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Connecting CD directly to Poweramp

I have an Ah! Tjoeb 99 and recently decided to plug it straight into my (decent) poweramp (audiolab 8000p) and bypass my (mediocre) preamp (NAD 118). This limits me to using the volume control on the CD player. However, the voltage output on the CD is too high for the amp, so I have to turn the volume way down in order to use it. Since it is a digital volume control I am losing a lot of information doing it this way. But the character of the sound is much better, since I am hearing the tube sound of the CD player much more.

I am told that I have two choices (assuming I don't want to spend 2000 bucks on a decent preamp): buy a passive attenuator (e.g. Creek OBH 12) or adjust the voltage output on the CD player (allowing me to set the CD volume at a higher level and so preserve information that currently I am losing).

Can anyone tell me what the pros and cons of these two approaches are? I am worried that using a "passive" unit in the signal path will take away some of that tube sound, but at the same time I don't know what decreasing the voltage output will do, since it is set at the "optimal" level at the factory. On the other hand, with a passive unit I can plug two inputs into it, which gives me more flexibility in the system.

Any ideas, comments?
andrewa
8 responses Add your response
ipy
113 posts
 
I have been using the Audio Synthesis Passion Pre (Passive) for a number of years with great success in my system. When you properly match the Passion with the rest of your system taking care of it's compatibity factor with your interconnects (preferably short & low capacitance) and power amp (input sensitivity of 0.5V and impedance of 440kohms will be perfect), it will sound magic. I do find in most cases the compatibity issue has not been an "issue". I have used Pass Lab Aleph 3 (SS 30 watt), Ayre V3 (SS 100 watt) & Audion Golden Nights (tubed 300B) with no problems. My speakers are rated with sensitivity of only 84dB/m but I do not have a huge music room though, only 15.6 x 10.5 x 8.
Good luck.............
eldartford
4,262 posts
 
All you need is a couple of resistors at the power amp input to attenuate the gain. (You could probaby just change one resistor in the amp).

By the way, a "digital" volume control does not necessarily loose information. There is a resistor ladder network (analog attenuator) the setting of which is digitally selected.
rkeman
66 posts
 
Try an Monolithic PA-1 or one of the Goldpoint passive preamps (www.goldpoint.com). You will love either.
mijknarf
266 posts
 
I agree with Listener57. I have had a pair of EVS attenuators on my amp for a single source (cdp) for several months and I am thrilled with the performance. Very well made, Ric is a super guy who will take the time to talk to you about what may be best for your system. Good luck!
gordus
118 posts
 
Channel Islands is another maker of excellent and inexpensive passives
listener57
730 posts
 
You might want to contact tweakaudio.com which is home to the $350 retail price Ultimate Attenuators which attach directly onto the amp input RCA terminals making a separate interconnect unnecessary. Avoiding another interconnect reduces the cost of adding this minimalist equivalent to a passive preamp. The designer, Ric, has different models for tube or transistor amp. This will optimize your performance if you do not need remote control, and listen exclusively to one source, CD's in your example. I have been a fan of this approach after hearing excellent improvement over any moderate price conventional active preamp.
jdombrow
371 posts
 
Depending on your budget, you might consider a transformer volume control (TVC). Bent Audio makes an outstanding unit.

jd
elevick
2,636 posts
 
If I'm correct, the Tjoeb is based on the Marantz CD. The volume control stinks but the sound is nice. I wouldn't bother modifying the unit for a lower voltage. The volume is still very cheaply done and won't allow for "infinite" control-simply too few steps.

A Creek will do the job beatifully. However, there is a major problem with the remote on a creek. It is affected by the signals from the cd player. Every time you push up, down, ff or rw on the cd, it will adjust the volume on the creek!

You can always find another passive volume control or for similar money, buy an older high end pre-amp (SUMO or similar).
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