High gain opamp based preamp for low output MC cartridges

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It's strange how different forums favor different phono pre's. DIYAudio is all over the Peal2, A/K is all over the AD797 & Wayne's version & Lenco Heaven the EAR834. And the different sites members cannot for some reason be incised to consider the others!!

Cheers
I will regard Nelson Pass's PEARL 2 and Wayne Palmer's opamp based design of a different level of complexity and performance.

Wayne Palmer's LT1115 based design is much easier to implement and almost a guaranteed success for most DIYer's. The topology of passive-active RIAA is a well documented approach.

The Pearl 2 is much more expensive to implement and a real technical challenge in device (input transistors) selection. It is not particularly difficult, but is at a higher level of technical chellenge.
 
That's funny I designed the AD797 and I have yet to listen to it as a phono pre-amp.

Hi Scott, this is Wyn. I'm currently listening to it and the LT1115 in dueling phono stages versus my normal tube preamp.
I did this as it seemed like an interesting project that could be managed by many of the AK users and I had received requests from several people to produce an "improved" version versus some of the previously posted designs based on comments I had posted.
I approached this as a standard engineering design- the best trade off in noise, distortion and overload margin that I could achieve with a variety of options available to the interested builder, and ability to provide consistent performance with pretty well any kind of power supply.
It was a couple of weeks of entertainment in my retirement- which is always welcome.
It's also presented me with the opportunity to do detailed comparisons between it and the tube amp and try to assign reasons for the audible differences despite the obvious technical and measurement superiority of the opamp design.
 
I will regard Nelson Pass's PEARL 2 and Wayne Palmer's opamp based design of a different level of complexity and performance.

Wayne Palmer's LT1115 based design is much easier to implement and almost a guaranteed success for most DIYer's. The topology of passive-active RIAA is a well documented approach.

The Pearl 2 is much more expensive to implement and a real technical challenge in device (input transistors) selection. It is not particularly difficult, but is at a higher level of technical chellenge.

Hi it's Wyn not Way or Wayne.
For your information. ADI fellow like Scott- from 1991, Senior Fellow from 1998, so Scott and I go a long way back...
 
I will regard Nelson Pass's PEARL 2 and Wayne Palmer's opamp based design of a different level of complexity and performance.

Wayne Palmer's LT1115 based design is much easier to implement and almost a guaranteed success for most DIYer's. The topology of passive-active RIAA is a well documented approach.

The Pearl 2 is much more expensive to implement and a real technical challenge in device (input transistors) selection. It is not particularly difficult, but is at a higher level of technical chellenge.

By the way, it's not a traditional passive- active design. It's essentially active, with a passive continuation of the 75us TC in the input stage to improve out of band overload characteristics.
It was indeed intended to be as DIY friendly as possible for the AK community. However it measures quite well in the normal parameters of distortion, RIAA compliance, noise, overload capability, supply immunity and load drive capability.
 
By the way, it's not a traditional passive- active design. It's essentially active, with a passive continuation of the 75us TC in the input stage to improve out of band overload characteristics.
It was indeed intended to be as DIY friendly as possible for the AK community. However it measures quite well in the normal parameters of distortion, RIAA compliance, noise, overload capability, supply immunity and load drive capability.

Wyn, sorry about mistaking your name! :eek: I really appreciate what you do for the DIY community. I am a solid state guy and am eagerly waiting to build your design.

My previous 2 preamp are both commercial products: The Kenwood Basic C2 and the Harman Kardon AP2500. After I retired, I want to go back to more home built gears. I have follow the DIY phono stage design here and at AK. Your approach addressed the essential issues without compromise in performance and builder friendliness.
 
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It's strange how different forums favor different phono pre's. DIYAudio is all over the Peal2,
Cheers


Given the vast range of phono pre's that have been posted on here, measured and built I can only assume you actually mean 'recommended for a first build with full hot and cold running support'?


Having done support for DIY builds on a non-audio group I have great admiration for those who put the time in to help out and get people on the first wrung of a hobby, but I think it misses out the breadth of choice you have on here for phono designs, even wider if you are willing to pay a few euros for some of the linear Audio articles. You can literally pick your poison!
 
Doing the support is not a problem. I specifically did this for AK not DIY audio, and in particular because several people were asking me to, and I did it with some reluctance. It's essentially a turnkey solution with only a bit of soldering required, and one with quite good objective performance which is backed up with simulations and measurements.
It has real, simulatable LT spice schematics (with the selected opamp macros) that actually converge, KiCAD files, Mouser component lists, and even a recommended case etc. It even has a pretty accurate lumped component model for the Miyajima Madake cartridge so you can explore the effect of loading etc.
The models are not device level, but it might be a bit tough acquiring a full model/simulation environment from ADI and TI.
Nevertheless, I didn't post this on DIY Audio because of all the factors you cite, although it might be interesting to see how the measured performances of the other solutions compare...
 
Doing the support is not a problem. I specifically did this for AK not DIY audio, and in particular because several people were asking me to, and I did it with some reluctance.

What Bill does not mention is that there are several threads here running for years with probably more fundamental information on obscure issues with phono reproduction along with much debunking of common folklore than appear anywhere else.

We tried to get a group buy started to to have a test LP produced but it seems stalled due to several issues. Under scrutiny some of the most trusted test LP's are seriously flawed on some of their tracks.

In general I'm in with the Pass Labs folks, more fun. Totally happy with this running off of Jan Didden's silent switcher.

A simplified universal differential or single ended phono preamp

BTW saw John Leverault a while ago.
 
That's funny I designed the AD797 and I have yet to listen to it as a phono pre-amp.


One of the greatly missed bcarso's last posts was about a phono stage he was working on. JFET input follower, with another as current source IIRC, feeding an inverting AD797 with all RIAA in its feedback network. Sounds like a pretty good plan to me; next in the project line.


All good fortune,
Chris
 
One of the greatly missed bcarso's last posts was about a phono stage he was working on. JFET input follower, with another as current source IIRC, feeding an inverting AD797 with all RIAA in its feedback network. Sounds like a pretty good plan to me; next in the project line.

Brad was a good guy, the buffering also eliminates the current noise problem with MM and the inverting connection eliminates a couple of other issues with the "all-in-one" RIAA.
 
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What Bill does not mention is that there are several threads here running for years with probably more fundamental information on obscure issues with phono reproduction along with much debunking of common folklore than appear anywhere else.

We tried to get a group buy started to to have a test LP produced but it seems stalled due to several issues. Under scrutiny some of the most trusted test LP's are seriously flawed on some of their tracks.


I've been looking for online courses on advanced cat herding but can't find anything so gone to soldering so I can at least start trying to measure something. All good fun and lots learned but defiantly into 'advanced electron herding' on some of those threads :)
 
The Madake/interconnect cable is c.16.4ohms DC. The combo also has a 10.7u series L with a parallel 60 ohm R, followed by a 1.1u series L.
It also has a pretty complex cantilever resonance model (third order) and a tone arm resonance (second order) model.
All of the models were fitted to measured behavior and as a check I varied the RC load and measured the frequency response- with acceptable agreement between the model and measured result, particularly since the two copies of the cartridge that I have measure a bit differently.
I was also able to use the models to fit a PEQ to the response and reduce the overall measured frequency response flatness to better than +/-1dB 20kHz-18kHz, which is much tighter than the original.
I would say that the modelling exercise was acceptably successful.
Of course, this all depends on how accurate the test records that I used were.
 
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