original power cord that comes with it is a lousy thin piece of S*. This amp is using standard PC power supply power cord so this should be easy to find.
2. Change your 6SN7 to some thing like RCA 6SN7 GTB, or SYLVANIA short bottle 7N7 1960s. These are relatively inexpensive on ebay. With 7N7 tubes, you will need a converter like this:
https://www.aliexpress.com/item/1Piece-7N7-TO-6SN7-Convert-Tube-Socket-DIY-Audio-Vacuum-Tube-Adapter-Socket-Converter-Free-Shipping/32616236426.html
Those are the 2 tubes I have that have increased Bass, with the RCA having slightly more BASS.
Head towards http://www.head-fi.org/t/117677/the-reference-6sn7-thread to check out various tubes' characteristics, which I find rather accurate.

 
I have changed my power cord and have quite a collection of 6SN7s, 6AS7Gs and 6080s.
 
With the HD650s, I found the Sylvania VT-231 + Sylvania 6080 to have the most delicious bass. Warm and dripping, with slight extension.
 
That same combo does not have that effect on the DT 1990s, I swapped a couple different tube combos and I personally cannot really tell the difference.
 
I think with more hours under my belt on how it sounds will help me decipher the differences. I should probably run them strictly from my Jotenheim until I really learn the SS sound, this is an idea I didn't have until just now so bear with me lol. 

 

[gvl2016]

  Here is a good question. 
 
I just snagged the Beyerdynamic DT 1990s and I cannot really tell much difference using different tube combos compared to when I was running the HD650s. Does anyone else have this experience as well, particularly with the 1990s?
 
I may just need more time with them to really peel apart their sound signature, either way they sound ******* incredible. 

 
Could it be because they are slightly lower impedance than the 650s? (300 vs. 250 Ohm).

 

[41Venom14]

   
Could it be because they are slightly lower impedance than the 650s? (300 vs. 250 Ohm).

 
Honestly, I have no clue. I can't imagine 50 ohms being that dramatic of a pitfall. The bass is good, the sound is fantastic, I just can't seem to hear much change when I swap tubes. 
 
Just to clarify, I am not saying the DT 1990 sounds bad on the DV. No not at all, they sound incredibly good.I feel the DT 1990s are slightly better than the HD650s in...honestly...in every way, I am thoroughly impressed. I just can't tell much of a sound change from tube combo to tube combo.
 
I appreciate all the input of ideas, keep em coming, maybe my ears just aren't that great for being 23 and listening to my music maybe a touch to loud and a touch too long lol.

 

[windcar]

 
I have changed my power cord and have quite a collection of 6SN7s, 6AS7Gs and 6080s.
 
With the HD650s, I found the Sylvania VT-231 + Sylvania 6080 to have the most delicious bass. Warm and dripping, with slight extension.

 
Do you find the DV running very hot with 6080s? I had a Chinese tube 6080 and 2 RCA 6080. First the Chinese tube died on me after just a couple of hours of usage. I saw a spark on the inside of the tube and then the right channel no longer have sound. Using the RCA, DV starts emitting a smell similar to a very hot laundry iron just after a couple of minutes of usage. Suffice to say I now stick to regular 6AS7.
I am using the 230V version.

 

[gvl2016]

I do find the amp runs somewhat hotter with 6080s which I attribute to its more compact bottle and heater being closer to the case and less heat dissipation through glass and more through the socket/case. The amp is hot but I can still hold my hand on the top plate and no smell. Electrically they are the same as 6AS7 I think. If yours is abnormally hot it could be due to a gassy tube, they are bad for your amp as they draw more current.

 

[ThermalAlchemy]

I do find the amp runs somewhat hotter with 6080s which I attribute to its more compact bottle and heater being closer to the case and less heat dissipation through glass and more through the socket/case. The amp is hot but I can still hold my hand on the top plate and no smell. Electrically they are the same as 6AS7 I think. If yours is abnormally hot it could be due to a gassy tube, they are bad for your amp as they draw more current.

This is a 1958 RCA 6AS7 running at 274° As seen on the infrared camera consuming 61 W Power

At the time of testing I had some hard dance music with the input volume turned all the way up and the dark voice volume turned all the way up running my HD 650s .
My voltage reference is filtered and protected running through isolated transformers. My power filtering is provided by monster series signature AVS 2000. And my monster power signature series HTPS 7000 .
My 6SN7 is a TUNG-SOL GT , i'll perform the same test using the RCA 6080 will probably have near identical results I've noticed power consumption never really changes unless less you had their original Chinese tubes that Drew 53 W of power when using the Chinese 6AS7 .

 

[ThermalAlchemy]

1961 RCA 6080 temperature 305° but of course in a smaller package with less Glass surface area to dissipate heat in closer proximity to the heat source you would normally have a higher temperature . Power consumption is roughly the same 60.4 W

 

[ThermalAlchemy]

No matter what tubes a test from the 1940s to the 1960s the dark voice always draws roughly 60 W right on the money . This class A amplifier whether I have the music off or full blast barely makes a few tenths of a difference of current draw . As for using infrared camera temperature or the older style infrared with the laser pointer is not actually in accurate method to take tube temperature due to the fact that glass is one of the few substances infrared does not take A accurate temperature of with the curvature of the glass and whether it has a coating on the inside will throw the temperature reading off the only method to truly taking the temperature of clear glass is with a contact thermistor or thermal coupler.

As for the current draw in watts or amps of my reference power center it never moved off 0.8 A no matter what tube combination I threw inside the dark voice .

 

[41Venom14]

   
Do you find the DV running very hot with 6080s? I had a Chinese tube 6080 and 2 RCA 6080. First the Chinese tube died on me after just a couple of hours of usage. I saw a spark on the inside of the tube and then the right channel no longer have sound. Using the RCA, DV starts emitting a smell similar to a very hot laundry iron just after a couple of minutes of usage. Suffice to say I now stick to regular 6AS7.
I am using the 230V version.

 
@ThermalAlchemy, well that was fantastic, thank you for taking the time and breaking out the big guns to answer the question with exactness.
 
You've got a difference of 26 degrees F (those readings are in F right? I cant imagine they would be in Celsius) of 6AS7G vs 6080 by TA's readings. I never worried much about the additional heat from the smaller bottle and I've noticed some tubes get that (to me amazing) smell that says to me its NOS because only my NOS 6080s have gotten that smell.
 
I feel the 6080s pack a wonderful punch and until I get the TungSol 5998, the 6080s are my go too. I've always found the RCA 6AS7G to be quite neutral, almost bright and that doesn't get me all warm and fuzzy haha.

 

[Oskari]

Do you find the DV running very hot with 6080s? I had a Chinese tube 6080 and 2 RCA 6080. First the Chinese tube died on me after just a couple of hours of usage. I saw a spark on the inside of the tube and then the right channel no longer have sound. Using the RCA, DV starts emitting a smell similar to a very hot laundry iron just after a couple of minutes of usage. Suffice to say I now stick to regular 6AS7.
I am using the 230V version.

... I never worried much about the additional heat from the smaller bottle and I've noticed some tubes get that (to me amazing) smell that says to me its NOS because only my NOS 6080s have gotten that smell. ...

Yes, I agree that the smell likely comes from the 6080. The smell will pass but it may take surprisingly long.

 

[gvl2016]

I clean tubes I receive with ISO alcohol, wipe glass and socket. Never had big smell after. There can be an oily film of dirt on the surface from years in storage and it can smell when the tube heats up until it burns off.