Replace C28 with... ?

In my previous thread regarding a power amp, some of you commented that replacing the McIntosh C28 preamp would make a huge difference. However, what was missing was any elaboration how why you made the recommendation, and with what to replace it.

So, let’s get down to it.
McIntosh C28
HiFiBerry DAC+ Pro (Yes, I know... sacrilege, but it’s all I’ve got for now)
Bryston 4BST
Dahlquist DQ10
Polk PSW650 sub

Need guidance from you guys on whether I ought to be looking at SS, Tube or even a Passive unit. Since I have some skill with a soldering iron, I'm not above entertaining the idea of a kit.

I’ve seen the Tortuga LDRx and that concept looks pretty interesting. My worry is that the DQ10s can be a bit aggressive on the high end with that ribbon tweeter, so I’d like to hear your thoughts.

Thanks again in advance!
It may or may not effect this thread, but the DQ10 does not have a ribbon.  To add one, someone would have to modify your crossover. I would assume that with  the comment about getting aggressive on top indicates that the piezo is there and not a ribbon.
Correct - my error, I mis-spoke - meant to say 'piezo'.  Back to the question at hand...
Disconnecting the piezo was a popular tweak back in the day when I owned the DQ 10. Give it a try!
The piezo can be modified or better yet,  replaced and the replacement modified.  Let me know if that is an interest.
Can we please focus on the question that was asked, instead of talking about the tweeter?

Sorry, I guess I can’t.. For some people this could be a welcome contribution. You Mentioned the ragged top end. A Preamp could contribute to this, but the tweeter could also be part of it. So I was only trying to be helpful.  I won't respond about your speaker again.
It might be helpful if you explained why you are replacing equipment.  Are you trying to achieve a specific sonic goal?
Not happy with my current SAE A202 amp - lacks staging depth, imaging is sometimes confused, it's a little thin, and not quite as musical as I'd hope.  Though it drives the DQ10s well enough, I think there's room for improvement, hence identifying it as the weak link in the system and replacing it with the 4BST. See my post here:

I listen to a wide variety of source material, mostly Jazz, Classical, traditional Rock and some pop, so I'm more or less all over the map.

Here are a few I have on the radar, in no specific order of preference, but need input from you guys who have more experience based on my equipment since I don't know what characteristics or advantages each may have over my C28:

Cary SLP-50
Threshold FET1
Krell KSL
Conrad Johnson PV14L
McCormack Deluxe Line Drive
Tortuga LDRx

Other 'non-mainstream' suggestions have been:
Prometheus TVC Reference

I looked at your other thread. Did you get the Bryston yet?
It’ll be here tomorrow. I’ll probably be sitting on the steps waiting for the UPS truck to pull up.

Another question to add to the list, is whether I ought to be looking for a Preamp with balanced outputs, since the amp supports that.
Why don't you wait and hook the C28 up? You just might like what you have now. Don't put the cart before horse!

Do you have plans on your future DAC? If you are just using the HiFiBerry as DAC, it may be extremely challenging to plan the proper preamp. In my experience, a preamp is just another tool in shaping the sound from the source.

You went towards a Bryston preamp. This is definitely on solid state side (no Class A, no tube). You are going to want to put some sort of tube or Class A device in your originating equipment. Your HiFi Berry is probably going to put out very weak sound - there is really no power supply capability in this - I think everything runs off USB power or similar. There is no beefy power supply to push bass/midbass weight or punch. I would suspect the sound is very thin. A powerful preamp may help translate more bass, but it will not change the source waveforms much. The type of DAC may influence the type of preamp you’re after. For the HiFi berry or a different solid-state type DAC, I might look at the BAT preamps because of bass translation (BAT is very good at bass). If you are getting a tube DAC, I would lean towards a very solid state preamp - like a Krell or even a Wyred 4 Sound STP-SE (which is almost like a passive preamp with gain voltage).

Most of your suggested preamps are seriously old school. The Krell is from 1992. Most of this stuff will have to be re-capped (electrolytic caps) for them to perform well. From the list, I would probably pick the Conrad Johnson just because of age. Though, if you tried to find a Krell KRC-3 or KRC-HR and then re-cap, that might be extremely nice.

Your HiFi Berry is probably going to put out very weak sound - there is really no power supply capability in this - I think everything runs off USB power or similar. There is no beefy power supply to push bass/midbass weight or punch. I would suspect the sound is very thin. A powerful preamp may help translate more bass, but it will not change the source waveforms much. The type of DAC may influence the type of preamp you’re after. For the HiFi berry or a different solid-state type DAC, I might look at the BAT preamps because of bass translation (BAT is very good at bass).
Excellent feedback - this is the sort of information I was hoping for to fill in the gaps of what I haven’t been thinking of, or knowledgeable about.

I have no plans for another DAC right now. So, based on your input, a tube would be the way to go, and I think we can rule out a passive unit because of the minimal power the HiFiBerry puts out.

Old school? Yeah, probably, but not as old as the speakers or current preamp, so that’s not a bad thing in and of itself. I know technology and materials research changes, but I’m not in a position to afford anything new, so I have to pick something that is pre-owned and falls in the area of my budget which is limited, to say the least.

So - in the SS vs Tube debate, what’s the difference in cost and characteristics between recapping or buying new tubes? Heck, talk about ’old school’, so do they even make tubes anymore or must I rely on old stock? I don’t want to paint myself into a corner by spending money on old technology that will be useless when the tubes fail because I can’t replace them.

Thanks in advance!
Y'know, one thing we may have overlooked... the Bryston is the PRO model.  Is it possible that a passive might actually work with this amp?

Well, fellas, I just took delivery of a 4BST Pro in a solid 8+/10 condition with 5 years left on the warranty.

Though I'm sure the C28 can be improved upon, in only an hour's time with the new amp I can already hear a decided change over the SAE.

Instruments are more 'articulate'
Imaging is more precise.
Staging is (surprisingly) both higher and deeper.

I can't wait to see what a new preamp will reveal. Though many have admonished me to look at a tube preamp, the diminishing availablility of 1940's technology worries me (i.e., ten years from now when the tubes need to be replaced there won't be any or they'll be a fortune), so I'm inclined to look at a SS unit.

Keep those cards and letters comin'.


When I say "old school", I really don’t mean anything negative about it. The circuits are all good. What I’m really saying is that you’ll want to replace all the electrolytic capacitors - they do dry out. The Krell KSL is from 1992!!

Suggestions would be based on what you feel you are missing. Do you feel like you are missing bass punch/weight and low midbass body? Or maybe bass is okay, but you’re missing resolution.

If I had the HiFiBerry, I think my first thought would be to go after the BAT VK3i there’s one for $899. That would give me the bass/body.  The BAT stuff has extremely good bass, but some find it lackluster in the high frequency detail and excitement. You could always start experimenting with tube choices. New tubes are still being made and the industry is not going anywhere.

Otherwise, there’s a Krell KAV-250p for $725. This will probably give you more resolution, but you’ll want to replace all the electrolytic caps.  Maybe look into Conrad Johnson to see what the general sound signature is like (I don't know anything about it)

The McIntosh stuff is generally very laid back and may feel like you are missing resolution. Since you like where the Bryston took you (with more articulate instruments, etc.), you may want to lean towards Krell (or that Conrad Johnson).

What’s your budget for preamp?

Budget is roughly $1000, perhaps a little more depending on the opportunity, but less is better if I can find something great (read: non 'mainstream') or a 'deal' and save money.  I'm only spending that much, because my hope is to sell the C28 when I find something I'll be happy with.

On the upper end, I have my eye on a Krell KRC-3.  It's more than I wanted to spend, but hopefully I won't have to do this again for many years.  Besides, if I were to get something less expensive in the $800-ish range and have to re-cap it, I'm up in that price range anyway.  Then, on the lower end, the Threshold is in the $500-ish range.

Good to know that tube are still being made.  I had visions of spending lots of money for a paperweight if tubes were no longer available.

Narrowing it down to a handful, prices all over the map:
Krell KRC-3
Conrad Johnson PV14L
Promitheus Reference TVC (not 'mainstream')
Threshold FET1

Can anyone comment on the differences between a Krell KRC-3 vs KSP-7B and if you think it'd go well with this system?

It's probably a wash between these two.  KSP-7B is from 1990.  KRC-3 is from 1995/96.  The both would need to be re-capped. 

KSP has an external power supply that is easier to recap, and has a phono preamp. 

KRC-3 may have slightly better input stage, not sure.  I would probably lean toward KRC-3. 


So, then if anything high-end that I could afford will be older and would need a $300-ish recap job, there’s some question about whether or not I should be looking at tube units so I could (theoretically) replace them more easily and even experiment with different tubes to change the characteristics to ’tweak’ the unit.

Still on the fence. Cripes.

Maybe I’ll just keep the C28 and buy some good Scotch instead.

Let me re-frame the question.

Given the preamps I listed above (there's also a very nice Threshold FET1 available...), what sort of improvements do you guys think could I expect over the current C28? I have an idea of what I *hope* to hear, but would like to hear your opinions on what changes I can look forward to.
I did something similar a few months ago.

I purchased a KRC-3 from eBay in March for roughly $1100 and spent less than $100 for 4 new Neutrik XLRs, 54 Nichicon Muse and ES Audio capacitors from Mouser. The Nichicons are actually an upgrade for this already fine line stage preamp. The orginal KRC-3 cost was $3,000 at introduction and had climbed to $4k by the time it was discontinued. The best way I can describe the "sound" of it is that it has little sound of its own. If the source material has gobs of depth then that is what I hear. The KRC-3 is feeding a McIntosh MC352 amp which powers Martin Logan Prodigy speakers.
A lot of my stuff is used because I want a certain quality but honestly I cannot afford these items new. I built my own PH-16 tube phono stage from and heavily upgraded it while building it. The PH tube sound is liquid and GLORIOUS!!! It sounds like music.

The BAT VK3 preamp was on my short list as well.

I run Balanced connects from my DAC  (Gustard X20u + Xingster SU-1 DCC). I also am cabled with XLRs to the amp as well.

I really wanted a McIntosh C2300 or C2500 but once again...budget.
I also looked into passive preamps but few ever showed up used and the cost new for a good one in the $2k-$4k range.
I was just about to click in here when mhztweaker posted the above.  Like him, I want a certain experience, but can't afford it new, so I have to look at (very) pre-owned equipment.

Just pulled the trigger on a KRC-3.  It's the earlier style with the more 'industrial' less streamlined faceplate, but the innards ought to be the same.

After all of this, I can only hope that a near 40 year-old C28 will be outperformed by a 20 year-old KRC-3.

Per the suggestion by auxinput, I might try to recap the unit, though that will have to wait until I can afford to do so.

Thanks to all for the very insightful input, it's been quite helpful!
The difference it tight bass, detail and top end extension will be dramatic,  you will loose your bloom.  They will definitely sound different,  you'll figure out your taste very quickly.  Purchasing used,  no matter what, you shouldn't get hurt and should be able to move one preamp without issue. 

You'll have to let us know how the KRC-3 sounds. 

I agree with mhztweaker on the caps.  I have spent the last several years modifying audio circuits and have gone through a great selection of capacitors.  The Nichicon Muse KZ are the absolute best, in my opinion.  They are extremely fast and very neutral (and provide very detailed sound).  Otherwise, if the KZ do not come in the proper rating or physical size, choose other Nichicon caps (like KW or ES, etc.).  Do not use any of the 105 degree and above caps.  The 85 degree actually sound the best.  I had several people at DIYAudio tell me to use 105 degree caps.  However, they really sounded bad - had some bigtime electrical resonance happening.  The 85 degree caps, and especially the Muse KG, are built to reduce electrical resonance as much as possible.  This is extremely important in audio circuits.  The 105 degree (and up) caps are built to operate in a higher temp situation (like in a car or industrial machines) and do not focus on electrical resonance.

I did not like the Nichicon Fine Gold FG series - they pushed the upper midrange too much for me.

The re-capping with Muse and other Nichicon will make a significant difference in your preamp.  Don't be afraid to increase the capacitance of the two main power supply caps (if you can).  However, the smaller pre-regulator caps should not be larger than about 330uf.  The small caps around the audio circuits themselves should not be larger than 47-68uf.  Putting large caps here will make the sound more laid back with less midrange.  Even 100uf is too large and too slow to respond to the upper midrange transients (you'll even lose some midbass because it's just not fast enough).

I'll report in when I get the unit and have a chance to listen for a while.

In a world of disposable equipment, it's amazing to think that some components were built to last and are worthy of this sort of attention.  My philosophy has always been: "buy it once, buy it right".

Not sure if I'm comfortable doing the recap work myself.  Soldering new components?  Check.  Removing solder?  Not so much.  I guess I'll live with it for a while and see what happens.

Quick question on the KRC-3...

How would you attach the Polk PSW to the preamp?  I read the Krell manual and it says that both the balanced and single-ended outputs are active at the same time but that it wasn't advisable to connect both at the same time to a preamp.  Does that also apply to the Sub?  My plan was to connect the two RCA leads to the inputs on the Polk, and use balanced going to the Bryston.

Your thoughts?

Not sure why the Krell manual states that both should not be used at the same time.  It looks like the traces on the board just connect the two outputs together (like a Y-splitter cable) as shown in the upper left part of the following picture:

It may be an issue with driving two different types of amplifier impedances, not sure. The other alternative would be to use a Y-splitter cable, which is doing the same thing and you have multiple cable connectors that are degrading the audio quality.  I say that you should just try connecting both XLR and RCA outputs and see how it goes.

I suppose you could use the RCA input/out of the Polk subwoofer to connect on to the Bryston amp, but you'll definitely be losing sound quality here.

If you have any interest, I would be willing to do the re-cap job for the cost of the components plus shipping plus $100-150 labor (depending on what you wanted done).  It's probably a couple hours of work for me.  If you don't have a good desoldering gun, it can be extremely difficult to remove solder and dis-attach the capacitors.  It is easy to pull up traces on the circuit board if you are not able to melt the solder enough - and you've just destroyed a $1000 item. lol. Sometimes you have to re-apply new solder and re-melt the contacts to get all the solder hot enough so that it lets go of the capacitor leads. 

Oh, expect to have a burn in time of about 250 hours with those Muse capacitors. 

Might just take you up on that offer, but not immediately. I think I’ll wait and see what changes the new preamp brings for a while, at least. Having borrowed the C28 back from my friend (it was out on loan for a while) I can tell you that I’m enjoying the HELL out of the new Bryston amp compared to the old SAE.

Right now I’m listening to Linda Rhonstadt / Nelson Riddle ’Round Midnight’ and it’s a dramatic improvement in every way. For example, the SAE used to put an edge on her voice and particularly in those long held notes there would be a brassy, shrill ’ringing’ that seemed to get stuck in the amp, and would just exhaust the hell out of me. Now? Gone.

Anyway, stay tuned. Send me your contact info so we can discuss sidebar.

What a tremendous difference.  If the Bryston really made a huge improvement, the KRC-3 took it to the next level.  Far better imaging, much more fluid midrange... a huge change.

Looks like the C28 will be going up for sale shortly.  Shame to let her go, but I'm sure someone will give it a good home.

Thanks to all for your input.
That's awsome.  I'm glad the KRC-3 worked out! 
What I expected to hear,  enjoy!  What about the tweeter?  Nevermind
I was thinking about installing a ribbon.  :-)
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