Cole lcr phono stage rebuild

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Nick
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#46 Re: Cole lcr phono stage rebuild

Post by Nick »

17th March 2009 - First post (three of us look at it and say that’s a bit crap)
1st February 2014 - New circuit published fixing some of the problems, but still a bit naff

So after 5 years and 1500 posts some of the changes that we would have made in the first place are made. Its not having a go at you Ray, but I am with Mark about diyAudio in general. I get the feeling that he likes the circuit shape, and is pushing that because he likes the shape. He is clearly not a valve guy (and says so) as he thinks at first 0.2% distortion is ok (bet it will be much worst at 10kHz).

IMHO, "highly regarded" counts for nothing if its not been heard first hand by someone whose ears at least I have some calibration data for. By that I would mean either have listened at the same time to stuff as me and I agree with (or at least understand) their view, or have listen to stuff that I have listened to and I agree. Doesn't mean I am right, but it at least means that I have a view about what its likely I will think about it which is all I care about.

Other than that, its just words on the internet.
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Ray P
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#47 Re: Cole lcr phono stage rebuild

Post by Ray P »

Nick, no problem - as I said, I have no horse in this race and was simply trying to make a helpful suggestion along the lines of what I perceive to be Steve's requirements. Perhaps I made a mistake in originally linking to the first post rather than the revised version, I was aware of the positive developments later in the thread and it was that version I was suggesting as a possibility.

You are much better equipped than I to make an objective assessment of a circuit, that's fine and I respect and appreciate the information you impart so openly, however, it's complicated because I 'know' some of the DIY Audio posters who've made positive comments and, based on correlation with other projects, I respect their subjective opinions? I also recognise that you need to be selective when reading DIY Audio and in that respect it is just a resource that's available to us but it's also important to remember we're not all heading to the same destination.

Can I suggest that a more constructive response would have been to make some observations and, on that basis, offer a meaningful alternative.

As Steve might say, 'I'll get my coat'...
Sorry, I couldn't resist!
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Nick
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#48 Re: Cole lcr phono stage rebuild

Post by Nick »

You can suggest that yes.
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IslandPink
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#49 Re: Cole lcr phono stage rebuild

Post by IslandPink »

Maybe I should have said that we've had at least two threads about suggestions for good simple phono stages to build. I will try and dig out one, I think we were advising Thomas at that time.
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#50 Re: Cole lcr phono stage rebuild

Post by IslandPink »

Somebody asked about this subject recently -
https://www.audio-talk.co.uk/phpBB3/vie ... =11&t=6545
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#51 Re: Cole lcr phono stage rebuild

Post by Ant »

5 years ago almost to the day......
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#52 Re: Cole lcr phono stage rebuild

Post by Ant »

Did a little bit of work on the cole this morning

As there are 2 redundant sockets on it for the blown mc input i wired them up to the mm/mc switch on the back to give it 2 mm inputs instead.
Interestingly there is 33k on the original mm inputs, didnt have any of those, but i eventually found some 47k ones for the second input
The circuit shows 50k on in the input, so why there is 33k in there i dont know
Maybe that lower loading wasnt ideal for the carts mi dad was using with it

There is alot said on T'internet about mc loading, not so much about mm loading.

A quick look at an online load resistor calculator for the vm760slc based on its stated inductance, and an assumed 200pf of capacitance spits out a figure of 46k, however drop the capacitance to 100pf and it comes out at 68k

The cole doesnt have any caps on its input, im not sure wether the miller capacitance of the input valve will have a bearing on the filter variables.

The dynavector paperwork doesnt state a figure for its inductance, it just says the load should be greater than 1k...

Hmm
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#53 Re: Cole lcr phono stage rebuild

Post by Ant »

Well ive come to a perhaps odd decision to take the cole back out and put the benedict audio back in.

The cole, quite frankly is pissing me off. Because it is inconsistent in how it sounds.
Play something like zakhir hussain and its wonderful, really really lovely, but put something else on thats abit more complicated and it goes kind of polite and the edges of everything get abit fuzzy for want of a better word, and the bass gets a little wooly for my tastes.
Theres no kick up the arse that some stuff needs to have

It all gets a gnats out of focus, wheras the benedict audio is consistent. It does the same thing with whatever you play.

Its not as good as the cole for zakhir hussain, but i prefer it for led zep or cowboy bebop or joe bonamassa.

This didn't show up until i listened to it for a couple of days. Its annoying that it can be either spectacular or abit mediocre depending on what you play through it
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izzy wizzy
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#54 Re: Cole lcr phono stage rebuild

Post by izzy wizzy »

I always wondered how the first stage had enough drive for the LCR EQ. Even if was much higher Z, they can be problematic too in keeping stable values with level. Maybe either or both issues are what you hear.
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#55 Re: Cole lcr phono stage rebuild

Post by Nick »

Even if was much higher Z
Its not, its a 600R network.
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#56 Re: Cole lcr phono stage rebuild

Post by izzy wizzy »

Nick wrote: Wed Aug 25, 2021 9:45 pm
Even if was much higher Z
Its not, its a 600R network.
Blimey. Poor little 1st stage trying to drive that. Unless I'm missing something.
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#57 Re: Cole lcr phono stage rebuild

Post by Ant »

Been faffing again, i decided to put the vm760slc in the unipivot instead of the dynavector to see if the cart was part of what im hearing with it.
Turns out it was
Not all of it, but some of it.
The dv is sounding abit tired which is exacerbating the slight lack of focus
The 760 is more focused and has better leading edge definition.
It seems to match the cole better than the dv does, its characteristics somewhat counterbalancing the cole.

Still abit polite though
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#58 Re: Cole lcr phono stage rebuild

Post by Thermionic Idler »

I dropped by and had a listen to Ant's Cole whilst I was up north yesterday having my Garrard serviced. The midrange clarity and realism was really quite eerie - of course the rest of the system is entirely different to mine so how much of that was down to the phonostage is tricky to say, but very impressive nonetheless. Very good with classical, which of course forms a lot of my listening.

I need to get on the case with my Millett LR stage but that's for another thread.
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Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
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#59 Re: Cole lcr phono stage rebuild

Post by Ant »

It was nice to see you dave, one heck of a drive to get the 301 looked at!

Re the cole, yes it was doing its 'thing' with the heifetz tracks and the peter gabriel, but as you say, unravelling what bit is doing what is an impossible task. As a whole everything plays its part, and im quite glad you liked the system as a whole

Some of the things you mentioned i think come from the work on the arm, some from the phono stage, and i know which bits have affected what. So the phrase musically communicative was a nice one to hear

I think the pete millet stage could be better than the cole is overall, especially the way you intend to implement it
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