Search found 138 matches

by karatestu
Fri Feb 03, 2023 6:06 pm
Forum: Beginners
Topic: NFB capacitor
Replies: 26
Views: 12490

Re: NFB capacitor

ed wrote: Fri Feb 03, 2023 2:43 pm
Nick wrote: Fri Feb 03, 2023 1:18 pm No, not certain. What is the current circuit?
I don't know. I have old circuits for AP10, AP30,AP70,A60,A70. I'm not sure of the provenance of any of them, it was a long time ago.
Perhaps Steve or Stu could comment on the ltp on their boards.
Yes there definitely is a LTP.
by karatestu
Fri Feb 03, 2023 8:26 am
Forum: Beginners
Topic: NFB capacitor
Replies: 26
Views: 12490

Re: NFB capacitor

Thanks Nick NVA famously don't have input coupling caps but mine do as removed them from my source components . I have red wima mks2 3.3uf in currently for input coupling not sure they are available in 47uf. My film caps are evox rifa mmk 47uf 63v and bloody massive. I might look for wima and if not...
by karatestu
Thu Feb 02, 2023 6:44 pm
Forum: Beginners
Topic: NFB capacitor
Replies: 26
Views: 12490

NFB capacitor

Good evening, Been thinking about feedback caps in solid state power amplifiers. I only have experience of Naim, Avondale and NVA amplifiers. The feedback arrangement is similar in all of them. I know they have to be a certain value ie 47uf and above. Naim used a polarised electrolytic. Avondale rec...
by karatestu
Mon Jan 16, 2023 8:41 pm
Forum: Beginners
Topic: Split rail from two positive regulators
Replies: 17
Views: 13196

Re: Split rail from two positive regulators

Yes it is a clone of the stage line. I've got about 8 phono stages including the nva , personally I prefer the naim over the nva . .you can buy regulators for it , but I just use two 350va transformers ,2 33,000uf caps per rail and 1 bridge Fair enough. Must be bigger than Coke cans those caps :D I...
by karatestu
Mon Jan 16, 2023 3:41 pm
Forum: Beginners
Topic: Split rail from two positive regulators
Replies: 17
Views: 13196

Re: Split rail from two positive regulators

DQ - is your phono stage based on the Naim Stageline or similar. They use two +24V rails as standard. Naim put the regs in the power supply at the end of one metre of wire. I would suggest that the regulator would be better close to the load if you were going to do it.
by karatestu
Mon Jan 16, 2023 3:36 pm
Forum: Beginners
Topic: Split rail from two positive regulators
Replies: 17
Views: 13196

Re: Split rail from two positive regulators

The NVA phono stage comes as standard with regulators. They are very simple . LM317 & 337 with the necessary resistors and 0.1uf film caps on input and output ( from memory). I remember RD saying that the stage did benefit from regulators but very simple ones. I am trying something which is quit...
by karatestu
Mon Jan 16, 2023 2:34 pm
Forum: Beginners
Topic: Split rail from two positive regulators
Replies: 17
Views: 13196

Re: Split rail from two positive regulators

I suppose this would work with two secondaries that are not centre tapped ?
by karatestu
Mon Jan 16, 2023 9:44 am
Forum: Beginners
Topic: Split rail from two positive regulators
Replies: 17
Views: 13196

Re: Split rail from two positive regulators

Many thanks. Will be doing it in the next few weeks hopefully.

Stu
by karatestu
Mon Jan 16, 2023 9:19 am
Forum: Beginners
Topic: Split rail from two positive regulators
Replies: 17
Views: 13196

Re: Split rail from two positive regulators

As always the first place to start is with the documentation of the part: In general, the best type of capacitors to use is solid tantalum. Solid tantalum capacitors have low impedance even at high frequencies. Depending upon capacitor construction, it takes about 25 μF in aluminum electrolytic to ...
by karatestu
Mon Jan 16, 2023 6:17 am
Forum: Beginners
Topic: Split rail from two positive regulators
Replies: 17
Views: 13196

Re: Split rail from two positive regulators

There was some talk on pfm that using two positive regulators with LM317 in this way can be better than using the LM337 because the 317 regulates better. I wouldn't know about that. The nva phono uses 317 and 337 in the traditional way. It has small film caps on the output of the regs which I though...
by karatestu
Mon Jan 16, 2023 6:06 am
Forum: Beginners
Topic: Split rail from two positive regulators
Replies: 17
Views: 13196

Re: Split rail from two positive regulators

Two entirely separate transformer secondaries to their own bridge rectifier and cap. Positive on cap to vin on regulator. Negative on cap to 0v. That then gives you two entirely separate 18v supplies call them a and b. Connect vout of supply b to 0v of supply a. Vout of supply a is +18v. Point wher...
by karatestu
Sun Jan 15, 2023 7:21 pm
Forum: Beginners
Topic: Split rail from two positive regulators
Replies: 17
Views: 13196

Split rail from two positive regulators

Hello. Trying to get my little brain round something and need a little help. I have four Avondale Audio TPR4 regulators sitting around doing nowt. There are two separate positive voltage regulators on each board. Its basically a tracking pre regulator with voltage reference and capacitance multiplie...
by karatestu
Sun Nov 13, 2022 7:31 pm
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 178093

Re: DIY Transistor Amp Using NVA Boards

Cressy Snr wrote: Sun Nov 13, 2022 4:30 pm
Ray P wrote: Sun Nov 13, 2022 3:31 pm It doesn't look as though you're using the feet that were in the box I gave you - the speakers were much more stable when fitted.
That job is on the list for next week. I need to get some shorter M6 bolts than the ones I have. :)
Hacksaw
by karatestu
Mon Nov 07, 2022 5:37 am
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 178093

Re: DIY Transistor Amp Using NVA Boards

Cressy Snr wrote: Sun Nov 06, 2022 10:08 pm NVA based SS amp is now a permanent fixture:
2891FE90-764B-4323-88E4-480681E83264.jpeg
With 85dB efficient speakers, a solid-state amp of decent power is the obvious choice.
Looks easy on the eye Steve. I expect it's kind to the ears too. :D
by karatestu
Mon Oct 24, 2022 7:31 am
Forum: Assorted Stuff
Topic: Owston meet, Doncaster, 22&23 Oct 22
Replies: 171
Views: 40255

Re: Owston meet, Doncaster, 22&23 Oct 22

I must agree with something Paul B said earlier. At Owston in the past, at least half of the music played is not to my taste at all, and makes evaluating the kit a problem. Before anyone else says, I dare say what I do like is not to everyone's taste either. :lol: I certainly concur there Phil but ...