It's Here! and it is Beastly

[drewh1]

Just arrived, big heavy box. Can't wait to start. I already made a cherry base for it, hope the plate fits    Still need to order the EML Tubes and V-Cap caps.  I am doing a couple of mods right from the start, having built three kits already and modified them, I feel pretty comfortable with the design mods I'll be making.

 

[drewh1]

Dang, this thing is heavy, if that is any indication of how it is going to sound, then it is going to sound great!  Just ordered caps and tubes, so hopefully everything will be here by the time the wiring is done.

 

[drewh1]

Really curious about the use of a 0 ohm resistor as opposed to a single wire for ground on pin 4 of the driver tube? Noise filter?

 

[Paul Birkeland]

It does just function as a more convenient jumper.

 

[drewh1]

Looks like I am having a similar problem to Ed's (ebag4).  I am trying to complete the HV tests but keep blowing the 1.5 fuses. No smoke or smells of any kind so I don't think I fried anything.

I double checked all the wiring and everything looks correct, had glowing tubes and proper voltages prior to this test so I'll try a larger fuse to get through the test.

Let me know if you think I should look at anything else prior to trying a larger fuse.

 

[Doc B]

Try a 1.5A or 2A slo-blo.

 

[drewh1]

Thanks Doc. Radio Shack was out of 2A's so I got 3As to test with.

Could I run with a 2A slow blow on a permanent basis? or just to test it?

 

[ebag4]

Drew, I just tried the 2 fast blow, they did just that.  Then I tried the 2amp slow blow,, it powered up and held.

2 amp held on mine until I had it all put together with the 300bs in, but had to go with the slow blow.

Best,
Ed

 

[drewh1]

Just completed all my HV checks. Used a 3A fuse.

10U - 268
14U - 554
15U - 271

53U - 75.3
65U - 76

Moving forward!

 

[drewh1]

Music!  Tomorrow I'll take some final voltage readings to see where I stand for the EML tubes.  Too late tonight, but I just had to get it done.

I assume I should take some voltage readings before installing the DC Filament regulator?

 

[ebag4]

Congrats Drew!

Best,
Ed

 

[drewh1]

Thanks Ed!

Paul J - After letting things settle in a bit and setting hum pots etc, I measured final voltages.

both filament voltages are  5.25
63u  - 72.1
33u -  72.8

c2 -  429
B2 - 428


If I measured correctly, I come up with 30.8 watts? I am guessing the voltage on pin 2 is not the way to measure plate voltage?
Looks like the filament voltage is perfect if I need an additional 5%. Will the DC Regulator take it down to 5 V, thus leaving me with low filament voltage?

I have attached some photos of my input wiring with Goldpoint and servo motor volume control.

drew.

 

[deepcmd]

Having the same issue with blowing the 1.5 fast on HV tests after putting in the 300Bs.  Thanks to you guys, had some slow-blo replacements on hand that I'll try tonight. Appreciate you blazing the trail for us (not literally of course)!

 

[deepcmd]

2 amp slow blow fuse worked.  Got 73.4V and 72.7V on 53U and 65U respectively, with no other changes made since blowing out the 1.5V fast fuse.

 

[drewh1]

Great. Ed just got a clarification on the fuse issue. Check the other threads.

So after about 10 hours I thought I would post a quick review. All this is in comparison to a modded stereomour FYI.

So, wow. I am impressed. Bass is deep and well defined. Instrument separation and clarity are excellent. Has just the extra punch and volume I need with my 92 dB speakers. Vocals are amazing, right where they should be and slighly forward. Most 3d presentation of any amp i have owned.  It improved on pretty much everything. And I really enjoyed the stereomour. The only thing I am missing a bit are the super crisp cymbals but things are not even settled in yet. Can't wait to hear it with the Eml's. Should have them later this week.  I am glad I waited for this amp. Just what I wanted.  Gonna set the stereomour up in the bedroom with a small pair of hemp speakers.

Paul j. BTW I posted voltage readings a couple of posts back. 

 

[Paul Joppa]

Since I don't have any post in this thread, I must have asked for voltages in another thread. I don't recall why I asked for that - too many posts under the bridge, plus a weekend spent throwing acres of driftwood logs back over the bulkhead.

 

[drewh1]

Ah. Makes sense.  My apologies. You were helping me set up the Eml's meshplates in the thread titled use of bias probe. I thought it would make sense to continue it here.  I want to set up correct voltage for the meshplates

 

[Paul Birkeland]

Thanks Ed!

Paul J - After letting things settle in a bit and setting hum pots etc, I measured final voltages.

both filament voltages are  5.25
63u  - 72.1
33u -  72.8

c2 -  429
B2 - 428


If I measured correctly, I come up with 30.8 watts? I am guessing the voltage on pin 2 is not the way to measure plate voltage?
Looks like the filament voltage is perfect if I need an additional 5%. Will the DC Regulator take it down to 5 V, thus leaving me with low filament voltage?

The voltage the plate sees is the plate voltage minus the DC voltage at the top of the 1K resistor.  For one side, this is 429V-72.1V, so 356.9V.  Current through that tube is 72.1mA, so plate dissipation is about 26 Watts.

Your filament voltage is within 5%, which is great.  The regulator will regulate to 5V (at a tighter tolerance than 5%).  I'm not sure what you're asking when you mention low filament voltage.  Low filament voltage for a 300B is going to be more like 4.5V.

 

[drewh1]

Paul - thanks for that explanation. I knew I was missing something.

So - EML Mesh draws 1.4 amps so, 5.25 volts on 1.2 amps (sovtek tube) would be more like 5 volts on the EML. Does the DC regulator (not yet installed) provide 5V independent of current? if so I that is perfect for the EML. Spec is 5v +/- 4%

26 amps is the maximum plate current for the EML. It would be better to have it at 24, recommended is 22.  But it all looks workable with no modification. However, if I wanted to bring it down, what would be the best option?

That leads me to a follow up question - I might be moving in with my GF  .  House voltage there is 119, mine is 125. How much does a difference in AC voltage affect the output voltage of the transformer? Might be just right if it reduces the voltage a bit.

BTW - I appreciate all the time you are taking to respond!

drew.

 

[drewh1]

I'm sorry - 28 is the maximum current. 26 is within operating range.