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Old 2nd November 2013, 05:08 PM   #1
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Join Date: Jan 2011
Location: Lower Mainland
Default Topping TP60 Volume Bypassed

Hi All,

For some time I've wanted to play with TP60 so I ordered one a while ago. Always wanted to bypass the volume control and have it as a stand alone amp cause I'm too lazy to get off the couch to turn the volume up and down.

Anyways, ordered the Tortuga LDR3x for remote control volume control and thought I'd give the old LDR a try.

Took out the TP60 Pot using soldering iron and solder sucker. Took out the relay and jumpered the pins on the relay and pot. Signal now goes straight to input caps.

The setup works! I'll save the impressions for later but if anyone wants to know if this setup is compatible, it is! Wow, first time I've run a low power amp on my pro woofer, compression drive home brews with reasonable gain stages on equipment. A few watts goes a long long way.

Side note, not sure how well the tracking between channels on the ALPS are suppose to be, but mine were out quit a bit.

Cheers
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Old 7th March 2014, 01:51 PM   #2
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Join Date: Sep 2010
Hello mike,
I intend to do the exact same thing (bypassing the volume pot), but when I read your post, you got me thinking about what you said about the relay. I can't figure out where it comes into play in this case. Can you please enlighten me?
Did you finish your mod? How does it sound?
Thanks!
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Old 10th March 2014, 03:21 PM   #3
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I am looking to do the same on my tp20 can u please share some pics and the question about relay?
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Old 10th March 2014, 03:26 PM   #4
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Oh yeah, I would love to hear more about Mike's experience with this, and to see some pics too.
I'll PM him just to make sure he sees this.
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Old 10th March 2014, 07:04 PM   #5
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Hi All,
My topping TP60 has 2 inputs, so the board has a relay that selects which input is plumbed into the amplifier. I don't believe the TP20 has 2 inputs, only the one so you probably don't have to bypass the relay in that one.

The TP60 takes both inputs from the back RCA jacks and both pairs go to a relay. The relay looks to be reasonable quality though. From the relay it goes to the front panel POT. Nothing wrong with the pot and the pot seems reasonably quite but when I measured the resistance dividers, they were out a bit so channel balance was out slightly.

After the pot, the signals go through the required DC blocking caps (the cap is required by the tripath chip to function properly).

I left the stock caps in but was toying with the idea of trying different ones. I'm away from home right now but can put pics of the board mods up later.

Cheers
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Old 10th March 2014, 07:16 PM   #6
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Join Date: Jan 2011
Location: Lower Mainland
Regarding the sound. I liked the TP60 presentation before the mods but I found my entire system went up a notch when a few things were fixed.

1. The gain stage between my DAC (XDA-1 fire sale) and AVR was not correct. I digitally attenuated the source(PC TOSLINK) too much before going to the DAC. I wanted to avoid clipping but went too far. I finally measured the output as the spec sheet said "1V RMS nominal". Not sure if that meant MAX or not. That said the output of the XDA-1 vs my PC sound card (Essence ST) were different. XDA-1 was slightly higher. Too high for the miniDSP 2VRMS MAX input setting. After fixing this, sound quality went up a lot.

2. Used the Tortuga board as the volume control. This forced me to mod the Topping TP60 to by-pass the onboard POT. Decided to bybass the relay too. The tortuga board has 3 input select lines so not need to use the topping as selectors. Also the remote feature is nice, now have remote control for the topping.

3. Figured out how to get ASIO from the output of the PC toslink to DAC.

I kindof did all of the above at once so there so its hard to say which was the biggest improvement. One thing to note is if you don't have a way to balance the left and right speaker amplitudes, they will possibly be out of balance when using the Topping ALPS pot.

Cheers

Last edited by mikealanlee; 10th March 2014 at 07:19 PM.
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Old 10th March 2014, 07:26 PM   #7
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Join Date: Sep 2010
Thank you so much, Mike.
Now I know what you mean by bypassing the relay.
The L/R balance is not so good indeed.
Yes, The pics would be greatly appreciated (TP-60 mod), as I am about to do the same thing to mine.
I hope you have the time to post them.
Thansk again!
Gg
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Old 10th March 2014, 08:20 PM   #8
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Location: Lower Mainland
Hi All,

I don't have time to post pics today but should be able to make a short write up in the next few days. I couldn't find a reasonable 'how to' guide for the TP60
on this (although I didn't look that hard).

If there is a how-to guide around here maybe someone could link the thread? I know it is not difficult as it is mostly just the POT bypass but perhaps a step-by-step could be useful.

Cheers,
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Old 10th March 2014, 09:57 PM   #9
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Thank you Mike.
I am receving the TP20 tomorrow (good ol Amazon Prime) and I will take a look and listen. If its any better than my Audiolab pre-power combo I might consider bypassing the POT and using it with my Audiolab Pre

Btw, would there be a sonic benifit in removing/bypassing the pot? Or would it be the same as setting the pot on 100%?
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Old 10th March 2014, 10:18 PM   #10
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Hi dakku,

I try and stay away from subjective assessment of things like the volume control. Some people like stepped resistors, others LDRs others op-amps. From what I've read, the jury is still out on the best one.

That said, the one concrete thing I can say is the ALPS pot that came with my TP60, was it was NOT balanced. The Left and Right channels measured differently. Can't remember by how much but was more than I was comfortable with. It made me look closer at my channel amplitudes. My room probably masks some of the differences but.........since I'm not an expert on speaker imaging and the potential problems of unbalanced stereo presentation, I could not comment on the repercussions.

If you could ensure the L/R balance of your entire system is matched I would suspect there wouldn't be much difference between the POT wide open and no pot; however, some people have better ears than me and my LDR does sound a bit different than my AVR. The LDR 'seems' a hair more detailed in the ultra extremes of the frequency bands. In a double blind test I might not be able to pick a difference between different kinds of volume control. To my ears, the differences are small at best.
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