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-   -   1 Meg ganged log pot (https://www.vintage-radio.net/forum/showthread.php?t=159522)

stumted2 5th Sep 2019 6:05 pm

1 Meg ganged log pot
 
Hi all,

Does any kind soul have any idea where I may purchase a 1 Meg log ganged pot? its for a Pye black box.
Or is it possible to modify the amp using a normal single pot?

your help would be very much appreciated.

Cheers,
Ted.

John10b 5th Sep 2019 6:48 pm

Re: 1 Meg ganged log pot
 
Blore Edwards ( Blore-Ed.com) may be able to help.
Cheers
John

stumted2 5th Sep 2019 7:13 pm

Re: 1 Meg ganged log pot
 
Hi John,

Many thanks for your message, I will try to contact them tomorrow, but I would guess they may be rather expensive.

Cheers,
Ted.

stumted2 5th Sep 2019 7:53 pm

Re: 1 Meg ganged log pot
 
Hi all,

I do have a 500k ganged log pot, could I possibly use this, and would this have any adverse effect on the amp/sound?

Sorry to sound a bit dim, but all help and advice would be very much appreciated.

Cheers,
Ted.

stumted2 5th Sep 2019 9:02 pm

Re: 1 Meg ganged log pot
 
Hi all,

I forgot to state that this pot is a volume control.

Cheers,
Ted.

Herald1360 5th Sep 2019 9:23 pm

Re: 1 Meg ganged log pot
 
1 Attachment(s)
If this is the Black Box with the dual gang pot set up as a loudness control (boost bass / cut treble at low volume) you could forget about this aspect and just use a single pot as a conventional volume control.


Take R4 direct to wiper of single pot and leave the series RC disconnected.

stumted2 5th Sep 2019 10:29 pm

Re: 1 Meg ganged log pot
 
Hi Herald 1360,

Many, many thanks for your very much appreciated kind help, it is the black box with the dual gang pot, and I will as you suggest, replace this with a single pot with the modifications you have suggested.

Many thanks once again for your kind help, all my kindest regards,

Ted.

Michael Maurice 6th Sep 2019 12:42 am

Re: 1 Meg ganged log pot
 
Blore-Edwards are not expensive,

Cricklewood electronics also have them

https://www.cricklewoodelectronics.com/DLG1M0E.html

stumted2 6th Sep 2019 8:55 am

Re: 1 Meg ganged log pot
 
Hi Michael,

Many thanks for you message and kind help, yes you are correct, Cricklewood are good value, and I will try to contact Blore-Edwards for a price of pots.

I will most likely as Herald 1360 recommended, just fit a single pot.

Many thanks once again for your very much appreciated kind help, all my kindest regards,
Ted.

Edward Huggins 6th Sep 2019 9:35 am

Re: 1 Meg ganged log pot
 
Although not defined in these Posts, this looks to be the BB PCL83 version. By fitting a single volume pot, you will loose the original Loudness feature, but you can compensate for this with the concentric Bass and Treble tone controls.

stumted2 6th Sep 2019 2:56 pm

Re: 1 Meg ganged log pot
 
Hi Edward,

Many thanks for your message and much appreciated kind help.

The model is a BBH and the valve line up is ECC83, EL42, and EZ41. The tone pot is a single gang tone control. (which has little affect on the tone)

I have changed all relevant caps, replaced bad valve connectors in the valve bases, (very time consuming) and now all is ok except for the vol. pot which despite several shots of switch cleaner, after a short time, becomes very noisy again, this is why I thought it may be the best bet to replace it.

The only problem so far is the new pot shaft is a little too short, so I'm now trying to find a pot shaft extender, but no luck so far.

I have tried Will at Bowood, but he doesn't stock these.

Once again many thanks for your kind help, all my kindest regards,
Ted.

AC/HL 6th Sep 2019 3:37 pm

Re: 1 Meg ganged log pot
 
Is it the type that can be dismantled? It may respond to a deep clean.

Edward Huggins 6th Sep 2019 4:55 pm

Re: 1 Meg ganged log pot
 
Quote:

Originally Posted by stumted2 (Post 1174088)
Hi Edward,

Many thanks for your message and much appreciated kind help.

The model is a BBH and the valve line up is ECC83, EL42, and EZ41. The tone pot is a single gang tone control. (which has little affect on the tone)

Ted.

Ah, seeing the circuit again I should have sussed the model better! Thank you.
Have you also changed the components associated with the Tone Control as it should give quite a good range of "Cut"? Also removing the "Loudness" feature, will also have a sonic effect on the Tone Control at certain volume levels. I would try to re-build the ganged Pot if I were you. Be aware that this amplifier is rather intolerant of the most well-intentioned circuit alterations.

John10b 6th Sep 2019 6:49 pm

Re: 1 Meg ganged log pot
 
I would definitely check the price of the Blore Edward pot, it may be more expensive but it will be close to original spec as I understand it.
Just to give you some idea of price, I bought two 1 meg log pots with switch for about £8 each. They donít seem to have a minimum order.
Cheers
John

stumted2 6th Sep 2019 6:58 pm

Re: 1 Meg ganged log pot
 
Hi Bill,

Many thanks for your kind message and help, but the ganged pot will be a real tussle to get into, with uncertain outcome, so I would very much prefer to replace it with a new one.


Hi Edward,

Having wrestled with this player over many hours, (I have had this to pieces three times now) I am seeking the easiest and quickest way to complete this project, so I may well run the risk of circuit alteration in order to finally complete this player.

Your thoughts and kind advice are very much appreciated.

All my very best and kindest regards,
Ted.

stumted2 6th Sep 2019 7:11 pm

Re: 1 Meg ganged log pot
 
Hi John,

Sorry for my late reply, I was just replying to Bill and Edwards message. Many thanks for your much appreciated kind help, and armed with this info, I may well give Blore Edward a call, it's just that I have spent so much time and effort on this project, I am running out of enthusiasm. (I am very old now)

Many thanks once again for all your kind help and words.

All my very best and kindest regards,
Ted.

stumted2 6th Sep 2019 7:25 pm

Re: 1 Meg ganged log pot
 
Hi all,

Just a thought, I do have a brand new high quality 500k ganged log pot, could I use this, or would it be totally unsuitable?

All members thoughts and advice would be very, very much appreciated.

All my kindest regards,
Ted

Herald1360 7th Sep 2019 12:09 am

Re: 1 Meg ganged log pot
 
Used as is a 500k pot will introduce some bass cut. If you can live with less maximum volume, you could add a 470k resistor in series with the top end of each section which would leave the circuit untouched as far as the amplifier is concerned.


So far as upsetting the amplifier with a single pot mod is concerned, the area in question is outside any feedback loops and as such as long as there's a dc path to ground for the grid you can't do anything upsetting. It's also outside the tone control circuit so it won't have any effect on the function of that either. It will have some effect on the overall frequency response compared with the original circuit at low volume settings as already mentioned.

stumted2 7th Sep 2019 9:56 am

Re: 1 Meg ganged log pot
 
Hi Herald 1360,

Many, many thanks for your fantastic help, its very kind of you to take the time to help a lesser confused mortal like me.

this player has had a high output cartridge fitted at some time in the past (Presume it should have a medium output cartridge fitted) so is quite loud, but on the other hand the single pot seems much more straightforward.

Decisions, decisions, my kingdom for a decision. I will go now and lie down in a dark room to ponder.

Many, many thanks for all your very much appreciated kind help and words.

All my very best and kindest regards,
Ted. (The old ponderer)

stumted2 8th Sep 2019 11:45 am

Re: 1 Meg ganged log pot
 
Does any kind member have any idea where I may purchase a pot shaft coupler/extender?

The shaft on my replacement shaft is too short.

Cheers,
Ted.


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