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Old 11th December 2002, 09:30 AM   #1
argo is offline argo  Estonia
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Default Power Follower 99 sound impressions?

I know some of the members of this board have built an Andrea Cioffoli's Power Follower 99 and I have recently put one together also. Mine runs from about 29 V rails and 2 A bias, uses IRFP240 instead IRFP150 and general low impedance capacitors not Elna Cerafines recommended by Ciuffoli.

My question is to those who have built or heard Power Follower 99 and compared to other amps perhaps about the sound characteristics of this amp.

After couple of evenings of listening this amp I have mixed feelings about itís sound. I need to decide, if I should go further with building this amp by replacing the caps to Cerafines (or similar) and transistors to IRFP150 to see any dramatic sound improvement or should I just drop it and recycle.
One more note: also a decent voltage gain stage is yet to come, I drive my Follower with OPA2134 single opamp circuit right now so this might have influenced total sound as well.

Any thoughts?


regards,
Argo
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Old 11th December 2002, 09:53 AM   #2
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No voltage gain is the reason that made me discard this project in favour of Aleph 30 (and Aleph X ).

Anyway I saw a interesting article on Rod Elliot's site, where a Power Follower by Pavel Macura is "integrated" with DoZ preamplifier. Since the 2 followers aren't that different you might try a similar arrangement, or switch to that project.

Cheers

Andypairo
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Old 11th December 2002, 10:09 AM   #3
argo is offline argo  Estonia
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Andypairo,

Actually to build a voltage gain stage is not a big issue for me right now. I have collected some schematics and good suggestions from other threads and I have the parts to build one. What I am more interested is if the sound of Andrea's Power Follower sound relay heavily on component quality and what are the overall sound characteristics of this amp. I can compare it only to my JHL class A amp now and they really differ from each other.

Argo
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Old 11th December 2002, 10:15 AM   #4
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Sorry for that I can't help.. no experience about it.

Cheers

Andrea
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Old 12th December 2002, 05:27 PM   #5
PMA is offline PMA  Europe
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Default preamp for power follower

Yes, the DoZ preamp gives a good sound impression. I have also made a preamp with OPA134 and I would prefer it, but the output voltage swing from OPA is limited to some +/-17V when supplied from +/-18V. You can find more circuits on my original page http://www.pha.inecnet.cz/macura/audiopage.html compared to Project83 on Rod Elliott's page. I would especially like to mention the project on http://www.pha.inecnet.cz/macura/pma1_en.html
Pavel Macura
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Old 12th December 2002, 05:39 PM   #6
JoeBob is offline JoeBob  Canada
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Changing the FETs to IRP150Ps probably wouldn't change much, I use IRFP044s in my Power Follower 99Cs. I use 3A with -33V. As for the parts reccomended by Ciuffoli, I wouldn't bother for the cerafines (except maybe the output caps). If you read any of his other articles, tube projects expecially, you'll notice that he says only NOS mullard tubes will sound good and other similar things, we all have our own opinions but I think any good quality cap can be used instead of the cerafines. As to the sound, I love mine, I can't compare them to an Aleph or Zen since I've never heard either. I would first of all replace the opamp. I run mine from a tube voltage gain stage and they sound great, I tried running them from an LM6172 preamp, and while it sounded alright, not anywhere near as good as it does now. I hope that helps, but I wouldn't give up yet, I really like the sound of mine, but then again mine's slightly different and we all have different tastes...
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Old 12th December 2002, 05:47 PM   #7
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I was wondering about the sound also... I thought about building a follower, but with a little twist- run two followers off of each side of a differential pair (such as the zen balanced line stage) and do away with the output cap. I had a schematic going one time that was completely direct coupled and used X feedback on the front end. I opted to build an Aleph X instead.
-NS
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Old 12th December 2002, 06:05 PM   #8
fezz is offline fezz  United Kingdom
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well, I DID make a power follower... but on plugging in everything appart from the resistors blew up - this was due to a faulty transformer that melted it's plastic coverings in about a second - i doubt even if i had fuses it would have helped

I am now making a zen amplifer instead with fuses
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Old 13th December 2002, 03:02 PM   #9
argo is offline argo  Estonia
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Pavel,
Nice to meet you here.
I looked to follow your follower project for quite some time but as it happened that I was left with those big IRFs lying around already (tried to build a Mini - A, a scaled down Aleph variant while ago but burnt my fingers with it, that is - it refused to let a decent sound out. Still wondering what was the cause, maybe bad input fets or something I donít know) I decided to try Andrea's project.
Do I read you correct that you prefer OPA134 based pre to DOZ preamp? I have looked at DOZpre as a candidate too but didnít like the need of those electrolytic output caps. +/-15V provided by OPA I think should be enough for my follower.

This other (New) follower of yours seems interesting too. Newer saw that in your site before. Thanks for the link. Might try that amp out as well someday.

NS
I saw somewhere in the net a page of one Italian guy who built Follower99 too. What I could read there, he tried to diff pair the followers too but couldnít tame DC offset in output and as whole amp got twice as big and dissipated twice as much also, the sound didnít improved a bit. At the end he abandoned that approach and returned to the original version with the output cap. I think the Aleph X is much safer way to go If you have decided to go with direct coupling and X- feedback.

JoeBob
Can you please describe the sound of your amp a bit. I know itís hard to do without any reference but in general or compared to some mass-market amp.
Why I so eagerly seeking for this description is, that I found Power Follower compared to JLH amp to be totally different. JLH amp is very clear, detailed and almost without any coloration of his own. It treats bad recordings as they should be treated - remorseless but it brings out all the little nuances of beauty of excellent recordings. Power Follewer instead lets the bad recordings sound quite good but doesnít do justice to the good recordings. It sweetens and smoothes out fine details and doesnít present the performance with such a reality and clarity as JHL amp does. I think it should perform better than that and there must be some kind of fault somewhere in the components, layout or setup.

fezz
Sorry to hear about your accident. Fuses are good thing to have. I blew out couple of electrolytic caps from my amp but saved the output devices because of fusing when I connected the power rails with wrong polarity through an oversight

Argo
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Old 13th December 2002, 03:28 PM   #10
JoeBob is offline JoeBob  Canada
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Wrong polarity huh? Well the same thing happened to me when I assembled mine, it blew a cap but once replaced it worked fine.

As for how mine sounds, well I was never good at describing these things but I'll try. First of all I use panasonic FC caps and not any fancy boutique parts. My amp does indeed sound "warm" but I could atribute that to the tube voltage gain stage, I don't know if that's actually due to the power follower, but that is something Ilike. On bad recordings I notice less imaging but other than that it does do a good job at making them sound better. But on good recordings I was really amazed, one of my favorite CDs, which sounded just like the rest, when I played it for the first time with my power follower I couldn't take it out of the player for a while. I just ordered a few vinyls and am in the process of building a RIAA preamp to see how it sounds with them. But what I did notice about my follower is that the midranges are better than anything I've heard before by a long shot, it made me realise what all the buzz about single-ended class-a MOSFETs was all about...
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