I agree, and that is what I have pointed out to RCV. That option would give him twice as much power (and more gain as well) and may defeat the need of a PRE amp altogether!May I suggest a 2nd ACA for a monoblock setup.
I'm running ACA's in bridged monoblock mode, driven by a unity gain Schiit Saga preamp. This combination sounds very good, and will drive my 94db, 8ohm speakers to much higher SPL than I want.
$-wise, the cost of a second ACA is a very reasonably priced upgrade.
I hear a lot of good things about the Whammy, though.
Probably can't go wrong either way.
That said, he already has 1 ACA and 2 passive PREs. So, in lieu of that, I suggested he try what he already has and, if that isn't enough then, whatever path he deems better: Active PRE or Second ACA.
Keep in mind he has 87 dB (perhaps 90 depending how you read the specs) 6 Ohm speakers. That is quite a different beast than your 94 dB / 8 Ohm speakers! My setup is more similar to his and I really needed that Pre.
On the other hand, for me building a second ACA was not part of the equation... I was very generously gifted a pair of old-format PCBs that are no longer in production and I made a chassis with the only 2 almost-up-to-spec heatsinks I could purchase locally. So in order to make a second identical ACA is near impossible for me. I would need to purchase 2 new ones with chassis from the store... and then I cannot listed to headphones
.So, for me, the path to WHAMMY was easier than the non-viable second ACA for now.
But yes, at the core, I agree with your statement!
Rafa.
I am not sure how could I have suggested that there was too much gain. I tried to say that low gain was not enough for me and I was using the PRE at full volume with less than desired output. I switched to high gain and I am now able to set the volume to good levels for my hearing needs.
Rafa, the sentence talking about too much gain from the preamp becomes true only if you switch to a more powerful preamp. For example the XCC balanced BoSoZ can produce a gain of 12 volts, more if you switch the gain resistor. It can produce enough current to drive an F4 and produce lots of clipping in an A3X. As long as you stay where you are you have a nice viable combination with no need for attenuation. If you upgrade the preamp to something beefier you may cause the ACA to clip, ergo the need for an attenuator to solve the problem caused by the excess preamp gain.
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I agree, and that is what I have pointed out to RCV. That option would give him twice as much power (and more gain as well) and may defeat the need of a PRE amp altogether!
That said, he already has 1 ACA and 2 passive PREs. So, in lieu of that, I suggested he try what he already has and, if that isn't enough then, whatever path he deems better: Active PRE or Second ACA.
Keep in mind he has 87 dB (perhaps 90 depending how you read the specs) 6 Ohm speakers. That is quite a different beast than your 94 dB / 8 Ohm speakers! My setup is more similar to his and I really needed that Pre.
On the other hand, for me building a second ACA was not part of the equation... I was very generously gifted a pair of old-format PCBs that are no longer in production and I made a chassis with the only 2 almost-up-to-spec heatsinks I could purchase locally. So in order to make a second identical ACA is near impossible for me. I would need to purchase 2 new ones with chassis from the store... and then I cannot listed to headphones
So, for me, the path to WHAMMY was easier than the non-viable second ACA for now.
But yes, at the core, I agree with your statement!
Rafa.
Rafa, thanks again for your insightful tips.
Actually, I ordered two ACA kits. The reason I need a preamp is to control the volume. Most likely, my major source will be a cd player, since I have a collection of CDs. For sure, I will also try other sources, like a laptop or ipod where I can easily control the volume. In the latter sources, I guess I won't need a preamp.
I use preamps to set balance, like with the FirstWatt B1 which has two seperate pots. Volume is easily adjusted in the media player.
Maybe this is an opportune time to get clarity on this from the experts. I'm a relative newbie and the way I understand it, attenuation of the signal level is just one function of a preamp. Another function is the role of a buffer; ...taking care of impedance mismatching between the source and the main amp.
As mentioned before I can really recommend Rod Eliotts P88 preamp. It's a rather quick and easy build, gain can be set between 3db and 12 gain with the change of a few resistors. There's a balance control and volume control (obviously) and the project is really well documented.
My version of the P88 ist still on a breadboard and works very well with the ACA. It's currently set to 6.9 db of gain which seems to be enough. To make a long story short - with a breadboard and an investment of something like 15 bucks one can build a nice little preamp and give it a try with the ACA.
My version of the P88 ist still on a breadboard and works very well with the ACA. It's currently set to 6.9 db of gain which seems to be enough. To make a long story short - with a breadboard and an investment of something like 15 bucks one can build a nice little preamp and give it a try with the ACA.
DAC is a Schiit Gumby, which was my initial foray into what I consider "high dollar" stereo equipment. It was difficult to convince myself to pull the trigger on buying it, but I'm glad I finally got over my trepidation.
Schiit front end is working very well for me.
Choice of Aleph J was on the recommendation of 6L6 (and others) plus a little help from a guy on diyAudio that came through with a set of none too common Toshiba input JFETS.
I can take my time on the AJ, though, these ACA's are still revealing things to me about my system and music that I was unaware of, and doing so in fine style. Just glorious sound, really.
I see no Grumbys in the Schiit product list, do you mean the Gungnir? If you do, it is a beautiful piece of work, dual power supplies, dual analog stages and true balanced path throughout. The output is 2 volt RMS unbalanced and 4 volt RMS blanced. This is also my choice backup for DAC if the kit I am planing to build (old OPUS kit I had bought but not built with a WM8740 DAC chip, dual mono balanced configuration) does not work for me as expected. The preamp I am planning to build is also an old kit, a Twisted BoZoS I had bought but not built and also in dual mono balanced configuration (kind of a clone of the XCC balanced BoZoS, for which PCBs are still available from kk-pcb.com). Of course my intention is to put together a true balanced signal path from the source to the ACA. We will see, I see no reason to speed things up and build the stuff in a couple of weeks. I am planning to do this very slowly with plenty of time assigned to other more important needs but it will get there. And also, of course, before I start I will make sure to read the jillion pages in the diyaudio threads, sometimes OCD pays.
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That's the right unit (Gungnir), excellent btw.Not sure who or how the nickname "Gumby" was introduced? Gungnir is pretty far from Gumby, but who knows...
I should have started with the correct name.
Gungnir Multibit = Gumby, a nickname I kept coming across in various forums.
Saga lacks balanced signal path. Freya has it, but tube outs are gain of +5, fixed. If it would have had the option to run the tube outs at unity (or even better, variable) gain, I would probably have gotten it.
I'm wanting to try the ACA's balanced. They and the Gumby are the 1rst pieces I've ever owned that would support that usage.
Now I want a balanced, tube buffered with variable or readily changed gain preamp.
Never ends, does it?
Gungnir Multibit = Gumby, a nickname I kept coming across in various forums.
Saga lacks balanced signal path. Freya has it, but tube outs are gain of +5, fixed. If it would have had the option to run the tube outs at unity (or even better, variable) gain, I would probably have gotten it.
I'm wanting to try the ACA's balanced. They and the Gumby are the 1rst pieces I've ever owned that would support that usage.
Now I want a balanced, tube buffered with variable or readily changed gain preamp.
Never ends, does it?
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Are you sure of the fixed output of the tubes at +5 v? The way I read the specs is that the JFET buffer will give you a gain of 1 v (no gain), and the tubes will give a gain of 2.5 v (presumably for the single ended outs and also presumaby +5 v for the balanced outs). I read these specs as giving the max gain at the output. Of course the preamp has a volume control that should let you vary the gain of the unit that is passed to the amp. The issue then would be whether a 5 v gain, balanced, is enough for you. Why don't you email Schiit and discuss this issue with them. With a price differential between the two units of $350 they may let you switch.
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For the sake of clarity I think we should use the proper terms when discussing gain and voltage levels. There seems to be some confusion here over terms. Gain is Voltage out/voltage in and is expressed as a number or also commonly in Db. It does not include the unit Volts. So a gain of 1 has no units and should not be stated as a gain of 1v. If for example the input to an amplifier is 1 volt and the amplifier gain is 5 then the output is 5 volts.
I was wrong about the Freya tube stage gain being 5, it is actually 2.5.
I understand gain to be a multiplier applied to the voltage input to the gain stage of a preamp, and that volume control is an attenuation applied independently of gain that can only reduce.
Help me make sure I understand this correctly.
Let's start with SE (unbalanced) in our example here.
Max SE output of the Gumby is 2.0v RMS, this is the input to the preamp.
If gain is a multiplier then:
2.0v RMS to a preamp with a gain of 1 would equal 2.0v RMS max out from the preamp.
2.0v RMS to a preamp with a gain of 2.5 would equal 5.0v RMS max out from the preamp.
So then, the max output of balanced signal from the Gumby being 4.0v RMS,
the max output voltages for preamp gain of 1 would be 4.0v RMS, and preamp gain of 2.5 would be 10.0v RMS.
Yes? No? Are we saying the same thing different ways?
Mazeppa, look at the Gungnir specs published by Schiit. Max output, line 4, it lists 4 v RMS balanced, and 2 V RMS single ended. The balanced mode doubles the voltage RMS of the output single ended. So, if you get your signal in balanced form to a preamp or directly to your amp, you have a max gain of 4 V RMS going into the next piece of equipment. This will be amplified at each separate stage of the way until it goes out the amp to the speakers.
You do not have a balanced preamp and there is no provision in the Saga for a balanced input. The single ended output of the DAC goes at 2 v RMS into the Saga, and this is my confusion because the specs cite a gain of 1 which is 0 gain, but a max output of 10 v RMS. So I really do not know how to interpret what level of gain (vs max output) you may get into the ACA this way. Sorry about that. You need to clarify this with Schiit.
Now the Freya has both single ended and balanced inputs and outputs. It has a gain of 2.5 v RMS gain (8dB) as per the specs. However the specs do not break down the max output obtainable from the unit using single end outputs vs balanced outputs. I would tend to think that if the 2.5 V RMS gain is single ended, the balanced output should have a 5.0 v RMS gain. However Schiit does not say so in the specs, and I am not certain my thoughts are correct when I say the balanced gain should be 5.0 v RMS. I think you should email Schiit and ask them if this is correct or not.
Any signal with or without gain fed to a preamp or amp will be amplified by the preamp or amp to a higher level up to the capability of the preamp or amp. If the signal you feed the unit is too strong for it to handle, the amp or preamp will clip and you will have to attenuate the feed signal.
The beauty of the Gungnir + Freya combo is that the signal is put through a true balanced pathway from the source up to the ACA. Since I have never had or heard a true balanced signal path system (source to amp), all I can say is that I hope the effort will be rewarded with better results than what may be obtained will an all single end signal path, or a hybrid path (partially single end and partially balanced). I really do not know what the end result will be since I have never experienced such a system in operation. And yes, the sky is definitely not the limit for me, or for most other people.
I have been reading a lot, including Nelson Pass articles, and he describes two schools of thought in music amplification: The objective school which is based upon strict measurements of distortion or what have you, and the "hearing" school which is based upon what the music sounds like. I believe Mr. Pass favors the second school of thought and is quick to emphasize that some degree of harmonics (2nd or 3rd degree harmonics) may make the music sound better. This school of thought also describes that an amplifier which is provided with a strong signal may retain enough reserve capacit to react to high musical transients appropriately, while an amp that is operating at full tilt at all times may have some degree or considerable problems with these transients. Descriptions like dynamic music reproduction and music staging detail are used by the "hearing school" and apparently by Mr. Pass. This is just for information and to serve as a basis to judge the results obtainable from the ACA.
I really wish you all the best with this project.
Your thoughts in this regard will be appreciated.
You do not have a balanced preamp and there is no provision in the Saga for a balanced input. The single ended output of the DAC goes at 2 v RMS into the Saga, and this is my confusion because the specs cite a gain of 1 which is 0 gain, but a max output of 10 v RMS. So I really do not know how to interpret what level of gain (vs max output) you may get into the ACA this way. Sorry about that. You need to clarify this with Schiit.
Now the Freya has both single ended and balanced inputs and outputs. It has a gain of 2.5 v RMS gain (8dB) as per the specs. However the specs do not break down the max output obtainable from the unit using single end outputs vs balanced outputs. I would tend to think that if the 2.5 V RMS gain is single ended, the balanced output should have a 5.0 v RMS gain. However Schiit does not say so in the specs, and I am not certain my thoughts are correct when I say the balanced gain should be 5.0 v RMS. I think you should email Schiit and ask them if this is correct or not.
Any signal with or without gain fed to a preamp or amp will be amplified by the preamp or amp to a higher level up to the capability of the preamp or amp. If the signal you feed the unit is too strong for it to handle, the amp or preamp will clip and you will have to attenuate the feed signal.
The beauty of the Gungnir + Freya combo is that the signal is put through a true balanced pathway from the source up to the ACA. Since I have never had or heard a true balanced signal path system (source to amp), all I can say is that I hope the effort will be rewarded with better results than what may be obtained will an all single end signal path, or a hybrid path (partially single end and partially balanced). I really do not know what the end result will be since I have never experienced such a system in operation. And yes, the sky is definitely not the limit for me, or for most other people.
I have been reading a lot, including Nelson Pass articles, and he describes two schools of thought in music amplification: The objective school which is based upon strict measurements of distortion or what have you, and the "hearing" school which is based upon what the music sounds like. I believe Mr. Pass favors the second school of thought and is quick to emphasize that some degree of harmonics (2nd or 3rd degree harmonics) may make the music sound better. This school of thought also describes that an amplifier which is provided with a strong signal may retain enough reserve capacit to react to high musical transients appropriately, while an amp that is operating at full tilt at all times may have some degree or considerable problems with these transients. Descriptions like dynamic music reproduction and music staging detail are used by the "hearing school" and apparently by Mr. Pass. This is just for information and to serve as a basis to judge the results obtainable from the ACA.
I really wish you all the best with this project.
Your thoughts in this regard will be appreciated.
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rnjorge, nothing to be surprised in your experience. Yes, some systems interact together in a much better way than others do. The quality of the music you hear will be changed when you use different preamps or DAC's and the same amps and speakers. I agree your ears should be in control to decide what equipment you are going to use. By the way the B1 is a Pass design same as the ACA's. The Saga is a Schiit design, not the same as the ACA's..
