Cartridge for a Current amplifying phono stage?

[Qwin]

Ok, noted Alan. It might behave a bit differently when used in balanced current mode, but I'm pretty sure the basic character will still be the same.

[blake]

I've used the Aqvox for about 12 years now; mine is an early Mark II with up to 14 dB of gain adjustment on the gain pots.

I'm surprised you find the AT 33 PTG dull or lacking in dynamics with the Aqvox. For mono I use an AT 33 Mono which would appear to be very similarly spec'd and I don't find it to be that way at all, and equal in that area to the Accuphase AC2 I'm using for stereo.

For reference, the AT 33 Mono is spec'd at .35 mV output and 10 ohms internal impedance, the Accuphase at .18 mV with a 4 ohm internal impedance. I have the gain pots set at +2 with the AT 33 Mono and +8 with the Accuphase. The cartridges are on two different arms on the same table, both using the same version of the same phono lead (an Audio Sensibility cable). Using +8 dB with the AT 33 Mono would make my ears bleed in my system.

I also used a couple of rebuilt Ortofon MC 20 Supers in the past and modified Denon 103R's. The Accuphase is simply a grossly superior cartridge to those with the Aqvox, even though it is spec'd similarly to the MC 20 Super.

My gut feeling is that the Aqvox is going to work best with low internal impedance cartridges (2-10 ohms) with outputs in the .15 to .4 mV range. I also ran an Audio Technica AT 3 MONO/LP for a while (with 1.2 mV output and 40 ohm internal impedance) and felt that the balanced input/output with that cartridge simply provided too much gain, even with the gain pots turned to 0.

I know that I'd be reluctant, based on my experience with it, to be popping for any cartridge with an output of .5 mV or greater, almost regardless of internal impedance.

The gain pots on the Aqvox have a huge overall effect in my system and the sweet spot is exceedingly narrow with any given cartridge in my opinion: certainly within 1-2 dB. But no doubt, as you say, that subjective listening preferences come into play.

[Qwin]

Hi Blake
Thanks for sharing your experience.
You are right about the +14dB gain. I said +12dB from memory. Mine is also an early Mk II.
Are you using yours with balanced inputs as a current amplifier? I presume you are, but you mentioned "Phono leads" which I always associate with RCA connections and single ended input. Also, the Accuphase has a higher current output (0.045mA) to the AT33 mono (0.035mA) so should need less gain not more if used balanced/current. The AT3Mono has a current output of only 0.03mA, all your comments seem to relate to the voltage output, the higher that is the less gain you used. So I am a bit confused. To calculate the Current output, divide the output voltage (usually specified for 1kHz@5cm/sec) by the cartridges internal inductance/resistance. eg 1.2mV/40ohm=0.03mA for the AT3mono. The voltage output is irrelevant on a current amplifier, only as much as it is used to calculate the current. High voltage / low impedance = high current. But high voltage / high impedance can still be a low current output.

It may be that my balanced interconnects from the cartridge are the problem. I started using these leads at the time I fitted the 33PTG. I made them myself, following the instructions on the Aqvox web site, which is:
A twisted pair of conductors with a separate single strand of "shield" wire laid alongside the twist and connected at the phono stage end only, to pin1 of the XLR input. These all wrapped in an expandable woven jacket. The left and right channels in separate jackets. The shield wire acts as an aerial picking up interference and is floating, being connected at one end only. This is the same construction as Aqvox's own leads, they say a full braided shield cable is not as open sounding, so I followed their instructions to the letter. They use either Copper or Silver wire for a warmer/cooler sound, I used Gold plated OFC Copper. My leads are 1m long.

[blake]

Hi Ken:

Yes, I'm running into the balanced/current input and you're absolutely correct that the current numbers as calculated on my 3 cartridges are counterintuitive in terms of the settings I've arrived at with the gain pots. But there's no question in my mind that the general area in which I have the settings is correct (ie. the Accuphase needing the highest adjustment on the gain pots and the AT 3 MONO/LP having too much gain even with the pots set to 0).

Aqvox stated (at least with the literature that came with my unit) that the gain provided at the XLR inputs ranges from 55-75 dB depending on output voltage/impedance of the cartridge (current) and if you take those numbers into account, my gain settings on the Aqvox pot are really not that much different than they would be on a typical voltage phono amplifier. The Aqvox cartridges, if you take a close look at them, appear to be, both physically and technically, reworkings of the Ortofon MC 20 Super, (which is very similar in terms of output voltage & impedance to the Accuphase) and their recommendation of 14:30 to 15:30 hours on the gain pots for those cartridges is where I've essentially ended up with on the Accuphase and also the MC 20 Supers when I ran them. I'm closer to 14:30, or +8 dead on as I find that with the gain pots adjusted higher the sound starts to harden up and the soundstage collapse.

So I think that strictly trying to maximize the current the cartridge provides may not necessarily be the way to go, although I do think that sticking with cartridges that have a fairly low internal impedance is definitely a good idea in terms of how the current input works on the Aqvox.

One thing which I thought about after I posted which I did not mention is that I run balanced out as well as balanced in, so I'm running fully balanced from cartridge to speaker. I'm not technically astute enough to know if you are running XLR in on the Aqvox and RCA out to your preamp or integrated how much that would affect the typical additional 6 dB of gain that you are going to pick up with a balanced connection.

Others (or Aqvox) might have to chime in on that for you, but it is possible that might be coming into play for you if you are using the RCA outputs and if the 6 dB additional gain was negated in that setup then your +8 and my +2 for our similarly spec'd AT cartridges would essentially be the same. And that would also probably allow you to use higher output cartridges that would be pushing the limit for me.

If you are thinking of purchasing a new phono cable and want something reasonable, I'd highly recommend the Audio Sensibility Impact cable. DIN to XLR is about $225 CAD or about 140 pound sterling and it is a remarkable cable for the money. If you do purchase one pay the additional few quid to have it burned in.

[rubber duck]

Yes, my 33PTG requires the input gain to be at quite a high level, +8dB
Are you using them Balanced ?

Apologies for the late reply. Yes, my 33 is run in balanced/current mode with 3dB gain. But mine is a Mk I version. Just turned on the system last night for the first time since July(!) and can confirm that the AT33PTG is pretty dynamic through the Aqvox.

[blake]

Apologies for the late reply. Yes, my 33 is run in balanced/current mode with 3dB gain. But mine is a Mk I version. Just turned on the system last night for the first time since July(!) and can confirm that the AT33PTG is pretty dynamic through the Aqvox.

Hi Jeff: Are you running XLR's out or RCA's out?

[Qwin]

Blake/Jeff
Thanks for the replies.
I'm fully balanced throughout my system.

So there seems more to it than just requiring a high current output.

I need special leads as I use a Linear tracker with a particular make (diameter) of 5 pin Din plug needed, as this is clamped into the base of my arm.
I have two separate XLR cables for R/L channels that terminate in the single five Pin Din plug.

The combination of leads from my cartridge to Din socket & Din plug to Aqvox may be the issue.

When I used continuous Silver wires from the cartridge tags, straight into the back of my Pro-Ject Voltage amplifying Phono stage, the 33PTG sounded great. Same when using these leads into the Aqvox in Voltage mode. They were very short and very delicate though, unshielded multi strand Silver wires wrapped in silk, just loose flapping about. The weight of the XLR Plugs could break them, so I wanted something more robust.

I think I need to do some investigating regarding the leads. If you get into hundreds of pounds, I may as well get the Aqvox leads, I was hoping to avoid that kind of expenditure though.

Blake, you missed the answer in Jeffs reply "Yes, my 33 is run in balanced/current mode with 3dB gain"

Edit: The two Aqvox cartridges are basically the same, the Prestige has carefully matched component values, that's the only difference, but you pay a lot for it. They are on offer at Aqvox webshop. Premium reduced from 795 Euro to 495 Euro. Prestige reduced from 995 Euro to 695 Euro, VAT included but not shipping. The Premium looks tempting at that price.

[Matt_J]

Hi Ken,

I'm surprised you think that Benz aren't a good match, my Glider SL sounds terrific into my RSL phono stage, more alive than quite a few carts I've tried including an AT33SA. I don't know it's current output but it's the best I've ever heard it, including into another current amplifier the Dynavector P-75, although it also sounded great into that!

Won't have a traditional phono stage of any sort again after hearing mine.

[Qwin]

Hi Ken,

I'm surprised you think that Benz aren't a good match, my Glider SL sounds terrific into my RSL phono stage, more alive than quite a few carts I've tried including an AT33SA. I don't know it's current output but it's the best I've ever heard it, including into another current amplifier the Dynavector P-75, although it also sounded great into that!

Won't have a traditional phono stage of any sort again after hearing mine.

I was basing this purely on current output and a review saying a particular 0.06mA cartridge was a good match for a current amplifier.
Most AT and Benz are around 0.03mA plus a lot of others, so I was looking for something higher.
After the comments from some other Aqvox 2ci users, it looks like current is not the only deciding factor for compatibility, so I'm really back to square one and looking at how well suited my interconnects are.

I've always liked the Benz Gliders and heard a few, including the gull wing, they look really cool as well

They could be back on the radar along with the AT ART9

[rubber duck]

Hi Jeff: Are you running XLR's out or RCA's out?

Blake/Jeff
Blake, you missed the answer in Jeffs reply "Yes, my 33 is run in balanced/current mode with 3dB gain"

Ken, I think Blake is asking if my tonearm cable is wired with XLRs or if I use RCAs with an XLR adapter. I think this is an important point. Without wishing to complicate matters, my Aqvox has had the XLR sockets replaced with RCA sockets that retains balanced connection. So I can run my existing RCA tonearm cable directly into the balanced input of the Aqvox without adapters.