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SOHA II Builders Thread - Page 60

post #886 of 1686
that looks like a fine tuned Italian machine - suites your online ID - superbly done as always ..dB
post #887 of 1686
Very sweet Ferrari!
post #888 of 1686
Thanks for the kind words, Don and Shelly.
post #889 of 1686
Beautiful work, Ferrari. May I ask what kind of a circuit did you use for those analogue VU meters and where in the SOHA II's did you hook it up? I recently scavenged some vintage VU meters from an old tape deck someone was throwing away and I've been thinking of using them in a DIY project, perhaps even on my SOHA II, but I haven't figured out how it would be best to install them. Obviously I don't want them affecting the output quality.
post #890 of 1686
I'm not really feeling the VU meter vibe but the craftsmanship and design are exquisite as per usual. can you put out an absolute dog of a build just to make us believe you are actually human.....
post #891 of 1686
Quote:
Originally Posted by Arkku View Post
Beautiful work, Ferrari. May I ask what kind of a circuit did you use for those analogue VU meters and where in the SOHA II's did you hook it up? I recently scavenged some vintage VU meters from an old tape deck someone was throwing away and I've been thinking of using them in a DIY project, perhaps even on my SOHA II, but I haven't figured out how it would be best to install them. Obviously I don't want them affecting the output quality.
To drive the analogue VU meters, I used the driver circuit as depicted below. The working of this driver circuit is very simple: the amplifier around T1 and T2 amplifies the line level signal to the desired level, the signal is then passing through the rectifier diodes D1 and D2. C4 smooth out the signal a bit before the signal is feeding to the VU meter.

Before use, an adjustment needs to be made.
Connect the circuit + VU meter to a function generator which output a 1KHz signal, ~300mV.
Dial P1 to its minimum (R=0), then dial P2 until the VU meter is reaching its maximum.
Next, turn P1 up until the VU meter is at ~ 50% of its total range (12 o’clock).

Depending on the level of the input signal (SACD player, DAC…), you might have to re-adjust P1 to get a proper reading of the VU meter.
For stereo application, 2 driver circuits are needed.


post #892 of 1686
Any news on the custom faceplates? Or cn someone send me the Files ?
post #893 of 1686
I can't believe no one can even send me a face-rear plate file for the Stacker II so I can have these made at that faceplate co (can't remember their name.) I hate case work btw. Would much rather spend the bucks on machined faceplates.
post #894 of 1686
Absolutely stunning Ferrari, I wish we could clone and commission you for every build :P
post #895 of 1686
Hello Guys,

I've got a kind of strange problem here.

I've got hum - relatively quiet, both channels - not changing with the volume level.
First thought my cable was damaged ...

It disappaers when i connect one input (no matter left/right) and
"brigde" signal and ground on the other cinch connector.
Kind of fading out, turning to hiss and then disappearing.
I also made it disappear by simply changing to position of the cable.
Means twisting it or something like this.

Cable is a 3,5mm jack to 2 cinch adapter.

The hum also stays when no cable is connected.

Just ask if my explanation is not clear, I'm no native Englishspeaker and this is really kind of hard for me to explain.
post #896 of 1686
use shielded cable and run it as far as you can from the tubes. tuck it up to the edge of the chassis as you run it back to front. For the shield, ground at one end only. I ground at the entry, that is the RCA jacks. The end that goes to the board, I leave floating.
post #897 of 1686
I am using a shielded cable - the adapter cable is studio quality.
But I think you're talking about the connection inside the case?
Inside I don't use shielded cables but never had any problems with that.
(Not with my SOHA I and my M³ ... all my builds are in wooden cases.)

The strange thing is that the hum disappaers under the discribed circumstances.
post #898 of 1686
Quote:
Originally Posted by Ferrari View Post
To drive the analogue VU meters, I used the driver circuit as depicted below.
Thank you for the details, I finally had the time to experiment a bit with the VU meters I scavenged from the dumpster, and this circuit seems very suitable for them. =)
post #899 of 1686
Good to know!
post #900 of 1686
Ferrari, that's one nice looking SOHA II!!!!

I modded my SOHA II prototype to run a B+ of ~241V and 219V on the plate using 5mA per triode (10mA tail current per tube).

I can't say, right now, if there's much difference. Things do seem "thicker" with more depth. I'm sure psycho-acoustics are in full effect, but it seems nice. The voltage and plate current were influenced from the Bijou.

If anyone is interested, I used the TL783 but floated it. I wired a 50VA transformer in reverse to output 230V. I don't have one that'll fit my case, so I'm trying to find something. I'm just using jumper leads now. I initially had a 6VA transformer in, but it didn't supply the voltage I wanted, too much current, I think. I have a 12VA and 20VA on order.
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