Boy, I really loved reading that post Distortions. |
I ended up purchasing the ARC SD135 amplifier that was for sale here. I received it today via UPS. I installed it in my system after work, and I have been listening to it these last few hours. The first thing I noticed when I cued up a 1970s UK pressing of Yes' 'Fragile' LP was that I needed to turn the volume up to 12:00 compared to 9:00 with my DNA-125. The second thing I noticed was how much more fleshed out everything sounded compared to the DNA-125. Bass notes were more pronounced and imaging was much more lush, now being three dimensional. The DNA-125 was "almost there," while with the SD135, I am there. Something is definitely to be said for brand synergy. It almost seems like Audio Research had users of their classic tube gear in mind when they designed the SD-135. While the DNA-125 is a brilliant amplifier, the ARC SD135 is another league altogether. I have not noticed such a huge improvement in the sound of my system since I started cleaning my records with a record cleaning machine instead of hand washing them.
My music sounds so wonderful that I cannot stop listening to it. In successive order I have played Pink Floyd's 'Dark Side of the Moon' SACD, an original UK LP pressing of Spring's self-titled album on RCA, the first side of an original UK LP pressing of ELP's 'Tarkus,' and I am now listening to an early UK LP pressing of John McLaughlin's 'Extrapolation' on Polydor. This is what enjoying music is all about. If the wife didn't want to go out to dinner tonight, I would almost be tempted to listen to every album in my progressive rock collection.
In case future web searchers view this thread years down the road, if you are lookiamplifier outstanding amplifier which has low gain to pair with your high gain tube preamp, look no further than the 130 watt/channel SD135. It is a real sleeper and an absolute gem in the ARC line-up.
One other great thing that didn't happen when I powered up the SD135 was the absence of the somewhat loud thump I would hear when I turned on the McCormack DNA-125. This occured even when I let my SP8 warm up for 20 minutes. I have been told that this was caused by DC voltage. The SD135 has a sophisticated, non-fused sensing circuit to protect it and your loudspeakers from DC at the output. The SD135 starts up slowly with a two second warm-up cycle. Hence there are no thumps. The SD135 is heartily recommended. |
Yes, an old trick with ARC preamps is to run CD into the tape monitor input, you get higher gain but more transparency.
For amplifiers the std is usually 26db, I had Rowland amplifiers that had adjustable gain internally from 20db to 32db, you might want to check those out. |
Yep, I think their preamps were designed with phono and tape in mind, esp. the SP10. I was told that the service tech removed a resistor on the bottom of the board, and they left it hanging so I can re-solder it if I should want full gain again. |
I bet ARC had to do lots of tweaking of their circuit to reduce the gain. Transparency loss is due to the excessive feedback they have to apply. Their preamps designed to be best with tape or analogue sources. |
I had ARC reduce the gain on my SP8 a couple months ago. I was told by the service manager that they do lots of gain reductions on SP8's and their other older preamps. ARC said that reducin gain might lead to a slight loss of transparency, but that it would not be noticeable. ARC also replaced all of the original caps with new Nichicons. One of the caps was indeed faulty. |
Bad idea since the preamp will not be stable. It's been designed for a specific feedback and increasing it to lower the gain may bring amp to oscillation. |
You may want to call Calvin at ARC. He might have some practical solutions. I mention in passing that the SP-8 is a bit dated. If you love your amp, may be you should switch out the pre. I am not suggesting that you get rid of the amp and keep the SP-8, but I am mentioning in passing that ARC gear works synergistically well together. If you love the SP-8, consider an ARC amp, even a used one. By the way, have you had ARC go over your SP-8 recently. Old gear oftentimes needs a freshening up, especially the caps. Something to think about. |
Hi Guys,
Thank you for your help. I am using a Marantz SA8001 for my source. I believe its analog output level is 2.3V RMS.
Marakanetz,
Why do you think lowering the gain of the SP8 is a bad idea? |
lowering gain of ARC is bad idea. |
Well, I really think the culprit is that SP-8. I'd be willing to forward some funds to help you pay for a new pre. :-) |
Since you have already made an attempt at lowering the gain of your SP-8 my guess is your source is where the real problem lies not the amp/preamp combination. If you are using a Theta with 7 volts output or some other digital source with high voltage that is what needs to be corrected. |
all you need is attenuation and no gain or maximum to +6db. look for the volume control db range which is far more important. |
Thank you for your help. Steve, I do really enjoy the DNA-125. It is a wonderful amplifier, and I can see why people often partner it with Vandersteen speakers.
Is anyone here familiar with the ARC SD135? According to Kalvin at ARC, it has about 16db of gain when used with single ended connectors. The SD-135 seems to be an obscure model as I cannot find much information about it. I do not think it was reviewed by any of the audiophile press. However, from the online posts I have read by its owners, the SD-135 seems to be a highly well-regarded amplifier. |
Personally I don't like AudioResearch preamps coz they have too much gain. McCormack or Wyred4Sound preamp will work much and much better again. Remember there's no preamp sounds good just by itself, but one matching your system. |
Honestly, Audio Research in my opinion has not produced a solid state amplifier that can compete with the McCormack's soundstaging & musicality except for the AR 100.2 which has been tauted as one of their best solid state amps. Their forte has mostly been in tube gear with some exceptions.
Right now I have the opposite problem you are experiencing. My active preamp is not providing enough gain for my current amp for the exception of the CD player & most always the CD player has more gain than the other source components. If you mostly listen to CDs it would nice if you could find a quality player with built-in level control to alleviate your problem. If push comes to shove I would prefer your situation. |
30dB of voltage gain is slightly higher than average, while an amp with around 24dB gain may be more typical - but the difference is only 6dB, and that won't buy you much additional range on your volume control (very little, in fact). The real issue is the volume control not resolving the low-end of the attenuation range well (combined with the high gain of the preamp), but there isn't much you can do about that. If you are going to change amps, try to find one closer to 20dB gain if possible, or at least try to maximize the gain difference.
Another option is to use a truly transparent signal attenuator designed for use in high-performance audio systems. By strange coincidence, I happen to be making just the thing ;-)
Best regards,
Steve McCormack
SMc Audio |
Have you considered just lowering the voltage delivered to your preamp from your sources by using Rothwell's audio attenuators? It's a lot cheaper than buying a new amp and their insertion in the audio chain is inaudible to my ears.
www.rothwellaudioproducts.co.uk/html/attenuators.html |
