Hi, I am having some issues with either my cdp output level (6 vrms) or amp input sensitvity. Either way, I think I need to get an inline attenuator. I would prefer to get the very best attenuator available that does not degrade the signal in any way. I am absolutely new to this so I would appreciate any feedback. By the way, I need XLR and RCA.
You might want to get in touch with Marchand Electronics. They have a good selection and can tailor to your needs.
The XLR/RCA presents a difficulty because to be fully balanced means double the components. On the other hand, TVC's don't care about balanced or SE. Either way, you're essentially talking about a passive preamp, in some form.
The Pass amps have a low input impedance that can be difficult for passives but should be good using XLR.
If you go to www.goldpt.com you will find on page two very detailed explanations about the pros and cons of the resistor types series, ladder stepped and shunt attenuators.In my opinion the ladder stepped type[although more expensive would be the choice]you then get to choose the value and type of resistor also the make of switch.[Vishay and Shallco for me] You could always think about variable transformer tapped types also there are two basic types the auto transformer type such as the sonic euphoria and the switched output tap types like the silver rock and the bent audio there is a massive range of choices and all affect the sound.Among the nicest guys selling all choices of attenuators are Kevin Carter of K+K audio and John Chapman of Bent audio either of these guys will put you on the right track.
Herman, thanks for the reply. The issue I am having is that my volume is way too loud even at the next to the lowest possible volume setting. This is not the case with my current preamp but I have now auditioned two different (tube) preamps which both had this same extreme volume issue. The reason why I am looking for both RCA and XLR is becuase I am not sure what output connector my next preamp will have.
It occurs to me that all you need is resistors in male/female adaptors. How's your soldering? You might start with 3 KOhm and see if that works. To give you an idea of the rating, P=V^2/R, so 1 watt would be more than enough. If you can find Vishay at 1% tolerance, you're cookin'. You can't get more direct than that without cutting into the IC's.
RCA requires only one resistor on the positive (inner). XLR needs two. If I'm remembering correctly, (it's been a while) terminals 2 and 3 are hot while 1 is ground.
You dont need an active preamp, you are not using a Turntable so no need for phono or diferent sources switching, just CD direct to amps has enough gain. Sell your active preamp and go passive EVS like Tvad said use a low impedance of 1k will probably match better with your Pass amps with low input impedance. You can also try Placette RVC email or call Guy at Placette and ask about it, Both have 30 day money refund if you dont like it...they have smoked the best preamps out there given the right installation!
This is not the case with my current preamp but I have now auditioned two different (tube) preamps which both had this same extreme volume issue.
You can't just randomly insert componenets in your system, no matter how fine they may be in other systems, and expect them to work in yours. Any change you make has to be with the entire system in mind.
Those other 2 preamps are simply not compatible with your current system unless they have provisions for lowering their gain. I don't see the sense of introducing a preamp that has more gain than your system needs and then trying to compensate with attenuators. If you are set on the rest of your components then you just need to audition preamps that have the proper amount of gain for your "system."
Tonyptony - At first I did not think the Rothwell's colored the sound, but after hearing both the EVS and Endler attenuators to my ears and in my system I felt the Rothwell's were slightly warm. However, I have to say for the price, compared to the EVS and Endler attenuators, this slight coloration can easily be overlooked.
I think I figured out what is going on though I am not sure.
First, my cdp output is 6vrms which is much higher than the 2-3vrms that I usually see for other cdp.
Second, the max output of the pre I am auditioning is 50vrms while my current pre max output is 20vrms. They both have the same number of volume steps (0-100 at 0.5db each step). I think this tells me that for any given volume setting the preamp I am auditioning will be outputting a higher voltage than my current preamp. This would lead to higher volume. Both of the pres have about the same gain 17-20db.
Am I missing something?
Since my amps which seem to be have too low an input sensitivity (is too sensitive), are not going anywhere, it looks like I either find a pre that has lower output voltage and gain, or use an attenuator.
Tboooe, you need to re-read Herman's last post. Gain structure is the most fundamental element in system building (synergy). If the components you select are not compatible, then there is nothing you can do that will correctly "fix" the problem. In the context of a high end system an in-line attenuator between your main source and your premap just doesn't cut it.
Guy at Placette can make you some plug in attenuators with a single Vishay
Cyto, I'm not sure I see how this is possible, unless Guy uses the input impedance of the downstream component as the parallel element in the resistive divider. But I'm still not sure that will work. To get any kind of voltage drop introduced you'd need to insert a divider "circuit" - takes two resistors.
Tonyptony: Thanks for asking for clarification, I've had too much espresso today.
I had one of Guy's Excellent Placette Active Preamps but it was impedance mismatched with my high sensitivity Lamm M1.1 amps. He suggested either adding his dual control volumn or just simply plugging in some 10dB shunts he would build for me. It might have been two Vishay, but his point was that this would be a very clean way to address the issue without modding either component.
There is a reason I just listen to the stuff and don't design it.
Tboooe, gain is gain no matter what the maximum output is so that would not be the issue. Input voltage times gain = output voltage.
However, the stated gain is with the volume control all the way up. The taper of the volume control is usually not linear and may be different for the 2 preamps. For instance, one preamp with the volume control halfway up could be near full volume and the other one only at half volume.
Tony, an attenuator can indeed by made with a single resistor in series with the input. As you conjectured the input impedance of the amp is the other resistor in the divider.
Although I would prefer not using one if I dont have to, Im not as dead set against using an attenuator as some. After all, the volume control is simply an adjustable attenuator. In most cases I would use one at the input of the preamp though instead of the input to the amp. The signal from CD into pre is much hotter than from pre into amp, the input impedance of the pre is usually much higher than the input impedance of the amp, and Pass amps are among the lowest. If you find a pre you really like any competent tech should be able to pad the gain either at the input or at the volume control.
Excellent point Herman. There are pre-amps with input gain switches. The manufacturers saw nothing wrong with putting the reduction ahead of the pre-amp line stage. ARC did this and others I'm sure.
Actually, although no one has mentioned this (I didn't read all of the posts so maybe I just didn't see it), don't most amps have the attenuator between the source and the line stage and the signal thats being attenuated is the signal from the source to the pre-amp, not the pre-amp to the amp?
Thanks for asking for clarification, I've had too much espresso today
Not a problem. :) I may call him about this. I wonder if he builds the shunts in the same sort of RCA M-F assembly as Rothwell. I'm dying to find out where to get that kind of thing so I can try to build my own. I've asked here and on AA and no one seems to know. Checked the usual electronics parts websites, too.
In most cases I would use one at the input of the preamp though instead of the input to the amp
Yeah, I'd have to agree with that, Herman. Makes it more complicated for me, though. First I'd have to build or buy multiple pairs. And second, my main source (D/A converter) runs to my pre over balanced ICs.
Maybe I should just send my pre back to Pass to have them mod it. The cost to get all those external attenuators would probably be about as much as just having the internals adjusted.
Tboooe, adding an attenuator to your system isn't "wrong", it's just inelegant. You have a really fine collection of components and you should try to get the system right rather than kind of get it right and then apply what is effectively a band aid solution. Just my opinion.
Did you try decreasing the input gain on the BAT preamp (the one that is causing the music to be too loud even at the lowest volume setting)? Most if not all preamps have an input gain setting that can be adjusted up or down. So if it was set at zero, decrease it to -6 or more until you find a reasonable loudness. Just make sure you are decreasing the input gain that your cd player is connected to. That should do the trick. You will find that your volume knob will have more room to move instead of being stuck at volume setting 1 or 2 and the music is already too loud.
courtvision21, yes I have tried adjusting the BAT's "Relative Volume" for the cd input. It did make a difference though I find I am stuck at the 2-3 volume setting. I have tried another cdp that outputs 1.7v and the volume from the BAT is still too loud. Not sure what to do now...
How much did you decrease the input gain or as BAT calls it "Relative Volume" adjustment? Try setting it lower. If that is properly set, you should be able to use the main volume knob in a wider range. A CDP with 1.7V output is not high at all, so if even using a player with that output should not overload your preamp. Also make sure, you don't have the Fixed Gain mode "On" for the BAT preamp, cause that might bypass your input gain adjustment (I'm guessing???). If your Classe has 14 gain, and the BAT is 17 gain, that's really close. The Classe can go +/- 14 ticks of gain, so I am assuming the BAT can go +/-17 ticks of gain. So you should be able to lower the BAT to sound like the Classe in terms of gain input. Just go as low as you can, and slowly inch your way up on the BAT input gain. I think you should be able find the right setting after trial and error. If that doesn't work, something seems wrong with the BAT preamp then.
Ok, I have chilled out. I guess I haven't been very clear in my responses. Downunder has said it best and I will try his approach.
The stated gain of the preamp is the gain with the volume control all the way up. You never use it this way so the maximum gain doesn't matter. It doesn't matter if you put in a preamp with 1,000 dB of gain. I should not have said you have too much gain. I should have said that your amp already has enough gain to drive your speakers to uncomfortable levels.
In your sytem the output level of the preamp is less than the output level of the CD player. In other words, the preamp is always attenuating the signal.
You don't need a pre amplifier, you need a pre attenuator.
The problem is not the maximum gain of the preamps, it is that the amount of attenuation is not enough.
courtvision21, yes I have adjusted it all the way down (-40) and the fixed output is off.
downunder and herman...now that makes sense. thanks for the patience and helping me understand what is happening. Your responses are very similar to a what BAT just told me about their volume control. Again, thanks.