NAD 304 integrated amplifier - Sounds too bright after upgrade.

NAD MAD

Novice Member
NAD 304 integrated amplifier - Sounds too bright after upgrade.

I recently had my NAD 304 amplifier upgraded with the components listed below.
  • Main Power Supply Capacitors > Nichicon LKS with increased capacitance.
  • Primary Capacitors in the Regulated Supply > Nichicon UFW
  • The remaining Regulated Supply Capacitors > Nichicon Muse with increased capacitance.
  • All other Capacitors in the Audio Circuits > Nichicon Muse, Fine Gold, Muse ES type.
  • Resistors were also upgraded in the Phono Amp, Pre Amp, Pre Amp Inputs, Tone Controls and Power Amp > Metal Film Vishay / Dale RN60D in most cases.
  • Main Output Transistors > On-Semi MJ Series Audio Transistors.
There is no doubt that it sounds far better then it did prior to the upgrade. However the very high mid and treble frequencies are now far too bright. So much so that I have to turn the amp off after a short listening period as my ears literally start to hurt.

Can anyone suggest what could be reversed or changed in the upgrade to remedy this?

It was suggested that I should change the power amplifier resistors back to carbon film, or perhaps another type, to see if this makes a difference. However this is something I am reluctant to do unless I was sure it was going to solve the issue.

I haven’t tried the phono stage yet as I don’t currently have a turntable therefore I am referring to CD’s only at this point.

All suggestions welcome.

Thank you.
 

gasolin

Member
try using som quality jumpers than the metal brackets that come standard
 

Hear Here

Active Member
Who did you get to do these mods and are they recognised by NAD as legitimate upgrades / improvements? I doubt it as NAD builds amps that, within their price range, offer exceptional value and are designed to thoroughly take advantage of available technology at the time of release.

NAD builds excellent kit, but it's done at a price where owners should accept that, as technology marches on change and new products are released, they should simply sell their "old" kit (prices of used NAD kit are always keen) and buy the latest offering. Don't spend cash on "upgrades" - just sell and buy better!

In earlier decades, I had never considered NAD as true hi-fi, but I must admit their Master Series is really up there with the best. I upgraded from M32 to M33 at very small cost as the M32 was sold for little less than I’d paid for it 3 or 4 years earlier and I asked for and was offered a 10% discount on a new M33. Now I have a first class amp using the best Class D technology (built by NAD under license with better components) costing well under £4K, powering a pair of £34K speakers. I could better the sound a little, but I suspect it'd cost me £30+K to do so.
 

Craig uk

Distinguished Member
Now I have a first class amp using the best Class D technology (built by NAD under license with better components) costing well under £4K, powering a pair of £34K speakers. I could better the sound a little, but I suspect it'd cost me £30+K to do so.
Sorry for the OT but 30k plus to better the M33? I suspect you’ve had very limited experience with amps in the 10-30k price range to make a statement like that.
 

Hear Here

Active Member
Sorry for the OT but 30k plus to better the M33? I suspect you’ve had very limited experience with amps in the 10-30k price range to make a statement like that.
OK - a challenge. Suggest any combination of streamer, DAC, pre and power and with room correction DSP and associated cables for that sort of money that will better the M33. I'd be very happy to audition what you come up with.

I have home auditioned a dozen amps in the £3-8K range (that's mostly just power amps) and I chose the earlier M32 as equal or better than all the rest. Adding the other features and (most importantly) bettering the M33 is a big ask, but I'm always up for improving the sound from my speakers. Thanks. Peter
 

Craig uk

Distinguished Member
OK - a challenge. Suggest any combination of streamer, DAC, pre and power and with room correction DSP and associated cables for that sort of money that will better the M33. I'd be very happy to audition what you come up with.

I have home auditioned a dozen amps in the £3-8K range (that's mostly just power amps) and I chose the earlier M32 as equal or better than all the rest. Adding the other features and (most importantly) bettering the M33 is a big ask, but I'm always up for improving the sound from my speakers. Thanks. Peter
To my ear there’s plenty of choice out there that outperforms the Nad if funds allow. If you’re looking for a starting point I would suggest the Vitus Audio SIA -25 mk2.


A streamer with room correction I would add the Linn Akurate DSM on the list.

 

gasolin

Member
Cambridge audio cxa 81 + the streamer Azur 851N ?

Or the edge a + the edge NQ streamer
 

Hear Here

Active Member
To my ear there’s plenty of choice out there that outperforms the Nad if funds allow. If you’re looking for a starting point I would suggest the Vitus Audio SIA -25 mk2.


A streamer with room correction I would add the Linn Akurate DSM on the list.

Well if I was spending £28,500 plus interconnects (say £1500 to be compatible with that expenditure) I'd expect a marginal improvement, but I doubt it would be significant. Rather than spend that amount on the front end, I'd always put more into speakers than electronics. Even with my speakers (£34K list), I would never consider spending £30K on 2 boxes of electronics (no CDP, no vinyl, so solely a streamer), though I would expect some small improvement in sound, although probably not (having tried Linn streamers in the past) on ease of use or flexibility. And would I buy an integrated amp without a proper volume control that was easy to operate? No. Try again at a price appropriate with £34K list price speakers - say £12K up front! Thanks. Peter
 
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Hear Here

Active Member
Or the Cambridge Edge A + the Edge NQ streamer
That's a combination I would like to audition in my system. At £11K (plus say £500 for compatible interconnects), I'd hope it may offer a marginal improvement over the £4K NAD. How big an improvement I'd like to judge myself, but the NAD may be a pretty pretty close match!

In fact the NQ streamer could be used with the W power amp, so making the combination an even more reasonable £9K plus cables. Thanks for the suggestion
 
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gasolin

Member
I could imagine Cambridge audio edge would go well with higher tier q acoustics
 

Kapkirk

Active Member
NAD 304 integrated amplifier - Sounds too bright after upgrade.

I recently had my NAD 304 amplifier upgraded with the components listed below.
  • Main Power Supply Capacitors > Nichicon LKS with increased capacitance.
  • Primary Capacitors in the Regulated Supply > Nichicon UFW
  • The remaining Regulated Supply Capacitors > Nichicon Muse with increased capacitance.
  • All other Capacitors in the Audio Circuits > Nichicon Muse, Fine Gold, Muse ES type.
  • Resistors were also upgraded in the Phono Amp, Pre Amp, Pre Amp Inputs, Tone Controls and Power Amp > Metal Film Vishay / Dale RN60D in most cases.
  • Main Output Transistors > On-Semi MJ Series Audio Transistors.
There is no doubt that it sounds far better then it did prior to the upgrade. However the very high mid and treble frequencies are now far too bright. So much so that I have to turn the amp off after a short listening period as my ears literally start to hurt.

Can anyone suggest what could be reversed or changed in the upgrade to remedy this?

It was suggested that I should change the power amplifier resistors back to carbon film, or perhaps another type, to see if this makes a difference. However this is something I am reluctant to do unless I was sure it was going to solve the issue.

I haven’t tried the phono stage yet as I don’t currently have a turntable therefore I am referring to CD’s only at this point.

All suggestions welcome.

Thank you.

First thing I must ask is the obvious, did you re-calibrate the quiescent current and DC offset after changing the Transistors?
Also changing the original specced components will have most probably caused this, I would suspect using modern metalized polypropylene capacitors and even use of metal film resistors (instead of carbon film) especially on the input stage can change the sound quite dramatically.
I wouldn't suspect any of the caps in the power supply or the new MJ series transistors which have probably improved things actually, the use of the Nichicon caps especially in the PS would definitely improve (or not degrade) the overall performance, but increasing their values can sometimes (surprisingly) have a negative effects on the sound even making the bass speed actually slower and less responsive.
Without studying the circuit diagram (and original component list to compare with the replacements) and doing live tests (by interchanging various components) it would be hard to nail it down quickly.
You may find the sound will settle down a little after the components have electrically burned in, even solder joints can take a while to settle down, you might find that a little strange but with audio it does happen. I would give it a few weeks of "power on" and see how it goes.

If I were doing a recon on this amp, the only things I would have changed would have been the power supply caps (using original values and brand where possible) and maybe the Power transistors for the newer better specced MJ's
 
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gasolin

Member
could there be a burn in periode like a new car ?
 

gasolin

Member
That's a combination I would like to audition in my system. At £11K (plus say £500 for compatible interconnects), I'd hope it may offer a marginal improvement over the £4K NAD. How big an improvement I'd like to judge myself, but the NAD may be a pretty pretty close match!

In fact the NQ streamer could be used with the W power amp, so making the combination an even more reasonable £9K plus cables. Thanks for the suggestion
Theres one set for sale in Denmark for just under £4600

 

Hear Here

Active Member
Theres one set for sale in Denmark for just under £4600

Thanks for the link, but that seems a new item and one may be clobbered for UK VAT and Duty on delivery. The Richer Sounds price is £5000, so perhaps that Danish one is less of a bargain. However there is a used one advertised in UK for £3500 - that's more like it!

I think I'll try to get a showroom demo next week (NQ + W) and if I'm impressed, perhaps arrange a home demo. Peter
 

gasolin

Member
Have you looked at the all in one unit Cambridge Audio Evo 150 (or 75 with half the power)

Cambridge Audio Evo 150 review

£2499
 
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