As far as I can tell it works no differently from any other power amp with a 12V trigger. What were you wanting?
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VTV Purifi 1ET400A updates
- Thread starter Rugger
- Start date
I was planning to have the purifi amp in a cabinet connected to the pre out and trigger from an avr , but also to be able to change cables and connect directly from the output of a dac. The issue is getting the amp to turn on when connected to the dac, but now I think of it, if the amp is in a cabinet swapping cables would also be a problem. Needs some more thought.
For those who might be better with the maths than myself, is the load created by this speaker one that the VTV Purifi will handle well?
https://www.stereophile.com/content/aerial-acoustics-10t-loudspeaker-measurements
https://www.stereophile.com/content/aerial-acoustics-10t-loudspeaker-measurements
Be a walk in the park, little dip to 3 Ohm shouldn't cause any concern.
I can confirm this problem.
I get the cell phone noises on mine quite often.
I found this thread searching for a solution...
Who made your amp?
according to Warren of vtv "This is the Purifi FE-02 front end. It has capacitive filter and GBW like the VTV" the hypex factory buffer doesn't have, as of this post they made some changes with the hypex factory buffer
i ordered mine and its on its way
Bumping this question since it was unanswered.
Yes. Or No. It would depend on the particular pieces of equipment and your expectations. I run three channels from my Denon AVR (unbalanced) to three channels of Purifi (balanced) with the standard Purifi input buffer gain. I have sufficient volume
The sensitivity doubles to 4V though which could introduce distortion and negate some of the benefit of the Purifi’s cleanness.
Sorry - I don't understand this. Please explain more.
No that is not correct. Todd, I thought I explained that to you before, if the power amp's input sensitivity is 2 V then just by using your AVR's unbalanced output with the XLR balanced input of a power amp using a good RCA to XLR cable as described in Hypex's data sheet will NOT suddenly cause the the input sensitivity of the power amp to double. And a RCA to XLR cable will not lose half the voltage either. Half the voltage is lost going from the balanced output to unbalanced output (if provided) in the final stage of a balanced preamp. Your AVR doesn't even have balanced output so it has nothing to lose to begin with. It is simple math to calculate input sensitivity from gain, and if you still don't believe, just take some measurements yourself. You only need a RCA to XLR cable and a multimeter, or read Hypex NC400's data sheet linked below.
You do have to make sure the cable is done as described in Hypex data sheet to minimize potential performance loss in terms of noise.
The double voltage, or half voltage talk are all about the unbalanced output vs balanced output voltage of a preamp. People got that confused with input sensitivity of power amps such as Purifi and Hypex that has a fixed gain. Some amps do have different gains for the unbalanced and balanced inputs by design, but not the Purifi and Hypex's and they typically only provide XLR inputs anyway.
You can also read page 17 of the Hypex dat sheet, and see that in the last paragraph it clearly states that:
"The output signal is the voltage difference between the RCA pin and the RCA shell. Since the cold (white) wire is not used to carry ground currents, the amplifier does indeed see the exact output voltage of the source." So no loss of voltage from your AVR's RCA outputs!
Again, if you have a prepro such as the AV7705, then yes if you are getting 2 V from the RCA output and you will get 4 V from the XLR outputs. That is not to be confused with the power amp's sensitivity. I don't know why this thing seems to have caused so much confusion, even among some who make those amps, apparently.. May be someone else would chime in and can explain it better than I can, hopefully..
NC400 04xx Datasheet (diyclassd.com)
On page 17:
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My post here was before we corrected the confusion in the PM. I forgot to go back afterward and delete this.No that is not correct. Todd, I thought I explained that to you before, if the power amp's input sensitivity is 2 V then just by using your AVR's unbalanced output with the XLR balanced input of a power amp using a good RCA to XLR cable as described in Hypex's data sheet will NOT suddenly cause the the input sensitivity of the power amp to double. And a RCA to XLR cable will not lose half the voltage either. Half the voltage is lost going from the balanced output to unbalanced output (if provided) in the final stage of a balanced preamp. Your AVR doesn't even have balanced output so it has nothing to lose to begin with. It is simple math to calculate input sensitivity from gain, and if you still don't believe, just take some measurements yourself. You only need a RCA to XLR cable and a multimeter, or read Hypex NC400's data sheet linked below.
You do have make sure the cable is done as described in Hypex data sheet and you will be fine.
The double voltage, or half voltage talk are all about the unbalanced output vs balanced output voltage of a preamp. People got that confused with input sensitivity of power amps such as Purifi and Hypex that has a fixed gain. Some amps do have different gains for the unbalanced and balanced inputs by design, but not the Purifi and Hypex's.
You can also read page 17 of the Hypex dat sheet, and see that in the last paragraph it clearly states that:
"The output signal is the voltage difference between the RCA pin and the RCA shell. Since the cold (white) wire is not used to carry ground currents, the amplifier does indeed see the exact output voltage of the source." So no loss of voltage from your AVR's RCA outputs!
Again, if you have a prepro such as the AV7705, then yes if you are getting 2 V from the RCA output and you will get 4 V from the XLR outputs. That is not to be confused with the power amp's sensitivity. I don't know why this thing seems to have caused so much confusion, even among some who make those amps, apparently.. May be someone else would chime in and can explain it better than I can, hopefully..
NC400 04xx Datasheet (diyclassd.com)
On page 17:
View attachment 152924
If he is not receptive to using an unfiltered outlet, would he be receptive to replace the Y cap filter with a X cap filter, if requested by the customer? Have you discussed that alternative/option with him? Also, do they have a phone number for customer support, or can only use the online form?
According to Hypex, their current version has input filter that should be sufficient for normal applications but can still pose a problem when used with dacs that have poorly designed output stages which do not have adequate filtering.Alan, thanks again!
Not sure why Hypex response was incorrect.
I specifically asked them about am/fm frequencies.
Question remain, is the buffer board the sold to OEMs such as VTV the same as what the used in/with the MP amplifier module boards? I'll try to find out.
Except maybe for the MP NCore, not sure what you want to know?
The stock buffers for the Hypex and Purifi are well documented and are different. Beyond that you can go with a custom buffer and what parts it uses and how it differs are dependent on the supplier.
I am talking about the one VTV calls stock "factory hypex buffer", if that is the one and only (if there are more than one then I would want to know which one has the input filter, hopefully there is just one, or they now all have the input filter) that hypex sells to OEMs; and has the specs as the one used in hypex's NC502MP then as long as they are using the current version, it should have the input filter. I am hoping to have a response by tomorrow.
If VTV’s reference is to the stock factory Hypex, it has no filter and uses LM4562 op-amps. The circuit is shown in the NC500 Eval board data sheet. According to the site, there is only the original rev. The MP amps have had several revs. Their buffer circuit is not in the respective data sheets and Alan March disputed the Hypex claim that they had filters. Have not seen a VTV Purifi amp with Hypex stock buffer, but I do own NC500s with it.
The stock Purifi (EDIT) buffer uses OPA1612 op-amps and the circuit is shown in the Eval1 data sheet.
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Thank you Rick, to avoid creating confusion I will PM you about my Q&A with hypex.
