Antique Sound Lab (ASL) Wave AV-8 tube amps w/ Auricaps and more

Discussion in 'Hardware Classifieds' started by Saurav, Aug 16, 2003.

  1. Saurav

    Saurav Cinematographer

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    If you're reading this, you probably know what these amps are. I have the version with the tube cage and the IEC socket/removable power cord. I've made the following modifications/upgrades to these amps:

    * Auricap coupling caps
    * Panasonic TSHA/TSHB power supply caps
    * Upgraded cathode bypass caps and added mylar bypass caps
    * Upgraded RCA connector
    * Replaced most resistors
    * Reverse Recovery Spike Filter (RRSF) (aka "HV Snubber", design borrowed from discussions on the Bottlehead forum)
    * Replaced rectifier diodes with UF4007
    * Changed routing for heater grounds to keep them further away from signal grounds
    * Teflon tape on tubes to damp microphonics

    The following "under the hood" image shows the upgrades. The large yellow caps are the Auricaps. The black electrolytics are the Panasonic PS caps. The two large resistors and ceramic caps near the top are the RRSF, and the small yellow caps are the mylar bypasses on the cathode bias caps:

    [​IMG]

    The teflon tape on the tubes:

    [​IMG]

    A shot with the tube cage on:

    [​IMG]

    And finally, the rear panel showing the IEC socket, speaker connectors and the RCA connector I added:

    [​IMG]

    I bought the amps new from a dealer, and they've been in a non-smoking pet-free environment the whole time. They sound great in stock form, and the upgrades add a little more to their performance. These were my introduction to tube amps, and the only reason I'm selling them is because I was inspired to try building my own.

    Price is $250 + shipping o.b.o. PayPal is preferred, money orders and personal checks are accepted. I've shipped lots of audio gear including turntables, so rest assured that these will be packed carefully.

    Please respond to this thread or email me if interested.

    Thanks for looking,

    Saurav
     
  2. Saurav

    Saurav Cinematographer

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    Shameless bump [​IMG]
     
  3. Saurav

    Saurav Cinematographer

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    Bump again.
     
  4. Doug_B

    Doug_B Screenwriter

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    Saurav,

    This intrigues me, but I know nothing about tube-based amps (other than what I've read here and there on forums for the past 2 years). I have been interested in trying out tubes for my system for a while (beyond the Ah! 4000 CDP that I have), but I've been thinking more from the perspective of a pre-amp. I don't think a tube amp will work in my system because:

    1) I don't think my speakers are efficient enough (supposedly 88db - Soundline Audio SL3 ribbons, based on the BG RD50 ribbon), plus they probably are too low impedence-wise (but see potential workaround below).

    2) I use my audio system for both music and home theater (music more, though [​IMG] ). The quest for a tube-based pre-amp with an HT bypass would allow the integration of such a pre-amp. I am dubious as to whether or not I can come up with a workable / convenient architecture that would include the ASL or any other tube-based amp, assuming that they would not be adequate for the HT part of the equation.

    I'd like to get your feedback as to whether or not you think I can make these work in my system (see sig link for full equipment - also see this link for the 2 channel portion schematic of my overall system).

    One idea I have that may make these amps workable in my system: the ribbon portion of my mains are a purely resistive load (I believe 4 ohms), with a crossover to the 8" woofer at 250 Hz. I have 2 sets of terminals for each speaker to allow for biamping, so maybe the ASLs can be used for the ribbons exclusively (even though I've heard that tubes can be good for bass; in any case, I use an ICBM and cross the bass over to my sub, even for music, because bass response from the location of my mains is not good).

    I'm curious how the mods you made changed the sound of the stock ASLs (as I've had a chance to read a couple of "reviews" tonight) and your opinion (based on experience, others, guesswork, etc.) on how they'd work with ribbon speakers. Any other relevant feedback would be appreciated.

    Thanks.

    Doug
     
  5. Saurav

    Saurav Cinematographer

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    Hi Doug,

    Lots of good questions [​IMG]

    > 1) I don't think my speakers are efficient enough (supposedly 88db - Soundline Audio SL3 ribbons, based on the BG RD50 ribbon),

    I've used my ASL Waves with 88dB speakers, the GR Research Paradox 1s. My room is 15'x20', and as long as I wasn't trying to hit 90dB average SPL playing Van Halen, the combination worked fine. Dynamics weren't as good as they could have been (this is certainly not an optimal combination, and a 51/4" woofer can only produce so much dynamics, no matter how much power you feed it), but they were fine for most of my music.

    > plus they probably are too low impedence-wise (but see potential workaround below).

    That's important, my speakers were 8 ohms nominal and 7.2 ohms minimum, which is really flat. The ASLs only have an 8 ohm speaker output, so I'm not sure how they'd work with your ribbons. I do know of people bi-amping with the Waves on top though.

    > I am dubious as to whether or not I can come up with a workable / convenient architecture that would include the ASL or any other tube-based amp, assuming that they would not be adequate for the HT part of the equation.

    That depends totally on the speakers. I now have 96dB speakers, and I can assure you that the ASL amp will drive them to any sane volume levels. I've reached 90dB with a 3W amp on these speakers.

    BTW, your website link gave me an error.

    > I'd like to get your feedback as to whether or not you think I can make these work in my system (see sig link for full equipment - also see this link for the 2 channel portion schematic of my overall system).

    I think you could make it work, but honestly, I don't know if this would be the best option for you. Especially if the HT side of things are important and you plan to run them full-range.

    > One idea I have that may make these amps workable in my system

    I've kinda-biamped my system with the ASL amps too, by adding a passive high-pass filter before them. That certainly seemed to help (the amps a little, and mainly my speakers), everything was a little more relaxed and breathed a little more freely, so to speak.

    > I'm curious how the mods you made changed the sound of the stock ASLs

    If you're looking through Audio Asylum, you'll find reviews of the Auricap mod on these amps. Several people have upgraded the coupling caps. In my opinion, all of the mods made the sound progressively more refined, with some mods having a bigger effect than others. Treble became smoother, and the overall sound became cleaner (like the proverbial veil that's always being lifted away), it sounded like some low-level hash/grunge was being progressively reduced. The amps started handling complex passages better, with less confusion/congestion in the sound.

    All this is relative to stock though. At their price point, I haven't heard any $200 amp (SS or tube) that sound as sweet as these, and with the mods, I think they hold their own with stuff quite a bit more expensive.

    > and your opinion (based on experience, others, guesswork, etc.) on how they'd work with ribbon speakers.

    I have no experience with ribbon drivers at all, and I'd rather not speculate.

    > Any other relevant feedback would be appreciated.

    You could try and find out the sensitivity and impedance curve of your ribbon drivers. If the sensitivity is reasonable and the impedance is fairly flat (the 4 ohms might work as long as it doesn't jump all over the map), these amps might work for you. But, like I said, I don't have any first-hand experience with ribbons, and so this would be an experiment, which is why I said that it might not be your best option (depending on how much money you're willing to spend on experiments). If it works though, I think you could end up with something really special.

    Hope that helps.

    Saurav
     
  6. Doug_B

    Doug_B Screenwriter

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    Saurav,

    Thanks for the feedback. Don't know which link didn't work for you (maybe both, since both are on the same site), so I'll embed the image of the schematic and see if that works for you:

    ***Edited image out***

    I'll contact the Soundline Audio owners and see what they say. I would think that the best possibility would be to drive only the ribbons (I'm fairly sure that the 4 ohm load is fairly constant - a simple resistive load), which as you say would require a high pass filter (or crossover) before them.

    Am I correct in assuming that a tube-based amp typically shows more of the tube flavor in the final sound than a tube-based pre-amp (if one can even generalize here)?

    As for cost, I was also thinking of going the bottlehead pre-amp kit route, just to see if I would like tubes. I believe this would cost a bit more than your amps, although it's been quite a while since I've read up on the bottlehead stuff.

    Thanks.

    Doug
     
  7. Saurav

    Saurav Cinematographer

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    > Am I correct in assuming that a tube-based amp typically shows more of the tube flavor in the final sound than a tube-based pre-amp (if one can even generalize here)?

    Depends, and you'll get varying responses to that. It's true that tubes and transistors have a different distortion spectrum (i.e. the way the distortion amounts are distributed across the different harmonics), and if that's what you're looking for, you'll get it from a preamp. But some people will tell you that the true "tube sound" comes from the way tubes interact with speakers, and for that you'll need a tube amp, even a hybrid won't be good enough.

    > As for cost, I was also thinking of going the bottlehead pre-amp kit route, just to see if I would like tubes.

    And I would very enthusiastically encourage you to try that. The Foreplay is (or was, last time I saw) $150 for the basic kit, $300 with all Bottlehead upgrades, and of course you can spend more money on exotic parts if you like. I've built the Foreplay, and it was the most fun I've had in a long time.
     
  8. Saurav

    Saurav Cinematographer

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    The amps are now sold.
     

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