Trouble with AT VM740ML, poor fit?

Recent case of upgraditis, my Denon DL110 must be nearing end of life and looking at price of replacements decided might as well try something new and seemingly well regarded, so went with the VM740ML. Was originally running the signal through a Pioneer A30k's phono stage as previous budget preamp purchases appeared to make no discernable difference. So I also decided to get a new phono stage also, the Musical Fidelity LX2-LPS.
Initially all was great, certainly much more detail but over a few weeks and listening to different stuff I've decided there is too much treble, in some cases its almost shrieking at me it seems and now I can't bear it, seem to have lost the immersion I had with the dl110.

Looked into it some more, the AT is 4mv where the Denon is 1.6. Also reading into capacitance that could affect the sound in this way, common thought is that the MF amp is 100pf, and I measure the Rega cable and tonearm at 120pf, the AT suggests a suitable pf is 100-200, would the extra 20 make a difference in this way so is it just a poor fit?
Input sensitivity of the MF amp is 3mv, where the AT is 4mv and the Denon is 1.6mv, i think this means technically the Denon is the one that should be worse off as the amp sensitivity is a minimum requirement not max?

Anyway, I finally decided to refit the Denon and all is right with the world again.

All this most noticeable when using the cans, AKG K712 via a Graham Slee Solo headphone amp, the B&W speakers seem a lot more forgiving but I think that's due to the B&W's being a bit more of a relaxed sound anyway.

Recent weeks also saw the amp replaced with a M2si, have done various tests though bypassing the amp or reconnecting the old one and amp does not seem to be a factor.

So where next? Cut my losses and sell the VM740 and get another dl110 to replace (or upgrade to something similar in style?) or bin the MF preamp and get one more suited to the VM740? Is it likely my headphones are just too unforgiving?

Any thoughts welcome

 

One of the problems with the 4 coil AT carts is potential treble lift depending on different factors, including loading. The treble lift can be as little as +2 or as much as +5 @10kHz.

One thing you can try, which is what I use to do when I ran a 4 coil AT, is make or order some loading plugs and load down to 39K instead of the standard 47. That will shave off some of the top end and should get you closer to neutral, at least out to 15-16Khz. That's based on my measurements with a 4 coil AT, not guesswork.

I have since moved to the 2 coil AT design, which doesn't require special loading for a neutral sound. Again, based on measurements.

More info loading down here:

Parallel Resistive Loading

IIRC the MF phono preamp should have fairly low capacitance, maybe 100pf or less.

RE: your headphones:

Looking at RTings we can see they are far from 100% neutral (most headphones aren't). There is a significant dip around 5.3K and a boost around 8.7K. The later may be increasing the "brightness" a bit.

One of the reasons I dislike headphones for vinyl is if I want to keep things analog, I can't use a digital EQ program. There are analog EQ boxes for headphones available, but they won't be as complex or accurate as the digital EQ. Might be worth trying though.

 

Well, the Denon is a moving coil, and the AT is a moving magnet. Great differences in output. Both could be used with MM input, but some MCs have a high input level too. 20pf isn;t going to make any difference at all.

 

Well, I have room for that 740, in case you need to send it on its way.

M~

 

Many thanks for this, very interesting. I've refitted the 740, and have made up a couple of plugs with 220k resistors in, as the MF phono amp has loading ports, which from what I can tell is simply a linked connection to the inputs. Unless its just wishful thinking, there does appear to be a bit of a softening in the sound, and my better half who seems to better tell differences in audio believes it sounds much better. I think it will take me a bit more time living with it again to see if things are improved in general.

I'm interested in how you measured this? I did some very rough tests by means of playing a frequency sweep from a test lp and recording to the laptop - unfortunately via the onboard mic as it seems the laptops in the house all now only have 'headset' jacks rather than standard line in, but i did get a result and opened in Spek to see what it looked like, very slight differences but nothing definitive that I could tell, is there a specific method/source material you could recommend for this purpose? Obviously with my method the headphones or speakers are still part of the equation so I need to get the desktop pc setup somewhere close to get connected directly to the line out of the phono amp.

Yes I think the headphones could be a tad bright, but of the ones I've tried so far these are the best, and when the source is good they do sound fantastic, maybe I need a different set for different types of music.

 

I measured using a CBS Str 100 test record, recording rec out or preamp out into audacity (using a USB audio interface) then analyzing the WAV file in ARTA. That takes the speakers out of the equation so we are only dealing with the cart and preamp.

Yes, the MM load jacks on your MF preamp are where you want to put the loading plugs.

On a preamp without loading jacks, I use brass T-connectors.

Always turn gear off when changing loading plugs.

 

Thanks for the guidance on this. I've had a play with a couple of different tools to analyze the wav files of freq sweep and pink noise from the hifi news test LP I have, although doesn't seem too well regarded as a test source so might look out for the CBS one you mention. Need to spend some time getting my head around ARTA as had trouble getting it to analyze an existing file, might be due to using the free version, tried some others inc Abobe Audition trial with varying degrees of success, plus tried with my scope - anyway end result is I need to spend more time getting a result comparible to those you see on freq response charts on reviews etc.

That said, the results I can see do appear to suggest the treble is flattened by dropping to 39k and below, but at 15k it went too far - listening to these various values for me I find 33k to be seemingly bang on, it sounds fantastic, the sound is now far surpassing what I had from the Denon DL110 as so much extra detail and none of the shrillness I got from the AT at default 47k, I struggle to describe audio qualities sometimes but just seems so well 'rounded' and full now. Maybe the lower value seems best for me due to the sound of the headphones.

So thanks again, definitely on track now and feel I've got a good improvement from my investment, very pleased.

 

If you ever need help analyzing the WAV files you can always send them to me over PM.

Re: loading down, you can definitely take it too far which it seems like you figured out from experimenting. If the headphones lean bright, one you thing you could try is loading the cart close to flat for both speakers and headphones, then using an analog eq for the headphones. Jds labs makes one that's not too expensive IIRC.

 

I personally think with my exp is that these ATs are just too bright. No matter what I did I couldn’t get them to calm down. Not just that it doesn’t seem to be as natural sounding as my DL 110 which I still love. YMMV. But it sounds like you tamed it !! Cool. I couldn’t get my At440ml to do that. Of course the 740 has some improvements too !

 

What exactly did you do? Measurements prove that parallel resistive loading works, but most people are unwilling to do it.

 

Awesome, thanks, I'll spend a bit more time (I don't like to be defeated ) but I may well take you up on the offer.