Audio Flynn Posted January 25, 2003 Share Posted January 25, 2003 Background ---------- I am very open to new technology. For Example I talked my boss into buying a 425 megabyte Fujitsu hard drive for a CAD software experiement in 1985 for $ 16,000. I like to be "on the edge". In reading from various sources I became very interested in the pulse width modulation(PWM) concept as a basis for an amplifier design. After acquiring the Chorus IIs( to create a dedicated 2 channel set up in the living room), I was still finding the musicality to be a lacking more than I expected away from the TV and digital preamp. At only certain SPLs did I feel the Chorus IIs were sweet sounding. At most SPLs the sound was fatiguing to the point of disappointment. All brand name PWM amplifiers I read about were very expensive and the normal unnecessary 100 + watts. Still doing research on understanding where I would go in the vintage tube objective, I decided to take LEOK up on the offer to buy the P6D stereo amplifier based upon the Tripath IC from his company Waltham Integration. In my written discussions with LEOK the amplifier was described as a maximum 8 WPC design with gain control that could be run off of the tape monitor of an intergrated amp or receiver. One set of inputs and one set of outputs in a svelte box a little bigger than a large paperback book. An outboard AC to DC converter was included. PWM amps are very efficient and produce very little waste heat; the box does not require any venting. Reviewer History ---------------- Since my tube experience has been guitar amplifiers and vintage Motorola consoles, it has been nearly 20 years since I have critically listened to tubes in a home environment. Some forum members may know I spent several thousand hours listening to live music both accoustic(nearfield and amplified) and electric from 1976-1983 as an ameteur Sound Engineer. SS amps I have listened to in the past 20 years are including but not limited to Sherwood Newcastle, Bryston, Rotel, Denon, Marantz, Phase Linear and Hafler. Klipsch I have listened to are(first to most recent over 26 years) are LaScalas, Heresey, KSB 3.1, RB-5, and Chorus II. Music used for evaluation ------------------------- Wanting to provide an objective review in as much detail as possible given the time LEOK spent corresponding with me and of course designing the amp; I felt music selection was important. Since I have not had a vinyl front end in operation since 1992(Dual 510 and Ortofon), I wanted to find CDs from different companies that were recorded and mastered with minimal effects or compression. Rock and Roll recorded for "car stereo" listening audiences were avoided. Final CD selections -JS Bach Organ Chorales,Wolfgang Rubsam, Naxos -Tchaikovsky no. 4, Colorado Symphony, Naxos -Sofie Van Otter meets Elvis Costello, For the Stars, Deutch Gramophone -Crosby Stills and Nash, first Album, Atlantic -Crosby Nash, Another Stoney Evening, Arista -Neil Young, Silver and Gold, Reprise -Eric Clapton, One more Car one more rider, Reprise -Patricia Barber, Companion, Blue Note I listened to allot of guitars and vacal harmony in my youth and have good memory of the experiences. Organ I hear 2-3 times a month at church. My daughter was drum section leader of the local HS marching band. TAS reviewed the Tchaikovsky CD very highly. Who, Deep Purple, New Age music, synthesisers and other numerous selections were ommitted from final review session due to poor mastering or unfamialrity to a musician's or instrument's "real" sound sujectively percived by myself. This is the method to the maddness of the CD selections. Amplifier "voicing" observations -------------------------------- I was not very surprised by the change from my SS amps. The britttleness and fatigue I experienced were immediately eliminated with the P6D. This was a confirmation that P6D had very low distortion under 2 watts; where poorly executed SS can be 3-5 % or more. From the little low mass P6D bass firmness seemd quite adequate. No need for hefty transformers in this amp design. This aspect is exceptionally surprising for a 40 ish audiophile on a limited budget. "Neutral and transparent" are the first terms that come to mind. The P6D does not appear to accentuate any particular frequencies. Not sure if any part of the audio band is deempasised, muddy or sluggish; this I find difficult to assess. Rock concert SPLs are not the intention of the amp. Pushing the amp too hard dimminished the transparency. A song by CSN named "Guinnevere" is respected by LEOK and I for the vocal harmony and Martin Guitars. The Version on "Another Stoney Evening"(ASE) states the recording was done live(1971) in a minimalist set up using Shure SM -57 mics, United Audio tube console, and #M 8 track machine(Wally Heider equipment recorded by Bill Halverson, remixed 1997). CSN version is nice but easily detected to be overcompressed through the P6D. ASE version was very natural sounding to me, although the vocals are mixed to be more prominent than the guitars. The P6D allowed an open soudstage for the vocals. I picked the Eric Clapton for the drums , bass and electric guitar. From disc one the songs "Reptile" and "She's Gone" are mixed very well and the P6D reproduced the kick drum to the high hat effortlessly. EC blues vocal gets better with age; this CD and the P6D reproduce it very well. I will describe my experiences with the other CDs in a day or two. As an old journalism student I wanted to be thorough with this very unique component from a valuable forum contributor. If you are still reading thanks for your patience. Rick LEOK, Please comment! Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted January 25, 2003 Share Posted January 25, 2003 Nice job on the review. You need to run some comparisons with good tube options too. Would be a nice comparison. Looking forward to more listening observations and thoughts. I was sent one of these PWM boards to photograph for a client and I could not believe the size. IT is literally the size of a credit card! Amazing stuff. Not totally sold on the sound but it's amazing nonetheless. kh Quote Link to comment Share on other sites More sharing options...
leok Posted January 25, 2003 Share Posted January 25, 2003 audio, I've refered to the P6D often in my posts (as the Tripath design), but this is the first time there has been an alternate view of this same amp. I'm pleased you have been generous enough to share your perceptions of this relatively new technology with members of this site. There is nothing in your report that would indicate that you misunderstand the amp or its intended application. I find that my impressions are very close to yours. As to the implementation. Kelly, was the pc assembly you saw made by Tripath or Waltham Integration? I ask because, the W.I. assembly is my own pc design and uses higher grade parts and employs the DC input circuit I posted here last summer rather than the cap coupled circuit employed by Tripath on their demo board. The W.I on-board power supply is many times bigger than the Tripath version. Finally, the W.I. packaging includes RF filtering on all input , output, and power. The intent of the P6D is to implement the Tripath TA1101B in a manner that is optimized for Klipsch Horn speakers. I was convinced that the low distortion at low power specifications for the Tripath TA1101B, if properly realized, would be effective. The TA1101B has been replaced, by Tripath, by the TA2024. I too look foreward to audio's future comparisons with tube amps. I believe tubes can be an improvement over the P6D sound, but not all tube implementations do sound better. Many fall short. With the P6D, audio flynn has a standard he can use to be sure his tube selection lives up to its potential. Also, for a quick 10 minute listen to something .. with too little time to warm up the tubes, the P6D can be treated like a transistor radio with near tube sound. Thanks, audio flynn leok Quote Link to comment Share on other sites More sharing options...
Deang Posted January 25, 2003 Share Posted January 25, 2003 Leo has mail from The Rookie. Quote Link to comment Share on other sites More sharing options...
AndyKubicki Posted January 25, 2003 Share Posted January 25, 2003 Guys, where can we read more about this design? Quote Link to comment Share on other sites More sharing options...
Audio Flynn Posted January 25, 2003 Author Share Posted January 25, 2003 Mobile, Thanks. Your perceptions set a high standard for thoroughness of equipment reviews; I just try to keep pace. I certainly would like to follow up with some tube comparrissons. I am bidding on a NON Eico or Scott right now. Do not want to draw attention to the auction because it loos like an interesting "off brand". For a Scott or Eico they seem to get to $ 200(some much higher) plus shipping and insurance; so about $ 250 or more before I can drive it up to Craig. Wish I thought of tube investigations a few years ago. The interest seems quite high now. ------------------------------------------------------------ Can some of you vinyl officionados comment on my CD selection? ------------------------------------------------------------- I thought this was an extremely important part of the review. The MSB Link is a nice DAC but it cannot enhance a bad CD. I feel strongly NAXOS, DG and BLUE NOTE are recorded and mastered to CD far more carefully in an audiophile sense than popular music. I have only heard a good orchestra live 6-7 times in my life. It is difficult to comment on classical CDs so I rely on TAS and Stereophile reviews to assist in deciding on good sonics in this genre. Chesky CDs from Sara K. and The Coryells make for good auditioning material as well. LEOK, I am glad the review appears thorough and coincides with some of your observations. Rick Quote Link to comment Share on other sites More sharing options...
Audio Flynn Posted January 25, 2003 Author Share Posted January 25, 2003 Andy, Leo sent me some .pdf files. For documentation control I would think it would be best to get it from Leo directly, in case he has more details to publish. I am sure he will make them avialiable. Quote Link to comment Share on other sites More sharing options...
leok Posted January 25, 2003 Share Posted January 25, 2003 Andy, I'll send some material directly. However, with the exception of the dc input, the design is essentially the application circuit on the Tripath TA2024 chip, which is on the Tripath (http://www.tripath.com) website. leok Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted January 25, 2003 Share Posted January 25, 2003 PWM Module - LC Audio Version Leo and others, no, the design I saw was not near as developed as the one you are working on. It is was being marketed by LC Audio and was a much higher wattage, thus was more grainy and suitable for a different set of application, although the watt hungry crowd was excited. For others not aware of the basic thing we are talking about, here is a collage of the LC Audio version (these are not my pics but I made the site). Though this is not the same thing Rick is auditioning by any means. But the size of these PWM modules is amazing and considering that over 200-600w is available depending on configuration is beneficial to many. Of course, Leo's version appears to be far more geared toward quality amplification. I would be interested in hearing one of the Leo's units just to compare. Kevin didnt seem to think the Tripath equaled the relaxed nature of good tubes but others are overjoyed. kh Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 25, 2003 Share Posted January 25, 2003 Kelly you must of run out the door right after this post !! Trying to give you a ring !! Quote Link to comment Share on other sites More sharing options...
leok Posted January 25, 2003 Share Posted January 25, 2003 I just remembered that I posted the schematic and a descritption at (http://home.attbi.com/~k3c1/wi_home.html). The one Kelly has a picture of is another chip .. one of the more powerful in the Tripath line. I think for use with horn speakers it would be noisier and have more distortion than the TA2024. Kelly, I can loan you a prototype. I have to wire it up .. it will take a couple of weeks (there are several tedious mods). leok Quote Link to comment Share on other sites More sharing options...
jnorv Posted January 25, 2003 Share Posted January 25, 2003 I have ben trying to get some infor on buying a Tripath 2020 eval board but can't seem to get their attention. And I live in San Jose. Have any of you recently contacted Tripath with good results? JIm N Quote Link to comment Share on other sites More sharing options...
leok Posted January 25, 2003 Share Posted January 25, 2003 I always went through a local rep .. nothing direct. Hopefully they list reps. on the web site. leok Quote Link to comment Share on other sites More sharing options...
jnorv Posted January 26, 2003 Share Posted January 26, 2003 Maybe they have downsized since you last dealt with them. They list reps in Taipei, Tokyo and San Jose. Graham, the VP of sales, seems to be unavailbale. Jim N Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 26, 2003 Share Posted January 26, 2003 Leo, You ever futzed with a Gain card Clone circuit? Quote Link to comment Share on other sites More sharing options...
leok Posted January 26, 2003 Share Posted January 26, 2003 Mike, I don't know anything about it. What is it? leok Quote Link to comment Share on other sites More sharing options...
leok Posted January 26, 2003 Share Posted January 26, 2003 jnorv, I wouldn't expect a vp of sales, in any company, to respond to anything. "vp of sales" to me says "ivory tower." Who knows what those people do? I do a lot of work with the semiconductor business, and unless you're talking 10,000/year, you're not on the radar (but that's why the stuff costs a few $). You have to hunt. I know my old contact for Tripath parts is no longer a Tripath rep. So, If I do a spin of the board, using the TA2024, I'll have to find a stash of chips on some distributor's shelf. leok Quote Link to comment Share on other sites More sharing options...
Chris Robinson Posted January 26, 2003 Share Posted January 26, 2003 What does a VP of Sales do? He makes my life frikkin' miserable Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted January 26, 2003 Share Posted January 26, 2003 Indeed. Heh... For those interested in the Gaincard, here is the 47 Labs version. http://www.sakurasystems.com/products/47amp.html There have been a number of DIY attempts to duplicate the Gaincard. One such version is simply entitled "The Gaincard Clone." A search via Google will bring some info. Check out the Sakura page above. kh ps- Leo, I dropped you a mail earlier Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 26, 2003 Share Posted January 26, 2003 Geezus, that PitTracer is about a spendy bastard! At least they throw in the nice option of a power supply. Quote Link to comment Share on other sites More sharing options...
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