P R E A M P S for DAC4800A and Cherry

Big Red Machine · « **Reply #20 on:** 16 Apr 2010, 01:12 am »

Quote from: Big Red Machine on 12 Apr 2010, 07:31 pm

So let me try this again. Say we had a computer, into the SS Db Labs dac, then a Dodd tube buffer, and then a 4800A or Cherry Jr., and then 87 db 4 ohm speakers.

Would the input and output impedances, gains, flavors, etc. allow the Dodd to actually control the volume???

Tommy, do you think this combo would work?

watercourse · « **Reply #21 on:** 16 Apr 2010, 02:49 pm »

I haven't had direct experience with the Dodd buffer - which has 0 gain - but with the battery pre at 16db gain (per specs at Underwood Hifi), I usually have the Dodd's volume set between 9 o'clock for normal listening, and never above 12 o'clock from my Bel Canto DAC3 (used as a source), which has max output of 2.25Vrms via RCA. Well, maybe once in a while above 12 o'clock, but never when the wife is home

With my lower output phono stage, I still never push above ~ 12 o'clock.
My intuition is that I rarely actually need the gain with the Cherry Jr.'s 27.4 db gain driving my speakers that are 91db efficient.
The Dodd buffer has a lower impedance (130) than the pre (<200), so the buffer should theoretically be a better match for the 4800A/Cherry Jr.
Why don't you give Gary Dodd a holler? Or maybe Tommy can weigh in now that he knows a bit more from my system characteristics?
Speaking of output impedance and other matters, my experience with unbalanced vs. balanced pre's mirrors Tommy's - with similar output impedances, the balanced pre is quieter with the Cherry. But in my case, the tube sound is preferred.

Bill Baker · « **Reply #22 on:** 16 Apr 2010, 07:59 pm »

Quote

the balanced pre is quieter with the Cherry

Most of this will be due to the design of the preamp rather than balanced vs unbalanced. My Purity One that was driving the DAC amps was unbalanced with an output impedance of 800 ohms and mated very well with the amps. (The balanced pieces' outputs are 180 ohm).

As far as volume setting goes, it depends on what setting the preamp was on. With multiple attenuation settings, I can have gain of 22dB, 16dB or 12dB on the Purity. At full gain, 22dB, I did not have as much travel on the volume knob but still dead quiet. I prefered the 16dB setting on the Purity as well as the 13dB setting on the Basis preamp that I also used with the amp. The Basis can be configured for 23dB, 17dB or 13dB with an output impedance of 1.7K ohms.

Average output voltage from sources used was 1.7V-2V.

Unfortunately I do not have any one else's preamps around any longer for comparison with the DAC amp.

For what it's worth, the speakers I was using with the amp are 93dB with multiple plannar tweeters working from 600Hz on up so if any noise was there, it would have been easily noticed. It proved that these amps can be as quiet as midnight.

We are working on bringing this amp back in

AmpDesigner333 · « **Reply #23 on:** 25 Apr 2010, 02:52 pm »

Quote from: Response Audio on 16 Apr 2010, 07:59 pm

Most of this will be due to the design of the preamp rather than balanced vs unbalanced. My Purity One that was driving the DAC amps was unbalanced with an output impedance of 800 ohms and mated very well with the amps. (The balanced pieces' outputs are 180 ohm).

As far as volume setting goes, it depends on what setting the preamp was on. With multiple attenuation settings, I can have gain of 22dB, 16dB or 12dB on the Purity. At full gain, 22dB, I did not have as much travel on the volume knob but still dead quiet. I prefered the 16dB setting on the Purity as well as the 13dB setting on the Basis preamp that I also used with the amp. The Basis can be configured for 23dB, 17dB or 13dB with an output impedance of 1.7K ohms.

Average output voltage from sources used was 1.7V-2V.

Unfortunately I do not have any one else's preamps around any longer for comparison with the DAC amp.

For what it's worth, the speakers I was using with the amp are 93dB with multiple plannar tweeters working from 600Hz on up so if any noise was there, it would have been easily noticed. It proved that these amps can be as quiet as midnight.

We are working on bringing this amp back in

Bill,
When you say "Average output voltage from sources used was 1.7V-2V.", do you mean full scale from the source driving the preamp? Thanks.
-Tommy

AmpDesigner333 · « **Reply #24 on:** 28 Apr 2010, 04:06 am »

Quote from: Big Red Machine on 16 Apr 2010, 01:12 am

Tommy, do you think this combo would work?

Yes, but if I've been looking at the right information, the only volume control is the PC scaling the data before it enters the D/A. I'd be worried about clicks/pops associated with PC audio since you can't lower the volume to be safe when switching sources, etc. There's also the accidental volume WAY HIGH problem and the time it takes to lower it on the PC before you hurt your ears (or speakers). The Cherry puts out a LOT of power and it's better to have a preamp or D/A with a volume control. Maybe someone can comment on the volume "safety" issue with the dB Audio Labs D/A...

Big Red Machine · « **Reply #25 on:** 28 Apr 2010, 12:24 pm »

Quote from: AmpDesigner333 on 28 Apr 2010, 04:06 am

Yes, but if I've been looking at the right information, the only volume control is the PC scaling the data before it enters the D/A. I'd be worried about clicks/pops associated with PC audio since you can't lower the volume to be safe when switching sources, etc. There's also the accidental volume WAY HIGH problem and the time it takes to lower it on the PC before you hurt your ears (or speakers). The Cherry puts out a LOT of power and it's better to have a preamp or D/A with a volume control. Maybe someone can comment on the volume "safety" issue with the dB Audio Labs D/A...

The Dodd buffer, with no gain, would be the volume control. It's the no gain parameter that has me concerned.

Barry_NJ · « **Reply #26 on:** 28 Apr 2010, 07:32 pm »

Quote from: Big Red Machine on 28 Apr 2010, 12:24 pm

The Dodd buffer, with no gain, would be the volume control. It's the no gain parameter that has me concerned.

Hmmm... I very, very, rarely listen at 0 dB, never mind above that. I usually listen at around -15dB.

Big Red Machine · « **Reply #27 on:** 28 Apr 2010, 07:44 pm »

Throttling it back from 0 db is fine with me. But will it NEED to be throttled back is what I am trying to ascertain. I'd hate to wind up with the opposite effect (need gain, but can't get it w/o a gain stage in the pre).

ebag4 · « **Reply #28 on:** 28 Apr 2010, 08:19 pm »

Hey BRM,
If you are running Foobar or another program with volume control built in you might simply connect your DAC to the amp and see if more gain is needed, if not the Dodd Buffer would work for you. I am listening to my DIY Dodd Buffer right now and it is sounding mighty fine!

Best,
Ed

AmpDesigner333 · « **Reply #29 on:** 28 Apr 2010, 09:42 pm »

Quote from: Big Red Machine on 28 Apr 2010, 07:44 pm

Throttling it back from 0 db is fine with me. But will it NEED to be throttled back is what I am trying to ascertain. I'd hate to wind up with the opposite effect (need gain, but can't get it w/o a gain stage in the pre).

The Dodd web site info here doesn't specify a volume control in the text:
http://doddaudio.com/BatteryPoweredTubeBufferPreamp.aspx

However, the picture shows a volume control. Oops, didn't see that at first. There's no picture of the back, so I assume the output is single ended only (no XLRs).

The Tranquility D/A puts out more than 2.0V full scale, shown here:
http://www.dbaudiolabs.com/
(look at the Tranquility Specs page)

At 2.1V, the Cherry Amp delivers 300W into 8 ohms. This may be fine as long as the source is not on the low side. It will take some use to determine if the end-to-end gain is enough, and it will depend on the music and tastes of the listener.

So it's worth a try, but you might be better off going directly to the amp or through something that has a balanced output (XLRs). Going directly to the amp from the D/A will depend on the behavior of the D/A and PC software.

Take a look at the preamps mentioned here to see what other Cherry Amp users are saying, and please post there too:
http://www.audiocircle.com/index.php?topic=79614.msg758665#msg758665

Big Red Machine · « **Reply #30 on:** 28 Apr 2010, 10:04 pm »

Yep, been looking at the list and my pocketbook and Audiogon for something tubed and balanced as a primary choice.

Bill Baker · « **Reply #31 on:** 29 Apr 2010, 03:07 am »

Quote

Bill,
When you say "Average output voltage from sources used was 1.7V-2V.", do you mean full scale from the source driving the preamp?

The voltage is the output from the source (CD player, DAC, etc) with some being quite a bit ower. There were fed into the preamp which I was running at 16dB output gain.

I did run it for a short period directly from my DAC, Audio Note Custom DAC 2.1 Deluxe, but I did not get the same sense of spaciousness, without the preamp.

ooheadsoo · « **Reply #32 on:** 29 Apr 2010, 03:39 am »

I'm using a solid state:

Nuforce P8 with balanced outputs

Clean, clear, crisp.

AmpDesigner333 · « **Reply #33 on:** 29 Apr 2010, 10:44 pm »

This link will get you to the list quicker:
http://www.audiocircle.com/index.php?topic=78819.msg748487#msg748487

At some point, I'd like to compile all the customer responses on this topic.

Thanks again for the great posts...

AmpDesigner333 · « **Reply #34 on:** 29 Apr 2010, 11:05 pm »

BRM looking for a preamp to go with Cherry:
http://www.audiocircle.com/index.php?topic=80439.new;topicseen#new

AmpDesigner333 · « **Reply #35 on:** 13 Jun 2010, 06:41 am »

Is anyone here familiar with the "Matrix Mini-I"?
http://www.head-fi.org/forum/thread/441960/matrix-mini-i-balanced-dac-hp-amp

AmpDesigner333 · « **Reply #36 on:** 13 Jun 2010, 03:05 pm »

Quote from: AmpDesigner333 on 13 Jun 2010, 06:41 am

Is anyone here familiar with the "Matrix Mini-I"?
http://www.head-fi.org/forum/thread/441960/matrix-mini-i-balanced-dac-hp-amp

Here's more info:
http://www.pacificvalve.us/MatrixBalanced.html

It's $373 from Pacific Valve, but it says "out of stock" on their site. It has balanced outputs and an output level control --- to skip the preamp.

Please let me know if you've heard of this D/A product. Thanks again.

targa · « **Reply #37 on:** 14 Jun 2010, 01:49 pm »

i use a balanced version of Placette Audio Passive Preamp: RVC. this works great with the Jerry Jr. i also use a balanced version of the passive preamp made by Luminous Audio Axiom in my second system (HP laptop > USB converter > Stello DA220 > Luminous Audio Axiom > Dynaudio BM5a active speakers).

at one time, I put the Axiom in my main system (HP laptop > USB converter > EMM Labs DAC6e > D.A.C. Jerry Jr > SP Tech Timepiece 3.0) replacing the Placette. I wanted to test how good the Axiom is… well, the Axiom falls far behind the Placette. Axiom is more grainy, noisy and lacks details of the Placette. Big difference.

mojave · « **Reply #38 on:** 14 Jun 2010, 02:06 pm »

Quote from: targa on 14 Jun 2010, 01:49 pm

i use a balanced version of Placette Audio Passive Preamp: RVC. this works great with the Jerry Jr. i also use a balanced version of the passive preamp made by Luminous Audio Axiom in my second system (HP laptop > USB converter > Stello DA220 > Luminous Audio Axiom > Dynaudio BM5a active speakers).

at one time, I put the Axiom in my main system (HP laptop > USB converter > EMM Labs DAC6e > D.A.C. Jerry Jr > SP Tech Timepiece 3.0) replacing the Placette. I wanted to test how good the Axiom is… well, the Axiom falls far behind the Placette. Axiom is more grainy, noisy and lacks details of the Placette. Big difference.

I thought you had the Cherry Jr, not a Jerry Jr.

targa · « **Reply #39 on:** 17 Jun 2010, 03:21 am »

true and thank you for the correction... my mind was not in the right place.