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First One - mosFET amplifier module

Seems like every new version is better than the last so it's worth waiting.
Here is a pic an active system I've built (one channel shown)
In an hot day with room temperature over 30 C, it gets pretty warm even with no load and sinks dimensions 30 X 16.5 cm (curly ends). I'm considering fans just to be on the safe side.

fo.jpg


The only problem I found is that with 1.4 is more troublesome setting the VAS current which should be done in box with covers almost closed. Also, I found that it changed after some time. This is not an issue with the 1.2 version. I hope this changes with the new version
 
Seems like every new version is better than the last so it's worth waiting.
Here is a pic an active system I've built (one channel shown)
In an hot day with room temperature over 30 C, it gets pretty warm even with no load and sinks dimensions 30 X 16.5 cm (curly ends). I'm considering fans just to be on the safe side.

fo.jpg


The only problem I found is that with 1.4 is more troublesome setting the VAS current which should be done in box with covers almost closed. Also, I found that it changed after some time. This is not an issue with the 1.2 version. I hope this changes with the new version

Nice build savvas! It would be interesting to see some inside pics also :)
 
Hi guys :wave2:

Lots of work lately, new FO module's front-end in R&D, as you all can see from THD plot in post #3914 this will position FO modules to pole position on the market.

Also new FO components launched to the market, FO music server, preamp DAC and power amp gain worldwide availability in autumn this year, online sales orders only.

Have all nice summer holidays. :)
More info about music server please.
 
20170621_220450.jpg

Because impedance of the 4 pol Mundorf is 1 ohm at 40 Hz I took them out and replaced them with 4 Spraque 100 uf 100 v. I shorted input and output. Also I added 4x 0,5 ohm Duelund parrallel resistors in series with output. Now the bass is much better and midrange a little softer. I think this is the best amp I ever owned.
 
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Because impedance of the 4 pol Mundorf is 1 ohm at 40 Hz I took them out and replaced them with 4 Spraque 100 uf 100 v. I shorted input and output. Also I added 4x 0,5 ohm Duelund parrallel resistors in series with output. Now the bass is much better and midrange a little softer. I think this is the best amp I ever owned.

Correct me if I'm wrong but it seems to me you are running XL module with ordinary PSU? How big torus and caps do you have for all that power :eek: ?

Just wandering, did you take out the Mundorf caps after listening to unmodified FO or you have done modification immediately?
 
Because impedance of the 4 pol Mundorf is 1 ohm at 40 Hz I took them out and replaced them with 4 Spraque 100 uf 100 v. I shorted input and output. Also I added 4x 0,5 ohm Duelund parrallel resistors in series with output. Now the bass is much better and midrange a little softer. I think this is the best amp I ever owned.

Great spirit, Erlend, thanks for posting; nice with modding experiences to an allready good construction. Somewhat of a praise, coming from You :)
 
Correct me if I'm wrong but it seems to me you are running XL module with ordinary PSU? How big torus and caps do you have for all that power :eek: ?

Just wandering, did you take out the Mundorf caps after listening to unmodified FO or you have done modification immediately?
Of course I and other listened to it before mods. And I have also built other First Ones (M) I have listened to First One in 4 different setups. Dynamics and bass power is better without the Mundorf. Earlier I have used about 200 Jensen 4 Pol in different projects. I ended up to give away about 100 of them.
 
Of course I and other listened to it before mods. And I have also built other First Ones (M) I have listened to First One in 4 different setups. Dynamics and bass power is better without the Mundorf. Earlier I have used about 200 Jensen 4 Pol in different projects. I ended up to give away about 100 of them.

Thanks for the interesting observation! Since you have that much of experience with different setups, could you say some more on what influence on on sound makes SMPS vs linear PSU, and did you find Dynamics and bass power better without Mundorf also with SMPS ?(if you have tried it)

:cheers:
 
I'm making BOM to decide which way to go with the build.
I have decided to go with SMPS so I made excel table to compare Hypex with Cresnet. It's attached.
Also I have made a list of possible add on cap bank for Cresnet. This capacitors are what is available on Banzai music which is reliable and convenient source for Europe. It is nothing definitive...
I would like to hear your thoughts on what would you choose.
:cheers:
 

Attachments

  • FO 1.4M BOM en.zip
    6.9 KB · Views: 78
  • FO CRESNET CAPS.jpg
    FO CRESNET CAPS.jpg
    157.5 KB · Views: 538
I'm making BOM to decide which way to go with the build.
I have decided to go with SMPS so I made excel table to compare Hypex with Cresnet. It's attached.
Also I have made a list of possible add on cap bank for Cresnet. This capacitors are what is available on Banzai music which is reliable and convenient source for Europe. It is nothing definitive...
I would like to hear your thoughts on what would you choose.
:cheers:

Think I read somewhere, that you don´t need softstart (at least with Cresnet SMPS)? (Not sure though, have to check up on it...)