PopPulse T-amp with Remote - modding

[ChuckT]

ChuckT, have you tried the MKT1817 caps in the output filters of the Tripath amps yet? They are smaller than the MKT1822. They seem to sound very similar to me, but they fit better.

Nope, seems like max value is 1uF. If they sound the same, use the one that fits.

 

[RaZmaTaZ]

Power Cap

ChuckT,

Got a question for you. When you replaced the stock Poppulse power capacitors, there was a resistor on the underside. Did you use back the resistor or did you replace that too?

I think I found out where the lack of bass on the Poppulse stems from. The following post from panomaniac may explain further:

This is an interesting subject. High or Low damping factor? I like the high damping factor, but I tend to use "loose" speakers. A lot of guys here don't like the sound of big caps in the PSU. I suppose the lower damping gives stiff speakers (e.g. Fostex, Lowther, etc.) a little more "swing".

I was talking to a speaker designer buddy last night about this. He says that with stiff speakers and/or low listening levels - low damping factor sounds better.High damping and stiff drivers with a low power amp can equal NO bass. Tube amps usually have a low damping factor, thus the "musicality".
Not until you get a very powerfull amp with high damping does the bass come back.

Bob Carver, of Carver Amps, used to claim he could imitate the sound of any amp just by changing the damping factor of his amps.

For me, the large PSU sounds better, not just tighter bass, but better dynamics and a wider soundstage. But that might not be the case with some speakers.

I'd like to know what you find in your PSU experiments.

And in another post:


Right, seems to be speaker dependant. And a matter of taste, too. Big cap = tight dry bass. Small cap = loose, more generous bass.

I replaced the stock power cap on the Trends (to a JVC 3300uf 16v) last weekend and got an unexpected surprise. There seem to be a sharp roll off of the bass at abt 100Hz. Everything else sounded full except the kick drums and low bass guitar.

So I will now add the Rubycon ZL 470uf in the empty slots and see what happens. And if still a problem, then replace the ELNA 4700uf power caps with a 2700uf or 3300uf.

 

[ChuckT]

Re: Power Cap

ChuckT,

Got a question for you. When you replaced the stock Poppulse power capacitors, there was a resistor on the underside. Did you use back the resistor or did you replace that too?

I think I found out where the lack of bass on the Poppulse stems from. The following post from panomaniac may explain further:





I replaced the stock power cap on the Trends (to a JVC 3300uf 16v) last weekend and got an unexpected surprise. There seem to be a sharp roll off of the bass at abt 100Hz. Everything else sounded full except the kick drums and low bass guitar.

So I will now add the Rubycon ZL 470uf in the empty slots and see what happens. And if still a problem, then replace the ELNA 4700uf power caps with a 2700uf or 3300uf.

Nope, I put it back. It is just a bleeding resistor to remove the caps stored energy after you turn it off. Should have no impact to sound, I believe.

Of cause the power cap makes a big diff, but I think the requirement for a discrete and class-d amp is different, so different cap values and cap quality have different affect on the amps. I don't know what is the quality of the JVC cap, how about trying a good old 4700uf ZL in the Trend.
Yes, put that 470uf/35V ZL (or any good quality cap) in the empty space in the Pop.

 

[RaZmaTaZ]

Re: Re: Power Cap

Nope, I put it back. It is just a bleeding resistor to remove the caps stored energy after you turn it off. Should have no impact to sound, I believe.

Of cause the power cap makes a big diff, but I think the requirement for a discrete and class-d amp is different, so different cap values and cap quality have different affect on the amps. I don't know what is the quality of the JVC cap, how about trying a good old 4700uf ZL in the Trend.
Yes, put that 470uf/35V ZL (or any good quality cap) in the empty space in the Pop.

Hi ChuckT

Fitted in the 470uf/35v ZLs over the weekend. Very slight improvement. I think the Poppulse is way too complicated in its design. Too many caps? Is it correct to say that of the 6 e-caps there, 2 are for input to the volume control device, 2 for the LM4562 op-amp and the last two for the TA 2022 chip? Is that why you went for bypassing the op-amp all together?

I ordered the mkt1817 (as hinted by dweekie) from RS but its taking ages to come in. Will replace the BGs with them and see if shakes the bass a bit more. Otherwise, on a last resort, do you I should change the op-amp? If so, which op-amp do you think will pump up the bass?

PS. The bass suddenly came in on the Trends with the JVC. I think the amps have not been broken-in. (Read somewhere here that the Tripath chips are notorious for sounding odd during break-in period.)

 

[peepoo]

PopPulse as a power amp??

Can I bypass the pre-amp section and use it as power amp?

Thanks,

 

[ChuckT]

Re: PopPulse as a power amp??

Can I bypass the pre-amp section and use it as power amp?

Thanks,

Of cause. Very easy. You can choose to keep the opamp as buffer or bypass it.

 

[ChuckT]

Re: Re: Re: Power Cap

Hi ChuckT

Fitted in the 470uf/35v ZLs over the weekend. Very slight improvement. I think the Poppulse is way too complicated in its design. Too many caps? Is it correct to say that of the 6 e-caps there, 2 are for input to the volume control device, 2 for the LM4562 op-amp and the last two for the TA 2022 chip? Is that why you went for bypassing the op-amp all together?

I ordered the mkt1817 (as hinted by dweekie) from RS but its taking ages to come in. Will replace the BGs with them and see if shakes the bass a bit more. Otherwise, on a last resort, do you I should change the op-amp? If so, which op-amp do you think will pump up the bass?

PS. The bass suddenly came in on the Trends with the JVC. I think the amps have not been broken-in. (Read somewhere here that the Tripath chips are notorious for sounding odd during break-in period.)

Yes, I skip the opamp because I have enough gain.
The output from the volume chip is low, add some gain by the lm4562.

 

[peepoo]

Can you guide me how to do the bypass? I'm a newbie and don't know where to start.

Thank you very much,

 

[peepoo]

Oh, I see. I read all the post again and found my answer. Thanks.

 

[ChuckT]

Oh, I see. I read all the post again and found my answer. Thanks.

sorry, too busy to reply.
I glad u got the answer, please tell use how it sounds afterwards.

 

[RaZmaTaZ]

ChuckT,

There is an IC on Poppulse (near the signal input jumpers) marked 62429. Is this a 'serial data control dual electronic volume' electronic volume control chip?

I swapped the LM4562 with a OPA2107, slight improvement in bass but it is still lacking. I put LM4562 in a DAC707 with the Trends as the amp, and since the Trends has no op-amp, I suppose I was listening to the LM4562 'directly.' Sounds awesome, with very good bass too. The OPA2107 on the DAC707 was a bit more bass for my speakers. Maybe better with my other smaller speakers.

I suppose the Poppulse has too many circuits and the bass could be attenuated by the volume control unit?

 

[ChuckT]

ChuckT,

There is an IC on Poppulse (near the signal input jumpers) marked 62429. Is this a 'serial data control dual electronic volume' electronic volume control chip?

I swapped the LM4562 with a OPA2107, slight improvement in bass but it is still lacking. I put LM4562 in a DAC707 with the Trends as the amp, and since the Trends has no op-amp, I suppose I was listening to the LM4562 'directly.' Sounds awesome, with very good bass too. The OPA2107 on the DAC707 was a bit more bass for my speakers. Maybe better with my other smaller speakers.

I suppose the Poppulse has too many circuits and the bass could be attenuated by the volume control unit?

Yes, check link.

http://documentation.renesas.com/eng/products/assp/rej03f0209_m62429pds.pdf

The LM4562 is a very good opamp.
Had a talk to Wu of the PopPulse shop, he said the lm4562 sounds better with higher gain, he went to 8x, current setup is 2x, I believe.

 

[RaZmaTaZ]

Yes, check link.

http://documentation.renesas.com/eng/products/assp/rej03f0209_m62429pds.pdf

The LM4562 is a very good opamp.
Had a talk to Wu of the PopPulse shop, he said the lm4562 sounds better with higher gain, he went to 8x, current setup is 2x, I believe.

Thanks ChuckT. Err so do I replace the lm4562 with an op-amp that will do better at 2x gain? Or do I find out how to increase the gain to 8x? Replace a resistor maybe?

 

[ChuckT]

Increase the feedback resistor to increase gain for each channel.
If u don't know which one, you'll have to do a little research of your own. They connect the output pin and the negative input pin.

In addition, there might be improvement if you put a nice 0.1uf cap across the +/- power pins.

 

[ChuckT]

If u bypass the opamp stage LM4562, I suggest lower the feedback resistor from 20k to 10~15k to increase the gain of the TA2022.

In fact, I wonder if it is a good idea to increase the gain of TA2022 anyways, because the tripath uses an internal opamp and PopPulse set it at unity gain for the opamp.
I think some opamp do not sound good with unity gain.

I lower the feedback resistor from 20K to 10K and it seems the bass and detail improve a bit, could be my imagination.

 

[ChuckT]

If u bypass the opamp stage LM4562, I suggest lower the feedback resistor from 20k to 10~15k to increase the gain of the TA2022.

In fact, I wonder if it is a good idea to increase the gain of TA2022 anyways, because the tripath uses an internal opamp and PopPulse set it at unity gain for the opamp.
I think some opamp do not sound good with unity gain.

I lower the feedback resistor from 20K to 10K and it seems the bass and detail improve a bit, could be my imagination.

Ops, that should be lower the INPUT resistor, not feedback.

 

[RaZmaTaZ]

Ops, that should be lower the INPUT resistor, not feedback.

Ok, so you suggest to bypass the LM4562 and drop the input resistor to 10k? What is the effect on the volume of the system? As in what would be the drop in db level? For example, if I usually listen to the Poppulse at -36db, would the same level of loudness without the LM4562 be at -33db or -30db?

 

[TheDealer]

Originally posted by panomaniac
This is an interesting subject. High or Low damping factor? I like the high damping factor, but I tend to use "loose" speakers. A lot of guys here don't like the sound of big caps in the PSU. I suppose the lower damping gives stiff speakers (e.g. Fostex, Lowther, etc.) a little more "swing".

I was talking to a speaker designer buddy last night about this. He says that with stiff speakers and/or low listening levels - low damping factor sounds better.High damping and stiff drivers with a low power amp can equal NO bass. Tube amps usually have a low damping factor, thus the "musicality".
Not until you get a very powerfull amp with high damping does the bass come back.

Bob Carver, of Carver Amps, used to claim he could imitate the sound of any amp just by changing the damping factor of his amps.

For me, the large PSU sounds better, not just tighter bass, but better dynamics and a wider soundstage. But that might not be the case with some speakers.

I'd like to know what you find in your PSU experiments.

And in another post:


Right, seems to be speaker dependant. And a matter of taste, too. Big cap = tight dry bass. Small cap = loose, more generous bass.

Hi Chuck and Razmataz, just looked again into this thread and read this interesting quote from panomaniac (thanks chuck) and want to add my expereciences testing the Poppulse and another Tripath Amp from Silverstone (Model EB02).

I have the possibility to hear with several speakers and I found something interesting:
Beside the two Tripath I own a very potencial and well known Power Amp from older days - the Exposure Super 8 - one of the better and expensive ones of class A/B. Following Speaker - Amp Combination was tested by me:


B & W Preference 6 with Exposure >>> Too much bass full filled in room - I thought the Exposure was raping the speakers . It might also depend on the B & Ws because much speakers of this brand are well known for their pronounced upper bass. Not a good combination - IMO

Allison Al-105 with Exposure >>> Great Combination - well balanced in all frequencies. Super rhythmic sound. Here you could really enjoy the quality of exposure

Allison Al-105 with Poppulse >>> a slight flat - but a quick and a good kick bass. Soundstage is wide and Mids are present.

Allison Al-105 with Silverstone>>> after played warm the soundstage was a bit more detailed and full compared to combination above. Mellow but a bit soft bass. I prefered this combination especially on lower volume. Great and colourful detailed mids.
But the Silverstone is limited in power compared to Poppulse.

Allison CD 6 with Poppulse Great combination. Full , colourful sound. Well balanced.

JmLab Profil 77 with Poppulse Also fine combination and better than with the Al-105. Not a slight flat bass like with the Al-105.


I wished the Silverstone (with Tripath TA2021B) had a bit more power. This amp really surprized me positiv way with the Allison Al-105.

So guys what should I say: I am full busy nowadys with Class D Amps and still looking forward to receive the next ordered Class D: Nuforce Icon (No Tripath - a different chip). Seems to be a little wonder Will report you soon ... here or in a separate thread.

 

[ChuckT]

Just discover a good tweak relating to the internal opamp of TA2022

The decoupling of the two 5V use by the internal opamp is poor. The power supply has 7815, resistor to drop voltage, ferrite, then to a 7805 that supplies both 5V for TA2022 and the digital vol chip.

My tweak is remove the 0.1uf ceramic next to 7805 and next to 5V pins. And directly put a small cap on each of the two 5V pins.
I use the Blackgate hi-q 47uf/6.3V and the result is better bass and better mid. Need to burn in for long time.

 

[Quantom]

Just curious. On the stock PopPulse (yes I really mean stock, haha), does anyone get a trace of static after the unit warms up and "clicks" into activation? I get hissing on my model, and I'm wondering if anyone has a clue how to resolve it. It shouldn't be a power problem, as I've tried a few power points and they all seem to have the same issue.