https://rpaudio.estranky.sk/fotoalbum/mbl-6010-preamplifier/
Fantastic preamplifier. Excellent sound. With LM6171
Fantastic preamplifier. Excellent sound. With LM6171
That's a difficult call to make because different ohmmeters will source different tests currents, and since junctions of transistors, rather than just resistances are involved, voltage drops will vary in a nonlinear fashion with applied test current. That will make for unpredictable and different readings amongst the different meters used to make them.
@kozard @egellings
There is no need to worry about AD797. I have tried both assembled and Chinese bare boards populated by original ICs, I also have tried swapping the ICs. No difference at all.
There is somewhere in this thread a post by @scott wurcer, a member with first hand knowledge, who knows that AD797 has some features that can't be replaced with some other rebranded IC..
This board seems to be generic but good design that boasts with the 'stolen' famous name. However, very good indeed. I'm not impressed by trade marks but measurements.
There is no need to worry about AD797. I have tried both assembled and Chinese bare boards populated by original ICs, I also have tried swapping the ICs. No difference at all.
There is somewhere in this thread a post by @scott wurcer, a member with first hand knowledge, who knows that AD797 has some features that can't be replaced with some other rebranded IC..
This board seems to be generic but good design that boasts with the 'stolen' famous name. However, very good indeed. I'm not impressed by trade marks but measurements.
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If you are looking at building a fantastic op-amp based preamp you should seriously consider the Douglas Self Preamp that you can find right here in DIYA. I would argue SOTA still to this day. You can end up with something that could be sold on the market for thousands. Boards, enclosures, Front and Back panels all exist for it
Dennis Colin wrote an article in a construction-oriented audio magazine similar to The Audio Amateur, if not that magazine, about a phono stage he designed called the LP-797. It used a very low noise dual JFET with both transistors paralleled (LSK489 or some similar type-number; don't remember exactly) bootstrapped by an AD797 to remove miller effect and to linearize its performance. That stage implemented the HF roll-off of the RIAA curve passively. This drove another AD797 set up as a straight gain stage with a switch to select one of 3 possible gains, and that stage drove another AD797 that implemented the bass boost using feedback. I built one and can say that it is accurate as far as EQ conformance goes (better than 0.5dB everywhere), is dead silent, and it's just not there; you hear just the music, without a trace of the preamp's presence. Highly recommended!
if i am not wrong the 6010d is a line stage only ?
If i understand well the design is like this input buffer stage > volume pot > output stage ?
i wonder how much buffering the inputs is important Has anyone tried to by-pass them ?
many great line stages do not buffer the inputs before the volume control
are any measurements available ?
If i understand well the design is like this input buffer stage > volume pot > output stage ?
i wonder how much buffering the inputs is important Has anyone tried to by-pass them ?
many great line stages do not buffer the inputs before the volume control
are any measurements available ?
I used an AD797 for the main line level gain stage in this preamp
https://www.ovationhifidelity.com/product/model-1501/
I can attest to it being a fantastic opamp and good reason for it to be found in some of the best gear around.
(Despite ppm level distortion spec’d and ultra low noise, it didn’t stop a tube loving reviewer from asking me ‘did you use an opamp?’. I replied ‘yes, an AD797’ hoping he’d recognize the value in that, but instead he replied ‘I thought you did. I couldn’t help but hear the opamp haze that veiled the music’. They had already opened the preamp up to photograph the innards 🤦♂️. Utter rubbish and why I especially dislike the British hifi press - self-annointed money grubbing charlatans End of rant. )
https://www.ovationhifidelity.com/product/model-1501/
I can attest to it being a fantastic opamp and good reason for it to be found in some of the best gear around.
(Despite ppm level distortion spec’d and ultra low noise, it didn’t stop a tube loving reviewer from asking me ‘did you use an opamp?’. I replied ‘yes, an AD797’ hoping he’d recognize the value in that, but instead he replied ‘I thought you did. I couldn’t help but hear the opamp haze that veiled the music’. They had already opened the preamp up to photograph the innards 🤦♂️. Utter rubbish and why I especially dislike the British hifi press - self-annointed money grubbing charlatans End of rant. )
I should clarify the statement above. This is what he said to me in our email correspondence- the printed review was quite complimentary.
Is was an LSK389. I used a similar scheme with the JFETs in this preamp (links will take you to the audioXpress article)
https://hifisonix.com/projects/x-altra-phono-eq-preamp/
Here you go Berlusconi
https://www.diyaudio.com/community/threads/doug-self-preamp-from-linear-audio-5.280458/
https://www.diyaudio.com/community/threads/doug-self-preamp-from-linear-audio-5.280458/
hi has anyone tried without buffering the inputs ? is input signals buffering before the volume controlreally essential for best performance ?
these input buffers complicate the design There must be a good reason for using them
thank you
these input buffers complicate the design There must be a good reason for using them
thank you
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It depends on the source impedance of the input signal and the load impedance (resistance) of the volume control. If the input signal's source impedance is low enough and the control's resistance is high enough such that the source is not loaded down or its distortion level increased, then buffering would not be needed. A 1 to 10 or more ratio seems like a reasonable amount to me.
Thank you very much for your very valuable advice This should mean that when using a 10kohm pot the source impedance should be 1kohm or lower
Very common with usual dacs without tube output
Very common with usual dacs without tube output
I bought one of these 6010D Clones and it sound good but I already changed the input buffer JRC5534 IC's to LME49720's and that helped out the SQ, less edge.
I want to change the other four JRC5534's with the AD797. I saw in a Japanese website that they recommended replacing only these middle gain stage four JRC5534's with the AD797. That website had a schematic of the clone I have which shows the input buffer JRC5532, the Middle stage with JRC5534, and output buffer stage with JRC5534's. So I will order 5 AD797's for this middle gain stage and may use either the OPA1641 or OPA134 on that last output buffer stage.
I have already ordered better caps from EPCOS and Vishay/BC components for the power supply and decoupling caps.
I want to change the other four JRC5534's with the AD797. I saw in a Japanese website that they recommended replacing only these middle gain stage four JRC5534's with the AD797. That website had a schematic of the clone I have which shows the input buffer JRC5532, the Middle stage with JRC5534, and output buffer stage with JRC5534's. So I will order 5 AD797's for this middle gain stage and may use either the OPA1641 or OPA134 on that last output buffer stage.
I have already ordered better caps from EPCOS and Vishay/BC components for the power supply and decoupling caps.
Last week I installed the EPCOS Power supply caps and the BC Components/Vishay 3300uF caps along with the 47uF caps. These upgrades with the other LME 49720 have taken this pretty nice sounding preamp to a whole different level. First thing was the music is now coming from a very quiet background that I now can hear deeper into the recordings that previously with this preamp. It now has a wider soundstage and deeper soundstage than before. I have the AD847 opamps but haven't installed them yet because I wanted to hear what the preamp sounds like after the capacitor upgrades. The caps the preamp came with are not very good and the Elna S I guess for the Stargate series were a totally different color from what I had in my Electrocompaniet ECP-1Phono preamp which were blue, these are like a dark violet color. So I knew those would not stay and from what I understand those "Stargate" series caps were discontinued a long time ago and really were not that good to begin with.
I did notice some channel balance issues and now that I changed the caps that seems to have gone away. I will measure the caps that came out and see what they measure. Those Nover PS caps were ok but the EPCOS were way better.
I will change out the NE5332 in the gain stage with the AD847's and see how that turns out before going to the last Buffer stage. I wanted to install the LME49710's in the rest of the circuits but only seem to available from Chinese sellers on ebay, so I didn't want to buy any fakes and when I asked one the seller's where he got them from he ignored my question two times so that was a RED flag which led me to buying the AD847's. If those don't work out I will go with the OPA827's which are supposed to be the newer version of the OPA627's.
I did notice some channel balance issues and now that I changed the caps that seems to have gone away. I will measure the caps that came out and see what they measure. Those Nover PS caps were ok but the EPCOS were way better.
I will change out the NE5332 in the gain stage with the AD847's and see how that turns out before going to the last Buffer stage. I wanted to install the LME49710's in the rest of the circuits but only seem to available from Chinese sellers on ebay, so I didn't want to buy any fakes and when I asked one the seller's where he got them from he ignored my question two times so that was a RED flag which led me to buying the AD847's. If those don't work out I will go with the OPA827's which are supposed to be the newer version of the OPA627's.
hi thanks a lot for the sharing of very interesting findings
just a word about the channel unbalance as the gain is set by resistors normally the usual sucspects is the volume pot
this is at least my experience with cheap preamps The pot is not their strongest point for sure
i heard of some fake Alps blue I really do not know how to spot them from the originals
also caps could be fake Better buy strategic parts from reputable sources
Of course this will have an impact on the final cost
i am a little confused If i understand well the block schema is input buffer > volume pot > gain stage ?
now you current and best configuration is LME 49720 > volume pot > AD797 ?