A twisted tale about a logarithmic relay attenuator

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#441
I just realized I forgot to mention, I'm using one controller to two relay boards, and both boards behave identically. This points to the controller then, correct?

-edit- do you have any controller kits left? If so, I'll probably just purchase one of those. I'm suspecting the chip at this point (though I haven't done much testing) as I soldered the chip directly to the board (no socket), so perhaps I damaged it somehow.
 
#443
Alright, I've had a chance to look more closely at the problem. I ran into some steps listed earlier in the thread for checking one poster's moaterboating problem, and everything checks out fine. I'll rebuild the cable today to see if it has any effect. I'm not too sure how to further check the controller board. The power supply section of the board is working correctly, so I guess I'll reflow the solder on the rest of the components a bit later, as well.

Any other ideas on what I might be able to check? I think I mentioned earlier that I soldered the PIC directly to the board, so I'm worried that it could be possibly heat damaged.
 
#445
Dear everyone,

I have assembled most of my amp now consisting of RevC's Darwin and a JT. This is an SE amp. Everything works ok except the JT. When I turn the pot I get no clicking relays at all 🙁 so I am trying to find out whats wrong...

Tested:
  • 5 V from power regulator seems OK measured at the taps on the PC board. Darwin is fed from JT and seems to work well.
  • Ribbon cable test ok on all pins
  • PIC legs connects properly to the socket and PC board
  • Diodes on the relay board are properly oriented
  • Tried to measure the pot and got a little confused. Can one measure resistance directly between the wiper and + (or gnd)? I have ~110 ohm as max here, is this just a bogus number? I have only measured it in place and not desoldered it.
  • Inspection of joints seems quite ok, I have not reflowed them yet.
As quite a newbie in electronics I do not really know how I should go on here. I suppose that with enthusiastic poking around without really understanding how the circuit works could fry things.

Could the transistors have been killed in the soldering process? Can one test components on the boards without desoldering them?

Bad PIC? That was the absolutely last component I added into the socket before testing the tree and I don't think I have zapped it with any static.

I think I really need some good advices to continue from here. Hopefully I'll get wiser 🙂

// Jonas
 
#446
Tintin said:
so I am trying to find out whats wrong...
Click to expand...


are you sure the relays are installed properly? It's a bit confusing (IMHO) as the text on the silk is the opposite direction as the text on the relays (I know, I know there is a "dot" to indicate this, but there is also a dimple in the relay on the other side as well)
 
#448
luvdunhill said:
are you sure the relays are installed properly? It's a bit confusing (IMHO) as the text on the silk is the opposite direction as the text on the relays (I know, I know there is a "dot" to indicate this, but there is also a dimple in the relay on the other side as well)
Click to expand...

Egads! I clearly fell into that trap. Embarrasing 🙂 Yes all the relays are oriented in the wrong direction. Now I will need a good tip on how to desolder. I am decently handy in soldering but suck at desoldering these multi-leg components. I have wicks and a sucker so I guess I should start practicing on some scrap boards.

fierce_freak said:
Does the resistance you measure on the pot change when you turn it?
Click to expand...

Yes it does change to 0 but I was a bit confused since I thought the pot was 2k max but I have a hunch that I should read up on the difference between a rheostat and a potentiometer...

Wow! quickest solution I have ever had I think 🙂 but soldering will be for tomorrow night, now I need some sleep. Thanks a lot!
 
#449
Brian and Russ:

I wanted to take a chance to request a few features from the upcoming uber-controller 🙂 I'm sure a lot of people are waiting for its release.

First, a unity-gain switch. I used this on my BAT preamp quite a bit and is very useful for multi-preamp systems

Second, the ability to switch between multiple preamp outs, and thus control multiple amps / headphone amps. This way I can eliminate the necessity for having multiple volume controls in all my headphone amplifiers and push this functiona back in the chain... perhaps some strange bi-amping creation could be dreamed up as well, who knows.

Third, the ability have a buffered tape loop for chaining/sharing sources (either native, or via an add-on board like the JISBOS).

Thanks again!!
 
#450
First, a unity-gain switch. I used this on my BAT preamp quite a bit and is very useful for multi-preamp systems
Click to expand...

Not sure what you mean by this. The JT is purely passive, so would this just be full volume?

Second, the ability to switch between multiple preamp outs, and thus control multiple amps / headphone amps. This way I can eliminate the necessity for having multiple volume controls in all my headphone amplifiers and push this functiona back in the chain... perhaps some strange bi-amping creation could be dreamed up as well, who knows.
Click to expand...

This is already handled by the Darwin, and will be in the next version as well.

Third, the ability have a buffered tape loop for chaining/sharing sources (either native, or via an add-on board like the JISBOS).
Click to expand...

Again, handled by the Darwin. it does not include a buffer, but easy to add your own in line.
 
#451
BrianDonegan said:

Not sure what you mean by this. The JT is purely passive, so would this just be full volume?
Click to expand...


On my BAT when you pressed the unity gain button, the whole preamp turned into a big buffer and you could pass the signal through the preamp outputs to another preamp... like for chaining with a HT receiver. The volume display didn't read 100% volume though, it usually read at like 81% volume.
 
#453
Hi, I'm wondering what is your experience with this type of volume control from the point of view of audio in a tube based chain. I have an ALPS black at the moment before an 5687 based line amp folloved by a 2A3 PSE amp.

I have planned to make a ladder on a 4 pole 24 position, but that is more difficult to remote control (I really need it now for different reasons).

I'm just about to finish a relay attenuator based on Jos's 100k resistor values. The input does not seem to go under 65k, which should be fine even for the 6072 ended AN M7 RIAA, and I would terminate the pot with a 470k.
 

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#455
any news about new uber controler kit
may I ask If the unit will do:
- manual and remote control of volume - Including rotation of motor pot (with universal or learning remote)
- lcd display
- are there additonal functions like mute or power on off
 
#456
The Uber controller is still in the works. We are trying to get the DAC stuff back in stock (minor tweaks) as it has the highest demand. Uber will be soon.

To answer your questions:
- It uses rotary encoders instead of a pot, and will do manual and remote control, no motorized pot.

- It will support (and optionally come with) an LCD (or PLED if we can find one again).

- Mute would have to be added to the JT relay board (another relay) and that is yet to be completed, so possible. Power on/off would be another module (power control module) which we have discussed several times, and would likely offer power control of multiple devices.
 
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