Vox ac30HW and Tony Bruno

[cap217]

Tony Bruno helped design or redesing the HW amps that are out now. It seems like most reviews are good but I read that Brad Paisley had Bruno mod his new ac30. I dont know what he did but he said it had to do with something that they couldnt do during production. I assume due to cost. Anyone know what he did/does?

Also know that Psionic does some easy mods listed here:

http://www.psionicaudio.net/services/se ... mp_mod.htm

I ask because I just bought an ac30 and am getting these mods done. What is the difference in stock vs these mods? Anything stand out?

[Mark]

I can't say I've heard a Tony Bruno amp that impressed me. I think the issues I have with new AC-30's is the transformers sets they use.

[Turbojunkie]

Same here on the Bruno stuff, when I worked at a guitar store we had a few come through, and never got into 'em. That was 15 years ago though, haven't heard recent Bruno models, and I do think the newer HW AC30's are respectable out of the box...I think you're on the right track, lots of people rave about them after doing some mods & especially transformer swaps. Like Mark mentioned, the stock trannys seem to hold them back from what I'm reading and hearing from others, that is the main corner they cut in production. Good luck, really hope it works out for you! I'm turning into an official Vox/EL84 nut!

TurboJunkie

[cap217]

So the mods that pinsonic does are good? I didnt get the xformer swap but I am thinking that I might need to after the 2 replies.

So what xformer? Pisonic says that only the OT is needed to swap. He says that the choke and PT dont make that much of a difference. He recommends MM but I am sure there are better/other cheaper choices.


I have also heard that I should be using ecc80's instead of 83's. What do yo think about that?

[dave g]

For an AC30 or any 4xEL84 push pull output section I don't think you can do better than a Dynaco A470 (or a replica):

http://www.triodestore.com/noname.html

[cap217]

For an AC30 or any 4xEL84 push pull output section I don't think you can do better than a Dynaco A470 (or a replica):

http://www.triodestore.com/noname.html

I read a lot about this A470 and people seem to like it. I guess this vs the classic tone or the MM is my best option. I am going to give the stock OT a chance though. I can always upgrade.

Is the ClassicTone ultralinear? It has to be but I ask because the MM says ULTRALINER and the 470 says ULTRALINEAR. Someone also sent me a PM that said "I went with the MM over the classic tone because I needed it to be ultralinear". This got me thinking...

[dave g]

Huh? I don't use the ultralinear taps, I just cap them off. I have never heard an ultralinear guitar amp I liked. I also don't like MM at all.

I'm full of opinions

[cap217]

Found this on gearslutz, its helpful for my question:

ultralinear - UL taps to the screens (strong clean sound, not so graceful breakup, a bit crunchy but not bad)

Pentode mode - screens connected to b+ using a series resistor between 470-2.2k (a bit more power than UL with similar breakup, perhaps a bit dirtier breakup)

triode mode - connect the plates and screens together. use this only if the b+ is 400V or below as modern tubes can't handle such voltages (rounder sounding clean and smoother breakup, also subsantially less power)

To switch between all three modes you need more elaborate switching. As to the hum issue, make sure the input signal (from the jack to the first preamp tube) is as short as possible. Use a shielded wire for all low level signals, always grounding only one end of the shield. Keep the b+ perpendicular to and as far away as possible from any low level signal wires. Move the first preamp stages to the opposite end of the power supply/power transformer. Snubbers in the rectifier help a bit, as well as using hexfred diodes. Make sure there are no ground loops. Use either star grounding or a heavy gauge copper bar along the chassis. Use a metal cover on the chassis to keep RFI at bay (ever heard a radio station through a cranked amp?, lol).

I you need reference Pentode circuits check out my website, there some Fender and Marshall schematics there. For a ultralinear schematic look here http://www.schematicheaven.com/fende...-bmstr_rev.pdf

For triode simply connect the plates and screens together (make sure the voltage is low)

Ultralinear mode is not very common for guitar amplifiers, although some good soundings amp use it (including mine, lol). In ultralinear mode the tube produces a little less power than pentode and the transfer curves look different (the tube behaves differently). Look at the tube charts on my website, Welcome To Vacuum Tube Central® UL introduces more feedback to the output stage so it it doesn't sound as round as triode or pentode. One common trick is to use less global feedback in UL to get a softer sound. Also, if you are looking for a more vintage sound you can use a tube rectifier in the gz family, these tend to have more sag than the later types (5U4?). Tube rectifiers will need lower capacitance in the power supply caps (30-40 microFarads) than diode rectifiers.

[Masco]

No AC-30 MM OT is ultraliner. Just looked at their current prices for the public, $265 for a Woden clone!!!!!!!!!!

MC has a nice AC-30 OT. Have yet to try the A470.

[Masco]

No AC-30 MM OT is ultraliner. Just looked at their current prices for the public, $265 for a Woden clone!!!!!!!!!!

MC has a nice AC-30 OT. Have yet to try the A470.

[Turbojunkie]

Yes, MM's prices are nuts, but I have to say that I really like their version of the Woden OT...I'll be trying the Pacific A470 clone OT that I have soon, not going to be running it ultralinear...

I really want to try a Woden clone from Chris Merren at some point.

Masco,
Are you the guy that builds the JMJ-30's that everyone raves about?

Will report back on the MM Woden/Pacific A470 OT comparison, hopefully with soundclips...

[cap217]

Yes, MM's prices are nuts, but I have to say that I really like their version of the Woden OT...I'll be trying the Pacific A470 clone OT that I have soon, not going to be running it ultralinear...

I really want to try a Woden clone from Chris Merren at some point.

Masco,
Are you the guy that builds the JMJ-30's that everyone raves about?

Will report back on the MM Woden/Pacific A470 OT comparison, hopefully with soundclips...

Please do and compare. I got my ac30hw back from pisonic and it sounds great. Just curious on the former and if I want to swap.

[cap217]

V1 went micro phonic on me today during testing the amp. I decided to swap all the tubes to JJ from ruby. I only had JJ around so that's why. I put a balanced in v3. Can't test it yet but I hope it sounds better. I'm sure the ruby tubes were worn.

I took some pics too. Looks really high quality and pisonic did some great work. I also had the normal channel volume pot push/pull for some different year sounds. Not sure what he did there but it cleans up the bass.

Really surprised on how driven this thing can get in tb hot. I hear z wreck sounds but the wreck still had its own thing. Me is more stiff and more articulate. I also wish I could get more high end on the normal channel.


What xfirmers do you think they used stock?

[Turbojunkie]

Hi cap217,
I just did a little poking around, and maybe you already found this info, but just in case...from the Vox Showroom site on AC30HW's:

"Custom Handwound Transformers. North Coast Music supplied an original 60's era Woden output transformer to Vox to aid in the development of the "tone critical" output transformer"

With Psionic having so much experience with these models, I suppose they're the experts on how much a "MM" Woden would improve the amp...also, did you say what you're using for speakers with this amp?

I must mention that the amp I have is a TW Rocket build, so a bit different than an AC30HW....but will do the MM Woden vs. Pacific A470 test, because changing just the OT should still give an pretty accurate comparison of differences between the two types...but for the traditional AC30 sound, I'm guessing that the Woden types are better choice...the A470 is a Hi-Fi transformer, so I'm anticipating wider bandwidth, more highs and more lows, and a more "hollow" midrange...but, we'll see for sure when I can get around to swapping them.

The Psionic work looks great, have heard that Sozo's are wonderful in AC30 builds!

Also, I know that NOS glass is brutally expensive, but FWIW it has made HUGE difference in my amps...I've had excellent results fine tuning the frequencies, and Amperex & Mullards last a VERY long time...some of mine have 20+ years of use, and still just kill any new production stuff...Just something to think about.

Hope this helps in some way,
Take Care,
TurboJunkie

[cap217]

This amp when switched to TB and Hot gets microphonic. I swapped all the tubes and tested them. The old V1 was microphonic and the new ones arent. Is it possible that when I go to TB/Hot it makes the tube malfunciton?