DHT OTL Linestage - Tram 2

[jacklee]

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

 

[jacklee]

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

 

[reggie]

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.

 

[ThorstenL]

Hi,

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

 

[dth31]

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!

 

[reggie]

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

 

[ThorstenL]

Hi,

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.

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.

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.

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.

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

 

[eabeemer]

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

 

[rnxrx]

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!

 

[clivetjm]

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.

 

[eabeemer]

Hi Clivetjm, thanks for your reaction. First time I was about 30 minutes busy setting the bias. Next tme I was about 2 hours busy setting the 120v because I wanted to make sure that it wouldn't drift either way. I have shut down and separated the amp now for several days and today I will look again at the bias. I don't need the 6v output but wanted check out if all the outputs were working properly.

Eugene

 

[eabeemer]

Today I did the bias procedure and noticed that the left channel showed 121v and the right channel 105v. I set both channels about 120v, this procedure took me about
a little hour. I then inserted the pre-amp into my hifi chain. For about
an hour it played through both channels before the left channel start
playing on and off. I took the amp apart and did the bias procedure again.
The left channel showed 123v and the left channel 119v. I set both
channels about 120v and inserted the amp into my hifi chain. Only the
right channel was working. What I noticed is the longer the pre-amp is
playing the more only one channel (right) is working. The left channel
remains silent. I have sent Simon an email about this.
If someone here have a clou for this problem, please let me know, for which I thank you in advance.
Eugene

 

[reggie]

Hi again from Melbourne, Australia. Picture this: cold winters day, open fire burning in the grate, me lounging about listening to Madeleine Peyroux's "Dance Me to the End of Love" (from her very well mastered album Careless Love - Rounder Records) on my valve gear. "How good's this" I say to myself about 10 seconds before I lose sound from the right channel and I see the equivalent 2A3 tube in the TRAM has gone out. "For goodness sake!!!!", I say to myself. I'll turn it off, wait a bit for it to cool down and then swap tubes. But, no. I'm out of luck. It's not the tube it's the channel. So, after 3 weeks of bliss, it's let me down again. First the left channel goes within 10 minutes of buying the damn thing - necessitating me sending the entire TRAM back to Hong Kong ($180). Then I have to purchase new Shuguang 2A3 tubes because the expensive Full Music tubes don't suit the TRAM. And now, no right channel. You know I think I'm starting to see a pattern here. Eugene, I don't have a cure for your problem but it is obviously the same problem I and a few others are having. Thorston, Simon, Brian Cherry, tell us what we are supposed to do now?

Reggie

 

[ThorstenL]

Hi Reggie,

I see the equivalent 2A3 tube in the TRAM has gone out.

Gone out you mean "heater is not lit up" right?

This would suggest the heater supply is out.

Thorston, Simon, Brian Cherry, tell us what we are supposed to do now?

Could you measure the mains voltage at the wall?

Ciao T

 

[reggie]

Hi Thorsten. Sorry if I sounded peeved in my last post. Anyway, yes the heater supply on the (right channel) 2A3 tube is out. Having taken my life in my hands I measured the voltage from the wall socket (with my little digitech multimeter). I kept the probes in for about 30 seconds. The voltage varied between 253 and 257. It's now 6.15pm on a Sunday evening so whether that has an effect I'm not sure. I hope the TRAM factory used the appropriate 240 volt thingies instead of Hong Kong thingies (110 volts???). Where to now??

Regards

Reggie

 

[ThorstenL]

Hi Reggie,

I kept the probes in for about 30 seconds. The voltage varied between 253 and 257. It's now 6.15pm on a Sunday evening so whether that has an effect I'm not sure.

First, this being sunday eve may contribute, but whatever it is it is very high. You may wish to take a few more measurements.

According to EN 50160:2007 the "Harmonised supply voltage" is 230V +/-10% and 115V +/-10%.

So your 253V is just borderline, but anything higher is outside any specification.

Together with using 2A3's you may very well be exceeding component ratings etc. with this.

I hope the TRAM factory used the appropriate 240 volt thingies instead of Hong Kong thingies (110 volts???). Where to now??

The standard settings, unless ordered explicitly differently are according to current international standards, this means your voltages are not covered. Had you specified a normal mains voltage of > 250V AC diyhifisupply could have accommodated this, however non-standard mains voltages must be supplied.

Please take this up with Simon and point him to the post here, so you can arrange with him the way forward.

Ciao T

 

[bronal]

Hi Thorsten. Sorry if I sounded peeved in my last post. Anyway, yes the heater supply on the (right channel) 2A3 tube is out. Having taken my life in my hands I measured the voltage from the wall socket (with my little digitech multimeter). I kept the probes in for about 30 seconds. The voltage varied between 253 and 257. It's now 6.15pm on a Sunday evening so whether that has an effect I'm not sure. I hope the TRAM factory used the appropriate 240 volt thingies instead of Hong Kong thingies (110 volts???). Where to now??

Regards

Reggie

Hello Reggie: send your Tram to Decky and let him have a look at it. Voltage here in Canberra is about 245-250 most of the time, so our conditions are similar to yours. Decky can sort out the heater supplies plus do a few other mods as well. Cheaper than HK! Cheers Alan

 

[reggie]

Hello again Thorsten. Thank you for your response. It may surprise you to know that many people are not electronics savvy. We pay, plug and play and hope for the best. And that's why I purchased the TRAM assembled. I would not know a watt from an ampere and I certainly did not know, prior to receiving your email, that my power supply was anything other than 240 volts. So, thanks to you I now know how to take a voltage reading and that my power supply is (on average) 230 volts AC + 10% - 6%. at 50Hz Only it's not. My local electrician tells me that he is now reading more around the 250+ mark. I have also spoken to my local electricity retailer about my readings. They tell me that (a) they are bound to provide the 230v 10% - 6% (b) that there are several spikes during the day as they switch generators and (c) they agreed to provide a monitoring service to my house. However, despite the official line, I also note that in the territory where I live the Office of the Regulator General, in 2002, allowed a maximum impulse limit of 6kV and a maximum limit of 264 volts (low 216v). Anyway, I have arranged for my TRAM to be inspected and repaired locally. Several things come to mind. If my voltage exceeded the maximum 253 by point 016 volts then you must run some very close tolerances. Secondly, from reading this thread I understand I am not the first person to run foul of exceeding TRAM specifications so you must be aware of the situation. Thirdly, knowing that there is some question mark over the TRAM heater supply, I cannot understand why you say the onus should be on the purchaser (who may or may not be technically competent) and not the manufacturer to issue some form of warning regarding voltages and the use of the 2A3 tube or why you do not build in some additional leeway.
Regards

Reggie

Alan. I have arranged to send the TRAM to Decky. Thank you for the advice. I also looked at the SGR Audio outfit here in Melbourne that Decky represents in Canberra. Wow. The quality is amazing. They manufacture/machine most everything themselves. But $137,000 for their top of the line active speakers exceeds my reach.
Reggie

 

[ThorstenL]

Hi,

Hello again Thorsten. Thank you for your response. It may surprise you to know that many people are not electronics savvy. We pay, plug and play and hope for the best. And that's why I purchased the TRAM assembled.

I think this perhaps does not made clear. Even if assembled the Tram is a DIY Item. It means it makes some demands that commercial gear may not (or may) make.

However, the level of mains overvoltage is definitly an issue, not just for the Tram.

When I worked in London in Financial Computer systems we had similar levels of overvoltage. It kept killing the PC's (all from major corporate suppliers) we used, the servers where protected by UPS Systems but the batteries in these needed change at least every halve a year, or more frequent. The problem got so bad we eventually installed a massive dual conversion on-line UPS system for the whole building, one per floor at massive cost!

I also note that in the territory where I live the Office of the Regulator General, in 2002, allowed a maximum impulse limit of 6kV and a maximum limit of 264 volts (low 216v).

Diyhifisupply does rely on customers to inform them of the voltage needed, they cannot know every local voltage everywhere. I will ask for the web-pages to be updated to make this more clear.

Anyway, I have arranged for my TRAM to be inspected and repaired locally.

Please ask decky to get in touch with me regarding parts and settings etc.

Several things come to mind. If my voltage exceeded the maximum 253 by point 016 volts then you must run some very close tolerances.

0.16V are not an issue, but more than that, especially with 2A3 is.

The issue is you needed the Tram set for 250V, because your mains is in that ballpark, instead it was ordered and build for 230V. This means the Tram at your place runs very marginally to start with, being constantly run near the maximum limit. And then it gets extra voltage on top of that.

Secondly, from reading this thread I understand I am not the first person to run foul of exceeding TRAM specifications so you must be aware of the situation.

So far this has not a major issue in the US/EU bit it seems to affect Australia quite a lot. If Australia does apply very different limits (possibly by individual territory) than it means a special modified version is needed for Australia.

Thirdly, knowing that there is some question mark over the TRAM heater supply

There is NO questionmark. That was my point before as well.

It runs hot, but within specification and is reliable under normal circumstances including the use of 2A3 Tubes.

If you use tubes that have well above specification current draw and if you use the Tram II with voltages that significantly exceed design limits unreliability is a result.

Despite this I am sure you can come to a reasonable arrangement with Simon regarding repair, if you actually e-mail him, as I recommended. It seems you have not made any contact, normally Simon would have informed me.

Given the situation, namely that you did not know the level of mains voltage and that the website is not clear about the need to correctly specify the mains voltage, I would likely have recommended to try to help you as much as possible in getting things sorted.

I cannot understand why you say the onus should be on the purchaser (who may or may not be technically competent) and not the manufacturer to issue some form of warning regarding voltages and the use of the 2A3 tube or why you do not build in some additional leeway.

The Leeway build in suffices under normal circumstances. Without switched mode supplies it is not reasonable to try to cover such an extreme range of voltages in one design without modification..

If the circumstances are not normal, how is diyhifisupply to know, if not told? I fully understand your position of "but I did not know" as well. The normal way would be to discuss the issue with the supplier and find a way to resolve issues between you and supplier. This forum here is to discuss the products and provide technical support where needed/possible, but it is not the channel for resolving business related queries.

Kind regards T

 

[reggie]

Thank you Thorsten for your response. The major thing's I can take away from this are: the TRAM is fixable AND it is worth fixing AND DIYHiFi will modify their website to highlight the voltage/tube aspects to future purchasers.

Regards

Regie