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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
islandmandan
1,260 posts
 
Pani, from what little I delved into the design of your Turnberry's, and from listening to a pair of them at a friend's home, I gleaned they are a more difficult load than Monitor Gold's or HPD Tannoy drivers.

I am in the position where I just couldn't afford one of the top of the line Prestige speakers. Being in Singapore, a hotbed of vintage audio enthusiasts, you should have access to many vintage Tannoy drivers.

I know in recent years, prices for older Tannoy drivers has risen to near ridiculous levels, but where you are located, you may be able to find a bargain.

I spent a max of $4500 US to build my custom HPD's, which includes reconing the woofers with Hard Edge surrounds, custom crossovers using Mundorf SIO caps, Dueland reisitors, and Alpha Core inductors. The cabinets I had built of a total of 1 7/8" MDF @ 150 liters, and weigh 192lbs. bare weight.

They haven't disappointed in any way yet, no matter what amplification I've thrown at them. My point in all this is, especially in Singapore, having some custom built Tannoys should be very doable. I wish you luck.

Best regards,
Dan
charles1dad's avatar
charles1dad
10,250 posts
 
Dan,
Are the older Tannoys an easier load than the current models in general or is your speaker an isolated case?
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
1,224 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 ?
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