i have opened an Alps Blue Velvet What leaves me puzzled is that the resistive traces are layered on a plastic film that could warp
I would prefer the solution used in cermet pots Unfotunately they usually come linear and single
I do not know about their noise
I would prefer the solution used in cermet pots Unfotunately they usually come linear and single
I do not know about their noise
hi thank you very much for your kind and valuable advice
I will use the pot just to set the volume once at the beginning I have notice some things
When there is the need to act on the pot there is something wrong with the sound
The sound must be complete even at low volume If there is the need to increase the volume there is something wrong with the sound
I am a little worried about the quality of the contact between the wiper and the resistive trace
If i understand well in a cermet pot the resistive trace is deposited on a ceramic substrate ?
i do not know if there is a way to check for the contact quality
A mechanism of a stepped attenuator should provide a great contact quality
This issue is a little overlooked
I remember cleaning some rcas on equipment using a stain remover with great results
I have also read about faking a linear pot to log It could work I have to try
Hi Ginetto,
Today I have performed some quick measurements, just to see what I have, and its not that bad. I have used Arta with Xonar U7 MKII sound card which has some limitations. The real results should be even better: I should have used a better signal generator and better wiring, but anyway.
Measurement results are presented on two screenshots shown below.
The first snapshot presents FFT measurements at at 500mVRMS (1.41 mvp-p). The resulting THD+N is 0.0015%
The first snapshot presents FFT measurements at at 900mVRMS (2.54 mvp-p). The resulting THD+N is 0.0054%
(Right now I've noticed how old is this thread, but never mind)
Attachments
Hi ! thanks a lot for the very interesting results Do you have a spectrum of the test signal as well maybe ?
i guess it would be important to check the signal generator contribute to THD and noise ?
i would love to start some measurements myself and it seems that to get a low THD and noise signal generator not too expensive is a challenge
The original has great measurements indeed
https://www.stereophile.com/content/mbl-6010-d-preamplifier-measurements
i guess it would be important to check the signal generator contribute to THD and noise ?
i would love to start some measurements myself and it seems that to get a low THD and noise signal generator not too expensive is a challenge
The original has great measurements indeed
https://www.stereophile.com/content/mbl-6010-d-preamplifier-measurements
Hi @ginetto61
Exactly my thoughts. Yesterday I have realized that batteries in my Akitika sinewave generator have run out a bit so I have used Xonar U7 output instead. I was too late to purchase batteries on Saturday. Therefore I have emphasized that the measurement conditions weren't quite right.
I will repeat measurements in better conditions and report. However, if you go back to that article you've reffered to, you may see that my measurements are close to the published. Of course, this "clone" is a copy just in name, and yet it is great. Meanwhile I've built a great DAC and use it along with this preamp. They're great companions, a great siglal source. I don't use commercial devices for this purpose.
Ti saluto!
Exactly my thoughts. Yesterday I have realized that batteries in my Akitika sinewave generator have run out a bit so I have used Xonar U7 output instead. I was too late to purchase batteries on Saturday. Therefore I have emphasized that the measurement conditions weren't quite right.
I will repeat measurements in better conditions and report. However, if you go back to that article you've reffered to, you may see that my measurements are close to the published. Of course, this "clone" is a copy just in name, and yet it is great. Meanwhile I've built a great DAC and use it along with this preamp. They're great companions, a great siglal source. I don't use commercial devices for this purpose.
Ti saluto!
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Hi thank you very much again Great preamp indeed I have used Arta in the past with a Tascam uh-7000 usb interface
It had some noise issues due to the stock smps A cheap Sony 12V smps cured that I did not check the distortion at the time
It is a pity that the signal generator side of these cards is so poor I would love to get a qa403 spectrum analyzer one day
Buona serata 😉
It had some noise issues due to the stock smps A cheap Sony 12V smps cured that I did not check the distortion at the time
It is a pity that the signal generator side of these cards is so poor I would love to get a qa403 spectrum analyzer one day
Buona serata 😉
I have now had the 6010D clone a few months and I have upgraded the power supply caps from stock to better caps (EPOCOS and BC Component) all the way to the op-amps. I also have upgraded the JRC 5534's and 5532's with LME49720's and AD847's. These simple upgrades really made this a wonderful sounding preamp from stock. Even though this is not an exact copy of the 6010D preamp, it is a very nice preamp once better components have been added. One thing that stood out was that the music is coming from a more quiet background. I still want to change out that Volume control and put a TKD in there but can't see the value of the pot. I may have to remove it to see or measure it. The one channel is a little lower than the other, so that may be due to the pot. I have to run a signal through it and measure with a scope to make sure its the pot and not something else. Other than that I have no complaints and is a good match with the Hypex Nilai Mono blocks I recently built.
Hi Ginetto and Drummerboy!
I have got today new batteries for the sine wave generator and made several measurements. Here are several results, all at 900 mVRMS output (2.54V p-p). Results at lower output voltage are better but I wanted to show the worst case, which isn't that bad at all!
I have also much better sinewave source, a great DAC based on Xingcore digital interface, but it appears that the soundcard is limiting further measurement improvement. But I'm happy with the presented results.
First, sound card loopback, output 300 mVRMS, alone:
Now, Akitika sinewave generator at 300 mVRMS output, alone:
Now, Akitika (300mVRMS) into 6010D, output 900 mVRMS
Finally, Xonar U7 MKII (300 mVRMS) into 6010D, output 900 mVRMS:
I have got today new batteries for the sine wave generator and made several measurements. Here are several results, all at 900 mVRMS output (2.54V p-p). Results at lower output voltage are better but I wanted to show the worst case, which isn't that bad at all!
I have also much better sinewave source, a great DAC based on Xingcore digital interface, but it appears that the soundcard is limiting further measurement improvement. But I'm happy with the presented results.
First, sound card loopback, output 300 mVRMS, alone:
Now, Akitika sinewave generator at 300 mVRMS output, alone:
Now, Akitika (300mVRMS) into 6010D, output 900 mVRMS
Finally, Xonar U7 MKII (300 mVRMS) into 6010D, output 900 mVRMS:
Hi,
One of my 6010D preamps was purchased as assembled product from Weiliang. I have also assembled another from bare board and components from Farnell (UK). i have all components to build yet another preamp. Both preamps had identical measurements. ICs in Weiliang product were genuine as I have later verified. If you go back and read this thread, there is informations that it is imposible to disguise another IC for AD797.
One of my 6010D preamps was purchased as assembled product from Weiliang. I have also assembled another from bare board and components from Farnell (UK). i have all components to build yet another preamp. Both preamps had identical measurements. ICs in Weiliang product were genuine as I have later verified. If you go back and read this thread, there is informations that it is imposible to disguise another IC for AD797.
You've probably never used an Alps RK50 🤣
I agree with you on the TKD >> than Alps RK27
I wanted to originally put in the AD797 but the guy I bought it from said not to used them in that unit. That's why I went for the AD847's in the gain stage. I may still try this later down the road but as of right now this preamp is sounding really nice.
Hey Pars, good to see you over here!
You are correct, I have never tried the Alps RK50, not even heard one. It better be nice for going for $500+ at ebay, I'm sure its a great sounding pot but is it $400 better sounding than the TKD 2CP-2511? I would even love to try one of the GOLDPOINT stepped attenuator but I doubt it will fit, for this slim preamp the TKD will be good enough. Also, I have heard some good things about the Eizz pots but those are too big too.
You are correct, I have never tried the Alps RK50, not even heard one. It better be nice for going for $500+ at ebay, I'm sure its a great sounding pot but is it $400 better sounding than the TKD 2CP-2511? I would even love to try one of the GOLDPOINT stepped attenuator but I doubt it will fit, for this slim preamp the TKD will be good enough. Also, I have heard some good things about the Eizz pots but those are too big too.
Hi thank you very much for kindly sharing your excellent test results
When a preamp adds nothing in terms of THD and noise to the testing signal it means that it is just completely true to the source
This is what high fidelity is about great performance indeed
To be perfectly honest i think i have somewhere a cheap SMSL VMV VA1 this one here
https://www.kits-a.com/2013/09/21/vmv-va-1-headphone-amp/
it is designed in a similar way with opamps buffering the inputs followed by opamps driving the outputs
Unfortunately the part numbers are erased
I do not know which pot is used in the MBL clone but if it is a 10khom piece maybe the input opamps could be vene bypassed ?
That would leave a pot followed by the output stage
i would not let the case size to stop me If the circuits are so good a new bigger case could be the best solution
The original MBL preamp is 21 x 9 x 14 inch big A very sumptuos preamp indeed It inspires greatness
I already have a chassis that all these PCB's plus a large VC would fit in but that is for my all out EAR 834P clone build. The TKD will be good enough for me and will fit in the chassis I have now. If I was to get a bigger chassis I would then just go with the Glassware Dual Mono Stepped Attenuator.
Ok, today I finally got the chance to open my MBL 6010D Clone with the BZ6010D-MKII pcb in it. Since I'm not getting any help from the person I bought it from or others that are selling these clones, I had to open mine again. My Clone has a 100K Volume pot in it, it says on the part and even on the PCB. From what little I have seen on schematics of these clones there was 10K - 50K Volume pots. I do have a couple of the OG TKD Volume pots from back in the early 2000's that I had bought for my Counterpoint upgrades that I can you in here. This should take this nice sounding preamp to another level that what its at now after the power supply caps and IC's upgrades. I found out long ago that VC play a very big roll on upgrading the preamps, nothing like a very good VC to help make a preamp sound its best!