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jpc2001

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Posts posted by jpc2001

    Solid State amps known to sound good with Klipsch

    in Solid State

    Posted

    I recently picked up a Sony STR-GX9ES. It drives Fortes very nicely! The sound is so much livelier than with the other amp I was using, I'm thinking that one was running up against its current limts (??) trying to drive the Fortes which are 4 ohms.

     

    It's a really neutral, clean sound. Lyrics are particularly easy to understand on this amp.

     

    FS: Pioneer SX-850 vintage receiver, Boston area

    in Garage Sale

    Posted · Edited by jpc2001

    Pioneer SX-850 stereo receiver. Good condition. Pretty face, minor knicks on the cab. I replaced transistors on the protection board, which fixed a problem with the protection relay opening sporadically. Also I changed out the bias pots and the power amps' input transistor pairs, and set the bias. I replaced tantalum coupling caps on the preamp with oversized electrolytics. (Tantalums sound bad.) This one is all running like it should now.

     

    It's clean inside, with no evidence of a major repair or rebuild. One of the output transistors is not original but it is a correct replacement.

     

    Built to last ten lifetimes. Has two pairs of output transistors per channel, which allows it to supply more current than its 65-wpc-into-8-ohms rating suggests.

     

    Asking $250.

     

    • Like 1

    near TOTL Sony STR-GX9 ES stereo receiver @ Boston CL

    in Alerts!

    Posted

    I bought this one last night. I will be selling a Pioneer SX-850 or a Rotel RB-970BX to make room for it.

     

    The Sony sounds NICE, holy heck it does!

     

    It's maybe better than my homebrew amps, to my chagrin. I've built several amps derived from the "Honey Badger" and "Wolverine" designs from diyaudio.com. These are very accurate amps, they simulate at 10ppm of distortion or less. This Sony gives them a real run for their money. I was A/Bing the Sony against the homebrews on a pair of Forte's. These are the first generation Forte's labeled 4 ohms impedance. The Sony sounds super clean and clear, muffled lyrics become easily audible. It's like a lyrics translator.

     

    This is the first factory-stock amp I've heard that could maybe beat the homebrews. A Pioneer SA-9500ii doesn't, the SX-850 doesn't, a Sanyo JCX-2600K didn't until it got turned into one of them, and the Rotel RB-970BX doesn't. Admittedly I haven't heard Macs or Krells or any tubes except a '60s Maggotbox console. I'm a cheapskate and fear bankruptcy if I dip my toe in those expensive waters.

     

    It's amazing how different two amps can sound, even when they both allegedly make very low distortion. Maybe tone differences are in play, with tone controls not centering perfectly. I sort of suspect the Sony is cheating and overemphasizing the bass a bit. The bass is maybe a little too solid. It would be interesting to measure.

    Preferred Repair Techs

    in Solid State

    Posted

    I do repairs in the Boston area, specializing in vintage solid state amps and preamps. I can also modify electronics to reduce noise and distortion in many cases. It can be made to work better than new.

     

    Usually I buy broken items and sell working items, but this model has led me to accumulate too much stuff that I don't want to sell. So I'm considering a fee-for-repair-service model. This isn't my real job, it's just a hobby; time scales involved may reflect that.

    • Like 1

    Albany Furniture Heresies

    in Alerts!

    Posted · Edited by jpc2001

    Albany, NY.

     

    Someone local contact him.

     

    Maybe $ 50 / pair.

     

    Or $ 500.

     

     

     

     

    That's my thinking. I would definitely let the seller name a price first. As the NY lotto ads say: hey, you never know!

     

    I'm in Boston, it's far enough from Albany that Google maps directions offers me quotes on flights. :rolleyes:  Otherwise I'd be in touch with the seller. They look nice.

    • Like 1

    RI craigslist "Klipschorns"

    in Alerts!

    Posted

    Sorry, I didn't mean to imply that there's anything wrong with a Speakerlab K. I actually own a pair of homebrew khorn clones, they get daily play time and are not for sale.

     

    There's a certain kind of CL ad, describing any moldy old homebrew speaker that happens to have a triangular cross-section as a "Klipschorn". If these are Speakerlabs built under license from Klipsch, this ad would be the mildest example of the form. :)

    • Like 1

    Solid State amps known to sound good with Klipsch

    in Solid State

    Posted

    John, your observation is also echoed here by Lynn Olson:  http://www.nutshellhifi.com/library/tinyhistory2.html.  My ears also agree with that assessment.

     

    The first few years of SS amplifiers were rough ones, to say the least.  It also affected the design of loudspeakers of that era (except for Klipsch and a few others):

     

     

    Instead, [the early SS amplifiers of the 1960s] failed at the drop of a hat, and were so aggressive and harsh with Class AB crossover distortion and Transient Intermodulation Distortion (TIM) that an entire generation of "East Coast Sound" speakers became duller and duller to compensate.

     

    Fascinating theory, and totally believable!

     

    If a Klipsch speaker and the amp don't sound right, it's usually the amp making distortion or noise.

     

    I like DIY "Wolverine" amps designed by ostripper at diyaudio.com. It's a modern class AB design, making part-per-million THD, you can build one to hit 0.001% THD at any signal level and any audio frequency. The component count is low, you can build it small enough to retrofit it into vintage receivers and integrateds. They sound absolutely transparent on Klipschorns and KG 5.5's.

    Clipping question...

    in Technical/Restorations

    Posted

    Heh... I'm dumb enough to not know if my question was answered.

    If you have a speaker that is actively biamped and the amp (channel?) goes into clip mode.... do BOTH channels clip or since they have different signals, are they independent of each other and one channel could clip while the other not?

    Yes, when biamping, you might clip only one amplifier.

    There are two types of clipping. The amp can run out of volts (output driven all the way to the rail) or it can run out of amps (current limiting protection circuit kicks in).

    My understanding is that current limiting is worse: the amp output goes to high impedance from the speaker's point of view. If a reactive speaker has stored energy and the amp can't accept that energy back, it's gotta go somewhere, the speaker may produce big voltage excursions and big mechanical excursions.

    If you have a pair of Khorns, LaScala, (enter speaker) and play it in a stereo situation..... you can push the amp to far and clip the amp.

    Clipping the amp might fry the tweeter. (I'm sure I've clipped something during college yet my LaScalas keep on keeping on :emotion-21: )

    Change the game a bit....now you are biamping with an active in the middle.

    If you have excess signal input into the amp and it clips, would it be expected to clip both channels?

    Would it be reasonable that since there might be more energy in the bass half, the bass channel might clip (only) thereby saving the tweeter?

    If you cross low enough where the workload on each channel is a theoretical 50/50 split and the amp clips would you be just as apt to be clipping the tweeter channel?

    What brought this up?

    I was cleaning up around the house, preparing for company. Had some Elton John 60 birthday DVD playing (great show by the way). Decided to change. Put something in I've not listened to in several years.... Metallica Cunning Stunts DVD.

    Sound was a bit harder than Elton (duh!) and they had some explosions. If those explosions are full sound, then I really need to hook up my subs because I think they would shake the house and I love stuff like that.

    Anyways, it was that excess energy that got me wondering.

    Now I go back to preparing for company.

    Sent from my GT-I9300 using Tapatalk

    kg 5.5 price?

    in 2-Channel Home Audio

    Posted · Edited by jpc2001

    I bought a pair of KM-6s in summer 2013 for $100 in 8/10 condition. Those are the military PX version of the KG 5.5's, they're identical. THAT was a score. I got down there fast!

     

    My Khorn clones dig deeper but the KM-6s are very, very nice, detailed and uncolored all through the mids and highs. I don't really have a preference for one pair or the other. They are both special.

     

    I recapped the KM-6s with polypropylenes. They needed it, the old electrolytics were 15 or 20% off the nominal values.

    Tech service, eastern MA

    in Garage Sale

    Posted

    Degreed electrical engineer, I can fix and tune up amps and preamps. I could estimate repairs for you, or trade working gear for your non-working gear.

     

    I have some repaired units for sale:

     - Onkyo TX-4500 mkII receiver, 65wpc. Clean in and out. I replaced the protection relay and cleaned all pots and switches with DeOxit. It looks factory fresh inside. $100.

     - Kenwood KR-5030, 65wpc. Coming soon, it's awaiting a relay. This one has the "triac" mod, this is a permanent fix for the unreliable OEM power switch. The front face is quite clean; the inside is clean; the top cover has some corrosion at the rear edge. $90.

     

    It's also possible to reduce noise and distortion to better-than-new levels on some older gear, ask about that.

     

    Cheers

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