[davidb928]

Hi,

I just took my Denon DP-1200 out of storage after 15 years and hooked it up to an Adcom Preamp that has a good phono stage. But I'm getting lots of hum and the gain isn't what it needs to be (I think)—the volume knob has to be cranked much higher than with line-level components.

So, a few questions: how do I get rid of the hum? I assume it's due to the lack of a grounding wire between my preamp and the turntable? Each are about 6 feet apart—what kind of wire should I buy to use for grounding?

As for the gain/volume, I used to have a "pre-preamp" that I used with the Denon, because it has a low-output (0.4 mV) moving coil cartridge. But I can't find the darn thing. Are there any good low-cost MC step up preamps on the market I could use for this?

Any help would be greatly appreciated.

[Steve Eddy]

I just took my Denon DP-1200 out of storage after 15 years and hooked it up to an Adcom Preamp that has a good phono stage. But I'm getting lots of hum and the gain isn't what it need to be (I think)—the volume knob has to be cranked much higher than with line-level components.

Question.

Even though you're having to turn the volume knob up more than with line level components, are you able to get sufficient volume levels?

If so, don't worry about it. The less you have to turn the volume knob up, the more excess gain you have in the system. Excess gain means excess noise and distortion. The only time you'd need to worry about not having enough gain is if you're not able to achieve sufficient volume levels with the volume knob turned all the way up.

So, a few questions: how do I get rid of the hum? I assume it's due to the lack of a grounding wire between my preamp and the turntable?

That could very well be. The metal parts of the tonearm, if they're not grounded, can act to capacitively couple noise into the cartridge leads.

Each are about 6 feet apart—what kind of wire should I buy to use for grounding?

Did the turntable not come with one?

As for the gain/volume, I used to have a "pre-preamp" that I used with the Denon, because it has a low-output (0.4 mV) moving coil cartridge. But I can't find the darn thing. Are they are good low-cost MC step up preamps on the market I could use for this?

There are. But depending on your answer to my question above, you may not need one.

se

[davidb928]

Thanks for the info, Steve. To your points:

1. Yes, I can get adequate volume. So looks like I can forgo the step-up device and save some clams.

2. If the TT came with a grounding wire, I lost it. But tonight I bought some Radioshack 18-gauge speaker wire and hooked one strand of it to the grounding screw of the TT and the same on the preamp. It seems to have gotten rid of most of the hum. Not sure if I was supposed to use both strands, but it seems to be working.

Now all I need is a record-cleaning kit to tame at least some of the tics and pops, and I'll be all set.

By the way, my kids think the TT is an alien artifact—they literally have never seen a vinyl record, let alone a TT. We're all listening to Peter and the Wolf; they're transfixed!! I think I'm on to something.

Can't wait to start revisiting my old used record haunts in NYC...

Thanks again for the advice.

David

[GBB]

Even though you're having to turn the volume knob up more than with line level components, are you able to get sufficient volume levels?

If so, don't worry about it.

I'd respectfully disagree.  A step up transformer doesn't just provide some gain.  It also transforms the load seen by the cartridge.  For example, a 1:10 step up transformer will make the typical 47K load of a phono stage look like 470ohms to the cartridge.  A 1:20 step up will make it look like 117.5ohms. 

My experience has been that most MC cartridges are very sensitive to the loading and one must tweak the loading to get the best sound.  If you just load the cartridge with a low resistance then the signal level drops significantly and you end up not having enough gain.  So I think if you want to get the best sound out of your Denon then you'd be advised to get either a good step up transformer or a good pre-preamp with adjustable loading. 

Hagtech offers a pretty good pre-preamp for a reasonable price that could be worth a look.  If you can solder then you can buy the half-kit and it's very reasonable.  Even the prebuilt version isn't too expensive. 
Personally, I like step up transformers and if you're willing to solder on your on RCA jacks and plugs then you can also do things for not too much money.

---Gary

[Steve Eddy]

Thanks for the info, Steve. To your points:

1. Yes, I can get adequate volume. So looks like I can forgo the step-up device and save some clams.

Well, perhaps not. See my reply to GBB below.

2. If the TT came with a grounding wire, I lost it. But tonight I bought some Radioshack 18-gauge speaker wire and hooked one strand of it to the grounding screw of the TT and the same on the preamp. It seems to have gotten rid of most of the hum. Not sure if I was supposed to use both strands, but it seems to be working.

Just the one strand is sufficient. All you're wanting to do is keep the conductive bits of the tonearm at the same potential as your preamp's ground.

Now all I need is a record-cleaning kit to tame at least some of the tics and pops, and I'll be all set.

Great!

By the way, my kids think the TT is an alien artifact—they literally have never seen a vinyl record, let alone a TT. We're all listening to Peter and the Wolf; they're transfixed!! I think I'm on to something.

Hahaha! Too cool! How old are they?

Thanks again for the advice.

You're welcome. Good luck!

se

[Steve Eddy]

I'd respectfully disagree.  A step up transformer doesn't just provide some gain.  It also transforms the load seen by the cartridge.  For example, a 1:10 step up transformer will make the typical 47K load of a phono stage look like 470ohms to the cartridge.  A 1:20 step up will make it look like 117.5ohms.

Yes, though that presupposes you're driving a typical MM phono input.

That may possibly be the case here and if it is, then we're in agreement. davidb928 should check and see if his Adcom preamp has an MC input or just the 47k MM input.

Hagtech offers a pretty good pre-preamp for a reasonable price that could be worth a look.  If you can solder then you can buy the half-kit and it's very reasonable.  Even the prebuilt version isn't too expensive. 
Personally, I like step up transformers and if you're willing to solder on your on RCA jacks and plugs then you can also do things for not too much money.

Yes. CineMag's CMQEE-3440A has been very well received as an MC step-up and it doesn't cost an arm and a leg. Think they're only something like $35-$40 each.

se

[davidb928]

Ok, just checked the Adcom preamp manual, and it specifically says that the phono stage is designed to accept signals from high-output moving coil cartridges or MM cartridges that are rated at 2.2 mV or higher. My Denon Cartridge must be low-output, since its product literature says it puts out .5 mV. In such cases, the Adcom manual recommends the use of a step up or pre-pre amp.

So I think I'll try one of the lower-cost units recommended here and see if it makes a difference.

I have to say, after listening to several records last night, something is missing; I do get adequate volume, but there's just no there there.

I've been reading the various tweaking threads, but I think the first step might be to get the gain/volume question resolved, then move on other things such as cartridge alignment, leveling, etc.

BTW, my girls are 10 and 7 and loving the extra "time" they're getting with me, listening to great music. It's actually keeping them off the computer, so however the TT ultimately sounds, it's already doing it's job!!!

Thanks again to all—this looks like a great site/community. 

[lcrim]

While not nearly as cheap as the CineMags another alternative is the Denon AU-300LC  available @ Audio Cubes II  http://www.audiocubes2.com/category/Vinyl+Accessories/product/Denon_AU-300LC_MC_Cartridge_Boosting_Trance.html
I have heard this one and its decent.
Another I have not heard but is positively reviewed is the Lundahl TRansformers from K&K Audio
http://www.kandkaudio.com/phonostage.html
$275 for  the kit and $335 built-not chump change but highly thought of-I'm considering it myself.
Good luck.