Repair of the Peachtree Audio Pre-Amp with review first: PEACHTREE DECCO MSRP: $800 Review by Lorin Elias The Peachtree Audio Decco is a 50 watt per channel, hybrid tube integrated amplifier with an onboard digital to analog converter that can improve the sound of many digital sources. itunes or Windows Media, Squeezebox, Apple TV and Airport, Sonos, XM or Sirius tuners are just a few devices that work well with the Decco. The Decco, designed by well-known DAC guru Scott Nixon, has a USB input for your computer, a coax and optical input for any of the digital devices listed above. It also has two analog inputs for docking stations, CD players, tape decks or phono preamp. If you re a headphone lover, the Decco has a headphone section that mutes the speakers when headphones are plugged in. If you want to add a subwoofer or outboard amplifier, the Decco features a variable preamp-output. The Decco is designed to be an all-in-one solution for digital playback, though it does not contain a disk drive or transport of its own. Most Decco owners seem to be using this unit as a DAC/preamp combo. In fact, with the growth of the music server segment of the audiophile marketplace, there is a great need for components that effectively bridge multiple digital sources (music server, satellite radio, ipod/mp3 player, and CD/DVD/SACD player). The Decco's market timing could not be better. It is a veritable Swiss Army knife of a component, able to fill any number of roles. But does it really provide a Hi-Fi bridge between all these digital sources and a high-end music system? 1 P a g e
Specifications 50WPC at 8 ohm, 68WPC at 4ohms Tube (6922/6DJ8) pre-amp section 2 analog inputs 3 Digital inputs - USB, SPDIF, Coaxial Decodes MP3, MP4, FLAC, AFF, WAV Preamp Stereo output for additional amplifier or subwoofer Non-up sampling DAC Remote control volume and source selection +5dB, 55Hz bass EQ for small speakers Slot in back to accommodate Sonos ZP80 It certainly has the right list of features for the job. The "ins and outs" of the Decco are not quite what you would expect. There are two analog RCA inputs (Aux 1, Aux 2), three digital inputs (Coax, Optical, and USB), and one set of RCA pre-outs that are attenuated by the volume control. Nice pieces of audiophile kit with UBS inputs are still relatively rare, and this feature alone is enough to entice many shoppers who are looking for effective and economical means of extracting music from their computer systems. However we are still not done with the Decco's back panel. It also has a docking station for a Sonos ZP80 music player. I never tried this feature, as I primarily fed the Decco with the optical output from my SlimDevices (now Logitech) Squeezebox. 2 P a g e
Perhaps the biggest surprise on the panel is the +5dB, 55Hz bass EQ button, meant for use with small speakers. The yesteryear name for this button would have been "loudness". Finally, there are speaker outputs. These WBT-style binding posts for the speakers are excellent and accept any common speaker cable terminal. Overall, a busy back panel indeed. Unlike any other component I have encountered, most Decco users (at least those active in the audio forums) do not use the Decco to its full potential as an integrated amplifier at all. Instead, most users enjoy the Decco primarily as a DAC and preamp, saving the amplifier section for backup duty. I mostly used the pre-outs to drive a pair of monoblocks (Tube Audio Design Hibachi 125's). I also tried it as an integrated amplifier, and even tried subwoofers with it in a couple of configurations. When using the Decco as an integrated amplifier, this leaves the pre-outs free for driving a subwoofer. Of course, if you are using the preouts to drive another amplifier, this leaves the speaker binding posts on the Decco free to drive a passive subwoofer, or even an active one if the sub has high-level inputs. Given the relatively modest power output of the Decco (50 WPC into 8 ohms), I would not suggest using it to drive a passive subwoofer. However, I found it quite capable of driving an active subwoofer from either the RCA or speaker terminals. Before listening to a component, you usually have to look at it. I still have not made up my mind about the styling of the Decco. It sure is different from most Hi-Fi (not the standard sliver or flat black), and the white face is unlikely to match anything in your rack except for an older generation ipod or some Sonos components. The glossy black case looks great when it is perfectly clean, but the rest of the time, which is most of the time, the piano black finish is an extremely effective attractant for fingerprints and dust. The lines are elegant, and the tube window revealing a glowing triode reminds me of some of the Vincent or Kavent components with the same tube "bling". Also like the Vincent/Kavent gear, a little red LED actually provides much of the glow, not just the 6922 inside.the Decco is available in two additional colors, cherry and rosewood for and additional hundred bucks. 3 P a g e
Sonically, it is hard to find fault with the Decco's DAC and preamp. Female voices are absolutely sublime, full-bodied sonic images that float in front of the listener. Pieces like "Simple Love" by Alison Kraus leave the listener flinching; almost feeling Alison's breathe on one's face. The single dual-triode in the preamp section likely deserves credit for much of the body in female vocals through the Decco. When listening to more bass-demanding tracks, like "Let it go" by Great Big Sea, the Decco's articulate bass never bloats, unless of course you are running a full-range system with the "loudness" button engaged. If that is the case, your system is likely to start sounding like a Honda Civic stuffed full of subwoofers (minus the rattling body panels). The DAC does not up sample, and therefore it does not add any of the harshness or smear that up sampling can introduce. Some prefer the sound of up sampling, but I am not one of them. Although up sampled digital music is easier to listen to and does not lend itself to fatigue, I always wonder what I am missing. Not so with the Decco. The highs are crisp without being harsh, and the music has gobs of detail. The amplifier section of the Decco is not as strong as its front end. It almost seems unfair to criticize an $800 component for not being perfect at everything, but the quality of the amplifier is not quite on par with the rest of the unit. I tend to favor speakers with relatively low efficiency (less than 90dB), and cruel impedance curves, so it should not be a huge surprise that 50 WPC does not quite provide the level of grip and bass control that one would hope for. The problems don't end there though. In addition to the relatively modest power output, the chip amp fails to provide the same resolution and dynamics that can be achieved when using the Decco as a preamp alone. It still provides a very clean, open, spacious sound, but all the edges seem softer and less controlled. This is most obvious with bombastic orchestral music and hard-driving pop music, but when listening to smaller scale music (such as "Calling You" by Holly Cole); one would never miss the lack of power. 4 P a g e
The amplifier section does make some very pleasing, non-fatiguing sound, but it lacks the sparkle and drive that characterize the rest of the unit. It is fair to say though that more efficient speakers with more normal impedances would fare better. Used as a desktop system in an office or bedroom as it was mostly intended should meet the needs of most people. It is also fair to point out that most chip amps that put out 50 wpc would sell for much more than the Decco s total $800. A quick look at Scott Nixon s website reveals that he sells his NOS tube DAC alone (no amp or remote) for $595. That $799 looks pretty good, huh? The only other quibble I have with the Decco is its remote control. It leaves a lot to be desired. It is small, plastic, fussy and not a lesson in ergonomics. The largest button is marked "on", and it is located at the top of the unit. Pressing this button does...nothing. Well, not quite. If you turn the Decco on using the front panel, then turn it off using the "standby" button, and then the big "on" button will (sometimes) make the unit exit the standby condition. Why there is not a single "standby" button on the remote is a mystery to me. The buttons marked + and - adjust the volume, but only if you are perfectly level with the Decco, close to it (<6 feet?), and the moon is rising in Virgo. The source selection buttons allow switching between the three digital inputs and the two analog inputs. To my surprise, the "mute" button actually works. Even the color of the remote is non-matching in dull gray plastic. I have not figured out why, but I almost always hold this remote upside down at first. Something about the layout of the buttons seems to suggest that the big (placebo) "on" button should be on the bottom, and even after months of use, I have still not extinguished this bad habit. I wish I could find the designer for this device so I could confiscate all of their pencils. Perhaps Peachtree decided to put most of the money in the parts that make music. Again, for $800, one should not expect Krell cosmetics, but they might want to look into improving the range of the remote. This is truly a "Swiss Army knife" of a component. It is so versatile that it can find a useful role in almost any system. It is priced low enough and compact enough to be perfect for that second system in the bedroom/office/cottage, and yet the DAC and preamp perform well enough to be placed in a primary system with judicious selection of speakers. A college student would love one of these. I bought this one and would love to have another. 5 P a g e
The unit was shipped to me and was found to have shipping damage along with other cosmetic issues. Front clear face to tube was clouded from heat or something else not sure. Black chassis was broken on both top sides of the unit. This was the shipping damage from box even when packed correctly. 6 P a g e
This needs to be fixed for better look see of the main tube for the great sound as documented in the review. 7 P a g e
This was the worst part of the damage on the top of the chassis from shipping. 8 P a g e
Even the other side of the chassis took a hit. I hate those gorilla shipping guys. Customer did have insurance so I hope he can get at least a new chassis if not more for this $1K priced unit. 9 P a g e
First thing to fix is the tube see thru plate. 10 P a g e
ECC88 or 6992 or 6DJ8 all are the high MC type with 6.3volt heaters and 9 pin out design triode. 11 P a g e
One of the Triodes was with little to no MC so that would explain the customers complaint of not level output since Left and Right stereo is going thru this tube first as the pre-amp tube conditioner. Tube is going to be replacing with a 12AX7 for now since I do not have any ECC88 s at this time. 12 P a g e
Here is the outside of the box showing the huge hit it took from being thrown around. 13 P a g e
When first trying to get this to work on my laptop with Windows 10. 14 P a g e
At this point moving on since the unit can be checked with the analog inputs and customer informs me that he does not have any issues with the digital input of the unit. I on the other hand did but will return at the end of the report to try this one more time. 15 P a g e
Hand making a new front face see thru for the tube using a sheet of Lexan from Ace that was 10 bucks. It took me two cuts to get it right. 16 P a g e
When going back to the USB trouble shoot I will reference this DAC board with this IC. CS8414-CS CS8414 - CS, CSR, CSZ, CSZR this is Cirrus Logic DAC! EOL Too bad. EOL Date: 9/30/2009 Replacement Product: CS8416 - CSZ, CSZR Additional Note: The EOL date was changed by the Fab Manufacturer from 11/13/2009 to 09/30/2009. 17 P a g e
New tube with new glass! Nice! When doing functional test found one LED intermittent (Crap!) 18 P a g e
Touched up the LED so blue indicator worked for a while but then died. So had to pull the LED front panel board and replaced with same type but different color Green. Since customer uses the digital streaming input mainly I moved the green. So complete tear down of the front panel. Green was put on USB and other blue on the intermittent one channel mainly used by customer which is why it failed. The blues are running high current to be that bright and this one stayed on all the time. 19 P a g e
Audio check on outputs with loaded Boston HD5 s. 20 P a g e
Both channels looking great with 1K hear tracking well with input output phase and amplitude checked. Distortion very low with new tube. 20, 100, and 20K plus were all good! Great bandwidth performance with 12AX7. 20 Hz was very nice! 21 P a g e
No time to show that I checked all the frequencies and issues but all were done many times as repair of both cosmetic and the detailed checking out the design of the amp. I am designing a new pre-amp so this was good to do since there is no high voltage on the tube as seen later in the report. Sweep of generator. 22 P a g e
This is a comparison of the original tube and the tube I replaced it with: ECC88 changed to ECC83 ECC88 Specification and max ratings(*) Filament Voltage Filament Current Plate Voltage (max) Plate Current (max) Plate Dissipation (max) Screen Voltage (max) Screen Current (max) Screen Dissipation (max) 6.3 V 365 ma 130 V 25 ma 1.8 W --- V --- A --- W ECC83 Specification and max ratings(*) Filament Voltage Filament Current Plate Voltage (max) Plate Current (max) Plate Dissipation (max) Screen Voltage (max) Screen Current (max) Screen Dissipation (max) 6.3-12 V 300-150 ma 330 V 6 ma 1.1 W --- V --- A --- W While it's true that both the ECC88 and 12AX7 filaments will run on 6.3V, the pinouts are different. The ECC88 takes 6.3V between pins 4 & 5; the 12AX7 takes 12.6V between pins 4 & 5, or 6.3V between pins 9 and 4-5 [the latter linked together]. I did this for a test reason so that the tube will not fail for many years.but the customer is welcome to replace the tube back to an ECC88 if needed or does not like the sound. The performance is good on the bench as seen and the voltage is half for the heaters making for longer life along with ECC88 having other issues. See internet comments next. 23 P a g e
There is no definitive answer. From engineering point of view, the 2 tubes aren't swappable, ECC83 has a miu (amplification factor) of 100 while E88CC has a miu of 33, ECC83 has anode current of 1.2mA while E88CC has anode current of 15mA, ECC83 has transconductance of 1.6mA/V while E88CC has transconductance of 12.5mA/V. For 6.3V heater supply, with ECC83 it has to go 1 wire to pin 9 and 1 wire to pins 4 and 5 tied together, while with E88CC it has to go 1 wire to pin 4 and 1 wire to pin 5, while pin 9, which is shield, should connect to the ground. However, should you take care of the heaters connections, you can try and swap the tubes. It may work and sound okay and may not work well. The 12AX7 is great for noise and low distortion, but is bad at bandwidth, making it a poor choice if you want passive EQ. The 6922/6DJ8 has good bandwidth, but the design of the tube is not for audio: while very good linearity, the design is prone to excessive microphonics. IMO anything designed with them will exhibit a sonic signature that has a lot to do with microphonics. 12AT7s are also designed for audio and have less microphonics. They are also higher mu yet allow for wide bandwidth and so seem to me a good compromise of gain vs bandwidth vs coloration compared to the other two types, assuming that you want passive EQ. So in this case we see that the design of the circuit says a lot about what the tube choice is, for example if you are running feedback for the phono EQ the 12AX7 can do quite well. 24 P a g e
Back to chassis hardware.so ran silicon RTV down the broken chassis and held together overnight with clamps. 25 P a g e
Transformer had to come out first to get the board out for fixing the LED> 26 P a g e
The extra space made a great seat for the transformer while working on it! Special tools with a hard design to dis-assemble. 27 P a g e
Touched up and inspected the phenolic board but board was good. Part was not! 28 P a g e
The green LED was checked for brightness. Same package for front panel interface so great! 29 P a g e
Mag wired it in for a check. 30 P a g e
Looks good to me so the COAX was the most used I will put the USB into the COAX position. I plan to go back to the USB since I could not get it to work and that is bugging me.hope the customer likes it? 31 P a g e
12 AC for the 6VDC on the heater for the TUBE and possibly other power supply needs.cannot verify with no real schematic. 32 P a g e
Notice only 48VAC with center tap..so two reasons for no high voltage. 1: Safety requirements with creep ages and clearances. 2: Simple design and only one tube so both output semiconductors can use and still get the power. It s not what I would expect out of a well-designed pre but it works and has a good review. So no high voltage and phenolic boards are my two things I am not happy with so far. USB issue TBD. 33 P a g e
Pins were worn from all the miles like the LED needed some re-position and pinching but in this case did not replace the socket. This would be another huge tear down. 34 P a g e
Is this pin 9 Heater center tap need to verify that this is grounded or not if time permits maybe I can prove it out in theory? Clocking and pin number can be very confusing since are you looking at the drawing from the bottom or top? This drawing is from the bottom. I am doing this to double check my tube replacement since this has not been done before and many people would say it will not work. 35 P a g e
Pin 8 Cathode @ negative -23.9VDC this is without tube of course. 12AX7 pins 36 P a g e
Pin 7 is Grid number #1. Measuring only DC with no signal input and no tube so OK voltage. 12AX7 pin outs 37 P a g e
Pin 6 is Anode of Triode #1 sitting at positive +23.7VDC P 38 P a g e
This is pin #5 is heater positive @ 6.3VDC 39 P a g e
Meter is reading a little lower than ground so that means this is the ground pin 4. So 4 and 5 are getting the 6.3VDC across the with pin 9 left open otherwise the tube would be only hearing/working on one side only and would not work. Both channels sound great! 40 P a g e
Pin 3 is of course the Cathode for Triode #2 sitting at neg -23.9VDC 41 P a g e
Grid #2 ok with no input 42 P a g e
This is pin one Anode triode number #2 sitting @ positive +23.7VDC unloaded. 43 P a g e
The replaced tube ECC83 from the old ECC88 while putting my tester on 6.3VAC not 12.6VAC shows that it s not much lower around 250 lower MC and remember this is AC! The product has DC heaters for noise and DC will provide a little more true power to the heaters than AC. DC= RMS. So the tester is a little conservative. Thinking a 12AT7 would be nice to try but time is not on my side right now. 44 P a g e
Sorry for the long report but still have to check out the USB. I should have that DATA to go with the e- mail to the customer this afternoon when I try different computer interfaces and other possible tubes. Waiting on a phone call from a tube vendor here in the northwest for pickup. The unit is looking good with the chassis fixed as best/fast as possible. The tube window is now new as seen below. The green LED you can see below only on the USB function. All outputs and frequency bandwidth was check and found to be great on the bench. Its motor volume pot pretty cool and over all I really like the unit! I am going to try different tubes including the original and also the USB interface this afternoon if I have the time. The customer can elaborate on the sound he likes and the color of the different tubes if he wants to go down that road. Thanks, GT 45 P a g e