Hi,
I've just bought an AC15HW1x amp.It sounds good but what I really wanted was a vox-based "boutique" style amp (like a Top Hat, Dr Z or 65 amps) but I live in Australia and those amps are prohibitively expensive here.
My question is, are there some simple (reversible) mods I can make to the circuit to make the amp sound tighter, take pedals better and just generally have that modded-vox sound like the brands I mentioned? I have already removed the bright cap and changed the speaker to a G12H anni which has got me part of the way there but it's not enough. I guess I'm asking, what makes those boutique amps sound the way they do?
Thanks and hope this question isn't too sacrilegious.
Vox AC15HW mods to sound "boutique"?
Moderators: pompeiisneaks, Colossal
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Colossal
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Re: Vox AC15HW mods to sound "boutique"?
Here is a schematic so we can have a meaningful discussion. What kind of guitar and pickups are you using? Check out C5 and C6, the output tube coupling capacitors. Consider reducing those to 22nF to tighten the bass response for a guitar with humbuckers and/or a hot input signal. Do you prefer the EF86 channel or the Top Boost Channel?
As to what makes boutique amps sound the way they do, I would say good quality transformers, then tubes (try rolling different brands or NOS tubes to suit), and certainly parts. The AC15HW1 is the so-called "handwired version", so I would have expected this amp to be a cut above Vox's budget PC board based offerings
As to what makes boutique amps sound the way they do, I would say good quality transformers, then tubes (try rolling different brands or NOS tubes to suit), and certainly parts. The AC15HW1 is the so-called "handwired version", so I would have expected this amp to be a cut above Vox's budget PC board based offerings
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Re: Vox AC15HW mods to sound "boutique"?
Hi. Thanks for the reply. I have the AC15HW1x which is different to the one you have attached (the AC15TV). They're probably similar but mine has no EF86 channel - it's all 12ax7s with this amp. I use the normal channel as a pedal platform for a strat. I find there is too much bass which I can't dial out (reducing those coupling caps is a good idea. What value do you suggest?). Also even in though I'm in the normal channel with the bright switch off, I find there is still a high frequency that makes OD pedals sound fizzy. Any suggestions welcome.
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Colossal
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Re: Vox AC15HW mods to sound "boutique"?
My apologies, I just noticed that!
I would reduce the output coupling caps down to 22nF and see how that goes, especially if you are finding it top heavy with a strat. The GH1230 is punchy, so leaning out the back end of the amp will help keep it tighter. Also, to dial out some of the excessive Voxy crispy creme fizz, you might consider changing the phase inverter bias resistor (1k2) to something more like 910 or 820R.jazrok wrote: ↑Mon Jan 27, 2020 4:07 amThey're probably similar but mine has no EF86 channel - it's all 12ax7s with this amp. I use the normal channel as a pedal platform for a strat. I find there is too much bass which I can't dial out (reducing those coupling caps is a good idea. What value do you suggest?). Also even in though I'm in the normal channel with the bright switch off, I find there is still a high frequency that makes OD pedals sound fizzy. Any suggestions welcome.
Re: Vox AC15HW mods to sound "boutique"?
Thanks Colossal- good suggestions. I'll give them a try - esp interested in the anti-fizz mods you suggest. I changed the the V1 cathode bypass cap from 22uf to 2.2uf and that seems to have sorted out the boomy bass. I'm also thinking of halving the tone cut cap to allow more mids in when the treble is cut. Otherwise that knob is pretty useless imho.
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Stevem
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Re: Vox AC15HW mods to sound "boutique"?
Overall it sounds to me like you need a little more then just a 15 watt amp!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
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Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Vox AC15HW mods to sound "boutique"?
I don't know much about the HW series but the wood of the cab may also contribute to the "boutique" sound, if any such thing exists.
By reading your original post, I wonder if what you're about isn't the "EF86" sound, rather?
In that case, one way to go could be to sell this amp and have someone build a repro. of one vintage circuit.
Possibly you can do it yourself as well, on the basis of your amp. Can you pull out the board easily & without any non reversible operation? That would allow for making your own board with the right circuit - provided the controls also "match" ...
... these doubtfull thoughts provided as generalities without any consideration for practical issues (your mileage may vary.)
By reading your original post, I wonder if what you're about isn't the "EF86" sound, rather?
In that case, one way to go could be to sell this amp and have someone build a repro. of one vintage circuit.
Possibly you can do it yourself as well, on the basis of your amp. Can you pull out the board easily & without any non reversible operation? That would allow for making your own board with the right circuit - provided the controls also "match" ...
... these doubtfull thoughts provided as generalities without any consideration for practical issues (your mileage may vary.)