Use the chassis for a Pass Diy preamp. It would cost more to update the Pat 4 and it still wouldn't compare with any decent current DIY design. The Pat 4 topology is too dated to be worth the effort to replace the caps and resistors with new ones.
Von Alstine Mods
Here's a link to an article with PAT-4 mods suggested by Von Alstine. The PAT-4 mods begin on page 29:
http://avahifi.com/images/avahifi/root/audio_basics/ab_pdf/ab1986.pdf
This link was suggested to me by one of my customers who purchased my Stereo 120 upgrade kit
Update My Dynaco
Here's a link to an article with PAT-4 mods suggested by Von Alstine. The PAT-4 mods begin on page 29:
http://avahifi.com/images/avahifi/root/audio_basics/ab_pdf/ab1986.pdf
This link was suggested to me by one of my customers who purchased my Stereo 120 upgrade kit
Update My Dynaco
I am working on a PAT-4 rebuild using an ESP P88, with new power supply, switches, controls, and connectors. I do not require a phono preamp so that piece is omitted. The chassis is somewhat small but I can fit the new parts and have some room left over for future additions or changes. If you need any original electronic PAT-4 parts, let me know. I am only using the chassis and a few mechanical parts from the original preamp.
DJoffe's (UpdatemyDynaco)Tiny ~$10 mods are in my experiences THE best upgrade I've run accross for My pat4.
And I've looked at pretty well ALL of them.. since '72
Having done these tiny/simple upgrades the thing now works Very Well indeed.. Dead silent! Even the Tone controls actually work, when turned on.
Seriously impressive. Although In fairness, in the past I did a bespoke Sonic Frontiers (when they were still new 🙂 parts replacement upgrade,(their Business shtick was Premium parts = Premium sounds. Ultimately proven as woefully inaccurate.. but that's history) which was in essence an across the board Resistor ( Holcos) )replacement as well as an electrolytic replacement ( Solens ).
In truth the SF upgrade did help.. some. Pat4 became a bit clearer/sparklier.
But not until Daniel's wee /inexpensive intervention parts/kit did the PAT4 Come Alive.
Genuinely Recomended.. Go ahead, risk! the ~$10. Be a Fool not to IMO.
The thing is now 'at least' equal to current equipment, seriously.
Van Alstine? I wouldn't let them near your Dynas, let alone mine.
PS: Daniel... Phono section upgrades ?? Yess I'm wanting to use the thing on my Vinyl.
NO.. no affiliation Nor Shilling involved 🙄
Simply that there is Sooo much smoke and mirrors in Audioland that anything that actually does what it says it will.. is outstanding.
And I've looked at pretty well ALL of them.. since '72
Having done these tiny/simple upgrades the thing now works Very Well indeed.. Dead silent! Even the Tone controls actually work, when turned on.
Seriously impressive. Although In fairness, in the past I did a bespoke Sonic Frontiers (when they were still new 🙂 parts replacement upgrade,(their Business shtick was Premium parts = Premium sounds. Ultimately proven as woefully inaccurate.. but that's history) which was in essence an across the board Resistor ( Holcos) )replacement as well as an electrolytic replacement ( Solens ).
In truth the SF upgrade did help.. some. Pat4 became a bit clearer/sparklier.
But not until Daniel's wee /inexpensive intervention parts/kit did the PAT4 Come Alive.
Genuinely Recomended.. Go ahead, risk! the ~$10. Be a Fool not to IMO.
The thing is now 'at least' equal to current equipment, seriously.
Van Alstine? I wouldn't let them near your Dynas, let alone mine.
PS: Daniel... Phono section upgrades ?? Yess I'm wanting to use the thing on my Vinyl.
NO.. no affiliation Nor Shilling involved 🙄
Simply that there is Sooo much smoke and mirrors in Audioland that anything that actually does what it says it will.. is outstanding.
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Bare...
I'm actually hard at work on some simple phono mods that should do some nice things. I'm a bit conflicted now, as there are a couple of levels of things that can be done, and I'm trying to figure out what combination(s) make the best sense.
Dan
I'm actually hard at work on some simple phono mods that should do some nice things. I'm a bit conflicted now, as there are a couple of levels of things that can be done, and I'm trying to figure out what combination(s) make the best sense.
Dan
Hi Dan,
I just picked up a PAT-4 from eBay and would like to upgrade it using your mods and Van Alstine's and would sincerely appreciate your feedback and help. Here is what I have in mind:
AVA mods:
- Cancel Bass & Treble control out of the circuit
- Upgrade and replace caps, as per Audio Basics Newsletter
updatemydynaco.com:
- Power Supply upgrade
- Distortion Reducer upgrade
- Adding more high level inputs
Additionally, I would like to do the following:
- Cancel Balance Control. Would appreciate some instructions on that!
- Cancel Loudness Switch. Would appreciate some instructions on that as well!
- Upgrade the power switch to a Blue one as in your mod, but I would like to use a push button instead of the rocker switch. Is this possible, and if so what switch can be used as a direct drop-in?
- Upgrade the phono section as in your post above. Is this ready?
Any and all help, criticism, etc. is appreciated.
Thank you.
As an alternative to removing bass and treble permanently, you could install the Tone Control Switch:
Update My Dynaco Store
Upgrading electrolytic coupling caps can help the sound.
The updatemydynaco power supply upgrade is definitely the way to go...
The DRD4 drops the high level stage distortion by a factor of 10.
You can wire around the balance control...if you're really interested, drop me a PM and I can send directions.
If you leave the loudness switch off, there is no effect on the sound, so I wouldn't do anything to fool with it.
There may be a drop-in pushbutton, but I haven't found it.
Getting more high level sources is a bit at odds with the phono section improvement.
Phono section improvement...I can send you some notes on that after you get thru the rest...I never quite distilled it to a product as I'm working on a new preamp design, and that's kept me pretty busy.
All the stuff you're doing should be both fun and rewarding, as well as educational...
best of luck...
Dan
Update My Dynaco Store
Upgrading electrolytic coupling caps can help the sound.
The updatemydynaco power supply upgrade is definitely the way to go...
The DRD4 drops the high level stage distortion by a factor of 10.
You can wire around the balance control...if you're really interested, drop me a PM and I can send directions.
If you leave the loudness switch off, there is no effect on the sound, so I wouldn't do anything to fool with it.
There may be a drop-in pushbutton, but I haven't found it.
Getting more high level sources is a bit at odds with the phono section improvement.
Phono section improvement...I can send you some notes on that after you get thru the rest...I never quite distilled it to a product as I'm working on a new preamp design, and that's kept me pretty busy.
All the stuff you're doing should be both fun and rewarding, as well as educational...
best of luck...
Dan
My brother has a pat4 that Van Alstine gutted and re-stuffed with his boards. 22 years later one channel was quietter than the other...so he had them service it. Still sounds good to me when I listen at his house. But the Van Alstine "update" is now a 27 year old design. And to tell the truth, IMHO it isn't that great a chassis...mediocre switches etc.
Another PAT4 Improvement
I'm getting a custom toroidal transformer made for PAT4 Preamps. It drops the hum a bunch...more details here:
PAT-4 Replacement Transformer
I'm getting a custom toroidal transformer made for PAT4 Preamps. It drops the hum a bunch...more details here:
PAT-4 Replacement Transformer
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