Mark V, Jensen Blackbird recordings

[bandit2013]

The most important thing about this speaker is to have patience during the break-in period. However, I did not practice what I preach and was a bit impatient. Most of the issues I experienced may be at the extreme, tube failures, tube vibrations, faulty power tube (cutting out) and so on. Some common issues will have a familiar sound to them with ceramic speakers, when it comes to ALNICO, such issues will not sound familiar and easy to assume the speaker is at fault. Also I had a not so pleasant experience with a WGS BlackHawk HP100 that did not survive the break-in period after installation to a Mark IVB combo. I may have been a bit cautious or naïve at the same time. I will have to admit that the character I crave about the RA100 and Roadster amps is the pick attack, sensitivity and response which makes the amp and your guitar come alive. I was not willing to give up on my Mark V. I do realize this amp has potential. Unfortunately I have not been able to enjoy the amp much through the MC90 speaker as the cone had some defects and such. Note that the combo shell was purchased used and it came with the speaker already installed. The speaker stayed in storage most of the time as I preferred (I thought) an EVM12L. Something about the EV, it is bold, dark and very bright all at the same time. What is hard to notice is the essence of character you get from the amp and speaker combination (Mojo if it were) unless you had a reference point to compare too. I always wanted to try the Jensen Blackbird from the Jet series. 100W ALNICO 12 inch speaker with a 2" voice coil. I had a few hang ups but not speaker related. Just a note: Alnico speakers will make some odd sounds during the break-in period, also need to reserve higher volume playing until at least 10 hours or more to prevent overheating of the voice coil as it is working against the compliance of the speaker suspension. After a few hours, the tone will change as the mid range frequencies begin to blossom. I doubt the speaker has reached its sweet point, but it does sound really good now in the Mark V that is deserving of recording it.

For the Clean channel recording: I used the Fat Clean, 90W and no EQ. See image of settings if this interests you below the sound file link.

https://soundcloud.com/user-353100000/mkv-jbb-cleanwav

Crunch Time: CH2 Crunch, 90W, EQ active.

https://soundcloud.com/user-353100000/mkv-jbb-crunchwav

CH3 Mark IV mode, Pentode setting, 90W, Classic V EQ.

https://soundcloud.com/user-353100000/mkv-jbb-mkivwav

 

[bandit2013]

Forgot a picture that I intended add to the beginning of the first message.

Tubes used in the Mark V for the Recodings: Preamp: All Mesa 12ax7A tubes. Power AMP: EH 5U4GB, Ruby 6L6GC-MSTR

 

[bandit2013]

After restoring the bias voltage to its specified value (well close enough anyway) I am not sure if I preferred the additional headroom with the modified circuit prior to restoration. Near stock brings the life back to the bottom end and sounds more like it should. Having the 100k resistor in series provided more headroom but less bass (bias voltage -52.3V. It actually sounded vintage but not exactly what I wanted. I did removed the clipped leg and rest of the stock resistor and replaced it with one that was 20k larger in value (military grade high precision 0.1% 1/2W resistor) brought the tone back to normal. Change in bias voltage -51.44V vs -51V. No need to worry on the effects in 10W power mode as the bias voltage circuit is not used (power tube circuit changes to a cathode bias topography, those gold anodized power resistors mounted to the chassis are the cathode resistors. The more I study the Simul-class power scheme the more I admire it. Perhaps having an adjustable bias pot would make sense to tune for plate current of the center pair of tubes, I prefer the fixed bias actually and have not had any issue obtaining tubes of different makes to work in the amp as specified. I just have not had any luck with the Mesa branded power tubes in this amp in particular. I absolutely love the Mesa 6L6GC in the Roadster but that has a different power amp topography than the Simul-class. I should probably re-do the recordings now that the MkV is back to its tonal character.