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   Home » Analog Playback» The last phonocorrector: “End of Life" Phonostage (311 posts, 15 pages)
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03-30-2010 Post does not mapped to Knowledge Tree
Wojtek
Pinckney (MI), United States
Posts 178
Joined on 09-01-2005

Post #: 76
Post ID: 13243
Reply to: 13242
Hmmm,I suspect
fiogf49gjkf0d
It was an agent of Oswald Mill in mover's disguise. He didn't take PSU because it's not tube rectified. On a serious note I do hope that you'll be able to find it somehow burried in the stuff ,or it will miraculously appear on your door step.
Regards, W
04-07-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 77
Post ID: 13263
Reply to: 13237
The "End of Life Phonostage” is back.
fiogf49gjkf0d
Ok, I did find the phonostage. It was sitting in one of the drawers. I do see a rational for me to put in there- to make sure that it would not be shacked during remodeling but, kill me, I do not remember I put it in there. Anyhow, it is back and it is good – that is all that matters.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-19-2010 Post does not mapped to Knowledge Tree
AlexBerger
Israel, Beer Sheva
Posts 20
Joined on 04-19-2010

Post #: 78
Post ID: 13308
Reply to: 13263
My "End of Live" vesrion.
fiogf49gjkf0d
Hello Romy,

I just have build the postage used your "End of Live"  scheme and Altec step-up transformers.

http://picasaweb.google.com/alex.berger73/Phonostage#

I have original EAR.
After of 100 hours of working, the new Phonostage  sounds more dynamic, transparent with much better separation.
One problem is 100Hz hum. I did hitter supply filter with too weak ripple filtration: C-L-C (13200uF-3mH-6600uF).
Now I going to rebuild  hitter supply.
Is any difference in sound of semiconductor stabilization filtration, C-L-C-L-C or L-C-L-C filtration?

Best Regards,
Alexander.
04-19-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 79
Post ID: 13310
Reply to: 13308
The 100Hz hum?
fiogf49gjkf0d

 AlexBerger wrote:
Hello Romy,

I just have build the postage used your "End of Live"  scheme and Altec step-up transformers.

http://picasaweb.google.com/alex.berger73/Phonostage#

I have original EAR.
After of 100 hours of working, the new Phonostage  sounds more dynamic, transparent with much better separation.
One problem is 100Hz hum. I did hitter supply filter with too weak ripple filtration: C-L-C (13200uF-3mH-6600uF).
Now I going to rebuild  hitter supply.
Is any difference in sound of semiconductor stabilization filtration, C-L-C-L-C or L-C-L-C filtration.

Alexander, are you sure that it is 100Hz hum but not 120Hz hum? Even I do not like and tend do not use CLC supply for filaments but your hum most likely is NOT due you your PS. The 13200uF-3mH-6600uF is enough to drive the ripples low and kill the hum.

It is VERY difficult to debug any devise “over the phone” in search of hum. Hum is most likely some kind of ground loop and you need to find it yourself. Pay extra attention to the wiring diagram of the old Altec step-up transformers. I have some of them (Altec and EV) and they are in my view need to use extra shielding and they are very difficult to make them to be quit.

What you need to do for sake of simplicity is take a wire of 2 feet long and begin to short different sections of your new pnonocorrector grounds. Soon on later you will find the location that after they were shorted minimize the hum. This will give you an answer where the hum comes from. I would do it separately for the pnonocorrector and then what I find the absolutely silent configuration, only then I would put the transformer to the game.

Also, considering the proximity of the air caps to the filaments I would VERY strongly advise to use twisted pair for filaments. The twisted pair is very singly but it is VERY effective as it is self-shielding. You can detect if the hum come from air caps by disconnecting them. Also use the “disconnecting trick” to see if the problem comes from the filaments. When you turn off the corrector off then it will be still a second or two operational. You will be able to hear how the hum will change in the moment of disconnection. Remember, what you disconnect the B+ still there and the tube is still hot but there is no filament voltage…

Rgs, The Cat

PS: I am sorry, I juts realized that you are in Israel and you might have 50Hz power line. Then sure you will have 100Hz hum not 120Hz as we have here in US.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-19-2010 Post does not mapped to Knowledge Tree
AlexBerger
Israel, Beer Sheva
Posts 20
Joined on 04-19-2010

Post #: 80
Post ID: 13311
Reply to: 13310
Hum “disconnecting trick”
fiogf49gjkf0d
Romy,
I tried before to cover transformers by foil sheet, it didn't help.
Now I try “disconnecting trick”. The hum was disappeared after phonostage had switched off, while music continued to play.
The filament ripple is 32m Volt (5% from DC level). It can be caused the hum?

Thank for your help,
Alexander.

04-19-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 81
Post ID: 13315
Reply to: 13311
Right grounding configuration for PS, corrector and transformer assembly.
fiogf49gjkf0d
Alex,

From what you report it looks like it might be the filaments. The 32mV is a bit high for filament ripple, I usually prefer it to be 5mV but 32mV shell not have hum.  Do not bring the filaments directly as you did but make it running by tool loops and ONLY by twisted pairs. Disconnect the transformer. Short the input grid and measure the noise at input. You shall have sub 3mV. If you have no noise at outputs then the problem is in the grounds between your corrector and your transformer – a very common problem. The problem that you are experiencing is nominal – you need to find right grounding configuration for your PS, corrector and transformer assembly.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-20-2010 Post does not mapped to Knowledge Tree
AlexBerger
Israel, Beer Sheva
Posts 20
Joined on 04-19-2010

Post #: 82
Post ID: 13320
Reply to: 13315
The hum is drooped significantly!
fiogf49gjkf0d
Romy,

I try to remove the step-up transformers & short the input grid, the hum has gone.
Than, I did next changes:
1. Twisted wire from input RCA to step-up transformers. Connect transformers input & output ground directly (not thought ground bus as before).
2. Connect filament minus to the power supply ground directly (not with 100 ohm as before).
3. Connect wall outlet ground to the chassis thought 50 ohm, like in original EAR (not with 22 ohm as before).
4. Connect  chassis to the RCA output ground point (not to the power supply ground point as before).

The result, the hum is drooped significantly to the acceptably level.
Actually, right channel no hum at all, the left channel has minor hum.
Maybe because, left channel transformer is 10 cm nearer to power supply than right channel transformer?

I going to put  shielding aluminum plate between power supply and RIAA board. It will help?

Another question: what is the necessary accuracy of second  tube grid resistor (2M). It's used in RIAA equalization?

Thank you again,
Alexander.
04-20-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 83
Post ID: 13321
Reply to: 13320
Generally the phonocorrector has very low noise.
fiogf49gjkf0d
Ok, you are getting somewhere. I am not sure why I used the 100R, 50R and 22R resistors. It is good idea in some cased to list the potential of some circuits but it need to be used ONLY what it necessary. Do not forget that in your case you have 5 chassis: PS, 2 correctors and two transformers. Connection of the two transformers chassis is tricky. In some case you want to connect them together and THEN to connected them to corrector/s. You need to run a few experiments how to do it in your configuration. To connect grounds a few inches here or there might make a significant difference. It looks like one of your channels is fine, now you need to fine tweak the grounding on the second one. The 2Meg resistor is necessary for the second side of the corrector.

Generally the phonocorrector has very low noise. I have it with 27dB gain transformer and 109dB sensitive playback. Running the playback wide open at max gain I have no noise. At max gains I have a very minor “breathing” of my LF arrays but no auditable noise, rather some LF pressure in the room but no sound. I presume that it is sub 20 noise – which is fine by me since I use only class A amps and the ULF harmonics do not drain the PS one my amplification. Mind you that with this phonocorrector and playback at max gain the volume is absolutely insane and I never play it at this volume. My normal listening level is good 30dB below, so whatever “noise” I have at max volume level is absolutely not auditable at listing levels.  That all is very nice as the phonocorrector has exposed filtering caps that shall be susceptible to pick up some AC dirt from air. For whatever reason they do not and my corrector has no noise even without box. BTW, the polarity of the air caps might be a factor. Make the AC go enter the air cap chassis and exit from the air cap insert. This way you will have the chassis of the air cap to do some extra self-shielding.

The trick with the air caps is to set them to the correct value. When they are connected then the values are changed. So, you need very accurately up-solder the air caps from the circuit, to measure then with trusted pF meter and then put the wares back. Alternatively you can have high precession RTA and you can run ant-RAAI or a test dist sweep and adjusting the air caps you can get horizontal response. I used both methods and they both give identical result. The only problem with this corrector is that I did not fixate the air caps. They are as they are and I do not shape the corrector. They do hold the values but I guess if I violently shake the correctors then they will not – the same as the tuners. I decided do not glue the air caps. Sometime in future I will make the perm air caps from pure cupper plates – with 100pF and 330pF it will not be too difficult….

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-20-2010 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,570
Joined on 10-12-2006

Post #: 84
Post ID: 13323
Reply to: 13321
DIY Air-Caps?
fiogf49gjkf0d
Romy, I hope you will give us a show-and-tell when you do this.

Best regards,
Paul S
04-23-2010 Post does not mapped to Knowledge Tree
AlexBerger
Israel, Beer Sheva
Posts 20
Joined on 04-19-2010

Post #: 85
Post ID: 13339
Reply to: 13321
Capacitors
fiogf49gjkf0d
Romy,

I used second tube grid resistor, 1.8Meg Holco. (I couldn't find 2 Meg chip and good quality resistor: Dell RN60D or Holco or even Caddock MK-132.)
But I felt the deep bus was cut. I tried 1.8Meg Holco & Riken 220K in serial. The deep bus increased.
I just have ordered 2Meg expensive Caddock TF020F in www.partsconnexion.com . I think it will be better that two serial resister. Another option was AN tantal, but it sounds unnatural for my ears.


Does capacitors combination 100pF and 330pF sound more correct that original values 110pF and 330pF?

What is break-in time for new phonostage?

Alex.
05-14-2010 Post does not mapped to Knowledge Tree
AlexBerger
Israel, Beer Sheva
Posts 20
Joined on 04-19-2010

Post #: 86
Post ID: 13502
Reply to: 13320
Hum again.
fiogf49gjkf0d
Romy,

I have rebuilt my phonostage (the pictures after update are added to Picasa):

1. Fixed filament.  Now a ripple about 1mV (unmeasured by my Fluke).
   The filter is: C-L-C-L-C 30000uf-3mH-30000uf-3mH-30000uf.
   I put two 3mH chokes & Nichicon capacitors, instead of chip no name capacitors.
2. Put 2M OHm resistor incited of 1.8M + 220K.
3. Put shielding aluminum plate between power supply and RIAA board.
4. Retuning air capacitors.

But hum is steel in the same level as is was before.
I try analyze the problem.
Maybe it caused by antenna effect of strait wires between step up transformer and first stage?
Should I put twisted pair wire instead?

Interesting that sound is changed notable after the rebuild. The sound is lusher and more natural, without metallic ringing coloration in piano as before. 
Maybe the chip no name capacitors in the filament damaged sound?  

Alexander.  
05-14-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 87
Post ID: 13505
Reply to: 13502
Hm, again....
fiogf49gjkf0d
Alex, I think that there is VERY high probability that your hum is from transformer-correctors interfaces.  Get rid the transformer, change the loading resistor accordingly and use the corrector with high outpour cartridge, let say over 3mV. If you will not have any hum in MM configuration then it will be it – find different ways to connect transformer. Do not forgets that you hum is not signal noise and not PS noise but ground noise. Keep bridging the different points on ground and you will find what you pick up the loop. I wish it would be easier way to help you but I think there is no way to be more useful in this virtual communication.

The lusher sound you report is very good. In my experience this it has the lushiest sound of ANY phonostage I have heard out there. It is super lush but very dynamic – a very infrequent combination - at least with my transformer.

Regarding the metallic ringing coloration in piano – it is more complicated.  Some pianos do have this effect. Some piano has some harpsichordish way to sound – it is not necessary bad, with some music and with some playing it is very-very good and your phonostage shall not smooth it. Most of the phonostages do opposite – they play LP zippy and hard – the audio people call it “quality”. So, my point is that phonostage shall do some moderation and play the things in right way…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
02-23-2011 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 609
Joined on 01-07-2006

Post #: 88
Post ID: 15615
Reply to: 5862
Tribute MC iron
fiogf49gjkf0d
Hi all,
I'm slowly progressing with my assault on the pussyfied 834.
I'm looking around for an interesting step up.
I've happily eliminated SU-1 (I'd rather daydream about a night with
Monica Belluci instead of those ugly steel boxes), said fuck off to S&B
and their TX-103 (fuck their stupid dance: we sell-we don't sell-we sell at 3x price),
kissed good bye to the stupidly overpriced telephone-line bandwith vintage
MC's and find myself left with either Dave Slagle's or Tribute.
Dave's prices are steep and I don't need a nice box.
So Tribute is left with his toroid amo cores.
Does anyone have any experience with Pieter's MC's esp. with 834?

Cheers,
N-set




Cheers,
Jarek
STACORE
02-27-2011 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 609
Joined on 01-07-2006

Post #: 89
Post ID: 15648
Reply to: 15615
Changing loads
fiogf49gjkf0d
Romy (and the followers) how do you change loads when using 834 with different carts?
I was thinking of low thermal EMF Hg reed relays (the idea I've copied from Romy)
A sample part is e.g. Coto 3520-12-911 .
If they prove ok, a volume control switch based on them may be worth a try.

Cheers,
N-set




Cheers,
Jarek
STACORE
02-27-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 90
Post ID: 15650
Reply to: 15648
I do not do adjustable loading.
fiogf49gjkf0d
I have coved this subject in past. I was not able to find a solution how to add resistors to change loading and how to make it to be switched that would not degrade sound. So, my own phonocorrector has no adjustable loading. If I need to do it I would re-solder the loading resistor. I have no plans to do it as I picked my 3 default cartridges that they all work fine ageist my default load. Theoretically I can add loading to the primary of my Expressive SU2 transformer, where the RCA inputs from tonearm are but I do not see a need to do it. I must admit that if I play other cartridges then loading would be useful but I am not in business of experimenting with  analog option and what I have a good solution then I lock the setting and juts use the opportunity do not do anything with it.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
02-28-2011 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 609
Joined on 01-07-2006

Post #: 91
Post ID: 15662
Reply to: 15650
Sound degradation vs proper loading
fiogf49gjkf0d
I see. This is a very fortunate situation.
Unfortunately my TSD15 wants to see a high load of 200R,
hence the question.
Low EMF shielded reed relays
seem to be especially designed
for switching uV signals (unlike gas filled Au over Au/Pd ones I've found),
but I've been so far unable to talk to anyone having experience with them.


Cheers,
N-set



Cheers,
Jarek
STACORE
02-28-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 92
Post ID: 15663
Reply to: 15662
Loading on primary?
fiogf49gjkf0d
Yes, I guess I would sing the different songs if I need to load them differently. In fact Mi might need but I juts refuse to acknowledge it. Nevertheless I am not planning to compromise my phonostage by different loading. BTW, did you try to load the primary of your transformer instead? Purely hypothetical - what is to solder a very small 1/16W resistor on the cartridge side? The lording on primary and secondary shall have different impact. I know that AN Kondo transformers have selectable loading for primary and secondary and their own cartridges are usually loaded to ultra low impedance…. so I wonder….


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
02-28-2011 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 609
Joined on 01-07-2006

Post #: 93
Post ID: 15665
Reply to: 15663
Anticipating the needs
fiogf49gjkf0d
I haven't played with the loadings yet, as I'm still in the deep woods of the assembly
and a hunt for an intelligent SUT. But the primary loading scares me
with it's super sensitivity to the resistor quality, value, etc.
Anyway, I'm somehow optimistic that in the XXIst century we are able
to reliably switch uV signals such that any sound degradation is
orders of magnitude lower than the benefits of the right load. Perhaps I'm stupid...



Cheers,
Jarek
STACORE
04-06-2011 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 609
Joined on 01-07-2006

Post #: 94
Post ID: 15938
Reply to: 7480
CCS heating?
fiogf49gjkf0d
Good people,
Has anybody tried CCS heating of the tubes here?
That idea +/- makes sense to me (more with DHT though)
and wanted to try it, but perhaps somebody has already
been there? I'm thinking of 3 individual LT337 past the last
reservouar caps, CCS'ing
each tube/stage (heaters in series of course within each tube).

Cheers,
N-set



Cheers,
Jarek
STACORE
08-01-2011 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 609
Joined on 01-07-2006

Post #: 95
Post ID: 16754
Reply to: 7480
2nd stage bias mystery
fiogf49gjkf0d
 Romy the Cat wrote:

EAR834PT.jpg

This is a technical post.

I've made some progress on my assault on the above version of EAR 834. After hard (mostly because of my idiocy)

labouring through the soldering, I've creeped to the level where I can make some static tests.

I must say the biasing of the second stage is a pure mystery for me: +270 on the rail, 330k load, -0.9V

theoretically cuts the tube out according to the curves or I'm completely out after all the solder fumes?

I do get +270-273V on the B+ rail (accross the first 150u fileter cap), I have -0.92V on

the divider (R13 -R14 junction) but tyhe plate is anywhere from 110V to 140V depending on a tube.

For the experiments I use some cheap Chinese

(one I've already sent to hell) and one TAD specimen. The tubes are CCS heated at the ideal 150mA and in fact

they want to stabilize at somewhat lower heater voltages from 10.8V to 11.8V instead of 12.6V, but perhaps

that's a Chinese crap.

Perhaps -0.9V quoted above is a mistake? Theoreticaly the

47k-10k divider gives 1.1V from 6.3V (I have a 12.6V heated so I adjusted the bias to the published 0.9V).

Anybody able to clarify/help? The 1st stage is +/- ok at 100-110V but the bias is rather -0.8V then -1V.

Thanks in advance.

PS I also do get quite some wideband noise at the output (no 100HZ though)...will investigate, perhaps

the VR's (I've put them close to the 2nd & 3rd stages).





Cheers,
Jarek
STACORE
08-01-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 96
Post ID: 16759
Reply to: 16754
It is true but it negligible.
fiogf49gjkf0d
Yes, you are right, the voltage divider from 6.3V across 47K and 10K resistors shall give not 0.9V but 1.1V. However, the numbers that are in circuit are not something that I saw in my dreams but the actual numbers that I measured. I might presume that at the time I measured it I did not run the phonostage from my AC stable PP2000 but from wall and the voltage was lower and I did not have 6.3V but perhaps 6.1V or something like this.  All those numbers are perfectly acceptable and with 1V basis the 12AX7 is not near to be closed up. I do not know what curves you looked at but 1V is fine bias for this tube and with 140-150V on plate it is perfectly fine operational point. Thanks for spotting the .2 difference but I think it is in given case negligible.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-02-2011 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 609
Joined on 01-07-2006

Post #: 97
Post ID: 16762
Reply to: 16759
V2 biasing continued
fiogf49gjkf0d
 Romy the Cat wrote:
Yes, you are right, the voltage divider from 6.3V across 47K and 10K resistors shall give not 0.9V but 1.1V. However, the numbers that are in circuit are not something that I saw in my dreams but the actual numbers that I measured. I might presume that at the time I measured it I did not run the phonostage from my AC stable PP2000 but from wall and the voltage was lower and I did not have 6.3V but perhaps 6.1V or something like this.  All those numbers are perfectly acceptable and with 1V basis the 12AX7 is not near to be closed up. I do not know what curves you looked at but 1V is fine bias for this tube and with 140-150V on plate it is perfectly fine operational point. Thanks for spotting the .2 difference but I think it is in given case negligible.


Sorry Romy, I did not want to sound nitpicking. I'm rather trying to understand if my copy works +/- properly.
Will try to lower the bias to 1.1V to see how it reacts.

About the curves: I'm probably too stupid to get those small signal tubes, but 150V@-1V should give 1.1mA so the 330K load  
would drop 363V...and the B+ is only 270??? In my case, with -0.92 I get 110-140V@the plate so 0.4-0.5mA (my filaments are
unintentionally starved though at 11.something volts).



Cheers,
Jarek
STACORE
08-03-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 98
Post ID: 16778
Reply to: 16762
Works +/- properly
fiogf49gjkf0d
 N-set wrote:
Sorry Romy, I did not want to sound nitpicking. I'm rather trying to understand if my copy works +/- properly.
  
I do not see you nitpicking, you do the right things and I wools do the very same if I was at your place. 1V at the 12AX7 bias is more or less where it has to be. My phonostage is an inspiration from Tim de Paravicini’s EAR but it was a few modifications made. The one that you are dealing is that I wanted the cathode of the second stage to sit on ground, aka Melquiades.
 
Anyow, it is not difficult to find out if your copy works +/- properly.  If you have right plate voltage and the tube has the expected gain then the stage works fine. I do not remember now but I believe in closed loop the corrector shall give 55dB or something like this, it is not difficult to calculate. Did you use air caps or cheated and used mica?
 
The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-03-2011 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 609
Joined on 01-07-2006

Post #: 99
Post ID: 16782
Reply to: 16778
To cheat or not to (ccs)heat
fiogf49gjkf0d
 Romy the Cat wrote:

Anyow, it is not difficult to find out if your copy works +/- properly.  If you have right plate voltage and the tube has the expected gain then the stage works fine. I do not remember now but I believe in closed loop the corrector shall give 55dB or something like this, it is not difficult to calculate. Did you use air caps or cheated and used mica?
 
The Cat


Thanks for the reply.
That's the problem--I don't seem to have the right voltage--too low, even as low as 110V, depending on a tube
(at the moment shitty Chinese).
I've ordered resistors to change the divider to 1.1V to see how it behaves. I did not measure the gain still,
listening to white noise...

I've modyfied your design a bit adding CCS heating. Don't ask me why...an intellectuall capriccio,
which costed a significant layout complication and to some extent unfortunately compromise.
There is no fucking cheating Stick out tongue Will post some pics soon.



Cheers,
Jarek
STACORE
08-30-2011 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 609
Joined on 01-07-2006

Post #: 100
Post ID: 16887
Reply to: 16782
My assault
fiogf49gjkf0d
After going through the anal pains of the Image Gallery upload (it is so
huge now that my browser slows down 10000x times loading it and it ocasionally kicks
my router out of this world; can we do something about it?), here are some pics
of my assault on the Pussyfied EAR 834. This is basically a blatant copy
of Romy's unit, with some minor additions and a bit different layout.
It's not finished. It's soldered and statically tested (OP points etc),
but I'm endlessly waiting for the SUT's from Tribute so no idea when I'll start listeting.
I also want to go through the PSU with a scope to see how it performs.

Here is the PS block  top view:

PSU_Top.JPG

The power supply transfromers are separated by a grounded copper plane.
The transformers are form a Polish supplier Telto, custom wound to my specs
(windings on separate legs, double screened with copper foil)
Not recommended! They become warm and the HV one buzzez a bit...despite being
3x overseized. The trannies as well as all the open chokes are surrounded by a copper
band to supress some of the garbage they emitt.
Here is the bottom view:

PSU_Bottom.JPG

Everything, following actually Romy's idea, is mounted on a alu plate using industrial silicone
and screws. Nothing vibrates and the feeling is of being acoustically quite damped. There are
commercial RFI filters +varistor per each tranny, a varistor + gas arrester at the input,
NTC on HV, time relais on HV, two pilots, and an hour meter bypassed with 0.22u cap.
Paul will recognize his saturated shellac trick Wink (still not everywhere done--have to scope the unit first).

Here is the top view of the signal box:

Signal_Top.JPG

The fron and the rear panels are covered with a plastic-protected 0.3mm copper foil and so will
be the top and the bottom covers. This should create a +/- "hermetical"
electrostatic screening.
The main changes wrt Romy are 1) a CCS heating has been implemented with
a big pain as to the soldering/layout (the regulators are below the
middle alu bar) It was my intellectuall capricio which costed me endless hours of work, hope it all
burns in hell after I die; 2) The VR's are close to the tubes; I somehow feel better having the regulation elements
close to the regulated ones, so that the pickup on the umbilical have some chance to be cleaned by VR's too.
3) The 1.5mm thick plate (protected with some plastic spay) is suspended on homemade
suspensions (I saw prices of commercial ones and said "thank you"):

Susupension.JPG

4) The last filtering stategs of the heating/bias is also on the plate. Here is the general view
of the mess I've created:

TheMess.JPG

If you don't like my layout, you are not alone, I don't like it either Smile
I've soldered directly to the rotor of the air caps. One was easy as it has silver coated blades,
the other one has alu blades so a special flux and a 200W iron were needed. Let's see how it
works with time (corrosion etc)..
 I have been trying to find a method
to solder to the plate directly, but failed, resorting to bent and solder coated 1.5x10 mmcopper strips, bolted
to the plate and protected with the shellac (there are 2 of them--at the input and between 2nd & 3rd stages).
All that resulted in resistors being quite lifted above the ground plane. Very much not recommended!
This is one of the mass terminals:
DetailsIII.JPG

And some more boring details:

DetailsI.JPG

DetailsII.JPG

The wireing is cardas (let it burn in hell for being so infinitely stiff and such a pain to solder!!!)
The thin ones are the tonearm 33ga wires to let the caps move. The air caps, the coupling caps,
the heater caps, and the signal tube sockets are mechanically insulated with sorbothane
(it actually looses some chemicals which melt a bit the copper plastic cover, damn sorbothane).

The PSU and the signal blocks are connected by a homemade umbilical with 15.5ga cardas
and some new production Polish military-style connectors. Very much not recommended,
it's better to pay the $$ for the real amphenol rather than those mediocre copies.

Umbilical.JPG



The fron and the back view of both units (without the covers):

Backs.JPG

Fronts.JPG

After I recover from the horrors of the image gallery, I'll try to post the actual schematics of what I've done.
There are some minor changes mostly because of my mistakes in PSU design, and a
 lottery of the PSU trannie outputs with a desire to maintain the real choke operation.

The next step is to try to listen all that mess and see if the months of hard work were worth it...We'll see.




Cheers,
Jarek
STACORE
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