Getting more Bass from the Amp6

[mrdon]

I recently completed my foray into Class D by building an Amp6. It's been burning in now for about 72 hours and I have found the bass lacking to my ears. I am use to a vintage integrated tube amp with tone controls so that may be an issue, but I would like a little more "slam" coming from my Kirksaetters. Any ideas on how to improve bass on the Amp6 would be greatly appreciated.

[deandob]

Try a snubber across the 1800uF bulk capacitor. Check the snubber threads, I use a value of 2.2uF + 4.7 ohms in parallel with 0.1uF.

I dont necessarily get lots more bass, but the bass sounds cleaner & more dynamic.

Regards,
Dean

[D0Hbert]

what's the wattage for the 4.7ohm resistor? Thanks

[mrdon]

Thank you for the snubber suggestion.

Do you think my choice of 3.3uf input caps has something to do with the bass issue? I used Sonicaps (Gen 1) in place of the stock electrolytics. I am aware that some people find the Sonicaps slightly thin and bright instead of lush like an Auricap. What if I bypassed the 3.3uf Sonicaps (Gen 1) with a smaller Sonicap (Gen 2) as their website suggests? I wonder if that would improve things a little?

[Pano]

I have certainly not found the AMP6 to be bass shy, either to the ear or in measurement. But I always use a 10,000uF stiffener cap, sometimes two.

A lot of tube amps tend to be "loose" in the low end, allowing the speakers to overshoot on the bass notes. This can sound nice for small drivers (I don't know the Kirksaetters). Class-D amps tend to have much more control of the speaker than tube amps do. Thus a "drier" bass, but a more accurate bass. It can take some getting use to. For some speakers a looser amp will actually be better, as it adds some low end that small drivers are often missing.

That said, try adding a good quality stiffener cap to the regulated side of the supply and see if that helps. It's easy to do and undo.

Better input caps can also help the bass. There won't be more of it, but it can sound much fuller. I find even good electrolytics sound dry in the lower registers. YMMV

On a technical note, can you measure the DC voltage on the regulated and unregulated side of the power supply? If your unregulated voltage isn’t high enough, you’ll certainly loose bass and dynamics.

OK, time to stop. Much more than you wanted to know!

[niiico]

Originally posted by panomaniac
I have certainly not found the AMP6 to be bass shy, either to the ear or in measurement. But I always use a 10,000uF stiffener cap, sometimes two.

Hi,

I'm new to this forum and I read your answers with a lot of attention...

I would like to understand where do you connect this "stiffener" cap (I don't understand the exact meaning of this word...)?
Is it connected in parallel to C1819?
Should it be as close as possible to C1819 or is it possible to use 10 cm of wire to connect this cap?

Actually, I'm about to finish my AMP6 and I would prefer to make the modification before to integrate it in a small case.

Thanks

[Pano]

Bonjour Niiico,
The stiffener cap should go as close to the board as you can get it. Basically you want a low resistance, low inductance path from the cap to the board so that energy can be supplied quickly to the amp.

10 cm is a bit long. 1/2 that would be better. But if you can use a large wire, it will help. Yes, it is connected in parallel to C1819

The "stiffener" cap works as an energy reservoir to supply the amp during loud passages and peaks. Even though the AMP6 has an onboard regulated supply, it is not perfect. Adding a large capacitor(s) helps to keep the voltage stable. It supplies the peak energy needed to give you good dynamics and bass. To the ear it results in a stronger, more dynamic amp with a fuller low end..

Bref, ca rende l'ampli moin "mou", si tu veux- plus rigid.
Ca n'est pas au gout de tout le monde, mais je le trouve beaucoup plus realiste et musical.

[mrdon]

On a technical note, can you measure the DC voltage on the regulated and unregulated side of the power supply? If your unregulated voltage isn’t high enough, you’ll certainly loose bass and dynamics.

Which is the regulated side and which is the unregulated side of the power supply?

[Pano]

The regulated side is C1819, the gold and black Panasonic cap. Unregulated is C99, the big black cap.
Ground is common between them.

[Eva]

It may seem a bit silly, but I use an equalizer for these duties