killer clown Posted October 22, 2011 Share Posted October 22, 2011 Forum poulace,I am considering adding a class A or A/B tube buffer between my Denon 2930 ci and my Denon AVR 5600.Investment ceiling to achieve this goal is 1200.00 U.S..What I am seeking is a front to back schematic and/or diy kit to construct an integrated tube buffer.T the buffer/buffers should have o dB gain,thd of less than .05,capability of impedence matching,broad bandwith,and a signal coloration that is neither clinical nor muddy.I would like suggestions that are based on the experience and knowledgable.Thanks,K.C. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted October 22, 2011 Share Posted October 22, 2011 What are you hoping to accomplish by using the buffer? Also, please clarify what you mean by "integrated" tube buffer. The goals you have stated are technically possible, but I question whether it's worth the trouble. Quote Link to comment Share on other sites More sharing options...
Marvel Posted October 22, 2011 Share Posted October 22, 2011 You could try the Decware ZBOX... http://www.decware.com/newsite/zbox.htm Bruce Quote Link to comment Share on other sites More sharing options...
djk Posted October 22, 2011 Share Posted October 22, 2011 This PAIA design allows the user to control the operating point of the tube (changing its sound), and pan the output between solid state, tube only, or anywhere inbetween. http://www.paia.com/ProdArticles/tubesnd.htm http://www.paia.com/manuals/docs/9305-tubehead-schematic.pdf http://www.paia.com/manuals/docs/9305-tubeplankit-manual.pdf Quote Link to comment Share on other sites More sharing options...
killer clown Posted October 22, 2011 Author Share Posted October 22, 2011 My intensions are to introduce tube sound between the DACs of the CD player and the preamp,as well as impedence match the two comonents.I am sorry I was not clear on the integrated statement.What I meant was I want is a suggestion for a schematic or diy kit using both tubes and solid state for a 0dB gain.K.C. Quote Link to comment Share on other sites More sharing options...
killer clown Posted October 22, 2011 Author Share Posted October 22, 2011 I looked over the Decware,not quite what I was looking for,and the PAIA looks more to my expectations.Keep the suggetions coming.I am going to look over the PAIA again to assess the pro and cons.Thanks for the help so far.K.C. Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted October 23, 2011 Share Posted October 23, 2011 Just out of curiosity, what is the output/input impedance relationship between these components right now, and is it possible, if you are interested in the potential effects of valves in your system, that a tube-based linestage preamp might be something worth investigating? Quote Link to comment Share on other sites More sharing options...
killer clown Posted October 23, 2011 Author Share Posted October 23, 2011 The CD player has as output impedence of 470k ohms and the preamp an input impedence of 47k ohms.I want to keep the Denon 5600 preamp and amp because they are (to my ear) exceptional audio equipment.I have been looking over Glasswares offerings and TubeCad's interpretations of these buffers.Joe's descriptions of these buffer designs are very insightful.K.C. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted October 23, 2011 Share Posted October 23, 2011 The CD player has as output impedence of 470k ohms and the preamp an input impedence of 47k ohms.I want to keep the Denon 5600 preamp and amp because they are (to my ear) exceptional audio equipment.I have been looking over Glasswares offerings and TubeCad's interpretations of these buffers.Joe's descriptions of these buffer designs are very insightful.K.C. There's no way that the CD player output impedance can be that high! Typically, the values are a few hundred ohms. Even if the output impedance of the CD player is very high, say 1k, there is not going to be any interface problem when driving the 47k load at the preamp's input. Quote Link to comment Share on other sites More sharing options...
killer clown Posted October 23, 2011 Author Share Posted October 23, 2011 My memory failed me,not the first time.I looked at the CD players specs as listed by Denon and it states the analogue outpt impedence as 10k ohms.Thanks for the heads up tube fanatic.K.C. Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted October 24, 2011 Share Posted October 24, 2011 Your CD player has an output Z (impedance) of 470k ohms?? Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted October 24, 2011 Share Posted October 24, 2011 Oh. That sounds more in keeping with what I would expect. The general rule is that a source output impedance should be 10 times less than that of the load it's driving. As a personal and totally subjective approach, I would want as little as possible in the way of extra circuitry (including the inherent impedances and potential Miller capacitance effects related to it -- all of which can potentially impose signal degredation) between my sources and preamp. A good valve line stage, though, might be an idea to try. Anyway, experiment! Quote Link to comment Share on other sites More sharing options...
killer clown Posted October 24, 2011 Author Share Posted October 24, 2011 I had read the 1:10 in my meanderings of the Internet.Correct me if I am wrong,I currently have a Z ratio of 1:4.7?Erik,those very problems you have brought to light are those issues that I hope to avoid.I know not introducing the buffer into the signal path will eliminate the issues.That being said,I have a couriousity of introducing valves into the line.Hypothetically,what design would allow me to accomplish my goals?Thanks,K.C. Quote Link to comment Share on other sites More sharing options...
djk Posted October 24, 2011 Share Posted October 24, 2011 The Denon 2930ci is rated to drive 2VRMS into a 10KΩ load. The actual output impedance is not stated, but is probably less than 100Ω. Quote Link to comment Share on other sites More sharing options...
Ski Bum Posted October 24, 2011 Share Posted October 24, 2011 Erik,those very problems you have brought to light are those issues that I hope to avoid I would second what Erik said. While I have tried a few tube buffer stages, including the Decware mentioned above, none really excited me enough to actually purchase them. Tube amplifiers driving speakers, however, will have the 'tube sound', regardless of what's upstream. In this case, the 'tube sound' is largely a result of how the amp's output trannys and high output impedance interact with your speakers. Putting a tube line stage in the mix won't replicate that. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted October 24, 2011 Share Posted October 24, 2011 I bought a Yaqin CD-1 tube buffer. It uses just 1 12 ax-7 tube. So it is simple. One tube with matched triodes is all that is required. I sent the buffer up to Craig at NosValves and he beefed up the power supply and recapped the thing with all Auricaps in the audio path and installed audiophile resistors. It is a perfect finish for my BenchMark DAC-1 USB. It changes flat edgey sounding digital recordings to spacious blooming semi-tubey sound, without losing detail. The bass remains tight and clean. I highly recommend. I will say that in its stock form it is pretty good but I hesitated to use it a lot because the bass lost detail and you could hear "the buffer". After the NOSValves job now I use it even when I am playing my Jolida tube CD player. I love what it does and how invisible it is now. Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted October 24, 2011 Share Posted October 24, 2011 KC (spooky pic, by the way!) 10K still seems on the high side to me, and I can't seem to find a spec listed for your CDP, but I'm sure you're getting it from the manual, correct? In any event, if it is a correct value, then you are right in terms of what we both know about the 1:10 ratio -- thus my suggestion to "experiment" as you are intending to do. I do understand your curiosity about this, and I guess I'm just going through a kind of less-is-more sort of stage in my audio development, or something... ALL in this hobby as far as perceived sound quality is entirely subjective. Go by what you like, and not necessarily (to say the least) by how something measures, etc., etc, or what others (like me) might say about extra circuitry or anything else. You might try a buffer stage and love it. Quote Link to comment Share on other sites More sharing options...
djk Posted October 24, 2011 Share Posted October 24, 2011 As I explained earlier, the owner's manual spec of 2V RMS into a 10KΩ load is not the output impedance. Quote Link to comment Share on other sites More sharing options...
killer clown Posted October 24, 2011 Author Share Posted October 24, 2011 Thanks for the input .I am researching the concept of the buffer.I have made no final decision and may not even experiment with it.If I do try it I would like to use quality parts and a known design.If I do not like it I could probably sell it for the investment to someone.How about some designs with arguements for or against a design.Thanks.K.C. Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted October 25, 2011 Share Posted October 25, 2011 If the description of 2v into 10 k ohms, as djk mentions above, is right, he is also right. That's not the output impedance of the player. Quote Link to comment Share on other sites More sharing options...
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