jt1stcav Posted October 5, 2003 Share Posted October 5, 2003 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3051525041&category=39783&rd=1 Quote Link to comment Share on other sites More sharing options...
garymd Posted October 5, 2003 Share Posted October 5, 2003 Congrats Jim! Excellent buy, I think. I know absolutely nothing about this amp but it looks nice. I hope it gives you the sound you're looking for. What made you go for this particular amp? Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted October 5, 2003 Share Posted October 5, 2003 Ummmm....lordy. I remember when a member long ago talked of this option. Well, you did get yourself a tube amp finally. As for WHAT YOU DID GET, it's a tossup to be honest. I guess congratulations are in order. But somehow, I didnt exactly have this in mind for your first tube amp. Hope it works out for you. Compare it to your brother's 202a. kh Quote Link to comment Share on other sites More sharing options...
Deang Posted October 5, 2003 Share Posted October 5, 2003 AAHHRRRGGGGGGGGGG - I CAN'T SEE eBay. What the hell is it? Quote Link to comment Share on other sites More sharing options...
jt1stcav Posted October 5, 2003 Author Share Posted October 5, 2003 I was right in the middle of watching the DVD "K-19 The Widowmaker" with my youngest bro on his HT when my other brother Tom (who recently bought his JoLida JD 202a) paused the flick to tell me about a tube amp he just discovered on eBay. It was just posted a few hours ago with a BIN of $285. We read its description, then searched it on its "Ideal Innovations" website: http://www.idealinnovations.biz/ This Canadian PP tube amp is 20 watts per channel, which is a whole lot more than the lil' ZEN I was considering buying. After about 10 minutes of research, I decided..."What the hell!" I was immediately contacted by the owner in Ohio. I paid him through PayPal; he e-mailed me telling me he received his payment, and that he'll ship it FedEx Ground tomorrow. A little over an hour ago I was minding my own business watching a submarine flick, and now I'm a new owner of a PP vacuum tube stereo amplifier! Talk about impatient... Quote Link to comment Share on other sites More sharing options...
jt1stcav Posted October 5, 2003 Author Share Posted October 5, 2003 Dean, it's a 20 WPC PP amp from Ideal Innovations, the Traditional Model Stereo-40. Output tubes are four 6U5GT and two 12AX7 preamp tubes...I assume they're all NOS JAN military tubes from JJ Electronic(?). The website isn't very informative as far as I'm concerned, but I still haven't searched the entire site yet, so who knows what info I'll find. Don't know anything about 6U5GT output tubes...they're not 2A3s or EL34s, that's for sure. I don't know whether I would've chosen this amp on my own if it wasn't for the low BIN price and the immediate availability. Talk about spur-of-the-moment! Hope it wasn't a mistake. I guess I'll find out soon enough. It might be great little amp, and easy to modify. I'll probably do some tube rolling later on, but for now I'll just see how well it sounds as is. Quote Link to comment Share on other sites More sharing options...
jt1stcav Posted October 5, 2003 Author Share Posted October 5, 2003 The chassis is stamped steel with ventilation holes in back and on the bottom. 8 ohm taps are on the back, with the input RCA jacks up front between two gain controls (laid out similar to my Mac). I'll eventually upgrade the detachable power cord if I keep this amp. Don't know yet if the bias is adjustable, or is automatic. Quote Link to comment Share on other sites More sharing options...
Deang Posted October 5, 2003 Share Posted October 5, 2003 I've been all over the site, and there isn't anything there in there that goes into any detail regarding the type of push-pull circuit, or why they chose the output tubes they did. I did find the tube defined as a tetrode beam, which is the same as a KT-88 or 6550. However, the 6U5GT (or 6AV5GA), is an octal type, and only has a plate dissipation factor of 11 watts, as compared to the 35 watts of the 6550. It seems these amps are built around the idea of clean low power. http://www.r-type.org/static/cdrom.htm'> Quote Link to comment Share on other sites More sharing options...
jt1stcav Posted October 5, 2003 Author Share Posted October 5, 2003 Thanks for the explaination, Dean. But I'm wondering...not knowing diddly-squat about good output tubes like the 2A3 or 300B, is the 6U5GT of decent quality? You say it's equivilent to the KT88/6550...can the tetrode KT88 be substituted for the octal 6U5GT on this amplifier, or will the design of this amp prevent a tube exchange such as this, in your opinion? I know that you couldn't find any specs on the circuitry of this amp, neither could I. But even if I did, I wouldn't understand what I'm reading anyway. I wonder if the iron for this amp is of high quality, or will it be lacking? I hate not knowing this stuff! Like you and many others here, my dad grew up on vacuum tubes and understands them like the back of his hand. I'd e-mail him, but he's in Boston helping to reinstall the restored Aeolian-Skinner pipe organ back into the Boston Symphony Hall. Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted October 6, 2003 Share Posted October 6, 2003 That is one of the main questions I would have about this amplifier: OUTPUT IRON AND POWER TRANSFORMERS. It was one of the points I was trying to make regarding tube amps, SET amps in particular, but tube amps in general. Again, much of the quality of tube amps DOES come with the transformers with the OUTPUT TRANSFORMERS weighing in heavily. Many of the reasons why the vintage amps DO sound so good are the quality output iron used. Of course, the circuit and design is of great importance but it's still amazing how similar tube amps or today are to designs of yesterday. But when you have a stereo tube amplifier that comes in at below $300, than you know it's made to a price point. While many tube amps can be overachievers, certainly more so than solid state, there is a limit what you can expect. This looks to be a nice little amplifier for an amazing price. But you have to realize its limitations. Still, it is possible for a tube amplifier like this to really better the sound of most solid state amplifiers in the all important midrange. But with less quality solid state rectification circuit and average output iron, you might not get the same extension and definition that you desire. On the other hand, as I said above, most tube amplifiers are overachievers and even a modest tube amp can sound more realistic and natural than the McIntosh. One thing I WOULD do if I were you is find out WHICH MODEL THIS IS exactly. The 20w version of their amps actually uses the JAN 6AV5GA tube. I do believe the seller made two mistakes in his ad. I think you are actually getting the 10 watt version of the amplifier and not the 20w version. I actually believe the output tube in your model is the 6AU5GT which corresponds with their STEREO-20 amplifier (10w per channel). What is also unclear is exactly what the differences between the various traditional amp series besides the output tube. I personally think that an EICO HF-81/Scott 299/Fisher X101 would probably provide more refined sound than this amplifier but I do realize you wanted something right away. These vintage amplifiers ALL have very good output iron and when firing on all cylinders, really hold their own (my EICO HF-81 bettered the Jolida 302B with NOS by a pretty wide margin). I would call the company and find out about their Stereo-20 (this, after asking the seller what he believes the model to be - I think the 20 corresponded to the model, not the watts). At the least, you will be able to sell this amp without much of a loss and it will provide some good experience. Who knows, it might turn out to be a little low cost gem (relatively speaking). You sure dont have much invested. I hope it works out for you one way or another. kh ps- On tube experience, you shouldnt feel outside the loop. READ the archives here and do research via GOOGLE online (there are many beginner tube sites with the basics). Search the Audio Asylum tube forums. Peruse the Newsgroups. GET A TUBE AMP AND TRY IT OUT. Remember, 95% of the people here are brand new to tubes, relatively speaking. Even many of the posters people assume have been messing with tube amps for many years only have less than 20 or so months experience with tube audio. Look to this to show you what you can learn in a short time with experience and some research. The INTERNET is a godsend for this type of thing. OF course, you have to weed through the gibberish, but there is MUCH info, and GOOD info at that. Quote Link to comment Share on other sites More sharing options...
bkrop Posted October 6, 2003 Share Posted October 6, 2003 Holy impetuousness Batman! Quote Link to comment Share on other sites More sharing options...
Randy Bey Posted October 6, 2003 Share Posted October 6, 2003 Jim, IMHO, a better choice than a Zen. MH is right especially regarding transformers; a rule of thumb should be that the amp is freekin' heavy. Pounds per watt should be around 8-10. I spedred their web site and they seem to say the right things. Good transformers cost as much as they sell the entire amp for, to dangle a participle. The paucity of tubes is a puzzler. Must have SS power regulation, I suppose. But the proof is in the puddin, and listening tests are the only valid indicator of success. Do let us know how it turns out. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted October 6, 2003 Share Posted October 6, 2003 I'm beginning to wonder about the importance of "Quality Output Iron" on Push Pull amplifiers (this will be another reversal in thought for me). My latest project as you know Kelly is a New set of custom mono blocks using Mark III reproduction transformers. I now have one of these amps built up and working fine (after some real stupid wiring errors that almost drove me nuts, teaches me to work on this stuff into the wee hours). I have my new amp with new Iron playing the right channel and my Original and similarly redesigned Mark III on the Left channel. This is not a very Scientific test but I can not hear any discrepancy channel to channel the 2 amps mate perfectly together. I will be putting these thru a barrage of tests on the scope some time this week with Mark Deneen coaching me thru the finer testing points on both amps. I'm going to be real surprised if any large difference is found. Now with SET this maybe a different story all together from everything I have read about these SET amps they are very touchy about the circuit and components front to back. More to come on this later ! Craig Quote Link to comment Share on other sites More sharing options...
Painful Reality Posted October 6, 2003 Share Posted October 6, 2003 ---------------- On 10/6/2003 7:23:15 AM NOSValves wrote: I'm beginning to wonder about the importance of "Quality Output Iron" on Push Pull amplifiers (this will be another reversal in thought for me). My latest project as you know Kelly is a New set of custom mono blocks using Mark III reproduction transformers. I now have one of these amps built up and working fine (after some real stupid wiring errors that almost drove me nuts, teaches me to work on this stuff into the wee hours). I have my new amp with new Iron playing the right channel and my Original and similarly redesigned Mark III on the Left channel. This is not a very Scientific test but I can not hear any discrepancy channel to channel the 2 amps mate perfectly together. I will be putting these thru a barrage of tests on the scope some time this week with Mark Deneen coaching me thru the finer testing points on both amps. I'm going to be real surprised if any large difference is found. Now with SET this maybe a different story all together from everything I have read about these SET amps they are very touchy about the circuit and components front to back. More to come on this later ! Craig ---------------- Craig, irons do matter even in push-pull. You are right in saying irons matter more in SET due to the huge level of standing current in it. It's "trickier" to design a good SET OPT to avoid core saturation. And, contrary to a PP, a poor OPT will ruin the SET potential to great sound. A pedestrian OPT in a PP amp won't make a good circuit sounds bad. It won't just sound as good as if it would have an excellent OPT. The question is, as always,: am I ready to spend more to see sonic differences that are rarely in proportion with the increase in cost. Some will, some won't. Quote Link to comment Share on other sites More sharing options...
leok Posted October 6, 2003 Share Posted October 6, 2003 Those 6U5GT may be closer to the KT66 than the KT88. I don't know the biasing or pinout. I did place the spec sheet for the KT66 on another thread here. I'll see if I can do some comparison. leok Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted October 6, 2003 Share Posted October 6, 2003 Leo, I still dont see much of anything on the 6U5 while I DO FIND info via data and my tube tester on 6AU5. I think this might have been a typo by the seller as I said above. IF anyone DOES have info on the 6U5, I would be interested to see it. I think this amp was misrepresented in the ad, possibly by accident. It appears to be the 10w model and not the 20w. Craig, as for output iron, I do think there is a difference but agree with Jeff's assessment. What was the music you were comparing the two channels with? Also, I would hold out till you get the other channel completed and listen as a stereo pair. Will be interesting to see the measurements but I still think our testing is behind on relating to what the gear sounds like and how it will perform. I think if you listened to a pair with MQ iron against the HandWound iron, you would tell a difference given the proper testing, conditions, and variety of music to bring out diff aspects of playback. Then again, it may be showing that the HandWound iron is a good deal! kh Quote Link to comment Share on other sites More sharing options...
leok Posted October 6, 2003 Share Posted October 6, 2003 So far I've found that the 6U5 it is a flourescent display device. I wouldn't think that the GT suffix would turn it into an output tube. Dean seems to have a better fix on whatever it is. leok Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted October 6, 2003 Share Posted October 6, 2003 I think Dean just looked up the 6AV5GA when he saw Jim was referring to the Stereo-40 amp. I have barely found a smidgeon on the 6U5. Look up the 6AU5 and you get a variety of info (it's ALSO the tube the company LISTS as going into their STEREO 20 amp). kh Quote Link to comment Share on other sites More sharing options...
Deang Posted October 6, 2003 Share Posted October 6, 2003 Yep, that's exactly what I did: The "Traditional Stereo-20" is 10 wpc, and actually uses the 6AU5GT. http://hereford.ampr.org/cgi-bin/tube?tube=6AU5GT The "Stereo-40" is the 20 wpc model and uses the 6AV5GTA http://hereford.ampr.org/cgi-bin/tube?tube=6AV5GA The ad may not be "wrong", since these tubes appear to be substitutes for one another. However, it is likely that Kelly is right, and that it is indeed the Stereo-20 (10 wpc). These tubes are listed as "Horizontal Beam Tubes", and were used as deflectors in televisions (TV Horizontal Deflection). Actually Kelly, this thing is probably right up your alley. A simple push-pull which I think might be perfect in giving Jim a great taste of what tubes can do! BTW, I think Jeff and Craig should both check out the chassis' they sell. Not bad, not bad at all. Quote Link to comment Share on other sites More sharing options...
Deang Posted October 6, 2003 Share Posted October 6, 2003 Jim, no -- you cannot substitute KT-88's or 6550's for what is in this amp. The tubes are really totally different animals electrically speaking. Quote Link to comment Share on other sites More sharing options...
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