Buckeye PURIFI 1ET400A Gain Issues

[kinghrothgar]

Got my Buckeye in recently only to realize I kinda fucked up and that my Denon X3700H doesn't have enough voltage on the preamp outs to fully utilize the amp. I'm having to run close to 0 db on the Denon and even having to go above 0 for some very quietly mixed content. Are there options for getting a bit more voltage added to the lines without degrading quality or breaking the bank? Effectively I'm looking for a preamp to put between the Denon and the Buckeye right?

 

[Chrispy]

Which Buckeye and does it have gain setting options?

ps nm, it's in your title and it seems to have multiple gain settings....

 

[kinghrothgar]

Which Buckeye and does it have gain setting options?

ps nm, it's in your title and it seems to have multiple gain settings....

Yep, I'm running it on the high gain settings. Even with that it's still running very quiet. From reading the review of the Denon, it starts clipping at 1.4 V. After noticing how high I was having to turn the Denon up I searched around ASR and realized that you need I believe 2.5 V to get the full wattage out of the Buckeye

 

[Chrispy]

Yep, I'm running it on the high gain settings. Even with it's still running very quiet. From reading the review of the Denon, it starts clipping at 1.4 V. After noticing how high I was having to turn the Denon up I searched around ASR and realized that you need I believe 2.5 V to get the full wattage out of the Buckeye

Denon should be good to 2V if not beyond, are you getting too much noise or something when you turn the volume up?

 

[mdsimon2]

25.5 dB isn't exactly high gain, especially with a 2 V input.

Just my opinion but if you don't have enough volume due to low source level, just crank the volume. I think it goes up to +18 dB? Even if you can't drive the amp to full power it still should get loud, and if it isn't loud that means you are feeding it a much lower level than 2 V. Because the source level is low, there isn't an issue with cranking the volume, other than potentially increased noise.

Michael

 

[Mnyb]

Can it be some processing and EQ adjustments in the AVR that’s using up,the headroom ?

I’m would not worry to much if I still have some travel left in the volume control it’s not pegged at the end stop yet .

yor probably not getting 2 volts with the volume control in the 0dB position with that quiet content .

So with very quiet content it would still not be problem , it’s not where the volume controls sticks but the actual signal level that counts .

 

[kinghrothgar]

I'm over thinking it / over optimizing. I read more about the Denon and was misunderstanding somethings. I have 18 more "db" of volume control left on the Denon where I'm usually running it. With the Denon amps off in preamp mode, it should be able to put out even well above 2 V from what I'm reading very cleanly. 1.4 V was with the amps on. I'll just let it ride until I actually notice distortion or clipping, which again, from my reading, I'm probably not gonna run into.

What started all this is that the Parasound A21 that the buckeye replaced (A21 is moving to rear duty) has significantly higher gain, but less overall RMS. I expected the buckeye with much more RMS to be louder at lower volume settings on the Denon because if forgot to factor in gain.

 

[amper42]

I'm over thinking it / over optimizing. I read more about the Denon and was misunderstanding somethings. I have 18 more "db" of volume control left on the Denon where I'm usually running it. With the Denon amps off in preamp mode, it should be able to put out even well above 2 V from what I'm reading very cleanly. 1.4 V was with the amps on. I'll just let it ride until I actually notice distortion or clipping, which again, from my reading, I'm probably not gonna run into.

What started all this is that the Parasound A21 that the buckeye replaced (A21 is moving to rear duty) has significantly higher gain, but less overall RMS. I expected the buckeye with much more RMS to be louder at lower volume settings on the Denon because if forgot to factor in gain.

You won't notice distortion with the Purifi on your Denon 3700. What you will notice is in Audyssey the volume setting for the speakers powered by the Purifi will be configured 3-4dB higher than those on the internal amps or on the Parasound A21. It's basically the difference between 25.5dB gain (Purifi) and 29dB (Denon internal amps/Parasound A21). It's not a big deal and the Purifi amp will still be running significantly cleaner than the Denon internal amps.

 

[LSUGopher]

I'm over thinking it / over optimizing. I read more about the Denon and was misunderstanding somethings. I have 18 more "db" of volume control left on the Denon where I'm usually running it. With the Denon amps off in preamp mode, it should be able to put out even well above 2 V from what I'm reading very cleanly. 1.4 V was with the amps on. I'll just let it ride until I actually notice distortion or clipping, which again, from my reading, I'm probably not gonna run into.

What started all this is that the Parasound A21 that the buckeye replaced (A21 is moving to rear duty) has significantly higher gain, but less overall RMS. I expected the buckeye with much more RMS to be louder at lower volume settings on the Denon because if forgot to factor in gain.

1. If you haven't already, I would rerun Audyssey to adjust the Purifi channels levels (If you haven't done that manually) due to the gain difference mentioned several times in this thread.

2. From what I have found the Parasound A51 has more clean power than the Purifi ET400A so your RMS comment above is confusing. The Parasound A51 per Sound & Vision (2012) tested at 301.1 watts @ 0.1% (8 Ohms) and 330.6 watts @1.0% (8 Ohms) (link below). The Parasound rated specs of 250X5 are around 0.02% distortion, while the Et400A module rated spec of 227 watts are at 1%. I would expect the A21 to be at least as good as the A51. The Purifi is cleaner at lower wattage, but power is not an advantage over the Parasound imo.

Parasound Halo P 7 Multichannel Preamplifier, A 51 Multichannel Amplifier & JC 1 Single-Channel Amplifier HT Labs Measures

HT Labs Measures Parasound Halo P 7 Multichannel Preamplifier Analog frequency response in Tone Off mode: –0.05 dB at 10 Hz –0.01 dB at 20 Hz –0.15 dB at 20 kHz –0.99 dB at 50 kHz Analog frequency response with Tone On, controls zeroed: –0.15 dB at 10 Hz –0.24 dB at 20 Hz –0.49 dB at 20 kHz

www.soundandvision.com

 

[kinghrothgar]

1. If you haven't already, I would rerun Audyssey to adjust the Purifi channels levels (If you haven't done that manually) due to the gain difference mentioned several times in this thread.

2. From what I have found the Parasound A51 has more clean power than the Purifi ET400A so your RMS comment above is confusing. The Parasound A51 per Sound & Vision (2012) tested at 301.1 watts @ 0.1% (8 Ohms) and 330.6 watts @1.0% (8 Ohms) (link below). The Parasound rated specs of 250X5 are around 0.02% distortion, while the Et400A module rated spec of 227 watts are at 1%. I would expect the A21 to be at least as good as the A51. The Purifi is cleaner at lower wattage, but power is not an advantage over the Parasound imo.

Parasound Halo P 7 Multichannel Preamplifier, A 51 Multichannel Amplifier & JC 1 Single-Channel Amplifier HT Labs Measures

HT Labs Measures Parasound Halo P 7 Multichannel Preamplifier Analog frequency response in Tone Off mode: –0.05 dB at 10 Hz –0.01 dB at 20 Hz –0.15 dB at 20 kHz –0.99 dB at 50 kHz Analog frequency response with Tone On, controls zeroed: –0.15 dB at 10 Hz –0.24 dB at 20 Hz –0.49 dB at 20 kHz

www.soundandvision.com

Mistype, I have the A23: 125 watts RMS x 2, 20 Hz - 20 kHz, 8 Ω, both channels driven

So about half the wattage of the 400A and a channel less

 

[restorer-john]

What started all this is that the Parasound A21 that the buckeye replaced (A21 is moving to rear duty) has significantly higher gain, but less overall RMS. I expected the buckeye with much more RMS to be louder at lower volume settings on the Denon because if forgot to factor in gain.

And yet another instance of low gain amplifiers being incompatible with typical preamp level outputs...

You need 26-29dB of voltage gain to have a reasonable range of volume with tpyical 1-2V output preamp levels or source levels.

I would contact buckeye and get a replacement/changeover front end board with more gain. I'm sure he could arrange something like that. Depending on how his boards are designed, it could be as simple as 2 or 4 resistors in the buffer gain stages.

 

[jamesdyson]

There seems to be a propensity for some manufacturers to have unusable low gain settings. The number of sources that output the 10volts rms or more to use these low gain settings is tiny. I can only assume they are trying to game and get to the top of the SINAD tables.

 

[amper42]

There seems to be a propensity for some manufacturers to have unusable low gain settings. The number of sources that output the 10volts rms or more to use these low gain settings is tiny. I can only assume they are trying to game and get to the top of the SINAD tables.

The RME ADI-2 DAC FS has plenty of gain to power the Purifi amp at lower gain settings with the Revel F328Be. I tried all three settings and found I could not hear any difference except the obvious volume drop with lower gain. That being said I currently prefer my Boxem Arthur 4215/2E set at high gain 27.2dB versus medium at 20.8dB. I can't hear a difference in SINAD, but the high gain sounds a bit more dynamic to me. All AVR users will want to use high gain and even 4V balanced DAC setups may prefer it too.

Personally, I can't think of a reason to use the low gain 12.8dB setting except for stretching the SINAD specs during testing or perhaps where you are using a questionable DAC as a preamp and it has a history of forgetting it's last volume setting.

And while talking about not hearing a difference. If you're strapped for cash and want to save money get the Buckeye Hypex NC502MP for $695 instead of paying hundreds more for a Purifi. If you can reliably tell a difference between the Purifi and the NC502MP in an AB test without touching the amp to check for heat then your ears are much better than mine.

 

[GXAlan]

There seems to be a propensity for some manufacturers to have unusable low gain settings. The number of sources that output the 10volts rms or more to use these low gain settings is tiny. I can only assume they are trying to game and get to the top of the SINAD tables.

Exactly, or even the published THD or noise specifications.

The vintage Sony TA-N9000ES outperforms the HypeX NC252MP when paired with the Yamaha CX-A5100 when trying to hit 10W output because you leave the sweet spot of the Yamaha which starts to fade at around 1V output rather than 2V. But at those voltages, it beats the Monolith HTP-1.

Gain matching is so important and it gets overlooked because of Benchmark AHB2 throwing the gauntlet.

I don’t think user selectable gain is a bad thing and there’s no question that with time, low gain amps and high output sources are the best option — but during this transition period, it’s nice to have control. There’s also the question if stuff like AES67 and active speakers will end up become the mainstream options.

Today it is AVR -> AVP/amp -> AVP/analog active speakers <-> AVP/AES67. Based upon how well integrated fully active speakers can perform, you might end up with a world where the AVP/amp is a lot less popular than it is today (which is in itself a niche).

The big limitations are power. Run a 16 channel passive speaker setup and you run 16 x 16 awg two wire cables. With a 16 channel active speaker setup and now you have to deal with 16 sources for AC power and the appropriate way to trigger them on/off.

I personally believe that 5 wire 48V (analog audio with DC power) and Neutrik PowerCon20 are good ways to control power. I wonder PoE combined with more efficient speakers and super capacitors can provide another alternative.

 

[goryu]

I would contact buckeye and get a replacement/changeover front end board with more gain. I'm sure he could arrange something like that. Depending on how his boards are designed, it could be as simple as 2 or 4 resistors in the buffer gain stages.

Would indeed be nice if that were possible....

 

[jamesdyson]

The RME ADI-2 DAC FS has plenty of gain to power the Purifi amp at lower gain settings with the Revel F328Be. I tried all three settings and found I could not hear any difference except the obvious volume drop with lower gain. That being said I currently prefer my Boxem Arthur 4215/2E set at high gain 27.2dB versus medium at 20.8dB. I can't hear a difference in SINAD, but the high gain sounds a bit more dynamic to me. All AVR users will want to use high gain and even 4V balanced DAC setups may prefer it too.

Personally, I can't think of a reason to use the low gain 12.8dB setting except for stretching the SINAD specs during testing.

Yes, the rme is one of the few. I commented in a buckeye thread the other day. It's highest gain setting of 25.5dB is too low for a 2vot rca source to drive the amp to full power. My maths is not good but I think that works out a about 350 watts instead of the rated 750 watts.

 

[Sokel]

The "trick" for getting nice numbers is low gain for the power amp and a clean pre-stage with hefty output.
All these input buffers are exactly that,a pre of some short (and it would be good to know their input clamp voltage too) .

What exactly stops them from being SOTA like a nice external pre so they can give the desired gain while maintaining a healthy input impedance?
It's a trade off and the best way for users is having a rough way to measure it as system rather than just separate devices.