Classic or Skyliner? Rebuilding a VHT D-50

[talbany]

The 716's are Polypropylene..Ian and just to elaborate on the grit comment?
So if I were to describe them in "Cork sniffer" terms vs a PS it would be a Brighter cap ..So IMO it's not really grittier it's that you notice the grit more because why? It's brighter ..So Dumble used them in his more aggressive amps like Bluesmaster because he wants to hear that grit..Basically the same effect with metal film resistors,which are also brighter (vs Carbon film and especially a C.C.)
So in the case of the VHT you have both so the amp will be overall brighter and therefore more aggressive (Grittier)..Over time those 716's will smooth out (Darken some).
Those 716 (steel leads)are also great to use in some spots if want to brighten the mids up either in the OD (183) or if you want to brighten up the mids on a high plate clean, you simply sub out the PS mid cap for a 715 or 716 will give you a nice chime in the upper midrange frequencies (500/1K)

BTW.Dumble used them in the Tweedle dee Charlie posted because he wanted a more "Rock" type sound out of his Les Paul. So you simply load it with the grit caps. This is a good example of the Genius that is H.A.D to pick the right parts for what the player (or he)was after and not just stick any ole thing in there that worked

If you want to brighten the treble use a Silver mica..If you want to brighten the mids use Polyprop..Cooking with caps
Tony

[ijedouglas]

Thanks Tony. Great explanation on the 716s. I've tried the 715 mid cap in my 102 and really liked it but ended up with an El Menco for that position. I think if Tony D wants to tame the amp, I would probably change out those 716s to take off some of the edge.

[talbany]

Thanks Tony. Great explanation on the 716s. I've tried the 715 mid cap in my 102 and really liked it but ended up with an El Menco for that position. I think if Tony D wants to tame the amp, I would probably change out those 716s to take off some of the edge.

Oh totally agree!! I would have already yanked em.
In order of brightness in the Sprague line you have from bright to dark are
1. 716 (Steel leads)
2. 715's (copper leads)
3. PS polyester
4. 220P Difilms.
The 220P's and the EL Menco very similar texture (depending on age)
I encourage everyone to experiment around with different caps in various spots as this is a great way to fine tweak each section of the amp for better balance!
I find the Higher 1200V 715/16's ala (183) will give you a slightly tighter low end vs the 600V ones

BTW..Normally low plate amps are plenty bright and don't really require one I've found? but I have to have polyprop (or something bright) as a mid cap in all my high plates

Tony

[dorrisant]

So the Polester/Polyprpylene combo yields slightly reduced highs and the perception of smoother OD...? Making sure. These?

Orange Drop Type PS.pdf

I will drag my feet until I have solidified the BOM. Let me know if you see anything that looks like it should be upgraded. The 20M on the relay board will get changed out too... already have that one on the list.

I must give a big Thank You to everyone who is following. Your knowledge and direction is double-effective making two people at the same time. I appreciate all of it. No criticism will be rebuked!

Seriously though, thanks guys.

[ijedouglas]

Hi Tony,

Correct on the ODs for the OD . Make sure you get the 600V 6PS version.

Upgrades all depends on how much you want to spend and how close you want to get

I would change the 500pf V2b snubber cap on the 220K from mica to ceramic. I know some folks like it but I tried it and didn't like it. Maybe something to try. The 68K V2A grid was a 2 watt piher. You may want to try that (or a CF) instead of the MF.

Are you trying to approximate a 183?

[talbany]

So the Polester/Polypropylene combo yields slightly reduced highs and the perception of smoother OD...? Making sure. These?

The easiest way to think about it would be the same as using say a Silver mica vs a Ceramic treble cap
the Silver micas are brighter than the ceramics so your sound is going to be more sterile some call it harsh or buzzy because your hearing that grit in the "Treble" frequencies..This is why a lot of players don't care for them (in the stack) especially in an amp with overdrive..
Basically it's the same concept when using a Polyester vs Polyprop coupling cap except in that application your hearing mostly brighter (upper) mid frequencies (not treble freq)..This is why I call a polypropylene cap the silver mica of mid caps..The more polypropylene caps you use in an amp the brighter the mids the less scooped and the more obvious the grit becomes..In the last post I listed brighter to darkest..Generally the best way to approach it is do the entire amp in OD 6PS caps.. If then after you have played it a while and want to brighten up (or add in some grit) in a section of the amp sprinkle in a 715/716 in whatever area of the amp sounds best like the mid cap or in the OD side (like HAD did in 183) If you want to darken/scoop that circuit then use a 220P Difilm! or an old El Menco

Also don't forget to orient the caps correctly to help keep the signal as clean/pure as possible

Hope this helps

Tony

[dorrisant]

Quick question...

What are the composition and wattage of the following:

All in the PI

820R
24k (would 22k work here? I have read that the brand\composition may be more important than the exact value.)
390R

CC good enough for the 68k OD entrance?

Also, what about the 4k7 NFB?

I think I have some Dralorics and Roedersteins, but will have to round out what I don't have with a few MFs and CFs from CED. I will be ordering a few 6PSs (.1u, .047u (LNFB), .02u and .005u). I will order some more ceramic caps too, just to round out my stash.

20210827_220858.jpg

Any concerns about the 4u7s?

I don't know what to get for the NTEs (.1u and .002u). Anything at CED good enough?

So many questions!!!

[ijedouglas]

Quick question...

What are the composition and wattage of the following:

All in the PI

820R
24k (would 22k work here? I have read that the brand\composition may be more important than the exact value.)
390R

CC good enough for the 68k OD entrance?

Also, what about the 4k7 NFB?

I think I have some Dralorics and Roedersteins, but will have to round out what I don't have with MFs and CFs from CED. I will be ordering a few 6PSs (.1u, .047u (LNFB), .02u and .005u). I will order some more ceramic caps too, just to round out my stash.

20210827_220858.jpg

Any concerns about the 4u7s?

I don't know what to get for the NTEs (.1u and .002u). Anything at CED good enough?

So many questions!!!

1/2 watt CF in the PI

PI plates and grids are NTE MF

V2a grid 68K 2 watt piher

NFB 1 watt NTE metal oxide

The ROE gold caps are what I currently have in my 183 and they sound great

[dorrisant]

Thanks again, Ian. You have been so helpful.

I tried looking for the 2w 68k Phier. The only one I can find quickly will not ship here to the states, I guess. Maybe I can find a lower wattage.

https://www.ebay.com/itm/68K-Ohms-2W-Pi ... 635-2958-0

Wait, maybe this one:

https://www.ebay.com/itm/Vintage-piher- ... 638-7840-0

Would anyone care to help? I'll pay the shipping. If not, I'll find the best thing I can.

What caps can I use for those NTEs? Metalized film?

[ijedouglas]

Thanks again, Ian. You have been so helpful.

I tried looking for the 2w 68k Phier. The only one I can find quickly will not ship here to the states, I guess. Maybe I can find a lower wattage.

https://www.ebay.com/itm/68K-Ohms-2W-Pi ... 635-2958-0

Wait, maybe this one:

https://www.ebay.com/itm/Vintage-piher- ... 638-7840-0

Would anyone care to help? I'll pay the shipping. If not, I'll find the best thing I can.

What caps can I use for those NTEs? Metalized film?

Hi Tony,

I was wrong on the piher 2W. I just checked my amp and stash and it looks like it's a 1 watt resistor. 2 sellers on eBay (Italy/Spain)

[dorrisant]

Thanks Ian. I think the layout from the files shows a large resistor there but doesn't specify it as a 2w. I don't really know where the idea of 2w came from. 1w would be quieter there relative to 1/2w. I wonder if this was done to cut down on shot noise in this most sensitive area.

[ijedouglas]

Thanks Ian. I think the layout from the files shows a large resostor there but doesn't specify it as a 2w. I don't really know where the idea of 2w came from. 1w would be queiter there relative to 1/2w. I wonder if this was done to cut down on shot noise in this most sensitive area.

It may very well be but I think he used it because he liked the way it sounded. I think he would have used 1 or 2 watt throughout the amp if noise was an issue

[talbany]

Thanks Ian. I think the layout from the files shows a large resistor there but doesn't specify it as a 2w. I don't really know where the idea of 2w came from. 1w would be quieter there relative to 1/2w. I wonder if this was done to cut down on shot noise in this most sensitive area.

Shot noise is dependent upon current, so the more average DC current through a resistor, the more noise you get, so we know there is quite a bit of current coming from the Opt-Sec to drive the voice coils..Dumble was particularly fond of 1 watt Phiers in that spot in quite a few of the early Grail ODS amps..I agree with Ian in that he chose that resistor for it's sonic qualities..The later amps he then switched over to 1W metal oxides NTE (183) and in the HRM's


Tony

[dorrisant]

Yes, I have to remember, sound (tone) first!

[M Fowler]

Tony,

I answered your message sent to me.

Mark