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 Post subject: Help with tubes Roadster
PostPosted: Sat Jul 12, 2014 9:48 am 
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Mark I

Joined: Wed Oct 23, 2013 3:52 pm
Posts: 24
Hello. I plan to retube my Roadster. I saw some retube sets on http://www.rototubes.com/Roadster-Trem-O-Verb/
I know that Roadster have fixed bias and they recomend Mesa tubes for Mesa amps. Do i need any additional moding or i can just install some of this sets and go play.


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PostPosted: Sun Jul 13, 2014 10:48 am 
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Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2151
Location: North Carolina
From what I learned thus far with the Roadster.

V3 (tone stack triode) V5 (FX loop send) are cathode follower circuits. Either use Mesa (selected JJ tubes) or Chinese (have nickel plated clips on the plates). Russian made tubes will fail prematurely in the Cathode Follower circuits due to the voltage differential between the heater and cathode. An alternate is the JAN/GE 5751 which is supposed to be compliant with cathode follower circuits.

Somehow I believe that Mesa also selects their preamp tubes for matched triodes, otherwise there would be an out of balance signal to the power section (matched triodes are better served with Class A/B power amps, it probably does not matter much with the Simul Class circuits of the Mark Series amps but it does not hurt to used matched triode tubes there either).

I honestly prefer the Mesa tubes in the Roadster. I love the way the Mesa power tubes sound in this amp when saturated. They come close to the SED=C=6L6GC that I have used in the Mark V. I have experimented with EH EL34, TAD6L6GC STR, SED =C=, and KT77 (all of which I specifically ordered for my Mark V ) The TAD6L6GC-STR sounded great as well as the EH34's. I have not tried the newer set of SED =C= 6L6GC or the EL34 (in use with my RA100). I prefer the tone of the Ruby (Mesa Branded STR440 in the Roadster). Since I am not using the SED =C= 6L6GC at the moment (loaded the KT77 in the Mark V) I should give them a shot in the Roadster. I have also tried some of the different preamp tubes (EH, Tung Sol, Mullard reissue, Mullard CV4004, Preferred series 7025, and vintage Mesa Chinese tubes (which I think sound the best overall in my other amps). The Roadster seems to benefit tone wise with the Mesa branded JJ 12ax7a tubes. I did not notice much difference in gain structure, but I did notice more brightness with the Mullard reissue and a Sovtek LPS in V6. However, it became apparent that the tone I liked with the stock tubes was not the same with the different preamp tubes. My experience with the Mark V is quite the opposite, I did not like the Mesa JJ tubes, actually it is a fault with the power section as I believe it is running a much hotter bias than it should ( I have red plated many of the commonly bought tubes except for SED or Gold Lion KT77 ( I ordered them specifically for a fixed hot bias amp and so far no issues). Roadster and rest of the DR family, they run on the cold side as I recall.

The weak link is the rectifier tubes, not many available. I did try a NOS JAN 5U4G but it was a dud. I normally use either Mesa or EH 5U4G (same tube). I believe the Roadster would sound great with many of the 6L6GC tubes available since it has a moderate bias and does not run as hot as the Mark V.

If you were considering a different tube than a standard EL34, 6CA7 had some interesting character too them. (I would avoid the JJ 6CA7, many have had great success with the EH 6CA7). Also you can run the EL34B (lower bass response). As far as EL34 are concerned, the SED =C= EL34 are tops but much higher cost. Gold Lion KT77 are also a big expense. I like the EL34 (SED) the best.

The Svetlana (not true SED or Sevetlana from St Petersburg) are not too bad either (made by Reflektor, also makes Tung Sol, Sovtek, Mullard, etc...) I have been running them in my Mark IV for the past 2 years. Close but not close enough to the SED =C= tube. Tung Sol 7581 are also killer tubes (has more complex harmonics than the Svetlana). I have a quad of those, wonder what they would sound like in the Roadster ?

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Current amps:
TC-50, JP-2C, MK V, Roadster, RA100
Old friends I sometimes miss:
Mk III (blue stripe), Mark IVb-WB


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PostPosted: Wed Jul 16, 2014 9:20 am 
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Mark I

Joined: Wed Oct 23, 2013 3:52 pm
Posts: 24
Thank you for your reply. It was very helpfull for choosing type of tubes for me. My concern is can i put any tubes not only Mesa branded in my Roadster and just use it or non mesa tubes need some kind of biasing or moding the amp.


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PostPosted: Fri Jul 18, 2014 6:04 am 
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Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2151
Location: North Carolina
If your amp is under warranty, best to use Mesa tubes. I have experimented with some of the preamp tubes and power tubes just briefly so I could compare the effect on tone. Tung Sol in V1 will tend to brighten up the amp as well as a Mullard Reissue. I did not care for the change in tone. Unfortunately, most of the power tubes I have available were ordered specifically for the Mark V so they were not as defined in the Roadster or RA100.

If you are not concerned about warranty and are really eager to experiment with different tubes, the Roadster is more forgiving than the Mark V due to a cooler bias. Typical power tubes will work well. When you order tubes, some places allow you to specify what tubes the amp will be installed in, and if it is a combo or not. Groove tubes with gain factor ranging from 4 to 7 are acceptable. The lower the number the earlier the distortion would be. Some tubes vendors rate them in terms of low, medium or high distortion levels, stay in the middle range and indicate your amp make and model. Not sure if specifying a Combo will make much of a difference but I assume they will be more stable in the mechanical aspects (less vibration of the internals). I think the next time I order tubes I will indicate a combo amp. I have gotten some noisy tubes in the past, vibrations were not noticeable at higher volume but at low volume the tubes sing (vibrate and rattle, this is more prone for EL34 and associated narrow bottle tubes that are similar )

There are tubes that hold up better than others. TAD are not bad at all, SED expensive but hold up well, Gold Lion are good but cost more than the SED tubes. Some of the Reflektor branded tubes (Tung Sol, EH, Sovtek, Mullards, and Svetlana) are also good. It can be hit or miss when it comes to tubes and quality. Generally using a source that selects tubes and sorts them for quality of sound and mechanical stability (Mesa and Groove Tubes). Also finding a good source for a good matched duet or quad. I generally use "the Tube Store" or "tube Depot" for the other brands of tubes. Just my opinion and I will restate it, I found the Mesa tubes to have the best overall sound quality in the Roadster. The Complex harmonics are present when saturated in CH3 and CH4. So my Roadster will only get Mesa tubes. As for preamp tubes, I believe the Mesa 12ax7 are match triodes. If you decide to use other brands, it should be required to get a matched triode for the PI tube (V6). Having all of the preamp tubes with matched triodes would not hurt (except your pocket book). You could probably use most common tubes available for V1, V2, V4, V6. However Russian tubes will fail in V3 and V5 due to cathode follower circuits (JJ or Chinese Shuguang {with additional chrome like clips on the plates}). If you get a bad tube and something happens to the amp, your warranty will not cover you unless it is a Mesa tube (not sure about GT).

You do not need to modify anything in the amp at all. No bias change needed as long as you stay in the mid range. Always good if the resource you are using will match the tube for the amp requirements based on its bias data they keep on hand.

A reminder on the Rectifier tubes, stick with the exact same type tube. 5U4GB. Mesa or EH have these available.

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Current amps:
TC-50, JP-2C, MK V, Roadster, RA100
Old friends I sometimes miss:
Mk III (blue stripe), Mark IVb-WB


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PostPosted: Thu Jan 12, 2017 4:00 pm 
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Single Recto

Joined: Mon Mar 09, 2009 5:16 am
Posts: 1258
I really love the Winged C 6L6s in my Roadster head and Mark V head. I feel they are a slight upgrade over the stock 6L6s. However, as we all know, they have stopped making the Winged Cs. So the quest to to find a similar replacement for me


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PostPosted: Sun Jan 15, 2017 8:23 pm 
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Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2151
Location: North Carolina
I have been searching quite a while for a suitable replacement for the =c= 6L6GC. What does come close is the Tung Sol 7581A (at least for the Mark V).
TAD 6L6GC-STR are a bit different but sound great. I actually liked those more in the Mark V than the SED =C= 6L6GC. What I did not like about them was the plastic base, the center guide pin can break off easily. If you get them, use a silver Sharpie to mark where the key on the center pin is on the side of the plastic base. Forget about the Svetlana tubes as those will not last long in the Mark V. For the Roadster no issue as the bias is not the same.

_________________
Current amps:
TC-50, JP-2C, MK V, Roadster, RA100
Old friends I sometimes miss:
Mk III (blue stripe), Mark IVb-WB


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PostPosted: Sun Jan 15, 2017 8:54 pm 
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Single Recto

Joined: Mon Mar 09, 2009 5:16 am
Posts: 1258
bandit2013 wrote:
I have been searching quite a while for a suitable replacement for the =c= 6L6GC. What does come close is the Tung Sol 7581A (at least for the Mark V).
TAD 6L6GC-STR are a bit different but sound great. I actually liked those more in the Mark V than the SED =C= 6L6GC. What I did not like about them was the plastic base, the center guide pin can break off easily. If you get them, use a silver Sharpie to mark where the key on the center pin is on the side of the plastic base. Forget about the Svetlana tubes as those will not last long in the Mark V. For the Roadster no issue as the bias is not the same.


I would have thought the longevity issue was due to the fact that it's enclosed in a smaller head cabinet, as opposed to be a bigger one which may help ventilation


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PostPosted: Thu Jun 29, 2017 5:33 pm 
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Bottle Rocket
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Joined: Fri Oct 21, 2016 5:02 pm
Posts: 13
Location: NYC
[quote="bandit2013"]

Just my opinion and I will restate it, I found the Mesa tubes to have the best overall sound quality in the Roadster. The Complex harmonics are present when saturated in CH3 and CH4. So my Roadster will only get Mesa tubes.

Hey Bandit2013,

You seem to know a lot when it comes to tubes and the Roadster. I recently blew a one of my power tubes in my Roadster. You say you only use the Mesa branded power tubes because you think they sound the best. I really love the sound of the amp and don't want to change anything but at the same time if there is a tube that would be better suit what music I play I'm open to using a different tube. I mostly play Metal and Progressive Metal. I love Metallica, Dream Theater, 80's metal as well as guitarist like Steve Vai and Joe Satriani. I was going to take your advice and just get a matched pair of the 6L6 STR 440's but if you have any thoughts otherwise I would greatly appreciate it.


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PostPosted: Thu Jun 29, 2017 5:47 pm 
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Mark II

Joined: Wed Aug 04, 2010 10:32 am
Posts: 83
Location: New Jersey, USA
I would think that replacing your power tubes with the same type would be best, unless you can find a compelling reason to change it up. They also really are the tubes the amp was designed around.

EL34s will give you more of a crunchy mid, high mid sound, and a tighter, less rounded bass response.

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Guitars: Hamers, Heritages, G&L Legacies, EBMM Steve Morse, Carvin Bolt, Fender Tele
Amps: DC-5 1x12 w/Master Volume + EFX Mods, Maverick 2x12


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PostPosted: Thu Jun 29, 2017 6:57 pm 
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Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2151
Location: North Carolina
Sorry for not noticing this....
Thing to take into account is the plate voltage of the amp. Not all Mesa's are operating at the same plate voltage and thus each model will have a specific bias for the plate voltage. Not exactly sure where the roadster stacks up with the Mark series amps or others in that regard. Depends on the power tube arrangement if it is a full Class A/B (all Rectifier amps I believe are this, not sure on the one's that use the EL84) Some Mark amps use the Simul-Class circuit and a select few run the full Class A/B. Each will have its on character.

I would suggest if you were to venture outside of the norm and select tubes that are different, indicate to the vendor what amp they will be used in so they can at least select a tube that will perform best when they are performance matched. The Ruby MSTR which are the same as the Mesa STR440 do have a slight different tone to them. May be due to the selectin process. I actually like them just as much if not a bit more but it depends on what amp I have them in. However, once you change V1 in your amp (Roadster is almost a necessity to do so) the bottom end and lower mid gain character of the Mesa tubes is a bit reduced. There may not be much to change in terms of tubes that the Roadster will respond well due to the cathode follower driven tone stack.

Only time I really noticed much of a change was using a JAN/GE 5751 in V2 (this tube does not share both triodes with all channels one half is used for the CH1 and CH2 and the other CH3 and CH4. V1 needs to have a good gain characteristic as well as V2 but the frequency response of the tubes will matter. Tube rolling has not been as much fun in the Roadster as it is in the Mark V. Other than the usual Tung Sol in V1, there is not much out there to experiment with due to the cathode follower V3 that drives the tone stack late. Not much else I can think of on the Roadster... How to get there from where you are at is or may be difficult. In short you have options for V1 and V2 for tone and character shaping and that is basically it except for the PI tube V6 and of course the power tubes. Power tubes with an early distortion characteristic may not be as desirable as you may think. I typically find that less is better than more, you can only distort the signal so much before it becomes mud. I would prefer a bit of mud verses brittle ice pick.

There may be some power tubes that would be killer. Tung Sol 7581 sounded great but I had already spent most of the tube life in the Mark V before trying them. I have read somewhere in the forums on the Mesa 5881 tubes. I have not tried them so hard to relate how they would sound in the Roadster. The SED =c= were kick ass tubes but harder to get those now. Also a quad of 6CA7 would be interesting to hear, I need to get a set to find out. My try the EHX version as I had the JJ versions and they were incredible in the Mark V but crapped out in too short of time (2 seeks, lost one tube due to open circuit issue internal that was intermittent ). Some do like the JJ EL34L as well.

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Current amps:
TC-50, JP-2C, MK V, Roadster, RA100
Old friends I sometimes miss:
Mk III (blue stripe), Mark IVb-WB


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PostPosted: Tue Jul 25, 2017 1:08 pm 
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Bottle Rocket
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Joined: Fri Oct 21, 2016 5:02 pm
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Location: NYC
Bandit2013,

Thanks for the info about my tube options. Looks like I have a little research to do before I get some new tubes. In the meantime I decided to use some tubes from my Road king and may have messed something up. While I was waiting to get some new tubes I pulled the 4 6L6's from my much newer Road king II. The Roadster sounded so good with the newer tubes I decided to swap the 6 12AX7's as well. I follow the tube charts in the manuals but when I powered up my Roadster things sounded really bad. Channel 1 sounded fine but when I switched to channel 4 it had no gain. It sounded like an overdrive pedal. Then when I switched it back to channel 1 there was barely any volume at all. So I decided to swap back the original 6 12AX7's but there was no change. I double checked to make sure the tubes were seated properly. I really don't understand what I could have done. Any thoughts how to correct this would be greatly appreciated.


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PostPosted: Tue Jul 25, 2017 7:00 pm 
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Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2151
Location: North Carolina
The Road King II has the same tube assignment as the Roadster. Not sure what would be causing the lack of gain or other issue. Typically if it only effects CH4 and CH3, it may be V3 but it can be V2 as that tube circuit is where the signal splits for the high gain channels and the low gain channels. Also check your FX send level in case you moved it to a negative setting if you are using the FX loop and master volume control. That gets me every time.

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Current amps:
TC-50, JP-2C, MK V, Roadster, RA100
Old friends I sometimes miss:
Mk III (blue stripe), Mark IVb-WB


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