HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

My Topping E30 has pre amp and Dac modes. I usually use the former as it allows me to use the remote, but still keep it connected to the P20.

valvesRus wrote: ↑Sun May 16, 2021 1:43 am
Just remember that NVA power amps don't need an active pre amp because they have an extra gain stage to work with passive pre amps.

Using an active pre amp with most "other" power amps can give one better drive, but it's not 100% guaranteed.

One for Thomasz or savvypaul: is that true that NVA power amps have an extra gain stage?

My NVA A20 does not appear to have more gain than my Urei power amps.
I would have thought that an extra gain stage would have led to the NVA having considerably more gain.

Also, given Richard's philosophy of "less is more" it doesn't seem to make sense that he'd put an extra gain stage in his power amps, unless there was no other way round it.

Lindsayt wrote: ↑Sun May 16, 2021 9:20 am

valvesRus wrote: ↑Sun May 16, 2021 1:43 am
Just remember that NVA power amps don't need an active pre amp because they have an extra gain stage to work with passive pre amps.

Using an active pre amp with most "other" power amps can give one better drive, but it's not 100% guaranteed.

One for Thomasz or savvypaul: is that true that NVA power amps have an extra gain stage?

They have a gain stage that is designed for use with our passive preamps. I suspect your Urei power amps don't need an active pre-amp?

There is no "extra" gain stage in a nva power amp, just more gain than usual. Who would think Doc would have put in extra components when he believed that the best component was no component (where possible).

You make valid points Geoff however the OP clearly states he has bought nva power amps so there is enough gain. There is no one size fits all BUT why introduce more music robbing components (resistors, capacitors, transistors) when the same gain can be achieved with what we already have to work with - just change the amount of feedback for example.

The good Doc had it nailed in my opinion. As few components as possible - no active pre circuitry, no coupling capacitor in power amp, no output thiele network or zobel, no speaker level electrical filters. I share those beliefs so much I have moved heaven and earth to remove as many more things as possible in my gear. Everything I have removed so far has brought a smile to my face . CDP anologue stage 7 pole bessel filter gone - big grin after doing that. I managed to get rid of the speaker level high pass cap and padding resistor by means of a bit of jiggery pokery. Very rewarding ime.

I was forever being told that my diy Avondale amps wouldn't work with a passive pre. That turned out to be complete bollox because when I tried it I much preferred it ( and so did Alfi) even though there is less gain compared to nva amps. I was forever told that thiele and zobel networks on a power amp output were not audible. More complete bollox because when I removed them from the Avondale amp boards I was overjoyed. Same happened with removal of the input coupling cap.

All in my opinion / experience of course

valvesRus wrote: ↑Sun May 16, 2021 1:43 am

Just remember that NVA power amps don't need an active pre amp because they have an extra gain stage to work with passive pre amps.

It seems my wording has confused, I meant that the gain stage was "extra ", ie had more gain, not that there was another separate gain stage.

valvesRus wrote: ↑Sun May 16, 2021 11:23 am

valvesRus wrote: ↑Sun May 16, 2021 1:43 am

Just remember that NVA power amps don't need an active pre amp because they have an extra gain stage to work with passive pre amps.

It seems my wording has confused, I meant that the gain stage was "extra ", ie had more gain, not that there was another separate gain stage.

I think what you mean is that the sensitivity of NVA amps is appropriate to the use of passive pre-amps.

Not wishing to confuse I’ll keep this simple.
Whether or not you can use a passive pre-amp depends entirely on whether your source components are capable of driving your power amp properly.

The simplest passive pre-amp is an input selector and a volume control. If you use only one source, that is capable of driving your power amp properly, and it has a volume control you probably don’t need a pre-amp.

If you have multiple sources either with or without a volume control or you use a single source which does not have a volume control, but they/it can drive your power amp properly, you need a pre-amp. You can almost certainly use a passive pre-amp.

If you use multiple sources, with or without volume controls, and one or more of them can’t drive your amplifier properly, you need an active pre-amp. A phono stage is an active pre-amp or possibly an active pre-pre-amp.

Thanks everyone, very interesting and helpful. Excellent group.
I guess where I am coming from is, with a limited budget and a dac that can provide a level of control, am I better off spending money on power amps and a pre or power amps and upgraded cables? The consensus seems to be that you don’t need the pre.
Geoff.R.G, interesting what you say about output levels and sensitivity. My current system is using the RME dac into a Croft Micro pre amp with a pair of Quad II power amps which I had modified in the early 1990s by Doug Dunlop of Concordant fame. Sounds excellent but I have the RME output set to about 50% and the Croft volume set to around 33%.

One thing I've noticed is that if you have a volume control in the source and a volume control in your pre-amp or integrated amp - that it's generally better to have the volume in the source up high or open full tilt and the volume control later on in the chain to be the one that is curtailing the volume.

Generally. Up to a point. When I tried my EMT 950 with a transformer based (TVC) volume control (passive pre-amp) there was a volume setting on the EMT beyond which it sounded like the TVC was saturated - IE a an unpleasantly unnatural sound.

Lindsayt wrote: ↑Sun May 16, 2021 3:07 pm One thing I've noticed is that if you have a volume control in the source and a volume control in your pre-amp or integrated amp - that it's generally better to have the volume in the source up high or open full tilt and the volume control later on in the chain to be the one that is curtailing the volume.

+1
When I crank it up the volume on my phone is set to between 90-100% (fine adjustment range) with the volume on the P90SA at little over haf way.