How to match my tube pre-amp with various SS power amps

[pantera_rapida]

I have a few questions around matching my tube pre-amp with different power amps, and also about running my amps bridged.

Recently I purchased a (used) Primaluna Dialog Premium tube pre-amp. It works and sounds great, and I have it running through two NAD 2200 power amps (bridged). A bit later I purchased a set of used speakers which are 90dB and 4 ohm. A few people have mentioned I should not be using the 2200's bridged with that setup (but it's ok with 8 ohm speakers). I've run this configuration (PL-2200-speakers) for about 2 months now without issue. I never go past 94dB peak in the room with whatever I'm playing.

I've been looking around for another amp (or mono blocks) that could provide the same power/performance as the bridged 2200s. So far I've had no luck. Running the current setup with the 2200s I barely have to put the PL volume past 9pm, it's plenty loud and everything sounds excellent. The music sounds full, rich, big 3D soundstage, detail, etc.

But after A/Bing a few different stereo amps, even one with 400w @ 4 ohm, for all of them I have to put the volume closer to 11pm in order to match the same dB level for the music as I do with the 2200s. Why is that the case?

Are the 2200s bridged putting out the power differently than these amps to require the volume to be set so differently? Is this a gain (or impedance?) issue on the Primalina side? I've seen some amps, like the Parasound A21+, that have gain dials on the back, which you can turn up to 31dB. Would this amp be a better match then for the PL? It rather limits the types/number of amps I can use with the PL if that's the case. How would I know which amps are more qualified?

Lastly, if the 2200s work so well bridged with the speakers, should I just skip looking for an amp and leave them running as is? I was contemplating having them updated (caps, etc.) as they are still original (1987).

 

[312elements]

I have a few questions around matching my tube pre-amp with different power amps, and also about running my amps bridged.

Recently I purchased a (used) Primaluna Dialog Premium tube pre-amp. It works and sounds great, and I have it running through two NAD 2200 power amps (bridged). A bit later I purchased a set of used speakers which are 90dB and 4 ohm. A few people have mentioned I should not be using the 2200's bridged with that setup (but it's ok with 8 ohm speakers). I've run this configuration (PL-2200-speakers) for about 2 months now without issue. I never go past 94dB peak in the room with whatever I'm playing.

I've been looking around for another amp (or mono blocks) that could provide the same power/performance as the bridged 2200s. So far I've had no luck. Running the current setup with the 2200s I barely have to put the PL volume past 9pm, it's plenty loud and everything sounds excellent. The music sounds full, rich, big 3D soundstage, detail, etc.

But after A/Bing a few different stereo amps, even one with 400w @ 4 ohm, for all of them I have to put the volume closer to 11pm in order to match the same dB level for the music as I do with the 2200s. Why is that the case?

Are the 2200s bridged putting out the power differently than these amps to require the volume to be set so differently? Is this a gain (or impedance?) issue on the Primalina side? I've seen some amps, like the Parasound A21+, that have gain dials on the back, which you can turn up to 31dB. Would this amp be a better match then for the PL? It rather limits the types/number of amps I can use with the PL if that's the case. How would I know which amps are more qualified?

Lastly, if the 2200s work so well bridged with the speakers, should I just skip looking for an amp and leave them running as is? I was contemplating having them updated (caps, etc.) as they are still original (1987).

Your amp appears to have 32db of gain which is normal so it doesn’t surprise me that other amps require more juice from your preamp to get to the same level.

NAD 2200 Vintage Amplifier Review

This is a review and detailed measurements of a refurbished and upgraded NAD 2200 stereo amplifier. It was bought by a member, sent to QuirkAudio to be fully updated and then loaned to me. The work that Peter has done is exemplary. The inside looks brand new! I have repaired hundreds of...

www.audiosciencereview.com

 

[Blumlein 88]

In simple terms, your amps bridged have 6 db more gain. So for a given sound level you will turn down your preamp by 6db. If you ran one of them unbridged, you would end up raising the volume on your preamp. How this relates to other amps depends upon their gain which varies a bit between designs.

As 312elements said, bridged your amps have 32 db gain, unbridged they would have 26 db gain. Your amps are fine with loads of 2 ohms and larger unbridged, and 4 ohms and larger bridged. So that part is fine with your speakers. Your amps bridged might potentially damage your speakers if you play something as loud as it can go for long. Unbridged they might be safer. It will be far too loud for you either way by then. So probably not a problem.

So you likely wouldn't notice a difference in sound if you used one amp unbridged if you would like to turn the volume up a bit further. If it sounds fine as is, I don't see there is any problem. Some of the 4 ohm amps you tried probably had something like 26 db of gain requiring the volume higher. There is no advantage one way or the other generally in regards to the volume setting. If the volume isn't too touchy to set to your liking, no reason to worry about it.

If you are having no hum or other problems I'd skip having them updated. If updating them costs very much, probably more effective to put that money toward newer amps. You can certainly find amps with similar power and better specifications.

 

[pantera_rapida]

Thanks to you both, helps me understand things better. If I'm looking at vintage or newish amps, what should I look for? As I mentioned, the only amp I've seen so far that has the ability to control gain is the A21+, which goes up to 31dB at Max. I wondered if the PL pre-amp has quite low gain, I looked it up and it's 10dB.

I just tried an Aragon 4004 mkII with the PL, and looking up the specs now the Aragon has only 12dB gain? I had the volume close to 12pm to try matching the same sound levels as the NAD (which was around 9pm).

 

[312elements]

The distortion on the prima Luna likely increases as you adjust the volume so I get why you might have a preference here. The NAD c298 that I have has almost 29db of gain and can also be run mono which might increase the gain further, I’m not sure. It’s got no real sound signature of its own so it will showcase the prima Luna’s sound signature perfectly. I think it could be an amazing solution to the problem when you’re ready to move on from the 2200’s

 

[Blumlein 88]

I wanted to ask, do you think the pre amp sounds less good at higher volume? The volume being lower is generally no advantage. Most volume controls track better at higher volume. SNR can be better at higher volume settings though that is design dependent. I wouldn't base my decisions on the amp by thinking lower volume settings are superior. As long as you have some headroom it is fine.

 

[pantera_rapida]

In the case of the amps I tried none of them sounded great with the higher volume. Another issue I would guess is that the NAD bridged just put out more power and the sound is fuller. Although on paper the Aragon is 400w @ 4 ohms which I thought would have sounded the same.

 

[312elements]

In the case of the amps I tried none of them sounded great with the higher volume. Another issue I would guess is that the NAD bridged just put out more power and the sound is fuller. Although on paper the Aragon is 400w @ 4 ohms which I thought would have sounded the same.

Are you using lab in or normal in?

 

[Blumlein 88]

Well you basically need 42 db of gain then from source to power amp output. You have 32 db in the bridged amps and 10 db in the preamp. To match that you need amps with 32 db or more gain. More typical is 20-26 db in amps. Bridging adds 6 db usually so a bridgeable amp of 26 db should give you the result you want.

You'll probably want a power amp with a higher input impedance for this preamp. Something like 47 kohms or higher. Preferably 100 kohms. Many of the modern class D amps have 10 kohms to 20 kohms. Wyred4Sound has the ST500 mk II amp with 30.5 db gain, 100 kohm input impedance and enough power. It is an older IcePower design. I've had one maybe 15 years and it is still the amp on my main speakers. It might be a good match for your needs.

 

[pantera_rapida]

Are you using lab in or normal in?

Usually Normal, as I was of the impression this is a safer mode. I did use Lab once, I found the music did sound better.

 

[pantera_rapida]

Well you basically need 42 db of gain then from source to power amp output. You have 32 db in the bridged amps and 10 db in the preamp. To match that you need amps with 32 db or more gain. More typical is 20-26 db in amps. Bridging adds 6 db usually so a bridgeable amp of 26 db should give you the result you want.

You'll probably want a power amp with a higher input impedance for this preamp. Something like 47 kohms or higher. Preferably 100 kohms. Many of the modern class D amps have 10 kohms to 20 kohms. Wyred4Sound has the ST500 mk II amp with 30.5 db gain, 100 kohm input impedance and enough power. It is an older IcePower design. I've had one maybe 15 years and it is still the amp on my main speakers. It might be a good match for your needs.

Thanks. I have a better understanding of what's going on with the PL and power amps. Reminds me of the rabbit hole I had to go through for one of my turntables that had a cartridge that was less mV than my previous ones. I had to crank the volume on the (then Receiver) quite a bit and it still didn't sound good. Only after I found a phono pre-amp with more gain was I able to hear the turntable at it's best. Too bad there isn't a gain amp to help with situations between pre-amps and amps.

 

[312elements]

Thanks. I have a better understanding of what's going on with the PL and power amps. Reminds me of the rabbit hole I had to go through for one of my turntables that had a cartridge that was less mV than my previous ones. I had to crank the volume on the (then Receiver) quite a bit and it still didn't sound good. Only after I found a phono pre-amp with more gain was I able to hear the turntable at it's best. Too bad there isn't a gain amp to help with situations between pre-amps and amps.

Those exist, but tend to introduce noise if their own.

 

[Bob from Florida]

I looked up the specs on your preamp. You should not have any issues with input impedance of virtually power amp since the output impedance is 256 ohms. If you like your current power amps, don't worry about bridge mode speaker impedance issues. You make be try to solve a non-issue. Specs for your preamp below.

 

[RayDunzl]

I have a few questions around matching my tube pre-amp with different power amps

Something to consider for the power amp:

But...

 

[pantera_rapida]

The PL pre-amp only has RCA.

 

[Whiskey the Cat]

Just to muddy up the waters a little bit here. The Benchmark AHB2 power amp that I have has a three setting gain switch, and in their literature they say that ideally the user should select the lowest setting that does not cause the volume knob to run out of travel. The lowest gain setting will be compatible with the Benchmark DACs and preamps. However if you use a non-Benchmark power amp with a Benchmark DAC, then you can take the lid off the DAC and move jumpers to reduce the level being sent to the power amp. The object should be to have the volume knob above the 11.00 position when in use. If your preamp volume is set optimally to about 9.00 then (Benchmark would say) your power amp has too much gain, which is very common. They claim that doing this gives the optimal SNAID performance. There is an application paper on all this on the Benchmark website.

 

[pantera_rapida]

Just to muddy up the waters a little bit here. The Benchmark AHB2 power amp that I have has a three setting gain switch, and in their literature they say that ideally the user should select the lowest setting that does not cause the volume knob to run out of travel. The lowest gain setting will be compatible with the Benchmark DACs and preamps. However if you use a non-Benchmark power amp with a Benchmark DAC, then you can take the lid off the DAC and move jumpers to reduce the level being sent to the power amp. The object should be to have the volume knob above the 11.00 position when in use. If your preamp volume is set optimally to about 9.00 then (Benchmark would say) your power amp has too much gain, which is very common. They claim that doing this gives the optimal SNAID performance. There is an application paper on all this on the Benchmark website.

Yes, the 9am volume setting with the bridged NAD amps has been the exception. All the stereo amps I tried the volume was up around 11am.