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Douk Audio Invite You to Create Another Amplifier with Both HPF and LPF together!!!

Douk Audio

Douk Audio

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Hello all ASR members,

Last year, we got inspiration here and we released the A5 amplifier with a high pass filter based on all your opinions.

We are happy to let you know that it is very popular, it is your valuable opinions that made it available in such a short time. On behalf of the Douk Audio Team, we want to express our sincere thanks to all of you.

Now, we collect some ideas in the A5 thread and from some A5's users and decide to design another amplifier with both HPF and LPF. If you have any other suggestions please feel free to leave your ideas and we believe that your valuable opinions will help create another popular amplifier.

Here are some initial thoughts not determined yet.

1. Chips: TPA3255 or Module design (Purifi/NCore/Infineon)
2. Inputs: RCA and XLR
3. Outputs: speaker jacks and AUX or RCA (SUB or Full-frequency)
4. With volume control and support bypass
5. With a high pass filter to control (with scale value) the main speaker output
6. With a low frequency filter (with scale value) to control the main speaker output or AUX/RCA output
7. With 12V trigger input
8. With loudness adjustment
9. Internal or external power supply
10. What is the acceptable selling price?
11. The chassis may be bigger than all the TAP3255 amplifiers we sell now.
12. We may create the matched DAC/Preamp with this amplifier in the near future, any advice on them?

Thank you again! All suggestions are welcome! :)
 
JSmith said:
Selling price will very much depend on whether it is TPA based or other.
Click to expand...
Yeah, TPA3255 amplifiers are so many many now but the Purifi/NCore module will cost too high...Maybe Infineon will be a compromise :facepalm:
 
Douk Audio said:
Yeah, TPA3255 amplifiers are so many many now but the Purifi/NCore module will cost too high...Maybe Infineon will be a compromise :facepalm:
Click to expand...
True, but then I've seen better measurements from TPA based amps in comparison to Infineon. So maybe stick with that if Purifi/NCore put up the price too much.

Could consider a standard version with TPA's and a more premium version with Purifi/NCore? Of course that assumes Purifi/NCore will be happy to supply the modules...

If going with TPA's, make sure it's done well and implement PFFB... or you won't compete with the current offerings that do.


JSmith
 
Another one! :)

Seems to me that there are a lot of good budget amps around (< 200), and also plenty of more expensive amps ( > 800)
If you are aiming for one of those sectors then you have to have something special to offer.

Very interested in that "loudness" comment - what do you mean?

Also seems to me that the middle ground is less well represented with frequency and load independent amps that provide a decent amount of power (>100W in 8 Ohms) with good measurements (low noise and distortion) and good thermal management. A design that implies robustness and a long life. An amp that I can keep for years and not worry whether new speakers will be difficult loads or not. A well measuring (upper quartile) workhorse.

I don't mind what technology is inside it, as long as it delivers.

A high-pass filter sounds like a great idea, I'd like that.
If you have a low-pass filter then you imply that the amp will be driving a passive subwoofer - do you really mean that? If so then you need to be able to deliver more power and the questions about thermal management and robustness are more important.
Perhaps better to have a pre-amp / DAC with a sub out and let your new amp just drive the main speakers ... you can design a new amp dedicated to running subwoofers if you like.

Nice to have: balanced inputs, trigger, quality speaker binding posts with enough space, small footprint but not cramped ...

Robust, well measuring, all features for a reason. Good value (rather than cheap or expensive)
 
Are you looking for feedback on the A5 that might be useful for the new model? If so, here are my subjective impressions of the A5.

  • The loose window (sans sticker) seems like a hazard to me since it isn’t secured. It should have a friction hinge or some other means to stay attached and closed when installed. AFAIK, there is no precedent in other brands for a loose compartment door.
  • I don’t think most external amplifiers and subwoofers use 1/8” headphone jack for input, so I think RCA(s) would be more appropriate for the AUX output. I’m using an adapter for my subwoofer as it uses RCA. Is it intended to be used with headphones, too? If so, that makes more sense to me.
  • I agree with other opinions that the high-pass frequency knob shouldn’t be as prominent as the volume knob. If it remains on the front, which doesn’t seem inherently bad to me, consider making it smaller.
  • I agree with other opinions that it would be better if the high-pass frequency knob had discrete frequency indicators, e.g. labeled notches. To be fair to Douk, though, all the subwoofers I’ve owned have done the same thing; that is, provided a continuous knob with lower and upper labels only. It’s a shame.
  • As with my other observations, this opinion is subjective. I used a fixed-frequency tone generator to calibrate the high-pass frequency by hand, and could hear the undesired frequencies more than expected. For example, I had to crank the HPF knob more than halfway up to adequately attenuate 40 Hz. I am very ignorant on this topic, but could a higher-order filter be implemented?
  • The AC power cord (from wall to adapter) seems thinner than 99% of U.S. audio equipment cords, in my experience. Consider using a thicker gauge of wire and/or thicker insulation, whatever is appropriate.
  • Given how impressively small the A5 is, I think it would be better if the power supply were integrated.
  • All that said, the A5 amp sounds great to me. I listen near-field with 89 dB sensitivity speakers.
 
1) I prefer an external power supply keeping with upgradability and because i already have some external decent power supplys laying around...
2) A remote would be a good idea imo, not essential if you develop a nice preamp but it would sure be a nice thing.
3) If you need a bigger case maybe you could use the q11s as it could make a nice stack + maybe it could keep the cost down? And you could also use the same one in a future preamp or future products in the same line
4) If you don't have the room for xlr maybe you can use trs.
5) Using Purifi/NCore would be very nice but i think maybe the price isn't worth it. Maybe in a different, more high end line of products? Infineon i don't think it's worth it really, not really much better than tpa3255... Maybe try some sort of digital amplifier in the future? Not many of those in the market right now, specially in a more budget/ affordable realm.
6) Would using discrete components make the price too high? (i have no idea) That could be an improvement!

Keep up the good work!
 
I’d like to see one of these amps with Home Theater Bypass, given the low/high pass features. The only real competition is Parasound when it comes to HT Bypass with full bass management, but I think there are plenty of folks who are interested in this functionality.
 
Are the HP and LP filters 12dB or 24dB (best)?
cjh
 
I am a proud owner of the A5. It is an excellent product, and it deserves some recognition.
The only two features that I miss are auto on/off (more important) and volume bypass. Everything else is optional to me.
I recommend you make a poll on 12v trigger vs auto on/off. I very much prefer auto on/off, but opinion varies.
 
I would bet on a TPA3251 power DAC in PBTL supporting LDAC since you did not offer it on the Douk A5 pro.... I would make a particular effort on the PFFB implementation and I would opt for quality flat-wire inductors with OP amp in DIP8 while integrating your two combined filters. I prefer an excellent amp @ $ 300 rather than yet another TPA325X on a saturated market

I will go even further by playing the card of a partnership with allo.com which had developed a very promising TPA3255 but which was abandoned....why not and just do it :):):)
 
PURE DIRECT ANALOG STEREO AMP

PURE unadulterated frequency amped up, lowest noise distortion possible. 50 watts per channel 8 ohms, Only Volume control, possibly a remote control for volume if it`s not going to cause complications with noise distortion.

Simplicity wins KISS ( Keep It Simple Stupid ) no LED screens to add noise no LED Lights ether they are usually to bright anyway and ruin a romantic room setting...

The average music lover does not want Balanced cables those are for a special breed and or big audio industry professionals who are always plugging cables from one piece of equipment to another.

Simple easy to use 3.5 mm Aux out port at rear possibly pointing up to keep appearance stylish, RCA inputs at rear, speaker wire connection nothing fancy but high quality, and nothing else that adds to possibility of noise on the system if that means no power switch then that's that whatever you have to do to make it as PURE as possible please consider that the priority.

Many people have home theatre amps and are missing out on the Pure Direct analog Mode, I own the Harman Kardon AVR 140 it has a Pure Direct Analog mode but I can hear some slight hissing in the tweeters with volume about 1/3 level and nothing plugged in or paused. So I would be interested in a small amp with the above mentioned Purity.

External Power supply.

It would also be a great idea to sell them straight out of the Amazon Warehouse as returns and warranty issues are a no brainer no stress most people now this and you will sell more items.

If you charge for shipping returns to Amazon warehouse then consider the possibility of missing out on sales when I see free returns it clearly spells out CONFIDENCE !

A removable glass window at the top for show of the internals and the option to remove it to keep the heat down for long sessions.


If you have any further curiosity of my insights feel free to contact me directly.

Thank you for your time and have a great day !
 
Last edited:
Please also consider using the purest form of solder for all audio output stages.

This is not my area of specialty but I`ve heard silver alloy solder is much better for audio signals..

Copper solder is also worth considering looking into ?

Silver solder & Gold plating might also improve marketing... But purity should be priority.

A true professional in all aspects of soldering is actually needed for a through detailed life experience answer...
 
Last edited:
Question. Have you ever considered designing a volume control that actually stated the watts being used by the speakers... ?

A volume read out that stated 5 watts or 5.25 watts would make at more logical connection to the average person as far a volume output goes.
 
Last edited:
Douk Audio said:
Hello all ASR members,

Last year, we got inspiration here and we released the A5 amplifier with a high pass filter based on all your opinions.

We are happy to let you know that it is very popular, it is your valuable opinions that made it available in such a short time. On behalf of the Douk Audio Team, we want to express our sincere thanks to all of you.

Now, we collect some ideas in the A5 thread and from some A5's users and decide to design another amplifier with both HPF and LPF. If you have any other suggestions please feel free to leave your ideas and we believe that your valuable opinions will help create another popular amplifier.

Here are some initial thoughts not determined yet.

1. Chips: TPA3255 or Module design (Purifi/NCore/Infineon)
2. Inputs: RCA and XLR
3. Outputs: speaker jacks and AUX or RCA (SUB or Full-frequency)
4. With volume control and support bypass
5. With a high pass filter to control (with scale value) the main speaker output
6. With a low frequency filter (with scale value) to control the main speaker output or AUX/RCA output
7. With 12V trigger input
8. With loudness adjustment
9. Internal or external power supply
10. What is the acceptable selling price?
11. The chassis may be bigger than all the TAP3255 amplifiers we sell now.
12. We may create the matched DAC/Preamp with this amplifier in the near future, any advice on them?

Thank you again! All suggestions are welcome! :)
Click to expand...
I bought mine from Douk store on aliexpress (based on the PFFB implementation) and very happy with the sweet high end!
I use 92dbw sensitive speakers (Ref3A DeCapo I)
I would pay more for a unit that had:
1: balanced outputs
2: clipping/vu meter led ladder
3: tone controls with defeat switch

great job on the A5!
 
Good afternoon, everyone. Here are my humble opinions:

1. Chips: TPA3255 or Module design (Purifi/NCore/Infineon). NcoreX/Purifi. There are too many options from many brands offering different implementations of the excellent TPA3255
2. Inputs: RCA and XLR. Yes, to both of them.
3. Outputs: speaker jacks and AUX or RCA (SUB or Full-frequency). Indistinct. I think 95% of use cases involve active subwoofers with their own low-pass filter.
4. With volume control and support bypass. Yes! But the volume control should be of very high quality (ALPS for example) or design a matching preamplifier to pair with this pure power amplifier.
5. With a high pass filter to control (with scale value) the main speaker output. Without a doubt! For proper subwoofer integration, I consider it essential.
6. With a low frequency filter (with scale value) to control the main speaker output or AUX/RCA output. Indistinct. I think 95% of use cases involve active subwoofers with their own low-pass filter.
7. With 12V trigger input. Yes.
8. With loudness adjustment. If possible. Bass/Trebble too.
9. Internal or external power supply. NcoreX/Purifi modules deserve an internal power supply.
10. What is the acceptable selling price? It doesn't necessarily have to be a cheap product. I think if you cover your costs and establish an adequate profit margin, you can offer a competitive price.
11. The chassis may be bigger than all the TAP3255 amplifiers we sell now. Yes, it should definitely be larger, even to promote good heat dissipation management. It doesn't need to take up a full rack unit, but a larger size would be appreciated.
12. We may create the matched DAC/Preamp with this amplifier in the near future, any advice on them? I think it's an excellent idea. In that case, I would allocate the preamplification capabilities to that unit, leaving it as a pure power unit. If a preamplifier is being developed, some digital inputs would also be appreciated, such as coaxial, optical, HDMI, and USB, paired with a competent DAC chip, such as the latest-generation Sabre or AKM.
13. VU Meters. Please! A pair of elegant analog VU meters in the best 70s/80s style would greatly contribute to the aesthetics.

Thank you for considering our points of view as users and customers!!
Best regards.
 
Douk Audio said:
Purifi/NCore module will cost too high...Maybe Infineon will be a compromise :facepalm:
Click to expand...
This does not have to be a compromise. Infineon has the right audio chip solution for every requirement.

1000028604.png


This chip for example is not often used and is actually a good alternative to the TPA325x



These have very high Power Ratings
 
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