2. amps-preamps
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Different gain on 2 amps.

I never posted before. OK, here's the deal. I have a new VAC preamp that has no tape monitor output. Only outputs are after the volume control. I want to feed the output of the preamp into 2 separate amplifiers. One to feed my listening room speakers, and the other to feed a second power amp to drive some nice MB Quart speakers in my kitchen. I have done this before using the tape monitor out to a second preamp, then to the second amp and on to the kitchen. Separate volume controls, no sweat. 
Now I have a very nice VAC Phi 200 tube power amp for the listening room. Gain is 37 DB for Single  ended RCA's. The other amp for the kitchen is a solid state CJ amp with a gain of 27. So I connected these 2 amps to the 2 outputs from the VAC preamp. Everything works, except the volume in the listening room is way louder due to the difference in gain of the 2 amps.   As we all know, putting the signal into another preamp is no help.
2 questions:

1. Any ideas on how I can boost up the preamp output from the VAC preamp to the CJ power amp so as to equalize the volumes in both rooms? 

2. Anyone know a reasonably priced amp with a gain of 37 or close to that?  
BTW, I don't/can't just buy another VAC tube amp for the kitchen. Way too big, way too expensive. 
otto1234
almarg's avatar
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almarg
9,670 posts
 
Yes, consistent with Alan’s suggestion consider putting a pair of Rothwell 10 db attenuators at the inputs of the Phi 200. More than a few members here have used them, with some (including me) having found them to be very transparent, although some others have reported them to result in compromised dynamics or other sonic issues.

My suspicion is that a reason for the discrepancies in these reports is differences in the input impedances of the components with which they are used. While the input impedance of the Phi 200 doesn’t appear to be specified, I suspect that it is high, which figures to increase the likelihood of success with passive attenuators such as these.

Regards,
-- Al

georgehifi's avatar
georgehifi
10,312 posts
 
@otto1234

Just use a Shiit Sys for $49 on the input of the highest gain amp. That way you can balance them both perfectly to your own ear.

http://schiit.com/products/sys

Cheers George
erik_squires
16,398 posts
 
The issue is more than gain of the amps, but also sensitivity of the speakers. :)

In typical audiophile fashion, you should get less sensitive speakers for your listening room. :D :D :D

One thing to watch out for though is tube preamps don't like to split their output. You could be doing your listening room a disservice by trying this.

Best,

Erik
otto1234 OP
3 posts
 
Thanks everybody.  I was hoping that could do something to the signal going to the lesser amp rather than messing with what is going to the  VAC Phi 200.  I saw a device at Amazon called an iBoost 800.  Wondering if anybody has seen/used one of these?

https://www.amazon.com/iBoost-800-Stereo-Amplifier-Booster/dp/B00CVDN2O0/ref=sr_1_1?ie=UTF8&qid=...

The diagram shown on the Amazon website shows it used to boost the signal for a very long run of cable.  Also, the comments show that some people use it to boost signal to a subwoofer.  These devices are pretty cheap and I will probably try the Shiit Sys and the iBoost. 
erik_squires
16,398 posts
 
So I read up on your VAC amp. The gain is LESS via XLR, so if you can swap cables, you can reduce the output somewhat.

Best,

Erik

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