Suitable alternat for SED wing = c= ?

[bandit2013]

I was able to squeeze the TAD6L6GC into the Mark IV. It was not the length of the tube, more so the thickness of the pins and the length of the boss or key which was the issue. With the MC90 speaker this would not be an issue. I was not impressed with the TAD in the Mark IV. They sounded thin on the lead channel. Had to double check to see if I moved the speaker from 8 ohm to 4 ohm by accident. Also needed to verify if the lead mode was set to triode or pentode. These tubes sounded better in the Mark V since I believe it runs hotter than the Mark IV. I could have channeled it though the 412 just to compare tone to the Mark V. Everything sounds better thought the 412 than a single 12. I also have to consider that all the tubes I have ordered were requested for use with the Mark V. Probably should not matter but I believe the two amps may not share a common bias point. Comparing the schematics between the Mark IV and the Mark V, there is quite a difference on the power amp circuit. Phase inverter circuit is not the same either.

Tube that I do not rate well for the Mark V sound better in the Mark IV. The 6CA7 for instance seemed a bit muddy in the Mark IV. Perhaps a bit too cold for the 6CA7. EL34's did not favor well in the combo amp either (EL34 and its cousins can only be used on the outer sockets).

Thinking of integrated quads, I mixed up the EL34 in the center and 6CA7 on the outer positions on the Mark V. Just as I though, the inner tubes will set the overall tone. Outer tubes will not influence much.

 

[bandit2013]

At the moment I am running the TAD6L6GC in the Mark V. It is difficult to choose 6CA7 or the TAD. They both sound great.

I talked with the person who I sold the Mark III amp too. I was wondering if they still had the original tubes I provided. Status of the tubes were unknown at the time I gave them. I did state that they may be of no use but if they could be used as reference for tube replacement.

Old Mesa 6L6GC (from the 80's) These retired tubes look very similar to the TAD in plated design, there are no openings on the sides of the plates. The getter is a dual halo placed on the plate studs at a 45 degree angle. The tube is also marked USA on the glass and on the base. Hard to make out the Mesa Logo and STR#, appears to be STR415.
The large bottle EL34 tubes that came with the Mark III are also marked with 6CA7. Glass tube and base are also marked USA. Mesa STR really hard to read. Could be 410 or something close. Dual getter design but pancake shaped. Plates have three medium sized circular cutouts. These were my favorite tubes. Too bad they are no longer of any use. Along with the old tubes, I also received the skinny Mesa STR440 EL34/6CA7. This tube has two large cooling fins on the grid posts. Single halo getter. As I remember, they sounded good but not as good as the large bottle 6CA7. It is interesting to take notice to the changes over time on the tubes.

 

[R_ADKINS80]

I just got a sextet of the JJ 6CA7 today in the mail. I hope they sound as good as all the reviews I have read.

 

[bandit2013]

They made a big different in the Mark V, all channels and all voice modes. I was using the TAD6L6GC for a while. They are good too. However, I like the JJ6CA7s more. Also, broke one of the plastic key post on a TAD tube. I was able to fix it with jewelers adhesive. Key broke when I removed the tubes after trying them out for the first time. I did have other various preamp tubes in the Mark V. Tung sol and EH sounded good up to a point. Returned all preamp tubes to stock mesa 12ax7's. For now they are quiet compared to the TS or EH tubes. I did get 3 Mullard re-issue tubes. Only one was quiet, the others tended to vibrate a bit. When you hear the tube rattle thought the speaker, that can be annoying. With the Mesa 12AX7 (I believe they are same as jj12ax7) all channels are quiet (no guitar signal, all settings at 11:00 on Mark V). There is a slight hiss on CH3 in extreme mode but not too noticeable. I did have some old Mesa Chinese 12ax7 from the Mark III (tubes were from the 1980's). Those were super quiet, they also sound good too but can get a little fizzy with boosted gain. The mesa 12ax7 tubes sounded the best with the JJ6CA7 and the TAD6L6GC-STR. I could not stand them when I had the SED 6L6GC =C= due to brightness, it was worse with the TS7581. Absolutely terrible with the Mesa 6L6GC. I am not fond of ice picking. Even the EVM12L(bl) speakers would not mask the ice pick. It was difficult to tune it out even with preamp tubes. I can still get that bell tone chime with the 6CA7 but it remains smooth and seems to stay out the harsh brittleness common to a 6L6GC tube. The JJ6CA7 has some similarities to a 6L6GC tube such as a beam forming plates. They are the best sounding EL34 tubes. The old tubes I had from the Mark III days, they were Sylvania 6CA7/EL34 branded tubes. Those sounded the best, when I had to replace them I could not find them an had to settle to the skinny bottle type. I almost wish I still had the Mark III now that the 6CA7 have been revived. The EH6Ca7 has been available for some time, I believe they are not quite the same in character as the JJ6CA7.

I hope they sound good in the triple rectifier for you as they do in the Mark V.

 

[R_ADKINS80]

OK, after playing the crap out of these JJ 6CA7 all weekend at different volumes and bias settings I have come to one conclusion. All the money I have spent on power tubes in the last few years has been wasted. Everything from EL34 up to 6550, these blow them all way. I honestly can't see myself using anything else from now on. The harmonics on these babies are out of this world. They cut like a knife in a mix and the amp sounds killer no matter how you dial it in. Highly recommended !!!! YMMV

 

[swbo101]

OK, I'm sorry if this is a stupid question, but I'm just not that familiar with the 6CA7. Is this an EL34 or a 6L6? The reason why I'm asking is that I have a MarkIV. Can these go in all the sockets (inner and outer) or just the outer like the EL34's.

Thanks.

 

[jnoel64]

The 6CA7 is an EL-34 bias. But the tone is more like a blend of EL-34 and 6L6. I would never recommend using a 6CA7 on a 6L6 bias setting.

 

[swbo101]

The 6CA7 is an EL-34 bias. But the tone is more like a blend of EL-34 and 6L6. I would never recommend using a 6CA7 on a 6L6 bias setting.

Thanks, I asked b/c in my amp manual it mentions different tube types that can be swapped out in certain positions, but 6CA7 was not one of them.

Much appreciated!

 

[bandit2013]

Equivalent tubes to EL34: 6CA7 (direct replacement, Mesa used them in the Mark III labeled as both 6CA7 and EL34). The other option is KT77 but will require more heater current, not sure if suitable for all amps that are capable of running EL34 type tubes. KT77 are bright like 6L6 and not as deep as 6CA7. There is also EL34B, EL34L (deeper bass version that is available not should not be used in Mark V due to 10W mode). There is a good description on Eurotubes web site as well as other sites that sell tubes.

The Mark IV runs the outer most tube positions on the hot side. If you still have the manual (if not download it from Mesa), the outer tubes can use EL34. The inner pair can only be 6L6 (or its equivalents).

I did try the 6CA7 on the Mark IV outer sockets. It was a bit darker than the 6L6. I have grown fond of the EH EL34 in the outer positions and Tung Sol 7581 on the inner. The TS is bold and can be bright but lacks the harmonics that the SED wing C generate. The EL34 sounded thin in the Mark V but works well in the Mark IV with the 7581 on the inner. The 6CA7 is an EL34 but different. 6CA7 uses EL34 bias, but sounds more like and EL34 combined with 6L6 tube. Deep low end and harmonic tones of an EL34. Top end will still be bright because the inner 6L6 tubs parallel the outer tubes when using SimilClass mode. Also depends on speakers too.


Mark IV tube choices:
All 6L6, can use all power modes, class a, Simil Class, Full and Tweed power.
EL34 on outermost positions, 6L6 tubes on inner, same as above, all power modes, Class A, Simil-Class, Full and Tweed Power. Pentode /triode switch works just as good as the 6L6 quad.

The Mark IV can also be driven with 4 6V6, SimilClass only and Tweed power. (Read owner's manual for correct use).
The best word to describe the Mark IV with SED wing = C= : Wicked though a 412 cab. Hard to tell difference in a combo and single speaker. I should have tried out the 6CA7 and 6L6 setup in the Mark IV though the 412. I did not try it since I was focused on tone through the single speaker of the combo.

 

[swbo101]

The best word to describe the Mark IV with SED wing = C= : Wicked though a 412 cab.

+1

That is what I'm using now with a 6L6/EL34 combo. I just never tried 6CA7's before.

Thanks.

 

[bandit2013]

I decided to pull the JJ-6CA7 out of the Mark V, put the SED =C= back in just for kicks. I get in the habit of powering up both amps so I had to wait for the EH-EL34's to cool down, had to wait for the JJ-6CA7 to do the same so I played though the Mark IV for a bit to keep me entertained. Sure enough, I believe the SED are ready to retire, blame it on ear fatigue. I like the JJ-6CA7 much better (but that is comparing almost new tubes to close to tired tubes).

Swapped the EH-EL34 in the Mark IV for two of the JJ-6CA7. The center tubes remained unchanged which are Tung Sol 7581 (which are almost as retired as the SED's but sound great in the Mark IV). The 7581 would be the closest in tone to the SED6L6 when new. Great bass response and same top end, close in the harmonic content, just face it the SED 6L6GC is a hard bottle to break and hard to compare with other tubes. Two days ago I had a two of the SED with the EH-EL34 loaded up in the Mark IV combo (not bad at all). I am almost tempted to splurge on some more SED but too costly.... Back to the topic. If you think your Mark IV is dark (not as dark as a Mark III) expect to cut back on some mids and bass with the JJ-6CA7. I channeled the Mark IV thought the 412 and let it rip. Not bad, but I prefer the EH-EL34 with the 6L6. If you want mega bass, combine the JJ-6CA7 with TAD6L6GC. Now I am tempted to pull it off. The TAD6L6GC sounded better in the Mark V than the Mark IV for the same reason the EH-EL34 sounded better than the JJ-6CA7. I find the Mark IV runs on the dark side of the tone scale (more bass even when dialed out). The Mark V on the other hand is very bright especially with the SED 6L6 or TS 7581, and Svetlana copy. Still no reason not to try it. I found the bass to be too much with the JJ 6CA7 in use with the Mark IV. Same applied to the TAD6L6GC. On the other hand, running a quad of EH-EL34 in the Mark V sounded thin until you ramped up the master volume to the point too high. Perhaps the EH 6CA7 would make a difference in the Mark IV.

At least there are two choices for the time being offering 6CA7: Electro Harmonix and JJ. I will have to test drive the EH version. So far I have no issues with the JJ tubes. With the Mark IV, you can opt for the JJ-EL34L which has extended Bass. There is yet another sub for EL34, the power hungry KT77 (not sure if that is a suitable tube for Mark IV or V since it requires double the heater current )

 

[swbo101]

I find the Mark IV runs on the dark side of the tone scale (more bass even when dialed out). The Mark V on the other hand is very bright

I agree with that. So per your findings would you agree that with a Mark IV 'A' run with a 4x12 cab, a suitable replacement for =C= could be Tung Sol 7581 running in the middle sockets and EH-EL34 running on the outside?

What about a full quad of Tung Sol 7581?

I still have an unused quad of =C= 6L6s in my closet, but I'm always on the look out for a cheaper suitable replacement.

Thanks.

 

[bandit2013]

my Mark IV is a version B combo.

If you have wing = C= 6L6GC, use them when you need to replace your tubes. :mrgreen: I found them totally wicked in the Mark IV in lead channel and pumping through a 412. :shock: The SED's are hard to beat tone wise (will depend on the tubes and where they saturate in terms of early, mid or late distortion which would be relative to bias, not much you can do there.)

The Tung Sol is ok, the SED are far better. I found that the Tung Sol is similar as a quad as is the SED, in terms of low end and chime on top. I cannot tell the difference between TS, Svetlana, and SED when running though the combo amp speaker, but thought the 412, the SED tube blows them away. The is something about the way the SED tube saturates, almost similar to an EL34 overtone of harmonics but a bit different in the mids. I have tried the SED tubes with the EL34 but difficult to rate since the SED tubes are nearly worn out. The TS 7581 have not been used as much, they are probably at half life but they sound better than the Svetlana tubes that I bought to replace the Mesa STR420 (originals that came in the Mark IV, after 13 years it was time to replace them).

The TS 7581 is tight and complements the EL34. I decided to eat up the two mesa 6L6GC tubes that did not redplate in my Mark V and they sound really good with the EL34 tubes in the Mark IV. As it seems, the Mark IV is a bit more forgiving than the Mark V in therms of power tubes. I can easily tell the difference with the V than with the IV (especially when used as a combo amp).

 

[swbo101]

Thanks again for the insight, bandit.
Much appreciated.

 

[bandit2013]

No problem.

I currently have Mark V head driving an EV equipped 412, and a Mark IVb Combo with Fane speaker and an Emi Tonkerlite in a sealed extension cab. Sometimes I will use the 412 with the IV, but mainly the V is the primary for the 412. Sooner or later I will be adding a Royal Atlantic 100 to my small collection (still have not decided on speakers yet, not very fond of V30).

If both Marks were heads, my preference would be SED wing =c= 6L6GC for the Mark IV, JJ6CA7 for the Mark V. TAD6L6-STR are pretty good tubes for the V (not as abundant with the highs as the SED tube but a little soft on the low end). The TAD 6L6GC-STR are not bright tubes and if your amp is dark to start with, not the best option. For the Mark V with either JJ6CA7 or TAD6L6 best preamp tubes I found to be with the original Mesa 12ax7. Tried other preamp tubes to no avail, still sounded good but lacked the presence and high frequency bite. Also found the Mesa (or JJ if you prefer which are same tube) to run much quieter in V3, V4, V6 (AC heater) with longer plates you get more hum (v1, v2, v5 are dc heater circuits).

Tung Sol 7581 are good tubes for the Mark IV, similar in boldness to the SED and just as bright in the top end if not brighter. With the Mark V, expect to tube roll the preamp section to tune the amp to your liking. Current offering of Mesa 6L6GC STR440 sound really good in the Mark IV, too bright in the Mark V. The best all out preamp tube for the Mark IVb are the Tung Sol 12ax7. I have tried to roll preamp tubes in the Mark IV, just did not make a difference. The clean channel sound the best with TS in all preamp sockets. It does not seem to darken the overall tone of the mark IV. Perhaps there is not much in voltage shift between channels like as is the case with the Mark V. I will have to review schematics of the IV in more detail to confirm.

Svetlana also sound good in the Mark IV. The TS offers a bit more boldness.
What works good with EL34, Just about all of them except another EL34 tube or its variants (6CA7). The EL34 will sound a bit thin if you run the amp in Class A mode. I normally keep it in Simil-Class.

 

[swbo101]

That's good to know. Just as an FYI, what I've been using as pre-amp tubes for my Mark IV, which I like, are the following;

V1 - Tung-Sol (RI)
V2 - JJ
V3 - JJ
V4 - Stock Mesa
V5 - Mullard (RI)

The Tung-Sol is bright but clean for V1, the JJ's got the grit for the gain (also liked the Mullard there as well). I stick with the stock Mesa for the reverb driver and the Mullard is balanced enough for the PI slot.

 

[bandit2013]

I have found that the TS transfer characteristics to roll off on the highs a bit. However I would agree it is not as noticeable in the Mark IV. I bought enough 12ax7 TS tubes to completely fill the Mark V. The Mark V is definitely sensitive in terms of tone character of the preamp tube. The Mark IV on the other hand is more forgiving. I initially bought EH12ax7 for the Mark IV which are similar to the TS but higher gain. I pulled them to use in the Mark V and loaded the IV with the TS. After the preamp tubes had a few hundred hours of use on them in the Mark V, I began hearing AC hum from the heater circuits. It was mostly prone when operating CH3 which boosts the internal voltage to the driver tubes (the ones with the AC heater circuit). Found that the Mesa 12ax7A (same as the JJ tube) with shorter plate structure was very quiet (noise was tolerable). So now I have plenty of preamp tubes for the Mark IV to play with. Even the Mullards I got were noisy, one of them rattled and made it appear the power tubes were making the noise. Tap test found the weak ones.

You could almost put anything in the PI position and it will generally not add to the noise if it is noisy. My preference is the Sovetek LPS but when compared to the Mullard re-issue, it is identical. It is common to find tubes made by Reflektor (new Sensor distributor) to have identical tubes for different brands, and sometimes the cost may be different. However, what the eye cannot see may be different. Just for kicks, I tried both in the V1 socket of the Mark V and Mark IV, no difference in tone or character can be heard. The EH 12AX7 and the Tung Sol 12AX7 look identical too but they do not sound the same.

 

[bandit2013]

Considering the topic, what suitable alternates for SED =C= 6L6GC exist: Conclusion; The Svetlana Electron Devices with the logo =C=, originators of the Svetlana trade name, and manufactured in St. Petersburg Russia are by far the best 6L6GC tube in current production (assuming the rumors about "out of production" and/or "qualifying new materials" for improved quality which may be cause for price increase and lack of supply). Are there any subs that will perform as well? I have yet to find any. In my quest to find an alternate (that costs less than the inflated list price of the SED) the JJ6CA7 does a good job. It is, however, not the same in tonal characteristics. Performance of the JJ6CA7 in the Mark V amplifier is exceptional in CH1 and CH2. I actually like the tight bass and growl I get when the tubes break over into soft clip. CH3 (high gain channel) is where the difference between the EL34 type 6CA7 and the SED 6L6GC differ the most. The EL34 class tube (6CA7) will compress dramatically when using CH3. The only changes is the bias on the preamp tubes (operating point of the preamp section changes due to channel. Difference between CH1 and CH3 is 35V on the PI tube as well as other triode sections (exception would be V4A and V6B which remain constant). The compression is not bad per say, but there is a lack of detail that you would get from a 6L6GC. As of yesterday, I put the =C= 6L6GC quad back in the Mark V (bias switch is set once the tubes are removed so I do not have an oops with the 6L6GC tubes and loose a resistor or two). I would have to rate the SED =C= 6L6GC on the top of the list. I think I may just pay the extra cost for the SED's. May even get the =C= EL34 too. As for the Slovakian tubes (JJ) have the 6CA7, need to get KT77 (incorrect statement on heater current, confused with KT66), and JJ6L6GC. Was considering the tube kit for the Mark IV with the EL34L option (but since I cannot use them in the Mark V, I will stick with the standard EL34.

Last few words on the TAD6L6GC-STR, not bad (made in China?). Not at all harsh, but seems to lack the top end sparkle or bell tones that a 6L6GC should have. They do have a nice warm dry tone in the clean channel. I prefer the JJ6CA7 (EL34 class) tube over the TAD. On the other hand, it is much better than the Sovetek / Reflektor tubes (Saratov, makes EH, Svetlana (copy, but same tube as the EH or TS), Sovtek, reissues of Tung Sol, Mullard, Genalex, and probably others). The Reflektor tubes are okay, they seem a bit harsh / brittle on the top end.

I have not tried NOS tubes older than the 90's (my current SED are relabeled SED 6L6GC by Groove Tubes, Gold Series GT6L6R-2). So far they have held up to the hotter bias of the Mark V. Can't say much for the Mesa STR440 6L6 since they were toast within 2 months of ownership of the Mark V. The TS7581 were the replacements, but they went flat in about the same time frame as the Mesa tubes redplated. (mostly due to a dying 5U4GB rectifier). After replacing the rec, they sound better. I tried them in the Mark IV and they sound great (provided more punch in the low frequencies). I got the Svetlana tubes for the Mark IV originally. Not sure what to expect, but they are similar to the TS7581. They sound okay in the Mark amps, but they are by no means SED =C= 6L6GC tubes.

 

[bandit2013]

With power tubes, it is not only your preference in tone that matters, but how it sounds in your amp that may the perfect match or complete dud.

What works well in the Mark V sounds terrible in the Mark IV. I have tried a pair of the jj6CA7 in the Mark IV, they do not blend well with any of the 6L6GC tubes I have available. Worse tone achieved was with the JJ6CA7 and the TAD6L6GC-STR. Not only did the clean channel sound weak, everything else was muddy! So far the EH EL34 sound great in the Mark IV, completely too thin for the Mark V. The jj6CA7 sound absolutely terrific in the Mark V (probably because the bias on the Mark V is on the hot side compared to the Mark IV ? ). The same applies to the Tung Sol 7581 and Svetlana tubes. They sounded very harsh in the Mark V, but nice in the Mark IV. If you look at the Eurotubes web site, they do not offer the 6CA7 in the retube kit for the Mark IV. I looked at the Mark III kits as well. Not recommended to use the 6CA7 ? Perhaps the EL34L would be a better option. (I probably will not try the EL34L since it cannot be used in the Mark V. That may change once I get my hands on the RA100).

I did like the combination of the EH EL34 with the TAD6L6GC-STR. Nice and crisp tones in the clean channel, slightly deeper than the Tung Sol 7581 when paired up with EL34. Lead voice is really good with the TAD6L6GC and EL34. That is a good combination I think I will leave in the Mark IV for a while. I did previously try the full quad of TAD6L6GC-STR in the Mark IV and I was not impressed with them. As a quad, they are better suited in the Mark V. However, I feel the TAD6L6GC-STR sounds better as an integrated quad when paired up with the EH-EL34. Definitely an improvement over the Tung Sol 7581 (not as tight in the bottom and sharp in the top end). Tung Sol 7581 would probably best used for Chugging if that is all you do. IF you want a killer set of quads for the Mark IV (412 or more) the SED =C= 6L6GC is worth it (hard to tell the difference if you only have a combo, I have both combo and 412 at my disposal).

 

[shimmilou]

Information overload......must compute......error........error....e..rrrror....eeer.....rrrror.... <beam into space.....explode!>

:lol: