"Too much gain"? (Cary SLP05 question)

@khloebo , although you addressed this to  @avanti1960 

 I should go back and see if the rectifier tube actually does anything for me. 

I have rolled three 5AR4s (the original Sovtek, a GL, and a Mullard with Amperex brand on it) and I cannot say that anything reached out and slapped me on the face.  But with that typed, I do not possess golden ears and there may have been a difference that was subliminal, meaning the way I believe  my ear/brain connection works is that I may be enjoying something either more or actually less, but it is a subconcious type of thing that results in either pleasure or displeasure.  If that makes sense, because it is a concept that is hard for  me to put into words.  And it makes A/Bs hard to do for me.  

I also have a couple of 5AR4s that I picked up that I have yet to try yet--an actual Dutch Amperex and a Japanese tube . . . maybe a Nakamichi?  I’d have to go back and fid it and look at it.  Someone on ebay was once selling some 5AR4s that they were saying were the "Japanese Mullards" (which I had heard of before) and the way I was doing ebay binges,at the time, I am surprised now that I didn’t buy one of those also.

A PS on edit:  hogging out those holes for the upgrade pots makes be a tad nervous, I will have to think about that.  I may try to get back to you on this project.

Please note that Cary’s preamp gain is done BEFORE it reaches either the trim or main volume control.  The only thing that trim pots and the main volume control do is attenuate the signal.  The volume controls will not alter the noise floor as it has already passed through the gain stage. However, as one poster has pointed out, cheap volume pots have the ability to act as a filter.  
 

If Cary really wanted to offer an Ultimate Upgrade, they should address the volume pots which is the SLP 05 Achilles heal. 

@immatthewj  Good advice on the 5AR4s.  As long as the power rectifier circuit was well designed any change of tube should have a minimal effect.  At that point it should be noted that variations in tube production over the years might also have just as significant an effect, positive or negative.  My Sovtek had ~6000+ hours on it, figured getting a Mullard to try couldn't hurt. I will likely buy a backup 5AR4 from new production, unless the Mullard clearly shows it is better.

Yeah, the holes are a bit of an issue.  If I did it again I would get a step bit or reamer and practice on some scrap first to make sure it remains perfectly circular and centered.  I suppose I could have made a jig to get it on the drill press without total disassembly too.  Meh.  I had to do some hand filing in the end to get it where I wanted.  The soldering is super easy, and if you remove the mounts temporarily on the headphone stage there is enough room to do all the work.

@testpilot I totally agree.  The honeywell trim pots are a couple dollars each and are made for ATV controls, among other gross implementations.  The Alps you could buy for under $25 with the remote motor.  There is a ton of room inside the case for upgrades.  It should be an option to go stepped or switched relay.

Glad I woke this thread up again.

@avanti1960 appreciate your and others’ input. 

Please let me know if I have my interpretation of the gain issue right. I do intend to use balanced outs as this is my standard with all the pres and amps I’ve used, plus I’m hearing the Cary balanced outs have better soundstage, etc.

On my most recent pres, the gain is 12db on an ARC, and 20db on a Rogue. The SLP is 24db. My current amp is a newer Bryston cubed with selectable gain of 23 or 29db.

The SLP gain is high. By reducing the gain on the two pots this can be addressed. However, the quality of these pots is low, and they add some noise or other undesirable affect to the sound.

By virtue of the high gain, I’m assuming the volume will be set relatively low when the 2 gain pots are full on. This to me seems like the volume adjustment will be difficult, as even small adjustments will result in big changes. Yet, if I adjust the gain down, noise is introduced. I do prefer to have somewhat normal use of the volume.

My main questions are this.

When the gain pots are adjusted down, is the noise or otherwise negative effect noticeable?

With the Bryston’s gain set to 23db, should I have normal use of the volume with the gain pots full on?

It’s also been said that with the upgrade, the SLP’s gain is somewhat reduced.

What else should I be concerned about?

It almost seems that users of this pre have to go through all sorts of accommodations to get this thing to work normally. But the great reviews and comments from some users on the sound quality are keeping me interested.

The other pre I’m considering is the Aric Motherlode XL. I’m not seeing any controversy over that pre at all. However, there are features of the Cary I really like. The remote with more functions, attractive case work, and the fact that Cary is offering me 20% off the price after I emailed them a few questions. Plus the Cary is available in a short time, while it’s a 6 month wait for the Aric.

Aric has been very helpful in our emails and I feel he would be a great guy to deal with if I were to own one of his units. The communications from Cary have been somewhat different.

My system is fairly resolving. Speakers are Focal Sopras.

Look forward to any help with this and thanks in advance.

I have received the message below verbatim from Cary today when inquiring about the upgrade gain, the pots, and any difference between balanced and RCA sound quality. Note an earlier post on this thread said the pots were "cheap Honeywell pots". 

The gain is reduced by 6db for both XLR and RCA.

The volume pot is an Alps motorized pot custom made for us by Alps in Japan. The balance pots are made by Bourns. Both brands are highly regarded and make excellent components. These are not inexpensive components.

I think differences in sound quality between RCA and balanced could result from several factors – cables, length of cable runs, etc.  Inherently, I think both are excellent

The SLP-05 is one of the most highly regarded preamps on the market. It has been around for many years. This doesn’t happen by accident