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Hicap TPR4 on NAXO not right...

M

MRM

pfm Member
Hi all,

I don't post very often, but regularly pick up any posts of interest. Consequently, I thought I ask those who've installed a TPR4 if they have any ideas why I'm not getting the result I thought I would...which was no real change to the Naim sound, but more detail and a bit of tightening up.

System: CDS2 82/Supercap NAXO/Hicap 2xNAP180

Having read several posts all praising the Avondale TPR4 and having Minicaps installed in my NAP 180's by Witch Hat previously, and being really pleased with the result, I decided to take the plunge, and although I'm not particularly skilled in this area, I thought the soldering job simple enough that I would be able to do it. So TPR4 purchased and installed in a Hicap powering a NAXO. No issue soldering...all good connections, so powered it up...left it a while and tried it...lots of sparkling treble, but little bass and midrange is too light. The sound is no longer forward, but more laid back. And the best way I can describe it is that it's almost like everything has gone up an octave. Voices now have sibilance, where they didn't before. Left it a day or two, no real difference...I can hear lot's of detail, vocals for example have more nuance, but the voice sounds lighter and has no depth.

I checked the pots in the NAXO and spent a day or two fiddling with them...bit of an improvement if I drop the High frequencies quite significantly and shove up the levels for the low frequencies quite a lot... miles past the Naim marking.

Checked the DC voltage and it was set to 24.9V. Tried increasing it incrementally, and found a reasonably good improvement...it's at 26.5 now, but it's still not as musical as the old Naim regulator and still feels a bit lightweight.

I've swapped the cables between: Supercap and Hicap, and Hicap and NAXO, for spares. Didn't make any difference.

So, any ideas. What can I safely increase the voltage to? Should I?

Could it be the CAPS in the Hicap? I didn't change those...they are BHC and about 6 years old.

Regards
Mark
 
Here I go again: to me the TPR4 is over hyped on pfm. It sounds like a standard hicap regulator because it is based on the same regulator. Sure it has a tracking pre-regulator so it is an improvement on a standard hicap regulator, but to me it sounds essentially the same, a bit more detail. That is it. Hard to tell the difference to be honest. Feel free to call me cloth eared and I await the usual "TRP4 was the biggest change I ever made" statements. I am glad it worked for all those other people on pfm, I tried it, I sold it. Enough said.

Naim hicaps output about 24.7V. I would not keep just turning up the wick in the hope of an improvement. At some point something will go bang, more experienced hands in the diy forum can probably tell you where that is likely to be.

I don't see the caps as the issue, they are the same as when you had the Naim regulator in there, and they are only 6 years old, so unless you keep your kit turned on and enclosed so they run really hot they should be good for many years to come.

The LM317 used in the TPR4 and the standard hicap regulator has a "sound". To get a real change, you need to change the regulator. I did this by using an RSL PSM-1 module. You might try that or a Teddy Pardo PSU. These are fundamentally different regulators.

EDIT: Oh, I also ALWSRed my NAXO ...
 
I don't really have any suggestion that'll help but my experience of Hicaps vs other power supplies for naim matches yours and I've tried a number of different ones. The others lose some upper bass/lower mid weight. I'm not sure if the others are right and the hicap wrong but when you're used to it, you miss it when it's gone.
 
Oh, one more thing I remember, when discussing power supplies with Kit Ryan he felt that the highest gain (e.g. preamp) would benefit most from the RSL PSM-1 and that the effects would be less on a NAXO ...
 
I don’t know if that may help but I have a rather good experience with the Avondale TPR4 myself.
I am now the happy owner of a Naim NAC 32.5 with Neil Jadman’s cards/CB Hicap with TPR4/NAP 160 BD in its original form, freshly recapped.
I did the upgrades myself one at a time to hear the difference and they all were major improvements.
The TPR4 kept everything from the Naim sound, softened the treble a bit and made the female human voices sound more natural, just like if they were in the room with me.
I would add that the TPR4 removed any kind of harshness that is typical to the chrome bumper units so I only see benefits.
I listen to rock music mainly and also jazz so dealing with medium quality recordings randomly, this may influence my sound signature preferences, I guess.
The TPR4 was a bigger improvement than the Neil Jadman’s boards.
 
In my case I have a set of Naim bolt down era equipment. All recently serviced by Witch Hat. The 32 now has a dual rail power supply as has the NAXO. Each is powered by its own SNAPS fitted with Witch Hat's NEWT regulators. Very happy with the sound. I can't really compare too well with the previous sound as everything was overdue a service, only the 250s had been serviced at any point since 1977.
 
An interesting subject to me, because I recently purchased an Olive NAXO 2-4 which will go back to Naim to have the crossover reset for Kans (Naim HQ are quite busy at the moment). The main benefit will likely be the move from the single rail CB NAXO that I currently use to the dual rail employed by the later 2-4. I will be powering it with a homebuilt Avondale TPX. I have a TP4 modified hi-cap in the office system upstairs btw driving a NAC 42.5 and my experience was really positive, though it's true to say that it may have been overdue for a service anyway. It is a bit of a minefield though, as I recall back in the day when I ran active Saras. I had a NAC 32/Snaps, NAXO snaps & subsequent upgrades to 32.5.Hi-Cap & NAXO/Hi-cap, didn't really take me in the direction that I was looking for. I am hoping that once I get the 2-4 sorted, that it will take the system performance to a different level, but who knows!
 
I can appreciate that different power supplies, the teddy cap, etc. might give a different presentation. No issue with that, but all I'd read about the TPR4 seemed to suggest, as Gervias says "The TPR4 kept everything from the Naim sound". The issue I'm having is that it hasn't...that's what I wanted, but was hoping for a bit more of everything, and hopefully a bit more control. What I've got is a completely different presentation with some stuff being virtually unlistenable... unless I reduce the high frequency level drastically in the NAXO, and upp the low frequency level to get some bass, which can't be right surely? Tears for Fears for example on Head over Heels sound like they are banging a cardboard box not a drum. True the upper bass has lost the 'Naim' hump, and there's more control, but it's a cold, shouty presentation. The old Naim regulator was streets ahead in terms of musicality...makes me think something is wrong...I'm struggling to believe that a regulator can have so drastic an effect.
 
MRM said:
...I'm struggling to believe that a regulator can have so drastic an effect.
Click to expand...

I agree with you & it does seem that there may be a fault elsewhere, as that certainly hasn't been my experience of the TPR4, albeit not powering a NAXO.
 
Reading between the lines here I'm going to suggest the problem is with the SNAXO. You see they're not that keen on capacitive loads (Naim's own 4 pin leads for example) and can oscillate at RF. This would give you the sibilance you're hearing. An un-serviced unstable 250 does similar things.

As you haven't changed the SNAXO but merely given it a different PSU, then something worth trying is to re-arrange the leads at the rear, it may improve things. A handheld radio on an AM frequency in between stations might be able to pick up something if you can wave it near the back of the SNAXO and it is unstable. I haven't tried this method so can't tell you if it'll work but it's worth a try.
 
My original 1977 bolt down NAXO before servicing had odd noises audible with your ear close to the speakers. Silent now after service and the system benefits from Witch Hat Morgana cables.
 
If you are having to do a lot of adjustment from the previous NAXO settings, there is something wrong.

A new regulator might bring a little more or less of this or that here or there but I can't see it could massively adjust the balance in the way you are reporting.

I can only assume there is something wrong, I bow to MJS's experience, perhaps there is now a stabilty problem. Perhaps in the TPR4 install somehow the internal hicap wiring was disturbed? I might be tempted to put the Hicap regulator back to see if that fixes it.
 
certainly my tpr4 in a snaps was brilliant - i compared to teddy cap and hicap and the teddy was leaner and the hicap full and meaty with the tpr4 in the middle. Deffo sounds something not right.
 
My experience of the Snaxo 2-4 (meaning a properly serviced one) is that it's relatively insensitive to the quality of the PSU in complete contrast to the preamps.

I generally got little improvement in switching between the HC and various upgraded alternatives and even going to a full SC was a very minor upgrade.

(the Snaxo 3-6 is a different matter entirely so don't "read across" but with that I found the original SC preferable to a Teddy SC)

It may be that there just isn't the improvement to be had compared with the OP's expectations.

OTOH the large and less than positive difference he's actually experiencing may well suggest the Naxo isn't in peak condition
 
Hi All,

Thank you for the replies. I've tried rearranging the leads a bit; might be a bit of a difference, but hasn't made a bid difference...Thank you for the suggestion though MJS. I might consider unplugging all the kit and cleaning connections. Tidying the cables a bit more...it's not easy to get to where I have to situate the kit, but might be worth it.

Colsablue, I really wasn't hoping for bags of improvement...about the same as you'd get from a recap would have been fine.
Also the NAXO was recapped by Class A in 2014, so ought to be ok, but anything can fail I guess. Only thing I can think to do that will really tell me, and as nobeone said, is put the old Naim reg back in and see if it still sounds off...

Regards
Mark
 
Hi All,

Just wanted to give an update and share the experience. I decided to persevere with the TPR4 a bit longer, rather than swapping straight back to the Naim reg, and after about a week since the last post, the bass came back in...too much in fact and I was able to set the NAXO back to the Naim markings. Unfortunately, this still had a bit too much treble, so I backed the pots off a little bit and the balance is now quite good...with one issue...the sibilance is still there and annoys the hell out of me. I confess I don't understand why the sound has come back; I didn't change the big caps at all at any point, so wasn't expecting that much of a wait until everything was on song...forgive the pun.

I did google the sibilance issue and sifting through found a post on the Naim forum from a user that added a DR Hicap, who said that the sound changed for 'weeks', beginning with no bass, then getting sibilance, then a bass hump, then it settled and the sibilance went, the bass tightened and all was well. It's this post that prompted me to persevere, and it has got better...here's hoping!

Regards
Mark
 
Hi Mark,

I use a TPR4 equipped Hi-Cap to power a SNAXO 362. I’ve had none of the issues you have experienced. I preferred it to the ‘native’ Hi-Cap. Hence I think something else is wrong.

Martin
 
Hi Martin,

Good to see that someone else has a TPR4 Hicap on a crossover; all the posts I'd seen before related to powering a preamp, so I did wonder if something didn't gel with the NAXO somehow. Everything else is ok now, apart form the sibilance...
I've tried different interconnects and replaced Snaics with some older ones I have knocking around...tried to dress the cables a bit better, it didn't make any significant difference. I did read a post saying that someone had sibilance and it was fixed by replacing the Burndy. That's not so easy to do though, I don't have one lying around and it is quite an outlay...which may be for nothing. I plan to leave it a couple more weeks and see if it improves. If not I may put the Naim reg back in to see if the sibilance disappears.

Mark
 
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