DHT OTL Linestage - Tram 2 - Page 21 - diyAudio
Go Back   Home > Forums > Commercial Sector > Vendor Forums > DIY HiFi Supply

DIY HiFi Supply Parts and Kits from Diy HiFi Supply

Reply
 
Thread Tools Search this Thread
Old 5th July 2011, 10:28 AM   #201
jacklee is offline jacklee  Hong Kong
diyAudio Member
 
Join Date: Oct 2009
Quote:
Originally Posted by ThorstenL View Post
Hi,



Try gently "pinging" the tube with a biro or the like.

See if this creates the same noise.

Ciao T
I just tried pinging the tube. It does not creates the same noise. The tube is not very microphonic and I already used Herbie tube damper on it.

The audible noise is closer to a sine wave type, very high in pitch - probably over 10KHz.

Thanks.

Jack
  Reply With Quote
Old 5th July 2011, 03:39 PM   #202
jacklee is offline jacklee  Hong Kong
diyAudio Member
 
Join Date: Oct 2009
An update: I tried disconnecting the subwoofer connections again and this time it seems to eliminate the noise. The sub was connected via Jensen's isolation transformer (to prevent hum) and perhaps the extra inductance interacted with the preamp.

I now bypassed the isolation transformer and it seems to remain stable, and no hum too. I'll report back if this does not eliminate the noise.

Thanks.
Jack
  Reply With Quote
Old 7th July 2011, 01:10 PM   #203
reggie is offline reggie  Australia
diyAudio Member
 
Join Date: Feb 2010
Location: melbourne australia
Hello from Melbourne, Australia. I wonder if anyone can help me/advise me on a problem I am experiencing with my recently purchased TRAM MK11 (bought as a complete unit). I've read the previous posts but none exactly match my particular situation. The day I got my TRAM it played for about 10 minutes before one channel went out. So, I returned it to DIY Hifi in Hong Kong for repairs. When I got it back it again played for about 10 minutes before I heard a throbbing sound from one of the speakers. I got up to have a look and I noticed that the left hand 2A3 tube on the TRAM (the same channel as before) was waxing and waning and the relevant monoblock valve amp was oscillating. So I turned it off. After 1/2 an hour or so I turned it back on and after 10 minutes it started doing it again. As I had just purchased some inexpensive Shuguang tubes I replaced the Full Music 2A3's and....the Tram has worked faultlessly now for several weeks. At the suggestion of Simon from DIYHifi I had both sets of 2a3 tubes tested. The results were that the Shuguang's were pulling 48 milliamps and the Full Music 72 milliamps. So, what do I have to do to (a) get the very expensive Full Music tubes to work in the Tram and (b) ensure that any future tubes I purchase buy will also work? As to the TRAM I think I like it. I was previously using a Bent Audio TAP-X but I think the TRAM gives me the same clarity but a more emotional response. It's a very intangible thing. I don't have any trouble with hum even using unshielded Mapleshade copper interconnects. But I do use the -12db output which gives me the required volume at around the 3.00 o'clock mark.
Anyway, I hope someone can help me. PS I'm not technically minded.
  Reply With Quote
Old 8th July 2011, 12:27 PM   #204
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by reggie View Post
The results were that the Shuguang's were pulling 48 milliamps and the Full Music 72 milliamps. So, what do I have to do to (a) get the very expensive Full Music tubes to work in the Tram and (b) ensure that any future tubes I purchase buy will also work?
Unfortunatly different batches of TJ/Full Music Tubes seem to vary a lot.

I suspect the Full Music Tubes you have are not really matching real 2A3's to well electrically. I suspect their heater current exceeds 2.5A by quite a lot, which would explain the extra anode current.

I do not think these tubes will ever be usable in the Tram II.

If you purchased them from diyhifisupply together with your tram please negotiate with Simon to return them, ask Simon to talk to me if he has any issues.

For future purchases, I guess either buy real 45 or 2A3 (NOS) or make sure the seller tests both heater and anode current.

Ciao T
  Reply With Quote
Old 9th July 2011, 04:49 PM   #205
dth31 is offline dth31  United States
diyAudio Member
 
Join Date: Dec 2007
There has been a similar thread on the Bottlehead forum about challenges of using TJ2A3's in the Paramount amps. If I were a designer/manufacturer of amps, that sort of thing would drive me crazy. One would think that tube manufacturers would control such vital operating parameters closely, but then that would obviously be a wrong assumption.

Thank goodness honest manufacturers and designers like Brian, Thorsten and Doc let their customers know about the challenges and help them work thru them rather than ignore them! It's one reason I've bought 3 amps and 1 preamp from Brian--great customer service, great value, always honest, and fantastic support from Thorsten.

Thanks Thorsten!
  Reply With Quote
Old 12th July 2011, 07:08 AM   #206
reggie is offline reggie  Australia
diyAudio Member
 
Join Date: Feb 2010
Location: melbourne australia
Thank you Thorston for your quick response. Unfortunately, I did not purchase the Full Music tubes from DIYHiFi so I will have to wear the cost until I can sell them. I'm presuming they are good tubes even if I cannot utilise them in the TRAM. Thorston, I wonder if you would assist me further with three questions regarding the TRAM. 1. In future, when buying a replacement set of tubes for the TRAM what details should I be asking the seller? The reason I ask this is because there is a Tube Shop that advertises on Ebay that has new EHx 2A3 tubes for about $US100 where the buyer can request tubes to a specific Transconductance (GM) and Current Draw (lp)(obviously only if they have them to those values). 2. I see that in your reply to my initial query you suggest I should be using NOS 45 or 2A3 tubes in the TRAM. Is there a reason for using NOS and are 45 tubes a "better" tube for the TRAM or are they just "different" to the 2A3's? And lastly, on my push pull mono block valve amps (utilising 2 x 6550 and 2 x AT7 tubes each) I have the facility to switch between Triode and Ultralinear. When I received my TRAM back from Simon and got things working with the Shuguang 2A3 tubes the mono-blocks were set to Triode. Yesterday I thought I would listen in Ultralinear. Within 3 minutes (warm up time) I had a thump thump through one speaker and the tubes in the relevant mono block were oscillating and flashing purple. Am I cursed or is there a (simple) explanation?
Regards
Reggie
  Reply With Quote
Old 13th July 2011, 05:49 AM   #207
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by reggie View Post
Thank you Thorston for your quick response. Unfortunately, I did not purchase the Full Music tubes from DIYHiFi so I will have to wear the cost until I can sell them. I'm presuming they are good tubes even if I cannot utilise them in the TRAM.
Yes, they will work, however for preamp application there is less tolerance that can be allowed.

Quote:
Originally Posted by reggie View Post
In future, when buying a replacement set of tubes for the TRAM what details should I be asking the seller?
For 2A3's of current production I would ask for confirmation of heater current being normal. Several manufacturers ones may have significantly higher heater currents.

Quote:
Originally Posted by reggie View Post
The reason I ask this is because there is a Tube Shop that advertises on Ebay that has new EHx 2A3 tubes for about $US100 where the buyer can request tubes to a specific Transconductance (GM) and Current Draw (lp)(obviously only if they have them to those values).
The Tram II can tolerate quite a range of variations in these parameters. Heater current is a different issue.

Quote:
Originally Posted by reggie View Post
I see that in your reply to my initial query you suggest I should be using NOS 45 or 2A3 tubes in the TRAM. Is there a reason for using NOS and are 45 tubes a "better" tube for the TRAM or are they just "different" to the 2A3's?
Personally I like 45's better, we would still recommend the TJ/Full Music 45 for the Tram, if the new batches had not turned out to be so good at picking up the slightest noise. The best in the Tram II IMNSHO are NOS 45's.

Quote:
Originally Posted by reggie View Post
And lastly, on my push pull mono block valve amps (utilising 2 x 6550 and 2 x AT7 tubes each) I have the facility to switch between Triode and Ultralinear.

....

Yesterday I thought I would listen in Ultralinear. Within 3 minutes (warm up time) I had a thump thump through one speaker and the tubes in the relevant mono block were oscillating and flashing purple. Am I cursed or is there a (simple) explanation?
I do not know anything about your Amplifiers, but tubes with flash-overs suggests an electrical fault or that the tubes ratings where exceeded. Do you have very high local mains voltage?

It would also explain the problems with the Full Music Tubes if higher then spec. mains voltages and higher than spec heater current combine...

Ciao T
  Reply With Quote
Old 21st July 2011, 11:57 AM   #208
diyAudio Member
 
Join Date: Jul 2011
Location: Amsterdam
Hi everyone, I too was affected by the Tram mkII virus and ordered a complete assembled Tram last month. I received the pre-amp 24th june and from that day I am having problems with it. First I heard a hum at the 6db output connection and after this the left channel starting to go silent. Several emails were sent to Simon and the technical support desk. I was told to bias the dht tubes. As I am not a too technical guy I ask Simon to give me a full disciption of the procedure. Simon told me to make me a video instruction guide but up till now I haven't receive any. I have read/spelled the bias procedure in the manual and tried to bias the dht tubes with a Fluke 177 meter and set the parameter about 120v. The left channel showed more than 135v and was going up. After this I inserted the Tram into my gear and at first both channel was playing and after a few minutes the left channel went silent. The next day I biased the DHT tubes again. The multimeter was showing about 126v for left and 125v for right. I set both channels at 120v and inserted the Tram in the hifi chain. Again both channels were playing for a few minutes and the left channel went silent. I sent this data to Simon and I'm hoping he will make the video instruction soon that will shed some light on something I might be overlooking. At this moment my interest in the Tram is very low because of the remaining problem. If someone has an idea how to deal with this problem you are most welcome to contribute for which I thank you very much.

Eugene
  Reply With Quote
Old 22nd July 2011, 04:03 AM   #209
rnxrx is offline rnxrx  United States
diyAudio Member
 
Join Date: Jul 2011
Location: Arlington, VA
Default Alternate tubes?

Hi-
With adapters (UX4 -> UY5) it's possible to substitute 46, 47 and even 71A tubes for the 45/2A3 - at least for output tubes in certain amplifiers. Would any of these tubes be drop-in substitutes in the TRAM2 and, if not, what level of modification would be required to make them work?

Thanks!
  Reply With Quote
Old 22nd July 2011, 08:55 AM   #210
diyAudio Member
 
Join Date: May 2003
Location: UK
Quote:
Originally Posted by eabeemer View Post
Hi everyone, I too was affected by the Tram mkII virus and ordered a complete assembled Tram last month. I received the pre-amp 24th june and from that day I am having problems with it. First I heard a hum at the 6db output connection and after this the left channel starting to go silent. Several emails were sent to Simon and the technical support desk. I was told to bias the dht tubes. As I am not a too technical guy I ask Simon to give me a full disciption of the procedure. Simon told me to make me a video instruction guide but up till now I haven't receive any. I have read/spelled the bias procedure in the manual and tried to bias the dht tubes with a Fluke 177 meter and set the parameter about 120v. The left channel showed more than 135v and was going up. After this I inserted the Tram into my gear and at first both channel was playing and after a few minutes the left channel went silent. The next day I biased the DHT tubes again. The multimeter was showing about 126v for left and 125v for right. I set both channels at 120v and inserted the Tram in the hifi chain. Again both channels were playing for a few minutes and the left channel went silent. I sent this data to Simon and I'm hoping he will make the video instruction soon that will shed some light on something I might be overlooking. At this moment my interest in the Tram is very low because of the remaining problem. If someone has an idea how to deal with this problem you are most welcome to contribute for which I thank you very much.

Eugene
Eugene, how long after seeing the bias at 120V (or close) are you turning off the Tram? I find 5 mins sometimes isn't enough. You may need 15 mins. You need to wait until the voltage stops going up (or down, whichever it is) and instead starts to react to the normal fluctuations on your mains.

Re the hum, do you need to use the +6db connection for your amp/speakers? If you use too high an output you will hear hum.
  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
C3M linestage costa23 Tubes / Valves 15 23rd August 2009 09:53 AM
C3m linestage bequerel Tubes / Valves 32 14th April 2009 07:03 AM
48V B+ linestage hirafu_boarder Tubes / Valves 24 11th May 2008 06:57 PM
Another linestage...... kianbach Tubes / Valves 11 28th June 2005 06:34 PM
:: linestage [Bryston B60] :: dhengkoel Solid State 6 26th September 2002 04:32 PM


New To Site? Need Help?

All times are GMT. The time now is 03:23 AM.


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