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25 watts Class A or 70 watts Class A/B ?

I understand these days there are many good examples of both Class A and Class A/B amps. To the point that a well designed Class A/B can beat a similar pedigree Class A amp. However my question is in particular related to these two amps:

1. First Watt F5 (Pass Labs)
2. Naim NAP 300

The speaker to be driven is a Tannoy dual concentric Turnberry SE. It is a 93 db sensitive 8 ohm load and in general considered to go well with both high powered and low powered amps.

F5 is a highly purist class A 25 watts design with a robust power supply. It is a push-pull design so it can generally drive difficult loads better than typical single ended first watt models (F3, F4 etc). I have heard the F5 on an Altec horn system and I loved its pure and direct sound.

Naim amps in general has always appealed to me, again because of their very direct presentation. Music has a certain excitement and bounce through them. The NAP 300 is one of their top models and I am sure it will be a very refined amp.

However I will only buy one. Both these amps must be having few fundamental differences in the way they present music considering they are coming from very different designers. Even the topology is different here.

The first question here is, can a 25 watts F5 drive the Tannoys well ? My room size is 200 sqft and I listen to music at reasonably medium to loud levels. I dont play very loud though. I listen to all kinds of music from Mozart to Metallica.

Qualitatively, sound per sound, how do these two amps compare ?
pani
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islandmandan
1,260 posts
 
Charles, from what little info I could find on the subject, the Turnberry's seem to benefit from a bit more power than that available from the typical 8-9 Wpc produced by SET 300B amps.

There was reference made to phase irregularities stemming from the Tulip Wave Guide/crossover interaction.

The Turnberry's seem to perform better with a bit more power, as a result.

Dan
charles1dad's avatar
charles1dad
10,250 posts
 
Thanks Dan. I was curious because Tannoy Westminster owners often report very good results with their 300b SET amplifiers. The Westminster may be an easier load for these amps{I'm guessing}.
Charles,
pani OP
1,219 posts
 
Atmasphere, I have never heard any of your amps before. I have only heard one OTL by Graaf and for some unknown reason I found it too coloured and bloated. However, I am trying to audition your amp here. Will report here if I get to hear them.

Charles1dad, I find it amusing that some westminister owners have complained repeatedly about their push-pull amps unable to control the bass of that speaker and then there are some who are ecstatic about them with puny SETs. I dont know that speaker well I guess.

Another amp that I may be considering is Ayon Crossfire III. It is a 30 watt SET built around AA62 tubes which are again derieved from 300B tubes. 30 watts of SET feels like a great proposal. Has anyone heard the Crossfire ?
charles1dad's avatar
charles1dad
10,250 posts
 
Pani,
The Ayon Crossfire from your description could be an ideal match with your Tannoy. I hope you're able to listen to it and the Atma-sphere OTL as well. I've heard the M 60 and MA-1 numerous times and they're very good amplifiers. I just personally prefer what a good SET uniquely offers. Horses for courses.Once you compare them, one or the other will move you more. It just depends on what type of sound you want.
Charles,
bo1972's avatar
bo1972
2,789 posts
 
Pass labs watts need to be X 5. when you go from A to B.

Naim and Pass Labs are so differently. Pass Labs is superior in depth and wide.

At shows with very extreme Naim stuff the stage was fully 2 dimensional. I had my music with me.

I played; light my fire from Jacintha. The cross flute in the beginning of the song was on the same line as her voice. In real it is about 3-4 metres behind her voice.

In my opinion depth and wide are essential parts for the absolute sound.

When you go back to a 2 dimensional stage you miss a lot of the exitement.

When I confronted the Naim people with these information. They did not know what to say.

An amp of 100 dollar also can give a 2 dimensional stage.

That is why I call 2 dimensional audio standard audio.

In 7 years of time I have done many comparisson between 2 and 3 dimensional sound.

All people prefered 3 dimensional sound far over 2 dimensional sound. Audio can sometimes be very simple and convincing.
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