I wish to modify the tone stack in my Ashdown Mag 300 head.

[Kobaia]

Hello all,

I'm a bassist living in Edinburgh, Scotland. My current, and first 'proper', rig comprises an Ashdown Mag 300 head and two Ashdown 112 cabs.

I find my amp has a rather boring tone. I feel that the tone shaping controls are less than perfectly centred across the frequency spectrum. In general, I prefer the tonal shaping capabilities of Ampeg amps. I know I cannot make my Ashdown into an Ampeg, but I would like to modify my amp so that the tone controls are slightly more useful.

I've found a schem for my amp here at the bottom of this page;

http://music-electronics-forum.com/t28046/#post307779

On tmy Ashdown, there are five EQ controls. They are, and their frequencies are;

Bass - 100 Hz
Mid - 650 Hz
Treble - 7 kHz

Lo Mid - 340 Hz
Hi Mid - 1.6 kHz

This doesn't seem like an ideal spread to my ears. I always feel that Ampeg gear has a sweeter mids response for one thing. My Ashdown has quite muddy, boomy lows. I guess this is because the Bass control centres on 100 Hz. There is also a lack of upper-mids shaping due to the void between 650 Hz and 1.6 kHz in the range of the controls.

By contrast, the frequencies catered for by typical Ampeg controls are;

Bass - 40 Hz
Midrange (switchable at) 220 Hz, 450 Hz, 800 Hz, 1.6 Hz and 3 kHz

Treble is at 4 kHz

Ideally I would have the Ashdown 'retuned' so that the bass control was at 40 Hz, the mid control at 800 Hz 'lo mids' at 300 Hz, the 'hi mids' at 1.2 kHz or so and the treble at 4 kHz.

Is this possible just from substituting the caps and resistors affiliated with each control on the schematic?

Thanks in advance,
Kobaia

[Jazz P Bass]

Yeah you could redesign the circuits.

It sounds like a lot of hit & miss component swapping to get it right.

Have you considered a parametric EQ pedal in the FX loop?

[Kobaia]

I hear you, to a degree.

But, surely the technology in the tone stack here is fairly well understood? I have the Duncan tonestack calculator on my laptop, and this circuit looks more complex than that as it involves transistors hence my unwillingness to plunge in at the deep end.

In looking at the 'hi mid' and 'lo mid' controls in particular, they appear to be identical circuits, with the values of C36 (hi) and C24 (lo) swapped out, and the values of C35 and C25 swapped out. Perhaps I'm barking up the wrong tree here, and I certainly won't start blindly swapping capacitors if I hear nothing else.

[J M Fahey]

Hello all,

I'm a bassist living in Edinburgh, Scotland. My current, and first 'proper', rig comprises an Ashdown Mag 300 head and two Ashdown 112 cabs.

I find my amp has a rather boring tone. I feel that the tone shaping controls are less than perfectly centred across the frequency spectrum. In general, I prefer the tonal shaping capabilities of Ampeg amps. I know I cannot make my Ashdown into an Ampeg, but I would like to modify my amp so that the tone controls are slightly more useful.

I've found a schem for my amp here at the bottom of this page;

http://music-electronics-forum.com/t28046/#post307779

On tmy Ashdown, there are five EQ controls. They are, and their frequencies are;

Bass - 100 Hz
Mid - 650 Hz
Treble - 7 kHz

Lo Mid - 340 Hz
Hi Mid - 1.6 kHz

This doesn't seem like an ideal spread to my ears. I always feel that Ampeg gear has a sweeter mids response for one thing. My Ashdown has quite muddy, boomy lows. I guess this is because the Bass control centres on 100 Hz. There is also a lack of upper-mids shaping due to the void between 650 Hz and 1.6 kHz in the range of the controls.

By contrast, the frequencies catered for by typical Ampeg controls are;

Bass - 40 Hz
Midrange (switchable at) 220 Hz, 450 Hz, 800 Hz, 1.6 Hz and 3 kHz

Treble is at 4 kHz

Ideally I would have the Ashdown 'retuned' so that the bass control was at 40 Hz, the mid control at 800 Hz 'lo mids' at 300 Hz, the 'hi mids' at 1.2 kHz or so and the treble at 4 kHz.

Is this possible just from substituting the caps and resistors affiliated with each control on the schematic?

Thanks in advance,
Kobaia

Sorry to hear that but you wonīt get what you want.

The problem does not lie in the tone controls per se, which are not bad at all, but in speaker/cabinet sound and an indifferent plain SS power amp driving them.

You can test it yourself: at some rehearsal roow which has one, put your Ashdown and cabinets side by side with a classic Ampeg, set both flat , so as to fully remove amp EQ from the equation, and play both.

You will still clearly listen to that difference whih is bothering you.

In a nutshell:
1) those single 12" cabinets are quite smaller (and so smaller sounding) than the typical 8x10" or 2 x 15" or 15" + 4x10" youīll find paired with "good" Ampegs. And thatīs the main difference.

Your 12" cabinets are not bad, but definitely not in the same league.

You have a bass boost button but it will not work miracles, just help a little, and as you noticed, add mud along with bass.

And forget about the stupid "Sub Bass" generator, guaranteed path to fake bass which never was there to begin with and which canīt be reproduced by any speaker.
What were they thinking?

2) classic tubed Ampegs have very low damping factor, around 1, and make cabinets sound rounder, punchier and smoother at the same time, while your Ashdown has a good SS Hi Fi type amp, with very high damping factor (dry sounding bass).

That said, JPB suggestion of a parametric EQ in the loop is the most practical solution, not only because of the wide adjustment range, but because you can play with Q, which at higher values can mimic the response of poorly damped speakers which is an often ignored aspect of tube sound.

You can also add a compressor in the loop.

Tube amps naturally compress; *some* Bass amps add that to help, yours does not.

Those are all parts of the "flavor" you are trying to achieve.

Good luck.

[Kobaia]

Hello Juan,

Thanks for the in-depth response.

Apropos the 'sub bass' generator, it sounds a lot like a poorly-tracking sub octave pedal to my ears. On my head it is paired with an 'overdrive' knob that mixes in an anaemic set-gain Muff-style fuzz. Ashdown have their quirks I guess. The sub bass feature is now called 'classic' in some literature. I assume they were going for a DBX120-family deal.

I presume there is no physical or electronic modification I can perform to one of the 112 cabs?

[J M Fahey]

Not really.

But try the electronic add-ons (compressor + parametric EQ set tp high Q curves).

At least to test the concept, spending 0$, try the software path.

Record a short bass demo, your choice, part of songs you actually play, straight into the PC.

Then loop that so it never stops, load some compressor and EQ plugins in your favorite sound software and play at will until you get a sound you like.
Always eproducing the sound through bass amp and speakers.

I bet you will find something you like, then buy equivalent cheap audio processors (Behringer or similar ones) and reproduce that live.

Best luck.