Various questions about DIY line preamp

Giovanni1968

Giovanni1968

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Joined 2016
flickr.com/photos/giovanniaprea/
Hi all,

as of now my setup is an Audio Research SP9 preamp and a twin KT88 power amp, there is a turntable which sees no use (because of space constants), plan is to build the F4 to power the JBL L220 and put the tubes on the side, the F4 should do nice with the hi gain of the SP9 but I was wondering how difficult would be to build a preamp.

For the F4 am gonna ask a dear and skilled friend to build as that's too much for a first timer with limited experience and instruments like me but was wondering about an unbalanced line preamp to match the F4 (ideally I would delegate the AR SP9 and KT88 to a secondary stereo to use my older JBL4311b), how difficult would it be, how expensive and if it would have the about 20db gain to drive the F4.

Any input welcome


Grazie


Giovanni
 
Ciao Mark,

well, it depends on the cost, I mean, if it ends up costing what I could get off selling my SP9 (which I don't know if I'd eventually then sell) it would be viable so, yes, cost is a primary concern along with quality which I expect to be an upgrade off the Audio Research.

Maybe my idea that a pre has less expensive stuff than a power amp inside the case is wrong but thinking of a smaller case, smaller transformer, smaller filtering even tho there is switches, potentiometer and connects is wrong but I am trying to figure it out as to have an idea and then eventually try and to build something myself which adds to the experience.

Grazie
 
Hello Mark,

I am by no means so instructed about the matter to the point to know which configuration would do better, my romantic me likes tubes for their heritage but my pragmatic me likes an heterogenous mix along source to speakers.

As I have an F4 in the build by the end of summer (this is very busy time for me so it will have to be delayed but both boards and MOSFETs are here already and soon either transformers or case will follow) I'd like a line only stage to match it, no need for whistles and lights, I will either feed it with a DAC (I have a very basic one) or my old CD player, the turntable can either work with the AR SP9 but even there I am looking at an EAR834p clone but phono is not a priority, the cleanest the signal the better.

Grazie Mark, have a nice day
 
You might take a look at the circuit in the thread at: Pass HPA-1, what do we know?

Although intended primarily as a world class headphone amp, some people use it as a line amp. It makes a very good one, and its equipped with a line output for that purpose. Stereophile still rates that HPA as in some ways having unrivaled sound quality. Its the HPA they seem to use for most HP reviews. Would certainly use it as line amp myself.
 
Markw4 said:
Stereophile still rates that HPA as in some ways having unrivaled sound quality.
Click to expand...
Per their subjective listening impression which doesn't mean anything to others who weren't there in that room on that day (Stereophile technical editor John Atkinson's standard reply to objective listening test).
 
Hello Marc, ciao Even...

would the HPA-1 be an easy (relatively) build? I don't need a headphone amp, I also regret getting the DAC with such an amp, I am one of those who prefers minimalism, I like photography and, to say one, stabilised lenses, whistles and bells don't do it for me, they actually distract off the experience and the more there is the more prone to break...

Gain wise and "sound" wise would it match the FW F4?

Buona giornata
 
A match to an F4? My own very personal opinion is that HPA-1 probably clearly superior to F4 in terms of sound quality. Thus I don't think it would hurt the sound of F4; more likely it would give a better overall sound. Of course what sound someone likes is a personal opinion. You will have to decide for yourself what is right for you.

That said, Marcel is right that sometimes all it takes is a passive attenuator volume control. There is no gain available in that case, but if no gain is needed then why not go with passive?
 
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Giovanni1968 said:
Hello Marc, ciao Even...

would the HPA-1 be an easy (relatively) build? I don't need a headphone amp, I also regret getting the DAC with such an amp, I am one of those who prefers minimalism, I like photography and, to say one, stabilised lenses, whistles and bells don't do it for me, they actually distract off the experience and the more there is the more prone to break...

Gain wise and "sound" wise would it match the FW F4?

Buona giornata
Click to expand...
Try page 2 of the following link on preamp for F4. https://www.firstwatt.com/pdf/prod_f4_man.pdf

Also, beware of internet poster who praise sound quality of audio electronics. Most of them don't do objective comparison so their conclusions don't provide useful info.
 
F4 looks to be a buffer without gain. So, a high input impedance, and a low output impedance. That makes it suitable to go between a high-ish output-voltage preamp and a loudspeaker. IMHO too bad it uses electrolytic coupling caps in the audio path, but if one likes the sound of the caps then its not a problem.
 
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