microCuts

Glad to hear that and thanks! I can wait as I have temporary case for the amp now.

Is anyone still having an unused/extra case so I can buy one from? Thanks.

Updates for the bass impact imbalance. Played with the L700 earpad before I wanted to send back to retailer. The earpad is removable which is different from the previous lambda model. It is dead simple enough to remove and put it back with the snap mechanism. I can see potential to mod this to enhance the bass by sealing the surrounding ring tighter. On top of the driver there is a loose webbing screen which I do not know what is that really for. Perhaps tighten it up in place can help to improve the bass as well? Who knows... Okay, done with my curiosity and put everything back. Guess what, the bass imbalance is gone and everything works fine! Thus, I can only think of the previous guy who replaced my Left driver didn't put the earpad properly. So that's all about my L700 & modded 007ii. Thanks Birgir and Kevin who brought up this fantastic mod which certainly improve Bass (until the point I'm able to tell bass imbalance), soundstage and also depth(the improvement in depth is greater than soundstage). Special thanks to Insanity as well who helped me to eliminate the amp problem quickly!

Time to update again. Fortunately the L R circuit is simple enough to understand so I swapped a few wires to reverse the both channels. Before I plugged in the L700 I also checked the bias to make sure everything works in reverse order properly understand that a mistake could kill my headphone or maybe myself. So the outcome is, the Left driver still having slightly weaker bass or impact. As I cranked up the volume knob to 3 o'Clock, there is left driver rattling noise again when heavy bass note hits during I put off the headphone...Exactly the same symptom before I swapped the channels. At this point I think I can conclude that my modded 007tii is fine but my L700 is the problematic culprit....Thanks again insanity for the suggested idea!

It's possibly a good idea to figure out the issue. I will see what can I do with the channel swap. Also I will improve the previous circuit cuts with nail polish to ensure no continuity at all. I afraid I cut not deep enough that caused the circuits run wrongly. Thanks insanity.

Still can't figure out what's the potential problem on the amp. I do notice when the voltage swing, both L and R channel will swing similar magnitude. For example, when I set both at 0.5V, the next minute I measure will be 2V. Although both are not very close to 0 but still pretty the same, or balanced. Another potential problem can be from my L700. I sent back to retailer 1 month ago due to Left side of the driver making noise on certain bass note turns out to be dented driver. In fact I noticed the issue the second day I bought it, definitely not caused from my side. So they replaced my Left side driver and the noise is gone. Before I modded the amp, the returned L700 sounds fine, but now I noticed the bass on the Left is slightly less impact, the difference is even greater at higher volume. Modded 007tii did improve bass, depth but my Left driver's bass is still weaker than the right. Can be headphone problem since it is flawed once and not entirely replaced with new phones.

That will be beyond my capability already... I am considering to replace the tubes with matched quad 6S4A. Those I am currently using is matched pairs not sure if this is the problem.

Reworked my soldering and tubes are warmed up more than 20 hours. DC voltage still swing greatly everytime I measure. Not sure if this is normal. And the slight weaker bass (impact) in Left channel is really annoying me..Is there any way to detect channel imbalance on amp other than measuring bias? And I noticed when I turned the volume to 3 o'clock, without putting the L700 on my head, there is kind of mechanical vibration noise when the bass note hits on Left driver. Right driver is totally fine though.

Ok, found my answers for my previous questions and modded my amp yesterday. Now my modded 007tii is running quite fine I guess, no smokes and humming etc etc. However I find the biasing process is not as smooth and easy because the wild voltage swing, I could get 300-500mV at one point then the next minute when I measure it become >1V. For your information my tubes are not matched quads, only 2 pairs of matched pair per each channel which I bought new online. Is that normal that the swing is so great? Or my bad soldering skill.... And because of my considered half done biasing I noticed that the right channel is slightly louder (more bass, more sparkles). Really slight not sure if that is my psychological play.

Just opened up the amp again and draw out the cathode circuit, it is exactly the same as the 007t. Since now I have the proper schematics for Cathodes and Plates to visualize easier, I have a clearer picture where should I rewire. And this also helped me a lot to understand Spritzer's latest rewiring snapshot, now I know why some of the components are removed to ease the rewiring Removed components are :2x 100 omh resistors. And a Pot (TVR4/3). However, I still have some questions though. 1.) For the Cathode part, Spritzer mentioned it is to be connected to TVR2. However I figured out that there is a 1.5k resistor before it. Should I bypass it or remain it before TVR2? 2.) Let say my unit is successfully modded to be able to use 6S4A tubes. Is there any impact on the bias adjustment process? Thanks!

So I opened the amp again and try to draw the Cathode circuit. This is what I got: And it looks quite identical to the dual tube schematics KG posted here except that the resistor values are different..This is my first time interpreting electronics stuff that detailed because of Stax! And regarding the Q17 Q18 part number, the labeling is C1815 B4 4F if I am not seeing wrongly.

Just check opened the up amp again and compare. Noticed that there is difference between 007t schematics and my 007tii amp. Not sure if I interpret them wrongly.. Is this what you mean in your previous post? However I cant find any 200 omh resistor around the tube, not even the label... And i noticed components from Pin 3 & Pin 8 to TVR2 in my 007tii is quite different from the schematics. My amp has transistor, 4~5k resistor, 2x 1.5k resistor but doesnt have the 200 resistor...

Ok. Just had a quick look. One question, I managed to find only 1 resistor & 1 pot to be bypassed which is differ from 2 resistors & 1 pot mentioned by Birgir..? Now that explains why Birgir removed TVR3 & TVR4 in his latest Modified 007tii wiring snapshot....

Wow! A full high res schematics for 007t! I need to read the whole thing again now. That will make things more clear. Thanks Birgir & KG!

I just tried to google around but couldnt get the schematics at all. Found some other Stax amps but not the 007t. However I found T1 which is similar to 006t. 006t used 2 tubes though.. Lets ignore the 6FQ7 tube, think you are suggesting me to skip 2 resistors and 1 Pot for each tube, therefore the 2 resistors and 1 Pot is remained unused in the circuit? Thanks!

"Internally connected pins means you can use either one so no worries." If my understanding is correct it means Pin 3 & Pin 6 is connected internally in the tube therefore no external wiring is required. I guess the best way to check continuity between Pins is to put on all the 6S4A tubes during modification? "Otherwise it is just grid to grid, anode to anode.." The 6S4A pins layout consists only 1 pair of internally connected pins which is Pin 3 & Pin 6. Think this is what you were referring. "but with the cathode I always bypass the balancing circuit next to each tube." I don't understand this. Do you mean I can skip the Cathode 2 and connect to Cathode 1 directly?

Hi All, I would like to mod my SRM007Tii so that it can use 6S4A tubes. However I am almost new in messing around with electronics circuit. Need some guidance from you all. Pictures below show my 007Tii board with re-routing & termination labels (Incomplete). I took quite sometimes to compare snapshots available online posted by Spritzer & Justin. All of them have slightly different wirings. The one I understand the most is the one Spritzer posted for the first time, so my preliminary outcome is similar to his one although it is still incomplete. Therefore I would like to clear my doubts before I start messing around with the PCB. This is my guidance to get the idea where should I re-wiring to. I also have a fluke 175 to check the continuity between 2 points. The Back part of the PCB Q1: For the Yellow wiring, can I skip the plate 2 and connect directly on plate 1? Q2 : According to the Basing Diagram Pin 3 & Pin 6 are linked. Can I wiring Pin 6 to Pin 3 or vice versa? (Example drawn on Left Bottom tube) The Top part of the PCB I cant find much info about the Mod on the top of the PCB. Logically some traces should be cut for termination. Please kindly advise if I labeled them correctly. Hopefully my understanding (routing wise) is good enough so I can proceed further. I am really new in this therefore alot of questions popped on me. The safest way for me to have this successfully modded is to fully get to know how to convert 6CG7 routing to adapt 6S4A tubes plus some really careful soldering jobs. In terms of technical I have no idea at all..

I pulled the trigger on the L700...makes no sense get the 009 with really mediocre DAC & amp. Better use the rest of money to invest in better DAC or Amp. Right out of Mojo & 007tii, the L700 is easily the best sounding headphone I have owned to date, compared to my previously owned AKG Q701, HD650, LCD3, and MrSpeakers Ether. The smoothness, separation, airiness, and detailed are reasons why I stopped looking other type of headphones than estat. Planars may win in bass slam but the overall imagination is way too 2D. I auditioned similar setup before I went home but with different DAC that is Resonessence Labs Invicta and the result is even more stunning. Wider soundstage, better bass, and overall speedier. Source is definitely my next upgrade. And for the 007tii, I will mod it perhaps in next couples weeks. I already extracted all the possible information from headcase/headfi month ago. I understand the logic of the mod, basically is to retrace the board so it is able to use 6A4S tubes which has different pinouts than 6CG7. The only thing slightly concerns me is I have very little experience in doing job like this. Quite shameful to speak it out as I am a Mechanical Engineer though...Anyway I will have questions which Spritzer could answer me when I am ready for the Mod, hope that you dont mind.

Hi spritzer bro, Just curious why haven't you listen to L700 yet?

Hi Boss, Do you mean the latest one is better than the "early" mk II? The one I listened recently is most probably the latest revision which I find not bad at all. My eyes opened after I switched from 009/L700 to 007 mkii thought it will be the worst according to many forumers but in fact it has totally different sounding which leads to another great experience. Sometimes I wonder why 009 alone not 007+L700 together for best of both worlds and still have some pocket changes for something else haha.

Sounds like the weak cable entry is the only issue which is unfix-able. Still have no decisions yet though. But at least I know a new SR-009 is more future proof. Thank you all of you!

Hi Master Spritzer, I roughly went through Ebay and found some of the parts for 007 but not sure if they are compatible with the old 007 mk1? The accessories is not cheap though Another very specific and difficult question. How long for a brand new pair 007 mk1 to have the parts worn out? The product photo sent by my seller seems quite mint. He includes me a spare new pad as well. Having stax amp sitting there without headphone is killing me...

Hi Spritzer, May I know what is the potential issue that I may face from a SZ1? This is the Serial number that seller offering me. SZ1-1089. Not sure if you guys has any idea on this batch. Thanks. I had actually auditioned SR009, SR007 mkII, and SRL700 from a SRM007tii. L700 is a baby version of SR009 but the bass is abit soft and lack of extension that I always enjoy of. SR009 is perfect for me but its so pricey that holding me back. SR007 mkII is warm and thicked sound which is quite enjoyable in certain gerne especially vocal. I owned a SRM007tii too due to great used price but do not have a stax headphone with me now. I know its a mediorce amp but I can mod it to use 6A4S tubes. I have two matched pairs 6A4S I planned to mod in future. SR007 mk1 is the only one I have not listened to before therefore buying a used pair is almost like betting blindly. Need some advice from experts here. 40% Rocks (Post Rock / Alternative Rock) 30% Vocals (Pop / Acoustic) 15% Jazz 15% Electronica + some weird stuff.

Hi All, I am looking to buy an used SR-007 mk1 which is considered the best in Stax community. Some one offering me with the SR-007 SZ1 not the one with serial number 7xxxx I am not sure is this the "Best" version of the 007. Is this worth to get? Thanks!

Haha..would you elaborate more on this? I am quite curious about this as an owner of Ether. I am quite a newbie in this hobby therefore I am not sure how Ether ranks in the entire list of products out there. I only have long enough experience with the LCD3 which I think is very enjoyable but I sold it due to the poor comfort.