The all DHT SET Headphone Amp - Page 36 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 9th February 2013, 07:06 PM   #351
diyAudio Member
 
Join Date: Oct 2010
Location: se england
With the greatest respect I'm not sure i agree with all your maths re operating point. I don't think we should worrie too much about straying into A2 if we're willing to accept some sort of ss mu output, be it dc gyrator or something along the Rod Coleman idea. If 2.5W A2 is doable (real world tested) into 8r i struggle to believe we're limited to 0.2W into 38r.
I'm no expert, so I'm happy to be told i'm wrong. Will have a closer look at the curves.

enzo
  Reply With Quote
Old 9th February 2013, 07:13 PM   #352
iko is offline iko  Canada
diyAudio Moderator
 
iko's Avatar
 
Join Date: May 2008
Location: Toronto
Quote:
Originally Posted by regal View Post
If anything I think this thread has shown that it is tougher to build a headphone SET and really tough to beat the shunt reg spud amps a few of us have been building.
I think the real lesson is that it's tough to please everybody with one single amp; a crazy undertaking IMHO. There were enough suggestions that would cover almost every request.
  Reply With Quote
Old 9th February 2013, 07:20 PM   #353
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
According to my calculations and experiments, you can get up to 1.8W of clean power in A1, or 2.5W in A2. from a single 4P1L.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 9th February 2013, 07:32 PM   #354
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
Quote:
Originally Posted by Wavebourn View Post
According to my calculations and experiments, you can get up to 1.8W of clean power in A1, or 2.5W in A2. from a single 4P1L.
Interesting, could you post the schematic.
  Reply With Quote
Old 9th February 2013, 07:37 PM   #355
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by merlin el mago View Post
Interesting, could you post the schematic.
You can find it somewhere on one of previous pages, with the link to my original thread about "One more 4P1L SE"
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 9th February 2013, 07:37 PM   #356
diyAudio Member
 
Join Date: Oct 2010
Location: se england
I use sennheiser hd580 precisions thru an OE-MU 0204, its rated at 16mw, I think it puts out 5.6v peak ~22ohm Zout and that pretty much does me. the advantage of ~300ohm cans!
Enzo
  Reply With Quote
Old 9th February 2013, 08:44 PM   #357
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
This afternoon I drove the 4P1L output directly with a 1:5 step up transformer. It was enough for my SD580 cans on a 25:1 output. It seems to me that a 5:1 OPT (5K:200R) would give plenty of voltage for headphones in the 300 ohm range.

The trouble with input step-up transfo was that bass distortion was awful. Not really usable below 200Hz. Still, with a 5:1 OPT you could use a less aggressive, and maybe better sounding, input transformer to drive the 4P1L grid. 1:2 should it.

Horses for courses, I say. Trying to build a DHT headphone amp that can drive any and all headphones makes about as much sense as a DHT amp that can drive any and all speakers. You could do it, but why?
__________________
Take the Speaker Voltage Test!
  Reply With Quote
Old 10th February 2013, 01:01 AM   #358
regal is offline regal  United States
diyAudio Member
 
Join Date: Jan 2004
Location: MD
Part of this thread's purpose was to show how difficult it is to design an all purpose headphone amp. To show the pitfalls that are unique to headphones, its not as easy as building a pre-amp or even an SET for full range drivers.

This transformer Sowter Type 8650 Headphone Output transformer parafeed with a single 6C45p will power any non-ortho dynamic headphone except the AKG K1K's. Thats a lot of headphone selection. Whether you use a 6c4p,cg3m, one of the many high gm triode strapped pentodes doesn't matter they all have more linearity than a 2 stage DHT amplifier. They are all based on aWE437 spud schematic posted Lyn Olsen's website over 10 years ago, its the benchmark for the headphone SET amplifier

The Frank Cooter schematic I posted on the first page is sort of the DHT alternative, same power, same selection of headphones with the right transformer, a bit less linearity. We could build a variation of his design with the 4P1l and get a little more power but not much. Its an excellent alternative if you want DHT sound but don't care about modern headphone.

The new ortho headphones and the old K1K are the real reason to consider building a DHT output SET amp asa 2A3/300B/PX4 with a scaled up version of the Sowter 8665 would power any headphone driven by a 6n1p ccda. I was hoping to find an all DHT alternative (I don't really like 6Dj8's) and Rod came up with a really unique way to drive a 2A3, I think if it was parafeed (so one wouldn't have so much secondary loss) then it would power any headphone.
Wavebourne also posted a great schematic for A2 driven 4P1l that would handle the new orthos.

Headphones are different than speakers in that its hard to live with just one pair,its easy to end up with too many. The last thing you want is to hear a new headphone design only to find that your "masterpiece" SET won't work with them.

Last edited by regal; 10th February 2013 at 01:06 AM.
  Reply With Quote
Old 10th February 2013, 01:21 AM   #359
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Sure, I think you've made your point - no argument from me. There is probably more variation in headphones than in speakers. But I would not be surprised or disappointed if the lovely DHT SET amp I had built for my horn loaded system did a poor job of driving the new Magnepans I just bought. Why should headphones be different?

I think that a single stage 4P1L with the right transformers could do a fine job of driving a lot of headphones.
__________________
Take the Speaker Voltage Test!
  Reply With Quote
Old 10th February 2013, 02:02 AM   #360
regal is offline regal  United States
diyAudio Member
 
Join Date: Jan 2004
Location: MD
When the SSHV came out, many of us built variations on the Gary Dahl spud headphone amp but there was really no thread of discussion.

For a spud 4P1l, just build a separate case for the power transformers/rectifier/prefiltering, a pair of SSHV2's, coleman filament bias and a Sowter 9650, Peerless TL404, or slagle autoformer parafed output. Not much to discuss but certainly a worthwhile build for very efficient headphones. I did did something similiar with the 71A but didn't find less distortion than a WE417A, just not enough gain for some headphones.

Its the new orthos that make things tough yet interesting.

headphone SET's can be broken down to three types and their pioneer:

1. high gm spud (Gary Dahl's Espressivo)
2. two stage dc coupled 71A/45/4P1L all DHT type (Frank Cooter)
3. The two stage IDHT to 2A3/300B/PX4/EL34 (Eddie Current/Moth)
4 the 633c/6as7 (Eddie Current)

With Rod's work #2 & #3 are well within reach for the DiYer and we couldn't say that a few years ago, and his shunt cascode brings #2 closer to #3.

Last edited by regal; 10th February 2013 at 02:07 AM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
High end Ortho Amp on a basic Russian Tube DHT SET DIY design regal Headphone Systems 2 7th December 2012 11:46 AM
300b all-DHT SET andyjevans Tubes / Valves 16 24th August 2012 08:06 PM
Help on designing full DHT SET power amplifier milen007 Tubes / Valves 56 11th August 2011 09:38 PM
Class A, DHT driven, headphone amp iko Headphone Systems 100 26th March 2011 02:54 PM


New To Site? Need Help?

All times are GMT. The time now is 01:21 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2