[BoilermakerFan]

Quote:

Originally Posted by rhester /img/forum/go_quote.gif Who has tried the OptiVol with the Max? I am wanting to try one but don't know where to pull power from. Any help without reading way too many pages.

I have the OptiVols for the MAXes, but I haven't cased any of mine up or had a chance to get my 3 boards populated. If the tube LEDs and LED resistor positions are jumpered then there will be 27VDC at the center tap. You will need to tell Greg at SKA that your OptiVol is for a MAX with 0-27VDC so he can provide the correct resistors for the power to the OptiVol.

Maybe Tom or somebody else can confirm what voltage would be present at the center LED position if the tube LEDs are used. I don't want to assume it is 27VDC if all the LEDs are wired in series.

I know a couple of the guys used them with their 24V Aikido builds and I plan to use an OptiVol on my 24V Aikido as well as the MAXes, so I need to order two more kits. FWIW, the potentiometer on the OptiVol is 100K Log, not 50K Log, but I forgot to ask Greg what happens if a 50K is used in the circuit...

 

[soloz2]

Yep, I've got a Max with an OptiVol and I highly recommend it! great attenuator for the money. Just let Greg know that you plan to use it with a Max (27v) and he'll help you out. I just received a second over the weekend for a second Max.

If you jumper the RLEDs (R5 if I remember correct...) then you get 27v.

 

[BoilermakerFan]

Hey guys, just wanted to let you know that the US dollar has gotten stronger against the OZ dollar so the OptiVol kits are now ~$17.50 shipped. Greg also made some improvements to the design so the LED is now constant powered and it has a little more attenuation range.

My wife is putting me under the gun to have the DR console refurb'ed by Thanksgiving since we're hosting this year. That means I won't be able to fully complete my DB comparisons until after T-day. I'm setting up the MAX in this build so I can easily remove it to complete my testing.

I also now have a pair of Yamaha YH-3 orthodynamic headphones to test with in addition to my K601s.

 

[BoilermakerFan]

Oh, if anyone does decide to order an OptiVol or kit, be sure to let greg know it's going on a MH MAX with a 0-27VDC power source so he can include or use the correct resistors.

 

[pinkfloyd4ever]

Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif Hey guys, just wanted to let you know that the US dollar has gotten stronger against the OZ dollar so the OptiVol kits are now ~$17.50 shipped. Greg also made some improvements to the design so the LED is now constant powered and it has a little more attenuation range.

NIIIICEEE, I'm gonna use one on my speaker amp build...guess I need to get my sh!t together and figure out which one so I know what voltage to tell him i'll be using when I order
anyone know if a gainclone kit from audiosector or chipamp.com can power an optivol? I would guess that it would work, but has anyone here done it?

 

[BoilermakerFan]

Quote:

Originally Posted by pinkfloyd4ever /img/forum/go_quote.gif NIIIICEEE, I'm gonna use one on my speaker amp build...guess I need to get my sh!t together and figure out which one so I know what voltage to tell him i'll be using when I order anyone know if a gainclone kit from audiosector or chipamp.com can power an optivol? I would guess that it would work, but has anyone here done it?

I have Peter's Premium GC amp kit for my console refurb. I'll be using a 300VA toroid to feed the two mono PSUs. I'm using my MAX as the preamp to power the OptiVol. You can either make your own small PSU with a PCB from Greg or determine the voltage you plan to use for your GC and let Greg know that output from the gainclone PSUs. I'll be using 22VAC secondary which translates to 35VDC, IIRC, but you might want to confirm with Peter via email. Both Greg (SKA) and Peter (AudioSector) have been a great help over the months as this project has progressed.

What I really like about the OptiVol is the factthat the pot isn't in the signal path, so you can remotely mount I away from the OptiVol PCB and keep the actual signal paths as short as possible.

Off topic, but I've also been working with Greg to use two OptiVols controlled by one 50K ALPS pot for a balanced setup. There are a couple of components that might need to be tweaked to get the correct attenuation range, but it should work well enough to allow me to build a balanced attenuator for about $50.

Does it track as well as stepped attenuator? No, but it's continuously variable and 20% the cost too so I can deal with small tracking errors in the ALPS pot. A single gang 50K pot could also be used with the component changes, but Greg includes the 100K pots so it kind of a moot point outside of the balanced setup.

 

[manaox2]

Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif Oh, if anyone does decide to order an OptiVol or kit, be sure to let greg know it's going on a MH MAX with a 0-27VDC power source so he can include or use the correct resistors.

Good news! I guess since the JT Attenuator is taking the better part of a year at least to be released I'm going to have to go that route soon.

 

[BoilermakerFan]

Man, I had nice reply all typed up and it didn't post up, I received a page load error instead.

So long post cut short... The JT with AC1 will cost more than the MAX itself. Now if the goal is to use the additional flexibility and power of the AC1 and VFD to display other info such as artist and track title or run other firmware tweaks like cross feed (if possible) than I can see the value, but for just volume attenuation, I can't see how the standard ALPS or OptiVol would be lacking much behind the JT.

 

[manaox2]

Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif Man, I had nice reply all typed up and it didn't post up, I received a page load error instead. So long post cut short... The JT with AC1 will cost more than the MAX itself. Now if the goal is to use the additional flexibility and power of the AC1 and VFD to display other info such as artist and track title or run other firmware tweaks like cross feed (if possible) than I can see the value, but for just volume attenuation, I can't see how the standard ALPS or OptiVol would be lacking much behind the JT.

I'm making a balanced boutique millett max with an internal OPUS DAC.

I have a millett max with an ALPs too, they seem to be a good value for it.

 

[pinkfloyd4ever]

holy crap, why didn't anyone tell me touching 2 of the metal tabs of the rectifier diodes together is a bad idea?

I'm just surprised I haven't heard of anyone else doing it. For those who are wondering exactly what happens, its similar to what happens when shorting a lead-acid battery, although I wouldn't recommend doing that either....not that I've ever done it

Anyway, this actually happened last night. I've been using it for a few periods of a couple hours today and everything seems ok, and measures the same as before, but is there a chance I messed anything up?

 

[cetoole]

It has been done, Pinkie, though obviously, never by me.

It turns out also to be a bad idea to accidentally touch one of the diode tabs to the uninsulated portion of the AC input jack, though again, something I would never do.

Finally, licking the tabs of the rectifiers while on is a REALLY bad idea. I really never tried this one though.

I would just monitor it for a bit, and if everything remains the same, I would be hopeful that you got away with it this time.

So, any guesses why we moved to recommending axial rectifier diodes for the minimax? The ones we specify for that though dont fit the regular max board, yet.

 

[pinkfloyd4ever]

Quote:

Originally Posted by cetoole /img/forum/go_quote.gif Finally, licking the tabs of the rectifiers while on is a REALLY bad idea.

LMAO, I guess I'm not the only one then, Colin

 

[manaox2]

Quote:

Originally Posted by cetoole /img/forum/go_quote.gif Finally, licking the tabs of the rectifiers while on is a REALLY bad idea. I really never tried this one though.

I thought of that when looking at your avatar.

 

[BoilermakerFan]

Small progress today, I finished matching my small signal transistors at lunch. I ended up with a total spread of 20 points on one BJT combo, a 17 point spread on the other BJT combo, and 6 point spread across all transistors for the MOSFET-MAX. All the CCS transistors are identically matched quads.

I am very, very tempted to order a MiniMAX board for the MOSFET-MAX for the better ground plane, but my concern is the closer spacing of components with my relatively high bias currents. I will be implementing the other changes to my MAX boards as mods, so the big difference will be the ground plane.

We're hosting Thanksgiving this year, so I have a few other pressing projects to complete before next week, so building will FINALLY commence the weekend after when all the company is gone. Or I might just

for a while in the basement, but I suspect the smell of solder will give me away... LOL!

 

[tomb]

Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif Small progress today, I finished matching my small signal transistors at lunch. I ended up with a total spread of 20 points on one BJT combo, a 17 point spread on the other BJT combo, and 6 point spread across all transistors for the MOSFET-MAX. All the CCS transistors are identically matched quads. I am very, very tempted to order a MiniMAX board for the MOSFET-MAX for the better ground plane, but my concern is the closer spacing of components with my relatively high bias currents. I will be implementing the other changes to my MAX boards as mods, so the big difference will be the ground plane. We're hosting Thanksgiving this year, so I have a few other pressing projects to complete before next week, so building will FINALLY commence the weekend after when all the company is gone. Or I might just for a while in the basement, but I suspect the smell of solder will give me away... LOL!

The regular MAX board is still the preferred choice for a MOSFET-MAX.