Buffalo II & transformers

[Joe Rasmussen]

Originally Posted by GaryB

It's similar to the buffer that Joachim Gerhard suggested in this ES9022 thread Anybody using the new ESS Vout DAC (ES9022)?

---Gary

The link to the post showed two schematics and naughtily I sort of added/ameded one a bit... hope nobody is offended. This is basically a solid state version of our Super Linear Cathode Follower, so we can call it a Super Linear Fet Follower.

Cheers, Joe

[GaryB]

Originally Posted by Joe Rasmussen

The link to the post showed two schematics and naughtily I sort of added/ameded one a bit... hope nobody is offended. This is basically a solid state version of our Super Linear Cathode Follower, so we can call it a Super Linear Fet Follower.

Cheers, Joe

Joe,
Any comments on the benefits of the SLCF compared to the simple cascoded source follower circuit that I use? This is the 2nd transformer output Buffalo DAC that I've built. The first one used 1:1 transformers and a bipolar diamond output buffer. And it was based on the original ES9008 Buffalo kit with simpler power supplies. This new version has better supplies, newer ESS chip, low value resistive loading to ground (thanks Joe), step up transformers, and the FET buffer. It sounds much "fuller" than the first version. Both have great detail but the first one was a bit lacking in body. This version seems to have fixed that and is very enjoyable.

---Gary

[Joe Rasmussen]

Originally Posted by GaryB

Joe,
Any comments on the benefits of the SLCF compared to the simple cascoded source follower circuit that I use?
---Gary

Hi Gary

I don't want to draw the wrong conclusion, but if you are using the fet follower with the constant current source and not the bootstrapped device I am showing, then there is quite a difference. Essentially the SLFF (and SLCF) runs in both constant current and constant voltage modes. It is common to see the CCS - but its also important that the actual follower element sees a constant voltage. What in reality is happening is that input (Grid or Gate), the output (Cathode or Source) and static element (Anode or Drain) are all seeing the same AC signal. Normally followers are one hundred feedback devices, you are using a trick to alters that state.

This is a quote from another forum:

"Good to hear from you John. It is really fun to watch the SLCF in action. If a 10.00 Vrms signal is applied to the grid, there will be a 10.00 Vrms signal coming out of the cathode, and the plate will also be following along with the 10.00 Vrms signal. They all move together as one. There is no gain or loss of signal, from in to out.... Paul Speltz"

Cheers, Joe

[chi0001]

anyone can help me?
i have a output transformer, and i want to connect it to buffalo 3 dac o/p, here is the pic, which no.1,2,3 is correct?

[reactivepower]

Originally Posted by reactivepower

I have an Emotiva amp that it is used with that has high gain so I needed to step down the signal. I found the -12dB that these transformers attenuate helpful. At full volume the signal is quite loud but listenable. This works out to about 50W into my speakers.

I am using a volumite for the volume control. Prior to this setup I have used both Legato 3.1 and IVY. I thought these were very good, particularly Legato SE, but there was a little grain at lower volumes, where I listen quite often. The transformer eliminates this and has a nice smooth sound at low volumes. I think this might be attributed to the high common mode noise rejection of the transformers, plus with the attenuation the DAC is outputting more signal.

I am quite happy with this combo. Although I still plan to do some more experimenting...

Originally Posted by Russ White

Lowering the gain of the previous two output stages will likely yield similar (or maybe better) results.

I haven't yet reported back, but I did try Russ' suggestion. I modified the Legato balanced stage with ZFoil resistors, and the opamp stage with Dale PTF film resistors. The new output level of Legato is 600 mV FS. Sounds great! Unfortunately, now that it's burnt in I can't do a very good comparison from memory, and an AB comparison is difficult. Regardless though, it sounds so good I don't think I will switch back again anytime soon.

I know this is a little off topic, but I thought I should let you know I switched back from transformers and am quite happy.

[Russ White]

Originally Posted by reactivepower

I haven't yet reported back, but I did try Russ' suggestion. I modified the Legato balanced stage with ZFoil resistors, and the opamp stage with Dale PTF film resistors. The new output level of Legato is 600 mV FS. Sounds great! Unfortunately, now that it's burnt in I can't do a very good comparison from memory, and an AB comparison is difficult. Regardless though, it sounds so good I don't think I will switch back again anytime soon.

I know this is a little off topic, but I thought I should let you know I switched back from transformers and am quite happy.

That's all that matter's. I bet it does sound great.

[Joe Rasmussen]

Originally Posted by chi0001

anyone can help me?
i have a output transformer, and i want to connect it to buffalo 3 dac o/p, here is the pic, which no.1,2,3 is correct?

How does "1" work. Or am I missing anything?

"3" will give you the full output of the DAC, assuming transformer is 1:1 ?

"2" will give somewhat reduced output, but give a fuller and more pleasing sound. I would ground the resistors, and even experiment with values.

Up to you, see what you like best.

Cheers, Joe R.

[luigilamarca]

hi, i have one question,
I have the buffalo dac 3 and would like to connect it direcly in my preamplifier,
My preamplifier is audio tekne push pull circuit with transformer 30k-30k
in cd imput.

i know that the buffalo dac is 781 ohm
I ask you the matching impedence is realizzated ?
the dc osfet it can a problem ?

thanks for the Help....

[audiodesign]

Joe see this:

DAC-END R (ES9018)

[Joe Rasmussen]

Originally Posted by audiodesign

Joe see this:

DAC-END R (ES9018)

Oh, that was you? OK, no worries.

Cheers, Joe R.