Power Buffer Amplifiers like First Watt F4?

[virajsingh]

Hi All,

I would be grateful if the more informed HFV members could shed light on what are the other impedance converting amplifiers (power buffers) like First Watt F4.

Would it be an ideal match for the following high gain preamp ( FS: Excellent (and cheap) tube preamp with high gain - a partner for First Watt F4 ).

Also would F4 be an easy first DIY amp building project, and if yes where should I look for sourcing the parts to build it.

Cheers
Viraj Singh

 

[virajsingh]

Really surprised to find that no one is able to offer any advice on this genre of amplifiers...Do let me know as I am looking for something in the nature of a First Watt F4, its clone or something with similar design philosophy....

Thanks
Viraj Singh

 

[sachu888]

F4 is very old design.Genuine PCbs are not available anywhere.Keep an eye on DIy audio Swap meet section for PCbs.

Regards,
Sachin

 

[sachu888]

You may get a better response in DIY section.

Regards,
Sachin

 

[virajsingh]

Thanks Sachin,
Do you think that F5 Turbo V2 would be a good partner for this pre amp (FS: Excellent (and cheap) tube preamp with high gain - a partner for First Watt F4) or would the gain be too much.
Viraj Singh

F4 is very old design.Genuine PCbs are not available anywhere.Keep an eye on DIy audio Swap meet section for PCbs.

Regards,
Sachin

 

[omishra]

Hi All,

I would be grateful if the more informed HFV members could shed light on what are the other impedance converting amplifiers (power buffers) like First Watt F4.

Would it be an ideal match for the following high gain preamp ( FS: Excellent (and cheap) tube preamp with high gain - a partner for First Watt F4 ).

Also would F4 be an easy first DIY amp building project, and if yes where should I look for sourcing the parts to build it.

Cheers
Viraj Singh

F4 is only current amplifier means it will provide current for load and no voltage gain. Voltage is maintained as provided by preamp. Load current is not sucked from preamp but from PS of F4. But as per link, your preamp can operate any low gain power amp including F4, not necessarily F4 only. Basic F5 has low gain 15db and that could also be considered. F5 turbo has 22dB voltage gain. Compared with general gains of normal power amps, these are low gain amps.
refer quote from your link

As for the compatibility, I would suggest a lower sensitivy, lower gain power amps - say 2V input (or more) and gain as low as possible. This has plenty of gain. The output impedance is lowish (under 200 ohm) so it can drive anything, 10k power amp is just fine, the more the better.

As for the mods to lower the gain - this is of course possible but it's a matter of cost and convenience. First, you can do it via resistors or fixed attenuators (like Rothwell) but this isn't generally regarded as the best way to go. I haven't tried it though and despite reports that some systems react good I wouldn't recommend it without a proper trial. Second, you can exchange the output tube for something with less gain, like 6N6P, but this would mean rather serious work to provide different supply voltages and operational points for the chosen stage so basically this step wouldn't be for everyone. So, in short, I would prefer this to be taken by someone who has a power amp in need of a plenty of gain from the preamp so no further hassle involved.

Also that preamp does not specify what are output voltages and other ratings. It only say 2V above sensitivity for power amp. Still both version of F5 will do. If you consider basic F5 then user >24V supply rail. F5 turbo V2 with normal recommended 33V rail will also do.

 

[virajsingh]

Thanks Omishra.....I think you might have just put me on the road to my first DIY amp building project....Cheers

 

[captrajesh]

Read that thread. Congrats on your purchase. What was the landed cost? Curious to know how it fares against some Indian brands like Lyrita.

 

[virajsingh]

Read that thread. Congrats on your purchase. What was the landed cost? Curious to know how it fares against some Indian brands like Lyrita.

Thanks Rajesh,
I bought if for Pound 310 (about Rs 26K) and I think that will be the landed cost for me as an office colleage is bringing it in her cargo on transfer and I don't think there will be any custom duty that I should have to pay. I thought it was tremedous value for a pre with a seperate Power Supply Unit.

The pre is till in Belgrade (likely to come to India around middle April) and I will let you and the forum know how it compares to Lyrita, as I have only to go across to Viren's place in Delhifor comparing the two.

Best Regards
Viraj Singh

 

[captrajesh]

I will let you and the forum know how it compares to Lyrita, as I have only to go across to Viren's place in Delhifor comparing the two.

Looking forward.

 

[omishra]

Revisiting this thread again.
What happened? I was looking why its made so - a preamp with high voltage gain and power buffer amp to add current capability. On DiyA threads you might be knowing pumpkin preamp.

Pumpkin preamp - More Boring Making Thread - diyAudio
It can raise voltage to 40Vp-p . For any preamp this is killer spec.

 

[virajsingh]

Hi Omishra,

The preamp is not yet with me...I should think it should be arriving any time now. Have not yet decided what to do i.e. built a F4 (which could be difficult) or buy a F4 made by Firstwatt.... But I think I would just listen to it paired with bel canto / luxman power amps that a couple of friend of mine have.

Will keep the forum informed.

Viraj Singh

 

[GeorgeO]

Pre looks interesting.Good luck!

 

[virajsingh]

Hi All
The Nagard Acoustique preamp arrived earlier this week and was unboxed yesterday. Haven't had time to listen to it yet. The build quality is excellent and the preamp (minus the separate power supply unit) weighs 10.5 kgs.

I hope to test it out soon with bel canto and luxman power amps available with some friends. Will let you know what it does.

Cheers

 

[virajsingh]

Hi All,

The Nagard Acoustique Pre Amp had its first outing today when I took it to a friend's place to play it with his power amp. I have had this unit for 4-5 months now but since I do not have a power amp and none of my integrated amps can be made to work as a pure power amp the Nagard had been sitting at home.

Well today it was paired with the power amp section of a Luxman A-550 II used as a power amp. In my opinion the Amp was wonderful and it added weight to the music. The other components in the chain were an EAR ACUTE III CD Player with its own DAC as well as NAD M51 DAC. The speakers were Harbeth P3esrs and some really nice cables and interconnects made my Furutech and Harmonics and Harmonix.

My friend's primary system is EAR Acute III CDP > Luxman A 550 II integrated > Harbeth P3esr. With this same system configured as EAR Acute II CDP > Nagard Acoustique > Power Amp Section of Luxman A 550 A II > Harbeth P3esr, I noticed the same level of detail and realism that i find in his system. The sound was detailed and I think maybe a tad more controlled. The bass and the treble were well behaved and every thing sounded right. For the price (Rs 26K) it is a great tube pre and I am quite happy that i bought it.

Later I brought it home and hooked it between my source and Lyrita 845 SET playing though a Fostex special edition 8 inch full range driver based back loaded horn DIY speakers. It played fine but I need to try it out with a better source and cables. Lyrita SET integrated itself is a very musical amp and hence the Nagard was not shining in this configuration. I have to try it out with some other low gain power amps....but I think this is going to stay with me and maybe I will be someday get/make a first watt F4.

Viraj Singh