Hi Thompsontech,
Glad to hear all is well with the Yarra and Melbourne. Never thought to use a bulb tester on a preamp but I guess a short is a short! And you would have had quite an explosion from a backwards mounted electrolytic. Keep up the great work!
Regards,
X
Glad to hear all is well with the Yarra and Melbourne. Never thought to use a bulb tester on a preamp but I guess a short is a short! And you would have had quite an explosion from a backwards mounted electrolytic. Keep up the great work!
Regards,
X
Nice work Thompsontech! Glad to hear your Yarra/Melb is singing away 🙂
On a side note, I have the Elekit TU8200 integrated amp and enjoy that as well.
On a side note, I have the Elekit TU8200 integrated amp and enjoy that as well.
@X thanks pal and your never-ending patience with me. 🙂
@ al I have the 18v trannies, but was wondering what ideal rails are...
@V Yes, I love the 8600 it works very well and the headphone out is amazing as well.
When I get the odds and ends done, I post a couple pics. Thanks again to everyone and I'm on to the next build.
JT
@ al I have the 18v trannies, but was wondering what ideal rails are...
@V Yes, I love the 8600 it works very well and the headphone out is amazing as well.
When I get the odds and ends done, I post a couple pics. Thanks again to everyone and I'm on to the next build.
JT
Melbourne was designed around +/-24v as ideal. However, I have run mine at +/-30v and it still sounds and measures well. Dropping voltage may be an issue though as the sweet spot of minimum current through the input LTP may be too low. You want minimum 2mA through the pair.
@ X Okay, sounds good, I think I'm close now, after I get the odds done, I will go back and tweak a bit. If I remember right they were not all right at 24, but 23.XX to 24. With bourns in thee it's very easy to adjust and not twitchy at all.
I checked for DC and it was not worth mentioning. It's more quite than my TU-8600 and that thing is quite.
Nice job all around on the design there guys!
A couple of things for others who do the build.
1) Mind what has been said about grounding
2) None of the recommended choices for the potentiometers will work on the faceplate without turning the face down. I took a 9/16 and milled to allow for the nut and washer. THis turned out to be an additional 3.9mm from the existing hole. There is also an issue with the POT being way to low unless you stand it way off the HPA or raise the HPA. I chose to raise the HPA. Stand off your HPA to about 26mm will get you close with the riser on the HPA to Pot baord.
3) Using the heavy wire on the RCA (www.manleylabs.com was a bit tuff to get enough heat with the large gauge wire, so I went 18ga solid for both the ground and signal. I soldered the wire first leaving some extra there. I then installed 18mm standoffs to the chassis. Next, I put all the RCA through the PCB added the shoulder washers and then lifted them through the chassis and fasted the PCB to the standoffs and snugged them down. Next up is installing the washers on the outside of the chassis and putting the nuts on. No speacial nuts are needed with these RCAs. One everything is snugged down, go ahead and solder the signal and grounds. By doing it in this order, you don't have to worry about lengths and stresses when mounting. Everything is where it should be an not under undue stress. If anyone wants pics, let me know.
4) I'm big on stabilizing both case and components from vibration. The case is good, but I will be adding 8 tabs so the top and bottom covers can be screwed down on the front and back and not just the sides. I also, use some hot-glue to make caps more rigid ( and in general to stabilize them. Sometimes from one to another, sometimes it's just bit on the base, but I do not like caps that vibrate. I have been known to cause windows to breath. 🙂
That's all I can think of, for now, I'm just trying to give some back, with my limited knowledge, that's about all I have.
JT
J
I checked for DC and it was not worth mentioning. It's more quite than my TU-8600 and that thing is quite.
Nice job all around on the design there guys!
A couple of things for others who do the build.
1) Mind what has been said about grounding
2) None of the recommended choices for the potentiometers will work on the faceplate without turning the face down. I took a 9/16 and milled to allow for the nut and washer. THis turned out to be an additional 3.9mm from the existing hole. There is also an issue with the POT being way to low unless you stand it way off the HPA or raise the HPA. I chose to raise the HPA. Stand off your HPA to about 26mm will get you close with the riser on the HPA to Pot baord.
3) Using the heavy wire on the RCA (www.manleylabs.com was a bit tuff to get enough heat with the large gauge wire, so I went 18ga solid for both the ground and signal. I soldered the wire first leaving some extra there. I then installed 18mm standoffs to the chassis. Next, I put all the RCA through the PCB added the shoulder washers and then lifted them through the chassis and fasted the PCB to the standoffs and snugged them down. Next up is installing the washers on the outside of the chassis and putting the nuts on. No speacial nuts are needed with these RCAs. One everything is snugged down, go ahead and solder the signal and grounds. By doing it in this order, you don't have to worry about lengths and stresses when mounting. Everything is where it should be an not under undue stress. If anyone wants pics, let me know.
4) I'm big on stabilizing both case and components from vibration. The case is good, but I will be adding 8 tabs so the top and bottom covers can be screwed down on the front and back and not just the sides. I also, use some hot-glue to make caps more rigid ( and in general to stabilize them. Sometimes from one to another, sometimes it's just bit on the base, but I do not like caps that vibrate. I have been known to cause windows to breath. 🙂
That's all I can think of, for now, I'm just trying to give some back, with my limited knowledge, that's about all I have.
JT
J
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Is there a way to figure out the current running into the LTP without breaking into the circuit and running through my multimeter?
If 24V is the sweet spot, it doesn't appear the 15 volt transformers are a good match for the Melbourne's, as my rails are running just under 20. I'd like to figure out the current to see where I am at.
The only less than stellar response I am hearing from the Yarra / Melbourne combo is a somewhat lighter weight bass than I would normally hear through a solid state preamp. However, the thing measures pretty much flat as a pancake down to 10 Hz. Might running less than optimum 24V rails have anything to do with this, or does the extra voltage only play into overall gain? I don't need any more gain as I am running 99 dB efficient speakers.
Thanks
Measure voltage across R111 or R112 and use I=V/R
Light bass might be either your input or output capacitors not being big enough. But I recall Vunce had weak bass on his Alpha Nirvana when the LTP did not ha e enough current since the rails were low (temporary test transformer). An 18v trafo might be better - if you could rejigger the resistors at 20v to get 2mA.
Light bass might be either your input or output capacitors not being big enough. But I recall Vunce had weak bass on his Alpha Nirvana when the LTP did not ha e enough current since the rails were low (temporary test transformer). An 18v trafo might be better - if you could rejigger the resistors at 20v to get 2mA.
Hi Aljordan
During the Alpha Nirvana verification build I found that running to little current through the LTP did affect the sound similar to what you described with your Melbs. When I changed transformers to get the proper working dc voltage and current through the LTP the sound improvement was immediately noticeable 🙂
In the meantime if you cannot change your transformers on your Yarra PSU try building the PCA daughterboards, 20vdc is perfect for them and they sound excellent! I also use 99dB efficient speakers and the lower gain of the PCA’s (approximately 16dB) mates better than the Melbs with my combo.
Slick little solve for the extended input switch on the Yarra... pretty cheap and very nice looking.
You only need to drill the hole in the face plate slightly larger and glue in the bushing. You cut the rod to proper length and you need not worry about the thickness of the face, or mucking about with nuts and washers. If you can't visualize it, I can post some images if anyone wants them.
JT
https://www.amazon.com/gp/product/B072JPQX4Q/ref=ox_sc_act_title_1?smid=A1M8G92U41XEUX&psc=1
https://www.amazon.com/gp/product/B0159WOA4K/ref=ox_sc_act_title_2?smid=A35C93BBDX68G6&psc=1
https://www.amazon.com/gp/product/B01N9SBEHT/ref=ox_sc_act_title_3?smid=ATVPDKIKX0DER&psc=1
You only need to drill the hole in the face plate slightly larger and glue in the bushing. You cut the rod to proper length and you need not worry about the thickness of the face, or mucking about with nuts and washers. If you can't visualize it, I can post some images if anyone wants them.
JT
https://www.amazon.com/gp/product/B072JPQX4Q/ref=ox_sc_act_title_1?smid=A1M8G92U41XEUX&psc=1
https://www.amazon.com/gp/product/B0159WOA4K/ref=ox_sc_act_title_2?smid=A35C93BBDX68G6&psc=1
https://www.amazon.com/gp/product/B01N9SBEHT/ref=ox_sc_act_title_3?smid=ATVPDKIKX0DER&psc=1
Sorry, I am all out. Perhaps another member here who isn’t going to build theirs can sell/trade with you?
Is the purpose of the bushing to give it a more solid feel? I did something similar but didn't use a bushing. There is no side to side play, but i can push the knob a teeny bit because I didn't want the back face of the knob rubbing the indentation of the faceplate.