We got my pair of F4's together for the Burning Amp show, but the conditions weren't perfect for listening. The room was a too big, and I was exhausted and just happy that they were working.
Then I took them home and they are in a corner waiting to be rebuilt in a less slapdash way. At the end, the heroic crew ( I wasn't involved in the final at-show work- I was busy MC'ing while they slaved away..) ) that go it running just cut away stuff that wasn't needed for the demo, and the boards are floating in the air at the end of the MOSFET wires.. so I have a bit of rebuilding to do. I was certainly lucky to have Nelson standing a few feet away to offer sage advice to the pit crew.
We ran it with the two different preamps- SY's tube based one and Zen Mod's Pumpkin- both designed for the F4.
What struck me the most was the obvious difference in sound between the two. The F4 does as I had hoped- the preamp's characteristics come through transparently. I was very pleased with the sound, but it would be presumptuous to try and characterize it except to say that the tube amp was a little more delicate but certainly not whispy or anything, and the Pumpkin was really solid sounding but still with a ton of detail.
Keep in mind that we were using two F4's in balanced form (in fact at the moment Sy's pre ONLY works with balanced amps) so with my 95dB efficient speakers there was a real sensation of limitless power..
I am pretty darned sure that I will be very happy with them over the long term.
Now I have to make both preamps- as I don't know which one I will prefer in the long run.
Only Zen Mod's Pumpkin is available at the moment- I will absolutely get one based on what I heard..
I'm not saying that the great sound was due to the preamps- maybe the F4 makes everything sound good!
Then I took them home and they are in a corner waiting to be rebuilt in a less slapdash way. At the end, the heroic crew ( I wasn't involved in the final at-show work- I was busy MC'ing while they slaved away..) ) that go it running just cut away stuff that wasn't needed for the demo, and the boards are floating in the air at the end of the MOSFET wires.. so I have a bit of rebuilding to do. I was certainly lucky to have Nelson standing a few feet away to offer sage advice to the pit crew.
We ran it with the two different preamps- SY's tube based one and Zen Mod's Pumpkin- both designed for the F4.
What struck me the most was the obvious difference in sound between the two. The F4 does as I had hoped- the preamp's characteristics come through transparently. I was very pleased with the sound, but it would be presumptuous to try and characterize it except to say that the tube amp was a little more delicate but certainly not whispy or anything, and the Pumpkin was really solid sounding but still with a ton of detail.
Keep in mind that we were using two F4's in balanced form (in fact at the moment Sy's pre ONLY works with balanced amps) so with my 95dB efficient speakers there was a real sensation of limitless power..
I am pretty darned sure that I will be very happy with them over the long term.
Now I have to make both preamps- as I don't know which one I will prefer in the long run.
Only Zen Mod's Pumpkin is available at the moment- I will absolutely get one based on what I heard..
I'm not saying that the great sound was due to the preamps- maybe the F4 makes everything sound good!
transformer noise
Hi, I am new here and not very fluent in Forum tradition so please excuse me if I make a mistake at my first post...
I would like to build the 2xf4 (stereo balanced configuration) so I study this path of Forum. My first impresion is connected to the transformes, I need some advice.
I see the following links to the transformers dedicated to f4:
originally posted by Variac:
http://www.partsexpress.com/pe/show...tnumber=122-610
or: http://www.partsexpress.com/pe/show...tnumber=122-615
...snip...Or:
http://www.partsexpress.com/pe/show...tnumber=122-620
All trafos mentioned above does not have special isolation, there is an air and some foil only. They look exactly the same like the trafos I used in my Son Of Zen monoblocks - my problem is that I can hear the mechanical noise of 50 Hz or 100 Hz when the SOZ amplifiers are ON. I bought my trafos at a wrong dealer probably.
My question is what to do to cancel such a buzz. To buy new specially isolated or to flood my trafos in a special glue? Do you have an experience with transformators mentioned at Variac links? I am afraid to repeat the same buzzing trafo problem while building f4.
Best Regards
Andrzej
Hi, I am new here and not very fluent in Forum tradition so please excuse me if I make a mistake at my first post...
I would like to build the 2xf4 (stereo balanced configuration) so I study this path of Forum. My first impresion is connected to the transformes, I need some advice.
I see the following links to the transformers dedicated to f4:
originally posted by Variac:
http://www.partsexpress.com/pe/show...tnumber=122-610
or: http://www.partsexpress.com/pe/show...tnumber=122-615
...snip...Or:
http://www.partsexpress.com/pe/show...tnumber=122-620
All trafos mentioned above does not have special isolation, there is an air and some foil only. They look exactly the same like the trafos I used in my Son Of Zen monoblocks - my problem is that I can hear the mechanical noise of 50 Hz or 100 Hz when the SOZ amplifiers are ON. I bought my trafos at a wrong dealer probably.
My question is what to do to cancel such a buzz. To buy new specially isolated or to flood my trafos in a special glue? Do you have an experience with transformators mentioned at Variac links? I am afraid to repeat the same buzzing trafo problem while building f4.
Best Regards
Andrzej
Re: PCBs available, Studley
Originally posted by Studley
I have 2 of Peter's F4 PCBs and 2 PS PCBs available at cost, £25.
Hi Studley,
Do I understand well: your offer is good for four channel?
I would like to build stereo balanced configuration. Please confirm.
If positive – I am in.
Best Regards
Andrzej
Originally posted by Studley
I have 2 of Peter's F4 PCBs and 2 PS PCBs available at cost, £25.
Hi Studley,
Do I understand well: your offer is good for four channel?
I would like to build stereo balanced configuration. Please confirm.
If positive – I am in.
Best Regards
Andrzej
Re: Transformer noise
How big a transformer are you using? - 600 W per monoblock. See attached picture.
How hard are you loading it? - Power supply delivers +/-32V DC and acording to Mr. Nelson Pass SOZ power performance drawing I reach 300 W loading what results in max 16 W output power on 8 OHm speaker.
What brand are you using? - Brand is unknown, I bought transformers on the legendary electronic Sunday market known in Warsaw as Volumen. I hope now better transformers are available, I must go there some Sunday.
The transformer has to have at least twice the power rating of your amplifier - Yes of course - the power rating is approx 300 W, according to Mr. Pass advices. I remember at the beginning I had a problem with fuses delivering electricity to my flat - afterwards I applied thermistors on monoblock AC line.
I think my transformers have loose-fitting construction, what generates buzz; maybe the best idea is to flood them in synthetic resin in vacuum, but it is not available for me.
Kind Regards,
Andrzej
How big a transformer are you using? - 600 W per monoblock. See attached picture.
How hard are you loading it? - Power supply delivers +/-32V DC and acording to Mr. Nelson Pass SOZ power performance drawing I reach 300 W loading what results in max 16 W output power on 8 OHm speaker.
What brand are you using? - Brand is unknown, I bought transformers on the legendary electronic Sunday market known in Warsaw as Volumen. I hope now better transformers are available, I must go there some Sunday.
The transformer has to have at least twice the power rating of your amplifier - Yes of course - the power rating is approx 300 W, according to Mr. Pass advices. I remember at the beginning I had a problem with fuses delivering electricity to my flat - afterwards I applied thermistors on monoblock AC line.
I think my transformers have loose-fitting construction, what generates buzz; maybe the best idea is to flood them in synthetic resin in vacuum, but it is not available for me.
Kind Regards,
Andrzej
Attachments
Re: PCBs available, Studley
Hi, Studley,
Many thanks for reply. I'm so glad.
I will appreciate very much if you could reserve set of 2 of Peter's F4 PCBs and 2 PS PCBs for me - I am new on the board and I am "under moderation" now, so at the moment I can't use PM. I hope such quarantine period is short...
rgds
a.
Hi, Studley,
Many thanks for reply. I'm so glad.
I will appreciate very much if you could reserve set of 2 of Peter's F4 PCBs and 2 PS PCBs for me - I am new on the board and I am "under moderation" now, so at the moment I can't use PM. I hope such quarantine period is short...
rgds
a.
isolation technique
Hi Carpenter,
An isolation around transformer is very primitive, I know.
I had an idea to put isolation between all metal parts of housing, see attached foto. You can see an oak. This is because I afraid about distortions caused by rotary current which is potentially possible and unpredictible like thunderbolt. I remember I worked with people, who worked at projects of amplifiers, radio amplifiers and measuring devices. In one case, that was radio-amplifier, they discovered a strong rotary current generated by transformer at a closed loop created by metal parts, about 2 Amps. Such a current caused a very strong radio distortions. They cut a metal loop and phenomena dissapeared.
Best Regards,
a.
Hi Carpenter,
An isolation around transformer is very primitive, I know.
I had an idea to put isolation between all metal parts of housing, see attached foto. You can see an oak. This is because I afraid about distortions caused by rotary current which is potentially possible and unpredictible like thunderbolt. I remember I worked with people, who worked at projects of amplifiers, radio amplifiers and measuring devices. In one case, that was radio-amplifier, they discovered a strong rotary current generated by transformer at a closed loop created by metal parts, about 2 Amps. Such a current caused a very strong radio distortions. They cut a metal loop and phenomena dissapeared.
Best Regards,
a.
Attachments
Q1 and Q2
Hello,
I will appreciate very much for advice regarding Q1 and Q2 semis:
I see the lists of parts here, Peter and nycavsr2000 use 2SK170 and 2SJ74, but I do not see information about IDSS classification, there are 3 possibilities here: GR, BL and V. Please tell me which one fits the f4, in other words which one is the best for f4?
Best Regards
Andrzej
Hello,
I will appreciate very much for advice regarding Q1 and Q2 semis:
I see the lists of parts here, Peter and nycavsr2000 use 2SK170 and 2SJ74, but I do not see information about IDSS classification, there are 3 possibilities here: GR, BL and V. Please tell me which one fits the f4, in other words which one is the best for f4?
Best Regards
Andrzej
Re: Q1 and Q2
Dear all,
wait, wait, please, not everyone at a time, please...
I crawl along the diyAudio Forums > Top >Amplifiers >Pass Labs >F4 power amplifier;
now I am at Page 19 of 64, still nothing concrete, did I miss something, nobody knows, such a simple answer, a secret, BL, GR or V, or my English is so bad, nobody understands me, or what?..., my poor eyes are like...like Bart Simpson eyes...no Bart... Homer, I am Homer, yes, I should react like Homer saving nuclear-reactor and choose…one-two-three…BL,... ????
Keep on running (crawling),
Regards,
a.
Dear all,
wait, wait, please, not everyone at a time, please...
I crawl along the diyAudio Forums > Top >Amplifiers >Pass Labs >F4 power amplifier;
now I am at Page 19 of 64, still nothing concrete, did I miss something, nobody knows, such a simple answer, a secret, BL, GR or V, or my English is so bad, nobody understands me, or what?..., my poor eyes are like...like Bart Simpson eyes...no Bart... Homer, I am Homer, yes, I should react like Homer saving nuclear-reactor and choose…one-two-three…BL,... ????
Keep on running (crawling),
Regards,
a.
Re: Re: Q1 and Q2
Dear Zen Mod,
Many thanks for reply. -
As you see I have not to much practice with contemporary semiconductors. I am assembling parts for two balanced f4 and afraid to make mistake. In 1999 I made SOZ, one or two variations next, and I remember how difficult is to get ideal symmetry even in a such simple but very thermal solution. F4 has much more parts!
Kind Regards,
Andrzej
Zen Mod said:
Dear Zen Mod,
Many thanks for reply. -
As you see I have not to much practice with contemporary semiconductors. I am assembling parts for two balanced f4 and afraid to make mistake. In 1999 I made SOZ, one or two variations next, and I remember how difficult is to get ideal symmetry even in a such simple but very thermal solution. F4 has much more parts!
Kind Regards,
Andrzej
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