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External phono preamps with Onkyo A-9010

mschool

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Onkyo A-9010 Amp owners: have you ever bypassed the internal phono stage and connected to one of the line inputs with an EXTERNAL PHONO PREAMP? If so, can you state what you experienced with sound improvement?

Background for my query:

I recently upgraded my TT cartridge to an Audio Technica VM540ML and I’m very happy with the unlocked quality of my favorite rock and prog albums. I’m now wondering what sort of additional demonstrable sound improvement I can squeeze out of my Onkyo A-9010, or have I simply topped off? I’m wondering if a cartridge upgrade feeding into an existing amp is the only way to go, and if the addition of an external phono preamp, regardless of type or price will be a nominal change as the Onkyo is the bottleneck based on its own design limitations?
 

anmpr1

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Audible (i.e., not imaginary) differences will definitely be possible if your outboard RIAA circuit allows for variable impedance loading, which will affect the FR of a MM phono cartridge.

If your preamp has a line level auxiliary input you can insert the outboard phono stage there, and then make comparisons by switching. However it is best if levels are matched, and there is no guarantee that the line + RIAA will match the onboard phono level. An advantage of this option is that you will now have two phono inputs, and can buy another turntable. I'm only half kidding, because back in the analog days most preamps had two phono stages, since a lot of folks owned two record players. (I'm looking in the mirror, here :) )

Your AT VM540ML frequency response is a bit on the 'hot' side, so switching to a different cartridge with a less pronounced high end will no doubt result in an audible change.

The idea that an outboard RIAA circuit will necessarily audibly 'improve' what is in your preamp is a stretch. Find a dealer that will make a loan, do your own comparison and then report back. That is the only way to be sure.

A lot of stand alone devices have tubes sticking out of them, and you could notice a difference due to tube distortion. I think some are solid state (opamp, JFET etc) based (for low noise) with a tube follower for 'conditioning'.
 
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mschool

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Audible (i.e., not imaginary) differences will definitely be possible if your outboard RIAA circuit allows for variable impedance loading, which will affect the FR of a MM phono cartridge.

If your preamp has a line level auxiliary input you can insert the outboard phono stage there, and then make comparisons by switching. However it is best if levels are matched, and there is no guarantee that the line + RIAA will match the onboard phono level. An advantage of this option is that you will now have two phono inputs, and can buy another turntable. I'm only half kidding, because back in the analog days most preamps had two phono stages, since a lot of folks owned two record players. (I'm looking in the mirror, here :) )

Your AT VM540ML frequency response is a bit on the 'hot' side, so switching to a different cartridge with a less pronounced high end will no doubt result in an audible change.

The idea that an outboard RIAA circuit will necessarily audibly 'improve' what is in your preamp is a stretch. Find a dealer that will make a loan, do your own comparison and then report back. That is the only way to be sure.

A lot of stand alone devices have tubes sticking out of them, and you could notice a difference due to tube distortion. I think some are solid state (opamp, JFET etc) based (for low noise) with a tube follower for 'conditioning'.

Thank you very much for your response, which I have read through a few times. I think that what you are saying is two things. One, I could try different cartridges going into the onboard internal phono preamp, and experience demostrable change in sound. Second, as long as the external preamp has controls, such as gain and other adjustments, I could also experience improved sound quality with the existing AT VM540L.

A "brick" style external preamp that offers no adjustment with only offer one flavor of sound change, if any. Is this an accurate parsing of your explanation?
 
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anmpr1

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Correct me if I'm wrong; what you are saying is that the only way I am going to change the quality of the sound of my records is to use a cartridge that is different in build quality to my AT VM540ML.
It is not the only way, but it is probably the most noticeable way. BTW, I think the 'build quality' of your AT cartridge is fine. I have nothing against their QC. A different electrical 'design' will, however, likely effect a sonic change. If I was into the low to moderate analog cartridge market I'd try one of Joe Grado's models. I admit to never owning one, but they aren't expensive (not talking about their pricey 'wood' models) and I've not heard anything to disqualify they, from a sonic perspective.

I have no idea about the Japanese market from a price to value standpoint.

My impression of the Japanese analog audio scene is that it's not only the land of the rising sun, but the land of rising price moving coils. I can't say anything about those. I drew the line at plebian Denons, and even those are sky high these days.

The Japanese MC scene is the Faubourg Saint-Germain of analog. Once you start living there, many more variables for changing the sound are possible: head amp or transformer; more loading options; onyx or urushi vermillion; rosewood or pearwood. All beyond my payscale!
 

watchnerd

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I have no idea about the Japanese market from a price to value standpoint.

My impression of the Japanese analog audio scene is that it's not only the land of the rising sun, but the land of rising price moving coils. I can't say anything about those. I drew the line at plebian Denons, and even those are sky high these days.

The Japanese MC scene is the Faubourg Saint-Germain of analog. Once you start living there, many more variables for changing the sound are possible: head amp or transformer; more loading options; onyx or urushi vermillion; rosewood or pearwood. All beyond my payscale!

The entire Japanese MC market isn't Koetsu and Miyajima.

I have several top end AT MCs (ART7, AT33SA).

They're slightly less pricey that their Ortofon equivalents.

So I wouldn't say Japan is any pricier than Europe.

But MCs, in general, are not for those on a budget.
 
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mschool

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I might have been approaching this the wrong way, and you've shown me so. My amp is fine. The internal phono preamp is fine. The seller of the TT (a Denon DP 47F) shipped along a discontinued MM cartridge; a DIATONE AMG-44 cartridge. The sound with it was very good, but not great. The Audio Technica cartridge was demonstrably clearer, more detailed, and brighter. I'm going to purchase a second headshell for my TT and compare the Diatone with the Audio Technica; and then I'll have sense of the sonic differences between the two.
 

watchnerd

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I might have been approaching this the wrong way, and you've shown me so. My amp is fine. The internal phono preamp is fine. The seller of the TT (a Denon DP 47F) shipped along a discontinued MM cartridge; a DIATONE AMG-44 cartridge. The sound with it was very good, but not great. The Audio Technica cartridge was demonstrably clearer, more detailed, and brighter. I'm going to purchase a second headshell for my TT and compare the Diatone with the Audio Technica; and then I'll have sense of the sonic differences between the two.

What's the effective mass of your tone arm?

Swapping headshells should best be done with an eye to improving cartridge resonance vis a vis compliance.
 
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mschool

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Good question. It's from 1985. Vinyl Engine describes the tonearm as follows:

Arm type: dynamically balanced, straight tube tonearm
The Denon DP-47F features a low mass tonearm with Q-damping method.
Low frequency resonance caused by the cartridges compliance and the effective tonearm mass is electronically damped both horizontally and vertically to effectively suppress crosstalk and inter-modulation distortion.
The dynamic servo tracer maximises the performance of the low mass tonearm and results in a record reproduction of excellent sound image with minimum noise and distortion.

BTW - there is a specific headshell design and material for this TT. I'm patiently waiting for one to appear in the used markets here.
 

watchnerd

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Good question. It's from 1985. Vinyl Engine describes the tonearm as follows:

Arm type: dynamically balanced, straight tube tonearm
The Denon DP-47F features a low mass tonearm with Q-damping method.
Low frequency resonance caused by the cartridges compliance and the effective tonearm mass is electronically damped both horizontally and vertically to effectively suppress crosstalk and inter-modulation distortion.
The dynamic servo tracer maximises the performance of the low mass tonearm and results in a record reproduction of excellent sound image with minimum noise and distortion.

BTW - there is a specific headshell design and material for this TT. I'm patiently waiting for one to appear in the used markets here.

Okay, ignore what I said, then, if it's got some fancy pants auto compliance adjuster. ;)

Personally, my preferences are in the opposite direction, trying to avoid vendor lock and proprietary tech. My tonearm uses bog standard SME-type headshells.
 

AnalogSteph

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Comparing the two cartridges may be a mixed fruit basket - as @anmpr1 effectively already pointed out, the requirements of different MM cartridges in terms of output loading (capacitance and resistance) can vary quite a bit. The following will contribute to load capacitance:
* tonearm cabling
* cable to phonopre
* phonopre input capacitance

A lot of bog standard phono stages have a 47 kOhm || 220 pF input capacitance - add the typical 130 pF or so for tonearm cabling and a short phono cable, and we're at 350 pF. While some cartridges will work fine like that, a fair few ATs in particular tend to be unhappy and exhibit noticeable treble peaking. They may actually require a maximum of 200 pF total, so amplifier input capacitance should be something like 47 pF in this case. You can always more externally by making corresponding adapters if really needed, but you can't make it any less. Alternatively, you can reduce the resistance (a lot of people are using 36k for ATs) - this will flatten out the top end, but frequency response will also start to drop at a lower frequency.

None of this is new, the first phono stages with adjustable input capacitance actually date from the 1970s. If you are serious about this whole vinyl business, you should have one like that, and a test record with a frequency sweep / sines. Recording that should allow setting up input capacitance for best frequency response flatness after doing a coarse adjustment by ear.

That BTW, is something you cannot do with MCs - while those are quite unimpressed by these loading shenanigans, their native response commonly includes a slight coloration. Perhaps the best way of listening to vinyl records really is recording them and playing back a canned digital version - it eliminates acoustic feedback from the loudspeakers, you can EQ as much as you want, and for a one-time affair you can even consider going to lengths such as wet playing. A good ADC should be fine at 48 kHz, a lesser one may require 96 kHz sampling - things could be downsampled to 44.1 kHz if needed afterwards, we've got good resampling algorithms these days (fun fact: the one in Audacity is a good one...).
 

watchnerd

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That BTW, is something you cannot do with MCs - while those are quite unimpressed by these loading shenanigans

MCs are certainly quite indifferent to capacitive loading, but their response to resistance loading changes is easy to measure and mathematically model.

mcbw.gif


Math and calculators here, MCs at 2nd half of the page:

http://www.hagtech.com/loading.html

The phono stage of my amp allows adjustment of resistance loading at the MC input.

For my cartridge, the main coloration / ringing is in the ultrasonic range, due to its low inductance.
 
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Sasha

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I’ve got a VM540ML and an AT440MLb and they can be very hot in the treble, but they’re easy to tweak.

As several very sensible posts above have stated: this brightness can be due to excessive capacitance. I had to tameboth AT carts’ high end with a combination of a low capacitance phono stage (a modded CA 651p) and some 58k (iirc) resistors wodged into some cheap screw-down RCA connectors and connected via a Y-adapter. No soldering required.

If you have a multimeter you can quickly measure the capacitance of your turntable cabling to work out if that’s causing excessive brightness. If it’s fine but you just prefer less high end you can use lower value resistors to soften the high end even more.

nb. If the issue is excessive capacitance then it causes a pronounced high frequency peak which is followed by a dramatic roll off. You can’t fix it by using the resistor trick as you simply end up with very little high end at all!
 
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