[gamefreak054]

Project Ember Tube Rolling​

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UPDATES:
2/5/2014- Blackburn Mullard 12AT7, France Philips Miniwatt 12AT7, and Holland Bugleboy 6DJ8
2/2/2014- Other Members Impressions Section Added
 

 ​

Intro:
I just received my tube amp and did several hours of tube rolling. I could not decide if I wanted to do this or not, but after seeing that nobody had written about some of the tubes I was using on this amp I thought it may be helpful. I will be somewhat short and concise with each tube as I am not the greatest at describing the sound I am hearing, but my brother and my dad did confirm the same things I thought about the tubes (both being audiophiles as well, and these are my dads tubes). If you feel that one of my tubes descriptions is off. Feel free to question me, and I can go back and try it again. However some of these tubes my dad is only letting me listen to once due to the expense and/or rarity. If you need some clarification on tube models, let me know and I will get it clarified.
 
Tubes Accepted by Project Ember:

Spoiler: Warning: Spoiler!

6V TUBES:
6922
7308
8223
6AQ8
6DJ8
6N1P
6H23
6H23N
6L12
6N11
6N23
B719
Cca
CV2492
CV2493
CV5358
E88CC
E89CC, E188CC
E189CC
E288CC
ECC85
ECC88
ECC89
ECC188
ECC189
ECC288
ECC289
JAN 7308
12V TUBES:
5751
5814
5814A
5963
6189
6201
6681
7025
7058
7729
6L13
12AD7
12AT7
12AV7
12AU7
12AX7
12DF7
12DM7
12DT7 A2900
B152
B309
B329
B339
B749
CV0455
CV0491
CV0492
CV4024
12V TUBES CONTINUED:
E181CC
E182CC
E183CC E283CC
E811CC
E812CC
E813CC
E2157
E2163
E2164
ECC81
ECC82
ECC83
ECC181
ECC182
ECC182
ECC801
ECC803
ECC803S
E81CC
E82CC E83CC

 

 
Set Up:
Anyways I tested 16 different tubes being a variety of 12AT7, 12AU7, 12DF7 (I will talk about this one later), 6N1P, and a 6DJ8. I tested each tube for about 30 mins, along with my brother and my dad listening to what I was listening to and pretty much confirming what I was listening to. Some people may say 30 min may not be enough to warm up the tube, but I did not hear any recognizable difference after 5-10 min of listening. Also some tubes were listened to much more than 30 min.
 
My set up was my DX100 (set at around 220 volume), using the line out (3.5mm to RCA), and using either the Alpha Dogs or my modded woody SR60is. The amplifier was set up at high gain low resistance for the Alpha Dogs and high gain, high resistance for the Grados. 
 
The common songs (check spoiler for videos) used  across all tubes were: Wintersun Time I: Sons of Winter and Stars for the amazing amount of instruments used in the recording, the variety of high, mids, and bass, great for testing along with it being an great recording. Metallica Black Album: The Unforgiven for its clean sound, and overall just a great rock song.  Daft Punk RAM: Get Lucky for being an ok recording, along with being a decent song for pop and techno.
 
All songs were FLAC 16 bit 44.1 khz files ripped from CDs.

Spoiler: Warning: Spoiler!

 

 

 

 
 

 

Tubes​

12AT7 Family:
 
Sylvania Triple Mica: This tube had good detail, but I found the Mids and Bass a bit lacking. It was definitely a tube that had a good amount of treble. It was probably my favorite tube for treble as it had the best musical sound without being dull. I found the instrument seperation to be decent with this tube. This was not a great pairing with the grados due to the extended treble. The overall sound of this was  a bit harsh, but not as harsh as some of the other treble tubes I have used.
 
Standard Sylvania: This was an ok all rounder tube. It was a decent flat presentation with ok detail, but not as much as some of the other flat signature tubes. It seemed to maintain the musicality of the triple mica, but a much more tame tube overall. Nothing about this tube was sparkly. It just ended up being an solid ok tube all around. Probably a good tube if you wanted a cheaper flat tube.
 
Telefunken: This was by favorite tube of the AT7 family I tested. It had the best details of all the tubes listed. It did not do anything bad nor did it do excel at any one thing (other than detail). It was my favorite flat tube, and probably the tube I will use the majority of the time. I did find the treble could be a bit harsh at times, but I think that is mostly due to the detail. My brother found this tube to be a bit tinny sounding, and my dad found the bass a touch lacking. However neither bugged me too much. As I found its other traits to pay off. This tube also had a really crisp sound to it. Just an great balanced tube over all.
 
GE: I personally did not like this tube at all. It seemed to have almost a slow decay to it. Along with a decent amount of sibilance. Had pretty bad mid range detail, with grainy sounding mids. It had ok treble, but was a bit harsh for my ears. It also had a decent amount of bass to it, but some of the other tubes had better bass.
 
Philips Miniwatt: Exactly what I wanted. This tube has the same construction as a Holland Philips tubes aka Amperex Bugle Boys I praised so well below. Well this tube has the exact same detailed airy smooth sound that I was searching for. The musicality on these is king to my ears. I highly recommend these.
 
Mullard Blackburn: I still am not the hugest fan on the Mullard tubes. They do an excellent job at mid range details, but I still find other parts of the sound signature lacking. It does have decent detail, but they do not match the musicality of the Amperex/Philips tubes. 
 
12AU7 Family:
 
12AU7A RCA Clear Top: Admittedly I hated this tube. I found it pretty hollow sounding, and dull. It had poor bass and was lacking mids. The best thing about this tube was the treble, but I felt like there were other tubes that did treble much better.
 
Mullard CV4003: I found this tube a bit lacking in bass with poor mid range detail. However it had good details and good treble with little sibilance. Overall I found this a decent tube despite it not excelling at anything, and having some faults. I found it to be an easy listening tube.
 
Family Notes: These tubes are probably not full optimized in this circuit as they sounded slightly dull. My dad stated that they did not carry all the characteristics from when he used it in his MC60 amps.
 
 
12DF7 Tube:
 
Westinghouse: This was an great tube. It had good detail, but less than some of the other very detailed tubes. It shared a lot of the qualities of the Telefunken. It was well balanced. It had a bit better bass than the Telefunken, with an airy quality. In my opinion this an easy listening version of the Telefunken. If you felt like kicking back and did not want to listen to all the details, this would be the tube to put in. 
 
Family Notes: This is most likely a very hard tube to find. My dad stated it was a very strange tube he found on ebay, and bought a quad to test. He did not like it in his MC60 amplifiers, but really liked it in the ember. So the circuit in the ember may have good optimization for this tube. This tube is supposed to be a cross between a 12AX7 and a 12AT7 I believe (it could be the 12AX7 and 12AU7 if I am not remembering correctly). I am not sure if any other companies developed these tubes.
 
 
12AX7 Family:
 
Tesla E83CC: This tube had reduced treble, but had a great mid range to it with very good mid bass punch. It did not excel in either bass nor treble. This would be a great tube for someone who loves mids.
 
Mullard CV4004: This particular tube was amazing with Daft Punk. This would be the tube to buy if you wanted an upgraded Mad Dog sound signature and owned the Alpha Dogs. It gave it a bit darker presentation, with good mids and decent bass. It was lacking a bit in treble, with a bit more sibilance than other tubes. The sound stage sounded a bit reduced. Overall this was a decent sounding tube.
 
GE Longplate: This tube did not seem to excel at anything. It had poor separation and lacked detail. It had ok treble, but I would not purchase it for the treble as there are better tubes out there for treble. I personally would not recommend this tube.
 
RCA Black Plate: I found this tube to be a bit lacking in the mid range. It was a very harsh and dry sounding tube. I thought it had decent instrument separation. I did have great treble. This overall tube gave my Alpha Dogs the presentation of the AKG K701 (in which I am not the biggest fan of). Even though it was not my favorite it would probably be a great match for some one who loves treble.
 
Standard 1970s RCA: This tube had good midrange, but had poor separation and soundstage. It had decent detail and treble. However it had a decent amount of sibilance. This is an ok tube, but there were others that I liked better.
 
Mazda III-8: This tube had the best bass of all the tubes. So if you wanted a bassy tube this would be the tube for you. It had decent mids. The biggest downfall of this tube was the treble as it was harsh and sibilant.
 
Holland Amperex Bugle Boy: This was my favorite tube of all the tubes I tested. Sadly I can not keep or use this tube ): anyways this was the only tube that matched the Telefunken in detail. This tube had decent separation with good treble and mids. The bass was a bit lacking. This tube had the airiest sound of all the tubes by far. It was a very smooth sounding tube over all. I highly recommend this tube if you can afford one.
 
 
6DJ8 Family:
 
GE: This tube was pretty harsh with a good amount of sibilance and lacking treble. However it had good detail, and good mids including the midbass. It has a slightly poor separation overall. It had decent bass quantity as well. Overall a solid tube that really had some positive traits to it.
 
Holland Amperex Bugle Boy: This tube share a decent amount of similarities of the Philips 12AT7 and Bugle Boy 12AX7 however I did not find it as airy as either of the tubes, nor as smooth. I also did find that the bass was not as good and was not as punchy. However I did find a sweet spot on the volume pot where the tube did sound a bit better. I tested this on both the Grados and the ADs, and still preferred the 12AT7 and 12AX7 tubes. To be fair though, it is hard to match volume of two different gain tubes.
 
 
6N1P Family:
 
Gold Grid: This is the stock tube that the amp was shipped with. I got to admit it was a bit of a disappointment. I personally did not like the sound signature of this at all. This had the warmest sound of all the tubes, with poor instrument separation. The mid range was ok, but I found this tube to have poor detail. I personally recommend buying a different tube to use with your Project Ember.
 
 

My Tube Rankings (from best to worst):​

Amperex Bugle Boy 12AX7​

Telefunken 12AT7​

Westinghouse 12DF7​

Sylvania Triple Mica 12AD7​

GE 6DJ8​

Mullard CV4003 12AU7​

Standard Sylvania 12AT7​

Tesla E83CC 12AX7 tied with Mullard CV4004 12AX7​

Standard RCA 12AX7​

Mazda III-8​

RCA Black Plate 12AX7​

GE Long Plate 12AX7​

GE 12AT7​

Gold Grid 6N1P​

RCA CLEAR TOP 12AU7​

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Other Head-Fi Member's Tube Impressions​

(If you do not want your impression added just say so in your post)​

@Johan-71: 
6DJ8 Amperex Bugle Boy- Smooth with huge soundstage
 
6DJ8 Amperex Orange Globe- Slightly less soundstage than the Bugle Boy, but was slightly clearer with a touch more details.
 
@rmouser :
12AX7 Sylvania Triple Mica 5751- An industrialized 12AX7 (gain 100) with a gain of 70. Due to higher gain, this one emits a 60 HZ constant level hum. A GE 5751 was not as prone to do that. To remedy that, I made a tube shield out of aluminum foil and slipped it over the tube--noise gone. This one produces a very robust, dynamic sound, much like solid state with the tube benefits.
 
12AX7 Amperex 6201- is very warm and liquid with a tight although not powerful bass. Mids are very warn and highs mellow. It is a very "tubey" sound. The imaging seems like being in a sound proofed chamber, being surrounded by the instruments.
 
@connieflyer:
Tungsram E80CC-Good range,stage is a bit narrow
 
Westinghouse 12au7/ECC82 black carbonized plates tube raised []-getter- best so far, good sound, stage
 

 

[Asr]

Originally Posted by gamefreak054 /img/forum/go_quote.gif
My set up was my DX100 (set at around 220 volume), using the line out (3.5mm to RCA), and using either the Alpha Dogs or my modded woody SR60is. The amplifier was set up at high gain low resistance for the Alpha Dogs and high gain, high resistance for the Grados.

 
Not sure why you were using those gain & resistance settings. You should use low gain whenever possible, unless it doesn't provide enough headroom on the volume pot, and low resistance in general for low-impedance headphones. Settings for the Alpha Dog should have been low gain & med R (for maximum output power), and for the SR60i low gain & low R. Not using those settings probably skewed your results, as low R increases general sonic transparency of the tube. Increasing the output resistance causes increasing loss in transparency.

 

[gamefreak054]

   
Not sure why you were using those gain & resistance settings. You should use low gain whenever possible, unless it doesn't provide enough headroom on the volume pot, and low resistance in general for low-impedance headphones. Settings for the Alpha Dog should have been low gain & med R (for maximum output power), and for the SR60i low gain & low R. Not using those settings probably skewed your results, as low R increases general sonic transparency of the tube. Increasing the output resistance causes increasing loss in transparency.

I think you have some logic mixed up. The grados would need low gain high resistance for the lowest power output and most tubey sound. The reason I did not change it is because changing the gain is a little more inconvenient than changing the resistance. Low gain and low resistance is a heck of a lot power for the grados.
 
For the Alpha Dogs, low gain works but I like the sound of the extra power. Lowest resistance gives the most power. Low gain and medium resistance would be just below optimal recommended power output for the ADs (optimal power is supposed to be 1.5wpc) . It probably is not that drastic, but after playing around with settings having the highest power possible was my favorite. To confirm what I am talking about check the chart Jeremy made. The resistance does make a difference in how much tube sound you are hearing, but that does not go without saying that the tubes still make drastic changes even on the lowest resistance settings.
 

 

[connieflyer]

You should post this over on the Project Ember page on DIY Audio Heaven they are active with this amp.  http://diyah.boards.net/.................
http://diyah.boards.net/thread/143/project-ember also they have a page on tubes here...http://diyah.boards.net/thread/366/

 

[gamefreak054]

  You should post this over on the Project Ember page on DIY Audio Heaven they are active with this amp.  http://diyah.boards.net/.................
http://diyah.boards.net/thread/143/project-ember also they have a page on tubes here...http://diyah.boards.net/thread/366/

Thanks for the suggestion. I knew about that site (and is where I read a lot of information on this amp), however I am not sure if I would be very active over there. I would hate to make an account just to make a couple of posts.

 

[Asr]

I think you have some logic mixed up. The grados would need low gain high resistance for the lowest power output and most tubey sound. The reason I did not change it is because changing the gain is a little more inconvenient than changing the resistance. Low gain and low resistance is a heck of a lot power for the grados.

 
I'm confused as to why you would intentionally want to effectively decrease the power output into the Grado and get a less linear sound as far as the tube is concerned. Usually the goal is to maximize the output power into a set of headphones, not to intentionally minimize it. It's not like you'd be able to "overdrive" the Grado from too much power either, it'd use only as much as needed.
 
And increasing the gain just increases a multiplier, it doesn't actually cause more power output by itself.

 

[gamefreak054]

   
I'm confused as to why you would intentionally want to effectively decrease the power output into the Grado and get a less linear sound as far as the tube is concerned. Usually the goal is to maximize the output power into a set of headphones, not to intentionally minimize it. It's not like you'd be able to "overdrive" the Grado from too much power either, it'd use only as much as needed.
 
And increasing the gain just increases a multiplier, it doesn't actually cause more power output by itself.

You may be right about the gain I have to look into that.
 
However the grados are decently efficient. Putting over a watt into the headphones is not going to give you volume control when you need less than half that. You can drive them to dangerous levels with a lot of power because they simply can not use that much. On another thread someone claimed that they emailed grado and they recommended not to use anything over 500mw.

 

[Asr]

However the grados are decently efficient. Putting over a watt into the headphones is not going to give you volume control when you need less than half that. You can drive them to dangerous levels with a lot of power because they simply can not use that much. On another thread someone claimed that they emailed grado and they recommended not to use anything over 500mw.

 
Volume isn't the same thing as power, and all amps are made to output only as much power as the headphones need. Sure, you could theoretically blow out most headphones if you took them off your head and cranked up the volume to max with loud music, but as long as you keep them on your head, your ears' volume level tolerance will prevent that from happening, as you'd blow your hearing well before you blow out the headphones.
 
The power output specs for amps are a maximum capability figure and don't mean that the amp is ever "forcefeeding" something on the order of 1.4W (or whatever else the spec may be) into 32 Ohm headphones all the time. And as it applies to low-impedance headphones specifically, "power" is usually meant as "current" (as it becomes the overriding factor versus voltage) and high-current reserve capability is necessary to optimally drive low-impedance headphones. Limiting that reserve capability can cause low-impedance headphones to be under-driven—if they suddenly need current and the amp can't supply it, it results in clipping (which can actually cause damage to transducers, especially in the case of loudspeakers).

 

[gamefreak054]

   
Volume isn't the same thing as power, and all amps are made to output only as much power as the headphones need. Sure, you could theoretically blow out most headphones if you took them off your head and cranked up the volume to max with loud music, but as long as you keep them on your head, your ears' volume level tolerance will prevent that from happening, as you'd blow your hearing well before you blow out the headphones.
 
The power output specs for amps are a maximum capability figure and don't mean that the amp is ever "forcefeeding" something on the order of 1.4W (or whatever else the spec may be) into 32 Ohm headphones all the time. And as it applies to low-impedance headphones specifically, "power" is usually meant as "current" (as it becomes the overriding factor versus voltage) and high-current reserve capability is necessary to optimally drive low-impedance headphones. Limiting that reserve capability can cause low-impedance headphones to be under-driven—if they suddenly need current and the amp can't supply it, it results in clipping (which can actually cause damage to transducers, especially in the case of loudspeakers).

Alright, I more so get what you are saying now than what you were saying before. However the question I have then if this is true how do you know that you are limiting the reserve capability of the grados at the high resistance setting? I get that lowering the resistance setting would minimize the potential of inducing the clipping, but I guess the million dollar question for me is when would the clipping even start in the first place? When does current reserve become overkill? Plus it still does not seem that you will get that great of volume control at the lower resistance settings. The grados get loud pretty fast even at the high resistance. Even by looking at the charts you can see that the power is 4x the output or higher. 

 

[Asr]

Alright, I more so get what you are saying now than what you were saying before. However the question I have then if this is true how do you know that you are limiting the reserve capability of the grados at the high resistance setting? I get that lowering the resistance setting would minimize the potential of inducing the clipping, but I guess the million dollar question for me is when would the clipping even start in the first place? When does current reserve become overkill? Plus it still does not seem that you will get that great of volume control at the lower resistance settings. The grados get loud pretty fast even at the high resistance. Even by looking at the charts you can see that the power is 4x the output or higher. 

 
Looking at the 120 Ohm curve, you can see that it outputs up to ~300mW @ 32 Ohms. The 500mW you mentioned earlier is probably a "maximum input power" rating, which means that the SR60 will take up to that amount of power before it breaks (all that means is that there's a point where you'll break the headphones if you turn up volume high enough on loud music, and the amp can still supply enough current at that point—you should never reach that point as long as you're listening at ear-safe volumes though). In short, the Project Ember set at 120 Ohms will be unable to supply maximum input power (i.e., enough current) into the SR60 whenever the headphones might need it, and the clipping would likely manifest itself most obviously on loud bass notes. Setting the amp to 35 Ohms obviously solves the issue, but 0.1 Ohms would increase the sonic linearity (i.e., transparency) to maximum and really let you hear the sonic effect of the tube. Generally, it's far better to have overkill current reserve than not enough. No one can complain about overkill.

 
If you need even lower gain than what the amp can offer with low gain & low R, rolling in low-gain tubes can help, like 12AU7, 5814, or 5963 types. Most of the tubes you tested (the 12AX7s, 12DF7s, & 12AT7s) are higher-gain tubes and are much better used with high-impedance or inefficient headphones like the upper-end Sennheiser & Beyerdynamic models or other models like the AKG K7xx/K340/K1000 and the Audeze & HiFiMan planar magnetics. For better results with low-impedance headphones, you want to be using either 6V tubes or the aforementioned 12AU7/5814/5963.

 

[LoveKnight]

Wow. There are so many rules, ways to drive headphones. I usually want to make it simple, try every configurations and then choose the best that suits my ears. End my story

. By the way, this could be a great thread. I am going to save money to purchase an Ember or Ember II in the future. Cheer guys.

 

[gamefreak054]

   
Looking at the 120 Ohm curve, you can see that it outputs up to ~300mW @ 32 Ohms. The 500mW you mentioned earlier is probably a "maximum input power" rating, which means that the SR60 will take up to that amount of power before it breaks (all that means is that there's a point where you'll break the headphones if you turn up volume high enough on loud music, and the amp can still supply enough current at that point—you should never reach that point as long as you're listening at ear-safe volumes though). In short, the Project Ember set at 120 Ohms will be unable to supply maximum input power (i.e., enough current) into the SR60 whenever the headphones might need it, and the clipping would likely manifest itself most obviously on loud bass notes. Setting the amp to 35 Ohms obviously solves the issue, but 0.1 Ohms would increase the sonic linearity (i.e., transparency) to maximum and really let you hear the sonic effect of the tube. Generally, it's far better to have overkill current reserve than not enough. No one can complain about overkill.

 
If you need even lower gain than what the amp can offer with low gain & low R, rolling in low-gain tubes can help, like 12AU7, 5814, or 5963 types. Most of the tubes you tested (the 12AX7s, 12DF7s, & 12AT7s) are higher-gain tubes and are much better used with high-impedance or inefficient headphones like the upper-end Sennheiser & Beyerdynamic models or other models like the AKG K7xx/K340/K1000 and the Audeze & HiFiMan planar magnetics. For better results with low-impedance headphones, you want to be using either 6V tubes or the aforementioned 12AU7/5814/5963.

Alright thanks for the info. I did know about the tube gains though. Bringing that up the 12au7 tubes I rated might not be the most accurate reviews, as I used my alpha dogs to judge those. Which are inefficient planars. It still did seem like the ADs had enough power though while cranking up the volume, and their sonic qualities did not change at said volume.
 
However I thought low resistance had the worst tube sound, or to put in other words the tube was the most transparent and high resistance had the least tube transparency? I remember reading this is several different reviews.
 
@LoveKnight I am glad it helped you.

 

[Johan-71]

Nice work/writeup.
My no.1 tube this Week is a 6dj8 buggle boy, with large halo getter. I'm waiting for my early -50 with D getter from a local shop to show up.
I can also recommend 6dj8 amperex orange globe, it has almost the same huge soundstage as the bugle boy. But to my ears it's a little bit clearer, the bugle boy is a tiny bit smoother.

 

[gamefreak054]

Nice work/writeup.
My no.1 tube this Week is a 6dj8 buggle boy, with large halo getter. I'm waiting for my early -50 with D getter from a local shop to show up.
I can also recommend 6dj8 amperex orange globe, it has almost the same huge soundstage as the bugle boy. But to my ears it's a little bit clearer, the bugle boy is a tiny bit smoother.

Cool, I will have to look into those. I do want to find my own amperex tube. The detail and airy smoothness of the bugle boy 12AX7 was amazing.

 

[Johan-71]

Then you will probably love the orange globe, still smooth but a little more details. I've seen it on fleabay at low prices, don't now about quality...