[cactuscowboy]

I'm using the Bugle Pro for 78 rpm playback and conversions to WAV.  I'm having a serious distortion problem.  Equipment:

Bugle Pro (gain 50)
Technics SP-15 turntable w/Stanton 500VE cartridge (78 rpm playback)
Pioneer SX-950 receiver
PC with Realtek AC97 soundcard

Set up #1

Turntable - Bugle Pro - Sound Card
result: bad hum, distortion, very poor recording

Set up #2

Turntable - Bugle Pro - Receiver - Speakers
result: beautiful, clean sound

Set up #3

Turntable - Bugle Pro - Receiver (tape out) - to Sound Card
result: same bad hum and distortion as set up #1

Set up #4

Turntable - (phono input) Receiver (tape out) - to Sound Card
result: beautiful, clean sound, perfect recording

I've fiddled with ground wires, and can't find any loose wires or obvious bad solder joints in the Bugle Pro.  Not sure if it matters, but I did goof when building the Bugle Pro.  I neglected to solder the 3 "8 pin solder tail dip sockets" onto the PCB, and soldered the 3 "opamps" directly to the PCB.

This is driving me crazy.  I'm admittedly no expert in electronics and hope someone can suggest a possible cure or at least a place to start looking for trouble.

[hagtech]

I assume you can record an FM broadcast ok?  Soldering opamps directly is a good thing.  Direct connection of audio system to computer system can result in ground and signal noise.  Best to keep them separate, if possible.  If not, then at least plug into same outlet.

jh

[cactuscowboy]

Thanks for the reply Jim.

I believe the problem lies with the soundcard being overloaded with too strong of a signal.

The Bugle Pro, with its gain of 50, coupled with a relatively high output cartridge (4.6mV), requires that I adjust the "Line In Volume" on my PC to just barely above the off position.

So I'm thinking I need to pursue one of the following:

1.  A new/better soundcard.
2.  Find a means to decrease the signal going into the soundcard since I'm at the limits of adjusting on the PC itself.
3.  Modify the Bugle Pro to decrease the gain to 40.

I built the Bugle Pro with a gain of 50 because one of my cartridges is relatively low output at 0.6mV.

Question:  What is the optimum (best compromise) gain for the Bugle Pro considering that I'm using cartridges with outputs ranging from 0.6mV to 5.0mV?

Any further comments or suggestions would be appreciated.

Thanks,
Dave in Wyoming

[cactuscowboy]

I assume you can record an FM broadcast ok?  Soldering opamps directly is a good thing.  Direct connection of audio system to computer system can result in ground and signal noise.  Best to keep them separate, if possible.  If not, then at least plug into same outlet.

jh

I added emphasis to above quote.

If the soundcard and audio editing software are on my PC, how would I get the signal from playing records & tapes onto the PC without a direct connection?

Thanks,
Dave in Wyoming

[hagtech]

Through a transformer or balanced connection (pro & studio style).  Often it is important to isolate the computer ground from audio system ground.  Installation dependent.

jh

[cactuscowboy]

I got the problem fixed.

A ground loop isolator did not make any change.  But a small sound mixer from Radio Shack positioned between the Bugle Pro and sound card did reduce the signal enough to eliminate the buzz/distortion problem.

Thanks for your replies Jim.

I've been very happy with the Bugle Pro, it's an excellent design.

Best regards,
Dave in Wyoming

[PatOMalley]

I know I'm late to this conversation but I had the same issue with My Bugle Pro until I reduced gain to 40dB.
Also shielding the internal input/output hookup wires helped as well. Also shielded the connections coming from the switches.. but the reduction to 40dB reduced noise to way above listening level.

[cactuscowboy]

I know I'm late to this conversation but I had the same issue with My Bugle Pro until I reduced gain to 40dB.
Also shielding the internal input/output hookup wires helped as well. Also shielded the connections coming from the switches.. but the reduction to 40dB reduced noise to way above listening level.

Thanks for the reply Pat.

I've been thinking about going to a 40db gain.  I use the Bugle Pro for three turntables, so it's kind of a compromise situation with cartridge outputs ranging from 0.6 to 5.0 mv.  But I'm using it primarily for 78 rpm playback and it just seems a bit loud with the higher output cartridge.

When you say "shielding" the wires, exactly what did you do?  Extra insulation I presume?

[PatOMalley]

Extra insulation by way of shrink tubing, or you can wrap tinfoil around the wire then wrap with electrical tape. Looks ugly. I did all that and it reduced hum. I checked my grounds coming from input and re soldered. I was think of getting rid of the "Pro" part, all the caps and resistors as I was thinking they were one big antenna.  Reducing to 40 was the clincher.

Maybe you are a good candidate for the Piccolo headamp?

[cactuscowboy]

Thanks again Pat.

I am going to try 40 gain.  And I'll add extra insulation on the wires.

[hagtech]

Shielding is not about insulation.  It's another conductor.  Usually we use coaxial cable for "shielded" signal runs.

jh

[cactuscowboy]

Shielding is not about insulation.  It's another conductor.  Usually we use coaxial cable for "shielded" signal runs.

jh

Is there any benefit to replacing the standard "hook up wire" in my Bugle Pro with coaxial cable or wrapping the wire with aluminum foil/electrical tape or putting shrink tubing on the wire?

Referring to the photo of the Bugle Pro on the hagtech website, I notice the wires are arranged in 'twisted pairs'.  Is there any benefit to that arrangement aside from aesthetics?

Thanks,
Dave in Wyoming

[hagtech]

The twisted pairs offer a little bit of shielding.  Coax is better for this application, just more difficult to solder.

jh