Attenuators

MPW

MPW

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Aug 3, 2017
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Sacramento, CA
I own a Pass X350.8 that is being fed by a Cary SLP-05 using balanced inputs and outputs. In this configuration, the gain from the Cary is 24 dB. I find that I rarely move the preamp volume past about 8:00 and can get 90+ dB peaks at the listening position at this volume level. As I lower the volume, things can get a little squirrelly. Bottom line is I would like to lower the gain of the preamp going into the Pass. The system sounds great at high volumes, not so good at low volumes and I think there should be some advantage by raising the volume control on the preamp from that low position. I was looking at Rothwell attenuators, but I am not sure what that will do to the sonics. Would love any thoughts you guys have on the matter.
 
I have not used the Markertech attenuators, however, I have used the 12db Rothwell ones with a Cary SLP-05. I could barely turn it up to 9 o'clock as it would get too loud without the Rothwell's installed . I thought they took away a bit of detail but, as you know, sometimes it's really hard to tell. Good luck.
 
Speedskater said:
attenuators don't take away the detail, they reduce the background noise. It's about system 'Gain Structure' in getting each stage at it's optimum level.
Click to expand...

Agree it helps to optimize gain drive , but the added RLC change with IC and connectors will change tone and details, if matched correctly gains can be posit, sometimes not ..




Regards
 
MPW said:
I own a Pass X350.8 that is being fed by a Cary SLP-05 using balanced inputs and outputs. In this configuration, the gain from the Cary is 24 dB. I find that I rarely move the preamp volume past about 8:00 and can get 90+ dB peaks at the listening position at this volume level. As I lower the volume, things can get a little squirrelly. Bottom line is I would like to lower the gain of the preamp going into the Pass. The system sounds great at high volumes, not so good at low volumes and I think there should be some advantage by raising the volume control on the preamp from that low position. I was looking at Rothwell attenuators, but I am not sure what that will do to the sonics. Would love any thoughts you guys have on the matter.
Click to expand...

I would lower the drive into the Pre amp not the Amp ...!
 
The Cary SLP-05's line stage gain drops from 24db balanced to 17db when going single ended, this might be your answer. It might also sound better particularly since the Cary--and probably the Pass as well--don't use 'fully' balanced circuits from input to output and employ additional circuitry to invert the signal for balanced operation which gets bypassed when you go SE.
 
puroagave said:
The Cary SLP-05's line stage gain drops from 24db balanced to 17db when going single ended, this might be your answer. It might also sound better particularly since the Cary--and probably the Pass as well--don't use 'fully' balanced circuits from input to output and employ additional circuitry to invert the signal for balanced operation which gets bypassed when you go SE.
Click to expand...

I have used this setup in a fully single ended configuration with great success. When I moved to Pass amps, I tried balanced again and there was no going back. Much improved sonics. Kent English at Pass Labs confirmed for me that the Cary and Pass combination is best as balanced. I had always found the reverse to be true with other amps, but not with the Pass. I have recently began experimenting with the balanced inputs to the Cary. I had tried this configuration in the past (prior to the Ultimate Upgrade on the Cary) and always preferred single ended. I recently tried it again and am preferring the balanced inputs which put another set of tubes in the signal path. This is when I have run into the gain issue as you have indicated. I think I am going to get a set of balanced attenuators (likely Rothwell) which I can experiment with on the amp input vs the preamp input to see which is best and if this is even a viable option. Investment isn’t that high to conduct the experiment.
 
Wow 8M ..!!

The additional db gain says balanced input structure IMO, many balanced designs are not full differential but still run a “balanced” gain structure at input for noise control. Balanced claims are now becoming like “ Full class A “claims all marketing play along gibberish really, their is no such device I’m aware of currently that is full class A ...



Regards
 
MPW said:
Also, I have an 8 meter run from pre to amp which makes single ended problematic.
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Or around 26 ft which ive done before going SE from a CJ tube preamp to a Krell SS amp with no issues. The SLP05 has an output impedance of 400 ohm which is great in your case, as long your ICs are low in capacitance you wouldn't have bass issues but if you have ground loop issues then going SE will exacerbate them.
 
MPW said:
I have used this setup in a fully single ended configuration with great success. When I moved to Pass amps, I tried balanced again and there was no going back. Much improved sonics. Kent English at Pass Labs confirmed for me that the Cary and Pass combination is best as balanced. I had always found the reverse to be true with other amps, but not with the Pass. I have recently began experimenting with the balanced inputs to the Cary. I had tried this configuration in the past (prior to the Ultimate Upgrade on the Cary) and always preferred single ended. I recently tried it again and am preferring the balanced inputs which put another set of tubes in the signal path. This is when I have run into the gain issue as you have indicated. I think I am going to get a set of balanced attenuators (likely Rothwell) which I can experiment with on the amp input vs the preamp input to see which is best and if this is even a viable option. Investment isn’t that high to conduct the experiment.
Click to expand...

Let us know how the Rothwell works out. The elephant in the room still remains, the Cary has too much line stage gain. I've owned several ol skool tube preamps when 24db of line stage gain was de rigueur to make up for the low-ish gain of their internal phono stages. With separate phono stages being more common today the utility of 24db line stages has all but disappeared.
 
Pass recommended trying attenuators in the -10 to 12 dB range. Cary said they have a mod to reduce gain by 6 dB. I have the -10 dB Rothwell’s on order and will report back my impressions after they arrive. Coming from England, so it will be a few weeks.
 
Anything inserted in the signal path has the opportunity to degrade sonics.
 
@MPW sorry for being late to the thread. I have an extra pair of Rothwell XLR attenuators I can give you. My system has changed so I don’t need them anymore. Happy to help the Shark community. If you PM me your address I’ll ship them to you (from NY)
 
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