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07-01-2009 Post mapped to 2 branches of Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 1
Post ID: 10956
Reply to: 10956
The DSET perspective examines the Herb Reichert article.
fiogf49gjkf0d

The “Enjoy His Music” published the old celebrated by many DIYers Herb Reichert’s article about his 300B amp ideas.

http://www.enjoythemusic.com/diy/0709/flesh_blood.htm

I read it before but reading it now, after a few years again, created a strange arguable attitude in me. It is not that I agree or disagree with what Mr. Reichert said. My agreement is irrelevant and in many cases is immaterial. However, this time I read the Herb Reichert’s article from DSET perspective and I recognized that many of Mr. Reichert’s points of view are irrelevant. So, let see how the DSET concept might examine the “Flesh And Blood” approach.  I very much not in position to argue technical points with Herb Reichert due to our non-comparative experience but I am in position to use a common sense to analyze the subject, that I will be using.

  Herb Reichert wrote:
Output transformers are the cornerstones of any tube amplifier design. Since 1980, I have tried outputs from UTC, ACRO, Peerless, Dynaco, Fisher, Partridge, Western Electric, Chicago, Hammond, Magnequest, RCA, Audio Note, and God only knows...? I prefer the Tango to any other. I distributed Tango in the U.S. until 1993. Maybe that's why I began this design with the Tango XE-60-5S single-ended output. I do not care how "romantic" you want to be, you must have speed and bandwidth. An amplifier that is slew limited or unstable outside of its passband will never have good tone character. I believe the ultrasonic and infrasonic behavior of a SE amp must be carefully examined. Excessive phase shift or ringing in these regions will surely sabotage the amplifier's potential for greatness. If the output transformer rotates phase more than 40 degrees below 100 Hz, the amp will sound slow and the bass will seem to lag behind, lacking "tunefulness". Bass transients will sound dull. Likewise, if there is ringing in the ultrasonic region, the amp will sound hard and 'hollow'.

Yes, Mr. Reichert is very much correct – the Output transformer is a hart of SET amplifier but then he begin to talk about the output transformers passband and phase rotates at the peripheral frequencies. Let pretend that Tango XE-60-5S does a very good job but phase rotation is the subject of parameter where the proximity to the transformer’s cut off is the most critical. Any DSET configurations where you have a transformer dedicated to LF and a transformer dedicated to HF extends passband enormously, extends power handling enormously and as a result create a condition to much lower phase shift atop and at bottom. Did I say that in DSET works it shell not be  “very good” and very expensive Tango XE-60-5S that Mr. Reichert use to sell but it might be two transformers with price and sophistication of a power transformer for Mr. Reichert’s amplifier?

  Herb Reichert wrote:
  The proper selection of core material, core size, aspect ratio, and winding technique is far more critical in SE designs. Poor choices lead to soft, lazy, unrefined sounding amplifiers. The Tango line is unique in that it is the product of two decades of continual development. World-wide, there are thousands of SE amps with Tango outputs. The Tango XE-60-5S measured 18-80 kHz, -2dB in this amp. This is at 7 watts! Remember, I do not sell these transformers anymore. I just still love them.

First of all I do not really believe that Tango XE-60-5S measured 18-80 kHz at -2dB at full 7 watts.  If it was SO GOOD that it did then in DSET configuration it would be at fraction price with 8Hz-200 kHz at 7 watts. As you understand with this bandwidth the critical phase shift in 20-20,000 region would be much less.

  Herb Reichert wrote:
I chose the WE 300B tube after living with amps built around the 6B4G, 2A3, 50, 45, 801A, and the 10Y. 10Ys push/pull are still my personal favorite, but even the VOTs like more than 3 watts. Of the available triodes, the 300B plays the most records with the greatest ease and the most refinement. It is voluptuous and elegant.

Are we talking about A1 operation?  If Herb Reichert drove his VOT, his LS3/5A and his AR-M1 with 2A3, 45, 801A and intended to get full-range from them, then my question would be:  how far into A2 those amps dived? In a regular size rooms those amps would not have power to drive bass drivers in more or less mode. Then Herb admits that push/pull was still his personal favorite. I am sorry but if a person prefers a push/pull over SET and if the person is not fool or deaf then there is the ONLY one explanation – the person’s SET did not have enough power to drive the given speakers. With DSET it is not the case. The biggest problem with luck of power is that when a full-range amp approachs clipping in bass then it generates LOT of UFH harmonics that modulateivly destroy the MF and HF of the auditable upper bandwidth. With DSET there are no direct intermediations between the LF and HD DSETs and what the bass clips it has no impact to HF DSET.

  Herb Reichert wrote:
Operating points are next on the design agenda. My best friend and tube maven, J.C. Morrison, has already written the book on this subject: run your triodes hot!

Sure, run them hot, run them even more hotter if you have even less power for the given speakers. They call to run the tube hot to drive the plate impedance lover and to increase loading, which would give more power from the tube. I in opposition to it and I would call do not run the tube hotter but to peruse for more sensitive loudspeakers. If a tube runs at 70% of own full power then way shall it need to be run hotter?

  Herb Reichert wrote:
With pentodes, I like low plate voltages and high current. With triodes I like high plate voltages AND high current. I run the WE 300B at 425VDC on the plate and 80mA standing current. I want deep class A1.

If you want deep class A1 then use higher sensitively speakers and run lower voltage on grids. You have 3 stages in your amps - a lot of gain, with the 50, 45, 801A, and the 10Y you will not have enough power. The Altec VOT are ported and when those 15” driver hit in the ports after-resonance current suck out then you need all power from amp to handle it. The Altec 15GE has 28Hz of Fs and approximately 38Hz in the Altec. The Altec 15ABC had around 60Hz …. So, to say that your SET has a few watts at 20Hz is hardly important in real world.  Now, Herb wants the “deep class A1” and become of it he drives his tube “very hot”.  Higher voltage on plate = higher voltage across primary of output transformer. The higher voltage across primary = stronger isolations of turns on the primary. The stronger isolations of turns = higher capacitance. The higher capacitance = more phase shift at high frequency. So, Mr. Reichert wants more power but the more power is applicable only for LF, why the HF shall suffer if HF does not need more power? The DSET is an ultimate solution for this conflict as the power equipment for LF and HF are not relevant to each other.

  Herb Reichert wrote:
The power supply is everything in these little amps and it also seems to be the area where designers agree the least. All the SE 300B amps I have heard sound very different from each other. Some sound more mechanical than the worst solid state designs. The reason, I expect, is wildly different ideas on power supply design. First rule of triode amp design: Solid state rectifiers = mechanical sound. You don't think so? Then you haven't really compared. I promise you, IF there is only ONE thing I have learned in ten years of amp design, it is this first rule. A lot of time went into selecting the rectifier tube for this design. Normally, I use the WE 274A/B, but this amp sounded best with the RCA-5R4GY.

First of all I disagree. SS fast rectifiers with input choke had not the problem. If to follow the Herb’s logic then I would state that tube rectifiers = no bass. Again, go DSET.  If we feel that solid state rectifiers = mechanical sound but better bass then use if for LF of DSET.

  Herb Reichert wrote:
The pi-filter is the heart of this amplifier. If this amp sounds better than others, it is probably due to the choke/cap selection on the pi-filter. I don't like to waste a lot of energy charging and discharging caps. I want a narrow torque curve - high rev supply. Low impedance and minimum storage gives fast recovery and fine texture to the sound. Remember, most amps under 2000 watts are running at or near overload. Let's make them sound unstressed at overload. Then the music will sound unmechanical. The power transformer should be rated at least 500mA at 800VCT. An even higher current rating is better (I use 750mA) because I want a small value bleeder resistor at the end of the filter. I like to bleed at least 25%% of the total standing current. This stabilizes and regulates the supply. With the small Black Gate caps, the heavy bleed appears to enhance the clipping characteristic.

This is all bogus comment in my view. Mr. Reichert uses small 47mF caps to short his AC that come from plates back to PS. With this capacitance the LF AC gets shorted passing the chokes, and even rectifiers. Of cause their quality because important. Do you want to shape the amp’s sound by the type of the turns you have in PS’s chokes and the quality of your PS weirs?   I think this is how audio “urban legends” about PS are stated…. I will leave all the rest Reichert’s PS comment alone…

  Herb Reichert wrote:
I am not going to get into the parts philosophy thing except to tell you I have tried everything I could lay my hands on. My ideas change daily so here are today's recommendations. No Teflon. No silver plated wire. No MIT multi-caps. No metal film or metal oxide resistors. No polypropylene caps. No Vitamin Qs. No Solen. No REL caps. No Holcos. No metal oxides. No Vishays. No SCR. No MKP-1845s. No solid state diodes. No solid state current sources. No silicon anything. If you use this stuff, you know who's amp design it is NOT. Please use Allen-Bradley resistors in the plate circuits. Paralleled resistors, in plate circuits, are quieter and sweeter sounding. Use Audio Note Tantalum resistors in the cathode and grid circuits. On the cathodes of the 300Bs use Caddock 50 watt MP 850s. You can use Caddock MG or MX in the plate circuits if you are a noise freak, but I think the A/Bs sound more relaxed and showcase the wood and brass tones on orchestral music. I have only three recommendations for coupling capacitors and they are all Audio Note. Due to my affiliation with Audio Note you probably won't take my coupling cap recommendation too seriously, but that's OK. You lose! If you want even a chance of catching my Ongaku sonically you must use Audio Note silver foil paper in oil coupling capacitors. If you can't afford these use AN copper foil paper and oil capacitors. There simply are no other choices.

Probably I need to state that I have tried the Audio Note silver foil paper in oil coupling capacitors and I really hate them but it is not the point. The point is that if Mr. Reichert has his preferences then the questing I would like to ask: does he has his preference in context of a full-range or in context of DSET? If Mr. Reichert such an experienced person then could you imagine how much further he can take his voicing skills if he uses them separately for LF and HF amplifiers of DSET configuration?

  Herb Reichert wrote:
Wire is a separate issue. Wire is a system thing. After twelve years of building amps, I only know two things for sure:

1) Use tube rectifiers

2) You can never have too much silver in the signal path.

Go without food or clothes, but buy lots of records and wire your hi-fi in silver. Audio Note or Kimber silver wire are my first choices for internal wiring of this amp. If you can't afford this stuff, just use Carol PVC hook up wire. Nothing is worse than silver-plated copper. Stay away from all Teflon coated wire if you are looking for relaxed natural sound. Believe me the Carol PVC stuff is good for everything in your system from the tonearm to the speaker. If you can't afford silver, and you trust me, try it.

Although, I disagree with silver paranoia at all I would like to strike it with DSET concept. What more silver but feel that OPT silver transformer too expensive (and they are!). Go DSET! For LF you need no silver (even the silver-crazy Mr. Reichert would admit it). The transformer for HF part of DSET will be much smalls and will have much less turns (need to inductance) and there it will be MUCH chipper. For the save money the Reichert’s people can dip the silver HF transformer into liquid platinum …  

  Herb Reichert wrote:
In fact, if you want to build this amp on a budget, try this... you can still say it is my design. Use the Tango XE-20S or the Audio Note outputs. Use the Carol PVC wire, the AN Paper and Oil Caps (Regular type), Allen-Bradley resistors, and Sprague or Mallory power supply and bypass caps. You will lose some of the refinement but none of the naturalness. If you make substitutions with parts try to avoid plastic, especially hard plastic. Think voluptuous and colorful. Oh yeah, even if you are on a budget, try to use a copper chassis, 2% to 4% silver solder, and high quality ceramic tube sockets.

In fact, if you want to build this amp on a budget… then go DSET. It delivers higher performance foe the less cost.

  Herb Reichert wrote:
This circuit and these parts choices were developed inside the world of my hi-fi to my taste! If you want an exceptional music reproduction system in your home you must first develop your internal reference for natural sound. Then you must outline your aesthetic and make a series of design decisions that reflect that aesthetic. But remember, you won't be happy if you acquire your aesthetic from reviews and audio pundits. You must discover your own. Trial and error is tedious and it takes a long time to become a wizard, but I am sure you will look good in the wizard's cap.

Indeed, I might talk a lot about it but I would like to in this thread to operate by the facts, at least the fact of common sense. My common sense advises that DSET overrides many of Herb Reichert recommendations. Agree you or not but I think the point worth to be presented.

Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-02-2009 Post does not mapped to Knowledge Tree
floobydust


currently roaming the US
Posts 62
Joined on 01-19-2009

Post #: 2
Post ID: 10962
Reply to: 10956
Opinions are like.... well, you know... everyone has one.
fiogf49gjkf0d
 I looked at the schematic for Herb's 300B SET many years ago. It's been copied and slightly modified by many.... personally, I would not use it for a 300B amp... then again I probably wouldn't use it for a 2A3 or 45 either (I think my input/driver design for the 45/2A3 is much better). Despite the 6SN7 being an excellent twin triode, I've concluded that you can't drive the 300B with an RC-coupled design based on this tube, at least not very well. The 300B is a real bitch to drive due to the high input capacitance. The testing I've done shows far too much dynamic compression as you drive the grid closer to zero and a sharp increase in distortion. I've abandoned RC-coupled for the time being (for the 300B) and will work on a transformer coupled design when I get more free time. I prefer to keep a lower cathode current, step up the plate voltage and run a higher impedance load on the tube (same for the 45 and 2A3). I also prefer a 5K load on the 300B however, with higher voltages of course.

 You can bias a DHT for lower distortion at higher power levels and promote longer tube life if you don't push the cathode so hard and risk overheating the tube. Overheat it once and it's likely to be damaged.... especially if you cherried the plate in the process. Excess heat is still an enemy of the vacuum tube, last I checked. I'll run the plate dissipation up but I prefer to keep the cathode current below the maximum rating.

 His ranting about No, this, No that, etc. on parts selection is just personal opinion... as he clearly states his design satisfies his personal taste in sound. I think most people develop a predilection for certain parts... resistors, capacitors, connectors, wires, sockets, etc. Again, simply personal choice based on what you like and what you can afford. I'm the same way for my personal gear. I still hate pretty much all connectors however... even some of the most expensive are mediocre for getting a pure connection. I also prefer NOS tube sockets and have a nice stash of them... EBY, Cinch, Amphenol and some others. All are silver-plated pins but most are not ceramic. When you're dealing with frequencies below 50KHz I doubt you'll find any real sonic difference... especially with a rectifier tube or a 4-pin UX4 for the 45, 2A3 and 300B. The newer stock of Chinese-made stuff doesn't cut it in my book. You can only get so close using metric equipment to make SAE spec parts and quality control problems make it worse.

 I think his comment about prefering 10Y in push-pull can be interpreted two ways... one, that he prefers push-pull operation over SE, or two, that he prefers the 10Y triode in push-pull over the 10Y in SE mode. I think if he really prefered P-P overy SE than he wouldn't have spent much time doing SE designs. Again, just my $0.02.

 As for the Wizard's cap... I don't want one... I'm not making magic or doing anything paranormal. When I design a circuit, I void everything in my mind and start clean sheet... plate curve charts come first... selecting component parts comes last. I do believe that the physical layout and construction can make or break any design however... taking a schematic and engineering it into a product is in most cases more difficult than doing the design itself... the reality of it all settles in and can bite pretty hard. To this day I still breadboard everything first. The real goal is to make an amplifier that has no sonic signature of it's own.

 Still, you made some very good (and valid) points. I've not ventured into DSET territory yet.... but I have managed some very well optimized SE designs engineered to final products that perform very well... both measured and audible. Common sense should be your guide.

 Regards, KM


... just because you're paranoid, it doesn't mean they're not after you ...
07-02-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 3
Post ID: 10964
Reply to: 10962
I would like to advice the DSET concept.
fiogf49gjkf0d
My objectives when I wrote my initial post were not to knock the Herb Reichert’s design ideas but to demonstrate that DSET topology make most of Reichert’s views not applicable or even irrelevant. So, my post was not against Herb but rather to advance the DSET concept.

This is kind of absurd: DSET topology has so many advantages but it is not widely used. The point that I am trying to make is that if audio people spent as much time and efforts purifying  and improving DSET concept as they spend to  think about the type of capacitors, amount of silver in cables or finding the sources to wound output transformers then they would get, in my view, more interesting results.

Rgs, the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-03-2009 Post does not mapped to Knowledge Tree
floobydust


currently roaming the US
Posts 62
Joined on 01-19-2009

Post #: 4
Post ID: 10966
Reply to: 10964
Parts is parts?
fiogf49gjkf0d
 Agreed, not really knocking it, but I've used a similar/same input/driver on the 300B and the results were not satisfactory in my view. I think the view of using premium and exotic parts got started years ago... where people wrote that due to the simplicity and low parts count in a typical SE amp with no feedback, you could spend the $$ you saved on overall parts count towards premium components. The rest gets down to carrying the concept to extremes in some cases and diminishing returns.

 Regards, KM




... just because you're paranoid, it doesn't mean they're not after you ...
07-03-2009 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 240
Joined on 03-01-2008

Post #: 5
Post ID: 10968
Reply to: 10964
Evolution
fiogf49gjkf0d
It is a pity you can't be persuaded to get an OEM like http://www.meixingaudio.com/ to make the Melquiades commercially for you. Perhaps it might be possible when Jessie starts making the Macondo...
03-06-2011 Post does not mapped to Knowledge Tree
oxric
Posts 184
Joined on 02-12-2010

Post #: 6
Post ID: 15708
Reply to: 10962
Are you still in Reutlingen, Germany?
fiogf49gjkf0d
 floobydust wrote:
 As for the Wizard's cap... I don't want one... I'm not making magic or doing anything paranormal. When I design a circuit, I void everything in my mind and start clean sheet... plate curve charts come first... selecting component parts comes last. I do believe that the physical layout and construction can make or break any design however... taking a schematic and engineering it into a product is in most cases more difficult than doing the design itself... the reality of it all settles in and can bite pretty hard. To this day I still breadboard everything first. The real goal is to make an amplifier that has no sonic signature of it's own.

 Regards, KM


Hi KM: I am sorry to ressurect this defunct thread but it is in the hope I may be able to get in touch with you. Reutlingen is not far from where I am moving on the border with Germany, and in fact a good friend of mine is moving to Karlsruhe in the next few months, very close to you. I would be interested in looking at your designs if you have a website, or a shop...Please contact me by email at:

rakeshpoorun(at)gmail.com

 I hope I have not violated any number of Goodsoundclub's rules of etiquette regarding contacting other members. If I have done, I sincerely apologise and please feel free to delete this post. RegardsRakesh






Page 1 of 1 (6 items) Select Pages: 
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  A DSET is better then an expensive SET..  DIY Stradivarius...  Audio For Dummies ™  Forum     41  239831  09-21-2007
  »  New  Single-stage Melquiades vs. DHT amps..  A hallucination?...  Melquiades Amplifier  Forum     397  2499096  11-22-2008
  »  New  6 Channel Version of Super Melquiades..  The first Milq screw up....  Melquiades Amplifier  Forum     131  844564  08-08-2007
  »  New  5 Channel Version of Melquiades..  Very easy....  Melquiades Amplifier  Forum     21  161990  07-23-2006
  »  New  Dual channel SET..  Space exploration...  Audio Discussions  Forum     8  53908  04-17-2008
  »  New  If you’re multiamping then use passive-line lever cross..  Crossover and DSET?...  Audio For Dummies ™  Forum     3  35617  01-21-2009
  »  New  Incorporating active crossovers into DSET..  Thanks...  Melquiades Amplifier  Forum     2  29105  07-22-2008
  »  New  Think ahead how to measure the DSETs gain...  The calibration mode is for DSETs not for SET....  Audio For Dummies ™  Forum     2  18177  09-17-2009
  »  New  Thomas Mayer’s Triamp..  It is much more then juts "properly calculated and...  Melquiades Amplifier  Forum     2  24658  03-03-2010
  »  New  Multi-amping crossovering...  No input capacitor......  Audio Discussions  Forum     6  40460  09-24-2010
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