Separate phono preamp

leftside

AK Member
I obtained a Blue Circle BC23 Level 2 phono preamp a couple of weeks ago. I thought I'd give it a try instead of a step-up-transformer and the C34V phono input.

The results from below are with no music playing.

1) With the SUT/C34V phono combo I could hear a definite hiss and hum when turning the volume knob halfway. A couple of clicks past halfway and the meters on the 2155 would start to move. This never really bothered me because even at just less than halfway the sound was very loud in my small upstairs room.

2) With the BC23/C34V line input combo I now have absolutely zero hum. There is still a slight hiss, but I have to turn the volume knob quite far. The meters on the 2155 start to move at near max volume.

I couldn't notice any difference in sound quality between 1) and 2), but 2) was much quieter. I'm keeping 2 :)

With the CD input there is 0 hiss or hum. Quite remarkable for such an old unit.
 
BC23 is designed to drive a line or Aux input. There are dip switches inside to set the gain and impedance for MC and MM cartridges. All phono pre amps have a little noise, some more than others. That's why some folks prefer step up transformers for MC driving a MM input. The only issue then is hum. I prefer HO Dynavector moving coil for most installations as you don't need the pre-preamp or external pre-amp, just plug in to the MM input and go.
 
Yes twiiii, I'm using the BC23 to drive the line input on the C34V. And yes, I'm using the correct dip switches for my Dynavector 20*2 low output MC cart.

The BC23 has very little noise. I found the SUT into the MM input to be noisier than the BC23 into the line input. There was hum with the SUT, but zero hum with the BC23.

I've tried a HO MC cart with the C34V MM input, and the LO MC cart with an external preamp (the BC23) into the C34V line input is quieter than the C34V MM input.

It was you who first recommened I try an external phono preamp (a Dynavector P75 I think), so thanks for the suggestion.
 
Yes twiiii, I'm using the BC23 to drive the line input on the C34V. And yes, I'm using the correct dip switches for my Dynavector 20*2 low output MC cart.

The BC23 has very little noise. I found the SUT into the MM input to be noisier than the BC23 into the line input. There was hum with the SUT, but zero hum with the BC23.

I've tried a HO MC cart with the C34V MM input, and the LO MC cart with an external preamp (the BC23) into the C34V line input is quieter than the C34V MM input.

It was you who first recommened I try an external phono preamp (a Dynavector P75 I think), so thanks for the suggestion.

Any time you turn up the volume and the Pre is in the phone stage you'll get hum. When you add a Phono Pre to your MM & MC you amplify it further. Going in to a Line Level or AUX reduces it again. Just think of it this way your cartridge is a microphone and as you add amplification you get a hum when it's hanging in the air.

I am going into an MC input with a SOTA Phono head amp and a Sumiko blackbird cartridge. Sure that the cart will play fine in a MM input all by it's self, even better with more volume in the MC input, now even better with the head amp and MC input. If you add to much gain you will start to distort the sound. Yeah I get a bit of hum but not when records are playing or when the volume is low. The added benefit over a small hum is outstanding SQ, stage presents, open airy bloom and the loudest input I have.

CDs and digital music doesn't win the loudness war in my system:thmbsp: However digital will destort and start kicking in the autoformers sooner at a lot lower volume. So don't be afraid to try diferent setups and inputs and you might have some hum but what does the music sound like, what are your autoformers doing if you have them.
 
So don't be afraid to try diferent setups and inputs and you might have some hum but what does the music sound like, what are your autoformers doing if you have them.
Yes trying different setups is half the fun. Right now I have ZERO hum (but a little hiss) and the music sounds as good as it ever has for my vinyl setup:
Dynavector 20*2L MC -> BC23 -> C34V Line Input -> MC2155

I'm going to take the C2300 upstairs to the vinyl room and see how that compares to the above in different configurations (C34V only has MM input, C2300 has MM and MC input).
 
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So don't be afraid to try diferent setups and inputs and you might have some hum but what does the music sound like, what are your autoformers doing if you have them.
Yes trying different setups is half the fun. Right now I have ZERO hum and the music sounds as good as it ever has for my vinyl setup:
Dynavector 20*2L MC -> BC23 -> C34V Line Input -> MC2155

I'm going to take the C2300 upstairs to the vinyl room and see how that compares to the above in different configurations.
 
With the 2300 you can manipulate the loading on the MC input to match with the Dynavector 20/2L MC & BC23 better.
 
I just unpacked my TT out of storage and connecting a new cartridge (Lyra Delos LOMC). It's been too long to really compare, but I feel that the Lyra, or the C2300 is lacking a little bite. Think snap of a snare drum, grunt of a guitar, etc. It's been too long to compare it to my last cartridge (now damaged), but it may have been the same kind of soft presentation. Do you find the same with the C2300 alone, and would you recommend a standalone phono preamp?

Thanks!
 
I just unpacked my TT out of storage and connecting a new cartridge (Lyra Delos LOMC). It's been too long to really compare, but I feel that the Lyra, or the C2300 is lacking a little bite. Think snap of a snare drum, grunt of a guitar, etc. It's been too long to compare it to my last cartridge (now damaged), but it may have been the same kind of soft presentation. Do you find the same with the C2300 alone, and would you recommend a standalone phono preamp?

Thanks!
Are you trying different loadings on the 2300? it is adjustable.
 
When I had my MT10 (Clearaudio cartridge) connected to my C2300 the only thing that was lacking was my bank account. I never really longed for anything else. Same goes for the MT10 with the C50 (interestingly, the only area where I felt the C50 really excelled).

As 4-2-7 said, the loading is adjustable in the C2300 and it needs to be set properly. I never had a wisp of hum hiss or anything else, and my temporary setup was FAR less than ideal.
 
Yeah I've been alternating between 200 and 500. The 200 helps the bass a little, with the 500 being a bit crisper. I do think it's starting to break in and present itself better. The guy I bought it from also suggested Clearaudio, while preferring the Delos for imaging (which is fantastic).
 
Well I tried the C2300 with my turntable and with/without the phono preamp. Oh man - the sound was super clean, with very, very little noise. I loved it. But, and I might get killed for saying this... I think I prefer the sound with the C34V. Maybe it's just "different" and I am more used to the C34V combo?

Even though the sound with the C34V isn't as clean, and there is certainly a little more noise (though undetectable when listening), it seems to have a certain warmth when combined with vinyl that I really like.
 
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