Handwired AC-15 - A Quick Question

[DonMI6]

G'day guys, I've just been looking at the specs of the handwired AC-15 and noticed it has a 1/2 output switch. Just wondering if any owners have any comments on it, particularly, does it make a significant difference in volume & does it have an any appreciable effect on the tone.

I've got a AC15C1-BL which I'm loving, but a 1/2 output switch that effectively halved the volume would be very handy for playing at home, the price seems fairly reasonable & I really like the idea of a handwired amp!

[sax4blues]

I have two amps with power setting options, Mesa Express 5:50 and Orange Tiny Terror. My experience is the volume is a little lower, but not quiet by any means, not half, and at my house not significant in relation to what my family is hearing in other parts of the house. The character of the amp is different in the lower setting, they break up a little sooner but also in a different way. On the Mesa channel two when set to 5w has a really cool feel.

For me after playing these two amps for over a year the power switching feature would not be a factor in choosing an amp. If it's there that's fine but I would not seek it out.

btw I am gassing for that Blue AC15C1

[DaBender]

The general rule of thumb seems to be that halving the volume would require around a 90% reduction in power.

[max_twang]

I have that amp.

There are actually two pentode/triode switches on this amp -- one on the side of the EF86 channel, and one on the EL84s (the power tubes.)

When playing through the TB side (no switch there -- just the hi-cut knob), the switch on the EF86 side has no effect. Flipping the switch on the EL84 drops the volume a little, but certainly not close to half (based on the highly accurate db meter in my head.) I would describe the difference as the amp having substantially more "oomph" in pentode mode.

The volume drop is more significant when you go from pentode to triode on the EF86 channel. If you play with both switches in triode mode, the amp will be considerably quieter still. But this is also the setting that seems to get you the most clean headroom out of this amp.

I should mention that lack of clean headroom is sometimes a real shortcoming for this amp. I couldn't use it in some band situations when I needed to have louder, clean stage volume. OTOH, the crunch from this amp is a thing of beauty. It really rocks when you crank it up!

edit -- as far as tone goes, there's lots of variability. The EF86 side has a two position "bass shift" switch and a three position "brilliance" knob. Lots of tones there. The TB side has treble and bass knobs, and the hi-cut is a global control IIRC. Lots of ways to set things up...

[DonMI6]

Thanks for the replies so far!

My apologies for my badly worded question, when I said 'halve the volume' what I really meant was 'reduce the volume a bit'. I've got a little 5 watt SS amp that is a bit crap, but is at least 3/4 the volume of the Vox.

Max, that seems to be the beauty of these amps, very versatile. Headroom is not a major issue for me, I'm really using it for recording & am happy to get a good tone at a sensible decibel level.

[max_twang]

It definitely doesn't sound like a 5 watt SS amp :) IIRC, the Celestion Blue is pretty efficient, so the 7.5 watt setting still makes some noise (i.e. you can use it with a drummer.) BTW, I've plugged the output of my old Champ into the 2 12" speakers in my Twin, and that's got some volume too. It's not just the wattage rating that determines your volume.

If you can, try before you buy. I think you'll like it. I did a side by side with the AC15CC1 and there is no comparison. They're completely different amps IMO.

[burtonfan]

+1 on Max's posts. I also own this amp and it is incredible. I'm considering adding the AC30 version to my collection.

[max_twang]

Originally Posted by burtonfan

+1 on Max's posts. I also own this amp and it is incredible. I'm considering adding the AC30 version to my collection.

Yeah, I'd like the AC-30 too. I'd have a hard time justifying it though!

[jjkrause84]

Originally Posted by DaBender

The general rule of thumb seems to be that halving the volume would require around a 90% reduction in power.

More or less, but when people say that most don't stop to consider just what an incredible difference "doubling" the volume is! As a result, saying such things really isn't helpful at all, it's just sorta pedantic.

[jjkrause84]

Originally Posted by max_twang

I have that amp.

There are actually two pentode/triode switches on this amp -- one on the side of the EF86 channel, and one on the EL84s (the power tubes.)

When playing through the TB side (no switch there -- just the hi-cut knob), the switch on the EF86 side has no effect. Flipping the switch on the EL84 drops the volume a little, but certainly not close to half (based on the highly accurate db meter in my head.) I would describe the difference as the amp having substantially more "oomph" in pentode mode.

The volume drop is more significant when you go from pentode to triode on the EF86 channel. If you play with both switches in triode mode, the amp will be considerably quieter still. But this is also the setting that seems to get you the most clean headroom out of this amp.

I should mention that lack of clean headroom is sometimes a real shortcoming for this amp. I couldn't use it in some band situations when I needed to have louder, clean stage volume. OTOH, the crunch from this amp is a thing of beauty. It really rocks when you crank it up!

edit -- as far as tone goes, there's lots of variability. The EF86 side has a two position "bass shift" switch and a three position "brilliance" knob. Lots of tones there. The TB side has treble and bass knobs, and the hi-cut is a global control IIRC. Lots of ways to set things up...

I'm not sure you're talking about the same amp. Yours is the older handwired, I'd assume the OP is talking about the newer one.

[DonMI6]

Yeah, definately referring to the currently available model, in the the fawn tolex (I would prefer a classic black one though!.)
Appreciate the responses, my local shop has them advertised on line, next time I'm in town I'll see if they have them in stock.

[max_twang]

Oops -- I forgot they d/c mine and came out with a new one! Good catch JJ.

IIRC, the newer version is similar but Vox eliminated some of the various options I wrote about above. You should get similar sounds though, and I'm sure what I said about the wattage and volume is about right.

Let us know how you like the amp if you get to play it. I'm curious about how it compares to mine.

[jjkrause84]

Originally Posted by max_twang

Oops -- I forgot they d/c mine and came out with a new one! Good catch JJ.

IIRC, the newer version is similar but Vox eliminated some of the various options I wrote about above. You should get similar sounds though, and I'm sure what I said about the wattage and volume is about right.

Let us know how you like the amp if you get to play it. I'm curious about how it compares to mine.

I've owned the one you own and have played the new one...both are great, but are kinda different. The biggest change is getting rid of the EF86. I LOVED the EF86, but I also love the "Normal" 12AX7 channel. It's be really tough to decide. The new one has a defeatable master volume, which the old one lacked. For me, I vastly prefer the looks of the older handwired (which weren't fully handwired anyways)....much nicer. If the new amp came in the white tolex instead of fawn I'd be a clearer winner for me (but still a tough choice!).

[Sean65]

Half power settings on valve amps are usually thought of as a way of shaving off the clean headroom and getting the amp driving at lower volumes.

If you actually want lower volume for home use I'd think about getting an attenuator.