Blue Angel club

[Natman]

Hi all,

I just bought a 112 Blue Angel after some effort and am ready to start modding. Alright, I don't have the amp yet (it's in transit) but I'm a hopeless tinkerer and want to get the most out of the thing. I'll start by trying different speakers, pop some 12AT7's and NOS in. I read something about a mojo module?? Does the rectifier tube make much difference? I read something about the load when using just 6V6 or just EL84's. If the tubes are class A, does that mean I don't need to buy matched sets?

Do you have suggestions on good speakers? (I'll stay with 1x12 for now) I have a couple on hand that can handle 38W: WGS Blackhawk HP, Mojo Greyhound (Could a Mojo BV30H handle the power?).

I'm just doing my homework like I always do. All advice is welcome. Thanks in advance!

 

[94Tremoverb]

Try your 12AT7s in V3 (reverb) and V5 (phase inverter) and possibly V2. A 12AY7 is better in V2 though. NOS throughout is definitely the way to go! I liked RCAs and GEs in the preamp mostly.

You need matched sets of power tubes. The amp is cathode-biased (not actually true Class A, despite the front panel) so it can take any 6V6s and EL84s, but common-biased rather than individually-biased so you still need matched sets. The rectifier tube does make a difference, but obviously more as the amp is cranked up, and much more in the Simul and EL84 modes than in the 6V6 mode. I liked Brimar CV511s (British military 6V6s) and GE 6BQ5s best, for the most contrast between the warm 6V6 tone and the snappy EL84 tone. I prefered a 5V4 rectifier to the stock 5AR4, it had a little more sag and sweetness.

For maximum headroom and clarity in the 6V6 mode, plug the 8-ohm speaker into the 4-ohm jack which is a better match. But, you may find you prefer the softer overdriven tone with it still in the 8-ohm jack (which is presumably why it was designed like that), it contrasts more with the crunchier EL84 tone.

If you want to get more experimental the 6V6 sockets will run safely with 6L6s (which also removes the mismatch in the '6V6' mode but means the Simul mode really wants the 8-ohm speaker connected to the 16-ohm jack) - I tried some small-bottle Philips 6L6WGBs which sounded nice, as well as a pair of ancient original Tung-Sol 5881s which were badly mismatched but sounded great, apart from a bit of hum. If you want to get seriously adventurous it appears to be safe to run it with just *one* 6L6 (though not one 6V6!) as a single-ended amp... but I can't 100% guarantee that.

The Mojo Module is an internal part that can't be removed - it's actually equivalent to a turned-off Mark Series graphic EQ, and drives the FX loop as well.

I don't have any experience with the speakers you mentioned, sorry. Mine sounded best with a Celestion Alnico Gold in it, but I would hope so at that price .

Hope that helps! And none of that involves actually opening the amp up, even. If you do, take heed of the warning about the preamp remaining live even with the standby switch on - the reason it's a Dual Rectifier is that there are two, tube for the power amp and solid-state for the preamp, which is not turned off by the switch. This is to make sure the preamp has more headroom than the power stage, so the distortion is pure power tube - one of the few amps that is.

 

[Natman]

Now that's what I'm talking about! Great pointers -thanks man! Will report as I go (and probably pester folks for advice).

 

[94Tremoverb]

Writing all that made me miss mine . I sold it to a good friend because he was keen for one and I wasn't really using it enough to justify keeping it. Possibly a mistake...

 

[Natman]

I read on TGP that the BA has a lot of negative feedback. I imagine this would allow for safer mismatch of the speaker/output impedance?

I also read something about a revision to the circuit by Mesa Boogie at some point. Any idea what that entailed? (I lost the link to that discussion)

 

[94Tremoverb]

Not sure how much difference the negative feedback makes to the impedance sensitivity - probably not much. In fact, from what I remember none of the ratios are that accurate anyway - nor can they be, if you're going to use two different power tube sets with different inherent impedances... even separately, let alone together! Don't worry about it - it's useful to know which matches are closer than others because it helps predict the tones, but it probably doesn't matter from an amp safety point of view unless you do something really daft like running a 4-ohm load from the 16-ohm jack with the 6V6s... and even then you'll most likely just shorten the tube life. Mesas are very tough and can handle that kind of abuse.

The earliest ones had a switch to let you use the solid-state rectifier on the power stage as well. I tried it, just to see - it sounded less sweet, and not in a way I would think would be useful - just harsher without really being tighter or crunchier. I can see why Mesa deleted the option. I don't know if there were any other revisions or not, sorry.

 

[Monsta-Tone]

I've had 2. A 1x12 that I loved and a 2x10 that was just ok.
The 1x12 had a horrible hiss in the Mojo Module. I bypassed it and the hiss magically went away! But...so did the FX Loop since the Module drives the Send.


Great amps! Great info too 94 Tremoverb!