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Search: Posts Made By: John Caswell
Forum: WD Amplifiers 5th December 2019, 01:27 PM
Replies: 5
Views: 99
Posted By John Caswell
Re: HT regulated PSU VI

Is there a need for regulated HV supply.
It would probably have to be an SS type.
Series or shunt ( which I don't like frankly)?
Voltage?
Dual for Pre/phono?
The cost of getting a PCB done is...
Forum: Problems 29th November 2019, 10:00 AM
Replies: 10
Views: 165
Posted By John Caswell
Re: KEL84 noise in left channel

Hi,
I would doubt it being a noisy capacitor more likely a noisy resistor or possibly a dirty PCB.
I would guess that from your description the nose is there all the time , so remove all inputs,...
Forum: Wanted 16th November 2019, 11:43 AM
Replies: 7
Views: 167
Posted By John Caswell
Re: Mullard Tropical Fish

I am a pedantic s*d:D
Bob bits in the post today/Monday

John
Forum: Wanted 15th November 2019, 12:40 PM
Replies: 7
Views: 167
Posted By John Caswell
Re: Mullard Tropical Fish

Hi Bob,
Yes got some, PM with address and I will stick them in the post to you.
I hate these colloquial terms for components - These are Mullard C280 capacitors 250Vdc rated.

John
Forum: WAD Problems 7th November 2019, 05:34 PM
Replies: 5
Views: 258
Posted By John Caswell
Re: WAD 300b kaput!

I have replied to this, but if there is anyone nearer to Adrian, please jump in

John
Forum: WAD Problems 10th October 2019, 06:06 PM
Replies: 7
Views: 397
Posted By John Caswell
Re: 300B PSE Problems

Hi Paul,
It may actually be the other way around, that the 300B goes faulty raising the "cathode" volts above what the capacitor can stand and bingo s/c capacitor.
Of course you don't suspect a...
Forum: WAD Problems 4th October 2019, 07:06 PM
Replies: 7
Views: 397
Posted By John Caswell
Re: 300B PSE Problems

Hi Paul,
Not sure why you are running your PSE with just one 300B as it would be working into an incorrect anode load.
Any way, the first thing I would check is the coupling capacitor to the grid...
Forum: WAD Problems 4th October 2019, 01:35 PM
Replies: 6
Views: 301
Posted By John Caswell
Re: WAD KiT 88 to WD KT88?

Hi Fred,
Yes of course it "can" be done but frankly not economical to do so, as there are many differences between the two.
I do not think that there is anything seriously wrong with your amp that...
Forum: General 30th September 2019, 02:55 PM
Replies: 10
Views: 840
Posted By John Caswell
Re: Hi-Fi Journeys

Re losing posts.
Simplest way is to write it in Pages or Word, save it somewhere then copy and paste into this forum - simples.

John
Forum: WD Amplifiers 26th September 2019, 09:56 AM
Replies: 22
Views: 1,015
Posted By John Caswell
Re: KEL84 from the recycling centre

Hi
Nicely done, looking at the PCB it seems to be the Mk1, the only difference being the PCB between 1&2 and also the provision of relay input switching, which you can add if you wish at a later...
Forum: WD Amplifiers 29th August 2019, 09:49 AM
Replies: 13
Views: 1,166
Posted By John Caswell
Re: WD MCT SUT question

Not surprising,
Andy Grove did the original designs for WAD and possibly WD under the pseudonym "Gary Devon" as I believe he was working for AN at the time, and as far as I am aware still does....
Forum: WD Amplifiers 28th August 2019, 11:51 PM
Replies: 7
Views: 564
Posted By John Caswell
Re: Zobel network on HD3S

Ian "Sharkey" wrote-
"I only recently learned that no load on output transformers is potentially harmful to them."
Not strictly true, damage may occur if you swap speaker leads or have o/c...
Forum: WD Amplifiers 28th August 2019, 07:27 PM
Replies: 7
Views: 564
Posted By John Caswell
Re: Zobel network on HD3S

I couldn't improve on Richard's comments if I tried - excellent description.
You don't really need a dummy load on the HD83 but if you have standard switched jack socket it is easy to arrange.
...
Forum: WD Amplifiers 21st August 2019, 02:50 PM
Replies: 13
Views: 1,166
Posted By John Caswell
Re: WD MCT SUT question

Hi Goomer et al,
You do not need to be so enthusiastic about twisting your wires together so tightly as you can easily break them without realising it.
After all they are all going to be inside a...
Forum: WD Amplifiers 18th August 2019, 04:44 PM
Replies: 13
Views: 1,166
Posted By John Caswell
Re: WD MCT SUT question

Hi Goomer,
Attached, I hope, are a couple of drawings that show how to wire up and switch between 10:1 and 20:1 for the SUT.
The toggle switch can either be 2 separate dpdt switches, one for each...
Forum: WD Amplifiers 18th August 2019, 11:17 AM
Replies: 13
Views: 1,166
Posted By John Caswell
Re: WD MCT SUT question

Hi Goomer,
Just doing some drawings, will post later in the day.

John
Forum: Amplifiers 17th August 2019, 05:23 PM
Replies: 4
Views: 679
Posted By John Caswell
Re: Triode/Ultra linear switch

Hi Graham,
As Alan says you do not need a 3way switch, however it does need to be close to the anode/screen grid connections of the valve and NOT on the front/back panel with long leads. That way...
Forum: For Sale 3rd August 2019, 05:35 PM
Replies: 0
Views: 366
Posted By John Caswell
ProAc D28 Response

My ProAc D28 Response in Ebony. 6 years old, usual but very slight fading to the veneers (solar film on windows). Smoke free, pet free, child free, audiophool free environment. Condition I rate as...
Forum: WD Amplifiers 27th July 2019, 03:44 PM
Replies: 3
Views: 567
Posted By John Caswell
Re: phono "output resistors"

Hi Stuart/Richard,
It is also there to isolate the C/f from the capacitive effects of the ongoing cable which if large can result in a rise in HF.
The sort of cable lengths we tend to use are quite...
Forum: WD Amplifiers 18th July 2019, 09:48 AM
Replies: 7
Views: 1,077
Posted By John Caswell
Re: WD Pre 4

About 10R, so will drive most things effortlessly.

John
Forum: WD Amplifiers 7th July 2019, 06:07 PM
Replies: 7
Views: 755
Posted By John Caswell
Re: More top end required

Whilst I agree somewhat with what Phil says, one of the main reasons for the phono II and III sounding a bit soft was the choice of output valve which often caused an HF "roll-off"
This was...
Forum: WD Amplifiers 6th July 2019, 09:12 PM
Replies: 7
Views: 755
Posted By John Caswell
Re: More top end required

First question, which phono stage please.

John
Forum: WAD General 5th July 2019, 02:13 PM
Replies: 9
Views: 793
Posted By John Caswell
Re: 5881 monoblocks

Gary,
You could always take it to someone thoroughly unprofessional, like me:D
I am in Finchampstead
PM if interested.

John
Forum: WAD General 4th July 2019, 10:02 AM
Replies: 9
Views: 793
Posted By John Caswell
Re: 5881 monoblocks

Hi Gary,
Well certainly all the three 5881 variations were never ever done as mono blocks so this must be a home-brew by someone. Regret I cannot throw any further light on them.

John
Forum: WD Amplifiers 2nd July 2019, 12:53 PM
Replies: 6
Views: 642
Posted By John Caswell
Re: KEL34 problems

Hi Roy/Richard,
Yes can do if required.
PM for address etc.

John
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