Russ White said:Thanks motherone. I got your payment. I too can't wait to see what come out of the preamp thread. Listening to that thing now.It makes a super headphone amp.
I have some similar headphone amps (the MINT, PIMETA, and PPA, from the folks at head-fi), so I'm very familiar with the sound. That said, only maybe the mint would be decent as a preamp, and all it's chips are SMD (so parts aren't easily rolled).
I'm hoping for a larger board so that I can construct a nice chassis around it with a quality, large, volume control
But yeah, the BUF634/OPA627 is only bested by my PPA's, one that has 2x OPA637's and 1x OPA627 (ground channel) driving diamond buffers, and another that has the same opamps, but driving quad elantec buffers on each channel.
Unfortunately I cannot use USPS Global Priority to Italy.
However, I do believe I can send orders to Italy USPS Airmail Letter Post, and if so they will be at the same cost as the other international orders. Which is $6.00 for the first PCB and $1.00 for aditional boards.
I will try it this way. So just go ahead an use the international button on the order page.
EDIT: Forgot to mention that the price for each board is $19.75
However, I do believe I can send orders to Italy USPS Airmail Letter Post, and if so they will be at the same cost as the other international orders. Which is $6.00 for the first PCB and $1.00 for aditional boards.
I will try it this way. So just go ahead an use the international button on the order page.
EDIT: Forgot to mention that the price for each board is $19.75
Pre-amp for Ref board
I've been thinking about building the M3 (http://www.amb.org/audio/mmm/ ) as a headphone amp and pre-amp for this ref board. It is similiar to the PPA with a ground channel but uses mosfets. Would this be an acceptable/ideal choice? Why would a MINT be more suited for pre-amp duty over the PPA or PIMETA?
thanks for any info
I've been thinking about building the M3 (http://www.amb.org/audio/mmm/ ) as a headphone amp and pre-amp for this ref board. It is similiar to the PPA with a ground channel but uses mosfets. Would this be an acceptable/ideal choice? Why would a MINT be more suited for pre-amp duty over the PPA or PIMETA?
thanks for any info
About headphone amps as preamps.
Hi Greg,
I am not as experienced as some, but I will tell you what I know from experience.
Some headphone amps make fine preamps(MINT, CMOY), some very certainly do not, at least not without some modifications which essentially make them something other than what they were.
Example of poor choice for preamp duty include PPA/Pimeta and probably any other headphone amp with a dedicated output ground channel. The reason (as I understand it) is that those type of amps must drive a "passive" load to the be stable, in otherwords the output ground is in isolation. When you drive an "active" load like a power amp you run the risk of making your headphone amp unstable or worse... Ouch. I know this as I fried my SORTAPIMETA clone exactly this way.
I hope that helps.
Hi Greg,
I am not as experienced as some, but I will tell you what I know from experience.
Some headphone amps make fine preamps(MINT, CMOY), some very certainly do not, at least not without some modifications which essentially make them something other than what they were.
Example of poor choice for preamp duty include PPA/Pimeta and probably any other headphone amp with a dedicated output ground channel. The reason (as I understand it) is that those type of amps must drive a "passive" load to the be stable, in otherwords the output ground is in isolation. When you drive an "active" load like a power amp you run the risk of making your headphone amp unstable or worse... Ouch. I know this as I fried my SORTAPIMETA clone exactly this way.
I hope that helps.
Re: Pre-amp for Ref board
You can use them as a preamp with some modifications, however you're better off building a dual supply for it and removing the ground channel entirely.
On the Pimeta, PPA and m3, they have a TLE2426 railsplitter that creates a virtual ground. This is then fed to an opamp and buffered by various means (BUF634 or Pimeta, Elantec buffer on PPA v1/1.1, Diamond Buffer on PPA2, and Class-A output stage on the m3). This is implemented becuase the buffered ground line is designed to sink the return currents from a headphone.
Since you won't/shouldn't have massive return currents on a preamp, it because more of a liability than a benefit. If you create a dual power supply and don't populate the ground channels, I think the Pimeta, PPA and m3 would work fine. But if you wanted double-duty as a headphone amp and preamp, I think you're sacrificing too much at that point.
There was a thread recently on head-fi about this very subject.
The mint might be better because if you build a dual supply for it, there's no need to worry about not populating the ground buffers -- it doesn't use any. It's essentially a dual opamp with two buf634's.
Gmorris said:
You can use them as a preamp with some modifications, however you're better off building a dual supply for it and removing the ground channel entirely.
On the Pimeta, PPA and m3, they have a TLE2426 railsplitter that creates a virtual ground. This is then fed to an opamp and buffered by various means (BUF634 or Pimeta, Elantec buffer on PPA v1/1.1, Diamond Buffer on PPA2, and Class-A output stage on the m3). This is implemented becuase the buffered ground line is designed to sink the return currents from a headphone.
Since you won't/shouldn't have massive return currents on a preamp, it because more of a liability than a benefit. If you create a dual power supply and don't populate the ground channels, I think the Pimeta, PPA and m3 would work fine. But if you wanted double-duty as a headphone amp and preamp, I think you're sacrificing too much at that point.
There was a thread recently on head-fi about this very subject.
The mint might be better because if you build a dual supply for it, there's no need to worry about not populating the ground buffers -- it doesn't use any. It's essentially a dual opamp with two buf634's.
Hi all-
I've been trying to get my sh!!t together with the parts kit, and I think I am about ready. Just wanted to post what I am thinking for preliminary feedback.
I am looking at Panasonic film caps, Sanyo EL's (AX-series very loe impedence, long life), and KOA Speer resistors. Here's my reasoning...
The Panasonic film caps are very good quality, and readily available from DigiKey.
The Sanyo caps are low ESR, have a great source for them, and they would save a little over $5 US per kit (the only non-AX would be the 10KuF snap ins, which are 50PL10000DAC for $4.29 each).
I looked at all sorts of resistors, but the hole spacing on the board is the real limiting factor. The body of Dale RN's is the same or slightly longer than the hole spacing on the board. Phoenix are much smaller (too small?), but are pricey. The KOAs are a solid middle ground.
I will be using Vishay-Dale PRO1's for the 1W's. Also, I will probably replace the 7W with 5W output resistors, as they shoudl be plenty big and offer a much wider selection. (The 7W I have found have the same problem as the 1/4W, in that they are as big as the hole spacing, and would not fit well.)
Feedback please? The only preliminary numbers I have are for the caps ($20.27 per kit, assuming 10 kits). Guessing the complete kit will be in the $45-50 range for everything. As soon as I get feedback I will calculate it all out.
Also, can we get an estimate of how many people would be interested in the kits, as that really determines the price.
Thanks!!
I've been trying to get my sh!!t together with the parts kit, and I think I am about ready. Just wanted to post what I am thinking for preliminary feedback.
I am looking at Panasonic film caps, Sanyo EL's (AX-series very loe impedence, long life), and KOA Speer resistors. Here's my reasoning...
The Panasonic film caps are very good quality, and readily available from DigiKey.
The Sanyo caps are low ESR, have a great source for them, and they would save a little over $5 US per kit (the only non-AX would be the 10KuF snap ins, which are 50PL10000DAC for $4.29 each).
I looked at all sorts of resistors, but the hole spacing on the board is the real limiting factor. The body of Dale RN's is the same or slightly longer than the hole spacing on the board. Phoenix are much smaller (too small?), but are pricey. The KOAs are a solid middle ground.
I will be using Vishay-Dale PRO1's for the 1W's. Also, I will probably replace the 7W with 5W output resistors, as they shoudl be plenty big and offer a much wider selection. (The 7W I have found have the same problem as the 1/4W, in that they are as big as the hole spacing, and would not fit well.)
Feedback please? The only preliminary numbers I have are for the caps ($20.27 per kit, assuming 10 kits). Guessing the complete kit will be in the $45-50 range for everything. As soon as I get feedback I will calculate it all out.
Also, can we get an estimate of how many people would be interested in the kits, as that really determines the price.
Thanks!!
Wow! Great work Brian,
I will very likely be in for a kit of parts.
I have some inquiries in with a couple of sourcing agents. And have gotten some preliminary quotes. From Singapore I got a quote of $28 per set, but that is if I buy 50 sets!
Not sure that many people want them.
I also have an inquiry in with futurlec, and they say they can source all the original parts (including the exact Wima film caps) except the rectifier and the relay.
I think your choice of parts is just fine. I would just want to be sure that those 5W resistors really are enough. I do trust you, I just am not sure how to calculate it.
Thanks,
Russ
I will very likely be in for a kit of parts.I have some inquiries in with a couple of sourcing agents. And have gotten some preliminary quotes. From Singapore I got a quote of $28 per set, but that is if I buy 50 sets!
Not sure that many people want them.I also have an inquiry in with futurlec, and they say they can source all the original parts (including the exact Wima film caps) except the rectifier and the relay.
I think your choice of parts is just fine. I would just want to be sure that those 5W resistors really are enough. I do trust you, I just am not sure how to calculate it.
Thanks,
Russ
Hi Russ-
I'm not sure either, but I took at look at the Leach amp part list (100-120w/ch) and it uses 2-5W resistors, so I figure it's enough. Many of the resistors in that class (well, the ones I looked at) can deal with many times their rated wattage in bursts. I think it'll be fine.
If people have interest in the cheapest kits possible, I could definitely reexamine my choices. I was looking for a solid/low cost combination.
I'm guessing we can get 10 kits, so am using volume pricing according to that. 20+ would be even cheaper, but I doubt there will be that many, at least until people have feedback on the amp.
-b
I'm not sure either, but I took at look at the Leach amp part list (100-120w/ch) and it uses 2-5W resistors, so I figure it's enough. Many of the resistors in that class (well, the ones I looked at) can deal with many times their rated wattage in bursts. I think it'll be fine.
If people have interest in the cheapest kits possible, I could definitely reexamine my choices. I was looking for a solid/low cost combination.
I'm guessing we can get 10 kits, so am using volume pricing according to that. 20+ would be even cheaper, but I doubt there will be that many, at least until people have feedback on the amp.
-b
parts selection
From post 51, Russ said:
...futurlec, ... they can source all the original parts (including the exact Wima film caps) .....
I have an interest in building an amp with Mauro's recomended parts. How many others do? Would someone be so brave as to venture an opinion on the value of that?
From post 51, Russ said:
...futurlec, ... they can source all the original parts (including the exact Wima film caps) .....
I have an interest in building an amp with Mauro's recomended parts. How many others do? Would someone be so brave as to venture an opinion on the value of that?
The honest truth is that as long as the components are of good quality we should have great sounding amps. I don't really think it's too important to have the exact parts (even Mauro has told me so) so I would not emphasize it too much. I think its more important that the parts be affordable and accessible to the average DIYer.
The only real advantage of using the actual parts is that you can be absolutely sure they will fit properly on the board. But you can ensure that in other ways too.
I am looking at selling these boards/kits long term, so I am considering all options. But I will likely buy a kit from Brian (if he deems it worth his while) for building my first board.
The only real advantage of using the actual parts is that you can be absolutely sure they will fit properly on the board. But you can ensure that in other ways too.
I am looking at selling these boards/kits long term, so I am considering all options. But I will likely buy a kit from Brian (if he deems it worth his while) for building my first board.
You know that is not a supporter of the theories on the absolute quality of the component production ( praies am dealing me of other theories, but sooner or later even will face this matter ).
From the statistic point of view, you have was probability of a good audio quality by choosing the only components base on the cost and to the availability, because is not demonstrable that a component more expensive gives automatically of the better audio results.
I have built my prototypes with the material that I had in house. in the MyRef case, consider that it is a continuous working process, for which worry you ( per hour ) of the components.
Reserve you the changes for the future personalizations!
Ciao
Mauro
From the statistic point of view, you have was probability of a good audio quality by choosing the only components base on the cost and to the availability, because is not demonstrable that a component more expensive gives automatically of the better audio results.
I have built my prototypes with the material that I had in house. in the MyRef case, consider that it is a continuous working process, for which worry you ( per hour ) of the components.
Reserve you the changes for the future personalizations!
Ciao
Mauro
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