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Hagerman Bugle3 Phono Stage Review

Rate this phono stage:

  • 1. Poor (headless panther)

    Votes: 3 2.6%
  • 2. Not terrible (postman panther)

    Votes: 39 34.2%
  • 3. Fine (happy panther)

    Votes: 66 57.9%
  • 4. Great (golfing panther)

    Votes: 6 5.3%

  • Total voters
    114

SoNic

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It is trivial to design the feedback system to have the circuit free of overload recovery issues. It is trivial to test with transient/impulse signals.
And that's the fallacy... "it's trivial".
While for passive networks is just simple reality.
 

AudioSceptic

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It isn't only rumble.
Since a seismic sensor like a pickup cartridge/arm combination only starts to produce an accurate transduction from around 2x the natural frequency of the mass on the compliance (the exact value depends on damping which is forced to be in the "wrong" place for excellent performance on a record player) ALL of its output below that frequency will be inaccurate and boosted so is best removed anyway, even if the record player has low rumble.
Would any competent turnable have any rumble serious enough to require filtering out in any case?
 

pma

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RIAA phono preamp with NFB, linear area full scale and deep saturation, burst signal, single shot. Red - preamp input, Blue - preamp output. The preamp has 36dB gain at 1kHz. There is no cartridge in the world to send 866mVpeak impulse.

RIAAphono_burst_lineararea_sm.png



RIAAphono_burst_deepoverload_sm.png
 
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amirm

amirm

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Would any competent turnable have any rumble serious enough to require filtering out in any case?
I have seen woofers on high-end LP systems at shows beat themselves to death with silent oscillations.
 

SoNic

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No. I have results and I can give a proof. I never use reasoning based on beliefs.
I don't doubt you have results. I tried it both ways and like it better the passive way...
Most of the implementations NFB are not great because is not that "trivial" like you said.
Throwing in an OpAmp is trivial. But not that great IMO.
 
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pma

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I don't doubt you have results. I tried it both ways and like it better the passive way...
Most of the implementations NFB are not great because is not that "trivial" like you said.
Throwing in an OpAmp is trivial. But not that great IMO.
This
E9A4F47F-D982-4C0E-B449-EB84EB11D617.png
But there is no reason why not to make the circuit with excellent overload recovery with the opamp as well. There is a lot of prejudice against opamps. It is all about choice and implementation.
 

SoNic

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I like J-FETs too on input stages, because they are fast and noiseless. But I think your design doesn't have enough open loop gain to be problematic. It works? yes. But is not trivial, you have to match those transistors to lower the THD. That i snot trivial to scale in manufacturing.

I like the OpAms. But I know their limitations, some of them are OK, some are just execrable.
I will date myself but I started working with LM101/301 and LM741... and what I use today is leaps and bounds better than those. And still I don't do high gain plus active filtering (like this application) in just one stage. It's just not going to sound good, even if static will measure great.

PS: However, not everyone uses those modern OpAms, not everyone uses proper circuit design, decoupling, etc...
 
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Jim Hagerman

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FWIW - here is my frequency response measurement of a Bugle3 using the inverse RIAA filter I designed...

b3-bode.png


My filter includes the 50kHz "Neuman" compensation, so there is no treble rise.
 

guenthi_r

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Own an Bugle2 long time ago.
Changed resistors & caps with matched pairs, also the OP-Amps to OPA1642/1656/1656 (only for MM).
The Bugle2 sounds very good, has a lean-back presentation (typical for passive RIAA-EQ), i like it.
The noise is a little bit on the high side, no worry about that.
Since the last 3 years the Bugle 2 is no longer my main preamp, was exchanged with the Rod Elliot´s P06 (low-impedance Version).
The P06 unites both worlds (active/passive-RIAA EQ), so i am happy with that.
Active and passive equalization both have their advantages and disadvantages. it's probably more a matter of taste.
Maybe i should reactivate the Bugle this weekend....?
However, the Bugle is an excellent Preamp, the passive EQ concept has its charm!
 
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VQR

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It would be good to redo. Thanks.
I can vouch I would want to see a redo of the Duo. I imagine even in your current tests it would be fine, but it's nice to have confirmation.
 

Jim Hagerman

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That doesn't seem to reflect that extra Neumann pole, did you stop including that?

It's in there. That's why the ASR measurements shows it to rise.

eq.png


Not everyone is a fan of the 3.18us corner, but I am, as explained in my paper above. As it turns out, that Neuman cutter head amplifier had a two-pole rolloff at 50kHz (think 2nd order Butterworth) using NFB. I add a single pole turn at 50kHz to partially compensate. The idea isn't so much about amplitude response, but rather phase (transient) correction. Yes, adding the zero in my phonostage EQ offers up a bit of "airiness" to playback, but more importantly it helps to retain the timing of upper harmonics. To me, this is the difference between hearing an actual violin (woody and flawed) instead of synthetic mimicry. Things like cymbals and piano seem to become slightly more realistic. IMHO.
 

cgallery

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It's in there. That's why the ASR measurements shows it to rise.

View attachment 274122

Not everyone is a fan of the 3.18us corner, but I am, as explained in my paper above. As it turns out, that Neuman cutter head amplifier had a two-pole rolloff at 50kHz (think 2nd order Butterworth) using NFB. I add a single pole turn at 50kHz to partially compensate. The idea isn't so much about amplitude response, but rather phase (transient) correction. Yes, adding the zero in my phonostage EQ offers up a bit of "airiness" to playback, but more importantly it helps to retain the timing of upper harmonics. To me, this is the difference between hearing an actual violin (woody and flawed) instead of synthetic mimicry. Things like cymbals and piano seem to become slightly more realistic. IMHO.

Does your reverse RIAA device also include that pole, and that is why the ASR graph shows it but your graph does not?
 
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AudioSceptic

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I have seen woofers on high-end LP systems at shows beat themselves to death with silent oscillations.
Yes, especially with ported speakers, but that's caused by warps and ripples in the vinyl not being filtered out by the arm-cartridge mass-compliance, not rumble, which strictly speaking is bearing noise and expected to be low in any decent TT.
 
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