Simplistic NJFET RIAA - Page 505 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 30th September 2010, 09:26 AM   #5041
diyAudio Member
 
Join Date: Dec 2009
Location: Budapest
Hi All,

So my phono is getting better an better. I like it by replacing my stock one but sometimes especially daytime i would like more volume. I have a B1 buffer and after that a Zen variant (something like this
http://www.passdiy.com/pdf/retofzen.pdf
with 3.3uF in and out cap and some further mod ). Form B1 out i eliminated the 10uF cap.
I'm thiking of buying or building a preamp with gain. So the question is build or buy.
An old Parasound php750 would be enough or should i consider an aleph p or ... ?
With or w/o my B1 the sound seems to be similar for me. Maybe better w/o B1 but i need some attenuator.
On the other hand i know a ladder attenuator is a great alternative to adjust volume.

Any advice or example of your system would be appreciated.

Karesz
  Reply With Quote
Old 30th September 2010, 09:59 AM   #5042
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
If 2x gain is what needed, make Juma's BF862 pre. If you find it difficult or 6dB not enough, then BOZ is simple, 15dB, and good standard. My system has a sensitive valve amp, so no need. Buffer on a Zen is low gain chain.
  Reply With Quote
Old 30th September 2010, 11:10 AM   #5043
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi Salas,
what are the pros & cons of adding a +6dB pre-amp for the extra SPL, compared to increasing the RIAA gain by +6dB?
__________________
regards Andrew T.
  Reply With Quote
Old 30th September 2010, 11:16 AM   #5044
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Second stage would increase enough THD. I would buffer it and use an op amp if I wanted higher gain low THD drive directly to an amp. Although en for second stage would worsen a little due to op amp's Rin and feedback resistors. Example. With 0.6mV Eroica would give +7dB from his now phono for 850mVRMS low THD and buffered output to Zen, plus line level extra unity gain inputs with a switch. Don't know if x2.2 will be enough in his system or not, still. The LPs have higher velocities than 5cm used in nominal cart spec, but there are many quiet pressings too.
  Reply With Quote
Old 30th September 2010, 10:49 PM   #5045
diyAudio Member
 
The Space Egg Corp's Avatar
 
Join Date: Sep 2010
Location: London & Miami
Blog Entries: 13
Default Nice Board Merlin

Quote:
Originally Posted by merlin el mago View Post
One photo my Balanced Simplistic NJFET Phono RIAA just for fun:

Click the image to open in full size.

To finish only needs the 15nF RIAA caps.
Hi Felipe

Nice looking board.
How's the tuning going ?
Looks like you've got some fancy resistors in there.
I am wondering whether to splash some cash and do the same.
What are the 4 big space capsules that have landed in the middle ?
Thanks for the Thorens stuff again, haven't got the measurement yet.
Have also started looking at my Dual with a veiw to re-plinth and arm it.
I am afraid I might have got the diy tonearm bug from looking at the site too much !

Cheers Simon...
  Reply With Quote
Old 30th September 2010, 11:02 PM   #5046
diyAudio Member
 
taniknight's Avatar
 
Join Date: Oct 2009
Location: Mornington Peninsula, Victoria.
Hi everyone,

I haven't had a chance to swap the zener for a resistor yet Salas, so I can't comment on that mod yet.

I was wanting to know what the input sensitivity of the Simplistic pre is (in MM form)... more specifically, is it possible that I could clip it with a high output cart (5mV @ 5cm/1kHz) while playing a hot record?

Last night, while recording some records for comparison after tweaking the pre, I was pegging the meters on the audio interface when set to receive -10dBu. Salas Pre was going straight into the Apogee Ensemble. When on pro-level (+4dBu) all was good of course. I noticed some distorted sounds on a record that I hadn't played for some time... though this could be the material and I just haven't heard it so clearly before.

Thanks,
Tani.
  Reply With Quote
Old 30th September 2010, 11:16 PM   #5047
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Yours is the 41dB MM from the pdf yes? That should be 560mV RMS for MM 5mV. -10dbu=245mV RMS. Records can have +12dB modulations here and there. If its OK on +4dbu then its not self clipping. Check with an AC meter and a steady tone what mV you see. Maybe you got stronger Fets and more than 41dB gain even.
  Reply With Quote
Old 30th September 2010, 11:55 PM   #5048
diyAudio Member
 
taniknight's Avatar
 
Join Date: Oct 2009
Location: Mornington Peninsula, Victoria.
Yes, 41dB MM gain from the pdf. I only have a DMM of 'reasonable' quality, which I believe can only measure AC with any accuracy up to 400Hz or so. I can't use this frequency to check gain directly as it will be boosted by the RIAA, right? Can I simply check output mV at such a low frequency and have it be representative of the overall output?

I think I need a scope and some test records if I'm gonna take this mixer project seriously?
  Reply With Quote
Old 30th September 2010, 11:59 PM   #5049
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Use 1kHz if it can still catch it in the ballpark, its 0dB on Riaa but that would need an Lpad resistor divider down to 5mV from what higher source you got. Say 1:100 with 0.5V input. I would prefer a test record for your ease. It owes to peg -10dbu even if on spec though.
  Reply With Quote
Old 1st October 2010, 03:12 AM   #5050
diyAudio Member
 
The Space Egg Corp's Avatar
 
Join Date: Sep 2010
Location: London & Miami
Blog Entries: 13
Default Found These R-Cores After Searching For 3 Days.

Quote:
Originally Posted by le´flu View Post
Hi Salas,
question: how many VA for the transformer?
Found R-core after very long search.
Seems to be very hard to get item.
I would like to make pre all in one 19" x 340 case.
Looks like I might get away with it with R-core.
This one is only 30va but not to high to fit in 1u case.
I could use 2 to bump it up to 60va.

Cheers Peoples...Simon...
Attached Images
File Type: jpg 30va 15Vx2 81x68x37 0.5Kg 15.50euro Selectronic.fr.jpg (12.8 KB, 249 views)
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 04:24 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2