B1 Buffer Preamp

124

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  • zingo
    zingo Posts: 11,258
    edited February 2013
    And it looks like the output impedance of the Squeezebox Touch at analog outputs is about 600ohm from what I could find.
    Jake
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  • FTGV
    FTGV Posts: 3,649
    edited February 2013
    zingo wrote: »
    14Kohm at the RCA jacks
    Then you might try adding some series resistance at the input of the amp to give some attenuation.
    zingo wrote: »
    And it looks like the output impedance of the Squeezebox Touch at analog outputs is about 600ohm from what I could find.
    Which is fine,I assume the pot is on the input side of the buffer.
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  • zingo
    zingo Posts: 11,258
    edited February 2013
    I thought about that, but what attenuation would you suggest Fred?
    Jake
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  • FTGV
    FTGV Posts: 3,649
    edited February 2013
    Experiment .If the input impedance is actually 14k then 7k in series will give a 3 db reduction in signal,and 14k will cut the signal in half( -6db) .Adjust to peference.
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  • zingo
    zingo Posts: 11,258
    edited February 2013
    There might be space for a resistor behind the RCA jacks on the back panel of the speakers. Thanks for the idea Fred and it shouldn't be too hard to find an audio grade 14K resistor. I don't like the idea of another componey in the signal path, but I won't know until I try it.
    Jake
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  • FTGV
    FTGV Posts: 3,649
    edited February 2013
    Are you sure you want to start with a full -6db of attenuation?Anyway IMO a single 1 % metal film resistor should be sonically benign.
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  • Face
    Face Posts: 14,340
    edited February 2013
    Extremely transparent resistors. http://www.partsconnexion.com/resistors_vishay_var.html
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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  • FTGV
    FTGV Posts: 3,649
    edited February 2013
    And for those with only marginal OCD:biggrin: http://www.partsconnexion.com/resistors_caddock_mk.html and for those without.http://www.partsconnexion.com/resistors_holco.html
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  • zingo
    zingo Posts: 11,258
    edited February 2013
    Let me see where my wallet puts my level of OCD... :mrgreen:
    Jake
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  • zingo
    zingo Posts: 11,258
    edited February 2013
    The B1 in a sheet metal chassis for function, not form. It sounds great, but as my brother commented; "That's ugly".

    photo.JPG
    Jake
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  • zingo
    zingo Posts: 11,258
    edited February 2013
    photo (1).JPG
    Jake
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  • zingo
    zingo Posts: 11,258
    edited February 2013
    photo (2).JPG


    Changed out the caps in my B1 last night for red, film Audiophiler ones from China. I'm not expecting much, but so far they sound like the original ones without any hours on them.
    Jake
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    Just ordered some 25k Caddock MP925 non-inductive resistors to try in a few places and see what sounds best when lowering the output a little.

    Thanks for the suggestion guys!
    Jake
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    Soldered the 25K resistors in front of the 25K attenuator, but didn't notice any decrease in overall volume. Interestingly, the sound may have sharpened up a little, but I would guess that would be from the source now seeing twice the input impedance then it previously saw. I'll keep working on this...
    Jake
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  • SCompRacer
    SCompRacer Posts: 8,505
    edited March 2013
    Nekkid Z-foil up close....from a thread at diyaudio, taken with a polarized light AM4113ZT-A Dino-lite usb cam. $ Ka-ching $.
    Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ * Signature Series Sonore Music Server w/Deux PS * Roon * Gustard R26 DAC / Singxer SU-6 DDC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 *
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    Sexy! Mine don't look as good, but they do sound good!

    $(KGrHqF,!nkE63U,eSimBO8k!lGqGQ~~60_35.JPG
    Jake
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    zingo wrote: »
    Soldered the 25K resistors in front of the 25K attenuator, but didn't notice any decrease in overall volume. Interestingly, the sound may have sharpened up a little, but I would guess that would be from the source now seeing twice the input impedance then it previously saw. I'll keep working on this...

    After doing some A/B testing, there is a small volume reduction having the 25K resistors in front of the 25K attenuator that was not discernible without a direct comparison.
    Jake
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    I was doing some listening over the weekend comparing the B1 with SMD stepped attenuator to my Luminous Audio Axiom II passive which uses an ALPS blue velvet pot. As I have 7ft ICs to run to my speakers, I thought an active buffer might benefit the system in order to drive those long ICs, and help with any impedance issues between the Squeezebox and the speakers.

    The Axiom is very pleasant and creates a nicely balanced image and sound; The sound stage is very centered. The pot is a little unbalanced at low levels, but not during regular listening. The B1 is a little more dynamic, but splits out the instruments more with a very defined sound stage that places the musicians in specific spaces. While listening to Rebecca Pidgeon, the B1 placed her to the left of center and her supporting violin to right of center. This is probably a more accurate presentation of the music, but the Axiom centers her voice with the violin behind her and to the right. The B1 feels more like a stage performance, but the Axiom is easier to listen to for normal listening.

    I then placed the B1 at the output of the Axiom, and the result sounded exactly like the B1 alone. To me, this means the the B1 is leaving its own signature on the signal, whether good or bad to your ear, which the Axiom with single pot is doing a better job of simply attenuating and passing the signal.


    Just a few observations...
    Jake
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  • Face
    Face Posts: 14,340
    edited March 2013
    Upgrade the B1's caps and this won't be as much of an issue, if an issue at all.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    Are you saying my red "Audiophiler" caps aren't the best available?!? :)
    Jake
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  • Face
    Face Posts: 14,340
    edited March 2013
    No, not at all. :)
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    Recommendation for caps in a smaller enclosure? Might mount the B1 in this passive preamp. :cheesygrin:

    I know the Obbligato makes a smaller body film cap (.8" tall for 10uf). If I can't find anything else I'll probably go with the ESAs (1.8" tall for 10uf), so I'll have to measure and see how much space I have.

    2.jpg
    2.jpg 79.8K
    Jake
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  • EndersShadow
    EndersShadow Posts: 17,593
    edited March 2013
    zingo wrote: »
    Recommendation for caps in a smaller enclosure? Might mount the B1 in this passive preamp. :cheesygrin:

    I know the Obbligato makes a smaller body film cap (.8" tall for 10uf). If I can't find anything else I'll probably go with the ESAs (1.8" tall for 10uf), so I'll have to measure and see how much space I have.

    2.jpg

    What enclosure is THAT? Its DARNED SEXY!!!!!!!
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    EndersShadow wrote: »
    What enclosure is THAT? Its DARNED SEXY!!!!!!!

    Secret secret for now...
    Jake
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  • Face
    Face Posts: 14,340
    edited March 2013
    http://www.partsconnexion.com/capacitor_film_claritycap_mr400v.html
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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  • pitdogg2
    pitdogg2 Posts: 25,569
    edited March 2013
    Jake in the post 101 picture the interconnects on the right with red and white on the RCA's look just like my cheap Phillips interconnect i have...Is that what they are? Actually they are pretty good for 6.00 interconnects:wink:
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    Thanks but a little more than I want to spend; I think the ESA is my top for Clarity Caps.

    Ever tried or heard ANSAR Supersound film caps?
    Jake
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    pitdogg2 wrote: »
    Jake in the post 101 picture the interconnects on the right with red and white on the RCA's look just like my cheap Phillips interconnect i have...Is that what they are? Actually they are pretty good for 6.00 interconnects:wink:

    They are the Phillips ICs, and I agree that you can't do better for the money. However, they do run from my Blu-ray player, so I'm not as concerned with IC quality as what runs from my Squeezebox. The other ICs are Luminous Audio custom copper coaxial wire with silver locking plugs (Squeezebox to preamp) and DH Labs White Lightening with Luminous Audio silver locking plugs (preamp to speakers).
    Jake
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  • Face
    Face Posts: 14,340
    edited March 2013
    Sorry, I haven't heard ANSAR caps.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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  • SCompRacer
    SCompRacer Posts: 8,505
    edited March 2013
    zingo wrote: »
    Thanks but a little more than I want to spend; I think the ESA is my top for Clarity Caps.

    Ever tried or heard ANSAR Supersound film caps?

    How about DynamiCaps? 10uf, 1.43 x 1.64 ~$45.
    Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ * Signature Series Sonore Music Server w/Deux PS * Roon * Gustard R26 DAC / Singxer SU-6 DDC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 *
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