Tube Audio Design TAD-60 Amp

You can read the history on Tube Audio Design in my TAD-150 Preamp post. This is the amp that pairs with it. The cool thing about this amp is that it can be used as a standalone integrated amp if you need it to. With 1 input, if you move the volume button all the way to max, it opens a direct path for the preamp when used. It has 4 & 8 ohm speaker connections. This amp is built like a tank. It weights just about 50lbs!

The amp is very versatile. It comes standard with EL34 power tubes, but can use a variety of others as well, including KT-66, KT-77, KT-88, and more. The best tubes that have made the amp simply amazing are some Genelex Gold Lion KT-88′s. Push-Pull Class-A Design, UL or Triode Mode, Variable Feedback, and has external easy biasing. I’m using a pair of Amperex 12AU7′s, and a single NOS Sylvania 5751 Black Plate Triple Mica.

If you have any questions about this awesome amp, please feel free to leave a comment or contact me.

Push-Pull Tube Biasing (based on 2000mV reading):
EL34′s: 350-370
KT66: 375-400
6550, KT88, KT90: 600-620

Class A biasing:
EL34: V1+V3 @ 200mv; V2+V4 @ 500
6CA7: V1+V3 @ 300mv; V2+V4 @ 500
KT66: V1+V3 @ 250mv; V2+V4 @ 450

tad-60-amp-1
tad-60-amp-2

Here is the complete BIAS instructions from Paul Gryzbek:

TAD-60 BIAS INSTRUCTIONS Very important : 
Tube bias must be set immediately when tubes are first installed. Excessively high tube bias will burn output tubes in a matter of minutes. Output tube glass gets very hot and will burn your skin – be careful. T AD-60 bias adjustments are very precise 25-turn pots. Turning right raises the bias. Please read instructions below. 

WITH NEW TUBES INSTALLED:
1. Start with the amplifier off and cold, all tubes properly installed. Turn all 4 bias adjustment screws to the left 3-5 complete turns. Speakers do not have to be connected to set the idle current bias. Make sure music is not playing during the adjustment. 

2. Set the supplied digital meter to the marked 2000m V range. Clamp the meter black probe into any speaker terminal post – or simply place the black probe into one of the brass top cover mounts. Place the red meter probe into one of the top chassis gold RCA bias jacks, notice screw adjustments next to each test jack (see picture).
3. Now power up the amplifier NO music playing. Watch the meter – if the meter reading quickly rises above 600 IMMEDIATELY switch the amplifier power off – the bias adjustments are not set to a low initial bias adjustment starting point and need to be turned left a few more turns. Once the amplifier is switched on you should see a relatively low reading:(1 to 300) in 15 seconds. Adjust each corresponding bias screw for this meter reading: EL-34 tubes set to 350, 6550 or KT -88 tubes set to 550. Set the remaining 3 bias adjustments in the same manner by moving the probe to the corresponding bias gold jack and turning the adjustment screw. 
4. Let the amp idle for 10 minutes (or longer) at this setting. Watch out, tube glass gets very hot (up to 300 deg. F) 
5. After 10-minutes (or longer) of idle time, final adjust all 4 settings: EL-34 set to 350-370. 6550, KT -88 or KT -90 tubes set to 600-620. + or – 20 is accurate enough. Final test and adjust all 4 test points two or more times till all look identical. The bias is now properly set and will not need attention for 6-months. 
the correct 4 or 8-0hm + post. Speaker minus – wire goes to the amp 0 ground post. Connect the amp input to your preamp output. The adjustment can be performed with or without speakers, or input connections – just so no music is playing during the adjustments.
Check the bias every 6 months. 

 

55 thoughts on “Tube Audio Design TAD-60 Amp

  1. Hi Paul

    I don’t know of anyone right now selling one. Best bet is to keep an eye on the Audiogon listings. Every once in a while one will pop up but they go fast, so if you’re serious snag it.

  2. Hey Brian:

    I just inherited a largely-intact TAD-60 from a friend of mine whom is recently deceased. Like myself, he was an electrical engineer, and was in the process of gutting this TAD-60 to use the chassis, power supply and output transformers as a basis for one of his own designs. Controls and other items on the top chassis were removed, along with the addition of more tube sockets (!) and such. Mods underneath were also pretty extensive, but I won’t get into that part here.

    My plan is to first return the TAD back to it’s original electrical configuration. From there I will try a variety of modifications for push-pull tube amps that I have developed over the years.

    I’m wondering if you could please help me identify what controls, etc are missing on the top side, and indicate what the functions are of some switches? I can take a photo of the top chassis and email it to you, with a few specific questions. I have a schematic for a BEZ T8C-60 amplifier, which as I understand, is the original of the TAD-60, which is a mere rebranding for the now defunct TAD operation in the USA.

    Thanks,
    Dennis
    San Diego, CA

    • Hi Dennis,

      Feel free to email a pic and I can see if i can help you. Well the TAD-60 was a little more than a rebranding. Paul, the owner of Tube Audio Design used the BEZ and a base and customized it from there. It’s too bad he passed away so early. Hold on to that TAD, it will soon be a more rare item.

      Brian
      brian(at)brianmedia(dot)net

  3. Hey Brian,

    This is a great website. I happened to have saved some of the late Paul’s website. Please let me know if I could email it to you so you can arrange it in organize manner on your website. The page that I saved consist of :

    - 2007 LED TAD-60 biasing
    - TAD-60 TIPS AND COMMON ANSWERS
    - Symptom: Audible Speaker Hum
    - also a manual that Paul send with the TAD-60 (not from the late Paul’s website)

    I currently own a TAD-60 and TAD 803SD speakers and looking for TAD-150 preamp to complete the set.

    Regards,
    Andreas

  4. Andreas: Same goes for me. I’d really like to see what info you have from Paul’s old website. Hopefully Brian can reproduce that info here for all to see…

  5. Hey

    I just picked up a pair of TAD 1000 monoblocks. Any documentation anyone may have is much appreciated.

    Thanks

    Simon

  6. I believe this is a TAD-60 specification

    TAD-60 measures 50W/Ch RMS clean, 60w RMS stretched (5% soft clip)
    Proven excellent to drive any speaker you like, eficient horns to power hungry electrostatics
    Exclusive Class-A, Single Ended Bias Mode
    Frequency response: Flat 15Hz-30kHz, -3dB @ 100kHz
    Soft start circuit promotes long life
    Large: 16″W, 14″D, 7.25″H
    Heavy: 45 pounds
    Stainless steel chassis (only the best non-magnetic grade)
    Full size (17″) 5mm wide black faceplate, soft blue light
    Huge clear MIT-style gold speaker binding posts, 4 & 8 Ohm taps
    Triode Mode/UL mode Switches
    Heavy gold volume knob for integrated use, or preamp gain matching
    Heavy gold Variable Feedback control for untouchable sound quality
    Spring loaded tube shields on small tubes for shipping – remove these!
    Adjustable Input sensitivity: Full Power with only 1-Volt in or more
    Excellent huge transformers with vibration damping mountings
    Normal US audio tube types
    Supplied Tubes:(4) Select Matched China Fat Bottle EL-34B, (2) Select Matched JJ brand Tall ECC99 12AU7′s, (1) Select JJ brand ECC83S 12AX7
    All tubes are select hand full load tested and matched
    Accepts EL-34, 6CA7, KT-66, KT-77, KT-88, 6550 or KT-90 output tubes
    Huge dual rail power supply
    Overbuilt to last. Easy to service. 100% hand point to point wired. Loaded with precision wire wound resistors and a select group of coupling capacitors for optimal sound. 1960′s quality hand built today! All are completed in my private Chicago area lab for outstanding quality.

  7. Hey Brian and everyone,

    I have a question. I now have two of Paul’s TAD-60′s. I want to biamp my Vandy 2ce Sig speakers with each TAD 60. Can I do this. (N.B. I’m about as new to good audio as it gets, so be gentle, please!)

    Any help would be greatly appreciated.

  8. Andreas,

    Wonder if I could lean on you for the info you supplied Brian. I now have, thanks to Brian’s fine website, Paul’s preamp, one TAD-60 (another one from another site), and Paul’s subwoofer. After initial hookup of the TAD-60, I’m so nutty about the sound, that I’m trying to put together a Gryzbek collection!)

    Best,

    Wes
    wesley_d_baker@mac.com

    • No you would only be able to “bi-amp” if your speakers are designed as such. The amp cannot be used as a mono block. At least to my knowledge. I have one and it seems as powerful as my class d audio SDS 470c driving soundfield audio monitor 1′s.

      • So one RCA interconnect (from source/preamp) to one TAD-60 and two sets of speaker wires from one TAD to my ‘bi-ampable’ Vandersteen 2ce sigs? And one RCA interconnect to the other TAD and onto the other Vandy?

        (Sorry, I’m obviously a newbie to this!)

        Thanks for your time, Chris.

        Wes

        wesley_d_baker@mac.com

        • You need a pream with two sets of preouts. Then you can use one amp for the lows and one for the highs. Also known a horizontal bi-amping. Do not run the amps with only one channel connected as both channels need to see a load represented. As far as using one amp for each speaker I am not sure how you would accomplish that. Perhaps others will chime in and offer advice.

          I do seem to remember reading Richard Vandersteen strongly suggests bi-wiring vs Bi-amping. To do that all you would need is one amp for both speakers and a set of bi-wire cables.

          I will also add that when I had a very had to drive pair of speakers I bi-amped them with a 300 watt class d amp on the woofers and my tad 60 on the highs. This seemed to work out pretty well for me at least.

          One more thing, there is a member on another site who was selling two tad 60′s and stated in his listing he was using them in a bi-amp configuration, did you happen to get these recently?

      • No the 60 still isn’t listed. I’ve been in super procrastinator mode while in the middle of other stuff. It is sitting here partially packed. I really do need to get this puppy listed. Maybe (?) over the long weekend.

        • Thanks for replying, Dale. My friend adores my TAD-60 and told me if one ever comes up for sale to be sure and let him know….so if you’d please contact me via email so we can discuss your unit perhaps I can save you the hassle of having to list it. You can get me at spctomlin@sbcglobal.net

          Thanks,
          Michael

  9. anyone? what would be the bias for the tad-60 using genelex kt88 tubes,,,the tad -60 i have is the light led bias type,,,the newer type,,,i was told by paul it was the third light lit ,,,but i’m not sure,,

    if anybody knows,,i would appreciate it…thanks

    • I do not know about how the LED indicator bias was calibrated, but I can tell you that a pair of KT88s want approx. -50 volts on the grids when the plate is at +460 V. This would be for standard class AB1, tetrode operation. The TAD will adjust bias all the way down to -60 volts (approx) – at least according to the schematic.

      Using a voltmeter on the grids, you can set the bias pots so that bias voltage is at approx -50V and see which LEDs are lit. If a slight change of the pot up/down makes the middle LED come on, then your assumption is correct.

    • Well look what I just found in my notes on the TAD amplifier!!!

      LED BIAS:

      Adjust each corresponding bias screw for the following LED readings:
      6L6GC, EL-34 or 6CA7 tubes set to light the second (above V2) Green LED.
      6550 or KT-88, KT-90 tubes set to light the third (above V3) Green LED.

      Set the remaining 3 bias adjustments in the same manner, selecting only one test switch at a
      time. Adjust for a full bright Green LED – about 1/4 turn right from where it begins to light.
      Final adjust all 4 after the amp has been on for over 20 minutes -remember to stop the
      music while measuring and adjusting. Turn all 4 switches off(towards the front) when
      finished- You can easily verify tube bias and tube condition at any time (music not playing)
      by individually flicking each test switch to verify the correct LED is lit.

      *NEW SINGLE ENDED CLASS A BIAS: This amplifier will operate class A for the first
      10 watts and class AB1 to full rated power if biased this way:

      For 6L6GC, EL34, 6CA7, 6550/KT-88, KT-90: V1, V3 set to light the second LED (above
      V2). V2, V4 set to light the third LED (above V3).

      Notice improved smoothness in the midrange and richer bass compared to regular bias mode. Single ended, the hot biased tube is doing most of the amplification 360 degrees up to 10 watts while the cold biased tube is an out of phase” damping brake, offering little in phase amplification under 10 watts. Have it all, single ended class A and full A/B power when played extremely loud.
      Verify and check the bias every 6 months,

      • Thanks dennis…paul had all that in the site..but after he passed, they took it down..

        I appreciate taking the time out to help me..god bless..

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