IIC+ Goldilocks Circuit

[WaxCapacitor]

Been scouring this thread for a couple years now and decided to join….

Recently sold a iic+ SRGX , and have pulled my HX out of storage to dial similar tones ….

Off the bat the HX has a “fizzier” and somewhat “duller” saturation on LEAD channel… whereas the SRGX had a more dynamic, raw , inspired saturation that I got used to. To me it boiled down to the pick attack, and resulting “feel”. I was able to dig in naturally and for all intents and purposes it was the best sounding iiC+ I’ve heard.

It was a SRGX iiC+ combo , that I switched out the EV12L for a ms-12. To be honest I wouldn’t mind if all ev12L’s were thrown off a bridge never to be found again. To me the completely neuter a iiC+ or iii .

I’m wondering if this phenomenon I’ve heard about recently of the filter cap values drifting over time from say 25uf to 10uf , or 5 uf. I’ve heard that as long as the dielectric is intact and the voltage capacity is still there, that a drifted filter cap can work fine.

I also wonder if the models with reverb may behave differently. If you’ve got a signal off V1A , routed to reverb driver and recovery , you are bypassing the tone stack and blending the 1st gain stage with the raw guitar sound. I would put verb on 1 , maybe 2 to blend signal with tone stack this way and also get a subtle spatial effect.

This was the best tone I got out of the iiC+ , as the lead channel and amp in general can be a little too dry for my tastes.

Lastly , the SRGX had original STR-15’s and OG 12ax7’s . I’ve scanned around and some say the difference is marginal between OG tubes and JJ’s (as an arbitrary example). I’m not sure I would concur. The STR-15’s had a focus and urgency that I don’t hear with other tubes . Right now I’ve got El Menco 6L6’s loaded in the HX , El Menco 12ax7 in V1- Amprex ax7 V2 - Amprex 7025 V3, and El Menco 7025 in phase inverter. Maybe overkill for 7025 in V3 ?

HX isn’t terrible , but definitely not yet inspired by it . I’ll throw new filter caps in to see if it opens the tone up, and probably stuff the HX chassis in a Mark iii cab (with ms-12).

After that , I can’t think of anything other than the happenstance of resistor/electrolytic values drifting from their original spec , into somewhat of a Goldilocks situation , or the STR-15’s are really just that bold.

Anyone notice this with a HX , SX, H, or S ?

****Im running a mesa 5 band in the FX loop of HX **** ….and I’m convinced it behaves exactly the same as a built in GEQ (Mike B endorses that observation as well) , so that isn’t of concern for the natural of my post …..

Thanks , sorry for long winded post

 

[Joey1970]

The Sylvanias are really that bold. STR-415 or STR 415/416 in my DRG Mark 2C+ amps, for sure. One set up for the high gain blend, 2nd one with all 415 for the crazy clean, the 3rd one on Class-A with only the 416 in Class-A 15 watt mode. All with the EVL-12L speakers.

 

[WaxCapacitor]

Makes sense! Yeah there was an “excitement” factor in the highs, like a note bloom specific to transient fq’s . The low end also created a foundation, and like another user described (w/ ms-12 speaker) mid’s were rich and “smeared”.

Do you have an STR-15’s for sale? Is there a Sylvania model tube that would work ?

You think Mesa / Sylvania 12AX7’s have any bearing on the sound ?

 

[Jay Omega]

Makes sense! Yeah there was an “excitement” factor in the highs, like a note bloom specific to transient fq’s . The low end also created a foundation, and like another user described (w/ ms-12 speaker) mid’s were rich and “smeared”.

Do you have an STR-15’s for sale? Is there a Sylvania model tube that would work ?

You think Mesa / Sylvania 12AX7’s have any bearing on the sound ?

My opinion is that power tube differences in a mark-style are overstated. Maybe some differences, but minor enough as the mark has a lot of controls to tweak the sound to compensate

 

[bandit2013]

I do not have a vintage iconic amp like you have. My Mark III was so equipped with the STR415 and STR416 as original power tubes. I no longer have that amp in my collection. I do have a more modern take on a IIC+ HRG in the form of the Mesa JP2C. I have tried different preamp tubes and not much seemed to change. The old 6N4-J Beijing tubes that were originals in my Mark III made the JP2C extremely fizzy sounding. I recently purchased a quad of NOS Mesa STR415 direct from Mesa. They may still have some in their hidden inventory. You would have to send an email to Mesa Customer service to get the work order rolling. If anyone responds from Nashville (or was that Memphis?) they have no clue and will claim they do not exist. Kris Dilbeck through customer service should be able to set you up for the STR415 if they are still available. You may need to address him directly. Most of Mesa's customer service is handled by Gibson so calling in will be a waste of time as it usually goes to Gibson and not to Mesa Boogie. I got my set of STR415 this past July.

The blue ink will rub off with handling. After getting them out of the box, the ink is no longer on the tubes. They are that old. Took a day or two of use for them to bloom into what I hoped for or anticipated they would sound like. There is no substitute for them.

Since you have the X version, (sorry for my lack of education on this subject), I would assume that runs a plate voltage of around 510VDC? The STR415 is the only way to go. It will cost about $510, depends on taxes and shipping fees. If it is not up that high in voltage, say a bit lower at 480VDC to 490VDC the STR448 in a green or gray bias color rating would work out. I have also run those in my JP2C, it had more of an airy sound compared to the STR415 but they also did the business end of the grind quite well. As for the STR448, I would avoid the red or yellow or blue bias colors.

As for the preamp tubes, thought the originals back in that era were Tungsram 12AX7. I should get some and see how much different the JP2C would sound. Probably not the same as the real deal though.