New TK2050 board

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Try it

Thanks sendler! So you're saying that the present solution is prefarable to adding an (higher quality) stepped pot which is wired on?
I haven't listened to pots in along time. It's hard to say. It would be easy for you to try a stepped attenuator to find out. I'm not crazy about the current crop of series attenuators for technical reasons though. I haven't tried one but it seems that you are adding a lot of solder joints to the signal path. You colud actually just measure your pot at a reference listening level and then duplicate the attenuation with different values of resistors in it's place on another amp in order to compare at that fixed level.
 
Series attenuators

How about these?
* 2 pcs * of DACT Type 21 Stepped Attenuator 100K 2A3 - eBay, Integrated Amplifiers, Amplifiers, Home Audio, Electronics. (Eindtijd 18-mei-10 16:28:03 CEST)
No solder joints, 1% SMD resistors.
Only thing it might be carbon resistors though... :S
Got two of those here

Those are the series style that have become common. The signal passes through every resistor, one at a time, on it's way through. 100k is very high but you never know what something will sound like until you listen. Sound often does not follow theory. There are many trade offs.
 
Impedance

What would be the input impedance if I bypass the pot?
It would tend to be set by the gain setting divider in front of the TC2000 which forms a virtual ground in the center tap depending on what values you chose for the series resistor so probably 22k but this is virtual ground so I am not sure that it actually might measure higher. My dac chip seems to prefer an additional terminating resistor of 22k to ground on the input. You can go crazy tweaking a circuit. Everything sounds different including many things that engineer types will tell you that you can not hear. At some point you have to stop and just listen to music.
 
Best kits

Hello Scott,

Which class- d kit would you recommend as the best currently available ?...
I have only tried one class D amp and it turned out to kill the sonics of my AB amps. A TK2050 seems hard to beat for the price. I would stick with that over a 2020,2022,2024. The truepath 3020 also gets great reviews but costs more. I need 8 channels at least, maybe more if I use DVC woofers so price is somewhat under consideration.
 
I have only tried one class D amp and it turned out to kill the sonics of my AB amps. A TK2050 seems hard to beat for the price. I would stick with that over a 2020,2022,2024. The truepath 3020 also gets great reviews but costs more. I need 8 channels at least, maybe more if I use DVC woofers so price is somewhat under consideration.

Are you specifically recommending the TK 2050 kit listed here ?
 
I'm thinking of trying battery power. Would two batteries like this be ok? Can I charge them also in series with a 24V charger?

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translated specs:

Battery 12V7.0Ah/20hr
Rated Voltage: 12V
Rated Capacity (20hr): 7Ah
Dimensions: Length: 151mm Width: 66mm high: 96mm Total height: 102mm
Reference Weight: about 2.8Kg
Actual capacity of different discharge rate
20 hours rate: 7Ah
10-hour rate: 6.5Ah
5 hour rate: 5.9Ah
1 hour rate: 4.2Ah
15-minute rate: 2.9Ah
The relationship between volume and temperature (20 hour rate)
40 ℃ (104 ℉): 103%
25 ℃ (77 ℉): 100%
0 ℃ (32 ℉): 86%
-15 ℃ (5 ℉): 65%
At 25 ℃ (77 ℉) resistance when fully charged: about 22mΩ
Charging method (constant voltage)
Cycle: the maximum charge current of 1.75A
Charging voltage 14.5-15.0V/12V77 ℉ (25 ℃)
Charge temperature compensation voltage-24mV / ℃
Float: Maximum charging current 1.75A
Charging voltage 13.6-13.8V/12V77 ℉ (25 ℃)
Charge temperature compensation voltage-18mV / ℃
Apply to electronic scales, emergency lights, children's toy cars, lawn, parking locks, power systems, access control systems, uninterruptible power supplies, etc.
 
I like the sound of batteries

I like the sound of batteries at 25v. It is a little better than a Meanwell at 32v but more inconvenient and no cheaper so I am sticking with the SMPS. I don't know if the batteries will hold up as well when charging in series. Many people using lead/ gel batteries listen in series and charge in parallel due to the readily available 12v chargers.
.

I'm thinking of trying battery power. Would two batteries like this be ok? Can I charge them also in series with a 24V charger?

12V7AHµçÆ¿ 12V7AHÐîµç³Ø Ãâά»¤·§¿ØʽǦËáÐîµç³Ø-ÌÔ±¦Íø

translated specs:

Battery 12V7.0Ah/20hr
Rated Voltage: 12V
Rated Capacity (20hr): 7Ah
Dimensions: Length: 151mm Width: 66mm high: 96mm Total height: 102mm
Reference Weight: about 2.8Kg
Actual capacity of different discharge rate
20 hours rate: 7Ah
10-hour rate: 6.5Ah
5 hour rate: 5.9Ah
1 hour rate: 4.2Ah
15-minute rate: 2.9Ah
The relationship between volume and temperature (20 hour rate)
40 ℃ (104 ℉): 103%
25 ℃ (77 ℉): 100%
0 ℃ (32 ℉): 86%
-15 ℃ (5 ℉): 65%
At 25 ℃ (77 ℉) resistance when fully charged: about 22mΩ
Charging method (constant voltage)
Cycle: the maximum charge current of 1.75A
Charging voltage 14.5-15.0V/12V77 ℉ (25 ℃)
Charge temperature compensation voltage-24mV / ℃
Float: Maximum charging current 1.75A
Charging voltage 13.6-13.8V/12V77 ℉ (25 ℃)
Charge temperature compensation voltage-18mV / ℃
Apply to electronic scales, emergency lights, children's toy cars, lawn, parking locks, power systems, access control systems, uninterruptible power supplies, etc.
 
On topic:
How did you order your amp to NJ? And how much did it end up costing, all told?

Off Topic:
Many people using lead/ gel batteries listen in series and charge in parallel due to the readily available 12v chargers.
.

How is this typically set up? I've been wrestling with how to accomplish this very thing for my 6ch TK2050 HT power amp. I have the batteries, and all the 12V wall warts I could ever need.
 
I picked up two 12V7ah Panasonic "Valve regulated lead-acid batteries" yesterday and a charger (originally for electric bikes i think). I will experince more back and forth before I make any conclution about the benefits of the batteries. I also connected the DAC to the 24V batteries, and I think that made a bigger difference. I have a 707 Super USB dac, and the sound was clearer and deeper color in a way with the batteries. But, as written, I have to experience with the meanwell and the batteries to decide how big difference I can tell from the meanwell to the batteries on the 2050.
I did also change the input caps some days ago to mcap MKP, and there might have been a small change for the better, but I felt at this point my room is making it difficult to hear this subtle differences. So I put up two blankets on the wall (looks great;) and the difference was much bigger than changing the cap.

The 24V charger i got for the batteries makes a awfull loud bzzz sound. The seller checked it and said it was normal. But the sound is very annoying. What causes this sound from a charger? Anything I can do to make it better? I might look for another charger if I will continue using the batteries, but havn't seen that many 24V chargers.
I havn't much experience with batteries. When should I charge them? When there is no more sound, or when the voltage drops below a certain point?


How is this typically set up? I've been wrestling with how to accomplish this very thing for my 6ch TK2050 HT power amp. I have the batteries, and all the 12V wall warts I could ever need.

You connected them + to + and - to - for charge in paralell with 24V charger. So have to reconnect + to - for listening at 24V. I bit too much hassle for everyday use once the initual please of getting some new stuff decreases.
 
The charger will probably be putting out about 27.6V so that it is safe to use as a float charger. It is worth checking the charge voltage with a meter when it is charging the batteries. I suggest you don't let the batteries drop below 22V under load as this will reduce the battery life. I am very familiar with this size of SLA battery as I use both Panasonic and Yuasa branded ones at work as standby battery suppies.
 
The charger will probably be putting out about 27.6V so that it is safe to use as a float charger. It is worth checking the charge voltage with a meter when it is charging the batteries. I suggest you don't let the batteries drop below 22V under load as this will reduce the battery life. I am very familiar with this size of SLA battery as I use both Panasonic and Yuasa branded ones at work as standby battery suppies.

When I connected the charger I first measured around 25V. Then it was gradually increasing. After about 2 hours I measured 30V. Is that way too much?
I only charged about 2 hours today. and I measured just above 26V after deplugging the charger.
 
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