Budget preamp with quality volume control


Dear Audiogoners,

I used to be a firm believer that the signal path should be as short as possible and, as such, I have been using the two-channel system without a dedicated preamp. For a long period of time, I have relied on the digital attenuator in DAC for volume control, knowing the digital attenuator would compress the dynamic range of the sound. Therefore, I switch the volume control on DAC to the fixed mode, bypass the digital attenuation and use the unity gain knob in the back of the power amp for volume control. Depending on the music recording level, however, sometimes I need to turn the unity gain control way down to get proper sound level. This is particularly painful when I use the full-balance connection because of the double voltage gain.

In short, I am looking for a budgetary preamp with quality volume control that either has relay switch stepped control or precise potentiometer for left-right channel match to curb the issue. I try to summarize important (to me) performance catgories as best I can for various good sounding preamp I know (with or without headphone amp/dac) as shown below. It is found the Schiit Magnius happens to have the highest performance ratio. However, I am pretty sure that I likely miss other good performers due to my limited knowledge and would like to solicit for your inputs. Your kind assistance is appreciated.

 

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I actually enjoy to read about the hardship that Steve Huffman went through when he heard the transformer buzz/hum from his over $10k Luxman and then found the Puritan 156 to finally tame it down. My Parasound amps have a bit transformer hum as well that I need to 2 ft close to hear it but is enough to trigger my irritation.  I was doing the similar things, i.e., DC offset and Monster power conditioner, trying to get rid of it but without success. It is tempting but I could not justify spending $2k to cure the hum of $1k amp.

I found a used mPre selling for $700.  Is it a fair price? It is such a pity that its DAC section only supports up to 24/96 (usb) and 24/192 and no DSD. Well, let me sleep on it.  

Yes, $700 is fair used. You would probably just have to update the firmware through a USB download. Make sure the seller has the original box, packing materials and manual so if you wanted to sell it at a later date.

With mine I don't intend to keep it as Wyred 4 Sound let's you trade in or should I say trade up when bought directly from them. I agree with you that the dac is the weakest link, but it's built like a tank with shielding and other positives and at the time I just needed a reliable head unit on the cheap and usually in those circumstances the dac is what it is.

Even though I have thousands of cd's and hundreds of 'albums', as I said in an earlier post I am a crate digging needle dropper and I mostly use my turntable and can always upgrade and invest in a separate dac at a later date since I already own a cd transport. And that's exactly why Wyred 4 Sound made the mPRE the way it is cause it is essentially a head unit/pre amp 'starter kit'.

Late to the party; Schiit Freya+ here as well. Initial money saved on a comparable pre will get you into upgraded dac, (if wanted) ect. Season with NOS tubes of your choice whenever upgraditis hits; as opposed to spending 4K on a newer,"better" pre.

You want a good preamp? Find yourself an Apt Holman that's been recapped. Has the stepped precise volume control you want. Yes, it's 40 years old but there are few better "budget" preamps on earth.

I would agree with above find an older badboy. It will mop the floor with a new cheap  one. I would personally  look for an Ayre k1xe  or k3 or a canary 800 pair. The old classe Dr series would be great a threshold  fet 10e etc get yourself  a top pf the line older unit.

The classic Adcom gfp 750 and Apt Holman recapped can still be found at a affordable price but Ayre k1x or Threshold Fet 10e would cost over $2k.  They must be the crown jewels top of the line back then.  Thanks for the recommendations.

I was looking through this post and thought - if I am only using the ONE digital source - would I really need a pre-amp at all? After all, a preamp deals with the switching of inputs (and I only have the one input) and also gain control but there's enough gain on a digital device anyway (broadly speaking).

I would need an attenuator - not a pre-amp (if you can distinguish the two) - so perhaps a high quality passive will do for me with no selector knob and only attenuator control. However, I would still need this single pot to be of high quality too - anyone know of something?

Ideally I would like a r/c attenuator if that's possible.

@chopandchange 

if I am only using the ONE digital source - would I really need a pre-amp at all?

That has been a question asked by many over the years.  Having enough voltage is one piece of the puzzle but impedance compatibility to drive the cables and power amplifier is another piece that is not addressed by simply putting an attenuator in the signal chain.   In short, many have found that preamps having a high'ish impedance input and low'ish impedance output to the power amplifiers seem to do a better job of preserving tonal qualities, dynamics, and drive, compared to using an attenuator alone.  A unity gain buffer following the attenuator can do the job fine in cases like yours where there is enough voltage coming out of the source.   

In-line attenutor is just a fixed output passive preamp as opposed to passive preamp with variable levels of attenuation. Not clear what "Indus" is but if Rothwell refers to their in-line attenuator, the output impedance is stated as 3750 ohms, a bit lower than the Schiit SYS (5k) but still high enough to reduce the impedance ratio (approx. 8.6) down below the desired 10. Note that the cable I was using is merely 12 inch long and my Parasound amp has a reasonably high 33k ohm input impedance. It is still likely the company’s in-line attenuator will impact on the sound quality as SYS does. As such, I have no longer considered the passive preamp or in-line attenutor option.

Some active (with gain) preamps also have attenuation function in addition to amplication, such as SPL Volume 2 (-4 dB) and some others. All the Schiit active preamps starts from a "amplication factor" (Schiit refers it as "gain") of 1 which gives no volume (dB) increase/decrease. The formula is 20*log(amplication factor). So amp. factor of 1 give 0 dB. When the amplication factor is less than 1, say, 0.63, change in volume is 20 log(0.63) = -4 dB (like SPL Volume 2 mentioned above) indicating that the preamp is actually performing attenuation. Those active preamps with gain is exactly what I am shooting for.

 

Every passive attenuator company says the same thing, Goldpoint, the LDR folks (i.e., Lightspeed and Tortuga), manufacturers that put attenuators in their DACs like Metrum and Sonnet, and more.  Some say it louder than others.  Hattor/Khozmo offer both options, as well as op-amp or tube active stages to follow their passives, if desired.  I have tried more than a few passives, and currently own 5 different passive units, Goldpoint, Khozmo, Hattor, Endler (attenuators that mount to your amplifiers), and an icOn 4PRO autoformer.  I have also owned the Metrum Adagio DAC, with a lossless volume control.

The ONLY one of those passive solutions that IME preserves the tone and drive to the same level of an active preamp (or active buffer), regardless of how short the ICs are, is the icOn 4PRO AVC preamp, which uses Slagle autoformers.  The autoformers (a type of transformer) have the ability to decrease the output impedance while performing attenuation.  I really like the sound of the 4PRO but I also have a custom, higher quality, Khozmo dual mono passive unit that I use in front of a SMc Audio solid state unity gain buffer, which results in a quite low impedance signal going to my amplifiers.  I like the sound of the Khozmo/SMc buffer combination a little bit better than the icOn 4PRO.  The buffer does not provide gain (above unity), but with the buffer in the path following one of the  passives, I hear improvements in bass, dynamics, tone, and drive, over using any of the passives (except for the icOn) without the buffer.  The icOn 4PRO does not suffer the losses described above that I hear from the other passives.

All that said, only you can decide what type of sound you like, and what you hear in your own room with the equipment you have.  There are many here who like having a passive attenuator, and are happy with the sound.  In the end, any of us here can describe what has worked for us but "try it for yourself" is the only answer that really means anything.

I did see the icOn 4PRO in action at an Audio Show - very impressive - and a very easy to use remote because it’s taking advantage of the Apple r/c.

I think that would be my choice if I were to go for anything. Helped further by your endorsement and experience with other passive preamps.

The other popular choice is the Music First - but the icOn has great convenience features in comparison.

If u have gain issues do not touch the topping pre90. It ONLY worked for me with amps that had gain adjustments, such as the Benchmark AHB2 and the Parasound A21+. It was terrible with about another 5 amps I used it with.

The Sxhitt Freya+ has a lot of features and sounds OK,, but does colour the sound.

The Schitt Sys maybe something that woks for you. It only supports RCA.

You can always bite the bullet and get what I think is an amazing preamp and any price, the Benchmark LA4.

Music First Audio was an early adopter of the transformer volume control, or TVC.  I believe they use S&B transformers.  Transformers use two coils around a core and offer isolation while autotransformers, or autoformers, use only one coil and do not isolate but do apparently have a few advantages when used as volume controls.

Autoformers allow for the same voltage/current transformations that typical transformers are used for and have increased power handling capability, flatter frequency response, lower insertion loss and lower distortion than conventional transformers of similar size and cost.

I do like the Apple remote functionality with the icOn 4PRO.  I also like the large display that is so easy to see across the room.  Functionally, it offers everything I want in a preamp, including an HT pass-through.  I have not tried Music First or any of the other transformer VCs, so cannot make a comparison between autoformers and transformers in my system.

Music First Audio is a subsidiary of Stevens & Billington which is why their products use those transformers in their design. When S&B used to let people use the transformers for DIY and OEM John Chapman at Bent Audio built a very nice passive preamp with them and when S&B pulled the plug on DIY and OEM he switched to the Slagle autoformers and developed his own module with relays. If you can find one of his preamps used it would be worth trying out.

I have and have had many passive preamps over time that used quality attenuation controls. Everything from a simple pot in the box using NOS Noble potentiometers to Khozmo, Slagle AVC, and S&B TVC passives (all of which I DIYed and all had dual mono attenuation). While all of them performed well for me, the best bang for the buck in my opinion is the one I didn’t DIY which is the Lightspeed Attenuator.

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I had the Rogue RP-1 and found it to be an excellent preamp.  A modest windfall permitted me to trade it towards an RP-7, which I have found to a most excellent preamp.  While not exactly a “budget preamp,” the RP-1 is worthy of consideration, and, as you light out, it has a number of great features.

Yeap, it is under my radar. Did you find the tube in RP-1 changes the sound signature as compared to SS pre? I often heard the tube (for other preamp) just serves as a buffer and does not change the sound at all. But I hope that is not the case here. Also, have you tried the tube rolling before and does it change the sound?

The adcom gfp-750 linked earlier listed on usam is mine 

it is a very fine piece 

 

I have used a freya + but I found it to be not as full sounding as the adcom 

 

or my van Alstine , audio research or B&k for that matter

Not maybe what you want to do but have you considered making  your own passive. I have just made one myself using a TKD potentiometer, much better than the often touted Blue Alps. 

I will second the PS Audio Gaincell... I paired it with a Parasound A23+ amplifier and this combo blew me away with a pair of Zu speakers. Also played well with my KLH Model 5's. I have a Denafrips Venus II 12th DAC and find the DAC in the Gaincell to be much better, so much so I am selling the Venus and my Athena preamp. The sound is very dynamic, with a huge soundstage. I normally detest chip DACs, that digital sheen really fatigues the ears. I have had no issues with listening for hours to the Gaincell. And the folks that have heard it are saying the same. 

Give the Audionics BT a try.  A great sounding preamp (voiced like an Audio Research SP-6 ) with a buttery smooth volume control.

@ditusa 

I use NOS 6sn7GT Ken-Rad (Pre-Ge) staggered plates with black carbonized glass.

Is this tube the VT231 version? Where to buy? The link you left is not working. Thanks

@tyray Wrote:

Is this tube the VT231 version? Where to buy? The link you left is not working. Thanks

Yes! Call Andy at Vintage Tube services, knowledgeable man. See below:

Mike

https://vintagetubeservices.com/

 

@clio09 Hi bro, may I seek your advise which one should I get ? Music First pre-amp (used) or Khozmo pre-amp (new) ? Music first 75% expensive than Khozmo in my country. Many thanks!