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Posted
On 2/17/2016 at 3:38 PM, JoaMat said:

Life is short. Would T2 accept EML 20B-V4 tall base?

IMG_1442.thumb.JPG.3263ce77ca71846b4cc99

Yes, she does! For how long?

is the el60 a viable replacement?  how do you wire the adapters?

Posted

EL60 is said to have the same characteristics as EL34 but it has 9 pin socket. The adapters are bought via eBay and quality seems OK. IMO EL60s are very good sounding tubes.

Posted
49 minutes ago, JoaMat said:

Sold rk50. Got money enough for tubes, bottle of single malt and flower to wife.

it's spelled "flour" - probably a good idea to keep the wife occupied

  • Like 3
  • 3 weeks later...
Posted (edited)

Have listen to the DHT carbon style for three weeks now. It’s bloody good – think I like it more than the T2. Below is a draft of how a smd version of DHT might look.

56dddc0d20f74_DHT-3DVisualization.thumb.56dddc12b69fc_DHT-3DVisualization1.thumb

 

Edited by JoaMat
  • Like 5
  • 1 month later...
Posted

Left channel is a GG. Followed Kevin’s schematic. Intention is to use Emission Labs DHT, didn’t dare to test it with DHT so it’s populated with some modern less expensive EL34. Right channel is an old Blue Hawaii. The combination of BH and GG works terrific.

IMG_1476.jpgIMG_1479.jpg

  • Like 6
Posted (edited)

I haven't got it to work right, can't be much, a part choice of mine? or something really simple..

I occasionally do real stupid stuff and don't see it.

so far 3 boards and same result, low bandwidth (under 1khz)

Will revisit after finishing some other projects... (June?)

Had two resistors wrong......... Now it works

Edited by congo5
Posted (edited)

As I posted earlier I rebuilt a Blue Hawaii to GG. And now this new one. I can only say that Kevin’s GG works very well.

I’ve the opto servo on the board, didn’t flip (or, did flipped it, depends on ones perspective) the opto coupler when mowing it to the other side of board. After correcting the connections to opto coupler the servo still doesn’t work. Have to find the reason for failure. The opto servo should work, shouldn’t it?

Edited by JoaMat
Posted (edited)

While speaking servos. The small board between tubes on Blue Hawaii (right channel) is a servo a la T2 (picture a few posts up). Did built it after Kerry suggested that one maybe should do it simple when we tried different servos some year ago. That servo works great.

 

Edited by JoaMat
Posted

Regarding the opto servo. Eventually I spotted the fault. Transistor mounted the wrong way. Now servo working and it works very nice.

Really like the opto coupler. Many thanks Kevin.

  • 2 weeks later...
Posted

For the 4 tubes, is there really benefit to go unregulated PS or even regulated PS? Because I wanted to do two-box design and buckle the heater wire with others to use a single connector. I suspect AC 60hz noise will affect others. Heater for el34 needs 6.3V/1.5A each. So I will aim for about 10A for the PS. Also, the heaters are sitting at -450V, so the PS should be floated?

I wanted to go tiny and simple. For single regulator, I could only find MIC29712WT, which is only 7.5A max. 

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