Hello future builders,
only rear plate silkscreen missing.
We´ll have two front plate version, one for the preamplifier and one for the HPA (with XLR jack in front).
Question: it´s possible to publish here on the forum ZIP including eDrawing greater then 3MB?
JP
only rear plate silkscreen missing.
We´ll have two front plate version, one for the preamplifier and one for the HPA (with XLR jack in front).
Question: it´s possible to publish here on the forum ZIP including eDrawing greater then 3MB?
JP
Attachments
X, JP, Vounce, and Hugh, this has been an amazing process to watch! As a noob, I’m ever trying to learn what I can when I can. But I find myself looking for answers with in the text that must be elementary to you all. Like I’m almost done with a F5T v2 build and had planned on building the Mezmerize pre to drive it. I have the board and chassis. Also I have the boards for a M2X. Now I’ve received four Melbourne boards and I’m on the list for the Ybarra and chassis, hahah. What to do...?
What I’m not grasping is “coupling”, input gain needed, and input impedance needed for these amps.
I will have two separate systems at some point after I get on with building speakers for them this summer. One will be for our living room, and the other for my cave.
There will be a phono pre build down the line too, pearl 2, Muffsy, choices choices...
I want to set the Yarra up correctly but I’m not sure which amp to use it with. I like the HPA/pre option with the switch. That would be a great WAF feature for nighttime listening sessions.
Any input would be great. I’ve learned a lot, but have so to learn.
What I’m not grasping is “coupling”, input gain needed, and input impedance needed for these amps.
I will have two separate systems at some point after I get on with building speakers for them this summer. One will be for our living room, and the other for my cave.
There will be a phono pre build down the line too, pearl 2, Muffsy, choices choices...
I want to set the Yarra up correctly but I’m not sure which amp to use it with. I like the HPA/pre option with the switch. That would be a great WAF feature for nighttime listening sessions.
Any input would be great. I’ve learned a lot, but have so to learn.
Hi TboneAK,
These amps typically have pretty high input impedance of 100k or so, almost anything can be used to drive them.
If using Melbourne with M2X you will have 16.8dB if gain on Melbourne and combined with 15dB native gain on the M2X (via Edcors), gives you about 31.8dB of overall gain - enough to hit clipping with most sources. The gain on M2X is easily adjustable with your choice of the feedback shunt resistor.
As for Yarra, the gain is what you set it as in Melbourne. Default is 16.8dB but like for the M2X application can be adjusted. The F5 and variants are also circa 15dB gain I believe. So the Yarra should be able to drive it well too.
To set gain G=(R118+R119)/R118. Leave R119 set at 33k and so if you want to use the Yarra to drive a 0dB gain power buffer amp like a MoFo, or F4, etc. the gain should be at least 27dB to 29dB in order to be able to hit clipping. Setting R118 to 1k2 gives you 29dB if gain.
A value of 6k8 for R118 gives you 15.3dB, which is slightly less than 16.8dB when using R118 value of 5k6.
https://www.diyaudio.com/forums/att...-daughterboard-m2x-melbourne-tht_sch_002b-pdf
These amps typically have pretty high input impedance of 100k or so, almost anything can be used to drive them.
If using Melbourne with M2X you will have 16.8dB if gain on Melbourne and combined with 15dB native gain on the M2X (via Edcors), gives you about 31.8dB of overall gain - enough to hit clipping with most sources. The gain on M2X is easily adjustable with your choice of the feedback shunt resistor.
As for Yarra, the gain is what you set it as in Melbourne. Default is 16.8dB but like for the M2X application can be adjusted. The F5 and variants are also circa 15dB gain I believe. So the Yarra should be able to drive it well too.
To set gain G=(R118+R119)/R118. Leave R119 set at 33k and so if you want to use the Yarra to drive a 0dB gain power buffer amp like a MoFo, or F4, etc. the gain should be at least 27dB to 29dB in order to be able to hit clipping. Setting R118 to 1k2 gives you 29dB if gain.
A value of 6k8 for R118 gives you 15.3dB, which is slightly less than 16.8dB when using R118 value of 5k6.
https://www.diyaudio.com/forums/att...-daughterboard-m2x-melbourne-tht_sch_002b-pdf
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X, this hobby makes me smile, thanks for the lesson! That clears it up for the input gain and impedance. Any combo of amps and preamps I’m going to build will, sweet! I’m thinking the Yarra will have cave duty, and the Mez in the living room.
With the Yarra at its default output gain of 16.8dB, would that be enough to drive a set of 67ohm headphones? I’d like to build it with a switch for both option like in the schematic.
So how about coupling? Is there something I could read about that? It’s comes up often in these threads, but it’s still a gray area. DC couples or not DC coupled, are common comments. I though may I was starting get the concept, but then a few posts ago AC coupling was mentioned....
Thanks again for the help, and all the effort you guys are putting into these DIY projects! It’s really quite amazing.
With the Yarra at its default output gain of 16.8dB, would that be enough to drive a set of 67ohm headphones? I’d like to build it with a switch for both option like in the schematic.
So how about coupling? Is there something I could read about that? It’s comes up often in these threads, but it’s still a gray area. DC couples or not DC coupled, are common comments. I though may I was starting get the concept, but then a few posts ago AC coupling was mentioned....
Thanks again for the help, and all the effort you guys are putting into these DIY projects! It’s really quite amazing.
16.8dB is a pretty good gain setting for moderate sensitivity headphones. For 105dB+ headphones, you may want to bring it down. I have tested with 55ohm 96dB headphones at 41mA bias current and it works very well. You can really improve headphone only performance if you change the bias current to 100mA and drop the voltage rails to +/-15v (to reduce dissipation) and this will drive even 30ohm cans. I am posting that schematic below for the mods for an HPA if you are interested. It can still be used as preamp on most 15dB or higher sensitive amps but not on 0dB 25w amps like F4.
Here is HPA centric schematic for Melbourne. Switch the KSA1381 for TTA004B in order to handle higher current .
Here is HPA centric schematic for Melbourne. Switch the KSA1381 for TTA004B in order to handle higher current .
Attachments
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Hi Vunce,
The rain hit pretty hard but we just sat on the beach getting rained on for 10 min and it passed. It’s not like we can’t get wet as we are already in swim wear on the beach. A lot of green colored rain clouds that dump a lot of water. Back home when sky shows a green cloud it usually means tornados.
X
The rain hit pretty hard but we just sat on the beach getting rained on for 10 min and it passed. It’s not like we can’t get wet as we are already in swim wear on the beach. A lot of green colored rain clouds that dump a lot of water. Back home when sky shows a green cloud it usually means tornados.
X
